In order to broader thermal spraying applications and reduce constraints and time due to conventional surface preparation before thermal spraying, the PROTAL process was developed over the last decade. This process integrates laser ablation, using a Q-switched Nd-YAG laser to prepare the surface simultaneously to the coating build-up during Plasma or HVOF Spraying. The present paper aimed at evaluating the feasibility to use the Protal technology in conjunction with the Twin Wire Arc deposition (Arc spraying) onto the 7075 Aluminum based alloy and to define the optimal Protal process parameters. Coating adhesion, micro-gap at coating-substrate interface and the coating residual stresses are evaluated. The Protal parameters investigated are: the laser energy density onto the substrate and the coating layers, the number of laser passes and the time delay between the laser impact. This study results indicate that it is feasible to use the Protal technology in-situ with the Arc spray process in spite of the challenging overspray and the large plume size of the Arc process. Good adherence and absence of interface micro-gap is obtained with an appropriate range of laser energy density to ablate the substrate. The use of a low energy ablation prior each coating layers reduces coating tensile residual stresses and improves furthermore the bond strength. The elimination of the process ablation dust and overspray dust prior the coating deposition onto the plane substrate was found critical to obtain a good bond strength. This research results from collaboration between the LERMPS in France and National Research Council Canada. Abstract only; no full-text paper available.

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