烧结温度对PVT制备定向多孔碳化硅陶瓷组织和性能的影响

For the directional SiC porous ceramics obtained by the high-temperature recrystallization process, effects of firing temperature on the microstructure and mechanical properties were investigated. The results showed that the porous SiC ceramics porous ceramics obtained was the approximate isotropic homogeneous porous structure when the firing temperature was below 2050 ℃,. When the temperature exceeded 2150 ℃, the formation of orientation of porous silicon carbide began, and as the temperature increased, the weight loss increased, and the axial bending strength became higher than the radial value, which was slightly increased followed by decrease. With condition of an Ar atmosphere of 0.3-0.5 × 105Pa, the sintering temperature of 2300 ℃ and soaking time of 2 hours, the loosely packed silicon carbide samples were sintered and oriented porous silicon carbide ceramics with axially aligned pore and grain were obtained. The porosity reached to 63.2%, and the ratio of axial and radial strength was 5.34-5.69.