| 摘要 |
<p>An alumina ceramic article and a method for preparing the article. The method has the steps of: (1) Compacting a mixture of a first concentration of particulate aluminum oxide and a second concentration of particulate zirconium oxide alloy. The first concentration is greater than 50 weight percent of the total of the first and second concentrations. The first concentration is sufficient to prevent retention of the zirconium oxide alloy particles in the surface in a predominantly tetragonal crystal structure. The zirconium oxide alloy is zirconium oxide and a secondary oxide selected from the group consisting of MgO, CaO, Y2O3, Sc2O3, and rare earth oxides. The zirconium oxide alloy has a concentration of secondary oxide of 2 to 20 mole percent relative to the total of the zirconium oxide alloy. The compacting results in the formation of a shaped intermediate product. (2) Subsequent to formation of the shaped intermediate product, providing contact between the shaped intermediate product and a dopant oxide selected from MgO, ZnO, FeO, CoO, NiO, and MnO. (3) Sintering the shaped intermediate product in contact with the dopant oxide. During the sintering the dopant oxide diffuses into the surface of the shaped intermediate product, converting the aluminum oxide particles in the surface into cubic spinel and converting the zirconium oxide alloy particles in the surface from a tetragonal crystal structure to cubic and monoclinic crystal structures. The core is sintered particles of aluminum oxide or of aluminum oxide and zirconium oxide alloy in a tetragonal crystal structure. The surface or case is sintered particles of cubic spinel or cubic spinel and zirconium oxide alloy in non-tetragonal crystal structures. <IMAGE></p> |
