Transversely excited atmospheric CO2 laser-induced damage of TiN and (Ti,Al)N coatings

Abstract

When an energy-carrying beam strikes a solid surface, the surface is sputtered and many effects on the atomic, microscopic and macroscopic scale can be observed. The morphological changes induced on solid surfaces, the shape and size of damaged area depend on the beam and target characteristics. Laser beams are frequently used in modem technology to obtain materials with certain bulk properties and different surface properties. During the last years, then has been an interest for advanced technology application of implemented ceramic thin films/coatings deposited by various methods. In this work the microscopic changes induced by laser beam on TiN and (Ti,Al)N coatings deposited on steel were studied, For this purpose we used pulsed, Transversely Excited Atmospheric (TEA) CO2 laser, operating with typical and non-typical gas mixtures. The deposited coatings and laser-induced damage after 20-340 pulses were analyzed by X-ray, optical and scanning electron microscopy (SEM). It was shown that the morphological features and damages induced during the laser irradiation depend on the pulse shape, total deposited energy and type of targets. From direct observation on microscopic scale, it can be concluded that similar coatings TiN and (Ti,Al)N showed different behaviour under pulsed laser irradiation. (C) 1999 Elsevier Science B.V. All rights reserved.