The copper-plated layer has the best anti-sticking performance. The theoretical and practical history of the copper plating layer as the surface layer of the threaded anti-sticking button can be traced back to the mechanical power transmission friction pair-the anti-stick wear theory and application research history of the shaft and the bearing bush. In order to prevent the phenomenon of shaft holding, usually a layer of babbitt alloy is cladding on the surface of the bearing bush. Although the hardness of babbitt alloy is very low, but because of its good plasticity, toughness, ductility, continuity and ability to absorb abrasives, it effectively improves the anti-adhesive wear performance between the friction pairs. Afterwards, they successively developed lead-tin alloy electroplating technology on the bearing bush surface with better resistance to adhesive wear, as well as lead-tin-copper and other ternary alloys and even multiple alloy technologies. However, high temperature will be generated during the process of unscrewing the thread. Under high temperature conditions, such low melting point lead-tin-based binary or even multi-element alloy coatings should not be used. Copper plating has become the first choice for improving thread anti-sticking performance. Because the copper plating layer has the characteristics of high melting point (1083°C), low hardness, good ductility, and large difference in lattice parameters from steel materials, copper plating on the thread surface is an ideal solution to prevent thread sticking of drill pipes and tubing and casing.
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