配料Z值对常压烧结Sialon结构与性能的影响

Effect of the value of feeding Z on the construction and properties of pressureless sintered Sialon ceramics

由于Si6-ZAlZOZN8-Z(Z值变化范围为 0～ 4.2 )制备过程中物理、化学反应十分复杂 ,同时几乎没有可能制备单晶全致密Sialon材料 ,从而使Z值的精确控制十分困难 .然而 ,大量研究表明 ,Z值对材料的结构和性能 ,如晶格常数、密度、硬度、断裂韧性、强度等有重要的影响 .用Si3 N4 ,Al2 O3 ,AlN ,Y2 O3 混合料以聚乙烯醇 (PVA)为成型剂 ,用模压法成型 ,单位压制压力为 78.5MPa,烧结在石墨电阻炉中进行 ,以Si3 N4 +Al2 O3 +AlN +BN混合粉为烧结填料 ,工业氮气为保护气氛 ,制得了相对密度大于 99% ,抗弯强度为 6 12 .2MPa的Sialon陶瓷 .结果表明 :在一定实验条件下 ,Z为 1和 2的材料烧结致密化程度最好 ,强度随烧结坯密度增加呈指数增加 ,要获得高的强度 ,材料密度不能低于 3.2g/cm3 ;晶格常数a随Z值增加呈线性增加 ,c值随Z变化规律不明显 ;Z值为 1～

The general stoichiometrical composition of β′ Sialon is Si 6- Z Al Z O Z N 8- Z . Z changes from 0 to 4.2. The fabrication of Sialon involves complex physical and chemical reactions, so crystallized full density Sialon matericals can hardly be formated, and the value of Z is difficult to adjust precisely. The value of Z is a fundamental factor which decides the construction and main properties of pressureless sintered Sialon ceramics, such as lattice parameter, density, hardness, toughness, bending strength, et al . A Sialon ceramics with the relative density more than 99% and bending strength up to 612.2 MPa was prepared by pressureless sintering of the powder mixture of Si 3N 4, Al 2O 3, AlN and Y 2O 3. It was discovered that the Sialon prepared by the feeding value of Z =1, 2 had higher densification, and the bending strength increased exponentially with densities increasing. It was also discovered that lattice parameters ( a ) increased with Z value increasing.