Electrospark Cu[sbnd]Ti coatings on titanium alloy Ti6Al4V: Corrosion and wear properties

Abstract

Nowadays, copper-titanium coatings have invited extensive attention from researchers in the surface modification of industrial and biomedical materials due to their excellent mechanical properties and biocompatibility. The electrospark deposition technique was used for CuTi coatings deposition on the Ti6Al4V alloy by processing in a mixture of copper and titanium granules at a copper concentration from 10 to 90 at.%. For the first time, electrospark CuTi coatings with a wide range of copper and titanium ratios are obtained on Ti6Al4V titanium alloy. It is revealed that both cathode mass gain and coatings thickness rise with the copper concentration increase in the mixture of granules. According to EDS analysis, the copper concentration in the coating linearly grew with a growth of its content in the mixture of granules. According to the data of X-ray analysis, intermetallic compounds were found in the structure of the coatings: CuTi3, CuTi, Cu4Ti3, and Cu3Ti. Detected phases provide the coating microhardness up to 6.7 GPa. Polarization tests in 3.5 % NaCl solution showed corrosion resistance growth with a copper content decrease in CuTi coatings. The oxidation resistance at a temperature of 900 °C grows with an increasing copper concentration in the coating structure. Cu-enriched sublayer is formed on upper layers of Ti6Al4V alloy after CuTi coating oxidation at 900 °C. The wear rate of the coated samples as a function of copper concentration had the form of a parabola, with a minimum for the coating made in an equimolar mixture of copper and titanium. The use of electrospark CuTi coatings makes it possible to increase the wear resistance of the Ti6Al4V alloy surface up to 11 times.