Experimental Investigation of a Method for Selective and Precise Laser De-Coating

Abstract

Coatings are used in many industrial applications as a protective barrier, improving component properties such as friction, wear resistance, and thermal resistivity. When components become worn, any coatings must be thoroughly removed before performing repairs. Laser stripping is a relatively new technology developed for the entire coating removal. So far, only laser stripping of the entire coatings has been discussed in literature, but its application in selective de-coating layer by layercan extend the usage of this technique. Herein, we describe a new method of selective and precise laser de-coating layer by layer in layer thickness lower than 0,15 μm and demonstrate tise technique on two coatings, namely AlTiN and diamond-like carbon. This method is based on ablation threshold measurement and the application of low laser beam fluences for selective de-coating, layer by layer, in a defined pattern. Then the average minimal removals per layer were estimated for both coatings using first and second harmonic wavelengths. Finally, the usage of this method was proved by chemical analysis of the de-coated areas. The presented method can extend the use of laser coating stripping from actual removal of whole coatings to new areas, for example thickness measurement or inter-layer inspection of coatings.