Characteristics of Nanosecond Pulse Laser Cleaning Paint Coatings on 2024 Aluminum Alloy Surface

Herein,nanosecond laser with different pulse frequencies and pulse widths was used to remove 150 μm thick epoxy coatings from a 2024 aluminum alloy surface. The macro and microsurface morphologies of the sample cleaned by laser were analyzed,and the paint removal effect and damage to the substrate under different laser parameters were discussed. The substrate damage threshold was calculated to be approximately 556. 17 W under the pulse width and frequency of 60 ns and 20 kHz,respectively. Results show that the paint coating on the sample surface is completely removed,and the substrate surface is not melted when the laser power,pulse width,and pulse frequency are set to 500 W,60 ns,and 20 kHz,respectively. The oxygen content in the sample surface cleaned under the above parameters is 43. 44%,while that in the original substrate surface is 42. 51%,which are close to each other. The oxygen content in the cleaned sample surface and original substrate surface is approximately equal,suggesting that the anodized film on the substrate surface is not damaged during the cleaning process. After removing the paint by the above laser parameters,the microhardness of the cleaned sample surface is 168. 34 HV,which is 99. 1% of the microhardness of the original substrate surface,indicating that the microhardness of the substrate surface is unaffected by the laser cleaning paint process.