Al//2O//3-ZrO//2 CERAMICS PREPARED FROM CVD POWDERS.

The densification and tetragonal (t)-ZrO//2 content of sintered Al//2O//3-ZrO//2 ceramics were studied by starting from CVD ZrO//2 powder mixed with various Al//2O//3 powders, including CVD Al//2O//3, or from CV codeposited Al//2O//3-ZrO//2 powder. Strong dependence of t-ZrO//2 content on sintering temperature and on weight percent ZrO//2 in Al//2O//3-ZrO//2 ceramics suggested the importance of the ZrO//2 dispersion and grain-growth control for achieving higher t-ZrO//2 content. Comparisons of t-ZrO//2 contents measured on sintered and fractured surfaces indicated that the transformation-zone thicknesses on fracture were very large (4. 5-7. 8 mu m) with specimens prepared from CVD Al//2O//3 plus CVD ZrO//2 or from CV codeposited Al//2O//3-ZrO//2 probably due to extensive microcrack formation.