Infrared laser ablation and atomic emission spectrometry of stainless steel at high temperatures

Laser-induced breakdown spectrometry has been evaluated at high temperature s for stainless steel samples. A Q-switched Nd:YAG laser operating at 1064 nm was used to create a microplasma on an AISI 304L stainless steel sample placed inside a laboratory oven. The steel sample was 51.5 cm away from the focusing lens. The temperature of the samples ranged from 25 to 1200 degre es C. The plasma light was collected by means of a fiber optic bundle, spec trally resolved and then detected by a CCD camera. The effects of sample te mperature in the formation of a laser-induced plasma have been studied in t erms of its spectral features as well as the morphology of the ablated crat ers in air at atmospheric pressure. A noticeable dependence of signal emiss ion intensity on sample temperature has been found. Depth profiling of stai nless steel samples for several temperature conditions was performed. Resul ts have revealed changes in the superficial composition at temperatures abo ve 600 degrees C due to the formation of a slag layer of variable thickness , mainly composed of chromium, iron and manganese oxides.