SiC Volume Research Articles

Preparation of Al/SiC Composite Coatings on Surface of Aluminum Alloy by Atmospheric Plasma Spraying

Abstract Al/SiC composite coatings were deposited on the surface of aluminum alloy by atmospheric plasma spraying. The effects of SiC volume in Al/SiC composite powders on the deposition behavior and the properties of the Al/SiC coatings were investigated. It is found that the decarburization and oxidation of pure SiC powder occur in the plasma flame. With the increase of SiC content, the deposition of the Al/SiC composite powder becomes more difficult through plasma spraying. There exist cracks between the bond coat and the aluminum alloy substrate resulting in poor adhesion between them. The hardness of the composite coating becomes higher with the increase of SiC content. The Al/SiC (50:50) deposit with a thickness of 70 μm and a hardness of 3690 MPa can strengthen the surface of aluminum alloy.

Syntheses of ZrC–SiC nanopowder via sol–gel method

ZrC–SiC composite nanopowder is synthesized via a simple sol–gel process. First, stable precursor sols are prepared from zirconium oxychloride and tetraethoxysilane respectively. Two sols are mixed and sucrose is added as the carbon source. The mixed precursor sol is converted to ZrC–SiC composite nanopowders after ceramic conversion at 1500°C for 1h under vacuum. The particle sizes of the as-synthesized ZrC–SiC composite powders are strongly affected by their compositions. It appears that the coexistences of silica and zirconia hinder the particle growth, leading to smaller and more uniform products. Particles of an average diameter at 180nm are obtained when SiC volume content is around 12%. The powders are systematically characterized by XRD, SEM, TEM, TG-DSC and TEM-EDS.

An investigation on the aging responses and corrosion behaviour of A356/SiC composites by neural network: The effect of cold working ratio

In the present study, an artificial neural network model has been used for predicting the corrosion behaviour, aging and hardness responses of aluminium-based metal matrix composites reinforced with silicon carbide particle. Hyperbolic tangent sigmoid and linear activation functions are employed as the most appropriate activation function for hidden and output layers, respectively. The developed artificial neural network model is used to predict the corrosion current density, peak aging time and peak hardness of the composites. Feed forward back propagation neural network has been trained by Levenberg Marquardt algorithm. The regression correlation coefficients ( R2) between the predicted and the experimental values of the corrosion current densities are found as 0.99986, 0.99629 and 0.99671 for the training, testing and validation datasets, respectively. Also, some case studies have been predicted by artificial neural network model. Test results indicate that the proposed network can be used efficiently for the prediction of the polarization response, peak aging time and peak hardness of the composites for different SiC volume fractions and deformation ratio without using any experimental data.

SIC volume 28 issue 3 Cover and Back matter

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SIC volume 28 issue 3 Cover and Front matter

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Sic-Reinforced Aluminum-Silicon Composite via Pressureless Infiltration Using Polystyrene as External Binder for Electronic Assemblies

SiC-reinforced aluminum composite was developed by pressureless infiltration technique using polystyrene as external binder. The metal matrix composites obtained were characterized for phase composition, microstructure, density, porosity, hardness and thermal expansion. The SiC particles were uniformly distributed within the Al-Si matrix with the help of polystyrene as external binder. The variation in the density of the composites was found to be linear with volume percent of SiC. The hardness increased with increasing SiC content and highest hardness was 64.52 HV achieved with addition of 20 vol.% SiC. Thermal conductivity of the composites increased with increasing of SiC volume fraction up to 27.34 W/mK.

Properties of SiC particulate preforms based on different pore-forming agents and bonding methods for making SiC/Al composites

The preforms with high SiC volume fraction (>50%) were successfully fabricated by two bonding methods. Moreover, the dimensional change, compressive strength, and microstructure of SiC preforms were investigated, and the bonding mechanism among SiC particulates in preforms was also discussed. Results show that, after heating to 1 100 °C and holding for 2 h, a uniform and interconnected structure in the SiC preforms can be obtained by using starch, stearic acid, and graphite respectively as the pore-forming agents, which benefits the subsequent infiltration by the molten metals. More neck-like-jointing among SiC particulate by using graphite as the pore-forming agent improves the dimensional accuracy and compressive strength of the preform. Besides, the properties of the preforms by the binder bonding are better than those by the oxidation bonding, which is mainly because the mixed neck-like-jointing and binder at high temperature provide effective bonding together.

SIC volume 28 issue 2 Cover and Back matter

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SIC volume 28 issue 2 Cover and Front matter

SIC volume 28 issue 2 Cover and Front matter

Influence of particle size distribution on properties of SiC particles reinforced aluminum matrix composites with high SiC particle content

In this paper, 60.5–68.0 vol.% SiCp/Al composites were prepared by infiltrating liquid aluminum into preforms. The average diameters of SiC particles used in the particles packing experiments were 45, 8 and 2 µm for the group I preforms, and 75, 8 and 2 µm for the group II preforms. The thermal-mechanical properties of the composites were investigated. The mechanical properties test showed that the tensile strength of the composites was in the range of 212–349 MPa, and the elastic modulus of the composites was greater than 150 GPa. For a given SiC volume fraction, the tensile strength and elastic modulus of the group I composites were greater than that of the group II composites. The thermal properties test revealed that the coefficient of thermal expansion of the composites was in the range of 10.33–12.32 × 10–6/℃, and the measured thermal conductivity of the composites was greater than 85.6 W/(m·℃). The change of the particle size distribution had no effect on the coefficient of thermal expansion, and the coefficient of thermal expansion decreased linearly with the increase of SiC content. An average diameter approach for estimating the thermal conductivity of the composites was proposed in the application of Hasselman-Johnson model. The results indicated that the predictions of the model were in good agreement with the measured thermal conductivity of the composites.

Erosive behaviors of SiC foam/epoxy co-continuous phase composites

SiC foam/epoxy co-continuous phase composites (SiCfoam/EPs) that were composed of the E-51 epoxy (EP) matrix and the SiC ceramic foam (SiCfoam) reinforcement were prepared as the erosion resistant materials. The erosive behaviors of SiCfoam/EPs were investigated by using a rotating disk rig. The effects of sand content (C), flow velocity (V), test duration and SiC volume fraction on the erosive behaviors of SiCfoam/EPs were studied through the mass loss test, SEM and CLSM (Confocal Laser Scanning Microscope) observations. Under different experimental conditions, the erosion rate (Er, defined as the ratio of erosion (Ec) and time) was relatively larger before the transition point, but Er clearly decreased after the transition point. Ec of SiCfoam/EPs increased with flow velocity (Ec∝V3) and sand content (Ec∝C). The erosion angle (α, the angle between the eroded and initial surfaces) of SiCfoam/EPs increased linearly with flow velocity and sand content. Under the test conditions, flow velocity was the dominant factor for the erosive behaviors of SiCfoam/EPs. Ec and α of SiCfoam/EPs both decreased with the increase of SiC volume fraction. The erosion of SiCfoam/EPs obeyed the linear rule of mixtures (LROM) averaging law since EP and SiCfoam were eroded by a parallel process.

Microstructure and mechanical properties of the rheoformed cylindrical part of 7075 aluminum matrix composite reinforced with nano-sized SiC particles

Abstract The microstructure and mechanical properties of the rheoformed parts of 7075 aluminum matrix composite were investigated. The results show that more liquid phase and spheroidal solid grains were found in the microstructures in the top and medium regions of the side wall of the rheoformed parts due to dependence of the deformation on liquid flow and flow of liquid incorporating solid grains. Yield strength and ultimate tensile strength of the rheoformed composite parts are enhanced as compared with the as-extruded and the rheoformed parts of 7075 matrix alloy. The yield strength, ultimate tensile strength and elongation of the rheoformed composite parts with T6 reach 399 MPa, 492 MPa and 9.6%, respectively. When stirring time increases from 5 min to 20 min, the mechanical properties increased due to fine-grained strengthening and a further increase more than 20 min led to a slight change. Pressure led to a significant increase of the mechanical properties due to some reduction of defects and dislocations strengthening. An increase of SiC volume fraction from 0.5% to 1% led to an improvement of yield strength and ultimate tensile strength and a further increase led to a decrease.

Microstructure and Tribological Properties of Aluminum Matrix Composite

AlSi5Cu2 alloy matrix composite have been studied by microscopic examination and basic tribological properties was evaluated. Composite material was produced by the mechanical milling and spark plasma sintering technique. After sintering process SiC particles were uniformly distributed in the matrix. The wear and the friction coefficients were determinate as a function of the SiC volume fraction. The addition of SiC wt. % had significant effect on tribological properties of that composites. The increase in reinforcement content improves the wear resistance of obtained materials.

Flow stress behavior and processing map of extruded 7075Al/SiC particle reinforced composite prepared by spray deposition during hot compression

Hot compression tests of the extruded 7075Al/15%SiC (volume fraction) particle reinforced composite prepared by spray deposition were performed on Gleeble–1500 system in the temperature range of 300–450 °C and strain rate range of 0.001–1 s−. The results indicate that the true stress–rue strain curve almost exhibits rapid flow softening phenomenon without an obvious work hardening, and the stress decreases with increasing temperature and decreasing strain rate. Moreover, the stress levels are higher at temperature below 400 °C but lower at 450 °C compared with the spray deposited 7075Al alloy. Superplastic deformation characteristics are found at temperature of 450 °C and strain rate range of 0.001–.1 s− with corresponding strain rate sensitivity of 0.72. The optimum parameters of hot working are determined to be temperature of 430–50 °C and strain rate of 0.001–.05 s− based on processing map and optical microstructural observation.

Electroless copper plating on particulate reinforcements and effects on mechanical properties of SiCp/Fe composite

The electroless copper plating process on the powder of SiC has been investigated. Thickness of the coating was tailored by the amount of copper salt added in the bath with a molar ratio of 4∶1 between reducing agent of sodium hypophosphite and copper salt. It is also found that mixed complexing agent improves the smoothness of the coating surface. Compared with mechanical properties of the SiCp/Fe composites with and without copper coating, it is shown that the copper coating improves the tensile strength by 12·6% and the final elongation by 18·1% with the SiC volume fraction of 20%. Moreover, further investigation shows that the copper coating has a same effect on the tensile strength improvement as a similar nickel coating process but has a significantly better effect on improvement of the final elongation of the composite.

SIC volume 28 issue 1 Cover and Front matter

SIC volume 28 issue 1 Cover and Front matter

SIC volume 28 issue 1 Cover and Back matter

SIC volume 28 issue 1 Cover and Back matter

Properties of SiCp/6061-Al metal matrix composites prepared by infiltrating molten aluminum into ternary packing of SiC preforms

SiC particles reinforced aluminum matrix composites (SiCp/Al) with SiC content of more than 60%, without particle segregation for mirror substrate applications, are prepared by using the improved process. The improved process contains sintering process design, preform quality traceability, and equipment designing. The maximum SiC volume fraction of 70.4% is obtained by optimizing the selection of the following proportion: 71.4% coarse, 7.1% medium, and 21.5% fine particles. The variation of SiC volume fraction is correlated with the percentage of fine particles by using regression analysis. The preforms with the compressive strength above 10.34 MPa are prepared by sintering at 1600℃ for 2 h. Results showed that no defects in the scale of more than 10 µm are observed in the preforms. Due to the generation of a SiO2 layer during the sintering process, the formation of Al4C3 phase was inhibited. As the SiC particle volume fraction increased from 65.6% to 70.4%, the bending strength increased from 483.2 MPa to 585.2 MPa. The elastic modulus also increased from 174.2 GPa to 206.1 GPa, while the coefficient of thermal expansion between 50℃ and 350℃ decreased from 11.02 × 10−6/℃ to 9.53 × 10−6/℃.

Prediction of corrosion susceptibilities of Al-based metal matrix composites reinforced with SiC particles using artificial neural network

In this theoretical study, the prediction of the corrosion resistance of Al–Si–Mg-based metal matrix composites reinforced with SiC particles has been studied, using an artificial neural network. Four input vectors were used in the construction of the proposed network; namely, volume fraction of SiC reinforcement, aging time of the composites, environmental conditions, and potential. Current was used as the one output in the proposed network. Test results indicate that the proposed network can be used efficiently for the prediction of the corrosion resistance of Al–Si–Mg-based metal matrix composites reinforced with SiC particles, and the methodology is suitable for engineers to study the corrosion of metal matrix composites. In addition, a few forecasts regarding the polarization response for different SiC volume fractions and aging conditions have also been generated without using any experimental data.

Preparation and Performance of SiC Foam Ceramic/Fe Matrix Co-continuous Phase Composites

SiC foam ceramic/Fe based co-continuous phase composites were prepared by squeeze casting method using oxidized SiC foam ceramic.Then the prepared composites were annealed.The influence of preparation process and SiC volume fraction on microstructures and mechanical properties of the composites were investigated.Results show that a SiO2 barrier film of 1 mm in thickness on the surfaces of SiC foam can form after oxidizing at 1250°C for 48 h,which then can efficiently prevent the formation of a brittle intermetallic compound Fe3 Si at the interface of Fe matrix and SiC during the preparation of composites.As a result,the flexural strength of composites was increased by 100% and compressive strength by 18%.The thickness of SiO2 film was increased after oxidizing at 1250°C for 72 h,and a thicker SiO2 film may induce mismatch of thermal expansion coefficient between SiO2,Fe and SiC,which thereby resulted in the increase of residual stress.Therefore,the mechanical properties of composites were decreased slightly.The residual stress could be relieved after annealing of composites at 600°C for4 h,which improved the mechanical properties of composites.The function of bridging and deflecting crack of metal matrix is big for the composite with small SiC volume fraction,which is in turn beneficial to the enhancement of the flexural strength and flexural strain.For the composite with the higher SiC volume fraction,the size of SiC skeleton became bigger and the load- carrying capacity was strengthened,thereby its compressive strength was increased.