Abstract
Coating characteristics are highly dependent on substrate preparation and spray parameters. Hence, the surface must be adapted mechanically and physicochemically to favor coating–substrate adhesion. Conventional surface preparation methods such as grit blasting are limited by surface embrittlement and produce large plastic deformations throughout the surface, resulting in compressive stress and potential cracks. Among all such methods, laser patterning is suitable to prepare the surface of sensitive materials. No embedded grit particles can be observed, and high-quality coatings are obtained. Finally, laser surface patterning adapts the impacted surface, creating large anchoring area. Optimized surface topographies can then be elaborated according to the material as well as the application. The objective of this study is to compare the adhesive bond strength between two surface preparation methods, namely grit blasting and laser surface patterning, for two material couples used in aerospace applications: 2017 aluminum alloy and AISI 304L stainless steel coated with NiAl and YSZ, respectively. Laser patterning significantly increases adherence values for similar contact area due to mixed-mode (cohesive and adhesive) failure. The coating is locked in the pattern.
Highlights
New processes and materials are emerging with specific properties or endurance life and/or lower environmental impact
Surface treatments carried out by thermal spraying appear quite promising, as they can extend the life of components while improving their performance (Ref 1)
The adhesion of thermally sprayed coatings strongly depends on the substrate topography (Ref 2), substrate temperature (Ref 3), and surface composition (Ref 4)
Summary
New processes and materials are emerging with specific properties or endurance life and/or lower environmental impact In this approach, surface treatments carried out by thermal spraying appear quite promising, as they can extend the life of components while improving their performance (Ref 1). Grit-blasted surfaces are contaminant free with abrasive granules This technique is very effective for most materials, but ductile materials may be damaged with severe surface plastic deformation and/or microcracks (Ref 10). Grit inclusion can occur, decreasing the adherence of the subsequent coating New technologies such as laser tools have been developed to adjust the coating–substrate adhesion, but they suffer from some disadvantages. A controlled interaction between the laser and material enables surface modification processes for all Journal of Thermal Spray Technology
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