Laser Patterning Pretreatment before Thermal Spraying: A Technique to Adapt and Control the Surface Topography to Thermomechanical Loading and Materials

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

Etude expérimentale de la résistance thermique de contact entre une gouttelette millimétrique et une surface solide

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Thermal contact resistance study at interface splat/substrate in plasma sprayed coating formation

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Caractérisation expérimentale des propriétés physiques et mécaniques de FGPM Ni/BaTiO3_3

International audienceThis study focuses on the experimental characterization of the physical and mechanical properties of FGM/FGPM. These materials present a controlled variation of the properties at the thickness level. Ni/BaTiO$_3$ samples have been developed by the SPS sintering technique. The variation of thermal conductivity across the thickness was determined using the transient planar source method. However, the small size of the samples does not allow the use of standard techniques to measure the elastic constants. An alternative protocol based on the use of ultrasonic waves has been proposed to overcome this difficultyCette étude porte sur la caractérisation expérimentale des propriétés physiques et mécaniques de matériaux FGM /FGPM. Ces matériaux présentent une variation contrôlée des propriétés au niveau de l'épaisseur. Des échantillons Ni/BaTiO3 ont ainsi été élaborés par la technique originale de frittage SPS. La variation de la conductivité thermique dans l'épaisseur a été déterminée à l'aide de la méthode de la source plane transitoire. Cependant, la petite taille des échantillons ne permet pas d'utiliser les techniques standard pour mesurer les constantes élastiques. Un protocole alternatif basé sur l'utilisation des ondes ultrasons est donc proposé pour palier à cette difficulté