Improvement of Aluminum Coating Behaviours by Hybrid Process Including Plasma Spraying and Laser Ablation

Faced with ever growing technical, economic, as well as environmental requirements material transformation and especially surface treatment industry must be source of innovations to be proactive to answer current issues properly. As a result, developing new alternative solutions has become a top priority. But conventional thermal spray processes do not allow to consider this approach since the process itself do not permit to guarantee the lifespan of the initial composition, nor do they ensure a sufficient homogeneity to the coating structure.

If indeed the dry surface treatment processes have already shown big potential, several limits remain such as sometimes an inefficient adherence, low powder coating outputs costly, or almost no materials on the market.

To overcome these problems hybrid coating technologies (combining several processes) are likely to be developed. From all of them, laser technology seems to be very promising due to its high flexibility considering all the potential parameters and the localised treated area. For instance, combining simultaneously a laser with a thermal spray process enables the elaboration of a thick coating showing a good adherence. The ablation laser applied on the substrate surface just before the impacting particles as promoted in the PROTAL^® process permits to insure a perfect surface state favourable to the particles adhesion. The control of the coating microstructure has not been so much studied. That is why, to complete the knowledge in this area, this work aims at studying the influence of laser technology in association with plasma spraying on the coating microstructure and more precisely on the coating mechanical properties. Coatings were characterized by SEM and porosity level was evaluated. Mechanical properties were measured for evaluating the coating Young modulus and the breaking point. As a result, to meet ever growing technical requirements, this scheme aims at elaborating new coatings with improved properties.