# Comprehensive Study of the Mechanical and Tribological Properties of NiCr-Al Detonation Coatings
## 1 Introduction  
NiCr-Al-based coatings are widely used in devices such as gas turbines, valves, and heat generation systems in the energy sector due to their high-temperature resistance [1, 2, 3]. In such environments, NiCr-Al coatings are subjected to erosion and frictional wear caused by solid particles and high-velocity gas flows during operation. Under these aggressive conditions, the structural stability and wear resistance of NiCr-Al coatings play a critical role. Numerous studies have been carried out on the mechanical and tribological properties of NiCr-Al-based coatings [4, 5, 6]. For example, in one study by [PERSON] and [PERSON] [7], it was found that Ni-rich amorphous structures and Ni\({}_{3}\)Al crystallites formed in laser-clad NiCr-Al coatings on aluminum alloys. Furthermore, the influence of the amorphous structureon tribological performance was investigated, and it was demonstrated to significantly enhance wear resistance. The study revealed that increasing the amorphous fraction from 2.18% to 31.1% resulted in a nearly 3.6-fold reduction in wear volume. In another investigation, [PERSON] et al. [8] investigated the microstructure, friction coefficient, and wear rate of Ni-7 Cr and Ni-7 Cr-2 Al nanocomposite coatings. The results of the study showed that the significant improvement in the microhardness and wear resistance of the coating due to Al nanoparticles was attributed to the formation of amorphous oxides on the surface and the dispersion strengthening effect of Al\({}_{2}\)O\({}_{3}\) nanoparticles. Additionally, [PERSON] et al. [9] conducted electrochemical tests on NiCr-Al coatings and found that the coatings exhibited high corrosion resistance. Therefore, a comprehensive understanding of the phase structure, as well as the high-temperature, mechanical and tribological properties of NiCr-Al coatings, is essential for expanding their potential applications in demanding service environments. Currently, various deposition methods are used to produce NiCr-Al coatings. In the works of [PERSON] and [PERSON] [10; 11], Cr-Al nanoparticles were first embedded onto the surface by electrophoretic deposition (EPD), resulting in the formation of a porous layer. Subsequently, an Ni layer was introduced into this porous structure using the electrodeposition method. As a result, a uniform, dense, and oxidation-resistant NiCr-Al nanocomposite coating was obtained. These coatings were able to form an aluminum oxide (Al\({}_{2}\)O\({}_{3}\)) layer in air at 1000 \({}^{\circ}\)C, and their oxidation resistance improved depending on the Cr and Al content in the coating. In another study, [PERSON] et al. [12] produced Ni-16 Cr-14 Al nanocomposite coatings by combining electrophoretic deposition (EPD) and electrodeposition methods. Subsequently, the coatings were tested for oxidation resistance at 800 \({}^{\circ}\)C in humid air containing 10% H\({}_{2}\)O. According to the research results, a two-layer oxide scale consisting of an outer NiAl\({}_{2}\)O\({}_{4}\) layer and an inner \(\alpha\)-Al\({}_{2}\)O\({}_{3}\) layer was formed on the coating surface. The NiCr-Al coating significantly improved the oxidation resistance of steel in humid air [12]. One of the most promising and rapidly developing approaches in recent years for producing NiCr-Al-based coatings is the thermal spraying technology. In particular, high-velocity oxy-fuel (HVOF) spraying, plasma spraying, and detonation spraying methods are widely used for the deposition of NiCr-Al-based coatings. NiCr-Al coatings produced by the HVOF method are characterized by high density, structural homogeneity, and excellent mechanical strength. [PERSON] et al. [13; 14; 15] investigated the hot corrosion resistance of NiCr-Al coatings produced by the HVOF method in the low-temperature superheater zone (approximately 700 \({}^{\circ}\)C) of a coal-fired boiler. The results showed that the NiCr-Al coating formed a dense and stable oxide layer, acting as a reliable barrier against hot corrosion. [PERSON] et al.