关键词: 氮化硅陶瓷, 固含量, 水基流延成型, 常压烧结

Abstract: To prepare plate-like silicon nitride ceramics with minimal deformation,low cost,and excellent performance,a water based silicon nitride slurry with a solid loading of 45 vol% was prepared using α-Si₃N₄ powder as the raw material,LiAlO₂ powder and Y₂O₃ powder as the sintering aids,deionized water as the solvent,tetramethyl ammonium hydroxide as the dispersant,acrylic resin emulsion as the binder,and water-soluble oligomer as the plasticizer.The influence of factors such as the dispersant addition (0.1%-0.9%,at an interval of 0.1%,by mass),ball milling time (1,3,5 and 7 h),binder addition (2.5%,5.0% and 7.5%,by mass),and mass ratio of plasticizer to binder (0,0.3,0.6 and 0.9) on the properties and tape casting effect of the slurry was studied.The results show that with the dispersant addition of 0.6%,the binder addition of 7.5%,the mass ratio of plasticizer to binder of 0.6 and the low speed ball milling time of 5 h,the water based silicon nitride slurry with a solid loading of 45% performs the best flowability and tape casting effect.Using this slurry for tape casting,drying,and laminating,plate-like silicon nitride ceramic green bodies were obtained.Then,they were pressureless sintered at 1 650 ℃ for 3 h in a nitrogen atmosphere to obtain plate-like silicon nitride ceramics.The ceramics have the relative density of 97.12%,hardness of 15.64 GPa,bending strength of 583.58 MPa and fracture toughness of 6.72 MPa·m^1/2.

Key words: silicon nitride ceramics, solid loading, water based tape casting, pressureless sintering