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Composite aluminum matrix coatings with different content (0-72 vol.%) and size (17 and 75 µm) of B4C in the feedstock were deposited using the cold spray method. The analysis of the microstructure of the coatings was carried out using an SEM and XRD. The microhardness and adhesion strength of the sprayed coatings were measured, and sliding wear tests were carried out. It was shown that the same content in the feedstock, the larger carbide powder corresponds to its higher content in the coating. With the same boron carbide content in the coating, higher microhardness values correspond to coatings obtained from mixtures with fine carbide powder. Coatings sprayed from two different boron carbide powders at the same content in the powder correspond to approximately the same values of adhesion strength. For composite coatings with coarse ceramic powder, the volume loss decreases by about 2–3 times as compared with an aluminum coating. For coatings with fine powder, this effect is less pronounced. The presence of a fine ceramic powder in the coating has practically no effect on coefficients of friction, which turn out to be very close to the values for a coating of pure aluminum. The presence of coarse ceramic powder in the coating, regardless of its content, leads to a noticeable decrease in coefficients of friction. [ABSTRACT FROM AUTHOR]

The work is devoted to the experimental study of the effect of the B4C particles content on the microhardness and sliding wear behavior of a composite aluminum matrix coating produced by cold spray method. Using the technique of spraying mechanical powder mixtures, composite aluminum matrix coatings with boron carbide content of 3 – 17 vol.% were obtained. The coatings were examined by optical and scanning electron microscopy, X-ray diffraction analysis, and optical profilometry. The introduction of 17 vol.% boron carbide made it possible to increase the microhardness of the aluminum coating by approximately 1.5 times (up to 72.4 HV0.3). It was shown that the addition of carbide particles in the content range under consideration has practically no effect on the volume loss of the coating material during sliding wear. The results of measuring the coefficient of friction showed that with an increase in the test distance, the friction coefficient first decreases, while coatings with a higher content of the ceramic component correspond to lower friction coefficients. With a further increase in the test distance, the coefficient of friction increases, while the influence of the ceramic component on the coefficient is minimized. [ABSTRACT FROM AUTHOR]

An experimental study of the effect of mechanical milling of bronze CuAl10Fe3Mn2 and stainless steel 316L powders in a planetary mill on the process of cold sprayed coatings and their properties has been carried out. It is shown that mechanical milling of powders in a planetary mill significantly changes the size, shape, and internal structure of particles, which leads to a change in the microhardness of the material. The listed changes in the properties and characteristics used in the spraying of particles have a direct effect on both the spraying process and the properties of cold sprayed coatings. The studies performed made it possible to determine the trends of changes in the structure of coatings depending on the size, shape and internal structure of particles. [ABSTRACT FROM AUTHOR]

The article presents an investigation of gas flow that occurs under typical for cold spraying conditions when supersonic gas jet, that exhausts from De Laval nozzle, and impinges on mask with a round perforation, behind that substrate is placed. Numerical simulation was made using software ANSYS Fluent. Shadowgraph was used to obtain images of gas flow. The results obtained were analyzed and compared. [ABSTRACT FROM AUTHOR]