Patent attributes
A SiAlON ceramic body made from a starting powder mixture that includes silicon nitride powder and one or more powders that provide aluminum, oxygen, nitrogen, and two selected rare earth elements to the SiAlON ceramic body wherein the selected rare earth elements are selected from at least two groups of the following three groups of rare earth elements wherein Group I comprises La, Ce, Pr, Nd, Pm, Sm and Eu, and Group II comprises Gd, Tb, Dy and Ho, and Group III comprises Er, Tm, Yb and Lu. The SiAlON ceramic body includes a two phase composite that includes an alpha prime SiAlON phase and a beta prime SiAlON phase wherein the alpha prime SiAlON phase contains one or more of the selected rare earth elements excluding La and Ce. The silicon nitride powder makes up at least about 70 weight percent of the starting powder mixture wherein the beta-silicon nitride content of the silicon nitride powder has a lower limit equal to zero weight percent and an upper limit equal to about 1.6 weight percent of the silicon nitride powder.
