2016 Vol. 33, No. 11
2016, 33(11): 2405-2411.
doi: 10.13801/j.cnki.fhclxb.20151209.003
Abstract:
Nano-TiO2/polycarbonate-polypropylene (TiO2/PC-PP) light diffusion composites were prepared by melt mixing method. The microscopic structure and isothermal crystallization behaviors of nano-TiO2/PC-PP light diffusion composites were investigated by SEM and DSC, respectively, and the thermal stability and optical property of the composites were investigated. The results show that the average size of the dispersed phase in the optical diffusion system becomes smaller with the addition of nano-TiO2 and the morphology is more uniform. The half crystallization time of the composites is prolonged, and the overall crystallization rate becomes slower with the increase of mass fraction for nano-TiO2 in the composites. The addition of nano-TiO2 makes the initial thermal degradation temperatures and the final residual weights of the composites increase. When the mass fraction of nano-TiO2 in PP is 5%, the transmittance of the composites is 80% and the haze is 88%, which is the preferably light diffusion performance of the nano-TiO2/PC-PP light diffusion composites.
Nano-TiO2/polycarbonate-polypropylene (TiO2/PC-PP) light diffusion composites were prepared by melt mixing method. The microscopic structure and isothermal crystallization behaviors of nano-TiO2/PC-PP light diffusion composites were investigated by SEM and DSC, respectively, and the thermal stability and optical property of the composites were investigated. The results show that the average size of the dispersed phase in the optical diffusion system becomes smaller with the addition of nano-TiO2 and the morphology is more uniform. The half crystallization time of the composites is prolonged, and the overall crystallization rate becomes slower with the increase of mass fraction for nano-TiO2 in the composites. The addition of nano-TiO2 makes the initial thermal degradation temperatures and the final residual weights of the composites increase. When the mass fraction of nano-TiO2 in PP is 5%, the transmittance of the composites is 80% and the haze is 88%, which is the preferably light diffusion performance of the nano-TiO2/PC-PP light diffusion composites.
2016, 33(11): 2412-2418.
doi: 10.13801/j.cnki.fhclxb.20160126.002
Abstract:
SiO2/polyvinyl alcohol (PVA) hydrogel scaffold with different porosities was prepared by two-step method of pre forming and post freezing cross-linking using 3D printing technology. The reproducible friction behaviors of SiO2/PVA hydrogel scaffold was researched and the friction principle of SiO2/PVA hydrogel scaffold was analyzed. The results show that SiO2/PVA hydrogel scaffold can keep a three dimensional through structure with maximum porosity of 42.3%. At low friction velocity(10-6-10-3 m/s), the frictional force of SiO2/PVA hydrogel scaffold is slightly higher than that of bulk SiO2/PVA hydrogel and decreases slightly with the increase of porosity. At high friction velocity(10-2-1 m/s), the frictional force of SiO2/PVA hydrogel scaffold is equal to that of bulk SiO2/PVA hydrogel and the effect of porosity on the frictional force for scaffold is not obvious. At small normal pressure load(0.3 kPa), SiO2/PVA hydrogel scaffold shows better reproducible friction property than bulk SiO2/PVA hydrogel. It is related to the structure of the scaffold which can keep a stable hydrated lubrication layer.
SiO2/polyvinyl alcohol (PVA) hydrogel scaffold with different porosities was prepared by two-step method of pre forming and post freezing cross-linking using 3D printing technology. The reproducible friction behaviors of SiO2/PVA hydrogel scaffold was researched and the friction principle of SiO2/PVA hydrogel scaffold was analyzed. The results show that SiO2/PVA hydrogel scaffold can keep a three dimensional through structure with maximum porosity of 42.3%. At low friction velocity(10-6-10-3 m/s), the frictional force of SiO2/PVA hydrogel scaffold is slightly higher than that of bulk SiO2/PVA hydrogel and decreases slightly with the increase of porosity. At high friction velocity(10-2-1 m/s), the frictional force of SiO2/PVA hydrogel scaffold is equal to that of bulk SiO2/PVA hydrogel and the effect of porosity on the frictional force for scaffold is not obvious. At small normal pressure load(0.3 kPa), SiO2/PVA hydrogel scaffold shows better reproducible friction property than bulk SiO2/PVA hydrogel. It is related to the structure of the scaffold which can keep a stable hydrated lubrication layer.
2016, 33(11): 2419-2425.
doi: 10.13801/j.cnki.fhclxb.20160108.002
Abstract:
A series of nano Al2O3/polyimide (Al2O3/PI) composite films with different mass fraction of nano Al2O3 particles were successfully prepared via in situ polymerisation and thermal imidization method. The microstructure, dielectric property and mechanical property of nano Al2O3/PI composite films were characterized and measured by SEM, TEM, XRD, FTIR, LCR meter, high voltage power and the electronic universal material testing machine. The results show that nano Al2O3 particles disperse evenly in the PI matrix. The breakdown strength and tensile strength of nano Al2O3/PI composite films both reach a maximum value with nano Al2O3 particles mass fraction of 8%. The dielectric constants of nano Al2O3/PI composite films increase with the increasing of mass fraction for nano Al2O3.
A series of nano Al2O3/polyimide (Al2O3/PI) composite films with different mass fraction of nano Al2O3 particles were successfully prepared via in situ polymerisation and thermal imidization method. The microstructure, dielectric property and mechanical property of nano Al2O3/PI composite films were characterized and measured by SEM, TEM, XRD, FTIR, LCR meter, high voltage power and the electronic universal material testing machine. The results show that nano Al2O3 particles disperse evenly in the PI matrix. The breakdown strength and tensile strength of nano Al2O3/PI composite films both reach a maximum value with nano Al2O3 particles mass fraction of 8%. The dielectric constants of nano Al2O3/PI composite films increase with the increasing of mass fraction for nano Al2O3.
2016, 33(11): 2426-2435.
doi: 10.13801/j.cnki.fhclxb.20160229.003
Abstract:
Expanded vermiculite/phenolic flame retardant and insulation composites were prepared by compounding expanded vermiculite as a flame retardant and phenolic resin via a medium temperature foaming method. The effects of foaming temperature, content of curing agent, content of foaming agent, content of surfactant, curing time and content of expanded vermiculite on flame retardant and thermal insulation performances of expanded vermiculite/phenolic flame retardant and insulation composites were analyzed by limit oxygen index, cone calorimetry, thermal conductivity and apparent density. The results show that expanded vermiculite/phenolic flame retardant and insulation composites prepared by expanded vermiculite as a flame retardant show good flame resistance, good insulation and low apparent density. The results of single factor experiment show that the optimized conditions of expanded vermiculite/phenolic flame retardant and insulation composites are that the foaming temperature is 80℃, content of curing agent is 10wt%, content of foaming agent is 10wt%, content of surfactant is 5wt%, curing time is 2 h and content of expanded vermiculite is 60wt%, under which, the apparent density of expanded vermiculite/phenolic flame retardant and insulation composites is 190.08 kg/m3, the compressive strength is 0.32 MPa, the thermal conductivity is 0.054 9 W/(m·K), the limit oxygen index is 71.1%, the average heat release rate is 15 kW/m2.
Expanded vermiculite/phenolic flame retardant and insulation composites were prepared by compounding expanded vermiculite as a flame retardant and phenolic resin via a medium temperature foaming method. The effects of foaming temperature, content of curing agent, content of foaming agent, content of surfactant, curing time and content of expanded vermiculite on flame retardant and thermal insulation performances of expanded vermiculite/phenolic flame retardant and insulation composites were analyzed by limit oxygen index, cone calorimetry, thermal conductivity and apparent density. The results show that expanded vermiculite/phenolic flame retardant and insulation composites prepared by expanded vermiculite as a flame retardant show good flame resistance, good insulation and low apparent density. The results of single factor experiment show that the optimized conditions of expanded vermiculite/phenolic flame retardant and insulation composites are that the foaming temperature is 80℃, content of curing agent is 10wt%, content of foaming agent is 10wt%, content of surfactant is 5wt%, curing time is 2 h and content of expanded vermiculite is 60wt%, under which, the apparent density of expanded vermiculite/phenolic flame retardant and insulation composites is 190.08 kg/m3, the compressive strength is 0.32 MPa, the thermal conductivity is 0.054 9 W/(m·K), the limit oxygen index is 71.1%, the average heat release rate is 15 kW/m2.
Friction and wear properties of potassium titanate whisker-glass fiber/benzoxazine hybrid composites
2016, 33(11): 2436-2443.
doi: 10.13801/j.cnki.fhclxb.20160114.003
Abstract:
Potassium titanate whisker (K2O·6TiO2) was utilized to modifiy the friction and wear properties of benzoxazine (BOZ) resin and glass fiber/benzoxzine (GF/BOZ)composites. Friction and wear properties and modification mechanism of K2O·6TiO2/BOZ composites and K2O·6TiO2-GF/BOZ hybrid composites were analyzed. The results show that the friction coefficients and specific wear rates of K2O·6TiO2/BOZ composites and K2O·6TiO2-GF/BOZ hybrid composites decrease significantly compared with BOZ resin and GF/BOZ composites due to the addition of K2O·6TiO2. K2O·6TiO2 significantly alleviate the friction adhesion of BOZ resin and GF/BOZ composites and reduce the friction coefficients. Meanwhile the abrasive wear are also alleviated. During the friction process of the GF/BOZ composites, friction stress firstly break the interface between GF and BOZ resin, and then induce the destruction of BOZ resins in and between the GF bundles and GF interlaminations, making the friction coefficient of GF/BOZ composites lower than that of BOZ resin but the specific wear rates higher than that of BOZ resin. With the incorporation of K2O·6TiO2, the specific wear rate of K2O·6TiO2-GF/BOZ hybrid composites effectively reduces. The friction coefficients and specific wear rates of BOZ resin, GF/BOZ composites and K2O·6TiO2-GF/BOZ hybrid composites are 0.34 and 0.66×10-6 mm3·(N·m)-1, 0.19 and 1.2×10-6 mm3·(N·m)-1, 0.09 and 0.69×10-6 mm3·(N·m)-1, respectively.
Potassium titanate whisker (K2O·6TiO2) was utilized to modifiy the friction and wear properties of benzoxazine (BOZ) resin and glass fiber/benzoxzine (GF/BOZ)composites. Friction and wear properties and modification mechanism of K2O·6TiO2/BOZ composites and K2O·6TiO2-GF/BOZ hybrid composites were analyzed. The results show that the friction coefficients and specific wear rates of K2O·6TiO2/BOZ composites and K2O·6TiO2-GF/BOZ hybrid composites decrease significantly compared with BOZ resin and GF/BOZ composites due to the addition of K2O·6TiO2. K2O·6TiO2 significantly alleviate the friction adhesion of BOZ resin and GF/BOZ composites and reduce the friction coefficients. Meanwhile the abrasive wear are also alleviated. During the friction process of the GF/BOZ composites, friction stress firstly break the interface between GF and BOZ resin, and then induce the destruction of BOZ resins in and between the GF bundles and GF interlaminations, making the friction coefficient of GF/BOZ composites lower than that of BOZ resin but the specific wear rates higher than that of BOZ resin. With the incorporation of K2O·6TiO2, the specific wear rate of K2O·6TiO2-GF/BOZ hybrid composites effectively reduces. The friction coefficients and specific wear rates of BOZ resin, GF/BOZ composites and K2O·6TiO2-GF/BOZ hybrid composites are 0.34 and 0.66×10-6 mm3·(N·m)-1, 0.19 and 1.2×10-6 mm3·(N·m)-1, 0.09 and 0.69×10-6 mm3·(N·m)-1, respectively.
2016, 33(11): 2444-2453.
doi: 10.13801/j.cnki.fhclxb.20160114.002
Abstract:
The solid phase grafting product methyl methacrylate grafting sugarcane bagasse (SCB-g-MMA) was prepared by the methyl methacrylate (MMA) grafted sugarcane bagasse (SCB) surface after alkali treatment through solid phase grafting method. And its structure was characterized and analyzed by XRD, FTIR, 13C NMR, SEM and Brunauer-Emmett-Teller (BET) methods etc. Then the SCB-g-MMA was applied to adsorb methylene blue (MB) and adsorption property investigation was carried out. The results show that when the initial concentration of MB is 50-400 mg/L, pH value of aqueous solution is 6-12, dosage of adsorbent is more than 10 g/L and adsorption time is more than 40 min, the removal efficiency of MB by SCB-g-MMA is 99% at room temperature. And when the dosage of adsorbent is 2.5 g/L, the adsorption capacity of MB is 97.3 mg/g. In addition, the adsorption kinetics and the adsorption isotherm of SCB-g-MMA for MB are more fitted to the pseudo-second-order kinetic equation and Freundlich isotherm adsorption model, respectively.
The solid phase grafting product methyl methacrylate grafting sugarcane bagasse (SCB-g-MMA) was prepared by the methyl methacrylate (MMA) grafted sugarcane bagasse (SCB) surface after alkali treatment through solid phase grafting method. And its structure was characterized and analyzed by XRD, FTIR, 13C NMR, SEM and Brunauer-Emmett-Teller (BET) methods etc. Then the SCB-g-MMA was applied to adsorb methylene blue (MB) and adsorption property investigation was carried out. The results show that when the initial concentration of MB is 50-400 mg/L, pH value of aqueous solution is 6-12, dosage of adsorbent is more than 10 g/L and adsorption time is more than 40 min, the removal efficiency of MB by SCB-g-MMA is 99% at room temperature. And when the dosage of adsorbent is 2.5 g/L, the adsorption capacity of MB is 97.3 mg/g. In addition, the adsorption kinetics and the adsorption isotherm of SCB-g-MMA for MB are more fitted to the pseudo-second-order kinetic equation and Freundlich isotherm adsorption model, respectively.
2016, 33(11): 2454-2460.
doi: 10.13801/j.cnki.fhclxb.20160114.001
Abstract:
By surface covering modification technology, nano CeO2 was modified by stearic acid, the modified nano m-CeO2 and phenyl hydrogen containing silicone resin (PH) were chemically graftinged to prepare m-CeO2-PH grafting. Atransparent m-CeO2/phenyl-silicone rubber materials used for light-emitting diode (LED) packaging materials were prepared by the method of hydrogenation with grafting as cross-linking agent under the platinum catalyst.The results show that stearic acid salt produces on surface of m-CeO2 after modified by stearic acid, which increases the compatibility of the interface and improves the dispersion of nano CeO2 in polymer. m-CeO2 was grafted in PH system by chemical method, then reacted with phenyl vinyl silicone resin (PV) with stoichiometric ratio under catalyst, and functional m-CeO2/phenyl-silicone rubber materials were prepared through high temperature curing. Research shows that the light transmission rate of m-CeO2/phenyl-silicone rubber materials reaches above 85% with 0.02% mass fraction of m-CeO2, and ultraviolet aging properties and mechanical properties increase obviously. In addition when 0.02% mass fraction m-CeO2 was introduced in phenyl-silicone rubber materials and decomposition temperature of CeO2/silicone rubber composites is 600℃, the thermel gravimetric loss rate of m-CeO2/phenyl-silicone rubber materials will cut down 8% than pure phenyl-silicone rubber, heat release of m-CeO2/phenyl-silicone rubber materials is obviously lower than that of pure phenyl-silicone rubber which has superiority for LED packaging materials.
By surface covering modification technology, nano CeO2 was modified by stearic acid, the modified nano m-CeO2 and phenyl hydrogen containing silicone resin (PH) were chemically graftinged to prepare m-CeO2-PH grafting. Atransparent m-CeO2/phenyl-silicone rubber materials used for light-emitting diode (LED) packaging materials were prepared by the method of hydrogenation with grafting as cross-linking agent under the platinum catalyst.The results show that stearic acid salt produces on surface of m-CeO2 after modified by stearic acid, which increases the compatibility of the interface and improves the dispersion of nano CeO2 in polymer. m-CeO2 was grafted in PH system by chemical method, then reacted with phenyl vinyl silicone resin (PV) with stoichiometric ratio under catalyst, and functional m-CeO2/phenyl-silicone rubber materials were prepared through high temperature curing. Research shows that the light transmission rate of m-CeO2/phenyl-silicone rubber materials reaches above 85% with 0.02% mass fraction of m-CeO2, and ultraviolet aging properties and mechanical properties increase obviously. In addition when 0.02% mass fraction m-CeO2 was introduced in phenyl-silicone rubber materials and decomposition temperature of CeO2/silicone rubber composites is 600℃, the thermel gravimetric loss rate of m-CeO2/phenyl-silicone rubber materials will cut down 8% than pure phenyl-silicone rubber, heat release of m-CeO2/phenyl-silicone rubber materials is obviously lower than that of pure phenyl-silicone rubber which has superiority for LED packaging materials.
2016, 33(11): 2461-2467.
doi: 10.13801/j.cnki.fhclxb.20160315.016
Abstract:
A novel flame retardant containing phosphorus and nitrogen (PNFR) was synthesized by the reaction between 1, 3, 5-tris(2-hydroxyethyl)isocyanurate(THEIC) and phenyl dichlorophosphate(PDCP), and its structure and composition were characterized by FTIR, nuclear magnetic resonance spectroscopy (1H-NMR and 31P-NMR), respectively. PNFR was compounded with ammonium polyphosphate(APP) applied to prepare ammonium polyphosphate-novel flame retardant and polyurethane foam (APP-PNFR/PUF) composites, and the flame retardancy and thermal property of APP-PNFR/PUF composites were respectively investigated by limiting oxygen index (LOI), vertical burning testing, cone calorimeter testing and thermogravimetric analysis. The results show that the PNFR is successfully prepared. TGA of PNFR suggests that it has good thermal stability with initial degradation temperature 249℃, and the residue of PNFR is 33.7% at 800℃ under nitrogen atmosphere. The addition of APP-PNFR effectively enhances the flame retardany of polyurethane foam(PUF), and especially when the loading amount of PNFR is 7.5% based on the premixed polyether polyols' weight, the APP-PNFR/PUF has optimum comprehensive properties with LOI increasing from 19% to 24%, and UL-94 vertical burning grade reaching V-0 level. Meanwhile, the peak heat release rate of APP-PNFR/PUF3 decreases from 110.6 kW/m2 to 94.5 kW/m2. Additionally, the initial degradation temperature of APP-PNFR/PUF3 increases by 6℃, maximum decomposition rate decreases by 16.3%, and the residue is 33.5% at 800℃ under nitrogen atmosphere. The incorporation of PNFR does not impair the physical mechanical property of PUF.
A novel flame retardant containing phosphorus and nitrogen (PNFR) was synthesized by the reaction between 1, 3, 5-tris(2-hydroxyethyl)isocyanurate(THEIC) and phenyl dichlorophosphate(PDCP), and its structure and composition were characterized by FTIR, nuclear magnetic resonance spectroscopy (1H-NMR and 31P-NMR), respectively. PNFR was compounded with ammonium polyphosphate(APP) applied to prepare ammonium polyphosphate-novel flame retardant and polyurethane foam (APP-PNFR/PUF) composites, and the flame retardancy and thermal property of APP-PNFR/PUF composites were respectively investigated by limiting oxygen index (LOI), vertical burning testing, cone calorimeter testing and thermogravimetric analysis. The results show that the PNFR is successfully prepared. TGA of PNFR suggests that it has good thermal stability with initial degradation temperature 249℃, and the residue of PNFR is 33.7% at 800℃ under nitrogen atmosphere. The addition of APP-PNFR effectively enhances the flame retardany of polyurethane foam(PUF), and especially when the loading amount of PNFR is 7.5% based on the premixed polyether polyols' weight, the APP-PNFR/PUF has optimum comprehensive properties with LOI increasing from 19% to 24%, and UL-94 vertical burning grade reaching V-0 level. Meanwhile, the peak heat release rate of APP-PNFR/PUF3 decreases from 110.6 kW/m2 to 94.5 kW/m2. Additionally, the initial degradation temperature of APP-PNFR/PUF3 increases by 6℃, maximum decomposition rate decreases by 16.3%, and the residue is 33.5% at 800℃ under nitrogen atmosphere. The incorporation of PNFR does not impair the physical mechanical property of PUF.
2016, 33(11): 2468-2476.
doi: 10.13801/j.cnki.fhclxb.20160307.003
Abstract:
Poly(phenylene sulfide) (PPS) is an insulating and hydrophobic material, which somewhat limits its certain applications in some specific fields. The amino-group modified PPS (NPPS) was prepared, and NPPS was further modified with epoxy-functionalized muti-walled carbon nanotubes (EFMWCNTs) by solution blending method via covalent interaction, and EFMWCNTs/NPPS conductive composites were prepared. The structure and properties of composites were characterized by various techniques including FTIR, XPS, XRD, FESEM, TEM, DSC, TGA and semiconductor powder resistivity tester. Characterization results show that when amino-group was introduced into the chain segment of PPS, the melting peak and crystalline peak of PPS disappear. After NPPS is further modified with EFMWCNTs, compared with NPPS, the thermal stability of EFMWCNTs/NPPS conductive composites increases because EFMWCNTs were attached onto NPPS by covalent bond which is effective to disperse EFMWCNTs into NPPS matrix. Electrical conductivity of EFMWCNTs/NPPS composites increases with the increase of EFMWCNTs content. The electrical conductivity of composite is 6.1×10-2 S/cm with loading 10wt% EFMWCNTs.
Poly(phenylene sulfide) (PPS) is an insulating and hydrophobic material, which somewhat limits its certain applications in some specific fields. The amino-group modified PPS (NPPS) was prepared, and NPPS was further modified with epoxy-functionalized muti-walled carbon nanotubes (EFMWCNTs) by solution blending method via covalent interaction, and EFMWCNTs/NPPS conductive composites were prepared. The structure and properties of composites were characterized by various techniques including FTIR, XPS, XRD, FESEM, TEM, DSC, TGA and semiconductor powder resistivity tester. Characterization results show that when amino-group was introduced into the chain segment of PPS, the melting peak and crystalline peak of PPS disappear. After NPPS is further modified with EFMWCNTs, compared with NPPS, the thermal stability of EFMWCNTs/NPPS conductive composites increases because EFMWCNTs were attached onto NPPS by covalent bond which is effective to disperse EFMWCNTs into NPPS matrix. Electrical conductivity of EFMWCNTs/NPPS composites increases with the increase of EFMWCNTs content. The electrical conductivity of composite is 6.1×10-2 S/cm with loading 10wt% EFMWCNTs.
2016, 33(11): 2477-2484.
doi: 10.13801/j.cnki.fhclxb.20160315.004
Abstract:
The electrical properties and rheology for polymer based conductive composites were investigated, in which acrylonitrile-butadiene-styrene copolymer (ABS) and polyvinylidene fluoride (PVDF) were used as the matrix and stainless steel fibers (SSF) and graphite were used as conductive fillers, and the SSF-graphite/ABS-PVDF conductive composites were prepared by melt-blending method. The distribution of conductive filler, the conductive property and phase transition behavior of SSF/ABS-PVDF composite system were studied. The results show that SSF tends to locate in the PVDF phase, and when the SSF content is 20wt%, the electrical resistivity of SSF/ABS-PVDF composites decreases firstly, and after then reaches a platform region, finally decreases again with the increase of PVDF ratio. Phase transition behavior occurs when content of PVDF is 30wt%-40wt% and 70wt%-80wt% in ABS-PVDF composite matrix. A double percolation phenomenon appeares in the SSF-graphite/ABS-PVDF composites when content of SSF is 16.84wt% and 25wt%-30wt% which is consistent with the tendency of dynamic modulus and complex viscosity.
The electrical properties and rheology for polymer based conductive composites were investigated, in which acrylonitrile-butadiene-styrene copolymer (ABS) and polyvinylidene fluoride (PVDF) were used as the matrix and stainless steel fibers (SSF) and graphite were used as conductive fillers, and the SSF-graphite/ABS-PVDF conductive composites were prepared by melt-blending method. The distribution of conductive filler, the conductive property and phase transition behavior of SSF/ABS-PVDF composite system were studied. The results show that SSF tends to locate in the PVDF phase, and when the SSF content is 20wt%, the electrical resistivity of SSF/ABS-PVDF composites decreases firstly, and after then reaches a platform region, finally decreases again with the increase of PVDF ratio. Phase transition behavior occurs when content of PVDF is 30wt%-40wt% and 70wt%-80wt% in ABS-PVDF composite matrix. A double percolation phenomenon appeares in the SSF-graphite/ABS-PVDF composites when content of SSF is 16.84wt% and 25wt%-30wt% which is consistent with the tendency of dynamic modulus and complex viscosity.
2016, 33(11): 2485-2491.
doi: 10.13801/j.cnki.fhclxb.20160321.001
Abstract:
The survival rate and testing accuracy of embedded fiber Bragg grating (FBG) sensors are the precondition to on-line monitor the manufacturing and working status of fiber reinforced resin matrix composites. The stacking sequence of carbon fiber prepregs is[9011/011]. The FBG temperature and strain sensors were embedded into the typical positions of the laminates along 0° and 45° directions, and then the composite laminates were manufactured by compression molding method. Four kinds of methods were used to protect fiber grating sensors when they were embedded into the laminates in direction of 45° where the fiber grating direction is not parallel to the carbon fiber direction. By the comparison of the experimental results, it can be concluded that the embedded FBG sensors which were not parallel to the carbon fiber direction were easily inactivated in the hot compression molding process without any additional protection; the method of laying several whole layers of synclastic prepregs to protect the FBG sensors which were not parallel to the carbon fiber direction has changed the mechanical performance of composites with specific layer parameters; the measurement error of the strain sensors would be enlarged if two narrow prepreg strips on both sides of the sensors were introduced to protect the sensors; the survival rate and testing accuracy of the fiber Bragg gratings would be significantly improved through the method in which two narrow prepreg strips on both sides of the sensors and opening grooves on the neighboring layers were used to protect the sensors.
The survival rate and testing accuracy of embedded fiber Bragg grating (FBG) sensors are the precondition to on-line monitor the manufacturing and working status of fiber reinforced resin matrix composites. The stacking sequence of carbon fiber prepregs is[9011/011]. The FBG temperature and strain sensors were embedded into the typical positions of the laminates along 0° and 45° directions, and then the composite laminates were manufactured by compression molding method. Four kinds of methods were used to protect fiber grating sensors when they were embedded into the laminates in direction of 45° where the fiber grating direction is not parallel to the carbon fiber direction. By the comparison of the experimental results, it can be concluded that the embedded FBG sensors which were not parallel to the carbon fiber direction were easily inactivated in the hot compression molding process without any additional protection; the method of laying several whole layers of synclastic prepregs to protect the FBG sensors which were not parallel to the carbon fiber direction has changed the mechanical performance of composites with specific layer parameters; the measurement error of the strain sensors would be enlarged if two narrow prepreg strips on both sides of the sensors were introduced to protect the sensors; the survival rate and testing accuracy of the fiber Bragg gratings would be significantly improved through the method in which two narrow prepreg strips on both sides of the sensors and opening grooves on the neighboring layers were used to protect the sensors.
2016, 33(11): 2492-2499.
doi: 10.13801/j.cnki.fhclxb.20160401.001
Abstract:
In order to establish the theoretical model for long-term stiffness of fiber reinforced plastic pipes, and predict the long-term stiffness of them, using the autonomous designed constant displacement loading test apparatus, the testing investigations for long-term stiffness of glass fiber reinforced plastic pipes with of pure hoop winding and pure cross winding plies were performed under constant displacement conditions of different initial deflections firstly. Then, stiffness vs time broken line log-log regression model of glass fiber reinforced plastic pipes under different initial deflections, linear regression model of stiffness degradation rate after 50 years vs initial deflection were established based on the test, thus quadratic surfaces prediction model of glass fiber reinforced plastic pipes stiffness degradation rate vs time and initial deflection was proposed. Finally, the residual stiffness of glass fiber reinforced plastic pipes after 50 years was predicted, and the effects of time and initial deflection on stiffness of glass fiber reinforced plastic pipes were investigated. The results show that the ability to resist stiffness degradation of glass fiber reinforced plastic pipes with pure hoop winding ply are much more superior to that of glass fiber reinforced plastic pipes with pure cross winding ply, pure hoop winding ply can improve the stiffness of glass fiber reinforced plastic pipes and the ability to resist radial deformation of them effectively, glass fiber reinforced plastic pipes with pure hoop winding ply have better long-term mechanical performances. The test data when the time is 8 313.2 h indicates that the proposed prediction model for stiffness degradation rate of glass fiber reinforced plastic pipes has relatively high precision and relatively great applicability.
In order to establish the theoretical model for long-term stiffness of fiber reinforced plastic pipes, and predict the long-term stiffness of them, using the autonomous designed constant displacement loading test apparatus, the testing investigations for long-term stiffness of glass fiber reinforced plastic pipes with of pure hoop winding and pure cross winding plies were performed under constant displacement conditions of different initial deflections firstly. Then, stiffness vs time broken line log-log regression model of glass fiber reinforced plastic pipes under different initial deflections, linear regression model of stiffness degradation rate after 50 years vs initial deflection were established based on the test, thus quadratic surfaces prediction model of glass fiber reinforced plastic pipes stiffness degradation rate vs time and initial deflection was proposed. Finally, the residual stiffness of glass fiber reinforced plastic pipes after 50 years was predicted, and the effects of time and initial deflection on stiffness of glass fiber reinforced plastic pipes were investigated. The results show that the ability to resist stiffness degradation of glass fiber reinforced plastic pipes with pure hoop winding ply are much more superior to that of glass fiber reinforced plastic pipes with pure cross winding ply, pure hoop winding ply can improve the stiffness of glass fiber reinforced plastic pipes and the ability to resist radial deformation of them effectively, glass fiber reinforced plastic pipes with pure hoop winding ply have better long-term mechanical performances. The test data when the time is 8 313.2 h indicates that the proposed prediction model for stiffness degradation rate of glass fiber reinforced plastic pipes has relatively high precision and relatively great applicability.
2016, 33(11): 2500-2509.
doi: 10.13801/j.cnki.fhclxb.20160307.002
Abstract:
In order to investigate the effects of "ex-situ" toughened on the structural bearing capacities of composite stiffened panels, three point bending tests were conducted on composite omega stiffened panels without "ex-situ" toughen and with "ex-situ" toughen firstly, and the initial debonding load, critical failure load and the phenomenon of tests for the two kinds of stiffened panels were compared. Then, three-dimensional progressive failure model was established using ABAQUS, and the mechanisms of interface delamination and the failure process of the skins were analyzed considering the failure of stringer-skin interface and laminated composite plates. The results show that the finite element results coincides well with the test results, "ex-situ" toughen can only improve the initial debonding load of the interface slightly, but has relatively obvious improvement on critical failure load. At the beginning stage of delamination, the type I tensile mode plays a major role. With the delamination expanding continuously, the proportion of type II shear mode increases constantly, while the high toughness of shear mode is the significant cause for the outstanding performances of "ex-situ" toughened interface. The conclusions obtained show that "ex-situ" toughened interface has favorable delaminating resistance, and the behaviour on shear direction is particularly outstanding.
In order to investigate the effects of "ex-situ" toughened on the structural bearing capacities of composite stiffened panels, three point bending tests were conducted on composite omega stiffened panels without "ex-situ" toughen and with "ex-situ" toughen firstly, and the initial debonding load, critical failure load and the phenomenon of tests for the two kinds of stiffened panels were compared. Then, three-dimensional progressive failure model was established using ABAQUS, and the mechanisms of interface delamination and the failure process of the skins were analyzed considering the failure of stringer-skin interface and laminated composite plates. The results show that the finite element results coincides well with the test results, "ex-situ" toughen can only improve the initial debonding load of the interface slightly, but has relatively obvious improvement on critical failure load. At the beginning stage of delamination, the type I tensile mode plays a major role. With the delamination expanding continuously, the proportion of type II shear mode increases constantly, while the high toughness of shear mode is the significant cause for the outstanding performances of "ex-situ" toughened interface. The conclusions obtained show that "ex-situ" toughened interface has favorable delaminating resistance, and the behaviour on shear direction is particularly outstanding.
2016, 33(11): 2510-2516.
doi: 10.13801/j.cnki.fhclxb.20160315.013
Abstract:
In order to improve elastic constants ultrasonic characterization accuracy for unidirectional carbon fiber reinforced plastic (CFRP) plates, experimental measurement and numerical simulation were conducted based on back reflection ultrasonic immersion technique. A single-axis rotation testing setup was developed firstly, and the delay time measurements and ultrasonic velocity calculations at different angles were realized by combining cross-correlation signal processing method. Then, the five independent elastic constants were obtained by the inversion of ultrasonic velocity data using simulated annealing optimization algorithm. Finally, the experimental measurement results were verified by theoretical calculation and CIVA software simulation. The results indicate that the ultrasonic velocities of quasi-longitudinal wave and quasi-transverse wave varied with incident angle in 1-3 plane, which is observably distinct from that of 1-2 plane, thus shows that the material is transversely isotropic. The independent elastic constants are 12.88, 6.39, 126.83, 4.85, 2.97 GPa, respectively. The deviations for ultrasonic velocities of theoretical calculation, CIVA software simulation and experimental measurement results are below 6.4 m/s, the fluctuation of experimental measurement data is below 0.33%, and the corresponding errors of elastic constants are below 0.47%. The methods concerned are also valid for the testing of elastic constants for other orthotropic media.
In order to improve elastic constants ultrasonic characterization accuracy for unidirectional carbon fiber reinforced plastic (CFRP) plates, experimental measurement and numerical simulation were conducted based on back reflection ultrasonic immersion technique. A single-axis rotation testing setup was developed firstly, and the delay time measurements and ultrasonic velocity calculations at different angles were realized by combining cross-correlation signal processing method. Then, the five independent elastic constants were obtained by the inversion of ultrasonic velocity data using simulated annealing optimization algorithm. Finally, the experimental measurement results were verified by theoretical calculation and CIVA software simulation. The results indicate that the ultrasonic velocities of quasi-longitudinal wave and quasi-transverse wave varied with incident angle in 1-3 plane, which is observably distinct from that of 1-2 plane, thus shows that the material is transversely isotropic. The independent elastic constants are 12.88, 6.39, 126.83, 4.85, 2.97 GPa, respectively. The deviations for ultrasonic velocities of theoretical calculation, CIVA software simulation and experimental measurement results are below 6.4 m/s, the fluctuation of experimental measurement data is below 0.33%, and the corresponding errors of elastic constants are below 0.47%. The methods concerned are also valid for the testing of elastic constants for other orthotropic media.
2016, 33(11): 2517-2527.
doi: 10.13801/j.cnki.fhclxb.20160308.003
Abstract:
The mechanical properties of T800/924 composite joints under tensile loading were studied by means of test and simulation analysis. The tensile test of the joint specimen was carried out on the electronic universal testing machine. The failure process of the specimen was recorded during the test and the final failure load was obtained. A nonlinear finite element method was used, based on the ABAQUS software platform, using the embedded material user defined subroutine (VUMAT). The finite element analysis model for the test was established to obtain the strain distribution of the joint, and the calculated value of the joint failure load was given. The results show that the calculation prediction of the damage parts for the joint are in agreement with the test. The difference values between calculated value and test value of the failure load are small. The feasibility of the simulation analysis method is proved. The results analysis show that hole edge is where the stress concentrated. The damage is usually initiated from hole edge and the ability of out-of -plane loaded of joint is poor. Failure mode of joint is generally the pull-out of hole edge surface.
The mechanical properties of T800/924 composite joints under tensile loading were studied by means of test and simulation analysis. The tensile test of the joint specimen was carried out on the electronic universal testing machine. The failure process of the specimen was recorded during the test and the final failure load was obtained. A nonlinear finite element method was used, based on the ABAQUS software platform, using the embedded material user defined subroutine (VUMAT). The finite element analysis model for the test was established to obtain the strain distribution of the joint, and the calculated value of the joint failure load was given. The results show that the calculation prediction of the damage parts for the joint are in agreement with the test. The difference values between calculated value and test value of the failure load are small. The feasibility of the simulation analysis method is proved. The results analysis show that hole edge is where the stress concentrated. The damage is usually initiated from hole edge and the ability of out-of -plane loaded of joint is poor. Failure mode of joint is generally the pull-out of hole edge surface.
2016, 33(11): 2528-2536.
doi: 10.13801/j.cnki.fhclxb.20160315.015
Abstract:
Macro mechanical behavior of Al particles reinforced polytetrafluoroethylene(Al/PTFE) was studied by finite element method. According to statistics on Al particles and microvoids by SEM, representative volume element (RVE) models considering particles and microvoids distribution as well as geometry were reproduced. By using ABAQUS finite element software, mechanical behavior under uniaxial compression of both two dimension and three dimension models were simulated. Also periodic boundary condition (PBC) was applied to improve accuracy of calculation. Quasistatic stress-strain curves of composites of various particle fractions were analyzed, and especially results from simulations and experiments were compared. The results indicate that both two dimension and three dimension models are effective methods to predict the mechanical behavior of Al/PTFE, and two dimension models are more efficient. Furthermore, the validity and effectiveness of the PBC are verified.
Macro mechanical behavior of Al particles reinforced polytetrafluoroethylene(Al/PTFE) was studied by finite element method. According to statistics on Al particles and microvoids by SEM, representative volume element (RVE) models considering particles and microvoids distribution as well as geometry were reproduced. By using ABAQUS finite element software, mechanical behavior under uniaxial compression of both two dimension and three dimension models were simulated. Also periodic boundary condition (PBC) was applied to improve accuracy of calculation. Quasistatic stress-strain curves of composites of various particle fractions were analyzed, and especially results from simulations and experiments were compared. The results indicate that both two dimension and three dimension models are effective methods to predict the mechanical behavior of Al/PTFE, and two dimension models are more efficient. Furthermore, the validity and effectiveness of the PBC are verified.
2016, 33(11): 2537-2542.
doi: 10.13801/j.cnki.fhclxb.20160309.001
Abstract:
Fiber bragg grating (FBG) sensor is usually pasted on the substrate to measure the surface strain, so it can achieve the compatibility of deformation. But different adhesive show various property on different substrate, thus influence the strain measurement result. In response to this problem, an experiment was conducted to simply the strain transfer model. The strain result measured by FBG sensor pasted on the beam of uniform strength and the standard resin specimen was compared. The results show that the greater the shear strength of the adhesive on the substrate, the strain transfer coefficient of surface-bonded FBG sensor is better.
Fiber bragg grating (FBG) sensor is usually pasted on the substrate to measure the surface strain, so it can achieve the compatibility of deformation. But different adhesive show various property on different substrate, thus influence the strain measurement result. In response to this problem, an experiment was conducted to simply the strain transfer model. The strain result measured by FBG sensor pasted on the beam of uniform strength and the standard resin specimen was compared. The results show that the greater the shear strength of the adhesive on the substrate, the strain transfer coefficient of surface-bonded FBG sensor is better.
2016, 33(11): 2543-2550.
doi: 10.13801/j.cnki.fhclxb.20160219.003
Abstract:
The elastic constants of airship envelope material are the basic for the shape design, structural analysis and dynamics analysis of airship. In this paper, a method of biaxial tensile test was carried out to obtain the elastic-modulus and Poisson's ratio of warp and weft respectively of airship envelope material HV130 under different differential pressure according to the assumption of orthogonal planar stress model. The theoretical results of stress for envelope and the loading ratio of hoop and longitudinal stress were established by stress analysis of airship envelope. Then based on the stress ratio of the airship, the corresponding elastic constants were selected from the biaxial tensile test and were applied to establish static simulation analysis for envelope under differential pressure. A non-contact strain measurement system was conducted to measure the strain of the envelope under differential pressure and verified the reliability of the finite element modal and the accuracy of elastic constants obtained by the biaxial tensile test. This paper can provide a reference for the shape design and structural analysis of airship.
The elastic constants of airship envelope material are the basic for the shape design, structural analysis and dynamics analysis of airship. In this paper, a method of biaxial tensile test was carried out to obtain the elastic-modulus and Poisson's ratio of warp and weft respectively of airship envelope material HV130 under different differential pressure according to the assumption of orthogonal planar stress model. The theoretical results of stress for envelope and the loading ratio of hoop and longitudinal stress were established by stress analysis of airship envelope. Then based on the stress ratio of the airship, the corresponding elastic constants were selected from the biaxial tensile test and were applied to establish static simulation analysis for envelope under differential pressure. A non-contact strain measurement system was conducted to measure the strain of the envelope under differential pressure and verified the reliability of the finite element modal and the accuracy of elastic constants obtained by the biaxial tensile test. This paper can provide a reference for the shape design and structural analysis of airship.
2016, 33(11): 2551-2559.
doi: 10.13801/j.cnki.fhclxb.20160304.001
Abstract:
For the traditional continuous bending and roller leveling theory was created upon the repeated and continuous bending deformation of single metal, so when the theory was applied to the continuous bending and leveling of double metal composite plates, the precision is not high and the leveled flatness of double metal composite plates cannot be guaranteed. In order to perfect the theory of plate straightening force, the characteristics of double metal composite plate in leveling and bending deformation were analyzed, and hierarchical algorithm was proposed, and the model calculated data was compared with straightening experiment data. The results show that the method proposed can adopt different calculation methods and material models in different metal deformation layers, and is suitable to solve the roller leveling problems of double metal composite plates. The model calculated straightening force error is no more than 5.73%. The conclusions obtained show that using mathematical model based on hierarchical algorithm can achieve good results in the calculation of double metal composite plates.
For the traditional continuous bending and roller leveling theory was created upon the repeated and continuous bending deformation of single metal, so when the theory was applied to the continuous bending and leveling of double metal composite plates, the precision is not high and the leveled flatness of double metal composite plates cannot be guaranteed. In order to perfect the theory of plate straightening force, the characteristics of double metal composite plate in leveling and bending deformation were analyzed, and hierarchical algorithm was proposed, and the model calculated data was compared with straightening experiment data. The results show that the method proposed can adopt different calculation methods and material models in different metal deformation layers, and is suitable to solve the roller leveling problems of double metal composite plates. The model calculated straightening force error is no more than 5.73%. The conclusions obtained show that using mathematical model based on hierarchical algorithm can achieve good results in the calculation of double metal composite plates.
2016, 33(11): 2560-2568.
doi: 10.13801/j.cnki.fhclxb.20160104.001
Abstract:
In order to investigate the effects of WC volume fraction on microstructures, interfaces and compression performances of WCp/Fe composites, WCp/Fe composites with different WC volume fractions were prepared by power sintering method. The results show that WC particles have different degrees of dissolution in WCp/Fe composites with different WC volume fractions, and show metallurgical bond with the matrix. With the increase of WC volume fraction, the interface equivalent widths of WCp/Fe composites exhibit decreasing trend, and when the WC volume fraction is 50%, the interface equivalent width is the smallest, which is 39.8 μm. The compressive strengths of the composites exhibit the trend of increasing firstly and then decreasing, and when WC volume fraction reaches 45%, compression strength reaches the maximum. The fracture modes of the composites transform from quasi-cleavage fracture to pure cleavage fracture, and when WC volume fraction reaches 50%, the fracture mode of WCp/Fe composite is pure cleavage fracture.
In order to investigate the effects of WC volume fraction on microstructures, interfaces and compression performances of WCp/Fe composites, WCp/Fe composites with different WC volume fractions were prepared by power sintering method. The results show that WC particles have different degrees of dissolution in WCp/Fe composites with different WC volume fractions, and show metallurgical bond with the matrix. With the increase of WC volume fraction, the interface equivalent widths of WCp/Fe composites exhibit decreasing trend, and when the WC volume fraction is 50%, the interface equivalent width is the smallest, which is 39.8 μm. The compressive strengths of the composites exhibit the trend of increasing firstly and then decreasing, and when WC volume fraction reaches 45%, compression strength reaches the maximum. The fracture modes of the composites transform from quasi-cleavage fracture to pure cleavage fracture, and when WC volume fraction reaches 50%, the fracture mode of WCp/Fe composite is pure cleavage fracture.
2016, 33(11): 2569-2575.
doi: 10.13801/j.cnki.fhclxb.20160107.005
Abstract:
The effect of Cl- concentration on the electrochemical corrosion behavior of SiCP/Al composites was inverstigated by using immersion test, electrochemical polarization and electrochemical impedance spectroscopy test technique. The results show that passivation is not obvious of SiCP/Al composites in Cl- medium and the corrosion process is mainly pitting corrosion. With increasing of Cl- concentration, the corrosion rate of SiCP/Al composites increases, the pitting potential decreases, and the corrosion mechanism of the composites presents the characteristics of transfering from a unique charge transfer process mechanism to a mixed mechanism control of charge transfer process and corrosion production diffusion. Electrochemical impedance spectroscopy exhibits two type with increasing of Cl- concentration:a unique capacitance arcs type and a mixed type including a capacitance arcs in high frequency region and a straight line with the real axis of 45° (classics Warburg resistance) in low frequency.
The effect of Cl- concentration on the electrochemical corrosion behavior of SiCP/Al composites was inverstigated by using immersion test, electrochemical polarization and electrochemical impedance spectroscopy test technique. The results show that passivation is not obvious of SiCP/Al composites in Cl- medium and the corrosion process is mainly pitting corrosion. With increasing of Cl- concentration, the corrosion rate of SiCP/Al composites increases, the pitting potential decreases, and the corrosion mechanism of the composites presents the characteristics of transfering from a unique charge transfer process mechanism to a mixed mechanism control of charge transfer process and corrosion production diffusion. Electrochemical impedance spectroscopy exhibits two type with increasing of Cl- concentration:a unique capacitance arcs type and a mixed type including a capacitance arcs in high frequency region and a straight line with the real axis of 45° (classics Warburg resistance) in low frequency.
2016, 33(11): 2576-2583.
doi: 10.13801/j.cnki.fhclxb.20160302.002
Abstract:
The effects of Ca content on SiC dispersity in SiC reinforced aluminum matrix(SiC/Al) composites, and the effects of Ca content on the compressive property as well as the structure of SiC/Al foam composites prepared by gas injection method were investigated. Firstly, the SiC/Al composites with different Ca contents were prepared as base materials for the fabrication of SiC/Al foam composites, and the compressive test was conducted to the SiC/Al foam composites with different Ca contents. Then the effects of Ca content on SiC dispersity in the SiC/Al composites and foam structure were analyzed using OM, SEM and XRD. The results show that the addition of Ca can obviously affect the SiC distribution in the SiC/Al composites and there is a critical value of Ca content. SiC distributes uniformly in matrix when Ca content is smaller than 1.5wt%. Intermetallic compounds Ca2Al4Si3 which are rich of Al, Ca and Si form in the melt when Ca content reaches or exceeds 1.5wt%. Their volume fraction and size increase obviously with the increasing of Ca content, which leads to the aggregation of SiC in these intermetallic compounds and their boundaries, affecting the uniformity of SiC distribution. The compressive test reveals that the plateau stress and the compressive yield strength of the compressive stress-strain curves for SiC/Al foam composites have an increasing tendency with Ca content increasing. The corresponding cell wall thickness of SiC/Al foam composites also increases obviously with the increasing of Ca content. It is not only related to the melt viscosity improved by the formation of intermetallic compounds, but more likely related to the size of intermetallic compounds in the melt increasing with the increasing of Ca content.
The effects of Ca content on SiC dispersity in SiC reinforced aluminum matrix(SiC/Al) composites, and the effects of Ca content on the compressive property as well as the structure of SiC/Al foam composites prepared by gas injection method were investigated. Firstly, the SiC/Al composites with different Ca contents were prepared as base materials for the fabrication of SiC/Al foam composites, and the compressive test was conducted to the SiC/Al foam composites with different Ca contents. Then the effects of Ca content on SiC dispersity in the SiC/Al composites and foam structure were analyzed using OM, SEM and XRD. The results show that the addition of Ca can obviously affect the SiC distribution in the SiC/Al composites and there is a critical value of Ca content. SiC distributes uniformly in matrix when Ca content is smaller than 1.5wt%. Intermetallic compounds Ca2Al4Si3 which are rich of Al, Ca and Si form in the melt when Ca content reaches or exceeds 1.5wt%. Their volume fraction and size increase obviously with the increasing of Ca content, which leads to the aggregation of SiC in these intermetallic compounds and their boundaries, affecting the uniformity of SiC distribution. The compressive test reveals that the plateau stress and the compressive yield strength of the compressive stress-strain curves for SiC/Al foam composites have an increasing tendency with Ca content increasing. The corresponding cell wall thickness of SiC/Al foam composites also increases obviously with the increasing of Ca content. It is not only related to the melt viscosity improved by the formation of intermetallic compounds, but more likely related to the size of intermetallic compounds in the melt increasing with the increasing of Ca content.
2016, 33(11): 2584-2590.
doi: 10.13801/j.cnki.fhclxb.20160108.003
Abstract:
Friction and wear properties of WC-Al2O3 composite, which slid against WC-6Co, were studied by slide friction and wear experiment of spherical surface contact friction mode on HT-1000 high-temperature friction and wear test instrument within the temperature range of 25℃ to 600℃. In additional, a comparison of WC-Al2O3 and WC-6Co was conducted. The micro morphologies of the worn surface and surface composition of the materials were analyzed by SEM, and ultra-depth microscope and XRD. The results show that the friction coefficient of WC-Al2O3 composite is smaller and the friction and wear property is better at room temperature. When the temperature increases to 600℃, the oxide formation is accelerated on the surface of WC-Al2O3 composite grinding marks, the friction coefficient decreases remarkably. At the same time, wear mechanism change to oxidation wear from abrasive wear, also friction and wear properties are slightly worse.
Friction and wear properties of WC-Al2O3 composite, which slid against WC-6Co, were studied by slide friction and wear experiment of spherical surface contact friction mode on HT-1000 high-temperature friction and wear test instrument within the temperature range of 25℃ to 600℃. In additional, a comparison of WC-Al2O3 and WC-6Co was conducted. The micro morphologies of the worn surface and surface composition of the materials were analyzed by SEM, and ultra-depth microscope and XRD. The results show that the friction coefficient of WC-Al2O3 composite is smaller and the friction and wear property is better at room temperature. When the temperature increases to 600℃, the oxide formation is accelerated on the surface of WC-Al2O3 composite grinding marks, the friction coefficient decreases remarkably. At the same time, wear mechanism change to oxidation wear from abrasive wear, also friction and wear properties are slightly worse.
2016, 33(11): 2591-2599.
doi: 10.13801/j.cnki.fhclxb.20160125.003
Abstract:
In order to improve water quality through filtering microbial and impurities in water, Ag doped hydroxyapatite (Ag-HA) antibacterial powders were prepared by one-step-coprecipitation method, and they were mixed with raw materials such as diatomite and kaolin etc. to prepare Ag-HA/diatomite-kaolin composite ceramics by sintering method firstly. Then, the structures of Ag-HA/diatomite-kaolin composite ceramics were characterized by XRD, SEM, EDS and atomic absorption spectrophotometer. Finally, the antibacterial properties of Ag-HA/diatomite-kaolin composite ceramics for Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus) were investigated. The results show that the main phases of Ag-HA/diatomite-kaolin composite ceramics are quartz, cristobalite and HA. Ag-HA/diatomite-kaolin composite ceramics contain numerous channels after high-heat sintering, which are made up of the micron scale pores between diatomite particles and the pores in particles; microcrystalline Ag distributes uniformly in Ag-HA/diatomite-kaolin composite ceramics. When Ag content is 0.098wt%, the minimal inhibitory concentrations against E.coli and S.aureus are 100 μg/mL and 50 μg/mL respectively. Bactericidal rates of block or powdery Ag-HA/diatomite-kaolin composite ceramics against E.coli and S.aureus are 60.76% and 100.00% within 1 h, both reach 100.00% after 3 h, and possess persistent antibacterial properties within 24 h. The conclusions obtained indicate that the prepared Ag-HA/diatomite-kaolin composite ceramics are a promising filter for water treatment.
In order to improve water quality through filtering microbial and impurities in water, Ag doped hydroxyapatite (Ag-HA) antibacterial powders were prepared by one-step-coprecipitation method, and they were mixed with raw materials such as diatomite and kaolin etc. to prepare Ag-HA/diatomite-kaolin composite ceramics by sintering method firstly. Then, the structures of Ag-HA/diatomite-kaolin composite ceramics were characterized by XRD, SEM, EDS and atomic absorption spectrophotometer. Finally, the antibacterial properties of Ag-HA/diatomite-kaolin composite ceramics for Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus) were investigated. The results show that the main phases of Ag-HA/diatomite-kaolin composite ceramics are quartz, cristobalite and HA. Ag-HA/diatomite-kaolin composite ceramics contain numerous channels after high-heat sintering, which are made up of the micron scale pores between diatomite particles and the pores in particles; microcrystalline Ag distributes uniformly in Ag-HA/diatomite-kaolin composite ceramics. When Ag content is 0.098wt%, the minimal inhibitory concentrations against E.coli and S.aureus are 100 μg/mL and 50 μg/mL respectively. Bactericidal rates of block or powdery Ag-HA/diatomite-kaolin composite ceramics against E.coli and S.aureus are 60.76% and 100.00% within 1 h, both reach 100.00% after 3 h, and possess persistent antibacterial properties within 24 h. The conclusions obtained indicate that the prepared Ag-HA/diatomite-kaolin composite ceramics are a promising filter for water treatment.
2016, 33(11): 2600-2608.
doi: 10.13801/j.cnki.fhclxb.20160229.001
Abstract:
The laminated composites of TiB2 based ceramic-42CrMo alloy steel were rapidly prepared by self-propagating high-temperature synthesis centrifugal-casting process, and the span-scale continuously-graded composite structures of three dimensional-network TiB2 matrix ceramic/Fe-Ni alloy developed on the interface between the layers, leading to the laminated composite with 3-layer structure consisting of ceramic matrix, the intermediate and alloy steel matrix. Combining mechanical properties test with FESEM and HETEM examination, it is considered that the in-situ achievement of the continuously-graded composite structure of three dimensional-network span-scale TiB2 matrix ceramic/Fe-Ni alloy in interlaminar interface not only presents the laminated composite with high flexural strength and high fracture toughness, but also presents the composite with the mechanic behavior of bogus plasticity when the three point bending test conducts. Meanwhile, the cooperative action of crack interlocking by TiB2 matrix ceramic/Fe-Ni based alloy composite structure nearby the ceramic matrix with precipitation strengthening by micro-nanometer or nanometer TiB2 platelets in the intermediate also presents the laminated composite of TiB2 based ceramic-42CrMo alloy steel with high interlaminar shear strength.
The laminated composites of TiB2 based ceramic-42CrMo alloy steel were rapidly prepared by self-propagating high-temperature synthesis centrifugal-casting process, and the span-scale continuously-graded composite structures of three dimensional-network TiB2 matrix ceramic/Fe-Ni alloy developed on the interface between the layers, leading to the laminated composite with 3-layer structure consisting of ceramic matrix, the intermediate and alloy steel matrix. Combining mechanical properties test with FESEM and HETEM examination, it is considered that the in-situ achievement of the continuously-graded composite structure of three dimensional-network span-scale TiB2 matrix ceramic/Fe-Ni alloy in interlaminar interface not only presents the laminated composite with high flexural strength and high fracture toughness, but also presents the composite with the mechanic behavior of bogus plasticity when the three point bending test conducts. Meanwhile, the cooperative action of crack interlocking by TiB2 matrix ceramic/Fe-Ni based alloy composite structure nearby the ceramic matrix with precipitation strengthening by micro-nanometer or nanometer TiB2 platelets in the intermediate also presents the laminated composite of TiB2 based ceramic-42CrMo alloy steel with high interlaminar shear strength.
2016, 33(11): 2609-2617.
doi: 10.13801/j.cnki.fhclxb.20160126.001
Abstract:
In order to analyze the deposition mechanism of carbon source during the chemical vapor infiltration process, using carbon fiber neddled flet as preform, propylene (C3H6) added natural gas mixture gas as carbon source, the effects of carbon source composition on densification of C/C composites and microstructure of pyrolytic carbon were investigated. The results show that compared with using natural gas as carbon source, using a moderate ratio of C3H6 added natural gas as carbon source can improve the densification efficiency and density distribution uniformity of C/C composites effectively. At the same time, it is beneficial to form high texture pyrolytic carbon. After deposition for 100 h under the optimal condition (9vol% C3H6), the density and density deviation at radial direction of C/C composites are 1.40 g/cm3 and 0.04 g/cm3 respectively, the pyrolytic carbon is homogeneous rough laminar structure, and the graphitization degree is high. While when using natural gas as carbon source, the density and density deviation at radial direction are 1.17 g/cm3 and 0.07 g/cm3 respectively, the pyrolytic carbon is binary banded structure, and the graphitization degree is lower. When the ratio of C3H6 is improved to 17vol%, the density and density deviation at radial direction of it are 1.28 g/cm3 and 0.10 g/cm3 respectively. Compared to the composite prepared under the optimal condition, the density and density distribution uniformity decrease obviously.
In order to analyze the deposition mechanism of carbon source during the chemical vapor infiltration process, using carbon fiber neddled flet as preform, propylene (C3H6) added natural gas mixture gas as carbon source, the effects of carbon source composition on densification of C/C composites and microstructure of pyrolytic carbon were investigated. The results show that compared with using natural gas as carbon source, using a moderate ratio of C3H6 added natural gas as carbon source can improve the densification efficiency and density distribution uniformity of C/C composites effectively. At the same time, it is beneficial to form high texture pyrolytic carbon. After deposition for 100 h under the optimal condition (9vol% C3H6), the density and density deviation at radial direction of C/C composites are 1.40 g/cm3 and 0.04 g/cm3 respectively, the pyrolytic carbon is homogeneous rough laminar structure, and the graphitization degree is high. While when using natural gas as carbon source, the density and density deviation at radial direction are 1.17 g/cm3 and 0.07 g/cm3 respectively, the pyrolytic carbon is binary banded structure, and the graphitization degree is lower. When the ratio of C3H6 is improved to 17vol%, the density and density deviation at radial direction of it are 1.28 g/cm3 and 0.10 g/cm3 respectively. Compared to the composite prepared under the optimal condition, the density and density distribution uniformity decrease obviously.
2016, 33(11): 2618-2624.
doi: 10.13801/j.cnki.fhclxb.20151223.002
Abstract:
In order to investigate the effects of reductants on structures and electrochemical performances of Ni(OH)2/reduced graphene oxide (RGO) composites, Ni(OH)2/RGO composites were synthesized using graphite oxide (GO) and nickel nitrate as precursors by hydrothermal method firstly. Then, the structures and morphologies of the composites were characterized using XRD, SEM and Raman spectrometer, and the electrochemical performances were investigated using cyclic voltammetry, galvanostatic charge-discharge curves and electrochemical impedance spectroscopy. The results show that when using (NH2)2CSO2 as reductant, the synthesized β-Ni(OH)2/RGO composite has mutually embedded structure of RGO nanosheets and Ni(OH)2 nanosheets. The specific capacity of the β-Ni(OH)2/RGO composite is 341.0 mAh/g in electrolyte (6 mol/L KOH solution) at discharge rate of 0.2C. The specific capacity of the composite is 242.2 mAh/g at discharge rate of 10.0C rate, which still maintains 83.8% of theoretical specific capacity for β-Ni(OH)2. The conclusions obtained show that the synthesized Ni(OH)2/RGO composites show excellent electrochemical performances.
In order to investigate the effects of reductants on structures and electrochemical performances of Ni(OH)2/reduced graphene oxide (RGO) composites, Ni(OH)2/RGO composites were synthesized using graphite oxide (GO) and nickel nitrate as precursors by hydrothermal method firstly. Then, the structures and morphologies of the composites were characterized using XRD, SEM and Raman spectrometer, and the electrochemical performances were investigated using cyclic voltammetry, galvanostatic charge-discharge curves and electrochemical impedance spectroscopy. The results show that when using (NH2)2CSO2 as reductant, the synthesized β-Ni(OH)2/RGO composite has mutually embedded structure of RGO nanosheets and Ni(OH)2 nanosheets. The specific capacity of the β-Ni(OH)2/RGO composite is 341.0 mAh/g in electrolyte (6 mol/L KOH solution) at discharge rate of 0.2C. The specific capacity of the composite is 242.2 mAh/g at discharge rate of 10.0C rate, which still maintains 83.8% of theoretical specific capacity for β-Ni(OH)2. The conclusions obtained show that the synthesized Ni(OH)2/RGO composites show excellent electrochemical performances.
2016, 33(11): 2625-2633.
doi: 10.13801/j.cnki.fhclxb.20160107.007
Abstract:
In order to compare mechanical properties and moisture absorption properties of wheat straw/biological glue composites prepared by the biological glues (sodium alginate, guar gum, starch gum, plant protein adhesive) and wheat straw, infrared spectra of four kinds of biological glues and wheat straw were analyzed, mechanical properties and moisture absorption properties of wheat straw/biological glue composites were tested, and their microstructure were observed. The results show that four kinds of biological glues have stretching vibration absorption peaks of -CH and -OH, plant protein adhesive has stretching vibration absorption peak of -NH2 and absorption peak of -O-. The mechanical properties of the composites prepared by plant protein adhesive are good, and moisture absorption rate is small. The tensile strength of composites prepared by plant protein glue is 436%, 93%, 416% higher than that of composites prepared by sodium alginate, guar gum and starch gum, the bending strength is 922%, 49%, 963% higher, the elastic modulus is 714%, 678%, 254% higher, and the absorption rate is 42%, 17%, 16% smaller, respectively. Wheat straw are wrapped preferably by matrix in wheat straw/plant protein adhesive and wheat straw/guar gum composites, and the two phase interface between plant protein adhesive-wheat straw and guar gum-wheat straw are fuzzy, which combine well. However, wheat straw/sodium alginate and wheat straw/starch gum composites have more holes and flaws in the two phase interface. The interface between wheat straw and matrix is obvious, the combination with wheat straw is worse. Wheat straw/plant protein adhesive composites are equivalent to the plastic-based composites in mechanical properties, but the moisture absorption property needs to be improved.
In order to compare mechanical properties and moisture absorption properties of wheat straw/biological glue composites prepared by the biological glues (sodium alginate, guar gum, starch gum, plant protein adhesive) and wheat straw, infrared spectra of four kinds of biological glues and wheat straw were analyzed, mechanical properties and moisture absorption properties of wheat straw/biological glue composites were tested, and their microstructure were observed. The results show that four kinds of biological glues have stretching vibration absorption peaks of -CH and -OH, plant protein adhesive has stretching vibration absorption peak of -NH2 and absorption peak of -O-. The mechanical properties of the composites prepared by plant protein adhesive are good, and moisture absorption rate is small. The tensile strength of composites prepared by plant protein glue is 436%, 93%, 416% higher than that of composites prepared by sodium alginate, guar gum and starch gum, the bending strength is 922%, 49%, 963% higher, the elastic modulus is 714%, 678%, 254% higher, and the absorption rate is 42%, 17%, 16% smaller, respectively. Wheat straw are wrapped preferably by matrix in wheat straw/plant protein adhesive and wheat straw/guar gum composites, and the two phase interface between plant protein adhesive-wheat straw and guar gum-wheat straw are fuzzy, which combine well. However, wheat straw/sodium alginate and wheat straw/starch gum composites have more holes and flaws in the two phase interface. The interface between wheat straw and matrix is obvious, the combination with wheat straw is worse. Wheat straw/plant protein adhesive composites are equivalent to the plastic-based composites in mechanical properties, but the moisture absorption property needs to be improved.
2016, 33(11): 2634-2640.
doi: 10.13801/j.cnki.fhclxb.20160112.001
Abstract:
Based on the acid-alkali method to extract feather keratin in duck feather, the optimum conditions for extraction of feather keratin were studied by orthogonal experiment.The feather keratin and sodium alginate were mixed to prepare sodium alginate/feather keratin (SA/FK) composite solution and the rheology of solution was tested. The SA/FK composite fibers were prepared by wet spinning. The basic properties of composite fibers were studied and the intermolecular hydrogen bondsof composite fibers were characterized. The results show that under the optimum extracting condition (the temperature is 60.0℃, the reaction time is 120.00 min, alkali concentration is 2.00wt%), the feather keratin presents the largest production rate of 45.75%. The apparent viscosity of the SA/FK composite solution decreases with the increasing of shear rate and increases first and then decreases with the increasing of the feather keratin content. The addition of feather keratin enhances the intermolecular hydrogen bonds. The fracture strength of SA/FK composite fiber can reach 1.96 cN/dtex. The recombination of sodium alginate and the feather keratin damage the crystalline structure of the original molecule. The molecular structure of SA/FK composite fibers exist as amorphousstate. The surface of SA/FK composite fibers have a uniform trench structure.
Based on the acid-alkali method to extract feather keratin in duck feather, the optimum conditions for extraction of feather keratin were studied by orthogonal experiment.The feather keratin and sodium alginate were mixed to prepare sodium alginate/feather keratin (SA/FK) composite solution and the rheology of solution was tested. The SA/FK composite fibers were prepared by wet spinning. The basic properties of composite fibers were studied and the intermolecular hydrogen bondsof composite fibers were characterized. The results show that under the optimum extracting condition (the temperature is 60.0℃, the reaction time is 120.00 min, alkali concentration is 2.00wt%), the feather keratin presents the largest production rate of 45.75%. The apparent viscosity of the SA/FK composite solution decreases with the increasing of shear rate and increases first and then decreases with the increasing of the feather keratin content. The addition of feather keratin enhances the intermolecular hydrogen bonds. The fracture strength of SA/FK composite fiber can reach 1.96 cN/dtex. The recombination of sodium alginate and the feather keratin damage the crystalline structure of the original molecule. The molecular structure of SA/FK composite fibers exist as amorphousstate. The surface of SA/FK composite fibers have a uniform trench structure.
2016, 33(11): 2641-2648.
doi: 10.13801/j.cnki.fhclxb.20160411.007
Abstract:
In this work, the tetrahedral unit cell model, which was suitable for low-density foam, was modified to predict the creep properties of foam materials in a broader range of density varieties, by considering the volume correction at the intersection point of struts. The influences of the bending and shearing deformation mechanisms of the inclined struts on the creep strain rate were investigated based on the modified model. The results indicate that the bending deformation mechanism of struts dominates the creep rate of the foam with a relative low density, and the shearing deformation mechanism dominates the creep rate of the foam with a relative high density. A comparison with the experiment results verified the predictions of the present work.
In this work, the tetrahedral unit cell model, which was suitable for low-density foam, was modified to predict the creep properties of foam materials in a broader range of density varieties, by considering the volume correction at the intersection point of struts. The influences of the bending and shearing deformation mechanisms of the inclined struts on the creep strain rate were investigated based on the modified model. The results indicate that the bending deformation mechanism of struts dominates the creep rate of the foam with a relative low density, and the shearing deformation mechanism dominates the creep rate of the foam with a relative high density. A comparison with the experiment results verified the predictions of the present work.
2016, 33(11): 2649-2656.
doi: 10.13801/j.cnki.fhclxb.20160229.004
Abstract:
Hydroxyl Fe intercalated bentonite (OH-Fe-Bent) was prepared by Na-bentonite while using hydroxyl Fe as intercalated material. The synthesized OH-Fe-Bent composites applied to adsorb U(VI) from water solution. The effects of pH value, initial U(VI) concentration, temperature and contact time on adsorption of U(VI) for OH-Fe-Bent were experimentally determined, and the process of adsorption was investigated by kinetic and thermodynamic analysis. The corresponding adsorption mechanisms were analyzed by FTIR, SEM, and XRD etc. The experimental results indicate that the maximum adsorption capacity occurs at pH 4 and the removal rate of U(VI) for OH-Fe-Bent reaches 99.55% for initial U(VI) concentration of 10 mg/L and adsorbent dosage of 0.8 g/L at 15℃. Meanwhile the adsorption reaches equilibrium within 90 min. The adsorption process fits well with the Langmuir isotherm adsorption model and pseudo second-order kinetic model (square of correlation coefficient is about 1), and the theoretical saturated adsorption capacity is 97.09 mg/g, adsorption mechanism of U(VI) for OH-Fe-Bent is a monolayer adsorption. The FTIR and SEM analyses show that the structure of OH-Fe-Bent has no change after absorbing U(VI) and the XRD analysis shows that the hydroxyl Fe has already intercalated bentonite.
Hydroxyl Fe intercalated bentonite (OH-Fe-Bent) was prepared by Na-bentonite while using hydroxyl Fe as intercalated material. The synthesized OH-Fe-Bent composites applied to adsorb U(VI) from water solution. The effects of pH value, initial U(VI) concentration, temperature and contact time on adsorption of U(VI) for OH-Fe-Bent were experimentally determined, and the process of adsorption was investigated by kinetic and thermodynamic analysis. The corresponding adsorption mechanisms were analyzed by FTIR, SEM, and XRD etc. The experimental results indicate that the maximum adsorption capacity occurs at pH 4 and the removal rate of U(VI) for OH-Fe-Bent reaches 99.55% for initial U(VI) concentration of 10 mg/L and adsorbent dosage of 0.8 g/L at 15℃. Meanwhile the adsorption reaches equilibrium within 90 min. The adsorption process fits well with the Langmuir isotherm adsorption model and pseudo second-order kinetic model (square of correlation coefficient is about 1), and the theoretical saturated adsorption capacity is 97.09 mg/g, adsorption mechanism of U(VI) for OH-Fe-Bent is a monolayer adsorption. The FTIR and SEM analyses show that the structure of OH-Fe-Bent has no change after absorbing U(VI) and the XRD analysis shows that the hydroxyl Fe has already intercalated bentonite.
2016, 33(11): 2657-2665.
doi: 10.13801/j.cnki.fhclxb.20160311.001
Abstract:
Three kinds of carbon matrix composites (chemical vapor deposition (CVD) prepared C/C composites, CVD/impregnation prepared C/C composites and CVD/molten silicon infiltration (MSI) prepared C/C-SiC composites, respectively) were chosen to study their potential application as new internal fixation materials. The microstructure and mechanical properties of three kinds of carbon matrix composites and human bone were analyzed.The results show that three kinds of carbon matrix composites and human bone have fiber reinforced porous matrix microstructure. As for mechanical property, the elastic modulus of three kinds of carbon matrix composites and human bone are highly similar. C/C-SiC composites is expected to be used as an ideal bone plate material since it has the closest mechanical property compared to human bone, for bending strength of 213.0 MPa, shear strength of 19.3 MPa and compressive strength of 228.1 MPa. Bending strength of C/C composites prepared by CVD and CVD/impregnation is 161.8 MPa and 174.6 MPa, respectively, which are lower than that of human bone. Mechanical properties of C/C composites can be improved by optimization of the preform structure and preparation process in the future.
Three kinds of carbon matrix composites (chemical vapor deposition (CVD) prepared C/C composites, CVD/impregnation prepared C/C composites and CVD/molten silicon infiltration (MSI) prepared C/C-SiC composites, respectively) were chosen to study their potential application as new internal fixation materials. The microstructure and mechanical properties of three kinds of carbon matrix composites and human bone were analyzed.The results show that three kinds of carbon matrix composites and human bone have fiber reinforced porous matrix microstructure. As for mechanical property, the elastic modulus of three kinds of carbon matrix composites and human bone are highly similar. C/C-SiC composites is expected to be used as an ideal bone plate material since it has the closest mechanical property compared to human bone, for bending strength of 213.0 MPa, shear strength of 19.3 MPa and compressive strength of 228.1 MPa. Bending strength of C/C composites prepared by CVD and CVD/impregnation is 161.8 MPa and 174.6 MPa, respectively, which are lower than that of human bone. Mechanical properties of C/C composites can be improved by optimization of the preform structure and preparation process in the future.
2016, 33(11): 2666-2673.
doi: 10.13801/j.cnki.fhclxb.20160414.001
Abstract:
An optimization model of the process parameters during a chemical vapor infiltration (CVI) was established based on genetic algorithm and back propagation (GA-BP) neural network. The experimental data from the novel isothermal CVI process of carbon/carbon (C/C) composites were selected as the samples to evaluate the model. The effect of the main controllable factors, such as infiltration temperature, part pressure of precursor gas and resident time etc, on the density and uniformity of C/C composites were analyzed. Under the guidance of the model, the maximum errors between the desired densities and the tested densities of the experiment samples are not larger than 6.2% and those between their density differences were not larger than 8.2%. The results show that the established optimization model has high precision and good generalization. It can be efficiently applied for optimizing CVI process parameters.
An optimization model of the process parameters during a chemical vapor infiltration (CVI) was established based on genetic algorithm and back propagation (GA-BP) neural network. The experimental data from the novel isothermal CVI process of carbon/carbon (C/C) composites were selected as the samples to evaluate the model. The effect of the main controllable factors, such as infiltration temperature, part pressure of precursor gas and resident time etc, on the density and uniformity of C/C composites were analyzed. Under the guidance of the model, the maximum errors between the desired densities and the tested densities of the experiment samples are not larger than 6.2% and those between their density differences were not larger than 8.2%. The results show that the established optimization model has high precision and good generalization. It can be efficiently applied for optimizing CVI process parameters.
2016, 33(11): 2674-2681.
doi: 10.13801/j.cnki.fhclxb.20160225.001
Abstract:
In order to obtain suitable phase change materials and phase transition temperature in the file of construction, lauric acid (LA)and palmitic acid (PA) were blended to prepare binary eutectic fatty acids (LA-PA) as energy storage material, bio-based SiO2 (b-SiO2)powder extracted from waste straw and straw ash was the carrier. Then LA-PA/b-SiO2 amorphous phase change energy storage materials were prepared by melt impregnation method. The structure and properties of LA-PA/b-SiO2 phase change composites were analyzed by FTIR, XRD, specific surface area analysis, SEM, DSC and TGA. The results show that there is not a simple physical interaction between the LA-PA and the b-SiO2. LA-PA is bound to the b-SiO2 porous network, thus the phase change materials will not leak when the solid phase is changed into a liquid phase. XRD analysis shows that the crystallinity of the LA-PA/b-SiO2 phase change composite decreases with the increase of b-SiO2 content. The DSC and TGA analysis show that the LA-PA/b-SiO2 phase change composites have good properties of phase transformation and thermal stability. The enthalpy of phase change is between 67.36-146.0 J/g.
In order to obtain suitable phase change materials and phase transition temperature in the file of construction, lauric acid (LA)and palmitic acid (PA) were blended to prepare binary eutectic fatty acids (LA-PA) as energy storage material, bio-based SiO2 (b-SiO2)powder extracted from waste straw and straw ash was the carrier. Then LA-PA/b-SiO2 amorphous phase change energy storage materials were prepared by melt impregnation method. The structure and properties of LA-PA/b-SiO2 phase change composites were analyzed by FTIR, XRD, specific surface area analysis, SEM, DSC and TGA. The results show that there is not a simple physical interaction between the LA-PA and the b-SiO2. LA-PA is bound to the b-SiO2 porous network, thus the phase change materials will not leak when the solid phase is changed into a liquid phase. XRD analysis shows that the crystallinity of the LA-PA/b-SiO2 phase change composite decreases with the increase of b-SiO2 content. The DSC and TGA analysis show that the LA-PA/b-SiO2 phase change composites have good properties of phase transformation and thermal stability. The enthalpy of phase change is between 67.36-146.0 J/g.
2016, 33(11): 2682-2687.
doi: 10.13801/j.cnki.fhclxb.20160220.001
Abstract:
SrTiO3 was supported on HZSM-5 molecular sieve by sol-gel method. XRD, FTIR, and N2 adsorption-desorption measurements were carried out to study the influences of supporting on photocatalytic degradation process of reactive brilliant red X-3B. The processes in photocatalytic degradation of reactive brilliant red X-3B were discussed after analyzing the data of FTIR spectra, ultraviolet-visible spectroscopy, and total organic carbon (TOC) data of the solutions during degradation. The results show that the photocatalysts are mainly composed of perovskite SrTiO3. Crystallite size of SrTiO3 has nearly no change after supporting. Pure SrTiO3 does not have apparent porous structure, so that specific surface area and pores of the supported samples are mainly provided by HZSM-5. Photocatalytic activity of the supported catalysts is obviously improved with the fastest decoloration and TOC removal rates on 30% SrTiO3/HZSM-5 for reactive brilliant red X-3B.
SrTiO3 was supported on HZSM-5 molecular sieve by sol-gel method. XRD, FTIR, and N2 adsorption-desorption measurements were carried out to study the influences of supporting on photocatalytic degradation process of reactive brilliant red X-3B. The processes in photocatalytic degradation of reactive brilliant red X-3B were discussed after analyzing the data of FTIR spectra, ultraviolet-visible spectroscopy, and total organic carbon (TOC) data of the solutions during degradation. The results show that the photocatalysts are mainly composed of perovskite SrTiO3. Crystallite size of SrTiO3 has nearly no change after supporting. Pure SrTiO3 does not have apparent porous structure, so that specific surface area and pores of the supported samples are mainly provided by HZSM-5. Photocatalytic activity of the supported catalysts is obviously improved with the fastest decoloration and TOC removal rates on 30% SrTiO3/HZSM-5 for reactive brilliant red X-3B.
2016, 33(11): 2688-2697.
doi: 10.13801/j.cnki.fhclxb.20160317.001
Abstract:
The delayed impregnation of dual-scale porous fiber preform during unsaturated flow process presents a challenge for the molding theory and simulation method which based on the assumption that the region nearing the flow front was completely filled and the flow was saturated during the filling process. Combined with sink function, the numerical simulation of unsaturated filling and infiltration for liquid composites molding (LCM) was realized by control volume/finite element (CV/FE) method, and the validity of the results was proven by the comparison of experimental results under the constant pressure, and the influences of injection pressure, flow rate and fluid viscosity on the unsaturated filling and infiltration characteristics of dual-scale porous fabric were also discussed. The results show that the numerical results are reliable and can be used to analyze different factors' impact on unsaturated flow characteristics of dual-scale porous fiber preform within permissible error; and the length of unsaturated region isn't constant during the whole filling process in fiber fabric which experiences four stages; pressure, flow rate and viscosity have different influence on unsaturated flow characteristic; the research results have guiding significance on appropriate manipulated injection conditions and fluid characteristic to realize the fully impregnation of dual-scale porous fiber preform.
The delayed impregnation of dual-scale porous fiber preform during unsaturated flow process presents a challenge for the molding theory and simulation method which based on the assumption that the region nearing the flow front was completely filled and the flow was saturated during the filling process. Combined with sink function, the numerical simulation of unsaturated filling and infiltration for liquid composites molding (LCM) was realized by control volume/finite element (CV/FE) method, and the validity of the results was proven by the comparison of experimental results under the constant pressure, and the influences of injection pressure, flow rate and fluid viscosity on the unsaturated filling and infiltration characteristics of dual-scale porous fabric were also discussed. The results show that the numerical results are reliable and can be used to analyze different factors' impact on unsaturated flow characteristics of dual-scale porous fiber preform within permissible error; and the length of unsaturated region isn't constant during the whole filling process in fiber fabric which experiences four stages; pressure, flow rate and viscosity have different influence on unsaturated flow characteristic; the research results have guiding significance on appropriate manipulated injection conditions and fluid characteristic to realize the fully impregnation of dual-scale porous fiber preform.
