关键词: 反应烧结SiC, TiN, 注浆成型, 力学性能

Abstract: When preparing reaction-bonded SiC ceramics by slip casting,due to the introduction of a large amount of solvent,problems of high porosity and low strength exist for the products after subsequent drying,vacuum Si infiltration,and sintering.To enhance the mechanical properties of reaction-bonded SiC ceramics prepared by slip casting,fine SiC powder,carbon black,and graphite were used as main starting materials,sodium carboxymethyl cellulose as the binder,polyvinylpyrrolidone as the dispersant,and TiN powder as the additive to prepare SiC ceramic slurries with TiN extra-addition of 0,2.5%,5%,and 7.5%,by mass.SiC ceramics were obtained after slip casting and heat treatment at 1 740 ℃ for 2 h in the Si embedded condition.The effect of the TiN addition on the physical properties,phase composition,and microstructure of the reaction-bonded SiC ceramics was investigated.The results show that when the TiN addition increases from 0 to to 7.5%,the apparent porosity shows a slight downward trend,while the bulk density increases accordingly;TiN can react with free Si to generate TiSi₂ with high fracture toughness,and to some extent consume the free Si in the sample,improving the mechanical properties of the reaction-sintered SiC ceramics.Therefore,when the TiN addition increases from 0 to 7.5%,the modulus of rupture increases from 204.8 MPa to 304.3 MPa,an increase of 48.6%,and the fracture toughness also increases from 3.76 MPa·m^1/2 to 4.42 MPa·m^1/2,with a growth rate of 17.6%.When the TiN powder addition is 7.5%,the reaction-sintered SiC sample exhibits the optimal comprehensive performance.

Key words: reaction-sintered SiC, TiN, slip casting, mechanical properties