Formation of CrxCyOz Coatings under Laser Treatment of Chromium Carbide Ceramics

The effect of the pulsed laser irradiation in air on Cr23C6 ceramic with Cr3C2 and Cr7C3 additives has been studied. It is established that the main process occurring in the zone of laser radiation is the melting of the ceramic surface of chromium carbide and the formation of a crater. This process is accompanied by the ejection of melt droplets from the crater zone and the dissociation of chromium carbides. As a result, the crater area is enriched in such ablation products as Cr, C, CO, and CO2. Reduction of hydrogen in the crater zone and neighboring areas leads to slowing down of the rate of oxidation processes, and the presence of ablation products such as Cr and C atoms promotes the process of synthesis of oxycarbides CrxCyOz (x ≈ 0.3–0.8, y ≈ 0.03–0.3, z ≈ 0.61–0.26) in the gas phase. Emission of the newly formed products of ablation from the crater and their distribution to the neighboring areas is accompanied by coagulation of nanoparticles into clusters. Depending on the length of flight of nanoclusters through different temperature zones and temperature of the deposition surface, oxycarbides with different morphology are formed: from islets (like fractal clusters) to film ones. The deposited ablation products are characterized by the signs of particle size “separation.” This makes it possible to create films of a given type and purpose. The passage of particles of different sizes through a gaseous medium containing oxygen is accompanied by the oxidation of oxycarbides to Cr2O3.