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technical paper
Evaluation of Surface Tortuosity on the Corrosion Resistance of Organic Coatings Using Laser Textured Surfaces
keywords:
delamination rate
mechanical hooking
surface tortuosity
organic coatings
laser surface texturing
Surface tortuosity is a measure of the complexity of the surface of a material, which is typically expressed as the ratio of the length of the surface over the shortest distance between two points on the surface. This characteristic has been considered beneficial for coating/steel stability of painted parts exposed to corrosive and humid conditions. Laser surface texturing process can modify the surface tortuosity by producing different structures on the steel surface. However, due to the versatility of the process, structures with different sizes and magnitudes can be fabricated on the surface giving a wide range of possibilities. In this context, this study aims to determine the influence of the V-shaped grooves dimensions into the resistance against corrosion creep of an organic coating applied on textured surfaces. Comparative surface tortuosity was obtained with deferent grooves dimensions at equal relation aspect and textured areas. Aspect ratio of one and sizes of 50, 100 and 200 µm were fabricated on AISI-A36 carbon steel surface. Distance between adjacent grooves was varied to achieve different textured areas in the range of 10 % to 60 %. Surface roughness Rz and surface tortuosity was characterized. Coating performance was evaluated through an accelerated corrosion test based on ISO 12944-9. Results show that lower coating delamination was obtained with V-shaped grooves with 100 µm and a textured area of 40 %. Delamination of the coating was diminished by the increase of surface tortuosity only if mechanical interlock/hooking of the coating is enhanced.