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

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.