Study on New Types of Environmental Protection AgSnO2 Electrical Contact Materials

Abstract

AgSnO2 contact materials have begun to replace toxic AgCdO materials in switching devices such as contactors and circuit breakers since 1970s [1,, which is partly due to the fact that AgSnO2 materials have shown higher service lives, better welding resistance and less arc erosion in contactors of larger size [. Furthermore, the growing awareness of environmental problems makes it desirable to replace AgCdO contact materials [. However, these materials suffer from an inadequate welding behavior compared with AgCdO [. It was observed that AgSnO2 made by traditional metallurgical process exhibited high overtemperatures attributed to high contact resistance caused by surface layers of accumulated SnO2, which was due to the poor wettability of SnO2 grains in the silver melt in combination with their high thermal stability [6,7]. Another important point was the large size and high hardness of SnO2 particle prepared by traditional process, which reduced the workability of AgSnO2 contact materials [8]. In this work, the authors prepared Ti4+-doped SnO2 using sol-gel technique and investigated the microstructure, size, distribution and crystallization of Ti4+-doped tin oxide grains as well as the doping effects on the electrical conductivity of these materials.