The effect of TiO2 on the electrical strength of silica porcelain insulators

Porcelains have wide applications due to their mechanical properties، high electrical strength and chemical stability. However high electrical strength is the most important among those mentioned properties. The amount and morphology of mullite، the amount and viscosity of the glassy phase and the amount of quarts in the body affect these properties. In this investigation، 1-7 wt% of titania were added to Magharre Sazi Co. routine porcelain. The porcelain bodies were baked in a tunnel furnace. The electrical properties were studied according to IEC672 standard. The structure was studied using XRD and SEM. Linear shrinkage، density and water absorption of the bodies were measured. The results showed that by adding 3 wt% of titania، the electrical strength decreases to 21. 015 kV/mm due to excess formation of the glassy phase. Increasing titania to 7% caused the electrical strength to rise up to a higher level of 31. 361 kV/mm. Higher level of glassy phase and density and the presence of unsolved rutile should be considered as the reasons. Increase in titania content from 0% to 7% caused the density to change from 2. 355 to 2. 393 g/cm2. The same phenomenon was detected for linear shrinkage which changed from 7. 82 to 8. 79%. No water absorption was seen after the appropriate test.