Laser texturing of alumina surface for improved hydrophobicity

Abstract

Laser texturing of alumina surface is carried out to enhance the surface hydrophobicity. Laser controlled ablation of the surface is achieved under high pressure nitrogen assisting gas. The morphological and metallurgical changes at the surface are characterized using optical, electron scanning, and atomic force microscopes. The microhardness and the residual of the treated surfaces are measured using the X-ray diffraction technique. The contact angles at the surface are measured and the hydrophobic states are assessed. It is found that laser controlled ablation results in micro/nano texturing of the surface. Although the surface texture does not exactly follow a regular pattern, it consists of pillars and dimples like structures and the surface roughness is within the sub-micro scale. High pressure nitrogen assisting gas causes formation of AlN and AlON species at the surface while modifying the surface energy after the treatment process. The presence of AlN contributes to hydrophobicity enhancement at the surface. Wenzel and Cassie and Baxter states are present at the treated surface due to the variation in the surface texture. In general, laser texturing improves the surface hydrophobicity.