Contacts materials performances under break arc in automotive applications

New materials for electrical contacts have been developed recently, based on AgFeO_x, AgFeRe, AgZnO, and doped AgSnO₂. The work described here aims at evaluating the material transfer characteristics, and the contact resistance behavior, of these materials under break arc in automotive applications (14 V DC, 30-40 A). A comparison is made between these new materials and four reference materials: Ag, AgCdO, AgSnO₂, and AgNi. Four of the new materials appear very promising: AgZnO, AgFeO_x, doped AgSnO₂ io 6, and EMB8. These combine the good transfer performance of AgCdO in inductive load, i.e., in long cathodic arc, with that of AgSnO₂ in resistive load, i.e., in short anodic arc. For all materials, contact resistance is much higher in inductive load (7 mΩ) than in resistive load (1 mΩ). An explanation of the different behaviors of these materials is attempted by means of metallographic analysis