2020 Vol. 37, No. 7
2020, 37(7): 1-5.
Abstract:
2020, 37(7): 1657-1666.
doi: 10.13801/j.cnki.fhclxb.20191120.003
Abstract:
The oxidized cellulose nanofibrils reinforcing regenerated cellulose (TOCNs/RC) all-cellulose composite films were prepared with 2,2,6,6-tetramethylpiperidinooxy (TEMPO) oxidized cellulose nanofibrils of pine powder as the reinforcments and RC of α-cellulose powder as the matrix by the sol-gel method. The properties of mechanical, optical, oxygen barrier, thermal stability of TOCNs/RC all-cellulose composite films with different mass ratios of TOCNs to RC were investigated. The structure, morphology of TOCNs/RC all-cellulose composite films and the rheology of cellulose solution were characterized by FTIR, SEM, TEM, XRD and rheometer. The results show that TOCNs have significant effects on the mechanical properties of TOCNs/RC all-cellulose composite films. The tensile strength and fracture energy of TOCNs/RC all-cellulose composite films reach at 134.3 MPa and 21.51 MJ·m−3 respectively with TOCNs content of 1.0% (mass ratio to cellulose matrix ) , which has the best comprehensive mechanical properties. The transmittance decreases and haze increases as the augment of the mass ratios of TOCNs, but TOCNs/RC all-cellulose composite films still maintain high transmittance (>85%) and low haze (<14%). The TOCNs/RC all-cellulose composite films also have excellent oxygen barrier property and the oxygen transmission coefficient reaches a minimum of 1.47×10−17cm3·cm/cm2·s·Pa at 1.6% TOCNs. The TOCNs/RC all-cellulose composite films have better tensile strength and oxygen barrier property than general plastic films and also have comparable transparency, which can be used as the strength or barrier layer for the flexible packaging composites and have profound application prospects in the field of green and high-performance packaging meterials.
The oxidized cellulose nanofibrils reinforcing regenerated cellulose (TOCNs/RC) all-cellulose composite films were prepared with 2,2,6,6-tetramethylpiperidinooxy (TEMPO) oxidized cellulose nanofibrils of pine powder as the reinforcments and RC of α-cellulose powder as the matrix by the sol-gel method. The properties of mechanical, optical, oxygen barrier, thermal stability of TOCNs/RC all-cellulose composite films with different mass ratios of TOCNs to RC were investigated. The structure, morphology of TOCNs/RC all-cellulose composite films and the rheology of cellulose solution were characterized by FTIR, SEM, TEM, XRD and rheometer. The results show that TOCNs have significant effects on the mechanical properties of TOCNs/RC all-cellulose composite films. The tensile strength and fracture energy of TOCNs/RC all-cellulose composite films reach at 134.3 MPa and 21.51 MJ·m−3 respectively with TOCNs content of 1.0% (mass ratio to cellulose matrix ) , which has the best comprehensive mechanical properties. The transmittance decreases and haze increases as the augment of the mass ratios of TOCNs, but TOCNs/RC all-cellulose composite films still maintain high transmittance (>85%) and low haze (<14%). The TOCNs/RC all-cellulose composite films also have excellent oxygen barrier property and the oxygen transmission coefficient reaches a minimum of 1.47×10−17cm3·cm/cm2·s·Pa at 1.6% TOCNs. The TOCNs/RC all-cellulose composite films have better tensile strength and oxygen barrier property than general plastic films and also have comparable transparency, which can be used as the strength or barrier layer for the flexible packaging composites and have profound application prospects in the field of green and high-performance packaging meterials.
2020, 37(7): 1667-1674.
doi: 10.13801/j.cnki.fhclxb.20191125.002
Abstract:
The epoxidized natural rubber(ENR) was an interfacial modifier for the preparation of graphene-carbon black/natural rubber-ENR(GR-CB/NR-ENR) composites. The effects of ENR dosage on the processing properties, mechanical properties and dynamic mechanical properties of GR-CB/NR-ENR composites were studied. The results show that the addition of ENR can improve the processing properties of GR-CB/NR-ENR composites and the dispersion of CB particles in NR matrix. Increasing the compatibility of GR with NR, the interfacial compatibility between the filler and the NR matrix is enhanced, the dynamic mechanical properties, physical properties and aging resistance are improved. When 6 wt% ENR is added, the GR-CB/NR-ENR composite has the highest tear strength and tensile strength, and the GR-CB/NR-ENR vulcanized rubber has the best aging resistance. As the ENR content increases, the compression fatigue temperature of the GR-CB/NR-ENR composite increases first and then decreases; As the strain increases, the storage modulus G' of the GR-CB/NR-ENR composite decreases continuously, and the loss factor tanδ shows a phenomenon of increasing first and then decreasing, while the dynamic modulus drops sharply with increasing strain.
The epoxidized natural rubber(ENR) was an interfacial modifier for the preparation of graphene-carbon black/natural rubber-ENR(GR-CB/NR-ENR) composites. The effects of ENR dosage on the processing properties, mechanical properties and dynamic mechanical properties of GR-CB/NR-ENR composites were studied. The results show that the addition of ENR can improve the processing properties of GR-CB/NR-ENR composites and the dispersion of CB particles in NR matrix. Increasing the compatibility of GR with NR, the interfacial compatibility between the filler and the NR matrix is enhanced, the dynamic mechanical properties, physical properties and aging resistance are improved. When 6 wt% ENR is added, the GR-CB/NR-ENR composite has the highest tear strength and tensile strength, and the GR-CB/NR-ENR vulcanized rubber has the best aging resistance. As the ENR content increases, the compression fatigue temperature of the GR-CB/NR-ENR composite increases first and then decreases; As the strain increases, the storage modulus G' of the GR-CB/NR-ENR composite decreases continuously, and the loss factor tanδ shows a phenomenon of increasing first and then decreasing, while the dynamic modulus drops sharply with increasing strain.
2020, 37(7): 1675-1683.
doi: 10.13801/j.cnki.fhclxb.20191113.004
Abstract:
The three different silane coupling agents (methyltriethoxysilane (MTES), dimethyldiethoxysilane (DMDES) and trimethylethoxysilane (TMES)) were used to modify the surface of multi-walled carbon nanotubes (MWCNTs) under the hydrous conditions. The chemical structures of MWCNTs before and after modification were characterized by FTIR, XPS, TG and SEM. The different mass fractions of MWCNTs, MWCNTs-MTES, MWCNTs-DMDES and MWCNTs-TMES were filled in silicone rubber (SR). The MWCNTs/SR composites were prepared by mechanical blending. SEM images show that the silane modification can reduce the interaction between MWCNTs and improve their dispersion in SR. The tensile tests show that the interaction between MWCNTs and SR is enhanced and the compatibility between them is improved. The elastic modulus of the MWCNTs/SR composites shows no obvious change when the contents of modified MWCNTs are within 2wt%. The dielectric constant of MWCNTs/SR composite reaches 5.02 (at 104 Hz) when filled with 2wt% modified MWCNTs-MTES, which is 57% higher than that of the pure SR, while the dielectric loss is still less than 0.01 (at 104 Hz).
The three different silane coupling agents (methyltriethoxysilane (MTES), dimethyldiethoxysilane (DMDES) and trimethylethoxysilane (TMES)) were used to modify the surface of multi-walled carbon nanotubes (MWCNTs) under the hydrous conditions. The chemical structures of MWCNTs before and after modification were characterized by FTIR, XPS, TG and SEM. The different mass fractions of MWCNTs, MWCNTs-MTES, MWCNTs-DMDES and MWCNTs-TMES were filled in silicone rubber (SR). The MWCNTs/SR composites were prepared by mechanical blending. SEM images show that the silane modification can reduce the interaction between MWCNTs and improve their dispersion in SR. The tensile tests show that the interaction between MWCNTs and SR is enhanced and the compatibility between them is improved. The elastic modulus of the MWCNTs/SR composites shows no obvious change when the contents of modified MWCNTs are within 2wt%. The dielectric constant of MWCNTs/SR composite reaches 5.02 (at 104 Hz) when filled with 2wt% modified MWCNTs-MTES, which is 57% higher than that of the pure SR, while the dielectric loss is still less than 0.01 (at 104 Hz).
2020, 37(7): 1684-1694.
doi: 10.13801/j.cnki.fhclxb.20191121.001
Abstract:
The β-SiC fibers with high degree of crystallinity were obtained by electrospinning combined with carbothermal reduction method using tetraethyl orthosilicate (TEOS) as silicon source and polyvinylpyrrolidone (PVP) as spinning agent. The specific surface area of β-SiC fibers is 92.6 m2/g, which show the electric double layer capacitance. The specific capacitance of β-SiC fibers is up to 155.7 F/g. A large number of NiCo2O4 nanowires with a diameter of about 15 nm were grown on the surface of SiC fibers via hydrothermal method in order to obtain NiCo2O4 nanowires/SiC composite fibers. The results show that nickel and cobalt elements are present in the form of Ni2+/Ni3+ and Co2+/Co3+, respectively. The specific capacitance is significantly improved by the synergistic effect of NiCo2O4 nanowires and SiC fiber, and the NiCo2O4 nanowires/SiC composite fibers show both electric double layer and pseudo capacitance. The specific capacitance of NiCo2O4 nanowires/SiC composite fibers is up to 300.3 F/g. When the power density is 58.1 W/kg, the energy density of NiCo2O4 nanowires/SiC composite fibers is 60.1 W·h/kg.
The β-SiC fibers with high degree of crystallinity were obtained by electrospinning combined with carbothermal reduction method using tetraethyl orthosilicate (TEOS) as silicon source and polyvinylpyrrolidone (PVP) as spinning agent. The specific surface area of β-SiC fibers is 92.6 m2/g, which show the electric double layer capacitance. The specific capacitance of β-SiC fibers is up to 155.7 F/g. A large number of NiCo2O4 nanowires with a diameter of about 15 nm were grown on the surface of SiC fibers via hydrothermal method in order to obtain NiCo2O4 nanowires/SiC composite fibers. The results show that nickel and cobalt elements are present in the form of Ni2+/Ni3+ and Co2+/Co3+, respectively. The specific capacitance is significantly improved by the synergistic effect of NiCo2O4 nanowires and SiC fiber, and the NiCo2O4 nanowires/SiC composite fibers show both electric double layer and pseudo capacitance. The specific capacitance of NiCo2O4 nanowires/SiC composite fibers is up to 300.3 F/g. When the power density is 58.1 W/kg, the energy density of NiCo2O4 nanowires/SiC composite fibers is 60.1 W·h/kg.
2020, 37(7): 1695-1702.
doi: 10.13801/j.cnki.fhclxb.20191209.001
Abstract:
The multilayer films consisting of polydimethyldiallyl ammonium chloride functionalized graphene (PDDA-GNs) and phosphomolybdate functionalized graphene (PMo12-GNs) ({PDDA-GNs/PMo12-GNs}) were fabricated on the substrate by layer-by-layer self-assembly technique. The {PDDA-GNs/PMo12-GNs} multilayer films were used as catalyst carrier for electrodeposition of Au nanoparticles (Au/{PDDA-GNs/PMo12-GNs}n). The Au/{PDDA-GNs/PMo12-GNs}n fabricated catalyst was characterized by XRD, XPS and SEM. The results indicate that Au nanoparticles are uniformly-dispersed on the {PDDA-GNs/PMo12-GNs}n multilayer films. Cyclic voltammetry (CV), chronoamperometry (It) and electrochemical impedance spectra (EIS) analyses show that the Au/{PDDA-GNs/PMo12-GNs}n has high electrocatalytic activity and stability regarding hydrazine oxidation. Compared with Au/glassy carbon electrode (GCE), the hydrazine oxidation current density of Au/{PDDA-GNs/PMo12-GNs}n increases from 0.46 mA/cm2 to 0.87 mA/cm2. And the steady current density of the Au/{PDDA-GNs/PMo12-GNs}n catalyst is 2.5 times as high as the Au/GCE catalyst.
The multilayer films consisting of polydimethyldiallyl ammonium chloride functionalized graphene (PDDA-GNs) and phosphomolybdate functionalized graphene (PMo12-GNs) ({PDDA-GNs/PMo12-GNs}) were fabricated on the substrate by layer-by-layer self-assembly technique. The {PDDA-GNs/PMo12-GNs} multilayer films were used as catalyst carrier for electrodeposition of Au nanoparticles (Au/{PDDA-GNs/PMo12-GNs}n). The Au/{PDDA-GNs/PMo12-GNs}n fabricated catalyst was characterized by XRD, XPS and SEM. The results indicate that Au nanoparticles are uniformly-dispersed on the {PDDA-GNs/PMo12-GNs}n multilayer films. Cyclic voltammetry (CV), chronoamperometry (It) and electrochemical impedance spectra (EIS) analyses show that the Au/{PDDA-GNs/PMo12-GNs}n has high electrocatalytic activity and stability regarding hydrazine oxidation. Compared with Au/glassy carbon electrode (GCE), the hydrazine oxidation current density of Au/{PDDA-GNs/PMo12-GNs}n increases from 0.46 mA/cm2 to 0.87 mA/cm2. And the steady current density of the Au/{PDDA-GNs/PMo12-GNs}n catalyst is 2.5 times as high as the Au/GCE catalyst.
2020, 37(7): 1703-1712.
doi: 10.13801/j.cnki.fhclxb.20191113.002
Abstract:
A series of nano SiO2 grafted with organosilane (HB-2200), nano SiO2 grafted with amino (HB-2205N), nano SiO2 grafted with double bond (HB-2205D) and nano SiO2 grafted with amino-double bond (HB-2205ND) groups were prepared through liquid phase in-situ surface modification method. The structure and properties of nano SiO2/solution polymerized styrene butadiene rubber-polybutadiene rubber (SSBR-BR) composites were characterized by TEM, SEM and rheometer. The results show that compared with the unmodified nano SiO2, the compatibility between surface functionalized nano SiO2 and rubber matrix is improved, Payne effect is reduced, the interaction between nano SiO2 is weakened, and the dispersion of nano SiO2 in SSBR-BR is improved. Compared with nano SiO2/SSBR-BR composite, the mixing torque of HB-2200/SSBR-BR composite is reduced by 35.7%, the mixing energy consumption is saved by 15%, the interfacial bond between the filler and the rubber is strengthened due to the increase in the content of bound rubber, and its tensile strength is increased by 60%. The dynamic mechanical and abrasion performance analyses show that the reactive double bond group grafted on the surface of SiO2 could improve the wet slip resistance of HB-2205D/SSBR-BR composite by 40% and reduce the rolling resistance by 43%. Nano SiO2 surface grafted with reactive double bond could reduce its rolling resistance and improve its resistance to wet slip, without sacrificing the wear resistance of HB-2205D/SSBR-BR composite. It provides the basic raw materials for the preparation of high-performance tires.
A series of nano SiO2 grafted with organosilane (HB-2200), nano SiO2 grafted with amino (HB-2205N), nano SiO2 grafted with double bond (HB-2205D) and nano SiO2 grafted with amino-double bond (HB-2205ND) groups were prepared through liquid phase in-situ surface modification method. The structure and properties of nano SiO2/solution polymerized styrene butadiene rubber-polybutadiene rubber (SSBR-BR) composites were characterized by TEM, SEM and rheometer. The results show that compared with the unmodified nano SiO2, the compatibility between surface functionalized nano SiO2 and rubber matrix is improved, Payne effect is reduced, the interaction between nano SiO2 is weakened, and the dispersion of nano SiO2 in SSBR-BR is improved. Compared with nano SiO2/SSBR-BR composite, the mixing torque of HB-2200/SSBR-BR composite is reduced by 35.7%, the mixing energy consumption is saved by 15%, the interfacial bond between the filler and the rubber is strengthened due to the increase in the content of bound rubber, and its tensile strength is increased by 60%. The dynamic mechanical and abrasion performance analyses show that the reactive double bond group grafted on the surface of SiO2 could improve the wet slip resistance of HB-2205D/SSBR-BR composite by 40% and reduce the rolling resistance by 43%. Nano SiO2 surface grafted with reactive double bond could reduce its rolling resistance and improve its resistance to wet slip, without sacrificing the wear resistance of HB-2205D/SSBR-BR composite. It provides the basic raw materials for the preparation of high-performance tires.
2020, 37(7): 1713-1720.
doi: 10.13801/j.cnki.fhclxb.20191030.002
Abstract:
The nanoscale spinel structure metal oxide possesses broad application prospect due to its unique crystal structure and band structure. The MnFe2O4/reduced graphene oxide (rGO) nanocomposites were synthesized by hydrothermal method, the crystal structure, morphology, element distribution, binding energy and optical properties were characterized by XRD, high-resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectrometer (EDX), FTIR, XPS, Raman spectroscopy (Raman), photoluminescence spectroscopy (PL) and UV-vis diffuse reflection spectroscopy (UV-vis DRS). The results show that the MnFe2O4/rGO nanocomposites prepared by this method have cubic spinel structure. The morphology is irregular ellipsoid with uniform particle size. MnFe2O4 nanoparticles loaded on the surface of rGO are partially coated with graphene, possessing small particle size and good dispersion. The MnFe2O4/rGO nanocomposites exhibit lower recombination efficiency of electron-hole pairs. The graphene has more defects and higher disorder degree. The oxygen-containing groups are partially reduced by polyvinyl pyrrolidone (PVP), and the quantity is greatly reduced. The band gap of MnFe2O4/rGO composite is narrower than that of pure MnFe2O4, resulting in red shift.
The nanoscale spinel structure metal oxide possesses broad application prospect due to its unique crystal structure and band structure. The MnFe2O4/reduced graphene oxide (rGO) nanocomposites were synthesized by hydrothermal method, the crystal structure, morphology, element distribution, binding energy and optical properties were characterized by XRD, high-resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectrometer (EDX), FTIR, XPS, Raman spectroscopy (Raman), photoluminescence spectroscopy (PL) and UV-vis diffuse reflection spectroscopy (UV-vis DRS). The results show that the MnFe2O4/rGO nanocomposites prepared by this method have cubic spinel structure. The morphology is irregular ellipsoid with uniform particle size. MnFe2O4 nanoparticles loaded on the surface of rGO are partially coated with graphene, possessing small particle size and good dispersion. The MnFe2O4/rGO nanocomposites exhibit lower recombination efficiency of electron-hole pairs. The graphene has more defects and higher disorder degree. The oxygen-containing groups are partially reduced by polyvinyl pyrrolidone (PVP), and the quantity is greatly reduced. The band gap of MnFe2O4/rGO composite is narrower than that of pure MnFe2O4, resulting in red shift.
2020, 37(7): 1721-1730.
doi: 10.13801/j.cnki.fhclxb.20191113.001
Abstract:
The CuO-ZnO/(ethylene glycol(EG)-water) nanofluid with CuO-ZnO mass fractions of 0–3 wt% were prepared by two-step method. First, the mixing mass ratio of nanoparticles CuO to ZnO was fixed at 50∶50, and the mass ratios of EG to deionized water varied from 20∶80 to 80∶20. Variations of thermal conductivity with temperature (25–60℃) and mixing mass ratios of base liquids were studied. Second, the radial basis function neural network (RBFNN) model was used to predict the thermal conductivity. In the model, the mass fraction, temperature and mixing mass ratios of base liquids were considered as independent variables while the thermal conductivity is the dependent variable. The predicted values were compared with the values predicted by back propagation neural network (BPNN) and multiple linear regression (MLR). The results show that the thermal conductivities of CuO-ZnO/(EG-water) nanofluid increase nonlinearly with the increase of temperature, while decrease with the increase of mixing mass ratios of base liquids. Compared with the thermal conductivity of the base fluid, it increases from 14.03% to 23.47% at the mass fraction of 3 wt% and the mixing mass ratio of base fluid of 20∶80. The thermal conductity of CuO-ZnO/(EG-water) changes nonlinear with random motion of nanoparticles and temperature. The results obtained by RBF model are more precise than that predited by BPNN model and MLR model. The model evaluated indexes of root mean square error (RMSE), mean relative percentage error (MRPE) and sum of squared error (SSE) are closer to 0 and duostatistical coefficient of multiple determination R2 is closer to 1 indicating that the RBFNN model can accurately predict the thermal conductivity. It can also be used to characterize the effect of various parameters on the thermal conductivity. The results offer an effective method to establish the data-driven model to accurately predict the thermal conductivity of CuO-ZnO/(EG-water) nanofluid.
The CuO-ZnO/(ethylene glycol(EG)-water) nanofluid with CuO-ZnO mass fractions of 0–3 wt% were prepared by two-step method. First, the mixing mass ratio of nanoparticles CuO to ZnO was fixed at 50∶50, and the mass ratios of EG to deionized water varied from 20∶80 to 80∶20. Variations of thermal conductivity with temperature (25–60℃) and mixing mass ratios of base liquids were studied. Second, the radial basis function neural network (RBFNN) model was used to predict the thermal conductivity. In the model, the mass fraction, temperature and mixing mass ratios of base liquids were considered as independent variables while the thermal conductivity is the dependent variable. The predicted values were compared with the values predicted by back propagation neural network (BPNN) and multiple linear regression (MLR). The results show that the thermal conductivities of CuO-ZnO/(EG-water) nanofluid increase nonlinearly with the increase of temperature, while decrease with the increase of mixing mass ratios of base liquids. Compared with the thermal conductivity of the base fluid, it increases from 14.03% to 23.47% at the mass fraction of 3 wt% and the mixing mass ratio of base fluid of 20∶80. The thermal conductity of CuO-ZnO/(EG-water) changes nonlinear with random motion of nanoparticles and temperature. The results obtained by RBF model are more precise than that predited by BPNN model and MLR model. The model evaluated indexes of root mean square error (RMSE), mean relative percentage error (MRPE) and sum of squared error (SSE) are closer to 0 and duostatistical coefficient of multiple determination R2 is closer to 1 indicating that the RBFNN model can accurately predict the thermal conductivity. It can also be used to characterize the effect of various parameters on the thermal conductivity. The results offer an effective method to establish the data-driven model to accurately predict the thermal conductivity of CuO-ZnO/(EG-water) nanofluid.
2020, 37(7): 1731-1742.
doi: 10.13801/j.cnki.fhclxb.20191010.001
Abstract:
In order to investigate the bonding and anchoring performance of high-strength stainless steel wire mesh in engineered cementitious composites (ECC), three parameters of transverse steel strand spacing, relative anchorage length and steel strand diameter were considered, and a total of 51 specimens in 17 groups were designed and carried out by the uniaxial pull-out test. The results show that the setting of transverse steel strand has obvious ductile failure characteristics. The transverse steel strand spacing has little effect on the bond strength, but the length of ductile strengthening section (ductility) increases with the decreasing of transverse steel strand spacing. The peak average bonding stress between the steel wire mesh and ECC is negatively correlated with the anchorage length and the steel strand diameter. The ductility increases with the increasing of the steel strand diameter, but decreases with the increasing of the anchorage length. The test results and analysis verify that the critical anchorage length calculation of the steel wire mesh in ECC can be calculated by using the critical anchorage length formula of a single steel strand.
In order to investigate the bonding and anchoring performance of high-strength stainless steel wire mesh in engineered cementitious composites (ECC), three parameters of transverse steel strand spacing, relative anchorage length and steel strand diameter were considered, and a total of 51 specimens in 17 groups were designed and carried out by the uniaxial pull-out test. The results show that the setting of transverse steel strand has obvious ductile failure characteristics. The transverse steel strand spacing has little effect on the bond strength, but the length of ductile strengthening section (ductility) increases with the decreasing of transverse steel strand spacing. The peak average bonding stress between the steel wire mesh and ECC is negatively correlated with the anchorage length and the steel strand diameter. The ductility increases with the increasing of the steel strand diameter, but decreases with the increasing of the anchorage length. The test results and analysis verify that the critical anchorage length calculation of the steel wire mesh in ECC can be calculated by using the critical anchorage length formula of a single steel strand.
2020, 37(7): 1743-1753.
doi: 10.13801/j.cnki.fhclxb.20190930.001
Abstract:
The slump, cube compressive strength and splitting tensile strength tests of 16 groups of basalt fiber-carbon fiber(BF-CF)/slag concrete and 1 group of C40 reference concrete were conducted by orthogonal experimental method. The effects of BF, CF and slag on the mechanical properties of BF-CF/slag concrete were investigated. The test results show that the cube compressive strength and splitting tensile strength of BF-CF/slag concrete are higher than the cube compressive strength and splitting tensile strength of C40 reference concrete, i.e., the maximum increase of cube compressive strength is 21.0%, and the maximum increase of splitting tensile strength is 35.3%. The addition of BF and CF can reduce the slump of concrete, and BF can reduce the slump more significantly. The maximum drop of BF to the slump is 67.1%. The mass fraction of slag replacing for sand is a significant factor affecting the cube compressive strength of BF-CF/slag concrete. With the increase of mass fraction of slag replacing for sand, the cube compressive strength first increases and then decreases, and the maximum increase of slag to the cube compressive strength is 7.6%. BF is a significant factor affecting the tensile strength of BF-CF/slag concrete, and the tensile strength increases with the increase of the volume fraction of BF. The maximum increase of BF to the tensile strength is 12.0%, and the increase of CF to the tensile strength is not obvious. The results of the orthogonal experiment were regressed, and the prediction models of the cube compressive strength and splitting tensile strength of the BF-CF/slag concrete were obtained, and the accuracy of model is high.
The slump, cube compressive strength and splitting tensile strength tests of 16 groups of basalt fiber-carbon fiber(BF-CF)/slag concrete and 1 group of C40 reference concrete were conducted by orthogonal experimental method. The effects of BF, CF and slag on the mechanical properties of BF-CF/slag concrete were investigated. The test results show that the cube compressive strength and splitting tensile strength of BF-CF/slag concrete are higher than the cube compressive strength and splitting tensile strength of C40 reference concrete, i.e., the maximum increase of cube compressive strength is 21.0%, and the maximum increase of splitting tensile strength is 35.3%. The addition of BF and CF can reduce the slump of concrete, and BF can reduce the slump more significantly. The maximum drop of BF to the slump is 67.1%. The mass fraction of slag replacing for sand is a significant factor affecting the cube compressive strength of BF-CF/slag concrete. With the increase of mass fraction of slag replacing for sand, the cube compressive strength first increases and then decreases, and the maximum increase of slag to the cube compressive strength is 7.6%. BF is a significant factor affecting the tensile strength of BF-CF/slag concrete, and the tensile strength increases with the increase of the volume fraction of BF. The maximum increase of BF to the tensile strength is 12.0%, and the increase of CF to the tensile strength is not obvious. The results of the orthogonal experiment were regressed, and the prediction models of the cube compressive strength and splitting tensile strength of the BF-CF/slag concrete were obtained, and the accuracy of model is high.
Tension constitutive relationship of hybrid fiber reinforced strain hardening cementitous composites
2020, 37(7): 1754-1762.
doi: 10.13801/j.cnki.fhclxb.20191114.001
Abstract:
Mechanical properties of steel fiber hybrid polyvinyl alcohol fiber reinforced strain hardening cementitious composites (SF-PVA/SHCC) have been one of the hot topics in recent years. However, there is still a lack of the theoretical model that can fully describe the constitutive relationship of SF-PVA/SHCC in tension. Based on the theory of fracture mechanics and micromechanics of concrete, a new uniaxial tension constitutive model for SF-PVA/SHCC was proposed by considering the softening stage of stress-strain curve and the effect of SF-PVA hybrid fibers on the tensile properties of SHCC. In order to verify the effectiveness of the proposed model, a series of single-axial tensile tests for SF-PVA/SHCC were performed. The influence of fiber type and fiber content on the tensile strength, tensile strain and tensile toughness of SHCC was analyzed. Through the comparison with the experimental results, it was found that the proposed model could well predict the tensile stress-strain relationship of SF-PVA/SHCC composite.
Mechanical properties of steel fiber hybrid polyvinyl alcohol fiber reinforced strain hardening cementitious composites (SF-PVA/SHCC) have been one of the hot topics in recent years. However, there is still a lack of the theoretical model that can fully describe the constitutive relationship of SF-PVA/SHCC in tension. Based on the theory of fracture mechanics and micromechanics of concrete, a new uniaxial tension constitutive model for SF-PVA/SHCC was proposed by considering the softening stage of stress-strain curve and the effect of SF-PVA hybrid fibers on the tensile properties of SHCC. In order to verify the effectiveness of the proposed model, a series of single-axial tensile tests for SF-PVA/SHCC were performed. The influence of fiber type and fiber content on the tensile strength, tensile strain and tensile toughness of SHCC was analyzed. Through the comparison with the experimental results, it was found that the proposed model could well predict the tensile stress-strain relationship of SF-PVA/SHCC composite.
2020, 37(7): 1763-1773.
doi: 10.13801/j.cnki.fhclxb.20191106.001
Abstract:
In order to investigate the effect of hybrid steel fibe (SF) and polypropylene fiber (PPF) on the impact resistance of the recycled aggregate concrete (RAC), the flexural impact resistances of plain RAC, SF/RAC, PPF/RAC and SF-PPF/RAC were studied by drop weight impact test. The effects of fiber content and the way of incorporation on the impact resistance of RAC were analyzed. The mathematical statistical model was used to fit the impact experimental results and predict the failure probability. The crack resistance enhancement mechanism of SF-PPF/RAC was further analyzed. The results indicate that both single fibers and hybrid fibers can improve the impact performance of RAC. The specimen with the hybrid volume fraction of 1.5vol% SF and volume fraction of 0.9vol% PPF is found to have the maximum increase in impact energy consumption and the best ductility and toughness in concrete matrix. The impact resistance numbers of SF-PPF/RAC are well subordinated to the two-parameter Weibull distribution. The SF-PPF exhibit significant hybrid effect on improving the impact resistance of RAC.
In order to investigate the effect of hybrid steel fibe (SF) and polypropylene fiber (PPF) on the impact resistance of the recycled aggregate concrete (RAC), the flexural impact resistances of plain RAC, SF/RAC, PPF/RAC and SF-PPF/RAC were studied by drop weight impact test. The effects of fiber content and the way of incorporation on the impact resistance of RAC were analyzed. The mathematical statistical model was used to fit the impact experimental results and predict the failure probability. The crack resistance enhancement mechanism of SF-PPF/RAC was further analyzed. The results indicate that both single fibers and hybrid fibers can improve the impact performance of RAC. The specimen with the hybrid volume fraction of 1.5vol% SF and volume fraction of 0.9vol% PPF is found to have the maximum increase in impact energy consumption and the best ductility and toughness in concrete matrix. The impact resistance numbers of SF-PPF/RAC are well subordinated to the two-parameter Weibull distribution. The SF-PPF exhibit significant hybrid effect on improving the impact resistance of RAC.
2020, 37(7): 1774-1784.
doi: 10.13801/j.cnki.fhclxb.20190917.002
Abstract:
The work aims to study the difference between recycled coarse aggregate concrete and normal concrete in failure mode and internal crack propagation. The recycled coarse aggregate concretes with different recycled coarse aggregate (RCA) replacement rates were used as the research object. Using the micro-focus industrial CT (Phoenix v | tome | x s240), 2D scanning images of recycled coarse aggregate concrete under 90% predicted failure load were obtained. With Photoshop CS6 image processing software, the failure crack in material was extracted. After that, based on the fractal geometry theory, the fractal dimension and multi-fractal spectrum were used to characterize the fractal propagation law of crack. Finally, the relationship between fractal dimension, multi-fractal spectrum characteristic parameters and RCA replacement rate and compressive strength was established. The results show that the meso-failure mode of recycled coarse aggregate concrete is different from that of normal concrete. The failure form of recycled coarse aggregate concrete depends on the interfacial transition zone (ITZ) between the coarse aggregate and the cement paste and the properties of RCA itself. When the crack develops to the natural coarse aggregate (NCA) or the RCA with higher strength, it will continue to develop around the surface of the aggregate, and it will penetrate through the aggregate when it is developed to the RCA with lower strength; The fractal dimension can quantitatively describe the overall propagation of meso-crack inside the concrete materials, that is, the richer the crack, the larger the fractal dimension; Multi-fractal spectrum can reflect the characteristics of meso-crack at different levels from local to global; The fractal dimension and multi-fractal spectrum characteristic parameters of crack have a linear negative correlation with the RCA replacement rate, and have a linear positive correlation with the compressive strength; This study can lay a theoretical and experimental basis for the wide application of recycled concrete in large-scale structural engineering.
The work aims to study the difference between recycled coarse aggregate concrete and normal concrete in failure mode and internal crack propagation. The recycled coarse aggregate concretes with different recycled coarse aggregate (RCA) replacement rates were used as the research object. Using the micro-focus industrial CT (Phoenix v | tome | x s240), 2D scanning images of recycled coarse aggregate concrete under 90% predicted failure load were obtained. With Photoshop CS6 image processing software, the failure crack in material was extracted. After that, based on the fractal geometry theory, the fractal dimension and multi-fractal spectrum were used to characterize the fractal propagation law of crack. Finally, the relationship between fractal dimension, multi-fractal spectrum characteristic parameters and RCA replacement rate and compressive strength was established. The results show that the meso-failure mode of recycled coarse aggregate concrete is different from that of normal concrete. The failure form of recycled coarse aggregate concrete depends on the interfacial transition zone (ITZ) between the coarse aggregate and the cement paste and the properties of RCA itself. When the crack develops to the natural coarse aggregate (NCA) or the RCA with higher strength, it will continue to develop around the surface of the aggregate, and it will penetrate through the aggregate when it is developed to the RCA with lower strength; The fractal dimension can quantitatively describe the overall propagation of meso-crack inside the concrete materials, that is, the richer the crack, the larger the fractal dimension; Multi-fractal spectrum can reflect the characteristics of meso-crack at different levels from local to global; The fractal dimension and multi-fractal spectrum characteristic parameters of crack have a linear negative correlation with the RCA replacement rate, and have a linear positive correlation with the compressive strength; This study can lay a theoretical and experimental basis for the wide application of recycled concrete in large-scale structural engineering.
2020, 37(7): 1505-1512.
doi: 10.13801/j.cnki.fhclxb.20191211.001
Abstract:
The 4,4′-diaminodiphenylmethane bismaleimide (BDM)/4,4′-o-diallylbisphenol A (DABPA) resin system was modified by synthesized thermoplastic polyimide (PI) via pre-in situ polymerization, used to prepare modified bismaleimide resin with high heat resistance (BDPI). The micromorphology and heat resistance of BDPI resin were investigated. The T800H carbon fiber/BDPI prepreg was fabricated through pre-in situ self-strengthening technology. The surface morphology of T800H/BDPI prepreg was studied by SEM. The mechanical properties and fracture morphology of T800H/BDPI composites at room temperature and high temperature were evaluated. The results show that the BDPI resin is suitable for prepreg processing technology, and the BDM microparticles with 30–70 μm size are well covered on the surface of T800H/BDPI prepreg. The glass transition temperature (Tg) and 5% mass loss temperature (Td5) of the cured BDPI resin reach 367℃ and 452℃, respectively. The 0° tensile strength, 0° tensile modulus and interlaminar shear strength of T800H/BDPI unidirectional composites are 2 440 MPa, 148 GPa and 107 MPa, respectively, the retention of which are approximately 66.4%, 87.2% and 44.1% at 280℃, respectively.
The 4,4′-diaminodiphenylmethane bismaleimide (BDM)/4,4′-o-diallylbisphenol A (DABPA) resin system was modified by synthesized thermoplastic polyimide (PI) via pre-in situ polymerization, used to prepare modified bismaleimide resin with high heat resistance (BDPI). The micromorphology and heat resistance of BDPI resin were investigated. The T800H carbon fiber/BDPI prepreg was fabricated through pre-in situ self-strengthening technology. The surface morphology of T800H/BDPI prepreg was studied by SEM. The mechanical properties and fracture morphology of T800H/BDPI composites at room temperature and high temperature were evaluated. The results show that the BDPI resin is suitable for prepreg processing technology, and the BDM microparticles with 30–70 μm size are well covered on the surface of T800H/BDPI prepreg. The glass transition temperature (Tg) and 5% mass loss temperature (Td5) of the cured BDPI resin reach 367℃ and 452℃, respectively. The 0° tensile strength, 0° tensile modulus and interlaminar shear strength of T800H/BDPI unidirectional composites are 2 440 MPa, 148 GPa and 107 MPa, respectively, the retention of which are approximately 66.4%, 87.2% and 44.1% at 280℃, respectively.
2020, 37(7): 1513-1521.
doi: 10.13801/j.cnki.fhclxb.20191031.001
Abstract:
Polyacrylonitrile (PAN) nanofibers were fabricated by electrospinning and collected on sheath-core polyethylene-polypropylene (PE-PP) bicomponent microfiber web to prepare PAN/PE-PP monolayer composite fiber webs. Then several monolayer composite webs were stacked and strengthened by thermal bonding to prepare PAN/PE-PP multilayer composite filters. The effects of the number of layers of PAN/PE-PP composite webs and electrospinning time on the pore size and the filtration performance were studied. The results show that the pore size parameters of multilayer composite materials are similar with that of monolayer composite material, but the pore structures of the two materials are different. At the same total areal density and total electrospinning time, when the number of layers of PAN/PE-PP composite webs is more than 10, the filtration efficiency and quality factor QF of PAN/PE-PP multilayer composite filters are significantly larger than that of PAN/PE-PP monolayer composite filter, and the resistance is increased slightly. Compared with PAN/PE-PP monolayer composite filter, the filtration efficiency of 20 layers of PAN/PE-PP composite filter to ≥0.3 μm particles is increased by 33%, the resistance is increased by 5 Pa, and the QF is increased by 30%. At the same total areal density and number of layers, when the electrospinning time is prolonged to more than 210 min, the filtration efficiency of 20 layers of PAN/PE-PP composite filter can be increased to more than 90%, but the resistance also increases sharply, hence the filtration performance of 20 layers of PAN/PE-PP composite filter with electrospinning time of 210 min is the best. Therefore, compared with PAN/PE-PP monolayer composite filter with the same areal density, the filtration performance of PAN/PE-PP multilayer composite filters is obviously improved. The micro-nano fiber multilayer composite method is an effective method to prepare high efficiency and low resistance composite air filters.
Polyacrylonitrile (PAN) nanofibers were fabricated by electrospinning and collected on sheath-core polyethylene-polypropylene (PE-PP) bicomponent microfiber web to prepare PAN/PE-PP monolayer composite fiber webs. Then several monolayer composite webs were stacked and strengthened by thermal bonding to prepare PAN/PE-PP multilayer composite filters. The effects of the number of layers of PAN/PE-PP composite webs and electrospinning time on the pore size and the filtration performance were studied. The results show that the pore size parameters of multilayer composite materials are similar with that of monolayer composite material, but the pore structures of the two materials are different. At the same total areal density and total electrospinning time, when the number of layers of PAN/PE-PP composite webs is more than 10, the filtration efficiency and quality factor QF of PAN/PE-PP multilayer composite filters are significantly larger than that of PAN/PE-PP monolayer composite filter, and the resistance is increased slightly. Compared with PAN/PE-PP monolayer composite filter, the filtration efficiency of 20 layers of PAN/PE-PP composite filter to ≥0.3 μm particles is increased by 33%, the resistance is increased by 5 Pa, and the QF is increased by 30%. At the same total areal density and number of layers, when the electrospinning time is prolonged to more than 210 min, the filtration efficiency of 20 layers of PAN/PE-PP composite filter can be increased to more than 90%, but the resistance also increases sharply, hence the filtration performance of 20 layers of PAN/PE-PP composite filter with electrospinning time of 210 min is the best. Therefore, compared with PAN/PE-PP monolayer composite filter with the same areal density, the filtration performance of PAN/PE-PP multilayer composite filters is obviously improved. The micro-nano fiber multilayer composite method is an effective method to prepare high efficiency and low resistance composite air filters.
2020, 37(7): 1522-1530.
doi: 10.13801/j.cnki.fhclxb.20191024.001
Abstract:
The effects of nano Serpentine, nano La2O3 and environmental factors on the tribological properties of nano Serpentine-nano La2O3/polytetrafluoroethylene(PTFE) composites were investigated by orthogonal test. The self-made sand-dust environment simulation device was used to improve the existing MMU-5G friction and wear tester, and the tribological experiment was carried out using the test machine. The wear surface and transfer film morphology of the nano Serpentine-nano La2O3/PTFE composites were observed by SEM and the wear mechanism was analyzed. The results show that the friction coefficient of nano Serpentine-nano La2O3/PTFE composites is greatly influenced by the environmental factors and the friction coefficient of dry friction is lower than that in sand-dust environment. The nano Serpentine content has the greatest influence on the wear rate of nano Serpentine-nano La2O3/PTFE composites. When the nano Serpentine mass fraction is 9wt%, the wear rate of nano Serpentine-nano La2O3/PTFE composites is the lowest. The wear mechanism of dry friction is mainly adhesive wear, and the wear mechanism in sand-dust environment is mainly abrasive wear.
The effects of nano Serpentine, nano La2O3 and environmental factors on the tribological properties of nano Serpentine-nano La2O3/polytetrafluoroethylene(PTFE) composites were investigated by orthogonal test. The self-made sand-dust environment simulation device was used to improve the existing MMU-5G friction and wear tester, and the tribological experiment was carried out using the test machine. The wear surface and transfer film morphology of the nano Serpentine-nano La2O3/PTFE composites were observed by SEM and the wear mechanism was analyzed. The results show that the friction coefficient of nano Serpentine-nano La2O3/PTFE composites is greatly influenced by the environmental factors and the friction coefficient of dry friction is lower than that in sand-dust environment. The nano Serpentine content has the greatest influence on the wear rate of nano Serpentine-nano La2O3/PTFE composites. When the nano Serpentine mass fraction is 9wt%, the wear rate of nano Serpentine-nano La2O3/PTFE composites is the lowest. The wear mechanism of dry friction is mainly adhesive wear, and the wear mechanism in sand-dust environment is mainly abrasive wear.
2020, 37(7): 1531-1538.
doi: 10.13801/j.cnki.fhclxb.20191017.001
Abstract:
In order to investigate the aging problem of glass fiber reinforced polymer(GFRP) composites as the lining of thermal power chimney, the glass fiber/epoxy(GF/EP) composite was taken as the research object. The effects of temperature, coupling agent content and heat flux aging time on the mass loss rate, bending strength and shear properties of GF/EP composite were studied by orthogonal test. The porosity of the GF/EP composite was measured and calculated by means of metallographic microscopic image processing and in-situ real-time detection system. The results show that different factors have different effects on the properties of GF/EP composites. The increase of coupling agent content can improve the mass loss rate of GF/EP composite. Temperature has a great influence on the bending strength. The post-curing behavior of the GF/EP composite itself will affect the change trend of bending performance, which still decreases by 11.8% as the temperature increasing. The interlaminar shear strength of the GF/EP composite is closely related to the thermal aging time, and the mean interlaminar shear strength is 10.2% higher at 16 h than that at 8 h.
In order to investigate the aging problem of glass fiber reinforced polymer(GFRP) composites as the lining of thermal power chimney, the glass fiber/epoxy(GF/EP) composite was taken as the research object. The effects of temperature, coupling agent content and heat flux aging time on the mass loss rate, bending strength and shear properties of GF/EP composite were studied by orthogonal test. The porosity of the GF/EP composite was measured and calculated by means of metallographic microscopic image processing and in-situ real-time detection system. The results show that different factors have different effects on the properties of GF/EP composites. The increase of coupling agent content can improve the mass loss rate of GF/EP composite. Temperature has a great influence on the bending strength. The post-curing behavior of the GF/EP composite itself will affect the change trend of bending performance, which still decreases by 11.8% as the temperature increasing. The interlaminar shear strength of the GF/EP composite is closely related to the thermal aging time, and the mean interlaminar shear strength is 10.2% higher at 16 h than that at 8 h.
2020, 37(7): 1539-1546.
doi: 10.13801/j.cnki.fhclxb.20191113.003
Abstract:
In order to investigate the effect of strong ultraviolet and dry heat environment on the aging resistance of wood-plastic composites in Xinjiang, the anti-aging agent(UV-531, 1010 and 168) was used to prepare wheat straw/polyvinyl chloride(PVC) composites by extrusion molding. The wheat straw/PVC composites were subject to outdoor exposure aging in Xinjiang for 90 days. The changes of surface functional groups, color changes, surface morphology and mechanical properties of the wheat straw/PVC composites before and after aging were tested and analyzed, and the carbonyl index, lignin index and surface roughness were calculated. The results show that three anti-aging agents can improve the aging resistance of wheat straw/PVC composites. After aging for 90 days, the functional groups on wheat straw/PVC composites surface change significantly indicating the decomposition of the wheat straw/PVC composites surface. Compared with the control group, the carbonyl index of the wheat straw/PVC composites added with UV-531 increases by 19.27%, the lignin index decreases by 4.44%, the color difference ΔE decreases by 11.12%, and the surface roughness Sa decreases by 33.38%, the flexural strength and tensile strength are increased by 5.87% and 6.44%, the surface is smoother, and the wheat straws are less exposed. The results will provide experimental data and theoretical reference for improving the anti-aging effect of wood-plastic composites, which is beneficial to prolong the service life of wood-plastic composites under dry heat conditions in Xinjiang.
In order to investigate the effect of strong ultraviolet and dry heat environment on the aging resistance of wood-plastic composites in Xinjiang, the anti-aging agent(UV-531, 1010 and 168) was used to prepare wheat straw/polyvinyl chloride(PVC) composites by extrusion molding. The wheat straw/PVC composites were subject to outdoor exposure aging in Xinjiang for 90 days. The changes of surface functional groups, color changes, surface morphology and mechanical properties of the wheat straw/PVC composites before and after aging were tested and analyzed, and the carbonyl index, lignin index and surface roughness were calculated. The results show that three anti-aging agents can improve the aging resistance of wheat straw/PVC composites. After aging for 90 days, the functional groups on wheat straw/PVC composites surface change significantly indicating the decomposition of the wheat straw/PVC composites surface. Compared with the control group, the carbonyl index of the wheat straw/PVC composites added with UV-531 increases by 19.27%, the lignin index decreases by 4.44%, the color difference ΔE decreases by 11.12%, and the surface roughness Sa decreases by 33.38%, the flexural strength and tensile strength are increased by 5.87% and 6.44%, the surface is smoother, and the wheat straws are less exposed. The results will provide experimental data and theoretical reference for improving the anti-aging effect of wood-plastic composites, which is beneficial to prolong the service life of wood-plastic composites under dry heat conditions in Xinjiang.
2020, 37(7): 1547-1554.
doi: 10.13801/j.cnki.fhclxb.20191113.005
Abstract:
Hybrid materials composed of Sn nano particles deposited on BN surface (BN-Sn NPs) were constructed as thermal conductive and electrical insulating fillers for epoxy(EP) by liquid-phase chemical reduction method. The diameter and melting point of Sn nano particles on BN-Sn NPs surface are 10–30 nm and 166.5–195.3℃, respectively. Both the Zeta potential of BN-Sn NPs powder and thermal conductivity of BN-Sn NPs pressed sheet increase, while the contact angle of EP droped on BN-Sn NPs pressed sheet decreases after BN surface deposited with nano Sn. During the curing process of BN-Sn NPs/EP composites, the nano Sn particles on BN-Sn NPs surface melt and sinter, simultaneously bridge the individual fillers, which results in the lower thermal contact resistance between the fillers, and the improved interfacial behavior. The feature of enhanced thermal conductivity reflects in BN-Sn NPs/EP composites. When the filler volume fraction is 30vol%, the thermal conductivity of BN-Sn NPs/EP composites reaches 1.61 W(m·K)−1, nearly 50% higher than that of the pristine BN/EP composites (1.08 W(m·K)−1). The results of Monte Carlo simulation demonstrate that the thermal contact resistance (Rc) of BN and BN-Sn NPs in the EP matrix are 6.1×106 K·W−1 and 3.7×106 K·W−1, respectively. The BN-Sn NPs/EP composites exhibit higher dielectric loss and lower dielectric strength and volume resistivity than that of the pristine BN/EP composites, while still have good electrical insulating properties.
Hybrid materials composed of Sn nano particles deposited on BN surface (BN-Sn NPs) were constructed as thermal conductive and electrical insulating fillers for epoxy(EP) by liquid-phase chemical reduction method. The diameter and melting point of Sn nano particles on BN-Sn NPs surface are 10–30 nm and 166.5–195.3℃, respectively. Both the Zeta potential of BN-Sn NPs powder and thermal conductivity of BN-Sn NPs pressed sheet increase, while the contact angle of EP droped on BN-Sn NPs pressed sheet decreases after BN surface deposited with nano Sn. During the curing process of BN-Sn NPs/EP composites, the nano Sn particles on BN-Sn NPs surface melt and sinter, simultaneously bridge the individual fillers, which results in the lower thermal contact resistance between the fillers, and the improved interfacial behavior. The feature of enhanced thermal conductivity reflects in BN-Sn NPs/EP composites. When the filler volume fraction is 30vol%, the thermal conductivity of BN-Sn NPs/EP composites reaches 1.61 W(m·K)−1, nearly 50% higher than that of the pristine BN/EP composites (1.08 W(m·K)−1). The results of Monte Carlo simulation demonstrate that the thermal contact resistance (Rc) of BN and BN-Sn NPs in the EP matrix are 6.1×106 K·W−1 and 3.7×106 K·W−1, respectively. The BN-Sn NPs/EP composites exhibit higher dielectric loss and lower dielectric strength and volume resistivity than that of the pristine BN/EP composites, while still have good electrical insulating properties.
2020, 37(7): 1555-1561.
doi: 10.13801/j.cnki.fhclxb.20191128.001
Abstract:
The TiO2@Ag/polyvinylidene fluoride(PVDF) composite membranes with different Ag contents were prepared by photochemical reduction deposition and solution scraping methods. The physical properties and photocatalytic properties of the TiO2@Ag/PVDF composite membranes were analyzed by electronic universal material testing machine, UV-visible near-infrared spectrophotometer, XRD and so on. The results show that compared with pure TiO2/PVDF composite membranes, the tensile strength of TiO2@Ag/PVDF composite membranes is obviously increased but the breaking elongation is decreased, and TiO2@Ag/PVDF composite membranes can promote the response spectral range of TiO2 to visible region. Furthermore, the photocatalytic degradation abilities of the TiO2@Ag/PVDF composite membranes increase at first and then decrease with the increase of loaded Ag. Moreover, the TiO2@Ag/PVDF composite membranes have excellent reusability and self-cleaning effect in visible right. Above all, the TiO2@Ag/PVDF composite membranes prepared by the experiment can satisfy the needs of practical applications. The TiO2@Ag/PVDF composite membranes loaded with Ag have a significant potential foreground in photocatalytic degradation field.
The TiO2@Ag/polyvinylidene fluoride(PVDF) composite membranes with different Ag contents were prepared by photochemical reduction deposition and solution scraping methods. The physical properties and photocatalytic properties of the TiO2@Ag/PVDF composite membranes were analyzed by electronic universal material testing machine, UV-visible near-infrared spectrophotometer, XRD and so on. The results show that compared with pure TiO2/PVDF composite membranes, the tensile strength of TiO2@Ag/PVDF composite membranes is obviously increased but the breaking elongation is decreased, and TiO2@Ag/PVDF composite membranes can promote the response spectral range of TiO2 to visible region. Furthermore, the photocatalytic degradation abilities of the TiO2@Ag/PVDF composite membranes increase at first and then decrease with the increase of loaded Ag. Moreover, the TiO2@Ag/PVDF composite membranes have excellent reusability and self-cleaning effect in visible right. Above all, the TiO2@Ag/PVDF composite membranes prepared by the experiment can satisfy the needs of practical applications. The TiO2@Ag/PVDF composite membranes loaded with Ag have a significant potential foreground in photocatalytic degradation field.
2020, 37(7): 1562-1570.
doi: 10.13801/j.cnki.fhclxb.20191120.002
Abstract:
Micro-nano SiC/epoxy (EP) composites with different filler proportions were prepared with micro and nano SiC as the fillers. The glass transition temperature, room-temperature dielectric spectrum and direct current (DC) conduction of the micro-nano SiC/EP composites were measured. The effects of the interface between filler and matrix on the glass transition temperature, dielectric spectrum and DC conduction characteristics were analyzed. The results show that when the micro and nano SiC fillers are used together, the glass transition temperature of micro-nano SiC/EP composites decreases first and then increases with the increasing nano SiC filler content. At the same frequency, the micro-nano SiC/EP composites have lower relative permittivity and low-frequency loss peak. Compared with EP, the micro-nano SiC/EP composites present significant nonlinear conduction characteristics. In contrast with micro SiC/EP composite, the micro-nano SiC/EP composites have higher nonlinear exponent and switching electric field. The nonlinear conduction characteristics of micro-nano SiC/EP composites are closely related to the interfacial region between SiC particles and EP matrix.
Micro-nano SiC/epoxy (EP) composites with different filler proportions were prepared with micro and nano SiC as the fillers. The glass transition temperature, room-temperature dielectric spectrum and direct current (DC) conduction of the micro-nano SiC/EP composites were measured. The effects of the interface between filler and matrix on the glass transition temperature, dielectric spectrum and DC conduction characteristics were analyzed. The results show that when the micro and nano SiC fillers are used together, the glass transition temperature of micro-nano SiC/EP composites decreases first and then increases with the increasing nano SiC filler content. At the same frequency, the micro-nano SiC/EP composites have lower relative permittivity and low-frequency loss peak. Compared with EP, the micro-nano SiC/EP composites present significant nonlinear conduction characteristics. In contrast with micro SiC/EP composite, the micro-nano SiC/EP composites have higher nonlinear exponent and switching electric field. The nonlinear conduction characteristics of micro-nano SiC/EP composites are closely related to the interfacial region between SiC particles and EP matrix.
2020, 37(7): 1571-1580.
doi: 10.13801/j.cnki.fhclxb.20191120.001
Abstract:
The graphene oxide(GO) was deposited on the surface of continuous carbon fiber(CF) by ultrasonic assisted electrophoresis deposition in isopropyl alcohol for the modification of the surface of CF. Then the adhesion between GO and CF was enhanced by high temperature treatment under 200℃, which would increase the interfacial bonding strength of CF/epoxy(EP) composites. The surface morphology and microstructure of the CF before and after modification were characterized by SEM and AFM, and the changes of the surface functional groups of CF before and after modification were tested by XPS. The results show that the tensile strength of the modified CF is increased by 34.58% after deposition of GO and treatment under 200℃. The reason for the improvement is that some partially reduced GO sheets fill or bridge the defects on the surface of CF. At the same time, the adhesion between RGO and CF is enhanced by the linkage of chemical bond after high temperature treatment. And the interfacial shear strength (IFSS) of RGO-CF/EP composites is increased by 69.9%.
The graphene oxide(GO) was deposited on the surface of continuous carbon fiber(CF) by ultrasonic assisted electrophoresis deposition in isopropyl alcohol for the modification of the surface of CF. Then the adhesion between GO and CF was enhanced by high temperature treatment under 200℃, which would increase the interfacial bonding strength of CF/epoxy(EP) composites. The surface morphology and microstructure of the CF before and after modification were characterized by SEM and AFM, and the changes of the surface functional groups of CF before and after modification were tested by XPS. The results show that the tensile strength of the modified CF is increased by 34.58% after deposition of GO and treatment under 200℃. The reason for the improvement is that some partially reduced GO sheets fill or bridge the defects on the surface of CF. At the same time, the adhesion between RGO and CF is enhanced by the linkage of chemical bond after high temperature treatment. And the interfacial shear strength (IFSS) of RGO-CF/EP composites is increased by 69.9%.
2020, 37(7): 1581-1589.
doi: 10.13801/j.cnki.fhclxb.20191226.002
Abstract:
The kenaf fiber(KF) was modified with the alkali peroxide in the aqueous solution. The refined KF-cotton fiber(KF-CF) blended fabrics with different blending mass ratios and KF-CF/epoxy(EP) composites were prepared. The single fiber tester, microscope, FTIR, TG and SEM were used to study the effect of fine treatment on the properties of KF. The best blending mass ratio was obtained by analyzing the mechanical properties of KF-CF/EP composites. The hygroscopicity of KF-CF/EP composites under hydrothermal and chemical conditions was investigated at the optimum blending ratio. The results show that the diameter of KF decreases by 30.66%, the Young’s modulus increases by 31.24%, the softness increases by 13.20%, and the thermal stability improves after refinement treatment. The KF-CF/EP composite with mass ratio of 40∶60 has the best mechanical properties with tensile strength of 101.90 MPa and flexural strength of 189.64 MPa. In the humid and hot environment, the longer the time and the higher the temperature, the higher the water absorption rate of the KF-CF/EP composite, and the alkaline environment leads the water absorption rate of the KF-CF/EP composite to increase.
The kenaf fiber(KF) was modified with the alkali peroxide in the aqueous solution. The refined KF-cotton fiber(KF-CF) blended fabrics with different blending mass ratios and KF-CF/epoxy(EP) composites were prepared. The single fiber tester, microscope, FTIR, TG and SEM were used to study the effect of fine treatment on the properties of KF. The best blending mass ratio was obtained by analyzing the mechanical properties of KF-CF/EP composites. The hygroscopicity of KF-CF/EP composites under hydrothermal and chemical conditions was investigated at the optimum blending ratio. The results show that the diameter of KF decreases by 30.66%, the Young’s modulus increases by 31.24%, the softness increases by 13.20%, and the thermal stability improves after refinement treatment. The KF-CF/EP composite with mass ratio of 40∶60 has the best mechanical properties with tensile strength of 101.90 MPa and flexural strength of 189.64 MPa. In the humid and hot environment, the longer the time and the higher the temperature, the higher the water absorption rate of the KF-CF/EP composite, and the alkaline environment leads the water absorption rate of the KF-CF/EP composite to increase.
2020, 37(7): 1590-1600.
doi: 10.13801/j.cnki.fhclxb.20191011.001
Abstract:
Experiments for shear stability analysis were conducted on composite stiffened panels SS-1 and SS-2 with different T-stringer layups. The L laminate layers of SS-1 and SS-2 were 11 and 14 layers respectively, the web laminate layers were 22 and 28 layers respectively, and the edge strip laminate layers were 15 and 18 layers respectively. Considering the differences of dimension and ply number of stringers, a proposed engineering method was used to investigate the shear buckling strain of skins, and finite element analysis (FEA) with arc-length method was also carried out to predict the shear buckling load, post-buckling carrying capabilities, and buckling modes. Experimental results show that the skins between stringers are in pure shear with uniform shear strains before buckling, and debonding failure of skin and stringers occur during post-buckling stage, and SS-2 with more stringer plys poses higher buckling resistance with larger buckling load and strain. The errors of buckling shear strain for SS-1 and SS-2 by the proposed engineering method are –14.9% and –9.2%, respectively. The errors of buckling load and buckling strain by arc-length method for SS-1 are 1.9% and 2.7%, respectively, and the buckling modes are also consistent with the experiment results. The FEA results by arc-length method also reveal that material failure will occur with less stringer plys due to overall buckling of panels, and the debonding of skin and stringers are more readily realized with more stringer plys.
Experiments for shear stability analysis were conducted on composite stiffened panels SS-1 and SS-2 with different T-stringer layups. The L laminate layers of SS-1 and SS-2 were 11 and 14 layers respectively, the web laminate layers were 22 and 28 layers respectively, and the edge strip laminate layers were 15 and 18 layers respectively. Considering the differences of dimension and ply number of stringers, a proposed engineering method was used to investigate the shear buckling strain of skins, and finite element analysis (FEA) with arc-length method was also carried out to predict the shear buckling load, post-buckling carrying capabilities, and buckling modes. Experimental results show that the skins between stringers are in pure shear with uniform shear strains before buckling, and debonding failure of skin and stringers occur during post-buckling stage, and SS-2 with more stringer plys poses higher buckling resistance with larger buckling load and strain. The errors of buckling shear strain for SS-1 and SS-2 by the proposed engineering method are –14.9% and –9.2%, respectively. The errors of buckling load and buckling strain by arc-length method for SS-1 are 1.9% and 2.7%, respectively, and the buckling modes are also consistent with the experiment results. The FEA results by arc-length method also reveal that material failure will occur with less stringer plys due to overall buckling of panels, and the debonding of skin and stringers are more readily realized with more stringer plys.
2020, 37(7): 1601-1610.
doi: 10.13801/j.cnki.fhclxb.20190905.001
Abstract:
In order to study the vibration characteristic of composite honeycomb structure under hygrothermal condition, the natural frequencies of honeycomb structure composed by carbon fiber/bismaleimide composite laminate and Nomex core were numerically analyzed under different temperatures and humidities. Based on the piecewise shear deformation theory, considering the honeycomb thin plate and thick plate respectively, the eigenvibration equation of composite honeycomb structure was solved by finite element method using the equivalence of temperature and humidity. A detailed model of composite honeycomb structure with four-edge clamped support was established by using finite element software ABAQUS. The effects of temperature, humidity, and combined temperature and humidity on the vibration characteristic of composite honeycomb thin plate and thick plate were discussed respectively. The numerical results show that compared with the increase of temperature, the natural frequencies of honeycomb structure are more sensitive to the increase of moisture concentration. Under the same humid and thermal environment, the natural frequency of the thick plate structure is larger than that of the thin plate, and the higher order of natural frequency, the greater the increase of natural frequency. The coupling effect of temperature and humidity has a greater effect on the natural frequency of composite honeycomb structure than the superposition of temperature and humidity when they act alone, and this effect is more obvious for the composite honeycomb thin plate.
In order to study the vibration characteristic of composite honeycomb structure under hygrothermal condition, the natural frequencies of honeycomb structure composed by carbon fiber/bismaleimide composite laminate and Nomex core were numerically analyzed under different temperatures and humidities. Based on the piecewise shear deformation theory, considering the honeycomb thin plate and thick plate respectively, the eigenvibration equation of composite honeycomb structure was solved by finite element method using the equivalence of temperature and humidity. A detailed model of composite honeycomb structure with four-edge clamped support was established by using finite element software ABAQUS. The effects of temperature, humidity, and combined temperature and humidity on the vibration characteristic of composite honeycomb thin plate and thick plate were discussed respectively. The numerical results show that compared with the increase of temperature, the natural frequencies of honeycomb structure are more sensitive to the increase of moisture concentration. Under the same humid and thermal environment, the natural frequency of the thick plate structure is larger than that of the thin plate, and the higher order of natural frequency, the greater the increase of natural frequency. The coupling effect of temperature and humidity has a greater effect on the natural frequency of composite honeycomb structure than the superposition of temperature and humidity when they act alone, and this effect is more obvious for the composite honeycomb thin plate.
2020, 37(7): 1611-1618.
doi: 10.13801/j.cnki.fhclxb.20190930.002
Abstract:
Taking the quartz/epoxy composite structure as the object, the global sensitivity theory was adopted to analyze the influences of the input parameters on the strength response of quartz/epoxy composite structure by considering the random characteristics of the input parameters. MATLAB and NASTRAN were combined to obtain the output response after considering all the input parameter randomness, then the adaptive Kriging model was introduced to construct the ultimate surrogate model. On basis of this surrogate model, the reliability of overall strength of the quartz/epoxy composite structure was computed, and the global sensitivity indices reflecting the influences of the input parameters on the output response were also obtained. The importance of the input parameters can be ranked according to the sensitivity results, which can provide guidance information for the design of composite structure.
Taking the quartz/epoxy composite structure as the object, the global sensitivity theory was adopted to analyze the influences of the input parameters on the strength response of quartz/epoxy composite structure by considering the random characteristics of the input parameters. MATLAB and NASTRAN were combined to obtain the output response after considering all the input parameter randomness, then the adaptive Kriging model was introduced to construct the ultimate surrogate model. On basis of this surrogate model, the reliability of overall strength of the quartz/epoxy composite structure was computed, and the global sensitivity indices reflecting the influences of the input parameters on the output response were also obtained. The importance of the input parameters can be ranked according to the sensitivity results, which can provide guidance information for the design of composite structure.
2020, 37(7): 1619-1628.
doi: 10.13801/j.cnki.fhclxb.20191107.002
Abstract:
A one-meter-level carbon fiber reinforced plastic(CFRP) composite antenna panel with the surface error less than 10 μm root-mean-square(RMS) has been trial-produced by using additional resin modification technology to satisfy the requirements of high frequency antenna reflector in submillimeter and terahertz wave band. The thermal deformation mechanisms of the high accuracy CFRP composite panel under extreme low temperature were studied. Based on the test data of the basic material, a finite element model was established to predict the thermal deformation residual error of the the panels considering different parameters under the condition of large temperature difference. The main factors affecting the thermal deformation characteristics of the panel were analyzed. The thermal deformation characteristics of the panels with aluminum honeycomb and CFRP composite tube array cores were compared, respectively, which shows that the higher specific stiffness and thermal stability are provided by the panel structure with CFRP composite tube array core. The structural design parameters of the prototype panel were given after the structural optimization, and the prototype panels were remanufactured. The thermal deformation residual errors of prototype panels with aluminum honeycomb and CFRP composite tube array cores were measured by the experimental method of high precision photogrammetry. The guidance for the design and process of high accuracy CFRP composite sandwiched panels was provided.
A one-meter-level carbon fiber reinforced plastic(CFRP) composite antenna panel with the surface error less than 10 μm root-mean-square(RMS) has been trial-produced by using additional resin modification technology to satisfy the requirements of high frequency antenna reflector in submillimeter and terahertz wave band. The thermal deformation mechanisms of the high accuracy CFRP composite panel under extreme low temperature were studied. Based on the test data of the basic material, a finite element model was established to predict the thermal deformation residual error of the the panels considering different parameters under the condition of large temperature difference. The main factors affecting the thermal deformation characteristics of the panel were analyzed. The thermal deformation characteristics of the panels with aluminum honeycomb and CFRP composite tube array cores were compared, respectively, which shows that the higher specific stiffness and thermal stability are provided by the panel structure with CFRP composite tube array core. The structural design parameters of the prototype panel were given after the structural optimization, and the prototype panels were remanufactured. The thermal deformation residual errors of prototype panels with aluminum honeycomb and CFRP composite tube array cores were measured by the experimental method of high precision photogrammetry. The guidance for the design and process of high accuracy CFRP composite sandwiched panels was provided.
2020, 37(7): 1629-1638.
doi: 10.13801/j.cnki.fhclxb.20190827.001
Abstract:
To investigate the axial compressive performance of fiber reinforced polymer (FRP) composite-confined ultra-high performance concrete (UHPC) cylindrical specimens, the meso-scale finite element model was established in LS-DYNA and validated by the comparison of the experimental data. The formula of shear dilation parameter of K&C model was proposed, which could accurately reflect the FRP composites confinement for UHPC. Based on the validated model, a parametric analysis was conducted to investigate the influence of FRP composite tube thickness, FRP composites fiber winding angle and steel fiber content. The results show that the model can not only capture the effect of random distributed steel fibers on the specimen stress distribution, but also accurately reflect the enhancement of strength and ductility of UHPC core subjected to FRP composite confinement. Good agreement is found in failure modes and stress-strain curves between simulation and experimental results. Parametric studies show that with the increase of FRP composite tubes thickness and FRP composite fiber winding angle, the strength and ductility of the FRP composite-confined UHPC specimens are significantly enhanced. An increase in steel fiber content can effectively restrain the inclined shear cracks in UHPC core, but has little effect on the strength and ductility of the specimens.
To investigate the axial compressive performance of fiber reinforced polymer (FRP) composite-confined ultra-high performance concrete (UHPC) cylindrical specimens, the meso-scale finite element model was established in LS-DYNA and validated by the comparison of the experimental data. The formula of shear dilation parameter of K&C model was proposed, which could accurately reflect the FRP composites confinement for UHPC. Based on the validated model, a parametric analysis was conducted to investigate the influence of FRP composite tube thickness, FRP composites fiber winding angle and steel fiber content. The results show that the model can not only capture the effect of random distributed steel fibers on the specimen stress distribution, but also accurately reflect the enhancement of strength and ductility of UHPC core subjected to FRP composite confinement. Good agreement is found in failure modes and stress-strain curves between simulation and experimental results. Parametric studies show that with the increase of FRP composite tubes thickness and FRP composite fiber winding angle, the strength and ductility of the FRP composite-confined UHPC specimens are significantly enhanced. An increase in steel fiber content can effectively restrain the inclined shear cracks in UHPC core, but has little effect on the strength and ductility of the specimens.
2020, 37(7): 1639-1648.
doi: 10.13801/j.cnki.fhclxb.20191107.001
Abstract:
The amino functionalized Fe3O4(NH2—Fe3O4) had been successfully prepared as magnetic core. With zinc nitrate hexahydrate (Zn(NO3)2·6H2O) as zinc source and polyethylene glycol(PEG, PEG-400) as surfactant, the magnetic composite based on zinc oxide and PEG-400-modified (NH2—Fe3O4@PEG@ZnO) composite was synthesized by hydrothermal process. The composition, morphology and magnetic properties of the NH2—Fe3O4@PEG@ZnO composite were characterized by a series of techniques including XRD, SEM, TEM, XPS, UV-VIS-NIR spectroscopy, specific surface area analyzer(BET), vibrating sample magnetometer(VSM) and so on. The photocatalytic performance of NH2—Fe3O4@PEG@ZnO composite under ultraviolet light was investigated by using the degradation of Rhodamine B (RhB) dye as a simulated pollutant. The influencing factors such as the atomic ratio of Fe to Zn(n(Fe)∶n(Zn)), reaction temperature, types and dosages of surfactant on photocatalytic degradation performance were investigated by one-factor method. The results show that NH2—Fe3O4@ZnO composite has good photocatalytic activity which is synthesized by n(Fe)∶n(Zn) is 1∶15 and the hydrothermal temperature is 180℃. The degradation rate of 50 mL RhB(1.0×10−5 mol·L−1) is 90.36% when use 0.0500 g NH2—Fe3O4@ZnO composite as a catalyst under ultraviolet light within 20 min. The specific surface area of NH2—Fe3O4@PEG@ZnO composite is 11.43 m2·g−1, the forbidden band width is about 2.51 eV and degradation rate of RhB is up to 99.36%. After 10 times of recycling, the photocatalytic degradation rate of RhB can still reach 96.48%. The combination of NH2−Fe3O4@ZnO composite and PEG-400 has a synergistic effect on improving the photocatalytic activity.
The amino functionalized Fe3O4(NH2—Fe3O4) had been successfully prepared as magnetic core. With zinc nitrate hexahydrate (Zn(NO3)2·6H2O) as zinc source and polyethylene glycol(PEG, PEG-400) as surfactant, the magnetic composite based on zinc oxide and PEG-400-modified (NH2—Fe3O4@PEG@ZnO) composite was synthesized by hydrothermal process. The composition, morphology and magnetic properties of the NH2—Fe3O4@PEG@ZnO composite were characterized by a series of techniques including XRD, SEM, TEM, XPS, UV-VIS-NIR spectroscopy, specific surface area analyzer(BET), vibrating sample magnetometer(VSM) and so on. The photocatalytic performance of NH2—Fe3O4@PEG@ZnO composite under ultraviolet light was investigated by using the degradation of Rhodamine B (RhB) dye as a simulated pollutant. The influencing factors such as the atomic ratio of Fe to Zn(n(Fe)∶n(Zn)), reaction temperature, types and dosages of surfactant on photocatalytic degradation performance were investigated by one-factor method. The results show that NH2—Fe3O4@ZnO composite has good photocatalytic activity which is synthesized by n(Fe)∶n(Zn) is 1∶15 and the hydrothermal temperature is 180℃. The degradation rate of 50 mL RhB(1.0×10−5 mol·L−1) is 90.36% when use 0.0500 g NH2—Fe3O4@ZnO composite as a catalyst under ultraviolet light within 20 min. The specific surface area of NH2—Fe3O4@PEG@ZnO composite is 11.43 m2·g−1, the forbidden band width is about 2.51 eV and degradation rate of RhB is up to 99.36%. After 10 times of recycling, the photocatalytic degradation rate of RhB can still reach 96.48%. The combination of NH2−Fe3O4@ZnO composite and PEG-400 has a synergistic effect on improving the photocatalytic activity.
2020, 37(7): 1649-1656.
doi: 10.13801/j.cnki.fhclxb.20191128.002
Abstract:
Carbon nanotubes(CNTs) and Ti3AlC2 reinforced phase was surface modified by electroless copper plating. The CNTs-Ti3AlC2/AZ91D composites was prepared by hot pressing (HP) sintering. The microstructure, mechanical properties and strengthening mechanism of the CNTs-Ti3AlC2/AZ91D composites were studied.The results indicate that the main physical phases in the CNTs-Ti3AlC2/AZ91D composite are CNTs, Ti3AlC2, Mg and Al12Mg17, and the reinforced phase is uniformly distributed in the matrix. There is a U phase (MgAlCu) at the interface between the reinforced phase and the matrix, which can make the interface of the two well combined. When the reinforced phase content is CNTs (1wt%) and Ti3AlC2 (25wt%), compared with magnesium alloyAZ91D, the elasticity modulus, tensile strength, yield strength and elongation of the CNTs-Ti3AlC2/AZ91D composites are increased by 120.30%, 25.72%, 126.50% and 36.84%, respectively, and the flexural strength and compression strength are 337.92 MPa and 436.27 MPa. The fracture mode of the CNTs-Ti3AlC2/AZ91D composites is brittle fracture, and the strengthening mechanism is mainly thermal mismatch strengthening, Orowan strengthening and fine grain strengthening.
Carbon nanotubes(CNTs) and Ti3AlC2 reinforced phase was surface modified by electroless copper plating. The CNTs-Ti3AlC2/AZ91D composites was prepared by hot pressing (HP) sintering. The microstructure, mechanical properties and strengthening mechanism of the CNTs-Ti3AlC2/AZ91D composites were studied.The results indicate that the main physical phases in the CNTs-Ti3AlC2/AZ91D composite are CNTs, Ti3AlC2, Mg and Al12Mg17, and the reinforced phase is uniformly distributed in the matrix. There is a U phase (MgAlCu) at the interface between the reinforced phase and the matrix, which can make the interface of the two well combined. When the reinforced phase content is CNTs (1wt%) and Ti3AlC2 (25wt%), compared with magnesium alloyAZ91D, the elasticity modulus, tensile strength, yield strength and elongation of the CNTs-Ti3AlC2/AZ91D composites are increased by 120.30%, 25.72%, 126.50% and 36.84%, respectively, and the flexural strength and compression strength are 337.92 MPa and 436.27 MPa. The fracture mode of the CNTs-Ti3AlC2/AZ91D composites is brittle fracture, and the strengthening mechanism is mainly thermal mismatch strengthening, Orowan strengthening and fine grain strengthening.
