Improvement of the deposition efficiency and adhesion strength of cold sprayed fluoropolymer coating by laser surface texturing of the substrate

High-performance polymer cold-spraying is attracting the interest of many for its economical, time-saving, and environmentally safe features in comparison to traditional thermal spraying processes. The cold spray process allows applying functional polymer coatings on a similar or dissimilar material surface for protective measures or additional functionalities. However, its practical use has been restricted by inherently low deposition efficiency associated with a weak interfacial adhesion strength. In this study, fluoropolymer powder mixed with 5 wt% of nano-alumina was cold-sprayed on laser-textured carbon steel substrates. A thorough analysis of the particle deposition as a function of the spray parameters (gas temperature, pressure, pass number, traverse speed) was performed to highlight the effect of the laser-texturing (groove geometry, laser pitch, pattern) on the deposition efficiency and adhesion strength. By laser-texturing the substrate, the deposition efficiency increases up to 60 %, and the adhesion strength reaches 1.25 MPa. Thus, while the addition of nano-alumina enhances the interparticle cohesion, a laser-textured substrate promotes the mechanical interlocking at the particle/substrate interface.