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.
