High-speed thermal plasma deposition of copper coating on aluminum surface with strong substrate adhesion and low transient resistivity

Abstract

Abstract Copper and aluminum are widespread materials and have many applications, especially in the electrical engineering, and their coupling is an important issue. The direct connection of these materials without special preparation leads to increasing the transient resistance and energy loses in the contact place. This paper shows the possibility of copper deposition on aluminum substrates using high-speed thermal plasma jet, generated by a coaxial magnetoplasma accelerator. This method allows forming the uniform coating, having the thickness from 50 to 100 μm, with the strong adhesion to the substrate. It is found that in the considered system the adhesion strength depends on the speed of the material deposition and varies from 1540 MPa to 2520 MPa. Such a strong coupling is achieved due to the presence of the mixing material zone near the interface. The material mixing and the absence of clearly-seen boundary between coating and substrate provides not only the strong adhesion but also allows reducing the transient contact resistance. The value of the transient resistance can be decreased at 2.8 times in comparison with the direct connection of copper and aluminum. The surface roughness of synthesized samples and its influence on the transient contact resistance is also investigated using profilometry analysis. It is shown that increasing the compression force can positively decrease the surface roughness that leads to increasing the contact area and, respectively, to decreasing the transient resistance.