Influence of Structure on the Properties of Coatings During Multi-Chamber Detonation Spraying of Al₂O₃ Powder on Steel

Modern industry, including the energy, chemical, aircraft and space industries, uses products whose operational reliability depends on the characteristics of their surface layers. These parts and assemblies include the surfaces of combustion chambers, sealing connectors of prefabricated gas turbine housings, tension rollers for the paper industry, etc. To improve the performance and durability of products, various methods of surface treatment are used. The most promising is the application of functional coatings to their surfaces. In the present work, we investigated coatings made of Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> aluminum ceramics (Amperit $\mathbf{7 4 0. 0}$ powder, fractions $\mathbf{5, 6}.. \mathbf{2 2, 5} \boldsymbol{\mu m}$; Alumina TSP99Plus powder, fractions 5...30 $\mu \mathrm{m})$, formed by the method of multi-chamber detonation spraying (MCDS). The multi-chamber design provides high velocities of detonation combustion products ($1.8 \mathrm{~km} / \mathrm{s}$) and powder material movement $(1.2-1.6 \mathrm{~km} / \mathrm{s})$. It has been established that a $300 \mu \mathrm{~m}$ thick coatings with a porosity of $1 \ldots 2 \%$ and a microhardness of $7630 \ldots 11490 \mathrm{MPa}$ is formed during the MCDS. Transmission electron microscopy studies have revealed features of the fine structure of the sputtered coating. A substructure with a size of $100 \ldots..300 \mathrm{~nm}$ is formed in the coating material in the presence of nanoparticles with a size of $10 \ldots 100 \mathrm{~nm}$ and a uniform distribution of dislocation density. The formation of the nanostructural state in the materials of the obtained coatings is ensured by the technological parameters of the high-speed LBM process. This leads to a set of physical and mechanical characteristics of the surface layers of Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> aluminum ceramics, namely, their strength and crack resistance.