Low voltage switchgear is characterized by high reliability and long service life.Among them, contact (especially contact material) is the key to ensure its high reliability and long life.Electric contact, also known as contact, contact or contact, is the contact parts of switch appliances, instruments and meters, which shoulder the task of switching on, carrying and breaking the current. Its performance directly affects the reliable operation and service life of switch appliances.The phenomenon of electric contact in the process of opening and closing is extremely complex, and there are many influencing factors. The ideal electric contact material must have good physical properties, electric contact properties, processing and manufacturing properties, etc.Therefore, its performance directly affects the reliable operation of switching equipment and instruments.
Low-voltage electrical contact materials has a history of more than 100 years. The silver based electric contact material is suitable for all kinds of switch, relay, contactor, etc in large, medium load.- initially use sterling silver, gold, pure platinum contact materials;By the 1940 s began to adopt Ag, Cu, Au - AgPd - Ag alloy; / to the 60 s developed multiple metal and all kinds of precious metals composites.
Silver has good conductivity and thermal conductivity, certain resistance to electrical corrosion, simple manufacturing process, price is also moderate, so many electrical appliances are made of silver contact.Silver-based electric contact has good resistance to electrical wear, resistance to fusion welding and electrical conductivity, small and stable contact resistance, widely used in various light and heavy load low-voltage electrical appliances, household electrical appliances, automotive electrical appliances, aerospace electrical appliances.In particular, relay and contactor are the most extensive electric appliances, almost all of which use silver contacts. They are the most extensive products in the electric contact industry.
silver alloy materials in order to solve the silver contact materials of all sorts of shortcomings, developed the silver alloy machine; In order to improve the hardness of silver, often join copper; In order to arc extinguish quickly and join the cadmium; In order to make the grain refinement and the nickel; In order to improve the mechanical properties, abrasion resistance, weldability and gloss and adding vanadium; In order to improve the sulfur resistance and add a small amount of tin, zinc, etc. With the development of electrical appliances, the requirement of electric contact material is becoming more and more complex, in order to solve this contradiction, developed the silver metal oxide materials.
