Comparison of microstructures and properties of laser surface-treated thermally sprayed and laser-clad coatings of Inconel 625

Abstract

Laser surface treatment of thermally sprayed coatings improves their corrosion performance. However, this is a two-stage process, limiting its industrial application. Alternatively, a single-stage laser cladding technique can be used. This paper aims towards presenting a comparison between laser-treated HVOF and laser-clad coatings due to similar principles involved in both processes. Thermally sprayed Inconel 625 coatings are laser melted and microstructure and corrosion properties are compared with those obtained from laser clad coatings. Results indicate that generally dense, oxide-free, and dendritic structures are obtained in both cases with some microstructural differences. However, these variations have no influence on corrosion performance. Similar and improved corrosion properties render laser cladding, being a single-stage process, as preferred method for enhancing substrate corrosion properties.Laser surface treatment of thermally sprayed coatings improves their corrosion performance. However, this is a two-stage process, limiting its industrial application. Alternatively, a single-stage laser cladding technique can be used. This paper aims towards presenting a comparison between laser-treated HVOF and laser-clad coatings due to similar principles involved in both processes. Thermally sprayed Inconel 625 coatings are laser melted and microstructure and corrosion properties are compared with those obtained from laser clad coatings. Results indicate that generally dense, oxide-free, and dendritic structures are obtained in both cases with some microstructural differences. However, these variations have no influence on corrosion performance. Similar and improved corrosion properties render laser cladding, being a single-stage process, as preferred method for enhancing substrate corrosion properties.