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The work presents the results of the corrosion resistance study of composite coatings obtained by cold spraying of the aluminum and boron carbide powder mixture on the surface of 08Cr18Ni10Ti austenitic steel. Their chemical and phase compositions, macro- and microstructure, as well as the effect of subsequent heat treatment are analyzed. It is shown that the corrosion of coatings in a 2% boric acid solution at 60 °C is accompanied by an increase in the sample mass and the formation of an aluminum oxide layer. The minimum mass change was observed in case of the coating heat treated at 400 °C, while an increase in heat treatment temperature leads to the intensification of corrosion destruction. [ABSTRACT FROM AUTHOR]

Abstract—The effect of thermal treatment on the microstructure, phase composition, and microhardness of Ni + B4C composite coatings is studied. The coatings are deposited onto the surface of an austenitic steel by cold gas-dynamic spraying. The initial coating is shown to be a nickel matrix containing distributed B4C particles. Thermal treatment causes diffusion processes in the coating, which results in the formation of Ni3B and Ni2B compounds. The average microhardness of the initial coating is 3.4 GPa, and heat treatment results in an increase in the coating microhardness due to the formation of hard nickel borides. [ABSTRACT FROM AUTHOR]

This paper describes how the method of preparing a composite TiC– Ni mixture ( , 50, and 75% are the volume fractions of nickel) affects the carbide content in the coating material obtained by cold spraying. It is shown that, when coatings are obtained from a powder mixture prepared in a V-shaped mixer, the titanium carbide content is lower than in coatings obtained from powders mechanically processed in a high-energy planetary mill. In the case where the powder mixture is mixed in a V-shaped mixer, fine titanium carbide particles do not reach the substrate surface during spraying because they are decelerated in a shock-compressed gas layer when a supersonic jet flows on an obstacle. Thus, these particles do not participate in the formation of the coating. Spraying a mechanically treated powder consisting of composite agglomerated TiC–Ni particles allows for a significant (approximately 1.8-fold) increase in the carbide content in the coating. [ABSTRACT FROM AUTHOR]

For the first time, the efficiency of thermal neutron absorption by composite coatings deposited by cold gas-dynamic spraying from mechanically activated mixtures of Al + B4C and Al + B powders on the surface of stainless steel samples has been compared with a reference standard. The comparison with the standard, which was boron steel plates, showed that the resulting coatings are somewhat inferior in terms of neutron absorption efficiency. To estimate the required thickness of the coatings, an approach based on the processing of the experimental data obtained is proposed that, in particular, takes into account the dependence of the absorption cross section on the distance traveled by the neutron flux. As well, the analysis has shown that the existing undulation (periodic inconstancy of the thickness) of the coating has virtually no effect on its protective properties (namely, on its neutron absorption coefficient). [ABSTRACT FROM AUTHOR]