Effect Of Particle Shaping On Mechanical Properties Of High Volume SiC_p/Al Composites

In this paper,a variety of domestic market abrasive grade SiC particles are selected,and modificated by fluidized bed jet mill several times.Three kinds of shape parameters of as-received and modificated particles were measured to characterize and evaluate the modification effect.High volume fraction SiCp/Al composites were prepared by pressureless infiltration,using of as-received and modificated SiC particles as reinforcement respectively,and its mechanical properties were studied experimentally by 3-point bending test.The influence of particle aspect ratio and volume fraction on the elastic modulus of composites was investigated based on Halpin-Tsai equation.The stress and strain distributions of composite materials around as-received and modificated particles under bending load were simulated and compared by using ABAQUS software.It was estimated that the particle size of the 4 groups was reduced after the modification treatment compared with that of the as-received particles,with an amplitude of 10%?20%.After modification,the aspect ratio decreases,and the silhouette coefficient and roundness were closer to 1,which was,the shape of particles was closer to the sphere.Through finite element simulation,it is found that when the particles have sharp corners,the concentration is easy to occur at the sharp corners.The stress concentration area in the composite is much smaller than that of the original composites.Through local simulation tests,it was found that the strength at the sharp corners of the particles has reached or exceeded the breaking strength of the material in the case where the overall load is not high.By analyzing the results of the three-point bending test data,the analysis concludes that high volume fraction aluminium matrix composites were prepared by using modificated particles as reinforcement,and the flexural strength and elastic modulus of the 4 groups of composites increased by 10%?15%compared with those without modification.Modification inhibited the stress concentration around the particles and further improved the strength of the composites,and it also increased the bulk density of SiC particles and their volume fraction in the composites,thus improving the elastic modulus of the composites.The fracture analysis showed that many of the particles in the as-received particle composite have been broken at some of its sharp edges and corners,and this situation has been improved well after plastic shaping.