Laser-assisted chemical cleaning for oxide-scale removal from carbon steel surfaces

The article introduces a novel laser chemical processing technique for removing thin oxide layers on low-carbon steel surfaces by combining laser-induced shock waves and the chemical cleaning technique that is currently utilized in the conventional oxide-scale removal. A Q-switched Nd:yttritium–aluminum–garnet laser (wavelength 1064 nm, full width at half maximum 6 ns) induces optical breakdown in the acid solution, producing intense pressure waves which act as a noncontact scale breaker. It has been demonstrated that the novel process leads to substantial enhancement of the oxide-scale removal from the surfaces. The removal rate has been measured by optical microscopy, x-ray photoelectron spectroscopy, and energy-dispersive x-ray analysis. Parametric study has been performed to reveal the effect of laser-induced pressure pulse, acid concentration, and reaction time on the efficiency of oxide removal. This work demonstrates a technical feasibility of employing the proposed process in industrial applications which require special treatment, e.g., increased oxide-removal rate and selective surface processing.