無収縮アルミナ材料

抄録

To fabricate a sintered Al₂O₃ with high dimensional accuracy by near-net-shape firing, oxidation and sintering behavior of compacts of a mixture of Al₂O₃ and Al powders was studied. The compacts were prepared by compressing green-sheets obtained by doctor-brade method at 196MPa and fired at 1600°C or less in air. The oxidation of Al in the compact occured between about 450°C and 1300°C, and prevents the compact from shrinking in firing process at 1300°C or less. A part of melting Al in the compact spilled out of the compact in firing process, because Al melts below 800°C, its oxidation temperature. MgO, CaCO₃ and TiO₂ powders were added to prevent the Al spillage and Si powder was added to prevent the shrinkage by sintering at 1400°C or more. As a result, the sinterd Al₂O₃ having a density of 3.72g/cm³ and 0.7% shrinkage by sintering was fabricated by sintering with oxidation of Al and formation of mullite.