Contacts materials performances under break arc in automotive applications

New materials for electrical contacts have been developed recently, based on AgFeO/sub x/, AgFeRe, AgZnO, and doped AgSnO/sub 2/. 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, AgSnO/sub 2/, and AgNi. Four of the new materials appear very promising: AgZnO, AgFeO/sub x/, doped AgSnO/sub 2/ io 6, and EMB8. These combine the good transfer performance of AgCdO in inductive load, i.e., in long cathodic arc, with that of AgSnO/sub 2/ in resistive load, i.e., in short anodic arc. For all materials, contact resistance is much higher in inductive load (7 m/spl Omega/) than in resistive load (1 m/spl Omega/). An explanation of the different behaviors of these materials is attempted by means of metallographic analysis.