Abstract
During the last decades, the application of copper alloys has become very prominent in engineering. Judging from the properties of bulk materials or galvanic copper coatings, a thermal sprayed coating shows significant disadvantages. The reason for this effect is the build up of a thermal sprayed coating by individual droplets. The main aim of this work is to improve the properties of the twin wire arc sprayed copper alloys, thereby expanding the application of these kind of coatings to the areas where galvanic copper plating technique are mainly used. A copper-cobalt-beryllium alloy has been investigated and the possibility of its application in the twin wire arc process evaluated. The arc sprayed coatings were classified based on the properties of bulk material. The improvement of properties like hardness is based on an investigation of several spraying parameters of the arc spray process. To achieve a maximum value of thermal or electrical conductivity, minimum porosity of the coatings was the aim. Furthermore, a post heat treatment of the sprayed coatings, with the aim of reducing residual tensile stresses within the coating and to improve the wear resistance by means of hardening effects, was carried out. The investigations involved metallographic examination of the coatings using optical microscopy and scanning electron microscopy. Phase composition and residual stresses were detected by X-ray diffraction analysis. Microhardness was measured in the as sprayed as well as in the heat treated state.
