Formation of CrxCyOz coatings under laser ablation of Cr23C6 ceramics

Abstract In the work, a laser treatment of Cr 23 C 6 ceramics in air is considered. It has been established that, as a result of high-temperature laser heating, the melting of Cr 23 C 6 , formation of a crater, ejection of melt drops, and dissociation of chromium carbide (Cr 23 C 6  → Сr + C) inside the crater occur. The enrichment of the gaseous atmosphere of the crater in atomic carbon leads to the formation of a СO/CO 2 atmosphere, retardation of oxidation processes and, as a result, the synthesis of chromium oxycarbides Cr x C y O z , where x ~ (0.3–0.8), y ~ (0.03–0.3), and z ~ (0.61–0.26) in the vapor–gas phase. As the laser cloud expands, the processes of formation, coagulation and coalescence of ultra nanoparticle/clusters, and then crystallization of large formations occur. Due to the presence of particles with different sizes in the gaseous atmosphere, precipitation products show signs of “separation”: finer particles precipitate at a larger distance from the crater than coarser particles. This makes possible to obtain Cr x C y O z coatings of different morphology, namely, island-, film-, and mixed-type coatings.