Improvement in the Low-Temperature Sintering Performance and Characteristics of Alumina with CuO-TiO₂-Nb₂O₅ Additive by Controlling the Firing Atmosphere

Abstract

For the purpose of lowering the sintering temperature of alumina with a CuO-TiO₂-Nb₂O₅ additive, effects induced by changes in the firing atmosphere, in particular, oxygen partial pressure (pO₂), were studied. It was confirmed that sintering was promoted in regions where the pO₂ was lower than that in the air atmosphere, 0.21 atm. Our analysis of the additive using TG-DTA and XRD methods indicated that both the melting temperature and compositions of the produced compound vary with the change in firing atmosphere. These changes were presumed to affect the sintering performance. By lowering the pO₂ to 0.05 atm, a dense sintered sample with good dielectric properties was obtained at a firing temperature of 925 °C.