How is silver used in making electrical contacts?

Silver finds a wide range of uses that extends beyond jewellery. It is known to have the lowest contact resistance and high conductivity. This makes it an essential component of solar panels, chemical-producing catalysts, automobiles, appliances, and electrical switches. It is considered the perfect substance for coating circuit boards.

This is the reason for the popularity of silver contact. It is a component used for regulating electricity from circuits to devices. Hence, it plays an important role in the functioning of various equipment and appliances we use. Now that we know why silver gets used extensively, it is essential to understand how.

Pure silver: Silver is used in its finest form to get the highest electrical and thermal conductivity. It offers qualities like chemical resistance, no corrosion, formability, and cladding ability. The contacts plated with it get used in several electrical switching devices. These include switches, relays, and appliances, which require low current. It is usually alloyed with minor Nickel content to get higher wear resistance, braze ability, and weldability.

Silver Nickel: This combination is used to get increased benefits from silver electrical contacts. Here, both materials are manufactured via the powder metallurgy process. This is because they are insoluble with each other in a liquid state. They offer higher strength, current carrying capacity, and erosion resistance. They also maintain contact resistance throughout their lifespan. They get mainly used in relays, switches, contactors, and thermostats.

Silver Tungsten: This is another contact material extensively used in making circuit breakers and power switching devices. Here, silver’s robust conductivity gets combined with tungsten’s high melting point. Its ability to withstand mechanical and electrical wear makes it ideal for oxidising atmospheres.

Additionally, silver tungsten carbide is an excellent material to resist contact sticking or welding. It is comparatively harder to silver tungsten. Hence, making it more averse to arc erosion and contact wear. Nonetheless, it is advantageous to combine both tungsten and tungsten carbide with silver.

Silver Cadmium Oxide: This material is useful where there is a high electrical load. Its manufacturing involves internal oxidation and powder metallurgy. It is the popular combination used for making silver contact. Besides, it is an excellent conductor of electricity. It also has good arc extinguishing properties and low contact resistance. This means it gives reliable protection against the high current.

Silver Graphite: It is a commonly found material in sliding contacts. The reason being its good lubrication. Moreover, it has anti-welding, low erosion, and reduced contact resistance properties. It gets manufactured using a sintering process. This means fusing particles into one solid mass by applying pressure. It retains the properties offered by pure silver with the advantages of graphite.

Silver Palladium: It is used to get a harder finishing to the electrical contact plating. It is because pure silver is soft and malleable. This combination is apt for resistance from Sulphur, abrasion, and burning. It is available as wires, rivets, contact tips, etc.

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