1987 Vol. 4, No. 3
1987, 4(3): 1-Ⅰ.
Abstract:
A review is given of development of the metal matrix composite materials in China during the present time.Particular topics of introduction and discussion include the reinforcements,matrices and various species of metal matrix composites, the new fabrication techniques and applications as well as the research work dealing with the interface behaviors, mechanical properties and fracture process of the composites, especially for the Chinese literatures which involve in these topics are concerned.Suggestions regarding to the further development of metal matrix composites to realize its potential fully are also presented.
A review is given of development of the metal matrix composite materials in China during the present time.Particular topics of introduction and discussion include the reinforcements,matrices and various species of metal matrix composites, the new fabrication techniques and applications as well as the research work dealing with the interface behaviors, mechanical properties and fracture process of the composites, especially for the Chinese literatures which involve in these topics are concerned.Suggestions regarding to the further development of metal matrix composites to realize its potential fully are also presented.
1987, 4(3): 10-Ⅱ.
Abstract:
The dense C/Al composites have been fabricated by hot isostatic pressing (HIP) with which the C/Al precursor wires were encapsu-fated in a glass tube.It was observed that the fracture of the C/Al composite possesses a low strength and smoothness.The reaction layer of the interface was studied with scanning electron micro scope (SEM).The transmission electron microscope (TEM) and X-ray energy spectroscope (XES) were used to observe and determine the morphology and the composition of the interface.It was found that the interface was divided into two layers.TiB2 interface was diffused to the both sides of the interface and the compositions of the carbon fiber and matrix also were diffused through the interface. Beside sthe electron diffraction (ED) was used to study the inter-face structure.The structure compositions were defined as TiO2, TiC,TiB2,r-Al2O3, Ti, B and C.The chemical compositions were analyzed by auger electron spectroscopy (AES) and secondion masses spectroscopy (SIMS).The composition determined were used by SIMS and ED with a nearly result except founding Al4C3 at SIMS.
The dense C/Al composites have been fabricated by hot isostatic pressing (HIP) with which the C/Al precursor wires were encapsu-fated in a glass tube.It was observed that the fracture of the C/Al composite possesses a low strength and smoothness.The reaction layer of the interface was studied with scanning electron micro scope (SEM).The transmission electron microscope (TEM) and X-ray energy spectroscope (XES) were used to observe and determine the morphology and the composition of the interface.It was found that the interface was divided into two layers.TiB2 interface was diffused to the both sides of the interface and the compositions of the carbon fiber and matrix also were diffused through the interface. Beside sthe electron diffraction (ED) was used to study the inter-face structure.The structure compositions were defined as TiO2, TiC,TiB2,r-Al2O3, Ti, B and C.The chemical compositions were analyzed by auger electron spectroscopy (AES) and secondion masses spectroscopy (SIMS).The composition determined were used by SIMS and ED with a nearly result except founding Al4C3 at SIMS.
1987, 4(3): 15-Ⅱ.
Abstract:
Fabrication technique of discontinous carbon fiber reinforced copper-5%tin matrix materials was studied.The Carbon fiber was well composited with the copper and tin powder without pressing. The dense composites with the carbon fiber volume content ranging from 10% to 50% were made in the given technology.The fiber homogeneously distributed in the matrix and has a random orientation.The properties of the composites such as hardness, electric resistance, coefficient bending strength, tribological behavior were tested and the effect of the fiber content on the properties of the materials were also disscaussed.Furthermore, the bending fracture and wearing surface were observed by the use of scanning electron microscope.
Fabrication technique of discontinous carbon fiber reinforced copper-5%tin matrix materials was studied.The Carbon fiber was well composited with the copper and tin powder without pressing. The dense composites with the carbon fiber volume content ranging from 10% to 50% were made in the given technology.The fiber homogeneously distributed in the matrix and has a random orientation.The properties of the composites such as hardness, electric resistance, coefficient bending strength, tribological behavior were tested and the effect of the fiber content on the properties of the materials were also disscaussed.Furthermore, the bending fracture and wearing surface were observed by the use of scanning electron microscope.
1987, 4(3): 23-Ⅳ.
Abstract:
The fracture mechanism of composite metallic materials and the strengthening function of fibres are the important subjects worth studing.Recently, much attention has been paid to the fracture processes of metallic matrix composites. However,due to the lack of observations made directly during the deformation and f racture processes, it has been difficult to know exactly The mechanism of initiation and propagation of microcracks.The purpose of this paper is to investigate the fracture processes in Boron fibre reinforced Aluminium (B/Al) composites by using the in-situ technique in a scanning electrow microscope (SEM) and on the basis of observations mentioned above to analyze the mechanism of microcrack initiation and propagation in these composites.
The fracture mechanism of composite metallic materials and the strengthening function of fibres are the important subjects worth studing.Recently, much attention has been paid to the fracture processes of metallic matrix composites. However,due to the lack of observations made directly during the deformation and f racture processes, it has been difficult to know exactly The mechanism of initiation and propagation of microcracks.The purpose of this paper is to investigate the fracture processes in Boron fibre reinforced Aluminium (B/Al) composites by using the in-situ technique in a scanning electrow microscope (SEM) and on the basis of observations mentioned above to analyze the mechanism of microcrack initiation and propagation in these composites.
1987, 4(3): 32-Ⅴ.
Abstract:
The manufacturing process for the metal matrix composites of SiC whisker/aluminum alloy is being developed.The process consists of the fabrication of the whisker's preform and the fabrication of the composite billet by liquid metal infiltration.In this way the composites with 17% volume fraction of SiC whisker are manufactured.
The manufacturing process for the metal matrix composites of SiC whisker/aluminum alloy is being developed.The process consists of the fabrication of the whisker's preform and the fabrication of the composite billet by liquid metal infiltration.In this way the composites with 17% volume fraction of SiC whisker are manufactured.
1987, 4(3): 40-Ⅵ.
Abstract:
It is very important to study the impact behavior of composite for the developing investfgation and use of composite.The specimens used here were different kinds of composite wires which were fabricated by means of the Ti-B (CVD) coated carbon and graphite fiber then infiltrating with the liquid Al alloy.The methods of heat exposure at different temperature in vacuum and thermal cycling between room temperature and 4500C have been used to change the composite interfacial bonding state.It is found that there are close relation between interfacial bonding state and impact energy.The impact energy could be increased by the way of slacking the interfacial bonding state.With the help of the micrograph of the impact fracture surface, it is found that matrix deformation, fiber pulling-out,debonding and inteafacial friction between fiber and matrix, as well as surface energy are important energy absored mechanism.
It is very important to study the impact behavior of composite for the developing investfgation and use of composite.The specimens used here were different kinds of composite wires which were fabricated by means of the Ti-B (CVD) coated carbon and graphite fiber then infiltrating with the liquid Al alloy.The methods of heat exposure at different temperature in vacuum and thermal cycling between room temperature and 4500C have been used to change the composite interfacial bonding state.It is found that there are close relation between interfacial bonding state and impact energy.The impact energy could be increased by the way of slacking the interfacial bonding state.With the help of the micrograph of the impact fracture surface, it is found that matrix deformation, fiber pulling-out,debonding and inteafacial friction between fiber and matrix, as well as surface energy are important energy absored mechanism.
1987, 4(3): 45-Ⅴ.
Abstract:
This paper deals with carbon(graphite)fiber/aluminum composite materials under the thermal cycling condition, to observe the influence on the tensile strength of composites.It is considered that the strength could be changed by the variation of interfacial bonding caused by the thermal stress of the cycling process.The specimens used werefour kinds of C (Cir) /Al wires, which were fabricated by means of Ti-B (CVD) coated fibers and infilitrating with liquid Al alloys(Al-Si and LD2).The tensile strength have been measured after thermal cycling treated in temperature range of R.T.to 4500C for various times.The effects of thermal cycling on the tensile strength of composites were discussed with the micrograph of the fracturesurface. It was indicated that the changes of tensile strength wererelated to the changes of interfacial bonding strength, and there was an optimal state of interface bond which corresponds to providing the maximum tensile strength for each composites according to the different constituents and fabrication processes.
This paper deals with carbon(graphite)fiber/aluminum composite materials under the thermal cycling condition, to observe the influence on the tensile strength of composites.It is considered that the strength could be changed by the variation of interfacial bonding caused by the thermal stress of the cycling process.The specimens used werefour kinds of C (Cir) /Al wires, which were fabricated by means of Ti-B (CVD) coated fibers and infilitrating with liquid Al alloys(Al-Si and LD2).The tensile strength have been measured after thermal cycling treated in temperature range of R.T.to 4500C for various times.The effects of thermal cycling on the tensile strength of composites were discussed with the micrograph of the fracturesurface. It was indicated that the changes of tensile strength wererelated to the changes of interfacial bonding strength, and there was an optimal state of interface bond which corresponds to providing the maximum tensile strength for each composites according to the different constituents and fabrication processes.
1987, 4(3): 51-Ⅶ.
Abstract:
The friction and wear characteristics of Al-graphite particle composites prepared by a new method using a graphite rich master alloy were evaluated with a pin-on-disc machine under high temperature condition at the sliding speed up to 9.4m/sec.At the sliding speed of 2m/sec under dry condition the wear rates of all the composites tested were lower than the matrix.At 200℃, the wear rates of the composites containing 2-5% graphite decreased.At the sliding speed of 9.4m/sec the composite containing 2% graphite was the moat wear resistant of the composites and alloys studied.It was reported before that the friction coefficients and wear rates of Algraphite particle composites were higher than the matrix when the sliding speed was greater than 1 m/sec[12, 13].The reduction in wear rates and friction coefficients of the composites at high sliding speed of 9.4m/sec with respect to the matrix alloy wear was attributed to the strong graphite-matrix interfacial bond of the composites prepared by the new method.
The friction and wear characteristics of Al-graphite particle composites prepared by a new method using a graphite rich master alloy were evaluated with a pin-on-disc machine under high temperature condition at the sliding speed up to 9.4m/sec.At the sliding speed of 2m/sec under dry condition the wear rates of all the composites tested were lower than the matrix.At 200℃, the wear rates of the composites containing 2-5% graphite decreased.At the sliding speed of 9.4m/sec the composite containing 2% graphite was the moat wear resistant of the composites and alloys studied.It was reported before that the friction coefficients and wear rates of Algraphite particle composites were higher than the matrix when the sliding speed was greater than 1 m/sec[12, 13].The reduction in wear rates and friction coefficients of the composites at high sliding speed of 9.4m/sec with respect to the matrix alloy wear was attributed to the strong graphite-matrix interfacial bond of the composites prepared by the new method.
1987, 4(3): 57-Ⅶ.
Abstract:
Experiments and studies of the compatibility of carbon fibre with some metals, such se Cu, Ca and Fe, have been made.After vacuum heat treatment, the changes in appearance of coatings, atructure and strength of electroplated carbon fibre were investigated by tensile test, X-ray dif fraction, microphotography and scanning election microfractography, arid some mechanisms of interaction between carbon fibre and metals were also developed.The paper tried to provide preliminary basis of experiments and analyses for the possibilities in using Cu, Co and Fe as the coatings and matrixes for carbon fibres.
Experiments and studies of the compatibility of carbon fibre with some metals, such se Cu, Ca and Fe, have been made.After vacuum heat treatment, the changes in appearance of coatings, atructure and strength of electroplated carbon fibre were investigated by tensile test, X-ray dif fraction, microphotography and scanning election microfractography, arid some mechanisms of interaction between carbon fibre and metals were also developed.The paper tried to provide preliminary basis of experiments and analyses for the possibilities in using Cu, Co and Fe as the coatings and matrixes for carbon fibres.
1987, 4(3): 68-Ⅷ.
Abstract:
It is important to find out that the effect of the interfacial reaction and the properties of carbon/aluminum strong interface bonding brittle interface layer,and then the rainforced fiber damage.In order to get various status of interface reactions, thermal exposure was used.By use of a scanning electron microscope and analysis of the reaction product (Al4C3)the status of interfacial bonding was determined.It is shown that the strength of interface bonding and the thickness of the brittle layer mainly affect the crack propagating method in the loading process of composites. When the interface bonding is stiong, the crack propagates across the fiber so that the strength of composites was decreased.When the bonding is weak, the crack propagates along the fiber surface and the fiber is pulled out, so the strength was increased.As a crack source, the brittle interface layer that has a harmful thickness may lead to fracture of composites below the theoretical strength (ROM).Otherwise the brittle layer can be a throughway for quickly crack propagating.When the temperature of thermal exposure exceed 650℃, the stronger interface reaction occurs and the rainforced fiber may be damaged, and therefore the strength of the composite decreased rapidly.
It is important to find out that the effect of the interfacial reaction and the properties of carbon/aluminum strong interface bonding brittle interface layer,and then the rainforced fiber damage.In order to get various status of interface reactions, thermal exposure was used.By use of a scanning electron microscope and analysis of the reaction product (Al4C3)the status of interfacial bonding was determined.It is shown that the strength of interface bonding and the thickness of the brittle layer mainly affect the crack propagating method in the loading process of composites. When the interface bonding is stiong, the crack propagates across the fiber so that the strength of composites was decreased.When the bonding is weak, the crack propagates along the fiber surface and the fiber is pulled out, so the strength was increased.As a crack source, the brittle interface layer that has a harmful thickness may lead to fracture of composites below the theoretical strength (ROM).Otherwise the brittle layer can be a throughway for quickly crack propagating.When the temperature of thermal exposure exceed 650℃, the stronger interface reaction occurs and the rainforced fiber may be damaged, and therefore the strength of the composite decreased rapidly.
1987, 4(3): 74-Ⅸ.
Abstract:
The tensile strength of carbon fiber/LD2 aluminum alloy (C/LD2). and graphite M40/LD2 aluminum alloy (bI40/LD2) composites at high.temperature has preliminarily investigated.Carbon fiber(C), graphite fiber (M40) and Al foil (LD2) are used as the components of composites.The C or M40/Al composite wires are fabricated by means of C.V.D.Ti-B coating on the fibers and then infiltrated with the molten aluminum alloy. The C or M40/LD2 unidirectional composite plates are prepared by partial-liquid phase hot pressing method.Experimental results have shown that the Al4C3 content in C/LD2 specimen is larger than that of M40/LD2.On the contrary the tensile of M40/LD2 is higher than C/LD2.But both M40/LD2 and C/LD2 composites retain the tensile strength from room temperature up to 400℃ in nearly same level.The tensile strength maintenance ratio of C/LD2 is about 84%.
The tensile strength of carbon fiber/LD2 aluminum alloy (C/LD2). and graphite M40/LD2 aluminum alloy (bI40/LD2) composites at high.temperature has preliminarily investigated.Carbon fiber(C), graphite fiber (M40) and Al foil (LD2) are used as the components of composites.The C or M40/Al composite wires are fabricated by means of C.V.D.Ti-B coating on the fibers and then infiltrated with the molten aluminum alloy. The C or M40/LD2 unidirectional composite plates are prepared by partial-liquid phase hot pressing method.Experimental results have shown that the Al4C3 content in C/LD2 specimen is larger than that of M40/LD2.On the contrary the tensile of M40/LD2 is higher than C/LD2.But both M40/LD2 and C/LD2 composites retain the tensile strength from room temperature up to 400℃ in nearly same level.The tensile strength maintenance ratio of C/LD2 is about 84%.
1987, 4(3): 78-Ⅸ.
Abstract:
The fracture of the carbon fiber reinforced plumbum matrix composites in axial tensile was observed by the use of electron scanning microscopy.The character of the crack initiation and propagation of the composites was identified.The main factor which affects on the tensile fracture of the C/Pb composites was given.
The fracture of the carbon fiber reinforced plumbum matrix composites in axial tensile was observed by the use of electron scanning microscopy.The character of the crack initiation and propagation of the composites was identified.The main factor which affects on the tensile fracture of the C/Pb composites was given.
1987, 4(3): 84-Ⅸ.
Abstract:
This Paper deals with the corrosion behavior of C/Al composite manufactured by Na-K method.A comparison is made between the corrosion behavior and that of the composite manufactured by CVD method.Immersed in either distilled water or 3.5% salt solution for 14 days, two kinds of materials metioned above corroded all severely.A rough surface has harmful effects on the corrosion of composites. The exposure to air for a long lime will result in the corrosion of the composites at defect zones (grain boundary, C-Al interface etc.).
This Paper deals with the corrosion behavior of C/Al composite manufactured by Na-K method.A comparison is made between the corrosion behavior and that of the composite manufactured by CVD method.Immersed in either distilled water or 3.5% salt solution for 14 days, two kinds of materials metioned above corroded all severely.A rough surface has harmful effects on the corrosion of composites. The exposure to air for a long lime will result in the corrosion of the composites at defect zones (grain boundary, C-Al interface etc.).
