A study of the surface products on zinc-coated steel during laser ablationcleaning

A high-power short-pulsed Nd:YAG laser was focused onto carbon steel target s with a 13-mum-thick Zn coating. The ablation effects, the behavior and th e characteristics of the laser-induced products were studied. The ablation rate was defined as the ablated volume divided by consumed laser energy, an d nas used as a description of ablation cleaning ability. The dependence of ablation rate on laser fluence was plotted, and the optimum processing con ditions were determined. The laser induced products consisted of plasma-vap or and Liquid particles. The length of the laser-induced plasma-vapor was a pproximately 2 cm and its existence time wavered at approximately 4 mus. It was observed that the moving direction of the liquid particles was in a sm all angular range that was tilted toward but symmetric to the incident lase r. It was further noticed in this range that a higher moving velocity was o btained when the angle between the liquid particles and the incident laser beam was larger. The estimated highest moving:velocity of the liquid partic les was approximately 0.8 m/s. The analysis of the condensed particles conf irmed that the laser-induced product on the target surface consisted of Zn and Fe, which mainly solidified from plasma-vapor and melt, respectively. ( C) 2001 Elsevier Science B.V. All rights reserved.