Electrical Contacts

2 Types of Silver Alloys Used for Electrical Contacts

For many years, silver has been used for electrical equipment. It also has the highest level of electrical and thermal conductivity. These characteristics make it an ideal material for electrical contacts, which are highly conductive circuit components found in switches, relays, and circuit breakers.

Silver electrical contacts have undergone various developments over the years, such as with refractory metal contacts, which contain silver alloy. The most common examples are silver-cadmium oxide (Ag-CdO) and silver-tin oxide (Ag-SnO2). Read on to learn more about these 2versatile substances and why they’re used.

Silver-Cadmium Oxide

This has been the preferred silver-based material for low-tension devices. Silver-cadmium oxide has high electrical and thermal conductivity, high arcing, contact, and welding adhesion resistance, which makes it highly durable.

There are 2 ways to produce this material. The first method is powder metallurgy (PM), which involves mixing of the alloy powders and heating them in an atmosphere-controlled furnace.The second one is through internal oxidation (IO), which is the process of forming corrosion products inside the bulk of the metal. The goal of these 2 methods is to attain a homogenous oxide dispersion of the metal oxide within the soft silver matrix, which improves its anti-welding behavior and wear-resistance functionality.

Silver-Tin Oxide

This compound is a combination of two different materials: silver and tin oxide. Like Ag-CdO, powder metallurgy and internal oxidation are used in production. Oxide dispersion within the silver matrix gives it excellent electrical conductivity. It also shows an even microstructure, which greatly influences the physical properties, such as its durability and resistance to corrosion.

This has emerged as a substitute for silver-cadmium oxide because of itsconsiderable resistance to corrosion and anti-welding properties. Silver-tin oxide adapted itsthermally stable characteristic from tin oxide, which enables it toprevent the alloy from melting when it comes into contact with an electric arc. The result is an improvement in the alloy’santi-corrosion properties.

Contact materials are chosen based ontheir electrical conductivity, resistance to corrosion, and mechanical strength. Silver electrical contacts are used and developed because theymeet the property standards needed for a contact. The 2substancesthat are used for this, which aresilver-cadmium oxideand silver-tin oxide, have abundant characteristics that continue to improve the quality of the components used for our electricalpurposes.

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