Preparation and investigation of the structure and properties of Al2O3 plasma-detonation coatings

Using a specially designed and constructed plasmatron, combining the plasma and detonation technologies, aluminum oxide coatings with high adhesion and strength (19.8 GPa) were obtained for the first time. The samples were studied by the transmission electron microscopy and X-ray diffraction methods and characterized for the first time by the Rutherford backscattering and proton elastic resonance measurements. It was found that the aluminum oxide coatings are composed of 0.20–0.25 μm crystallites, belonging to the α-, β-, γ-, and δ-Al₂O₃ crystal modifications, and have a transition region containing AlFe nanocrystals with a size of 20–40 nm and a considerable dislocation density. The aluminum oxide coatings exhibit significant carbonization, with a maximum carbon concentration on the surface reaching 20 at. %. The relative phase composition calculated using the X-ray diffraction data is as follows: γ-Al₂O₃, 60%; α-Al₂O₃, 30%; β-and δ-Al₂O₃, balance to 100%.