Experimental study on surface decontamination by laser ablation

A high-power pulsed Nd:YAG laser was employed to irradiate a 20-μm-thick Zn coating on a carbon steel surface. The ablation rate was defined as ablated volume divided by consumed laser energy, and was used to assess ablation cleaning ability. The relationships of ablation rate to laser pulse width and ablation rate to laser fluence were investigated, and optimal processing conditions were determined. The influence of incident laser angle on ablation rate was not considerable as the angle was within 90°–20°. The behavior of the laser-induced products was studied. It was found that the products consisted of vapor and liquid particles, and that the moving direction of these particles was strongly dependent on incident laser angle. A smaller incident laser angle provided the focusing lens better protection from the pollution of the ablated products. Microprofile measurements and composition analyses were performed to estimate the cleaning effects of laser ablation. Results show that the Zn coating was removed completely and satisfactory cleaning was obtained.