High temperature tribological characterization of TiAl laser cladding coating on Ti6Al4V

Autores UPV
Año
CONGRESO High temperature tribological characterization of TiAl laser cladding coating on Ti6Al4V

Abstract

Ti6Al4V alloy has proven to be an important engineering material due to the excellent strength, weight ratio, high corrosion resistance and biocompatibility. However, the alloy is susceptible to mechanical degradation in applications involving sliding wear or abrasion. In order to improve wear resistance, coatings by laser cladding of intermetallic Ti48Al2Cr2Nb on Ti6Al4V have been developed. Different process parameters: laser power (W), scanning speed (mm/min), powder feeding rate (g/min) and preheating temperature of substrate (°C) were optimized, resulting in a microstructure of the coatings considered appropriate, with good metallurgical bond, though cracks and pores were observed [1]. The composition and microstructure of the coatings were evaluated using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, further the tribological properties were evaluated using a ball on disk tribometer, with Al2O3 ball, constant speed of 0.1 m/s, 10 N load at room temperature and 500 °C. We measure the 3D surface topography obtained from the wear scar and calculated the wear rate. The coatings microstructure consists of -TiAl phase and 2-Ti3Al. The wear test results at room temperature show a lower wear rate for the coating compared to the substrate. At high temperature the coating have a higher friction coefficient and a higher rate of wear is obtained when compared with the substrate, obtaining differences between the coatings depending on the wear mechanism observed in the worn surface.