CrAgCeN composite coating and preparation method and application thereof

Abstract

The application provides a CrAgCeN composite coating and a preparation method and application thereof, and belongs to the field of coatings. The CrAgCeN composite coating comprises: a Ce-Ti transition layer covering the surface of a substrate; and a CrAgCeN film layer covering the surface of the Ce-Ti transition layer; wherein the CrAgCeN film layer is composed of the following chemical components: Ce: 1.0%-3.0%, Ag: 1.5%-3.0%, Cr: 45.0%-50.0%, N: 35.0%-40.0%, and the balance is inevitable impurities. The composite coating of the application realizes the synergistic optimization of high hardness, high bonding force and low friction coefficient through the fine-grain strengthening of rare earth Ce and the synergistic lubrication effect of Ag / CeO2, and has excellent wide-temperature-range tribological stability and high-temperature oxidation resistance, and can be used for the surface wear-resistant protection of aero-engine bearings, mechanical sealing elements and high-temperature sliding parts.

Description

Technical Field

[0001] This application relates to the field of coating technology, and in particular to a CrAgCeN composite coating, its preparation method, and its application. Background Technology

[0002] CrN coatings possess high hardness, toughness, good oxidation resistance, and wear resistance, making them widely used as protective coatings for cutting tools, molds, and mechanical parts. To further enhance the overall performance of CrN coatings, researchers have attempted to prepare multi-element ceramic-based composite coatings by adding metallic elements such as Ag and Cu to the CrN matrix. Ag, with its low shear strength and stable thermochemical properties, can act as a solid lubricant during friction. Therefore, CrN / Ag composite coatings can effectively reduce the coefficient of friction and hold promise for application in atmospheric environments and vacuum conditions over a wide temperature range. For example, existing technologies disclose methods for preparing CrN / Ag composite coatings using magnetron sputtering, where the Ag content in the coating is controlled by adjusting the Ag target current, resulting in a coating that combines wear resistance and lubrication. Furthermore, recent studies have reported on further doping the CrN / Ag system with the rare earth element Ce, creating CrAgCeN coatings, and have preliminarily explored the influence of process parameters such as the nitrogen-argon flow ratio and deposition pressure on the tribological properties of the coating.

[0003] However, the aforementioned existing technologies still have the following drawbacks: On the one hand, while Ag, as a soft solid lubricating phase, reduces the coefficient of friction, it also causes a significant decrease in the hardness of the composite coating. Furthermore, the Ag phase is rapidly consumed during friction, resulting in insufficient wear life of the coating and making it difficult to meet long-term service requirements. On the other hand, existing research on CrAgCeN coatings only focuses on the influence of single process parameters on performance, without addressing the technical means to systematically resolve the lubrication-strengthening contradiction. Simultaneously, for high-temperature friction lubrication problems, temperature-sensitive zones still exist, especially with significant performance fluctuations in coatings under wide temperature range conditions, making it difficult to meet the comprehensive requirements of high hardness, high adhesion, low coefficient of friction, and wide temperature range stability for coatings under extreme conditions such as aero-engine bearings. Summary of the Invention

[0004] This application provides a CrAgCeN composite coating, its preparation method, and its application, which overcomes the defects of reduced coating hardness and insufficient wear life caused by Ag elements while maintaining the good lubrication performance of CrN / Ag coating. It achieves synergistic optimization of high coating hardness, high adhesion, and low friction coefficient, and improves the tribological stability and high-temperature oxidation resistance of the coating over a wide temperature range.

[0005] In a first aspect, this application provides a CrAgCeN composite coating, the CrAgCeN composite coating comprising: Ce-Ti transition layer covering the substrate surface; A CrAgCeN thin film layer covering the surface of the Ce-Ti transition layer; The CrAgCeN thin film layer, by mass fraction, is composed of the following chemical components: Ce: 1.0%–3.0%, Ag: 1.5%–3.0%, Cr: 45.0%–50.0%, N: 35.0%–40.0%, with the balance being unavoidable impurities.

[0006] Optionally, the Ce-Ti transition layer is composed of the following chemical composition by mass fraction: Ce: 5.0% to 15.0%, Ti: 75.0% to 95.0%, with the balance being unavoidable impurities.

[0007] Optionally, the thickness of the CrAgCeN thin film layer is 1.2–2 μm, and the thickness of the Ce-Ti transition layer is 100–200 nm.

[0008] Optionally, the CrAgCeN composite coating has the following properties: hardness of 12.0 to 16.5 GPa, film-substrate adhesion of 50.0 to 70.0 N, and average coefficient of friction of 0.35 to 0.55.

[0009] Secondly, this application provides a method for preparing the CrAgCeN composite coating according to any one of the first aspects, the method comprising the following steps: S1. The substrate is ultrasonically cleaned to obtain a pretreated substrate; S2. The pretreated substrate is placed into a vacuum chamber and evacuated to a vacuum level of 5 × 10⁻⁶. -4 Pa, argon gas is introduced, the working pressure is controlled at 0.3-0.8 Pa, and the substrate is heated to 180-220℃; S3. Sputtering is performed using a Ce-Ti alloy target at a working pressure of 0.3 to 0.8 Pa, with a sputtering power of 40 to 100 W and a sputtering time of 10 to 30 min. No substrate bias is applied to form a Ce-Ti transition layer on the substrate surface. S4. Keep argon gas flowing in and simultaneously introduce nitrogen gas at a flow rate of 20–50 sccm. Use a Cr target and a Ce-Ag alloy target for co-sputtering. The sputtering power of the Cr target is 180–230 W, the working pressure is 0.3–0.8 Pa, and the sputtering time is 100–150 min. Do not apply a substrate bias voltage to form a CrAgCeN thin film layer on the surface of the Ce-Ti transition layer, and allow it to cool naturally.

[0010] Optionally, in step S1, the ultrasonic cleaning is performed by sequentially cleaning with anhydrous ethanol and then with high-purity acetone; the substrate is a steel substrate or a single-crystal silicon substrate.

[0011] Optionally, in step S2, the flow rate of the argon gas is 15–60 sccm.

[0012] Optionally, in step S3, the Ce-Ti alloy target has a purity of 99.99% and is composed of Ce and Ti in a mass ratio of 10:90.

[0013] Optionally, in step S4, the Ce-Ag alloy target has a purity of 99.99%, is composed of Ce and Ag in a mass ratio of 50:50, and has a sputtering power of 50 to 90 W.

[0014] Thirdly, this application provides the application of the CrAgCeN composite coating described in any one of the first aspects in the preparation of wear-resistant coatings on the surfaces of aero-engine bearings, mechanical seals, or high-temperature sliding components.

[0015] The technical solutions provided in this application have the following advantages compared with the prior art: This application utilizes a technical approach of hard phase reinforcement, multiphase synergistic lubrication, and gradient interface optimization to systematically achieve synergistic optimization of high hardness, high bonding force, and low friction coefficient, as well as improved tribological stability over a wide temperature range and high-temperature oxidation resistance, without compromising the performance of a single element.

[0016] The high hardness is achieved through the synergistic effect of the CrN hard phase and the grain refinement strengthening of rare earth Ce. CrN, as the main framework of the coating, provides intrinsic high hardness and good toughness. Based on this, the appropriate amount of rare earth Ce is incorporated, utilizing its larger atomic radius to induce lattice distortion, while simultaneously increasing the nucleation rate of the CrN phase and refining the grain size, resulting in a denser coating structure and a grain refinement strengthening effect. More importantly, this application precisely controls the Ce content in the film within a window range of 1.0% to 3.0%, fully leveraging the grain refinement strengthening effect of rare earth while effectively avoiding the increase in internal stress and instability of the crystal structure caused by excessive rare earth, thus achieving a balance between increased hardness and structural stability.

[0017] The high adhesion is attributed to the gradient buffer design of the Ce-Ti transition layer and the synergistic effect of the process without applying substrate bias. The Ce-Ti alloy transition layer (Ce:Ti=10:90) forms an intermediate medium with a gradual change in composition between the substrate and the CrAgCeN film layer: Ti has good affinity with the steel substrate, forming a strong interfacial bond; the introduction of Ce further refines the grain size of the transition layer, enabling a gradient transition in lattice structure and thermal expansion coefficient between the transition layer and the top CrAgCeN film, effectively alleviating interfacial stress concentration. Simultaneously, the absence of substrate bias during the entire sputtering deposition process avoids excessive bombardment damage to the substrate and the deposited film by high-energy particles, reducing stress accumulation within the coating and thus ensuring the integrity of the transition layer interface and the stability of the film-substrate adhesion.

[0018] The achievement of a low coefficient of friction relies on the cross-temperature-range synergistic lubrication mechanism of Ag and CeO2. In the room to medium-temperature range, Ag, as a solid lubricating phase, exerts its friction-reducing effect due to its low shear strength. In the high-temperature range, Ce, under the influence of frictional heat, in-situ generates a CeO2 lubricating phase with friction-reducing and wear-resistant properties, complementing Ag. This allows the coating to maintain effective lubrication across different temperature ranges, avoiding the problem of a sharp drop in lubrication function after the Ag phase is depleted in traditional CrN / Ag coatings. More importantly, precise control of the Ce content window ensures that the amount of CeO2 generated during friction is moderate, sufficient to form a continuous lubricating film without inducing abrasive wear due to excessive oxide accumulation.

[0019] The improved tribological stability and high-temperature oxidation resistance over a wide temperature range stem from the synergistic effect of the aforementioned multiple mechanisms and the overall optimization of the coating structure. On one hand, the CrN phase in the CrAgCeN film exhibits excellent thermal stability below 500℃, without phase transformation or significant release of nitrogen, ensuring the coating's sustained mechanical properties at high temperatures. On the other hand, the addition of Ce reduces the oxidation rate of the coating, promoting the formation of a dense oxide layer at high temperatures and effectively preventing oxygen diffusion inwards. Simultaneously, the complementary lubrication of Ag and CeO2 across temperature ranges ensures a smooth transition of the friction coefficient over a wide temperature range from room temperature to 500℃, avoiding the abrupt performance changes of traditional coatings in specific temperature zones. Furthermore, the stress buffering effect of the Ce-Ti transition layer ensures that the coating will not fail prematurely due to thermal cycling stress during service across the aforementioned wide temperature range, thus comprehensively improving the coating's service life and reliability.

[0020] In summary, this application achieves an organic whole by precisely controlling the composition (especially the window effect of Ce content), designing the gradient structure of the layers (Ce-Ti transition layer), and synergistically optimizing the process (no substrate bias applied, matching co-sponging parameters). This results in the CrN hard skeleton, Ag solid lubricating phase, and CeO2 high-temperature lubricating phase forming a cohesive whole. In the core contradiction of lubrication and strengthening, a synergistic gain effect is achieved where each complements the other rather than weakens it. Thus, the comprehensive performance requirements of high hardness, high bonding strength, and low friction coefficient are simultaneously met over a wide temperature range. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a surface SEM image of the CrAgCeN composite coating provided in Example 1 of this application; Figure 2 This is a surface SEM image of the CrAgCeN composite coating provided in Embodiment 2 of this application; Figure 3 This is a surface SEM image of the CrAgCeN composite coating provided in Example 3 of this application; Figure 4 The wear track morphology of the CrAgCeN composite coating provided in Example 1 of this application; Figure 5 This is a wear track morphology image of the CrAgCeN composite coating provided in Example 2 of this application; Figure 6 The wear track morphology of the CrAgCeN composite coating provided in Example 3 of this application; Figure 7 The friction coefficient curves of the CrAgCeN composite coatings provided in Examples 1-3 of this application are shown. Figure 8 The wear track morphology of the CrAgCeN composite coating provided in Comparative Example 2 of this application; Figure 9 XRD patterns of the CrAgCeN composite coating provided in Example 2 of this application at different temperatures; Figure 10 This is an EDS energy dispersive spectroscopy (EDS) analysis diagram of the CrAgCeN composite coating provided in Example 2 of this application; Figure 11 The appearance morphology of the CrAgCeN composite coating provided in Example 2 of this application after a friction test at 300°C; Figure 12 The image shows the appearance of the CrAgCeN composite coating provided in Example 2 of this application after a friction test at 500°C. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0026] This application provides a CrAgCeN composite coating, the CrAgCeN composite coating comprising: Ce-Ti transition layer covering the substrate surface; A CrAgCeN thin film layer covering the surface of the Ce-Ti transition layer; The CrAgCeN thin film layer, by mass fraction, is composed of the following chemical components: Ce: 1.0%–3.0%, Ag: 1.5%–3.0%, Cr: 45.0%–50.0%, N: 35.0%–40.0%, with the balance being unavoidable impurities.

[0027] In some embodiments, the Ce-Ti transition layer is composed of the following chemical composition by mass fraction: Ce: 5.0% to 15.0%, Ti: 75.0% to 95.0%, with the balance being unavoidable impurities.

[0028] It should be noted that in the Ce-Ti transition layer, the Ce content is 5.0%–15.0%, and the Ti content is 75.0%–95.0%. The main function of this transition layer is to alleviate the difference in thermal expansion coefficients between the substrate and the CrAgCeN thin film, thereby improving the film-substrate adhesion. Ti, as a commonly used transition layer metal, has good affinity with the steel substrate and can form a strong interfacial bond. The introduction of Ce further refines the grain structure of the transition layer, creating a gradient transition in composition and structure between the transition layer and the top CrAgCeN thin film, avoiding interfacial delamination caused by abrupt changes in interlayer properties. This application achieves a film-substrate adhesion of 50.0–70.0 N through the Ce-Ti transition layer, which is significantly better than that without rare earth doping.

[0029] The chemical composition of the CrAgCeN thin film layer needs to be controlled within the range of Ce: 1.0%–3.0%, Ag: 1.5%–3.0%, Cr: 45.0%–50.0%, and N: 35.0%–40.0%. The roles of each element are as follows: The Ce content (1.0%–3.0%) is a core technical parameter of this application. As a rare earth element, Ce has a large atomic radius, which can refine grain size during thin film nucleation, making the film structure more compact. Simultaneously, Ce can generate CeO2 crystalline phases with friction-reducing and wear-resistant properties in situ during friction, thus making the friction process smoother. However, a higher Ce content is not always better: when the Ce content is too low, the activity of rare earth elements cannot be fully utilized, making it difficult to effectively improve film performance; when the Ce content is too high, the internal crystalline phase structure of the film is unstable, internal stress increases, leading to peeling on the film surface, damage to the overall structure, and a significant decrease in tribological properties. This application limits the Ce content to 1.0%–3.0% (1.4%–2.8% in the preferred embodiment), within which the grain-refining and friction-reducing lubricating effects of rare earth elements can be fully utilized, while avoiding structural instability problems caused by excessive rare earth elements.

[0030] The limitation of Ag content (1.5%–3.0%) strikes a balance between lubrication and mechanical properties. Ag has low shear strength and stable thermochemical properties, and as a solid lubricating phase, it can effectively reduce the coefficient of friction of the coating. However, excessive addition of Ag will lead to a decrease in the hardness of the composite coating, and the rapid depletion of the Ag phase during friction will shorten the wear life of the coating. This application controls the Ag content at 1.5%–3.0%, ensuring good lubrication while avoiding excessive reduction of coating hardness by Ag.

[0031] Cr content (45.0%–50.0%) and N content (35.0%–40.0%) are the main components constituting the CrN hard phase. The CrN phase provides the coating with high hardness (12.0–16.5 GPa in this application) and good toughness, forming the structural basis for the coating's wear resistance. Within this ratio range, the CrN phase can fully nucleate and grow, forming a dense hard skeleton, providing matrix support for the uniform distribution of Ag and Ce.

[0032] The balance consists of unavoidable impurities, mainly including oxygen (O). Since Ce-Ag alloy targets are easily oxidized during sputtering, the presence of a small amount of oxygen is difficult to completely avoid; however, this application controls the impurity content within an acceptable range by controlling process parameters such as deposition pressure, gas flow rate, and target power, thus avoiding its adverse effects on coating performance.

[0033] In some embodiments, the thickness of the CrAgCeN thin film layer is 1.2–2 μm, and the thickness of the Ce-Ti transition layer is 100–200 nm.

[0034] The thickness of the CrAgCeN thin film (1.2–2 μm) is the result of striking a balance between ensuring the wear resistance of the coating and avoiding excessive internal stress. If the thickness is too thin (<1.2 μm), the wear resistance allowance of the coating is insufficient, and it is prone to premature wear-through failure during long-term friction service; if the thickness is too thick (>2 μm), the accumulated stress inside the coating increases, which increases the risk of peeling and reduces the stability of the film-substrate adhesion. The thickness of the Ce-Ti transition layer (100–200 nm) can effectively buffer the stress between the substrate and the thin film layer without causing a significant decrease in the overall hardness of the composite coating due to an excessively thick transition layer.

[0035] In some embodiments, the CrAgCeN composite coating has the following properties: hardness of 12.0 to 16.5 GPa, film-substrate adhesion of 50.0 to 70.0 N, and average coefficient of friction of 0.35 to 0.55.

[0036] This application achieves high hardness (12.0–16.5 GPa), high adhesion (50.0–70.0 N), and low coefficient of friction (0.35–0.55) in CrAgCeN composite coatings through the synergistic effect of hard phase reinforcement, lubricating phase regulation, and interface transition optimization.

[0037] Specifically, the increase in hardness mainly stems from two aspects: Firstly, the CrN hard phase, as the main skeleton of the coating, has high hardness and toughness, providing a mechanical basis for the wear resistance of the coating; secondly, the appropriate amount of rare earth Ce (1.0% to 3.0%) is incorporated to cause lattice distortion by utilizing its large atomic radius, which refines the CrN grains and produces a fine grain strengthening effect, making the coating more dense and further improving the hardness.

[0038] The improved film-substrate adhesion is attributed to the Ce-Ti transition layer. This transition layer is sputtered using an alloy target with a Ce:Ti ratio of 10:90, creating a gradient transition in composition and structure between the substrate and the CrAgCeN thin film. This effectively alleviates the interfacial stress caused by the difference in thermal expansion coefficients between the two layers, avoiding exfoliation failure caused by abrupt changes in interlayer structure, thereby achieving an adhesion strength of 50.0–70.0 N.

[0039] The achievement of a low coefficient of friction depends on the synergistic lubrication effect of Ag and CeO2. Ag, as a solid lubricating phase, plays a role in reducing friction during the friction process; while Ce generates CeO2 crystal phase with friction-reducing and wear-resistant properties in situ under the high temperature of friction, which works synergistically with Ag to make the friction process more stable.

[0040] In summary, the CrN hard phase provides mechanical support, the rare earth Ce simultaneously performs grain refinement and high-temperature lubrication functions, and Ag undertakes room-temperature friction reduction. These three phases complement each other within the compositional range and layer structure defined in this application, ultimately enabling the coating to possess excellent hardness, adhesion, and tribological properties. It is important to emphasize that achieving these properties depends on the precise control of the content of each element within the range defined in this application—especially the Ce content (1.0%–3.0%), which exhibits a significant window effect; too little (insufficient activity) or too much will lead to a sharp decline in overall performance.

[0041] Based on a general inventive concept, this application provides a method for preparing the CrAgCeN composite coating as described in any one of the above claims, the method comprising the following steps: S1. The substrate is ultrasonically cleaned to obtain a pretreated substrate; S2. The pretreated substrate is placed into a vacuum chamber and evacuated to a vacuum level of 5 × 10⁻⁶. -4 Pa, argon gas is introduced, the working pressure is controlled at 0.3-0.8 Pa, and the substrate is heated to 180-220℃; S3. Sputtering is performed using a Ce-Ti alloy target at a working pressure of 0.3 to 0.8 Pa, with a sputtering power of 40 to 100 W and a sputtering time of 10 to 30 min. No substrate bias is applied to form a Ce-Ti transition layer on the substrate surface. S4. Keep argon gas flowing in and simultaneously introduce nitrogen gas at a flow rate of 20–50 sccm. Use a Cr target and a Ce-Ag alloy target for co-sputtering. The sputtering power of the Cr target is 180–230 W, the working pressure is 0.3–0.8 Pa, and the sputtering time is 100–150 min. Do not apply a substrate bias voltage to form a CrAgCeN thin film layer on the surface of the Ce-Ti transition layer, and allow it to cool naturally.

[0042] In some embodiments, in step S1, the ultrasonic cleaning is performed by sequentially cleaning with anhydrous ethanol and then with high-purity acetone; the substrate is a steel substrate or a single-crystal silicon substrate.

[0043] In some embodiments, in step S2, the flow rate of the argon gas is 15–60 sccm.

[0044] In some embodiments, in step S3, the Ce-Ti alloy target has a purity of 99.99% and is composed of Ce and Ti in a mass ratio of 10:90.

[0045] In some embodiments, in step S4, the Ce-Ag alloy target has a purity of 99.99%, is composed of Ce and Ag in a mass ratio of 50:50, and has a sputtering power of 50 to 90 W.

[0046] It should be noted that the preparation method of this application adopts unbalanced magnetron sputtering technology, and the composite coating is prepared by a three-step method of substrate pretreatment → Ce-Ti transition layer sputtering → CrAgCeN co-sputtering. The functions of each step are as follows: Step S1 (ultrasonic cleaning of the substrate) is a fundamental pretreatment process to ensure coating quality. Anhydrous ethanol and high-purity acetone are used for sequential cleaning. Taking advantage of the difference in solubility and volatility between the two, organic contaminants and oil residues on the substrate surface are removed respectively, ensuring a clean substrate surface and providing good interfacial conditions for subsequent film deposition, thus avoiding a decrease in film-substrate adhesion caused by contaminants.

[0047] Step S2 (vacuum evacuation and heating) creates the necessary environmental conditions for sputter deposition. Vacuum is evacuated to 5 × 10⁻⁶. -4 The aim is to reduce the background pressure within the vacuum chamber to an extremely low level, minimizing the interference of residual gas molecules (especially water vapor and oxygen) on the sputtering process and avoiding target oxidation and coating contamination. Argon is introduced as the working gas, and the pressure is controlled at 0.3–0.8 Pa because the accelerated bombardment of the target by argon ions in an electric field is a prerequisite for sputtering deposition. This pressure range maintains stable glow discharge while ensuring that sputtered atoms have sufficient mean free path to reach the substrate surface. Heating the substrate to 180–220 °C enhances atomic migration on the substrate surface, promoting denser film growth and reducing residual stress.

[0048] Step S3 (Ce-Ti transition layer sputtering) is one of the key steps that distinguishes this application from existing CrAgCeN coating preparation technologies. A Ce-Ti alloy target (Ce:Ti=10:90) is used for sputtering for 10–30 min to form a 100–200 nm Ce-Ti transition layer on the substrate surface. This transition layer has three functions: first, Ti, as a transition metal with good affinity, forms a strong interfacial bond with the steel substrate; second, the introduction of Ce refines the grain structure of the transition layer, creating a compositional gradient between the transition layer and the top CrAgCeN film, reducing interfacial stress concentration; and third, this transition layer effectively alleviates the mismatch in thermal expansion coefficients between the substrate and the CrAgCeN film layer, thereby significantly improving the film-substrate adhesion (adhesion strength reaches 50–70 N). Sputtering power of 40–100 W is used to stably excite glow discharge in Ce-Ti target materials. Too low a power makes it difficult to ignite, while too high a power results in an excessively fast sputtering rate, leading to a loose transition layer structure. The characteristic of not applying substrate bias allows sputtered particles to deposit at lower energy, avoiding excessive bombardment damage to the substrate surface, which is beneficial for forming a dense transition layer with low internal stress.

[0049] Step S4 (CrAgCeN thin film co-sputtering) is the core step in achieving the coating's functionality. In this step, the Cr target RF power supply and the Ce-Ag alloy target power supply are simultaneously turned on, and co-sputtering is performed in a mixed atmosphere of argon and nitrogen. Argon maintains the ion source required for sputtering, while nitrogen acts as the reactive gas, combining with sputtered Cr atoms to form the CrN hard phase. A Cr target power of 180–230 W ensures sufficient deposition rate and density of the CrN phase. A Ce-Ag target power of 50–90 W controls the doping levels of Ce and Ag in the coating, placing them within the optimal ranges of 1.0%–3.0% and 1.5%–3.0%, respectively. An operating pressure of 0.3–0.8 Pa, in conjunction with step S2, provides a stable plasma environment for co-sputtering; a sputtering time of 100–150 min controls the thin film thickness to reach 1.2–2 μm. A nitrogen flow rate of 20–50 sccm is a direct means of controlling the N content in the thin film, affecting the stoichiometry and crystal quality of the CrN phase, and thus determining the hardness level of the coating. Not applying a substrate bias voltage during sputtering helps reduce internal stress in the film and avoids defects caused by high-energy particle bombardment. Natural cooling slows down the cooling rate, allowing internal stress in the coating to release gradually and preventing film cracking or interface peeling caused by rapid cooling.

[0050] Based on a general inventive concept, this application provides the application of the CrAgCeN composite coating described in any one of the above in the preparation of wear-resistant coatings on the surface of aero-engine bearings, mechanical seals or high-temperature sliding parts.

[0051] The reason why the CrAgCeN composite coating of this application can be applied to the surface wear protection of aero-engine bearings, mechanical seals and high-temperature sliding parts is that its wide temperature range self-lubricating properties are highly matched with the performance requirements under the above extreme working conditions.

[0052] Aero-engine bearings operate in extremely harsh environments, simultaneously enduring high temperatures, heavy loads, and high-speed sliding friction. While traditional CrN / Ag composite coatings offer some lubrication, the Ag phase is rapidly depleted under high temperatures, leading to a decrease in coating hardness and hindering long-term stable operation. This application addresses this issue by introducing rare-earth Ce. Firstly, it refines the CrN grains, maintaining the coating hardness between 12.0 and 16.5 GPa, ensuring a robust mechanical basis for wear resistance. Secondly, Ce generates a CeO2 lubricating phase in situ under high frictional temperatures, creating a synergistic lubrication effect with Ag. This allows the coating to maintain a low coefficient of friction (0.373 at room temperature, as low as 0.35 at 300°C) across a wide temperature range from room temperature to 500°C, with a wear rate of only 1.1 × 10⁻⁶. -6 ~5.8×10 -6 mm 3 / (N·m), which is especially suitable for the stable lubrication requirements of engine bearings within the range of operating temperature fluctuations.

[0053] Mechanical seals and high-temperature sliding components also require coatings with excellent film-substrate adhesion to prevent spalling failure under alternating stress. In this application, the Ce-Ti transition layer achieves a film-substrate adhesion of 50–70 N, while Ce doping enhances the coating's resistance to plastic deformation (H / E value ≥ 0.085), effectively suppressing fatigue spalling during long-term sliding friction. High-temperature oxidation resistance experiments further confirm that the coating does not undergo CrN phase decomposition or significant N release below 500℃, exhibiting good structural stability and meeting the stringent thermal stability requirements of high-temperature sliding components.

[0054] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0055] Example 1 This embodiment provides a CrAgCeN composite coating and its preparation method, the specific steps of which are as follows.

[0056] S1. The substrate is sequentially cleaned with anhydrous ethanol for 20 min and high-purity acetone for 15 min to obtain the pretreated substrate.

[0057] S2. Load the pretreated matrix into the vacuum chamber and evacuate to a vacuum level of 5×10⁻⁶. -4 Pa, argon gas is introduced at a flow rate of 40 sccm, and the working pressure is controlled at 0.6 Pa to heat the substrate to 200℃.

[0058] S3. Sputtering was performed using a Ce-Ti alloy target with a purity of 99.99% at a working pressure of 0.6 Pa. The target consisted of Ce and Ti in a mass ratio of 10:90. The sputtering power was 100 W, and the sputtering time was 20 min. No substrate bias was applied. A Ce-Ti transition layer with a thickness of 100–200 nm was formed on the substrate surface. The transition layer contained 9.01% Ce and 88.4% Ti, with the remainder being unavoidable impurities (mainly O).

[0059] S4. Argon gas is continuously introduced, and nitrogen gas is introduced simultaneously at a flow rate of 40 sccm. Co-sputtering is performed using a Cr target and a Ce-Ag alloy target. The sputtering power of the Cr target is 200 W, and the Ce-Ag alloy target has a purity of 99.99%, composed of Ce and Ag in a 50:50 mass ratio. The sputtering power of the Ce-Ag alloy target is 60 W, the working pressure is 0.6 Pa, and the sputtering time is 120 min. No substrate bias is applied. A CrAgCeN thin film layer with a thickness of 1.2–2 μm is formed on the surface of the Ce-Ti transition layer and allowed to cool naturally. In the CrAgCeN composite coating obtained in this embodiment, the chemical composition of the CrAgCeN thin film layer, by mass fraction, is: Cr 46.7%, Ag 2.8%, Ce 2.5%, N 39.2%, with the remainder being unavoidable impurities (mainly O).

[0060] It should be noted that the thickness range in the embodiments is caused by the sputtering rate fluctuation when the process parameters are fixed, which is a normal deviation of magnetron sputtering.

[0061] Example 2 The difference between this embodiment and Embodiment 1 is that in step S4, the nitrogen flow rate is 30 sccm.

[0062] In this embodiment, the Ce-Ti transition layer has a Ce content of 8.7%, a Ti content of 82.3%, and the remainder is unavoidable impurities; the chemical composition of the CrAgCeN thin film layer is: Cr 47.2%, Ag 2.2%, Ce 2.8%, N 38.9%, and the remainder is unavoidable impurities.

[0063] Example 3 The difference between this embodiment and Embodiment 1 is that in step S4, the nitrogen flow rate is 20 sccm.

[0064] In this embodiment, the Ce-Ti transition layer has a Ce content of 8.46%, a Ti content of 87.5%, and the remainder is unavoidable impurities; the chemical composition of the CrAgCeN thin film layer is: Cr 48.6%, Ag 1.5%, Ce 2.3%, N 38.1%, and the remainder is unavoidable impurities.

[0065] Example 4 The difference between this embodiment and Embodiment 2 is as follows: In step S2, the argon flow rate is 60 sccm and the working pressure is 0.5 Pa; in step S3, the working pressure is 0.7 Pa, the Ce-Ti target sputtering power is 60 W, and the sputtering time is 20 min; in step S4, the nitrogen flow rate is 40 sccm and the sputtering time is 120 min.

[0066] In this embodiment, the Ce-Ti transition layer has a Ce content of 10.6%, a Ti content of 79.9%, and the remainder is unavoidable impurities; the chemical composition of the CrAgCeN thin film layer is: Cr 49.4%, Ag 2.2%, Ce 2.1%, N 37.3%, and the remainder is unavoidable impurities.

[0067] Example 5 The difference between this embodiment and embodiment 4 is that the working pressure in both step S3 and step S4 is 0.7 Pa.

[0068] In this embodiment, the Ce-Ti transition layer has a Ce content of 9.7%, a Ti content of 81.2%, and the remainder is unavoidable impurities; the chemical composition of the CrAgCeN thin film layer is: Cr 49.1%, Ag 1.9%, Ce 2.2%, N 36.9%, and the remainder is unavoidable impurities.

[0069] Example 6 The difference between this embodiment and embodiment 2 is that in step S4, the sputtering power of the Ce-Ag alloy target is 50W.

[0070] In this embodiment, the Ce-Ti transition layer has a Ce content of 7.3%, a Ti content of 86.1%, and the remainder is unavoidable impurities; the chemical composition of the CrAgCeN thin film layer is: Cr 48.7%, Ag 1.8%, Ce 1.4%, N 36.2%, and the remainder is unavoidable impurities.

[0071] Comparative Example 1 The difference between this comparative example and Example 1 is that in step S3, a Cr target is used instead of a Ce-Ti alloy target for sputtering, the sputtering power is 100W, the sputtering time is 20min, and a Cr transition layer is formed instead of a Ce-Ti transition layer; in step S4, a Ce-Ag alloy target is not used for co-sputtering, and only a Cr target is used to sputter to form a CrN thin film layer under a nitrogen flow rate of 30sccm, instead of a CrAgCeN thin film layer.

[0072] The Cr transition layer prepared in this comparative example has a Cr content of 93.5%, with the remainder being unavoidable impurities; the chemical composition of the CrN thin film layer is as follows: the ratio of Cr content to N content corresponds to the stoichiometric ratio of CrN, with the remainder being unavoidable impurities, and it does not contain Ce and Ag elements.

[0073] Comparative Example 2 The difference between this comparative example and Example 2 is that in step S4, the sputtering power of the Ce-Ag alloy target is 90W (60W in Example 2).

[0074] The chemical composition of the CrAgCeN composite coating prepared in this comparative example, by mass fraction, is: Cr 46.1%, Ag 2.1%, Ce 4.5%, N 37.2%, with the remainder being unavoidable impurities.

[0075] Experimental Example 1 This experimental example characterizes the morphology of the CrAgCeN composite coatings prepared in Examples 1-3, and the results are as follows: Figures 1-3 As shown. Among them, Figure 1 The image shows the SEM image of the CrAgCeN composite coating prepared in Example 1. Figure 2 The image shows the SEM image of the CrAgCeN composite coating prepared in Example 2. Figure 3 The image shows the morphology of the CrAgCeN composite coating prepared in Example 3 using SEM.

[0076] Depend on Figures 1-3 It is evident that the composite coatings prepared in each embodiment exhibit uniform structure and dense composition, without obvious structural defects such as pores or cracks. Cross-sectional SEM measurements show that the thickness of the composite coatings obtained in each embodiment ranges from 1.2 to 2 μm. This thickness range provides effective wear-resistant protection for the substrate, and no stress concentration or interface peeling phenomena caused by excessive thickness were observed within the coating, indicating that the preparation process of this application has good stability and consistent coating quality.

[0077] Experiment Example 2 In this experimental example, a nanoindenter and a tribometer were used to test the film-substrate adhesion, hardness, and average coefficient of friction of the composite films obtained in the above examples and comparative examples. The film-substrate adhesion and coefficient of friction were tested on a steel substrate, while other test items were conducted on a single-crystal silicon substrate. Hardness was tested with an indentation depth of 100 nm and a load of 50 mN. For film-substrate adhesion testing, the scratching speed was 6 mm / min, and the maximum loading force was 150 N. For the coefficient of friction testing, the friction radius was 3 mm, the grinding ball diameter was 6 mm, the rotation speed was 336 r / min, and the load was 3 N. The test results of the thin films are shown in Table 1.

[0078] Table 1 Performance of CrAgCeN composite coating

[0079] As can be seen from the results in Table 1, the CrAgCeN composite coatings obtained in the examples have good properties such as film-substrate adhesion, hardness, and average friction coefficient, among which the composite film of Example 2 has the best performance.

[0080] Figures 4-6 The images show SEM images of the wear track morphology of the CrAgCeN composite coatings prepared in Examples 1-3 after tribological tests. Figures 4-6 It can be seen that the wear track morphology of each embodiment exhibits varying degrees of furrowing characteristics, among which the most prominent are... Figure 5 The wear morphology of Example 2 shown is the least severe, with the narrowest furrow width and shallowest depth, indicating that the CrAgCeN composite coating of Example 2 has the best wear resistance. This is consistent with the friction coefficient (0.373) and hardness (16.4 GPa) data of Example 2 in Table 1.

[0081] The friction coefficient curves of the CrAgCeN composite coatings prepared in Examples 1-3 under dry friction conditions at room temperature are shown below. Figure 7 As shown. By Figure 7 It can be seen that the friction coefficient of the CrAgCeN composite coating prepared under different working pressures varies significantly: when the working pressure is 0.6 Pa (corresponding to Example 1), the friction coefficient of the coating is the smallest, and it can maintain stable fluctuations during friction without violent oscillations; when the working pressure deviates from 0.6 Pa (Working pressure of 0.6 Pa but nitrogen flow rate of 30 sccm in Example 2, working pressure of 0.6 Pa but nitrogen flow rate of 20 sccm in Example 3), the fluctuation range of the friction coefficient increases, and the stability decreases. Figures 4-6 The wear morphology of the coating in Example 2, with a working pressure of 0.6 Pa, showed the least wear, further confirming that 0.6 Pa is a better deposition pressure parameter.

[0082] Based on the above experimental results, the mechanism of action of the Ce-doped CrN thin film in this application can be summarized as follows.

[0083] (1) Grain refinement effect. Ce has an atomic radius of 0.182 nm. During the nucleation of CrN grains, the incorporation of Ce atoms can increase the lattice distortion energy and improve the nucleation rate, thereby reducing the size of the crystal phase after grain nucleation. At the same time, in the composition design of this application, the proportion of CrN phase in the CrAgCeN film is higher, so the grain refinement of the film is more obvious. It can also be seen from the wear track morphology that the CrAgCeN composite coating surface of this application has a narrower furrow width, indicating that the wear particles generated during the friction process are finer, which is beneficial to reducing the cutting effect of abrasive wear on the coating.

[0084] (2) The friction-reducing and lubricating effect of CeO2. During the friction process, CeO2 crystal phase with certain friction-reducing and wear-resistant properties will precipitate in the thin film crystal phase structure. As an oxide with lubricating properties, CeO2 can act as a solid lubricant at the friction interface, reduce the shear force between the friction pairs, and thus make the friction process more stable, which is macroscopically manifested as a reduction in the coefficient of friction.

[0085] (3) Window effect of rare earth content. Since Ce-Ag alloy targets are easily oxidized during sputtering, it is necessary to effectively control process parameters such as deposition pressure, gas flow rate, and target power. Otherwise, target poisoning may occur, affecting the compositional stability and deposition quality of the film. In addition, the content of rare earth elements has a significant impact on the performance of the film: if the rare earth content is too low, the activity of rare earth elements cannot be fully utilized, and it will not play a role in improving the performance of the film; however, if the rare earth content is too high, it will lead to instability in the internal crystal phase structure of the film, increase the internal stress of the film, and significantly reduce the overall performance of the film. Therefore, both excessive and insufficient rare earth content will cause the deterioration of the film performance. Figure 8 The image shows the wear track morphology after increasing the Ce content (corresponding to Comparative Example 2 with a Ce content of 4.5%). The film surface shows obvious peeling, the overall structure is destroyed, and the tribological properties deteriorate sharply, further verifying the existence of the Ce content window effect.

[0086] Experimental Example 3 This experiment characterizes the high-temperature oxidation resistance of the CrAgCeN composite coating prepared in Example 2 to verify the structural stability and oxidation resistance of the coating under wide temperature range conditions.

[0087] X-ray diffraction (XRD) was used to perform step-scaling scanning tests on the coating of Example 2 within a temperature range of 100°C to 500°C. The results are as follows: Figure 9 As shown. By Figure 9It can be seen that when the temperature rises to 500℃, no diffraction peaks of the Cr2N phase appear in the XRD pattern of the coating, indicating that the CrN phase in the coating does not undergo a phase transformation to Cr2N within this temperature range, and the thermal stability of the CrN hard phase is good. However, it is worth noting that as the temperature rises from 100℃ to 500℃, the preferred orientation of the coating gradually changes from the (200) crystal plane to the (111) crystal plane. This change is due to the rearrangement of crystal orientation caused by the gradual release of residual stress during the heating process. In addition, when the temperature rises to 500℃, a weak Cr2O3 diffraction peak appears at the 42.67° position, which is due to the small amount of oxidation products generated by the reaction of oxygen adsorbed on the coating surface with Cr during the high-temperature oxidation experiment. Nevertheless, the XRD pattern of the CrAgCeN coating is still dominated by CrN diffraction peaks, indicating that the main structure of the coating remains stable within the temperature range of this experiment.

[0088] To further verify the retention of nitrogen in the coating at high temperatures, energy dispersive spectroscopy (EDS) was used to analyze the elemental composition of the coating after oxidation at 500℃. The results are as follows: Figure 10 As shown. By Figure 10 It can be seen that the nitrogen element in the coating did not undergo a large amount of release or escape, and the atomic percentage of nitrogen element remained close to the level of the original deposition state, indicating that the CrN phase did not undergo significant high-temperature decomposition.

[0089] The XRD and EDS results show that the CrAgCeN composite coating prepared in Example 2 of this application exhibits excellent high-temperature oxidation resistance and structural stability below 500℃. The CrN phase did not undergo the unfavorable phase transformation to Cr2N, and no large-scale release of nitrogen occurred; only slight oxidation was observed on the surface. This high-temperature stability provides a reliable structural guarantee for the application of this coating in high-temperature components such as aero-engine bearings.

[0090] Experiment Example 4 To evaluate the mechanical properties of the coatings prepared in Example 2 and Comparative Examples 1-2 at different temperatures, the hardness, elastic modulus, and wear resistance of the coatings prepared in Example 2 and Comparative Examples 1-2 were tested. The hardness and elastic modulus of the coatings were analyzed using an iNano nanoindentation apparatus, and a Berkovich indenter was used for hardness testing. The test load used in the iNano nanoindentation apparatus was 50 mN, and the maximum indentation depth did not exceed 1 / 10 of the film thickness. Wear resistance was characterized by the coefficient of friction and wear rate. The coefficient of friction was obtained by testing with a high-temperature tribometer. The parameters used in the tribometer test were as follows: friction radius of 3 mm, grinding ball diameter of 6 mm, rotation speed of 336 r / min, and normal load of 5 N. The wear rate was calculated using the formula W=V / (F×L) (where V is the wear volume of the wear track, F is the normal load applied in the tribometer test, and L is the friction stroke length). The friction test was a dry friction test, and the temperature used for the friction test ranged from room temperature to 500°C. After the friction test, the appearance morphology of the CrAgCeN composite coating prepared in Example 2 was observed by scanning electron microscopy.

[0091] To ensure the accuracy of the test results for wear resistance, hardness, and elastic modulus, a CrAgCeN coating deposited on the surface of a metal substrate is used to test wear resistance, while a CrAgCeN coating deposited on the surface of a Si substrate is used to test hardness and elastic modulus. Since the nanoindenter calibration is performed on a Si substrate, using a Si substrate for hardness testing can ensure the accuracy of the coating hardness test.

[0092] The test results of hardness and elastic modulus of each coating are shown in Table 2, and the test results of wear resistance in the range of room temperature to 500℃ are shown in Table 3.

[0093] Table 2. Hardness and elastic modulus of the CrAgCeN composite coatings of Examples 2 and Comparative Examples 1-2

[0094] Note: H / E represents the ratio of the hardness to the elastic modulus of the nitride coating.

[0095] Table 3. Wear resistance properties of the CrAgCeN composite coatings prepared in Example 2 and Comparative Examples 1-2

[0096] As shown in Table 2, the H / E value (the ratio of hardness to elastic modulus) of the CrAgCeN composite coating prepared in Example 2 is greater than that of Comparative Example 1 to 2 at all test temperatures, indicating that the nitride coating doped with rare earth element Ce has a higher resistance to plastic deformation.

[0097] Table 3 shows that the wear amount of the CrAgCeN composite coating prepared in Example 2 at room temperature is significantly less than that of Comparative Examples 1-2, indicating that the doping of rare earth elements gives the coating superior tribological properties. Further comparison of tribological properties at different temperatures reveals that the coefficient of friction and wear amount of the coating are both lower at high temperatures than at room temperature, with the coefficient of friction (0.35) and wear amount (8.7 × 10⁻⁶) at 300℃ being the lowest. -7 mm 3 The optimal value is (N·m). The analysis suggests that the mechanism for this performance improvement lies in the synergistic lubrication effect between the oxides formed during the friction process and CeO2 and Ag. However, the oxides are insufficient at room temperature, resulting in relatively large friction and wear.

[0098] Figure 11 and Figure 12 The images show the SEM images of the CrAgCeN composite coating prepared in Example 2 after high-temperature friction tests at 300℃ and 500℃, respectively. Figure 11 It can be seen that after the 300℃ friction test, the surface wear marks of the coating are shallow and the furrows are narrow, with no obvious peeling pits or cracks observed. This indicates that the coating maintains good integrity and wear resistance at this temperature, which is consistent with the lowest wear amount exhibited at 300℃. Figure 12 It can be seen that after the friction test at 500℃, the wear marks on the coating surface were deeper than those at 300℃, but the overall structure of the coating remained intact, and there was no large-area peeling or coating failure. This confirms that the CrAgCeN composite coating still has acceptable wear resistance at a high temperature of 500℃.

[0099] In summary, the CrAgCeN composite coating prepared in Example 2 of this application is superior to the undoped rare earth Ce comparative example 1 and the high Ce content comparative example 2 in terms of hardness, resistance to plastic deformation (H / E value), and tribological properties at room temperature and high temperature. This indicates that appropriate doping of rare earth Ce (limited to 1.0% to 3.0% in this application) can significantly improve the comprehensive mechanical properties and wide-temperature tribological properties of the CrN-based coating. In particular, the synergistic lubrication effect at 300℃ enables the coating to achieve optimal tribological performance.

[0100] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0101] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A CrAgCeN composite coating, characterized in that, The CrAgCeN composite coating comprises: Ce-Ti transition layer covering the substrate surface; A CrAgCeN thin film layer covering the surface of the Ce-Ti transition layer; The CrAgCeN thin film layer, by mass fraction, is composed of the following chemical components: Ce: 1.0%–3.0%, Ag: 1.5%–3.0%, Cr: 45.0%–50.0%, N: 35.0%–40.0%, with the balance being unavoidable impurities.

2. The CrAgCeN composite coating according to claim 1, characterized in that, The Ce-Ti transition layer is composed of the following chemical components by mass fraction: Ce: 5.0%–15.0%, Ti: 75.0%–95.0%, with the balance being unavoidable impurities.

3. The CrAgCeN composite coating according to claim 1, characterized in that, The thickness of the CrAgCeN thin film is 1.2–2 μm, and the thickness of the Ce-Ti transition layer is 100–200 nm.

4. The CrAgCeN composite coating according to claim 1, characterized in that, The CrAgCeN composite coating meets the following properties: hardness of 12.0~16.5GPa, film-substrate adhesion of 50.0~70.0N, and average friction coefficient of 0.35~0.

55.

5. A method for preparing the CrAgCeN composite coating according to any one of claims 1 to 4, characterized in that, The method includes the following steps: S1. The substrate is ultrasonically cleaned to obtain a pretreated substrate; S2. The pretreated substrate is placed into a vacuum chamber and evacuated to a vacuum level of 5 × 10⁻⁶. -4 Pa, argon gas is introduced, the working pressure is controlled at 0.3-0.8 Pa, and the substrate is heated to 180-220℃; S3. Sputtering is performed using a Ce-Ti alloy target at a working pressure of 0.3 to 0.8 Pa, with a sputtering power of 40 to 100 W and a sputtering time of 10 to 30 min. No substrate bias is applied to form a Ce-Ti transition layer on the substrate surface. S4. Keep argon gas flowing in and simultaneously introduce nitrogen gas at a flow rate of 20–50 sccm. Use a Cr target and a Ce-Ag alloy target for co-sputtering. The sputtering power of the Cr target is 180–230 W, the working pressure is 0.3–0.8 Pa, and the sputtering time is 100–150 min. Do not apply a substrate bias voltage to form a CrAgCeN thin film layer on the surface of the Ce-Ti transition layer, and allow it to cool naturally.

6. The preparation method according to claim 5, characterized in that, In step S1, the ultrasonic cleaning is performed by sequentially cleaning with anhydrous ethanol and then with high-purity acetone; the substrate is a steel substrate or a single-crystal silicon substrate.

7. The preparation method according to claim 5, characterized in that, In step S2, the flow rate of the argon gas is 15–60 sccm.

8. The preparation method according to claim 5, characterized in that, In step S3, the Ce-Ti alloy target has a purity of 99.99% and is composed of Ce and Ti in a mass ratio of 10:

90.

9. The preparation method according to claim 5, characterized in that, In step S4, the Ce-Ag alloy target has a purity of 99.99% and is composed of Ce and Ag in a mass ratio of 50:

50. The sputtering power of the Ce-Ag alloy target is 50-90W.

10. The application of the CrAgCeN composite coating according to any one of claims 1 to 4 in the preparation of wear-resistant coatings on the surface of aero-engine bearings, mechanical seals or high-temperature sliding parts.

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