Enhancement in corrosion and electrical wear resistance of copper via laser surface alloying with NiTi

Abstract

With a 2.3-kW high-power diode laser, laser surface alloying of a commercially pure copper (cp Cu) with NiTi powder was carried out to attain higher corrosion and electrical wear resistances. Potentiodynamic polarization was conducted in simulated acid rain (SAR) at 25 °C for simulating the corrosive environment. In the SAR, corrosion potentials of all laser-alloyed samples are found to be nobler than those of cp Cu and NiTi alloy and their corrosion current densities are lower than that of cp Cu although their oxide layers are less uniform. Electrical wear tests were also carried out in both dry and wet conditions with a pin-on-disc tribometer. The electrical wear resistances of the laser-alloyed samples in wet condition are higher than in dry condition due to lubrication effect and reduction in frictional heat. The electrical wear resistances of all laser-alloyed samples were improved as compared with cp Cu owing to the presence of pseudo-plasticity of B19′ and hard IMPs, and work hardening effect during electrical wear. The contribution of electrical wear in SAR is mainly mechanical wear, and wear-corrosion synergism up to 36.1%, while corrosion is negligible. Compared with cp Cu, the interfacial contact resistance of the laser-alloyed samples at 50 N/cm2 has increased from 3.5 to 7.2 times.