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The goal of this study is to develop an efficient machine learning framework for designing high-hardness multi-metal nitride coatings, overcoming the limitations of traditional trial-and-error methods. The development of multicomponent metal nitride hard coatings via multi-arc ion plating remains a significant challenge due to the vast compositional search space. Although theoretical studies in macroscopic, mesoscopic, and microscopic domains exist, these often focus on idealized models and lack effective coupling across scales, leading to time-consuming and labor-intensive traditional methods. With advancements in materials genomics and data mining, machine learning has become a powerful tool in material discovery. In this work, we construct a compositional search space for multicomponent nitrides based on electronic configuration, valence electron count, electronegativity, and oxidation states of metal elements in unary nitrides. The search space is further constrained by FCC crystal structure and hardness theory. By incorporating a feature library with micro-, meso-, and macro-structural characteristics and using clustering analysis with theoretical intermediate variables, the model enriches dataset information and enhances predictive accuracy by reducing experimental errors. This model is successfully applied to design multicomponent metal nitride coatings using a literature-derived database of 233 entries. Experimental validation confirms the model’s predictions, and clustering is used to minimize experimental and data errors, yielding a strong agreement between predicted optimal molar ratios of metal elements and nitrogen and measured hardness performance. Of the 100 Vickers hardness (HV) predictions made by the model using input features like molar ratios of metal elements (e.g., Ti, Al, Cr, Zr) and atomic size mismatch, 82 exceeded the dataset’s maximum hardness, with the best sample achieving a prediction accuracy of 91.6% validated against experimental measurements. This approach offers a robust strategy for designing high-performance coatings with optimized hardness.

Aiming at the goal of preparing high-quality coatings, this paper reviews the progress on circular arc source structure and magnetic field arc controlling technology in arc ion plating (AIP), with a focus on design characteristics of the different structures and configuration optimization of the corresponding magnetic fields. The circular arc source, due to its simple structure, convenient installation, flexible target combination, high cooling efficiency, and high ionization rate and deposition rate, has shown significant application potential in AIP technology. In terms of magnetic field arc controlling technology, this paper delves into the design progress of various magnetic field configurations, including fixed magnetic fields generated by permanent magnets, dynamic rotating magnetic fields, axially symmetric magnetic fields, rotating transverse magnetic fields, and multi-mode alternating electromagnetic coupling fields. By designing the magnetic field distribution reasonably, the trajectory and velocity of the arc spot can be controlled precisely, thus reducing the generation of macroparticles, improving target utilization, and enhancing coating uniformity. In particular, the introduction of multi-mode magnetic field coupling technology has broken through the limitations of traditional single magnetic field structures, achieving comprehensive optimization of arc spot motion and plasma transport. Hopefully, these research advances provide an important theoretical basis and technical support for the application of AIP technology in the preparation for high-quality decorative and functional coatings.

TiN coatings have been widely employed in cutting tools due to their high hardness and excellent wear resistance. While most research on nitride coatings has focused on binary (e.g., TiN) and ternary (e.g., TiAlN, TiSiN) systems, the quaternary TiMoSiN system remains comparatively underexplored. In response to the growing demand for comprehensive coating performance under increasingly complex working conditions, this work incorporates Mo and Si into the TiN system to synergistically enhance mechanical, tribological, and corrosion-resistant properties. TiMoSiN coatings were deposited onto cemented carbide substrates by arc ion plating using a Ti0.8Mo0.1Si0.1 alloy target. The influence of nitrogen partial pressure (0.2–1.7 Pa) on the microstructure, mechanical properties, tribological behavior, and electrochemical corrosion performance was investigated. The results show that nitrogen partial pressure plays a critical role in regulating the chemical composition, phase structure, and preferred orientation of the coatings. As the nitrogen partial pressure increases, surface macroparticles are reduced, while the Ti and Mo contents decrease and the Si and N contents increase. The phase structure evolves from a dual-phase mixture of TiN and Ti2N to a single TiN phase, accompanied by a shift in preferred orientation from (111) to (200). The hardness of the coatings ranges from 36.2 to 43.1 GPa, reaching a maximum of 43.1 GPa at 1.0 Pa. The coating deposited at 0.6 Pa exhibits the best overall performance: it achieves the lowest friction coefficient (0.349) and wear rate (1.08 × 10−7 mm3/(N·m)), together with the highest corrosion resistance, as reflected by the most noble corrosion potential (−152 mV) and the lowest corrosion current density (8.99 × 10−8 A·cm−2). This study demonstrates that nitrogen partial pressure effectively controls the microstructure and multifunctional properties of TiMoSiN coatings, providing practical process guidelines for their application in demanding cutting environments.

Aqueous zinc-ion batteries (ZIBS) are becoming more popular as the use of energy storage devices grows, owing to advantages such as safety and an abundant zinc supply. In this study, molybdenum powder was loaded directly on carbon fiber cloth (CFC) via multi-arc ion plating to obtain Mo@CFC, which was then oxidatively heated in a muffle furnace for 20 min at 600 °C to produce high mass loading α-MoO3@CFC (α-MoO3 of 12–15 mg cm−2). The cells were assembled with α-MoO3@CFC as the cathode and showed an outstanding Zn2+ storage capacity of 200.8 mAh g−1 at 200 mA g−1 current density. The capacity retention rate was 92.4 % after 100 cycles, along with an excellent cycling performance of 109.8 mAh g−1 following 500 cycles at 1000 mA g−1 current density. Subsequently, it was shown that CFC-loaded α-MoO3 cathode material possessed significantly improved electrochemical performance when compared to a cell constructed from commercial MoO3 using conventional slurry-based electrode methods. This work presents a novel yet simple method for preparing highly loaded and binder-free cathodic materials for aqueous ZIBs. The results suggest that the highly loaded cathode material with a high charge density may be potentially employed for future flexible device assembly and applications.

TC4 titanium alloy was treated by micro-arc oxidation (MAO) technology, and then CrN coating was prepared on the surface of MAO coating by multi-arc ion plating (MAIP) technology to form MAO/CrN composite film, so as to improve the tribological properties of TC4. The microstructure and phase composition of the film were detected and analyzed by scanning electron microscopy (SEM) and x-ray diffraction (XRD). The surface roughness, bonding strength and tribological properties of the film were evaluated by using a roughness tester, an automatic scratch tester for coating adhesion, a multi-functional friction and wear tester and a three-dimensional ultra-depth-of-field microscope system. The results show that the tribological properties of TC4 are improved after micro-arc oxidation treatment. The friction coefficient of TC4 is about 0.6, the friction coefficient of TC4/MAO is about 0.5, and the friction coefficient of TC4/MAO/CrN is about 0.2. The surface roughness of TC4/MAO/CrN is only 1.4 μm. The composite layer exhibits excellent tribological properties. The wear mechanism of TC4, TC4/MAO coating and TC4/MAO/CrN coating is abrasive wear.

Multi-principal element nitrides have great application potential in protective coatings. However, the investigation of the oxidation and corrosion resistance of multi-principal element nitride coatings is still insufficient. The synthesis and high-temperature performance of AlCrNbSiTiN multi-principal element nitride coatings fabricated through optimized arc ion plating (AIP) were explored. Leveraging the high ionization efficiency and ion kinetic energy characteristic of AIP, coatings with significantly fewer internal defects were obtained. These coatings demonstrate superior mechanical properties, including a maximum hardness of 36.5 GPa and critical crack propagation resistance (CPR) values approaching 2000 N2. Optimal coatings exhibited exceptional water vapor corrosion resistance (5.15 at% O after 200 h). The coatings prepared at −150 V had the optimal corrosion resistance, with the coating resistance and corrosion current density being 1.68 × 104 Ω·cm2 and 0.79 μA·cm−2, respectively. AlCrNbSiTiN coatings produced under these optimized AIP conditions exhibit remarkably high-temperature oxidation, highlighting their potential for use in demanding engineering applications.

Hard coatings, such as transition metal nitrides, have been widely applied to improve the mechanical properties and tribological performance of cutting tools. The coatings in various multilayered or gradient structures have been designed to meet the demands of more severe service environments and more precise processing requirements. In this work, TiN/TiSiN coatings in several gradient and multilayered structures were deposited on cemented carbides by cathodic arc ion plating using Ti and TiSi alloy targets. The modulation period (Λ) of the multilayer gradually varies with thickness, ranging from 6 to 46 nm. The gradient multilayer coatings consist of a nanocrystalline-amorphous composite with compact growth. The coating with a modulation period first increasing and then decreasing has the highest hardness of 38 GPa, and the maximum residual compressive stress of −2.71 GPa, as well as the minimum coefficient of friction (COF) and wear rate. Gradient and multilayer structures moderate the brittleness caused by the presence of amorphous SiNx phase and optimize the mechanical properties and tribological performances of the coatings.

Cr coatings with a thickness of about 19 μm were synthesized on Zr-4 cladding using plasma-enhanced arc ion plating. A Zr-Cr micro-diffusion layer was formed via Cr ion cleaning before deposition to enhance the interface bonding strength. Cr coatings exhibit an obvious columnar crystal structure with an average grain size of 1.26 μm using SEM (scanning electron microscopy) and EBSD (electron backscatter diffraction) with a small amount of nanoscale pores on the surface. A long-term aqueous test at 420 ± 3 °C, 10.3 ± 0.7 MPa and isothermal oxidation tests at 900~1300 °C in air were conducted to evaluate the Cr-coated Zr-4 cladding. All the results showed that the Cr coatings had a significant protective effect to the Zr-4 alloy. However, the corrosion deterioration mechanism is different. A gradual thinning of the Cr coating was observed in a long-term aqueous test, but a cyclic corrosion mechanism of void initiation–propagation–cracking at the oxide film interface is the main corrosion characteristic of the Cr coating in isothermal oxidation. Different corrosion models are constructed to explain the corrosion mechanism.

Cr-coated Zr alloys are widely considered the most promising accident-tolerant fuel (ATF) cladding materials for engineering applications in the near term. In this work, Cr coatings were prepared on the surfaces of 1400 mm long N36 cladding tubes using an industrial multiple arc source system. Orthogonal analyses were conducted to demonstrate the significance level of various process parameters influencing the characteristics of coatings (surface roughness, defects, crystal orientation, grain structure, etc.). The results show that the arc current mainly affects the coating deposition rate and the droplet particles on the surface or inside the coatings; however, the crystal preferred orientation and grain structure are more significantly influenced by the gas pressure and negative bias voltage, respectively. Then, the underlying mechanisms are carefully discussed. At last, a set of systemic methods to control the quality and microstructures of Cr coatings are summarized.

CrAlN coatings are widely used for surface protection because of their excellent properties. Alloying with additional elements has been shown to effectively modify mechanical and tribological behavior of these coatings. In this study, CrAlMoxN coatings (x = 0–18.83 at%) were prepared by an arc ion plating technology, corresponding to CrAlN and Mo-doped variants CrAlMoN-1, CrAlMoN-2 and CrAlMoN-3, respectively). The effects of Mo incorporation on the microstructure, mechanical properties, and friction-wear performance at both room and high temperature were systematically investigated. Results indicate that Mo dissolves into the CrAlN lattice to form a solid-solution structure, which induces lattice expansion as confirmed by the shift of XRD peaks toward lower angles. Furthermore, a moderate addition of Mo substantially improves the hardness, toughness, and crack propagation resistance of the coatings. All four coatings exhibit friction coefficients of approximately 0.5 at room temperature. However, at 600 °C, the CrAlMoN-2 coating demonstrates a much more stable friction coefficient curve and achieves the lowest average friction coefficient of 0.75, together with a wear rate of 3.94 × 10−6 mm3/N·m, indicating greatly improved high-temperature tribological performance.