| 摘要 |
PROBLEM TO BE SOLVED: To stably obtain a magnesia-added β-alumina having high electric conductivity and high strength by mixing an aluminum starting raw material and a sodium starting raw material and calcining the mixture to prepare a calcined powder of β-alumina and after that, adding a magnesia starting raw material, pulverizing, mixing, and sintering after forming. SOLUTION: The calcined powder having high β"-conversion ratio is obtained by mixing the aluminum starting raw material such as aluminum oxide and the sodium starting raw material such as sodium carbonate in the molar ratio of 5-7 expressed in term of Al2 O3 /Na2 O and drying and pulverizing at need, and then calcining at 1,200-1,350 deg.C. Next, 1.5-4.5 pts.wt. magnesium starting raw material is added into 100 pts.wt. calcined powder and mixed, pulverized and then, formed into a prescribed shape, sintered at 1,540-1,650 deg.C to obtain the β-alumina sintered compact. By controlling the molar ratio of Al2 O3 /Na2 O to 5.8-6.9 and MgO content to 2-3 wt.% after sintering, 93-99% β"-conversion ratio is attained using a high purity raw material. |
