# Comprehensive Study of the Mechanical and Tribological Properties of NiCr-Al Detonation Coatings
## 1 Introduction
[16] conducted a comprehensive study on the high-temperature corrosion resistance of NiCr-Al coatings produced by thermal spraying methods such as atmospheric plasma spraying (APS) and high-velocity oxy-fuel (HVOF). In the study by [PERSON] et al., the corrosion resistance of NiCr-Al coatings obtained by APS was evaluated as moderate [17]. [PERSON] et al. [18] used the detonation spraying method to fabricate functionally graded multilayer TBC for gas turbines. In this approach, both the Yttria-Stabilized Zirconia (YSZ) ceramic layer and the bond coat were deposited by detonation spraying, while the top nanocomposite oxide layer was applied using the slip casting (SC) method. The results of thermal resistance testing at 1200 \({}^{\circ}\)C showed that the detonation-sprayed TBC exhibited good adhesion and compatibility between all coating layers, with no signs of delamination or cracking. Over the past two decades, various techniques for synthesizing NiCr-Al-based coatings have been developed, alongside in-depth investigations into their structural properties. Among the explored methods, gradient coatings (GCs) have gained attention as a highly promising approach [19; 20; 21; 22]. Functionally graded coatings (FGCs) allow for a gradual transition in composition and properties through the coating thickness, enhancing thermal stability, mechanical strength, and resistance to wear and corrosion [23; 24; 25]. One of the key challenges in traditional homogeneous coatings is the accumulation of thermal and residual stresses during service, which FGCs are particularly well-suited to mitigate [26; 27]. Their ability to tailor material properties across the cross-section makes them a practical solution for demanding operational conditions [28; 29]. The aerospace industry has especially benefited from FGCs, where they contribute to improved component lifespan, enhanced material performance, and reduced maintenance needs [30]. For example, NiCrAlY and 8 YSZ gradient coatings applied to Inconel 718 substrates via atmospheric plasma spraying (APS) have demonstrated improvements in thermal performance [31]. Furthermore, [PERSON] et al. [32] examined how different deposition strategies--thermal oxidation, laser texturing, and their combination--affect the mechanical and tribological properties of titanium dioxide-based gradient coatings on Ti-6 Al-4V alloys. Their study found that the hybrid approach produced coatings with significantly enhanced hardness and elasticity, reducing wear by up to 95%, thereby demonstrating the effectiveness of graded architectures in high-performance applications. One of the emerging and promising technologies for producing gradient coatings (GCs) is the detonation spraying method [18; 33; 34; 35]. In this context, we conducted a study in collaboration with our co-authors, focusing on the fabrication of GC using this technique [36; 37; 38; 39; 40]. A gradient coating based on the NiCr-Al system was successfully produced via detonation spraying [41], and the process is protected by a utility model patent [42]. The obtained GC NiCr-Al coating was evaluated for high-temperature oxidation resistance, and the results demonstrated superior protective performance compared to its homogeneous counterpart (HC NiCr-Al) [43]. This study aims to evaluate the feasibility and advantages of gradient NiCr-Al coatings by comparing their mechanical properties with those of homogeneous coatings, thereby elucidating the influence of coating architecture.