Research On The Electrical Properties Of Doped AgSnO₂ Contact Materials In Vehicular Relay

The vehicle relay,whose performance directly influences the reliability and safety of automobile operation,undertakes the important tasks in adjustment,control and protection of the automotive electrical system.The fault of the vehicle relay mostly occurs in the contact part,which is closely related to the electrical contact properties of the contact material.So it is of great significance to research the electrical contact properties of vehicle relay contacts.AgSnO₂,one of the contact materials that commonly used in vehicle relay,has some defects in the AgSnO₂ contact material itself.Firstly,SnO₂ is easily enriched on the surface of the contact,which results in a sharp increase of the contact resistance.Secondly,it's difficult to process into complex shapes due to the poor combination of Ag and SnO₂ interface.The addition of trace additives effectively improves the electrical contact properties of AgSnO₂ contact materials,and the electrical contact properties of AgSnO₂ contact materials vary greatly at different current levels.Therefore,researching the influence of current level on electrical properties of doped AgSnO₂ contact materials,and analyzing the current application range of doped AgSnO₂ contact materials,so as to make the vehicle relay more reasonable to use AgSnO₂ contact materials,play a very important role in improving the reliability of relay and the safety of overall vehicle.In this paper,AgSnO₂,AgSnO₂/Bi₂O₃,AgSnO₂/La₂O₃,AgSnO₂/TiO₂,four electrical contact materials,were prepared by powder metallurgy method.Then,the electrical contact properties of four types of contact materials were tested by using the JF04C electrical contact material testing system under 7 different current levels of DC14V voltage.And then the contact resistance and arc energy parameters were obtained.The influence of current level at DC14V voltage on the electrical contact properties of the doped AgSnO₂ contact materials and the microstructure of the contacts were analyzed.According to the results of electrical contact test and microstructure analysis,the application current range of doped AgSnO₂ contact materials under DC14V voltage was determined.At the same time,taking into account the trend of the automobile power supply system from 14V to 42V,the electrical contact properties of four types of contact materials were tested by using the same method under 4 different current levels of DC42V voltage.And then the contact resistance and arc energy parameters were obtained.The influence of current level at DC42V voltage on the electrical contact properties of the doped AgSnO₂ contact materials and the microstructure of the contacts were analyzed.According to the results of electrical contact test and microstructure analysis,the application current range of doped AgSnO₂ contact materials under DC42V voltage was determined.