Oscillating and unidirectional sliding wear behaviour of cold sprayed Ti-6Al-4V coating on Ti-6Al-4V substrate

Abstract Ti-6Al-4V components are widely used in the aircrafts engine or airframe parts, as landing gears or wing boxes, where the wear by unidirectional sliding or oscillating relative motion is one of the most recurrent damage processes. Recently, the deposition by Cold-Spray (CS) has been revealed as a promising alternative to repair these damaged components, increasing their useful time and decreasing the maintenance costs. Consequently, the wear resistance of the coatings could be improved by optimizing the CS processing parameters. In this work, oscillating and unidirectional sliding wear tests were planned to determine the wear resistance of Ti-6Al-4V coatings deposited onto substrates of the same Ti alloy by CS. The coatings were sprayed using two different values for two of the main spraying parameters. First, values of 800 °C and 40 bars were used for the process gas temperature and pressure, respectively, which are widely used spray conditions by researchers; and secondly, values of 1100 °C and 50 bar were used for both parameters, respectively. Unidirectional sliding and oscillating wear tests were performed and the effect of the testing temperature was studied. The main wear mechanisms in room temperature (RT) were abrasion and adhesion, while oxidation was also distinguished during the high temperature tests. In addition, the wear processes were more severe during the unidirectional sliding tests as compared to the oscillating tests. The results showed that the coatings deposited using the first spraying conditions presented a poor wear resistance as compared to the substrate and thus they are not adequate for repairing purposes. However, the coatings deposited using higher values of gas temperature and pressure showed a comparable, or even better, wear resistance to that of the substrate under oscillating movement.