Research On Mouding And Sinter Of High-performance SiC Ceramic

Prepared silicon carbide slurry with low viscous and high solid loading was made by domestic submicron silicon carbide powder pre-treatment and surface modification.Then particle size distributions of the modified powders,the viscosity of slurry,and suspend stability was tested,it is confirmed that alkali cleaning can eliminate particle agglomeration efficiently is,prepared silicon carbide slurry of 50vol%solid loading and 300-450mPa·S viscosity with 0.1wt%car boxy methyl cellulose as dispersant,ammonia water adjusted pH to between 9.5-11,Tetra methyl ammonium hydroxide replacing ammonia water was added into CMC-silicon carbide slurry,and the viscosity decreased,TMAH-CMC is better at dispersing silicon carbide slurry.Silicon carbide green bodies by slip casting were pressure less sintered with Alumina - yttria as sintering additives,and the weight loss rate,density,hardness were determined and microstructure morphology has been analyzed.Studies have shown that the sintering temperature and sintering additives effected weight loss rate,relative density,hardness of materials.At 1950℃,adding 10wt%sintering additives,the relative density of silicon carbon ceramics reached 98.9%,and Vickers hardness 29.6GPa.Gel casting was also used to prepared silicon carbide ceramic to explore process parameters access to get high-strength green body.Linear shrinkage,bending strength of green body,relative density and bending strength of silicon carbide were tested etermined.The results showed that the process of vacuum degassing impact on the body. The formula containing 15wt%monomer,2.5wt%cross linking reagent,0.1wt% initiator could get the uniform green body with bending strength 28.3MPa.for the next available uniform body;when the sintering temperature to 2000℃,adding Alumina -yttria 10wt%,the ceramic density is to 89.1%,the bending strength to 238.6MPa.