Study of structural changes and effect of alloy addition of ceramic materials by x-ray and neutron diffraction technique

Abstract

Investigation on the structural changes of ceramic insulator materials, with a view to improve their quality, were undertakcn. For this purpose a number of clays were mixed with up to 4 per cent potash feldspar (to reduce the firing temperature) and then fired. Alkaline earth oxides, i.e., zirconium silicate, zinc oxide, titanium oxide, manganese oxide etc. from 2 to 4 per cent werc also used as fluxing materials. Effects of alkaline earth oxides on the strength, texturc, and somc thermal properties were investigated. The influence of these alkaline earth oxides on the reaction during firing was studied by DTA. The phases were identified by x-ray diffraction and the texture was analyzed by neutron scattering technique. It was found. in the present investigation that the addition of alkaline earth oxides lowered down the firing temperature, promoted the growth of mullite and tridymite phases, and eliminated the textural defects of the ceramic insulator body. Zirconium silicate and zinc oxide were appeared to have the best influence on increasing the strength and decreasing the coefficient of thermal expansion of the material. Although a combination of zirconium silicate and titanium dioxide addition lowered down the density of the material in an encouraging level, the strength values of these materials, howcver, could not match this achievement. Rather a disappointing finding relating to the addition of a combination of oxides is probably due to the presence of a higher percentage of titanium dioxide in the body composition. Clearly, more work is required to clearify this observation.