Tribological behaviour of laser synthesized Ti-Al2O3 coatings on Ti-6Al-4V alloy

Abstract

Titanium alloy (Ti-6Al-4V) is one of the materials used in most engineering applications due to its excellent combination of mechanical and corrosion properties. However, the extend application of Ti-6Al-4V alloy is limited because of low hardness and poor wear resistance. In order to overcome this alloy’s limitations, coatings could be fabricated on the surface of the alloy through surface modification technique. In this work, Ti and Al2O3 powders were deposited using laser cladding at different admixed ratios (95Ti-5Al2O3, 92Ti-8Al2O3 and 90Ti-10Al2O3) on Ti-6Al-4V alloy. The coatings were laser cladded at laser power of 900 W, powder feed rate 2.0 g/min, beam spot size 2 mm and gas flow rate 8.0 L/ min while scan speed was varied at 0.6 and 0.8 m/min. The produced coatings were characterized for microstructures and phase constituents by using optical microscope (OPM), scanning electron microscope (SEM) and X-ray diffractometer (XRD). Moreover, Vickers hardness tester and and pin-on-disk Anton Paar tribometer were respectively used to measure hardness and wear resistance. The results showed that hardness values and reduction in wear loss were improved by increasing the Al2O3 content from 5 to 10 wt% in Ti-Al2O3. However, high scan speed of 0.8 m/min prompted non-uniform distribution of Al2O3 which in resulted low hardness and wear resistance compared to coatings fabricated at 0.6 m/min.