Silver-Graphite contacts are produced through powder metallurgy and are typically supplied with either vertical or random graphite particle orientation. For specific applications, parallel graphite particle orientation can also be provided.

These contacts are commonly used in circuit breakers, motor-protective circuit breakers, fault-current circuit breakers, and power switches. Thanks to the properties of graphite, Silver-Graphite contacts are renowned for their superior anti-welding characteristics. Additionally, due to their high silver content, they offer low contact resistance.

However, the material has some limitations, including relatively low arc erosion resistance, especially during break operations, and reduced formability compared to other contact materials.

Our Silver-Graphite contacts are available as contact tips with a brazeable silver side or a brazing alloy layer.

Silver-Cadmium Oxide is a highly versatile contact material known for its excellent arc-extinguishing properties, low arc erosion, stable contact resistance, minimal temperature rise, and superior anti-welding characteristics. Though cadmium is regulated, Ag/CdO remains unmatched in different applications.

It can be produced via powder metallurgy (PM) or internal oxidation (IO), with HP specializing in both processes.

Used in applications like switches, relays, wiring devices, and contactors, our Silver-Cadmium Oxide contacts come in wires, strips, rivets, and contact tips. The typical material properties are listed in the table below, although actual contact properties may vary depending on the shape and production process.

Pure Silver offers the highest thermal and electrical conductivities among metals and is highly resistant to oxidation, making it ideal for applications like fuse tapes, push-buttons, relays, and switches. However, its low mechanical strength, high erosion rate, and tendency to weld and tarnish in contact with sulfur limit its broader use.

To enhance Pure Silver’s properties, such as mechanical strength and erosion resistance, Silver Alloys are created by adding elements like Copper and Nickel. These additions improve certain characteristics but may negatively impact contact resistance, anti-oxidation properties, and formability.

Fine Grain Silver (Ag/Ni 99.85/0.15) is produced by adding 0.15% Nickel, which reduces grain size and improves mechanical properties. It offers a better balance of strength and conductivity compared to Pure Silver. By adding Copper enhances mechanical strength, arc erosion resistance, and anti-welding properties, though it can increase contact resistance and reduce oxidation resistance. Silver Alloys are commonly used in switches, relays, and wire devices up to 20A.

Our Pure Silver and Silver-Alloys contacts are normally produced in the shape of wires, strips, rivets and contact tips and the typical material properties are listed in the table below, although actual properties may vary depending on the production process.

Silver-Nickel is a widely used contact material globally, known for its excellent properties. Due to the low solubility between silver and nickel, it is produced through powder metallurgy (PM). For Nickel contents up to 30%, the preferred method is extrusion into wires and strips, while for higher Nickel content (above 30%), Press-Sinter-Repress (PSR) is used.

Silver-Nickel contacts offer strong mechanical strength, high welding resistance, and low, stable contact resistance throughout their lifespan. They also feature superior arc resistance and excellent arc-moving and extinguishing properties. A key advantage is their ability to be directly welded onto copper carriers from wire, eliminating the need for brazing alloys, leading to significant cost savings in automated welding lines. However, this limits Silver-Nickel applications to currents up to 100A unless combined with other materials like Silver-Graphite.

Common applications for Silver-Nickel contacts include relays, switches, wiring devices, thermostats, contactors, and motor protective circuit breakers.

Our Silver-Nickel contacts are normally produced in the shape of wires, strips, rivets and contact tips and the typical material properties are listed in the table below, although actual contact properties may vary depending on the shape and production process.

Silver-Tin Oxide is a widely used contact material, often replacing Silver-Cadmium Oxide due to its non-hazardous nature. It offers excellent arc-extinguishing capabilities, very low arc erosion, and stable, low contact resistance throughout the device’s lifetime. Additionally, it exhibits minimal material transfer under DC load, low temperature rise, and exceptional anti-welding performance.

Silver-Tin Oxide can be produced using two main methods: powder metallurgy (PM) and internal oxidation (IO), each with various process options. In both methods, the selection of additives can further enhance the material’s electrical performance and formability. We have extensive expertise in these processes, and the optimal method is selected based on the specific requirements of the contact material and customer application

Our Silver-Tin Oxide contacts are normally produced in the shape of wires, strips, rivets and contact tips and the typical properties of this material are listed in the table below although actual contact properties may vary depending on the shape and production process.

Silver-Zinc Oxide is another alternative contact material used as a replacement for Silver-Cadmium Oxide. It is typically found in lower-current switches, relays, and contactors. As a non-hazardous material, Silver-Zinc Oxide offers several key benefits, including very low arc erosion, stable and low contact resistance throughout the device’s lifetime, and excellent anti-welding properties.

The Silver-Refractory Material family includes Silver-Tungsten (Ag/W), Silver-Tungsten Carbide (Ag/WC), and Silver-Molybdenum (Ag/Mo), which are specialized arcing contact materials used in high fault current applications such as residential circuit breakers, industrial breakers, and high current switchgears.

These materials combine the excellent electrical and thermal conductivity of silver with the high arc resistance, hardness, and thermal resistance of refractory metals and their carbides. This results in a composite material that offers low contact welding, low erosion under arcing, and very high resistance to arc erosion, even under high currents. While they provide high hardness and acceptable contact resistance, they exhibit poor arc moving properties. Additionally, the microstructure and properties of these materials can be highly customized based on the process used, allowing them to be tailored to meet the specific application requirements of the customer. The table below compares these contact materials.

For some special applications that require lower temperature rise or lower contact welding, graphite can be added to the alloy. The disadvantage is a lower arc resistance.

Our Silver-Refractory Material contacts are normally produced in the shape of contact tips and the typical material properties are listed in the table below, although actual contact properties may vary depending on the shape and production process.

Copper-Tungsten (Cu/W) is a contact material commonly used for electrodes or high power switching in medium and high voltage applications. While the properties of Cu/W materials are similar to those of Silver-Tungsten (Ag/W), Cu/W is significantly more cost-effective. However, it cannot fully replace Ag/W due to the inherent stability of copper oxides at high temperatures, which can drastically affect contact resistance. As a result, Cu/W is typically used in applications where the contact tip is protected from oxidation or in applications that the arc resistance is more important than conductivity. We supply Copper-Tungsten in the form of contact tips, and it can also be machined into complex shapes to meet specific customer requirements.

Ag/Pd alloys resist corrosion, fretting, and contact degradation. They provide stable electrical performance in low-load signal switching, even under exposure to chemicals, humidity, or vibration. Preferred in telecommunications, aerospace systems, and precision electronics where long-life and reliability are non-negotiable.