Characterization of Doped Titanium Oxide Varistor Powder Processed with Latex Binder

Abstract

In the processing of semiconducting electro ceramic materials the use of appropriate binder can lead to improve characteristics of powder which will reduce density gradient in the green body during compaction. The binder system is anticipated to have an influence on the grain growth and microstructure which in turn affect the electrical performance. To investigate this phenomenon, TiO2 powder doped with tungsten oxide (WO3), silicon oxide (SiO2) and bismuth oxide (Bi2O3) was processed with and without various percent of latex binder. The prepared samples were characterized by evaluating the physical properties like green density, fired density, axial and radial shrinkage, micro hardness and compressive strength. It was observed that TiO2 processed with latex binder exhibited higher green density and less axial and radial shrinkage compared to powder processed without binder. However, the binder level did not have any significant influence on the other characteristics of varistor discs. SEM analysis indicated that the average grain size was also influenced by the percent of binder used and but the higher average grain size was obtained for discs without any binder.