Effects of micro-knurling and femtosecond laser micro texturing on aluminum long-term surface wettability

A comparison of the long-term evolution of a femtosecond laser and the mechanical knurling texturing of aluminum surfaces is performed. Both the femtosecond laser and knurling textured surfaces present similar topographical parameters in the micrometer range. To compare both texturing approaches, long-term physico-chemical characterizations are performed. These characterizations consist of wettability measurements and XPS analyses as a function of time following the texturing operations. The evolution of the wetting properties over time for the femtosecond laser textured surface is explained through chemical modifications of the extreme surface. High-resolution XPS spectra highlight a C-C/C-O bond ratio evolution over time. This time evolution of the chemical bonds of the extreme surface is corroborated with the static contact angle evolution. On the contrary, the mechanically knurled surfaces present a steady state after texturing: neither the evolution of the wetting properties nor the chemical composition of the extreme surface is measured.