초록

A ceramic having a relatively high proportion of an alpha prime SiAlON phase and exhibiting high hardness and toughness. In a particularly preferred embodiment, a cation of Gd is used as a modifying cation.

대표청구항 ▼

[ What is claimed is:] [27.] A method for making a ceramic article, the method comprising:(a) providing an alpha silicon nitride starting material in a major amount of the overall starting materials;(b) densifying said starting material to form a ceramic body having:(i) a first phase present in an a

[ What is claimed is:] [27.] A method for making a ceramic article, the method comprising:(a) providing an alpha silicon nitride starting material in a major amount of the overall starting materials;(b) densifying said starting material to form a ceramic body having:(i) a first phase present in an amount of at least about 45% by weight of said material, including a plurality of alpha prime SiAlON elongated grains having a majority of said grains present with an average grain diameter of at least about 0.5 microns and an aspect ratio greater than about 6:1;(ii) a second phase including a phase selected form the group consisting of glass phase, beta SiAlON, AlN polytypoids, melilite, garnet and mixtures thereof;said alpha prime SiAlON grains having the formula R.sub.m/3 Si.sub.12-(m+n) Al.sub.(m+n) O.sub.n N.sub.16-n, with m ranging from about 0.9 to about 3.2 and with n ranging from about 0.4 to about 1.8, and where R is a cation of an element selected from the group consisting of Nd, Sm, Gd, Dy, Yb, Y, and mixtures thereof.