Synthesis, parametric and tribological study of laser clad Co–Ni binary coatings on titanium alloy

Abstract

With everyday advancement in laser cladding technology, hard-faced materials have been considered as excellent candidates for tribological applications. In this study, Co–Ni intermetallics were synthesized on Ti–6Al–4V substrates using a 3 kW Rofin Sinar Ytterbium laser. Effect of the relationship between the laser parameters: powder composition, laser scan speed and laser power on the hardness values and tribological resistance of the coatings were studied. Microstructural examination and analysis were performed on resultant coatings using scanning electron microscope equipped with energy dispersive spectrometer. The coatings exhibited a good metallurgical bonding between the coatings and the substrate. Microhardness test was conducted on the coatings while the tribological behaviour of these coatings were also observed under a load force of 100 gf. The relationship between the microhardness and wear depth showed a tremendous benefit of the coatings to Ti–6Al–4V surfaces during abrasion. Phase analysis, using x-ray diffractometry, showed newly developed structures which may account for the increased microhardness values of the coatings as well as enhanced wear resistance.