Abstract
The sintering behavior and electrical properties of glass-doped 15 m/o CaO stabilized zirconia (CSZ15) is investigated in this study. Glasses GA (29 m/o PbO-36·9 m/o B 2 O 3 -20·4 m/o SiO 2 -13·7 m/o Al 2 O 3 ) and GB (21 m/o CaO-79 m/o (11·4 m/o BaO-48·1 m/o B 2 O 3 -25·3 m/o SiO 2 -15·2 m/o Al 2 O 3 )) are proved to be effective in reducing the sintering temperature of CSZ15. The CSZ15 samples doped with 3 m/o GA can reach 96·5% theoretical density (TD) at 1350°C in 5 h. Reducing the relative CaO content of GB from 21 m/o CaO to 12·95 m/o CaO greatly reduced the effectiveness in densification. Optimum firing temperatures in the sintering of glass-doped samples are found to be around 1350°C. Higher sintering temperatures result in a density drop which is attributed to formation of porosity and/or the early onset of solid state sintering at elevated temperatures. The conductivities of undoped and doped CSZ15 are studied with complex impedance analysis. Glassy additives decrease the grain boundary conductivity, but increase the intragrain conductivity for some samples. Glassy phases located at the grain boundary block the conduction of mobile ions mainly by a grain boundary impurity film but also by constriction of the conduction path. This results in higher grain boundary resistance than in the undoped samples. Two possible mechanisms have been proposed to explain the positive effect of the glass frits on grain conductivity. © 1988.