MODIFICATION SURFACE OF HEAT-RESISTANT VH9L CASTING ALLOY BY LASER PULSE OXIDATION IN AIR

10.25712/ASTU.1811-1416.2025.04.011

Abstract

Experimental studies of the process of laser thermal treatment of the surface of the heat-resistant casting alloy VН9L in the mode of pulsed radiation generation have been carried out. By means of laser pulse scanning oxide coatings with thickness of 20-30 μm with microhardness of 8-11 GPa are obtained. Using raster electron microscopy, the structure of the formed thermal oxides was studied depending on the power of pulsed radiation. A kinetic model of laser oxidation of metals in the composition of the VН9L alloy in air was built by the mechanism of surface nucleation. By increasing the laser power from 150 W to 200 W, the degree of oxidation of the metal surface decreases from 26% to 12% due to an increase in the metal temperature and the tendency of the formed oxide to decompose. The calculated values correspond to the obtained experimental data with a critical nucleus size of 0.3 nm, atomic oxygen desorption heat of 350,000 J/mol and a total processing time of 0.02 s. It was found that during laser oxidation of samples from alloy VН9L, the formed oxide phase mainly includes chromium and titanium oxides. The content of iron and nickel oxides in the modified surface composition is insignificant and corresponds to trace micro-quantities. It has been shown that laser pulse oxidation can be used as a promising modification method when producing mechanically strong and corrosion-resistant metal oxide films and coatings on articles.