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

摘要： 为制备无明显变形且成本低、性能良好的片状氮化硅陶瓷,以α-Si₃N₄粉为原料,以LiAlO₂粉、Y₂O₃粉为烧结助剂,去离子水为溶剂,以四甲基氢氧化铵为分散剂,以亚克力树脂乳液为黏结剂,以水溶性低聚物为增塑剂,制备了固相体积分数为45%的氮化硅水基浆料。研究了分散剂加入量(质量分数为0.1%~0.9%,间隔0.1%)、球磨时间(1、3、5、7 h)、黏结剂加入量(质量分数2.5%、5.0%、7.5%)、增塑剂与黏结剂的质量比(0、0.3、0.6、0.9)等因素对浆料性能和流延效果的影响。结果发现,当分散剂、黏结剂的加入量(w)分别为0.6%、7.5%,增塑剂与黏结剂的质量比为0.6,低速球磨时间为5 h时,固相体积分数为45%的氮化硅水基浆料的流动性和流延效果最好。以此浆料进行流延、干燥、叠压,制得片状氮化硅陶瓷素坯,再在氮气气氛经 1 650 ℃常压烧结3 h,得到片状氮化硅陶瓷,其相对密度为97.12%,硬度为15.64 GPa,抗弯强度和断裂韧性分别为 583.58 MPa和6.72 MPa·m^1/2。

关键词: 氮化硅陶瓷, 固含量, 水基流延成型, 常压烧结