STABILISED ZIRCONIA AND A PROCESS FOR THE PREPARATION THEREOF
1342406 Zirconia refractory MAGNESIUM ELEKTRON Ltd 28 June 1972 [29 June 1971] 30399/71 Heading C1J A stabilized zirconia body is made by mixing zirconia and a yttria concentrate containing 35 to 70% yttria and the remainder rare earth metal oxides, and having been prepared from a naturally occurring mineral containing yttrium and rare earth metals without isolation of pure yttria, the concentrate being present in an amount to provide at least 3 mol. per cent of yttria plus heavy rare earth (Atomic Nos. 62-71) oxides. The mixture is then calcined from 1 to 10 hours at 900 to 1500 C. The yttria concentrate is preferably dissolved in HCl and added to an aqueous slurry of basic zirconia sulphate, alkali added and the resulting hydroxides washed, dired and calcined. In the examples the following rare earths were present in addition to yttria: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Th.