摘要 |
In producing beta / beta '' alumina, finely divided zirconia (typically 0.1 to 3% by weight) is included in the precursor materials before sintering whereby, during subsequent sintering, any calcia present as an impurity is dissolved in the zirconia forming stabilised cubic or tetragonal phase zirconia as a discrete phase in the beta / beta '' alumina matrix. By this technique, the effect of calcium impurities on the ratio of beta '' to beta can be reduced or eliminated. |