Abstract
Laser etching characteristics of the stainless steel corrosion (oxide) films prepared under the nuclear-reactor-water-simulated conditions have been revealed. A Q-switched Nd: YAG laser of 12 ns pulse width was used to induce ablation processes. The laser beam was line-focused with a cylindrical lens and irradiated the traveling sample at different laser fluences. The etched surfaces were analyzed with a surface profiler, a scanning electron microscope, and an X-ray photoelectron spectroscope. It has been shown that the oxide films can be efficiently removed with a relatively low energy, 1064-nm laser pulse of 50mJ (2.3-2.9J/cm2). No metallic-elements-enriched layers were observed on the laser irradiated surfaces. The effects of the laser wavelength on etching characteristics was also investigated with the 2nd harmonics (532nm) and the 3rd harmonics (355nm) laser beams. It has been found that for the unoxidized samples (the bulk surface of the stainless steel) the etching efficiency increases with decreasing the laser wavelength. By contrast, no clear wavelength dependence of the etching efficiency was observed for the oxidized samples, an effect which may be attributed to relatively flat response of the absorption coefficient to the laser wavelength for the oxide films surfaces.
