ROYASLOT88 RTP SLOT The contact material is chosen for its resistance to corrosion, because most metals form insulating oxides that would prevent the switch from working. Contact materials are also chosen on the basis of electrical conductivity, hardness (resistance to abrasive wear), mechanical strength, low cost and low toxicity. The formation of oxide layers at contact surface, as well as surface roughness and contact pressure, determine the contact resistance, and wetting current of a mechanical switch.|Devin Lewis Fuller (Born January 24