A Study On The Bending Strength And Wear Resistance Of SiC/Al Composites By Pressureless Infiltration

SiC preforms were fabricated by adding pore-forming materials (starch). And using pressureless infiltration technique, SiC/Al composites were made. The influence of several factors, such as size of particles, contents of starch and grade of particles, on the porosity of preforms was investigated. The effects of these factors on the bending strength are also systematically studied. And the behavior of friction and wear of SiC/Al composites is preliminarily investigated. Furthermore, by the analyses of microstructures, the fracture and worn surfaces, the mechanism of fracture and wear of SiC/Al composites are discussed.The results have shown that a suitable pressure is elementary of fabricating the preforms with a homogenous microstructure and good property. Content of pore-forming materials and particles matching are two major factors, influencing on the porosity of SiC preforms. The porosity of preforms increased with the increase of starch contents. Particle matching is an effective way to reduce porosity, and obtain the preforms with high volume fraction of SiC. Matching particles also reduces the porosity of composites. Temperature is very important to fabricate SiC/Al composites by pressureless infiltration. And a suitable holding time is elementary to get the composites with good mechanical property.The distribution, size and volume fraction of SiC particles, porosity are the factors influencing on the bending strength of SiC/Al composites. The bending strength is increased with the decrease of size of particles. Fine particles are homogenously distributed in Al matrix, and make the movement of dislocation hard, so the Al matrix is reinforced. At the same time, the small distance between particles increases the force to wind second-phase particles for the dislocation, so the bending strength of the composites increased. The phenomena of SiC particles lap each other is decreased with increase of the volume fraction of Al phase in composites. As the result, the bearing area is increased effectively and the bending strength of SiC/Al composites is...