Sintering of MgAl2O4 in the Presence of Liquid Phase

Abstract

Highly dense ceramics have ever wider application in production of components of instrumental parts, functioning at high temperatures. One of the materials often used is sintered MgAl2O4. In this paper the results obtained on the sintering of partially synthesized spinel powder in the temperature range 1500–1850°C with additions of SiO2 and SiO2 and CaO mixture (molar ratio = 2:1) are presented. By addition of SiO2, the densities up to 92%TD can be achieved, while addition of SiO2 and CaO mixture can produce 97%TD. Higher densification rate by adding above mentioned materials, in respect to the partially synthesized spinel powder densification, is achieved by liquid phase formation but only in these cases in which liquid phase enables better packing and development of favourable microstructure. Optimal quantity of additives for obtaining dense spinel material, varied with the sintering temperature under our experimental conditions.