Effect of Carbon Monoxide on the Sintering of SiC Whisker-Zirconia Composite

Reaction between silicon carbide and yttria-stabilized zirconia (YSZ) powders, ZrO2+3/2SiC=ZrC+3/2SiO(g)+1/2CO(g), was appreciable above 1400°C in argon atmospheres. The reaction was suppressed by adding an appropriate amount of carbon monoxide to the atmosphere. This finding was applied to the pressureless sintering of SiC whisker-YSZ composites. In CO (33%)-Ar atmosphere, 5vol% SiC whisker-YSZ composite densified to 97% theoretical density by pressureless sintering at 1550°C for 1h. At higher whisker contents, however, the sintered density of composite decreased with increasing whisker content in the same firing atmosphere, due to the formation of network structure by SiC whisker.