A Study on the Surface Chemistry of Laser Textured Parts

The research investigates the changes in the surface properties and surface chemistry following laser microtexturing of stainless steel parts, in relation to their applications in the energy sector. In particular, the material compositions of the laser surface textured (LST) parts, together with the oxide compound formation on them are evaluated with respect to their wettability property. Wettability is crucial for heat exchange processes as it affects the efficiency of heat transfer by influencing surface contact and the formation of droplets on the heat exchanger surface. Here, two simple LST geometries, viz. channel and cross-hatch, were produced using a nanosecond fibre laser micromachining system. The wettability of the textured surfaces was then examined over a period of 45 days with an interval of 15 days. It was observed that the former geometry rendered a hydrophilic surface initially, which transformed to a hydrophobic surface after 45 days, whereas the latter LST design exhibited hydrophobic characteristic over the entire duration of the assessment. The material compositions and the oxide compound formation on the LST parts were analysed via energy dispersive spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction techniques and the results were correlated with the measured wettability data.