| 摘要 |
PURPOSE:To provide the subject insulator which is low in sintering temp., is less deformed, is inexpensive and has excellent mass productivity by compounding fine particles of alumina as an essential component and specific 3 kinds of oxides as an auxiliary component at prescribed ratios and calcining and sintering the mixture. CONSTITUTION:(A) 85-97.5wt.% fine particles of the alumina as the essential component and the auxiliary component consisting of (B) 0.5-15wt.% >=1 kinds selected from SiO2, MgO, CaO, BaO, ZnO, and SrO, (C) 0.55-9wt.% B2O3, and (D) 0.3-6wt.% >=1 kinds selected from TiO2, HfO2, ZrO2, NiO, Cr2O3, CaF2, and As2O3 are compounded. The resulted powder raw material is then molded and the molding is calcined and sintered, by which the high-alumina insulator for an ignition plug is produced. The glassy material formed in the initial calcination stage is thereby phase-split to increase the high-temp. viscosity and to restrain the movement of the sintered particles of the alumina; therefore, the generation of bending, warpage, etc., in the calcination is suppressed. |
