Electrical Contact and Electrode Materials

Electrical contact and electrode materials consist of soft, high conductivity, oxidation resistant materials, often with a second phase to provide anti-welding and/or arc-resistance. They are used in circuit breakers, relays and for EDM applications.  Additional material applications for electrical contact and electrode materials include EDM electrode materials, electrical brush / sliding contact materials, electrical contact materials, electrochemical / battery electrode, furnace electrode (arc), and welding electrode material.  Specific material types include brass, carbon-amorphous, graphite, copper, copper graphite, copper tellurium, copper tungsten, copper zirconium diboride, gold or gold alloy, electrographite, metal graphite, molybdenum, palladium or palladium alloys, platinum or platinum alloys, plated base metal, resin bonded graphite, silver or silver alloys, silver copper, silver cadmium oxide, silver graphite, silver molybdenum, silver nickel, silver tin oxide, silver tungsten, silver tungsten carbide, tungsten, and tungsten carbide.

The form or shape of electrical contact and electrode materials can be application specific or custom.  Specific shapes include assembly, bar stock, coated wire, conductive paste or coating, contact tip or button, contact rivet (shanked tip), EDM drilling electrode, electrode block or billet, pin or probe, powder, solid rod stock, socket, stamped or spring contact, sheet or foil, strip, tamped or shunted brush, tapping electrodes, tape, wire, and wheel.  The material may have a bimetal or clad overlay.  Electrodes can be machined or formed through an electroforming process.  Fine or ultrafine structured materials have better erosion and wear performance.  The contact or base metal can be plated or coated with a contact material.

Specifications and properties important for electrical contact and electrode materials include outer diameter or width, length, thickness, inner diameter, conductivity, resistivity, tensile strength, and MOR or flexural strength.  Conductivity is the inverse of resistivity.  Conductivity is often given as percent of a copper standard, which is 100%IACS (International Anode Copper Standard).  Resistivity is the inverse of conductivity.  The ultimate tensile strength is the amount of applied stress required to failure a control specimen of the material under tensile load conditions.  Modulus of rupture (MOR), cross-break strength or flexural strength (3-point or 4-point) is the maximum flexural stress a bar can withstand before failure or fracture occurs.  Two points beneath the bar support the bar and one or two points above the bar apply the load.  Cross break strength is used to evaluate the strength of ceramics or other materials that do not provide sufficient plastic deformation to reliably test tensile strength.

• The Importance of Force Control
  There are many variables associated with the resistance welding process. The three primary variables are weld current, weld time, and electrode force. Secondary variables include, but are not limited...
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