Fretting Contact Characteristics And Reliability Analysis Of Contact Pairs Of Different Coating Materials

Connectors are widely used in various kinds of electrical and electronic systems. The contact performance of the connector directly affects the reliability of the whole system, fretting is one of the important causes of the contact failure. The fretting performance and reliability of seven kinds of common coating materials are studied,by measuring the contact resistance and fretting wear characteristics,The research has reference value for connector parameter design and contact material selection.The research object is the spring and pin of 2mm connector, mainly discusses the resistance characteristics of contact material of thick Au+Ni+Cu, flash Au+PdNi+Ni+Cu, PdNi+Ni+Cu, Sn+Ni+Cu, flash Au+Ni+Cu, Cu and Ni+Cu under various working conditions such as force,temperature, lubricant. Au coating can improve the fretting resistance characteristics of the connector, and the contact resistance remains low and stable. Palladium coating material has catalytic activity. Because of the high content of organic matter in the lubricant environment, the contact resistance rapidly arrives at the threshold value and contact failure. The initial fretting contact resistance of non-precious metal materials is high,because of easily to oxidize when exposed, and the initial wiping stage is longer. The contact resistance decreases with the increase of contact force,and when the contact resistance is stable, the number of fretting cycles decreases obviously. The properties of fretting resistance are improved after a thin layer of gold is plated on the surface. Lubricant mainly plays a lubricating function and protecting the coating is not oxidation for non-precious metals, can improve the fretting contact performance. The result indicated that resistance characteristic of contact pairs are: thick Au> flash Au+PdNi> flash Au+Ni >PdNi> Cu> Ni> Sn.The fretting wear parameters and fretting wear mechanisms of seven kinds of coatings are calculated and analyzed. Non-precious metals'fretting mechanism of electric contact mainly includes oxidation of base metal, adhesive wear and electric die grinder. Palladium nickel material has catalytic activity. Because of the high content of organic matter in the lubricant environment, the friction polymer is generated during the fretting process, and the contact resistance increases rapidly. The wear rate increases with the increase of contact force and decreases with the increase of material hardness, and the wear coefficient is opposite. The wear coefficient of seven kinds of material contact pairs are thick Au> flash Au+PdNi> flash Au+Ni >PdNi>Sn>Cu>Ni.Calculation based on the Weibull distribution parameters shows that the shape parameter m of precious metals is less than that of non-precious metals, and characteristics life ? is greater than that of non-precious. The reliability analysis of several metal materials was carried out under different environmental conditions. The Au plating has the best reliability,and the palladium-nickel plating comes second.