Silicon carbide low temperature sintering: the particle size effect of raw materials and sintering additive

Abstract

Aiming at dense sintering of silicon carbide ceramic, magnesium alloy powder was taken as additive, and silicon carbide powders with two different particle size were sintered by the same hot pressure sintering process. Result shows that ceramic sintered by the powder with larger particle size is denser. Magnesium and carbon segregation is observed in the sample prepared by powder with smaller particle size, in which silicon carbide particles cannot be uniformly dispersed by sintering additives. However, sintering additives distribute homogeneously among silicon carbide particles in the sample prepared by powder with larger particle size, which can effectively play a bonding role. In the selection of liquid phase sintering additives, particle size matching of raw material and sintering additives should be emphasized. Materials and methods Raw materialsSilicon carbide powders (purity >99%) with two different particle sizes were taken as raw materials and 8 wt% magnesium alloy powder as additive (Mg94.0 wt%, Al∼2.5 wt%-3.5 wt%). Average particle sizes of silicon carbide are 0.09 μm and 3.31 μm respectively, and average particle size of magnesium alloy is 86.30 μm.

Preparation of SiC coated graphite composite powders by nitriding combustion synthesis

“…3(a)), which facilitates the growth of SiC grains. In addition, sub-micron SiC grains with high sintering activity allow for much lower sintering temperatures and shorter soaking time to produce pore-free ceramics [52][53][54]. Therefore, the as-fabricated graphite@SiC particles could be easily densified to obtain the 3D continuous SiC skeletonreinforced graphite matrix composites with high mechanical and antioxidation properties.…”