Obtaining coatings by complex NiAl-based anodic alloys

S.N. Khimukhin, K.P. Eremina, V.K. Khe show affiliations and emails
Received 31 January 2024; Accepted 17 April 2024;
Citation: S.N. Khimukhin, K.P. Eremina, V.K. Khe. Obtaining coatings by complex NiAl-based anodic alloys. Lett. Mater., 2024, 14(2) 161-166
BibTex   https://doi.org/10.48612/letters/2024-2-161-166

Abstract

Some areas consisting of two layers free of microcracks have been found in the structure of the coatings (Fig. 1). The lower layer - points (3 – 5) contains an increased concentration of Fe (~ 17-47 at.%). The (Fe) concentration in the crystallites of the upper layer (points 6 – 9) does not exceed 5 at.%, which is adequate to its content in crystallites in the areas with microcracks (Fig. 2). The lower layer of a two-layer coating due to its higher ductility acts as a barrier preventing the occurrence of microcracks at a sufficiently high Fe content (more than 14 wt.%).Complex-alloyed (Cr, Si, Fe, Zr, Mo) anodic alloys based on NiAl smelted by liquid-phase self-propagating high-temperature synthesis (SHS) from oxides (NiO, Cr2O3, MoO3) and baddeleyite−zirconium mineral concentrate, were used to produce coatings on steel 45 (cathode) by electrospark deposition method (ESD). The influence of different concentrations of Mo (0.6 – 7.8 wt.%) in the composition of anodic alloys and different impulse energy of electric spark (E1= 0.312 and E2 = 0.72 J) on the abrasive wear resistance of coatings was studied. Maximum increase in wear resistance (5 times) was achieved when coatings were formed by electric spark pulses with energy E2 and complex alloyed anodic alloys containing 3.5 wt.% Mo were used. Microstructure of the coatings is represented by columnar crystallites normally oriented with respect to the cathode surface and relatively regularly located transverse microcracks. Separate areas were found in the coatings that had a two-layer structure and were free of microcracks. It has been established that the formation of microcracks is prevented by the lower (relative to the cathode) layer, which has an increased Fe content in the crystallites (17 or more at.%), in contrast to the usual content — up to 5 at.%.

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Funding

1. Ministry of Science and Higher Education of the Russian Federation - 075-01108-23-02