Optimization of ARC Erosion Resistance of Silver Tin Oxide Electrical Contacts Prepared using the Electroless Route

The use of cadmium and cadmium oxide containing contact materials has been strongly discouraged in most parts of the world in view of the toxicity of these materials and resultant environmental and health hazards. Tin oxide has emerged as a substitute material in place of cadmium oxide as the major modern silver-metal oxide contact system for industrial application. The traditional methods of synthesis of silver-cadmium oxide composite contacts (namely internal oxidation and powder metallurgy route of co-precipitation) have been found to be unsuitable for production of silver-tin oxide contact material mainly because of incompatibility of existing compounds of tin metal that are water soluble and which can be used for co-precipitation with silver salt such as silver nitrate as well as the very slow rates of internal oxidation of tin in silver-tin oxide system as compared to that of cadmium in silver-cadmium oxide system. For synthesis of silver-tin oxide powders, a novel method based on electroless coating, has been developed. In the present work, an optimization study has been undertaken for improving the arc erosion characteristics of silver tin oxide contacts, prepared using the novel electroless route with additions of a tertiary stabilizing tungsten oxide dopant. The work has been undertaken in a Statistical Factorial Design of Experiment (SDOE) setting using the one way ANOVA technique.