2020 Volume 92 Issue 9 Pages 469-476
The two-step reaction sintering method was applied to fabricate SiC ceramics to improve wear resistance using feedstocks of Si, C, and SiC powder, where the powder size of SiC was changed in the wide range from 5 to 150 μm. Various powders were prepared as starting materials by mixing SiC powder of different sizes. The melt infiltration method was also employed using Si and Fe-Si alloy. This study investigated effects of the SiC powder size on the structure and wear properties of sintered SiC ceramics. The microstructure was observed using a laser microscope. Wear properties were evaluated using abrasive and erosive wear tests.
All sintered samples exhibited a constant area fraction of SiC of about 65%, irrespective of the SiC grain size. The SiC grain size only slightly affected the abrasive wear rate, suggesting that the wear rate was not governed by the SiC grain size, but rather by the area fraction of SiC. The erosive wear rate was influenced strongly by the SiC grain size, i. e., the intergranular distance. The wear rate decreased markedly as the SiC grain became finer. The most favorable abrasive and erosive wear rates using steel shots were about 2.2 × 10-6 mm3/Nm in all samples and 0.1 mm3/kg at intergranular distance of the SiC less than 20 μm. Consequently, sintered SiC ceramics with superior wear resistance were obtained using a finer SiC powder feedstock.
