kontaktanyagok

Kontaktanyagok, or contact materials, are specialized materials used to form electrical contacts in devices such as switches, relays, circuit breakers, and connectors. They must combine low contact resistance with high conductivity, mechanical robustness, good wear resistance, and stability under arcing and environmental exposure. The performance of a contact depends on current type and duration, switching frequency, temperature, and the contact geometry.

Common classes include base-metal alloys and oxide-filled silver alloys. Copper and copper alloys, such as phosphor bronze and beryllium copper, provide strong, ductile bases for springs and blades. Silver-based materials are favored for their high conductivity and arc-quenching properties; these are often alloyed with oxide powders to improve durability. The widely used oxide-filled silver alloys include AgCdO, AgSnO2, and AgZnO. For demanding high-current or high-temperature service, copper-tungsten or copper-molybdenum composites, or tungsten carbide coatings, may be employed to resist welding and erosion.

Selection considerations include current rating, contact resistance requirements, make/break duty, arc duration, ambient conditions, and cost. In practice, low-power or signal contacts may use pure copper or copper alloys with minimal coatings, while high-reliability or high-current applications favor oxide-filled silver alloys or hard-containing composites. The goal is to balance conductivity, wear resistance, and arc performance to achieve a long service life.

Reliability challenges involve arc erosion, welding of contacts upon closure, surface contamination, and mechanical wear. Ongoing research seeks improved oxide formulations, coatings, and composite designs to extend life and reduce arcing damage.