SiC Fraction Research Articles

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.

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.

Principles of Technology and Mechanical Properties of Structural Ceramics Based on the Ternary System SiC–B4C–CrB2

ABSTRACTThe aim of this research was to work out the technology of ceramics for finding optimal sintering temperatures and to study their mechanical properties. Samples were prepared from powders with different volumetric ratio of the components. The powders underwent a prolonged co-milling in a vibratory mill, followed by uniaxial pressing, cold isostatic pressing (CIP) and pressureless sintering in a vacuum furnace under an argon atmosphere. Hot pressing (HP) was applied to some powder formulations. This study showed that it is advisable to carry out the first stage of the heat treatment up to 1550 ̊C under vacuum, with the aim of refining the grain surface from the oxygen-containing impurities due to their dissociation and evaporation. The studied area of formulations has a very narrow range of sintering (1940-1945 ̊C). It was established that the sinterability of the materials is affected by the amount of silicon carbide in the ternary system. Under pressureless sintering, the relative density of the material directly depended on the volume fraction of SiC. However, a change in the concentration of B4C had no appreciable effect on the sinterability of the materials. The application of HP helped us to reduce the negative impact of large amounts of SiC. Under HP at temperatures close to Teut, a certain decompaction of materials was observed with a significant amount of B4C (3-5% loss in density).

Microstructure and properties of electronic packaging shell with high silicon carbide aluminum-base composites by semi-solid thixoforming

The electronic packaging shell with high silicon carbide aluminum-base composites was prepared by semi-solid thixoforming technique. The flow characteristic of the SiC particulate was analyzed. The microstructures of different parts of the shell were observed by scanning electron microscopy and optical microscopy, and the thermophysical and mechanical properties of the shell were tested. The results show that there exists the segregation phenomenon between the SiC particulate and the liquid phase during thixoforming, the liquid phase flows from the shell, and the SiC particles accumulate at the bottom of the shell. The volume fraction of SiC decreases gradually from the bottom to the walls. Accordingly, the thermal conductivities of bottom center and walls are 178 and 164 W·m−1·K−1, the coefficients of thermal expansion (CTE) are 8.2×10−6 and 12.6×10−6 K−1, respectively. The flexural strength decreases slightly from 437 to 347 MPa. The microstructures and properties of the shell show gradient distribution.

Thermal behavior, electrical conductivity and microstructure of hot pressed Al2O3/SiC nanocomposites

Functional properties (e.g. thermal and electrical conductivity) of polycrystalline alumina ceramics can be modified by the addition of second phases, such as silicon carbide nanoparticles, carbon nanotubes or nanofibers, or graphene sheets. In this work we studied the influence of SiC particles addition on the DC electrical and thermal conductivity of the Al2O3/SiC micro/nanocomposites both at room and elevated temperatures. The composites with high relative density and with various volume fractions of SiC ranging from 3vol% to 20vol% were prepared by hot pressing at 1740°C and at 30MPa pressure in the atmosphere of argon. The influence of the volume fraction and the size of SiC particles (two different powders with the mean size of SiC particles 40 and 200nm were used), and final microstructure of the composites on thermal and electrical conductivity were evaluated. The properties of the composites were compared to the monolithic Al2O3 reference. The microstructure of the composites was significantly affected by the volume fraction of SiC, with the mean size of alumina matrix grains decreasing with increasing content of SiC particles. The maximum of room temperature thermal conductivity was measured in the composites with 20vol% of SiC (38W/mK), irrespective of the granulometry of the used SiC powder. The DC electrical conductivity increased with increasing volume fraction of SiC. The highest electrical conductivity 4.05×10−2S/m was measured in the composites containing 20vol% of SiC, in comparison to the electrical conductivity of the monolithic alumina reference, which was by four orders of magnitude lower. No statistically significant difference in thermal or electrical conductivity was found between the composited with different granulometry, but identical content of SiC.

Electrical properties of ZrB2–SiC ceramics with potential for heating element applications

ZrB2–10SiC, ZrB2–20SiC and ZrB2–30SiC ceramics were fabricated by hot pressing. The typical effects of volume fraction of SiC on the electrical properties were investigated. The electrical resistivities of as-prepared ZrB2–SiC ceramics increased as the volume fraction of SiC increased. The room temperature electrical resistivity values for ZrB2–10SiC, ZrB2–20SiC and ZrB2–30SiC ceramics were 6.54, 8.65 and 11.29μΩcm, respectively. ZrB2 acted as an electrical conductor and SiC acted as an electrical insulator in the ZrB2–SiC ceramics. The microstructure of ZrB2–SiC ceramics was also analyzed, which further proved the electrical resistivity measurement results.

A Study on Mechanical Properties of Aluminium Alloy (Lm6) Reinforced With Fly Ash, Redmud and Silicon Carbide

This work deals with fabricating or producing aluminium based metal matrix composite and thenstudying its microstructure and mechanical properties such as tensile strength, impact strength and wear behavior of produced test specimen. In this present study a modest attempt has been made to develop aluminium based MMCs with reinforcing material with an objective to develop a conventional low cast method of producing MMCs and to obtain homogeneous dispersion of reinforced material. To achieve this objective stir casting technique has been adopted. Aluminium Alloy (LM6) and Sic, Fly Ash, Red mud has been chosen as matrix and reinforcing material respectively. Experiment has been conducted by varying weight fraction of Sic, Fly Ash, Redmud. The result shown that the increase in addition of Fly Ash is giving better result when compared with Redmud.

Mesoscopic Model for SiC<sub>P</sub>/Al Composites and Simulation on the Cutting Process

For deep application of the FEM on the study of cutting mechanism of SiCP/Al, the article completed the algorithm to generate the mesoscopic model of SiCP/Al with the parameterization of the shape and volume fraction of SiC based on the ABAQUS scripting language python. Two-dimensional randomly distributed circular particles model, circular mixed with regular polygon particles model and arbitrary polygon model are generated with volume fraction of 30% and cutting simulations were carried out on the models. Results show that cutting force of SiCP/Al with uniform distribution and size of circular particles will be relatively stable and during the cutting process, stress field changes with the shape and distribution of the particles and the relative position of the particles and tool. Poor surface quality was mainly caused by the interaction among the tool, the particles and the matrix material.

Synthesis of Al- Sic Composite Prepared By Mechanical Alloying

Aluminium matrix composites (AMCs) refer to the class of light weighthigh performance aluminium centric material systems. Properties of AMCs can bepersonalized to the demands of special industrial applications by appropriate combinationsof matrix, reinforcement and processing technique. The widespread acceptance of particulate metal matrixcomposites for engineering applications has been hindered by the high cost of producingcomponents. Although several technical challenges exist with casting technology yet it can beused to overcome this problem. Achieving a uniform distribution of reinforcement within thematrix is one such challenge, which affects directly on the properties and quality of compositematerial. In the present reading a modest effort has been made to develop aluminium basedsilicon carbide particulate MMCs with an objective to develop a conventional low cost technique ofproducing MMCs and to obtain homogenous dispersion of ceramic material. To achieve theseobjectives Mechanical alloying method of powder metallurgy has been adopted and consequentproperty analysis has been made. Experiments have been conducted by varyingweight fraction of SiC (4%, 6%, 8% and10%), while keeping all other parametersconstant. Friction and wear characteristics of Al-SiC composites have been investigated under dry sliding conditions. Dry sliding wear tests have been carried out using pin-on-disk wear test rate normal loads of 10, 20, 30, 40 and 50N and at constant sliding velocity of 1.6m/s. The results show that the 'developed method' is moderately successful to attain uniformdispersion of reinforcement in the matrix. An increasing trend of hardness with increase in weight percentage of SiC has been observed. It was found from the testing that the wear rate decreases linearly with increasing weight fraction of silicon carbide.

Study of Cutting force and Surface Roughness in machining of Al alloy Hybrid Composite and Optimized using Response Surface Methodology

Metal matrix composites, in particular, Aluminium Hybrid Composites are gaining increasing attention for applications in air and land because of their superior strength to weight ratio, density and high temperature resistance. This paper presents the results of experimental investigation on machinability properties of Silicon Carbide and Boron Carbide reinforced Aluminium 356 hybrid metal matrix composite. The composites were prepared by varying weight fraction of SiC (5%, 10%, 15%) and keeping the Boron Carbide weight fraction (5%) is constant using modified stir casting technique. Four layer coated carbide insert (TiN. Al2O3, TICN, TiN) designated as CNMG 120408 FR was used to machine the fabricated composites. Face centered central composite experimental design coupled with Response Surface Methodology (RSM) was used for modeling that the process output characteristics that influence by weight fraction, speed, feed rate, cutting depth. The experimental results imply that surface Roughness criteria are found to increase with increase of feed. At 0.206.mm/rev feed, the Surface Roughness deteriorated rapidly. Roughness decreases at higher cutting speed during machining. With the help of Mintab software, RSM showed an accuracy of 95%. Moreover, a good agreement was observed between the experimental and the predicted values of surface roughness and cutting force. Optimal cutting condition which leading to the minimum surface roughness and cutting force were highlighted.

Investigation on the Cutting Force of High-Speed Milling of High Volume Fraction of SiC<sub>p</sub>/Al Composites with PCD Tools

High-speed milling tests for 65vol.%SiCp/6063Al composites were performed by polycrystalline diamond (PCD) tools, response surface methodology was utilized in this study, and a cutting force model was developed through response surface methodology, which contained some important parameters such as cutting speed, cutting feed rate, cutting depth and cutting width. The analysis of variance (ANOVA) indicated that the proposed mathematical model can adequately describe the relationship between cutting force and cutting process parameters. The results show that cutting depth is the biggest important factor of milling force, and cutting feed rate is the second important factor, cutting speed is the third; milling force would not increase with the increasing of cutting width.

Effects of high pressure and SiC content on microstructure and precipitation kinetics of Al–20Si alloy

Abstract The microstructure and the precipitation kinetics of Si in Al–20Si composites reinforced with different amounts of SiC particles are investigated as a function of the solidification pressure. The results show that the formation of primary silicon is hindered and a supersaturated dendritic α-Al phase is formed with increasing pressure. In addition, the morphology of the eutectic silicon changes from coarse acicular to short lamellar shape. After the addition of the SiC particles, the morphology of primary Si transforms from coarse polygonal to fine blocky shape, the size decreases from 72.5 μm to 11.2 μm at 1 GPa, and the eutectic Si varies from lamellar to fine fibrous structure at 3 GPa. The peak temperature and the activation energy for the Si precipitation decrease with increasing of the solidification pressure and the volume fraction of SiC. More precipitates with smaller size can be observed for high SiC contents.

Effect of SiC volume fraction and size on dry sliding wear of Fe/SiC/graphite hybrid composites for high sliding speed applications

In this work we investigated the friction and wear properties of Fe/SiC/graphite hybrid composites using a sub-scale dynamometer disk brake testing system. Two particle size ranges (1–30μm and 150–180μm) and three particle volume fractions (10%, 15% and 20%) of SiC were considered. The sliding speed conditions considered in this study (25–35m/s) were comparable to that experienced by brake materials in high speed braking applications in aircrafts, race car and high speed trains. We examined the effect of coating the SiC particles with BaSO4 to improve interfacial properties and prevent potential undesirable interfacial reactions. The wear loss was found to decrease with increasing volume fraction of SiC for all particulate sizes. At low sliding speeds the composites with large particle sizes and high volume fractions were found to be more effective in controlling wear. On the other hand, at higher sliding speeds the high volume fraction composites were found to be more effective in controlling wear for all particle sizes. This is attributed to a transition in the wear mechanism at higher sliding speeds.

Use of dispersants to enhance incorporation rate of nano-particles into electrodeposited films

Abstract The effect of a cationic dispersant, polyethyleneimine (PEI) on the co-deposition of 45–55 nm and 1.0 μm SiC particles with Ni on a rotating disk electrode is investigated. Addition of 500 ppm of PEI into a Watts bath increases the SiC fraction in the nano-composites without affecting the electrodeposition kinetics, however films have undesired properties, as evidenced by cracks. A pre-coating procedure, in which nano-particles are treated with 500 ppm PEI prior to introduction into the plating bath is described. The pre-coating method increases the SiC incorporation to values as high as 23 vol%, one of the highest reported values for nano-particles in electrodeposited films, without decreasing the current efficiency. In addition, the pre-coating method facilitates bath-composition optimization when, for example, leveling agents are employed; otherwise the leveling agent and PEI competitively adsorb onto the SiC particles. The efficacy of employing the pre-coating procedure in manufacturing, where plating baths need a long life, may be satisfactory. Strategies where dispersants are first attached to ceramic particles prior to integration into a plating bath containing other additives may lead to high volume fractions of particles thus harder deposits. The detailed procedures to achieve high-volume fractions required modification when transitioning from micron- to nano-sized particles.

Fabrication and mechanical properties of SiC reinforced reaction-bonded silicon nitride based ceramics

SiC reinforced Si3N4 based ceramics were fabricated via nitridation of silicon, and the influence of SiC addition on the microstructure and mechanical properties of the as-prepared Si3N4/SiC ceramics were investigated. With SiC addition increase, β-Si3N4 grains growth was inhibited and equiaxed Si3N4 grains increased. This can be attributed to grain-boundary pinning effect due to SiC dispersion, resulting in finer β-Si3N4 grains with high aspect ratio. After nitridation and post-sintering at 1750°C for 2h, Si3N4/SiC composites with flexural strength of 614MPa, young's modulus of 263GPa, hardness of 14.3GPa were obtained with 10wt% SiC addition. Compared with pure Si3N4 ceramics, the fracture toughen ss was also improved, reaching the peak value of 3.45MPam1/2 at the SiC fraction of 10wt%. This can be accounted for the phenomena of crack deflection and bridging.

A THERMO-DAMAGE STRENGTH MODEL FOR THE SiC-DEPLETED LAYER OF ULTRA-HIGH-TEMPERATURE CERAMICS ON HIGH TEMPERATURE OXIDATION

At high temperatures above 1650°C, the SiC -depleted layer of ultra-high-temperature ceramics which has high porosity appears during the oxidation process. In this present paper, based on the studies of the oxidative mechanisms and the fracture mechanisms of ultra-high-temperature ceramics under normal and high temperatures, a thermo-damage strength model for the SiC -depleted layer on high temperature oxidation was proposed. Using the model, the phase transformation, microstructure development and fracture performance in the SiC -depleted layer on high temperature oxidation were studied in detail. The study showed that the porosity is mainly related to the oxidation of SiC . And while the SiC is substantially completely oxidized, only a very small part of matrix is oxidized. The fracture strength of the SiC -depleted layer degrades seriously during the high temperature oxidation process. And the bigger the initial volume fraction of SiC , the lower the fracture strength of the SiC -depleted layer is. This layer may become the origin of failure of material, thus the further researches should be undertaken to improve the oxidation behavior for the ultra-high-temperature ceramics in a wider temperature range.

Sliding wear of LM25 aluminium alloy with 7.5% SiC+2.5% TiO2 and 2.5% SiC+7.5% TiO2 hybrid composites

An experimental investigation on the wear behavior of aluminium alloy LM 25 and its composites reinforced with 7.5% SiC + 2.5% TiO2 and 2.5% SiC + 7.5% TiO2 is carried out to ascertain which constituent is having more influence on the metal matrix composites. The hybrid composite material is prepared by stir casting process. The wear and frictional properties of hybrid metal matrix composite are studied by performing dry sliding wear test using a pin on disc wear tester. The experiments are conducted at a constant sliding velocity of 1.04 m/s and a sliding distance of 628 m over various loads of 3, 4 and 5 kg. The result shows that, the reinforcement SiC and TiO2 has improved the wear resisting property of LM 25 alloy composite. The results also indicate that the three-fourth volume fraction of the TiO2 in a 10% volume fraction of reinforcement has better wear and frictional property than the three-fourth volume fraction of SiC. The coefficient of friction decreases with the increasing load and particle reinforcement. The microstructure analysis reveals that SiC and TiO2 particulate are uniformly distributed in the matrix. The wear surfaces are examined by scanning electron microscope which indicates an abrasive wear mechanism due to hard ceramic particles exposed on the worn surface.

MICROSTRUCTURE AND PROPERTIES OF SiC PARTICLES REINFORCED COPPER BASED ALLOY COMPOSITE

Copper-matrix composites reinforced with SiC particles are prepared by mechanical alloying. The microstructure characteristics, relative density, hardness, tensile strength, electrical conductivity, thermal conductivity and wear properties of the composites are investigated in this paper. The results indicate that the relative density, macro-hardness and mechanical properties of composites are improved by modifying the surface of SiC particles with Cu and Ni . The electrical conductivity and thermal conductivity of composites, however, are not obviously improved. For a given volume fraction of SiC , the Cu / SiC ( Ni ) has higher mechanical properties than Cu / SiC ( Cu ). The wear resistance of the composites are improved by the addition of SiC . The composites with optimized interface have lower wear rate.

Effect of the volume fraction of SiC on the microstructure and creep behavior of hot pressed Al2O3/SiC composites

Al2O3/SiC composites containing different volume fractions (3, 5, 10, 15, and 20 vol%) of SiC particles have been fabricated by mixing alumina and silicon carbide powders, followed by hot pressing at the temperature 1740 °C for 1 h under the pressure of 30 MPa and in the atmosphere of Ar. The effect of the volume fraction of SiC on the microstructure and creep behavior of the composites was investigated and possible creep mechanisms were discussed. The creep behavior of the composites at temperatures up to 1350 °C, and mechanical load up to 200 MPa, i.e. under conditions which were more severe than those reported previously, was studied, and compared to the monolithic Al2O3 reference. The microstructure and creep behavior of the Al2O3/SiC microcomposites was significantly influenced by the volume fraction of SiC particles and the average size of the alumina matrix grains. When compared to monolithic Al2O3, the creep resistance of the Al2O3/SiC composites was markedly improved, especially in the materials with 10 vol% of SiC. Long loading time before mechanical failure suggested grain boundary sliding and cavitation controlled creep behavior. The enhanced creep resistance was attributed to grain boundary pinning by the intergranular SiC nanoparticles.

Research the Preparation of SiC/Al Composites by High Energy Ball Milling

High energy ball milling was used to preparation SiC/Al composites flakes. The research found the milling parameter of high energy milling was the ball/powder ration is 20:1, the rotary speed is 800 r/min, the milling time is 100min.Also researched the molding process of SiC/Al composites, the change of grain size and the weight fraction of the SiC, The research also found the mechanical properties of SiC/Al composites affected by the molding process. It was found that to reduce particle size and increasing of weight fraction of SiC, tensile strength of the SiC/Al composites increased. When the weight fraction of SiC in the SiC/Al composites is about 16%, the mechanical properties of SiC/Al composites about the hardness and tensile strength also get the high-point, the hardness and tensile strength is about 95HB and 248MPa.