低温烧结制备高气体渗透率的多孔碳化硅陶瓷研究

Preparation of Porous Silicon Carbide Ceramics with High Gas Permeability by Low-temperature Sintering

采用低温烧结法制备多孔碳化硅陶瓷,研究了成型压力、烧结温度等对其开气孔率、抗压强度、表面最大孔径和气体渗透率等的影响,通过SEM、EDS等表征其微观形貌和成分等。结果表明：在较低烧结温度850～950℃中烧成时,随着烧成温度的升高,多孔碳化硅陶瓷开气孔率和气体渗透率先增大后减小,体密度先减小后增大,表面最大孔径增加;抗压强度随开气孔率的增大而降低,压缩应力-应变表明多孔陶瓷的压溃分阶逐次进行,通过数次的局部压溃现象（应力台阶）来松弛主裂纹尖端的应力集中;随着成型压力的增加,其最大孔径和气体渗透率减小;在50 MPa成型870℃烧成时,多孔碳化硅陶瓷开气孔率达到38.4%,抗压强度80 MPa,表面最大孔径为12.86μm,气体渗透率达361.82m^3/（m^2·h·k Pa）。

The effect of forming pressure and sintering temperature of porous silicon carbide（SiC） ceramics prepare dat low temperature on open porosity、compressive strength、maximum pore size in surface and gas permeability was studied, and microstructure and composition of specimen were characterized by SEM and EDS. The results show that when porous SiC was sintered at 850 ～ 950 ℃ in air atmosphere,as sintering temperature increased, open porosity and gas permeability of porous SiC ceramics firstly improved and then decreased, but density decreased and then increased, maximum pore size increased all along; with the increase of open porosity, compressive strength decreased, compressive stress-strain curve indicated the crushing of porous SiC ceramics occurredin order successive through several partial crushing（stress decrease） to relax the stress concentration of main crack tip; with the increase of forming pressure, the maximum pore size and gas permeability decreased; the optimized porous SiC ceramics withopen porosity 38.4%, compressive strength 80 MPa, maximum pore size 12.86 μm, gas permeability 361.82m^3/（m^2·h·k Pa） could be prepared by 50 MPa forming pressure and 870 ℃ sintering temperature.