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2591 |
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Effects of laser treatments on cold sprayed metallic coatings |
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Sophie Costil* / IRTES-LERMPS / UTBM, France Dominique Poirier/ NRC - IMI, Canada Wilson Wong/ Mc Gill University, Mining and materials engineering, Canada Eric Irissou/ NRC - IMI, Canada Jean-Gabriel Legoux/ NRC - IMI, Canada Vincent Guipont/ Mines Paristech, France Michel Jeandin/ Mines Paristech, France Steve Yue/ Mc Gill University, Mining and materials engineering, Canada |
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Cold spraying is particularly suitable for making coatings from materials that are sensitive to heat and oxidation. This owes to the fact that the particles are not melted during the spraying process, making it possible to produce coatings without chemical modifications. Nevertheless, according to the materials considered, some interfacial defects can be detected inducing inadequate adhesion between the substrate and the coating as well as between layers. The bonding mechanisms are not only strongly dependent on the particle velocity but also on the state of the surfaces. Accordingly, surface pre-treatments can improve adhesion. From all the surface modification technologies, laser technology has the key advantages of flexibility through the use of optical fibers, as well as excellent control over the treated area. It is then possible to interact with the material during the entire spraying process on the substrate surface as well as on the interface layers. Consequently, the aim of this study is to explore the effect of a laser treatment (specifically, ablation or heating effects) on the quality of cold spray coatings, both on the surface and at the interface, on metallic substrates. While controlling the chemical composition of the materials, the coating cohesion as well as the adhesion levels, coatings were sprayed on pure titanium and titanium and nickel-based alloy substrates. Since the coating bond strength exceeded the strength limit (80 MPa) of the adhesive used for conventional pull tests for most of the different pre-treatments, other adhesive strength evaluation methods, the laser shock (LASAT), scratch, and modified ASTM C633 induction brazing tests were used to compare and quantify the adhesion strength. |