Study of the structure of coating of the copper-clad steel wire obtained by «freezing-out» method

Abstract

The results of studying the structure of the coating obtained by «freezing-out» method with a preliminary surface preparation including application of the underlayer or precoat by cladding with a flexible tool (CFT) are presented. The CFT procedure consists in coating with a rotating cylindrical metal brush. The developed technology of coating using «freezing-out» with the preliminary application of the precoat makes it possible to exclude harmful and labor-consuming galvanic operations. The effect of technological parameters on the quality of CFT-formed coating, i.e., the structure of the interface between the steel-copper system and data of durometric measurements of the microhardness of the copper layer and the steel core were analyzed. Elastic-stress states in the surface layer of the core and in the copper coating were determined using X-ray tensometry by the method of oblique survey. The effect of the underlayer of various materials (copper, brass, tin, tin-lead alloy) on the adhesion of the main copper coating to the core after «freezing-out» copper was studied using an adhesimeter. A fractographic analysis of the destroyed coating surfaces was also carried out. The distribution of metals in the border zones of the steel-copper compound is determined. Camscan scanning electron microscope and X-ray microanalyzer Link exL are used to examine the zone structure for the presence of intermetallic compounds. The developed «freezing-out» procedure with a preliminary application of the undercoat by CFT method is environmentally friendly, easy to use and low-power-consuming technology.