Influence of Ti-6Al-4 V and Al 2017 substrate morphology on Ni-Al coating adhesion - Impacts of laser treatments

Surface morphology, chemical composition and surface state are important parameters for the formation of thermally sprayed coatings. More precisely the temperature, wettability, geometry and degree of the surface contamination play an important role in the coating particularly from the adhesion point of view. Several surface preparations (degreasing, high pressure water jet, grit blasting ... ) before thermal spraying are often used in order to obtain deposits with a good interfacial adherence. In this paper we report on an original laser surface treatment which uses two Nd-YAG laser beams in conjunction with a thermal spray gun in order to modify the substrate surface prior to thermal spraying in order to enhance the adhesion at the coating substrate interface. A first Nd-YAG laser is used to heat the surface and a second to clean it. The system is used to coat two different materials (titanium Ti-6Al-4 V and aluminium 2017 alloy) with a Ni-Al alloy. The relation between the surface modifications induced by these treatments and the adhesion of the coatings on the substrates are studied. (C) 2010 Published by Elsevier B.V.