Abstract
Excepted in a few cases where metallurgical bonding occurs between deposit and substrate, thermal spray deposit adhesion generally results from a mechanical anchoring. In this case, the very first impinging particles forming the first deposited layer spread and solidify into and around the cavities of the grit-blasted surface. A palliative process to degreasing and grit-blasting prior to thermal spraying is simultaneous laser ablation; i.e., the PROTAL process. In such a case, little topographic change results from the laser-matter interaction: deposit adhesion does not derive anymore mainly from mechanical anchoring but from other types of bonding such as chemical bonding. This paper aims to clarify the bonding mechanisms of thermal spray coatings manufactured implementing the PROTAL process. The case of metallic coatings deposited on metallic substrates is especially discussed. At first, laser ablation effects on various metallic substrates are presented, from the topographic and energetic points of view. Then, the induced effects on impinged particle morphologies are discussed. The results are correlated to thick deposit adhesion.
