Tungsten silver

Tungsten silver is a silver alloy composed of silver and tungsten, a binary alloy of silver and tungsten. Silver and tungsten are immiscible in both liquid and solid state. The preparation of silver-tungsten alloy can only be made into sintered material by powder metallurgy method, and extrusion method can also be used. The material is characterized by high hardness and resistance to arc erosion, sticking and fusion welding. Manufactured by powder metallurgy. Alloys with more than 60% tungsten are mostly produced by infiltration method. It is used as low-voltage power switch, lifting switch, locomotive switch, pre-contact of high-current switch, heavy-duty relay, air circuit breaker, etc. The addition of cobalt can improve the wettability of silver to tungsten and reduce the contact resistance.

Both tungsten-silver material and tungsten-copper material were made at the same time in the 1930s and used as electrical switch contacts (contacts). In the late 1950s, with the development of solid-fuel rockets, the gas temperature and pressure were greatly improved. The original pure tungsten rocket nozzle could no longer meet such conditions of use, and other materials could not meet the requirements at that time. In the early 1960s, R.E.Mott and G.G.Goetel of the United States re-studied the tungsten-silver pseudo-alloy based on the concept of "sweat cooling", including the mechanism of sweating and thermal shock resistance. Research on properties, preparation process and performance. In the mid-1960s, a tungsten-silver (W-10Ag) nozzle was developed, which was used in the "Polaris A-3" missile. Although tungsten-silver nozzles were used earlier than tungsten-copper nozzles, they were not developed later because of their high price and the successful development of other nozzle materials. At present, tungsten-silver material is mainly used as electrical switch contacts (contacts), and its contact resistance is smaller than that of tungsten-copper materials, and is mostly used in contactors.