SiC Volume Fraction Research Articles

Thermoelectric Properties of Ni 0.05 Mo 3 Sb 5.4 Te 1.6 with Embedded SiC and Al 2 O 3 Nanoparticles

First, a large sample of Ni0.05Mo3Sb5.4Te1.6 was prepared by heating the elements in the stoichiometric ratio. β-SiC nanoparticles were added in volume fractions, f, of 0.01, 0.02, and 0.034 to three different portions of the material, and a portion without SiC nanoparticles was retained as a reference. All four samples were subjected to consolidation by hot-pressing. Furthermore, Al2O3 nanoparticles were added in volume fractions of f = 0.01, 0.0216, and 0.0325 to three other portions, again retaining a fourth protion as reference. These four samples were consolidated by spark-plasma sintering. The thermoelectric transport properties of these composites were characterized from 325 to 740 K. For the sample with 0.01 volume fraction of SiC, there was an enhancement in figure of merit by 18 % compared with the reference sample, mainly due to an 18 % reduced thermal conductivity. The 9 % reduction in thermal conductivity of the sample with 0.01 volume fraction of Al2O3 was not enough to compensate the loss in the power factor of 18 %, leading to a decrease in the figure of merit. Microstructural information obtained by SEM, TEM, and BET was used to elucidate the phase and transport properties. The spark-plasma-sintered bulk sample has a figure of merit that is 35 % higher than the bulk sample consolidated through hot-pressing.

Effects of reciprocating extrusion process on mechanical properties of AA 6061/SiC composites

A reciprocating extrusion (RE) process was used to improve the mechanical properties of Al-based composite manufactured using cast and powder metallurgy (PM). AA 6063 cast and AA 6061 powders were used as the matrix materials, and the matrix was reinforced by 5% SiC (volume fraction) particles. The hardness and grain size of extruded samples decrease with increasing the number of extrusion pass, while the toughness and ductility increase. As the tensile strength of the samples decreases, the elongation of the extruded samples increases. Consequently, reciprocating extrusion is an effective method for improving the mechanical properties of metal matrix composites (MMC).

Surface Integrity of AlSiC Composites Ground by Monolayer Brazed Diamond Wheels

Monolayer brazed diamond wheel were used to grind AlSiC composite with different volume fraction of SiC. The effects of diamond mesh size of the grinding wheels and the volume fraction of SiC in AlSiC composite on the surface integrity of ground AlSiC composite were investigated. It is found that the surface roughness of ground AlSiC composite with 20% SiC is increased with the reduction of diamond grit’s size because of the clogging of diamond wheel. With the increasing of the volume fraction of SiC, there are more fractured and cracked SiC particles on the ground surface of AlSiC composite. On the other hand, the finer diamond grits (70/80) induce the finer fractured SiC particles on the ground surface of AlSiC with 50% and 70% SiC.

Hot Deformation Behaviour of SiC/AA6061 Composites Prepared by Spark Plasma Sintering

In this study, SiC/AA6061 composites with different SiC volume fractions (5%, 10%, 15% and 20%) were fabricated by spark plasma sintering. The deformation behaviour of the composites was studied by uniaxial compression test at temperatures from 573 K to 773 K and strain rates between 0.001 s−1 and 1 s−1. Results indicate that the flow stress of SiC/AA6061 composites increases with the increase of SiC volume fraction, with the decrease of deformation temperature and with the decrease of strain rate. The main deformation mechanism of the composites is dynamic recrystallisation (DRX), and the DRX degree depends on the processing parameters of deformation. Higher SiC volume fraction, higher deformation temperature and lower deformation strain rate promote the occurrence of DRX. The strain rate sensitivity and deformation activation energy of SiC/AA6061 composites are calculated. Results show that with the increase in deformation temperature and the decrease in SiC volume fraction, the strain rate sensitivity of the composites increases. From 573 K to 773 K, the average deformation activation energy of 5vol.%SiC/AA6061, 10vol.%SiC/AA6061, 15vol.%SiC/AA6061 and 20vol.%SiC/AA6061 are 207.91, 230.88, 237.7 and 249.87 kJ mol−1, respectively. The optimum hot working zone of the SiC/AA6061 composites is in the temperature range of 723 K to 773 K at strain rates from 0.1 s−1 to 1 s−1.

Surface Integrity of AlSiC Composites Ground by Monolayer Brazed Diamond Wheels

Monolayer brazed diamond wheel were used to grind AlSiC composite with different volume fraction of SiC. The effects of diamond mesh size of the grinding wheels and the volume fraction of SiC in AlSiC composite on the surface integrity of ground AlSiC composite were investigated. It is found that the surface roughness of ground AlSiC composite with 20% SiC is increased with the reduction of diamond grit’s size because of the clogging of diamond wheel. With the increasing of the volume fraction of SiC, there are more fractured and cracked SiC particles on the ground surface of AlSiC composite. On the other hand, the finer diamond grits (70/80) induce the finer fractured SiC particles on the ground surface of AlSiC with 50% and 70% SiC.

Optimization of Surface Roughness in Turning Operation Using Firefly Algorithm

Recently, Firefly Algorithm (FA) has become an important technique to solve optimization problems. Various FA variants have been developed to suit various applications. In this paper, FA is used to optimize machining parameters such as % Volume fraction of SiC (V), cutting speed (S), feed rate (F), depth of cut (D) and machining time (T). The optimal machining cutting parameters estimated by FA that lead to a minimum surface roughness are validated using ANOVA test.

Microstructures and mechanical properties of AA6061–SiC composites prepared through spark plasma sintering and hot rolling

In this study, AA6061–SiC composites were synthesized through spark plasma sintering and hot rolling. The microstructures of these composites exhibited excellent SiC particle distribution in the AA6061 matrices, high dislocation density, and ultrafine Al matrix grain. The AA6061–SiC composites strengthened with increasing amounts of SiC particles. The yield strength, ultimate tensile strength, and elasticity modulus of the composites were 373MPa, 414MPa, and 95GPa, respectively, when the volume fraction of SiC was 20%. The composites exhibited dislocation, grain boundary, and secondary phase strengthening. The ductility of the composites decreased with increasing amounts of SiC particles, and the fracture mode was ductile.

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-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 and Al2O3 Reinforced Aluminum Metal Matrix Composites for Heavy Vehicle Clutch Applications

Aluminium metal matrix composite is one of the most promising engineering material and gradually emerging technology in automobile industries. There are usage of this composite material in certain critical applications like clutch pressure and face plate assembly due to their enhanced mechanical, wear and physical properties. In the present study, A356 aluminum alloy reinforced with SiC and Al2O3 particle was made by stir casting process. The effects of different volume fractions of SiC and Al2O3 particle reinforcement on microstructure and mechanical properties have been investigated. The tensile, yield strength and hardness have been increased in the particulate containing composites. As compared to base alloy, 20 % volume fraction of SiC reinforced composites showed 16 % increase in tensile strength and 10 % volume fraction of Al2O3 reinforced composites showed 19 % increase in tensile strength. The yield strength of 20 % SiC and 10 % Al2O3 containing samples nearly 50 % higher than those of the base alloy. Dislocation density, precipitation hardening and changes in grain size are the main mechanisms enhancing the mechanical properties of particulate reinforced composites. The 20 % SiC and 10 % Al2O3 reinforced composites have been identified as optimized composites for clutch pressure/face plate application.

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.

A study on chip shape and chip-forming mechanism in grinding of high volume fraction SiC particle reinforced Al-matrix composites

In order to solve the precision machining problem existing in the high volume fraction SiCp/Al composites with high integrity surface, chip shape and chip-forming mechanism were researched. Surface grinding experiments were carried out on the higher volume fraction SiCp/Al composites by using diamond grinding wheel in dry conditions. First and foremost, the grinding machined surface morphologies and chip shape were observed through scanning electron microscope (SEM) and the elements on chips were analyze through energy density spectrometry (EDS), and then the formation mechanism of different shape chips were analyzed. Experimental results indicated that chip shape was diversiform, including the Al-matrix chips, SiC particle chips, and Al-SiC mixed chips. Chunky chips are most common in the collected chips, together with saw-tooth chips, called Al-SiC mixed chips. According to the observation, the length of chunky chips was approximately 5–20 μm and the length of saw-tooth chips was about 10–20 μm. Cracks were formed in the cutting deformation zone and were grown in different ways because the high shear stress is the chip-forming mechanism of different shape chips.

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.

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/℃.

PCD tool performance in high-speed milling of high volume fraction SiCp/Al composites

This paper presents a systematical study on polycrystalline diamond (PCD) tool performance during high-speed milling of high volume fraction (65 %) and small size (nominal size 10 μm) SiC particle-reinforced aluminum, which is rarely reported before. The influence of milling parameters (milling speed and feed rate) and PCD particle size on tool wear were investigated. The results indicated that the tool wear increased dramatically with the milling speed, and it was not suitable to mill the material above 300 m/min for the industrial application. Larger feed rate could achieve larger removed volume before VC reached 0.6 mm, while the pattern reverses in terms of milling time. The optimized PCD particle size is 10 μm. The main wear modes of PCD tool were flank wear and crater wear, and the wear mechanism was analyzed by scanned electronical microscope (SEM), laser scanning microscope (LSM), and Raman spectroscopy.