알루미늄 6061시편의 표면 거칠기에 따른 페인트 마모 양상

초록

This study systematically investigates the influence of surface roughness on the durability and ero sion–wear behavior of paint coatings applied to aluminum 6061 substrates under high-velocity rain erosion con ditions. Aluminum specimens were mechanically polished using abrasive papers ranging from #60 to #2000 to achieve distinct average roughness (Ra) levels. Each specimen was subsequently coated with a uniform layer of fluorescent paint and tested using a custom-built rain-erosion apparatus equipped with a rotating jig and a high pressure nozzle, generating a relative impact velocity of 231.34 m/s. Confocal laser microscopy and quantitative image analysis revealed that coatings on highly rough surfaces (#60) suffered severe delamination, microcrack propagation, and localized coating loss due to stress concentration at surface asperities. Conversely, specimens with moderate surface roughness (#120, Ra ≈ 0.65 µm) exhibited uniform coating morphology, minimal defect formation, and an almost negligible delamination ratio, indicating improved coating adhesion and mechanical integrity. Although ultra-smooth surfaces (#2000) provided good initial uniformity, partial coating detachment and reduced erosion resistance were still observed after prolonged testing. These results demonstrate that an opti mum, intermediate surface roughness enhances both adhesion strength and erosion resistance of paint coatings. The findings provide valuable guidance on surface pretreatment and coating design for high-speed applications such as wind turbine blades, aircraft components, and energy conversion systems.

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