High-temperature-resistant and wear-resistant gradient structure coating as well as preparation method and application thereof

Abstract

The invention discloses a high-temperature-resistant and wear-resistant gradient structure coating as well as a preparation method and application thereof. The gradient structure coating comprises an AlCrNi layer, an AlCrNiN layer and an AlCrNiN / AlTiN nano multilayer structure which are sequentially deposited on the surface of a matrix. The preparation method comprises the following process steps that S1, a base body is pretreated and then loaded into a coating chamber, and the coating chamber is vacuumized and heated; s2, inert gas is introduced into the coating chamber, a direct-current pulse bias power supply is started, and glow cleaning is conducted on the base body; s3, the air pressure in the coating chamber is adjusted, a Cr target is started, and the substrate is etched; s4, the air pressure in the coating chamber is adjusted, and an AlCrNi sputtering target is started to deposit an AlCrNi layer; s5, nitrogen and inert gas are introduced into the coating chamber, and an AlCrNiN layer is deposited; and S6, the nitrogen flow is adjusted, the AlCrNi sputtering target and the AlTi arc target are started at the same time, and the AlCrNiN / AlTiN nano-multilayer structure is deposited. The coating can be widely applied to the technical field of high-temperature-resistant and wear-resistant coatings.

Description

Technical Field

[0001] This application relates to the field of high-temperature and wear-resistant coating technology, and in particular to a high-temperature and wear-resistant gradient structure coating, its preparation method, and its application. Background Technology

[0002] Dual-fuel engines are widely used due to their ability to efficiently utilize multiple fuels and reduce emissions. Compared to traditional diesel engines, marine dual-fuel engines operate under harsher conditions. Hot-end components such as valves, pistons, and piston rings are subjected to high temperatures, high loads, and high-speed impact coupling during operation. Furthermore, the high humidity and salt spray of the ocean, coupled with the large amount of Cl in the air, further exacerbate the problem. - Corrosion inducers, such as Cl in the air drawn in from the outside when the engine is running. - Na + K + It readily reacts with elements such as S, V, and Pb in the fuel under high-temperature conditions, and the resulting molten salt mixture is deposited in the form of eutectic on the surface of hot-end components such as valves and piston rings. This erodes the protective film on the substrate surface, thereby accelerating the wear of these components and causing sluggish power transmission, which seriously affects the service life of marine dual-fuel engines.

[0003] Currently, commonly used PVD coatings for hot-end components of engines include diamond-like carbon (DLC) coatings and TiAlN coatings. DLC coatings possess high hardness and a low coefficient of friction; however, they are prone to oxidation and decomposition at high temperatures (operating temperatures below 400℃), and the thickness that can be produced is limited, making them unsuitable for the operating conditions of dual-fuel engines. TiAlN coatings exhibit good mechanical properties, oxidation resistance, and high-temperature stability, but their coefficient of friction is high. Clearly, although traditional PVD nitride coatings possess excellent hardness and wear resistance, when facing the high-temperature wear under the long-term high-temperature oxidative environment inside a dual-fuel engine, the coating must withstand not only mechanical wear but also the synergistic effects of oxidative wear and corrosive wear, making it prone to peeling and breakage.

[0004] Therefore, developing a coating that exhibits excellent wear resistance and strong adhesion to the substrate under high temperature, high load, and corrosive environments in dual-fuel engines is of great practical significance for improving the service life of hot-end components of marine dual-fuel engines and ensuring stable and efficient engine operation. Summary of the Invention

[0005] To solve at least one of the above-mentioned technical problems, this application provides a high-temperature and wear-resistant gradient structure coating, its preparation method, and its application. The technical solution adopted is as follows.

[0006] The method for preparing the high-temperature and wear-resistant gradient structure coating provided in this application includes the following process steps:

[0007] S1, after surface polishing and cleaning of the substrate, the substrate is loaded into a coating chamber, the coating chamber is vacuumed and heated;

[0008] S2, inert gas is introduced into the coating chamber, the gas pressure is adjusted to 1.5 to 2.5 Pa, a direct current pulse bias power supply is turned on, the bias voltage is set to -600 to -1000 V, the frequency is set to 50 to 100 kHz, the temperature is adjusted to 300 to 400 ℃, and the substrate is subjected to glow cleaning for 30 to 60 min;

[0009] S3, the gas pressure of the coating chamber is adjusted to 0.5 to 1 Pa, the bias voltage is set to -600 to -1000 V, the frequency is set to 50 to 100 kHz, the Cr target is turned on, and the substrate is etched for 5 to 10 min;

[0010] S4, the gas pressure of the coating chamber is adjusted to 0.3 to 0.8 Pa, the substrate is self-rotated in front of the AlCrNi target, the self-rotation speed is 1 to 4 rpm, the AlCrNi sputtering target is turned on to deposit an AlCrNi layer, and the deposition time is 20 to 60 min;

[0011] S5, nitrogen and inert gas are introduced into the coating chamber, the gas pressure is adjusted to 0.5 to 1 Pa, an AlCrNiN layer is deposited, and the deposition time is 50 to 80 min;

[0012] S6, the nitrogen flow is adjusted, the gas pressure of the coating chamber is adjusted to 0.8 to 1.5 Pa, the substrate is simultaneously self-rotated and revolved, the self-rotation speed is 0 to 2 rpm, the self-rotation speed is 1 to 4 rpm, the AlCrNi sputtering target and the AlTi arc target are simultaneously turned on, an AlCrNiN / AlTiN nano-multilayer structure is deposited, and the deposition time is 100 to 150 min.

[0013] In some embodiments of the present application, in step S4, the power density of the target material is 7 to 12 W / cm 2 , the bias voltage is -75 to -125 V, the frequency is 60 to 120 kHz, and the duty cycle is 50 to 100%.

[0014] In some embodiments of the present application, in step S5, the power density of the target material is 7 to 12 W / cm 2 , the bias voltage is -75 to -125 V, the frequency is 60 to 120 kHz, and the duty cycle is 50 to 100%.

[0015] In some embodiments of the present application, in step S6, the AlCrNiN / AlTiN nano-multilayer structure is deposited by direct current magnetron sputtering and cathode arc evaporation, the power density of the AlCrNi sputtering target is 7 to 10 W / cm 2 , and the power density of the AlTi arc target is 0.8 to 1.3 W / cm2 , the bias is -80 to -160 V, the frequency is 60 to 120 kHz, and the duty cycle is 50 to 100%.

[0016] In some embodiments of the present application, the material of the substrate is one of stainless steel, tool steel and cemented carbide.

[0017] The high-temperature and wear-resistant gradient structure coating provided by the present application is obtained by using the preparation method as described above, and the gradient structure coating comprises an AlCrNi layer, an AlCrNiN layer and an AlCrNiN / AlTiN nano-multilayer structure deposited on the surface of the substrate in sequence.

[0018] In some embodiments of the present application, the thickness of the gradient structure coating is 5.5 to 6.5 μm.

[0019] In some embodiments of the present application, the thickness of the AlCrNi layer is 1.5 to 2 μm, the thickness of the AlCrNiN layer is 1.5 to 2 μm, and the thickness of the AlCrNiN / AlTiN nano-multilayer structure is 2 to 2.5 μm.

[0020] In some embodiments of the present application, the hardness of the gradient structure coating is 30 to 35 GPa, and the elastic modulus is 400 to 450 GPa.

[0021] The high-temperature and wear-resistant gradient structure coating as described above provided by the present application is applied to the surface protection of the hot end parts of a dual-fuel engine.

[0022] The present application has at least the following beneficial effects: the substrate of the gradient structure coating is an AlCrNi layer, the intermediate layer is an AlCrNiN layer, and the top layer is an AlCrNiN / AlTiN nano-multilayer structure. The composition in the coating is a gradient surface, which gradually changes from a metal composition to an increasing proportion of nitride, realizing the continuous change of the coating composition and mechanical properties. The substrate has good adhesion, the intermediate layer reduces stress concentration at high temperature, while providing good oxidation resistance. The surface layer has both toughness and high hardness, effectively improving the wear resistance of the coating surface. The present application can be widely applied to the technical field of high-temperature and wear-resistant coatings.

[0023] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter in the description. BRIEF DESCRIPTION OF DRAWINGS

[0024] The present application will be further illustrated below in combination with the drawings and examples. It should be noted that the examples embodied in the following drawings are exemplary and are used to explain the present application, and cannot be understood as a limitation of the present application.

[0025] Figure 1 Fracture cross-sectional morphology of each coating of Comparative Examples 1 to 3 and Example 1 under SEM.

[0026] Figure 2 Nanoindentation hardness and elastic modulus comparison chart of each coating of Comparative Examples 1 to 3 and Example 1.

[0027] Figure 3 Wear rate and friction coefficient comparison chart of each coating of Comparative Examples 1 to 3 and Example 1 at room temperature.

[0028] Figure 4 Wear rate and friction coefficient comparison chart of each coating of Comparative Examples 1 to 3 and Example 1 at 600°C.

[0029] Figure 5 Three-dimensional morphology chart of wear scar of each coating of Comparative Examples 1 to 3 and Example 1 after room temperature friction test.

[0030] Figure 6 Three-dimensional morphology chart of wear scar of each coating of Comparative Examples 1 to 3 and Example 1 after 600°C friction test. DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described below in detail with reference to the accompanying drawings. Figures 1 to 6 The embodiments of the present application will be described below in detail with reference to the accompanying drawings.

[0032] In the description of the present application, it is to be understood that the orientation or positional relationship indicated by the terms "center", "middle", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0033] In the description of the present application, if the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, within, etc. are understood as including the number. If it is described as first, second, only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0034] In the description of this application, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0035] In the description of this application, the use of terms such as "one embodiment," "some embodiments," "an example," "some instances," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0036] This application relates to a high-temperature and wear-resistant gradient structure coating, which includes an AlCrNi layer, an AlCrNiN layer, and an AlCrNiN / AlTiN nanolayer structure sequentially deposited on the surface of a substrate. Specifically, the AlCrNi layer is deposited on the surface of the substrate, the AlCrNiN layer is deposited on the surface of the AlCrNi layer, and the AlCrNiN / AlTiN nanolayer structure is deposited on the surface of the AlCrNiN layer.

[0037] Furthermore, the thickness of the gradient structure coating is 5.5 to 6.5 μm. If the coating is too thin, it will significantly reduce the protective function of the substrate and result in insufficient wear life, while if the coating is too thick, it will lead to a decrease in coating toughness and poor impact resistance, and the high internal stress will cause the coating to crack and peel off.

[0038] In some examples, the AlCrNi layer thickness ranges from 1.5 to 2 μm. The core function of the AlCrNi layer is to mitigate the difference in thermal expansion coefficients between the substrate and the nitride layer through its own plastic deformation, thereby improving the adhesion between the coating and the substrate and preventing coating peeling. If the AlCrNi layer is too thin, it will result in insufficient stress buffering capacity, thus reducing the adhesion between the coating and the substrate. If the AlCrNi layer is too thick, it will reduce the overall hardness and wear resistance of the coating.

[0039] In some examples, the AlCrNiN layer thickness ranges from 1.5 to 2 μm. The AlCrNiN layer serves as a gradient transition between the AlCrNi layer and the nanomultilayer structure. If the AlCrNiN layer is too thin, the gradient transition effect will be insignificant, stress may concentrate at the interface, and it will fail to provide effective mechanical support for the surface coating. If the AlCrNiN layer is too thick, it may lead to excessively high residual stress in the coating, internal stress accumulation, and potential cracking of the coating, while also increasing surface defects.

[0040] In some examples, the thickness of the AlCrNiN / AlTiN nanolayer structure is 2 to 2.5 μm. As a wear-resistant layer on the surface, if the AlCrNiN / AlTiN nanolayer structure is too thin, the coating's wear life will be insufficient, and it may be quickly worn through under heavy loads or prolonged wear conditions, losing its protective function. If the AlCrNiN / AlTiN nanolayer structure is too thick, it will increase the residual stress inside the coating, which may lead to microcracks, peeling, or even flaking. Simultaneously, the difference in thermal expansion coefficients between different layers in the coating will amplify with increasing thickness, causing interlayer shear stress to exceed the interfacial bonding strength.

[0041] In some examples, the gradient structure coating has a hardness of 30 to 35 GPa and an elastic modulus of 400 to 450 GPa.

[0042] In some examples, the wear rate of the gradient structure coating was 4.5 × 10⁻⁶ under room temperature tribological tests. -7 Up to 5.5×10 -7 mm 3 / N·m, with a friction coefficient COF of 0.7 to 0.8.

[0043] In some examples, the wear rate of the gradient structure coating was 3 × 10⁻⁶ under a tribological test at 600°C. -6 Up to 4×10 -6 mm 3 / N·m, with a friction coefficient COF of 0.5 to 0.6.

[0044] This application relates to the application of a high-temperature and wear-resistant gradient structure coating, characterized in that: the gradient structure coating is applied to the surface protection of hot-end components of a dual-fuel engine.

[0045] This application relates to a method for preparing a high-temperature and wear-resistant gradient structure coating as described above.

[0046] The preparation method includes the following process flow.

[0047] S1. The substrate surface is pretreated, and then the substrate is placed into the coating chamber, which is then evacuated and heated.

[0048] S2, inert gas is introduced into the coating chamber, and the DC pulse bias power supply is turned on to perform glow discharge cleaning on the substrate.

[0049] S3, activate the Cr target to etch the substrate.

[0050] S4, initiate AlCrNi sputtering target deposition of AlCrNi layer.

[0051] S5, nitrogen and inert gas are introduced into the coating chamber to deposit an AlCrNiN layer.

[0052] S6, simultaneously turn on the AlCrNi sputtering target and the AlTi arc target to deposit AlCrNiN / AlTiN nanomultilayer structures.

[0053] It should be noted that in step S1, after the substrate is surface polished and cleaned, it is placed into the coating chamber, and the coating chamber is evacuated and heated.

[0054] Specifically, during substrate pretreatment, the substrate surface is first polished, then ultrasonically cleaned using a metal cleaner and anhydrous ethanol, respectively. Afterward, the substrate surface is dried with a nitrogen-based air blower to remove dust, and then the substrate is placed into the coating chamber. The coating chamber is then evacuated to a vacuum level of 5*10. -3 Pa, the temperature is heated to 350 to 550°C.

[0055] Furthermore, the base material is one of stainless steel, tool steel, and cemented carbide.

[0056] It should be noted that in step S2, inert gas is introduced into the coating chamber and the gas pressure is adjusted to 1.5 to 2.5 Pa. The DC pulse bias power supply is turned on, the bias voltage is set to -600 to -1000 V, the frequency is set to 50 to 100 kHz, the temperature is adjusted to 300 to 400 °C, and the substrate is subjected to glow discharge cleaning for 30 to 60 minutes.

[0057] It should be noted that in step S3, the gas pressure in the coating chamber is adjusted to 0.5 to 1 Pa, the bias voltage is set to -600 to -1000 V, the frequency is set to 50 to 100 kHz, the Cr target is turned on, and the substrate is etched for 5 to 10 minutes.

[0058] It should be noted that in step S4, the gas pressure in the coating chamber is adjusted to 0.3 to 0.8 Pa, the substrate rotating frame rotates in front of the AlCrNi target at a speed of 1 to 4 rpm, the AlCrNi sputtering target is turned on to deposit the AlCrNi layer, and the deposition time is 20 to 60 min.

[0059] Furthermore, in step S4, the power density of the target material is 7 to 12 W / cm². 2The bias voltage is -75 to -125V, the frequency is 60 to 120kHz, and the duty cycle is 50 to 100%.

[0060] It should be noted that in step S5, nitrogen and inert gas are introduced into the coating chamber, the flow ratio of nitrogen to inert gas is set to 0.5:1 to 1:1, the gas pressure is adjusted to 0.5 to 1 Pa, and the AlCrNiN layer is deposited for 50 to 80 minutes.

[0061] If the nitrogen-to-inert gas flow ratio is too low, the nitrogen content in the AlCrNiN layer will be insufficient, resulting in a large amount of metallic phases and metastable nitrides. This leads to a decrease in density and consequently, a decrease in hardness, rendering the layer unable to support the top layer. Under stress, this transition layer is prone to plastic deformation, causing overall coating failure. Conversely, if the nitrogen-to-inert gas flow ratio is too high, the internal stress in the AlCrNiN layer will increase dramatically. The AlCrNiN layer itself will become brittle and lose its stress buffering capacity. The stress gradient within the gradient structure coating will be disrupted, making it prone to microcracks at adjacent interfaces, increasing the risk of coating peeling.

[0062] Furthermore, in step S5, the power density of the target material is 7 to 12 W / cm². 2 The bias voltage is -75 to -125V, the frequency is 60 to 120kHz, and the duty cycle is 50 to 100%.

[0063] It should be noted that in step S6, the nitrogen flow rate is adjusted, and the flow ratio of nitrogen to inert gas is set to 2:1 to 2.5:1. The gas pressure in the coating chamber is adjusted to 0.8 to 1.5 Pa. The substrate's rotating frame rotates and revolves simultaneously, with a rotation speed of 0 to 2 rpm and a rotation speed of 1 to 4 rpm. At the same time, the AlCrNi sputtering target and the AlTi arc target are turned on to deposit the AlCrNiN / AlTiN nanolayer structure for a deposition time of 100 to 150 min.

[0064] If the nitrogen-to-inert gas flow ratio is too low, insufficient nitrogen may lead to incompletely nitrided soft metallic phases in the AlCrNiN / AlTiN nanolayer structure, resulting in blurred nanolayer interfaces, weakened interface strengthening effect, and reduced coating hardness and wear resistance. Simultaneously, the metal-rich coating oxidizes at higher temperatures. Conversely, if the nitrogen-to-inert gas flow ratio is too high, target poisoning can cause a sharp decrease in sputtering rate and unstable arcs, leading to an increase in large particles and defects on the coating surface. Furthermore, excessive internal stress in the coating may cause peeling, cracking, and flaking.

[0065] Furthermore, AlCrNiN / AlTiN nanolayer structures were deposited using DC magnetron sputtering and cathode arc evaporation, with the AlCrNi sputtering target having a power density of 7 to 10 W / cm².2 The power density of the AlTi arc target ranges from 0.8 to 1.3 W / cm². 2 The bias voltage is -80 to -160V, the frequency is 60 to 120kHz, and the duty cycle is 50 to 100%.

[0066] It should be noted that argon is used as the inert gas introduced into the coating chamber during the above process.

[0067] This application employs magnetron sputtering combined with cathode arc evaporation to deposit a gradient structure coating. The coating composition varies in a gradient manner, with the coating design showing an increasing proportion of metal components to nitrides, thus achieving continuous variation in coating composition and mechanical properties.

[0068] The bottom AlCrNi layer exhibits strong adhesion to the substrate and provides a certain degree of plastic deformation capacity at high temperatures, preventing cracking of the hard layer on the coating surface. The intermediate AlCrNiN layer serves as a transition layer for hardness and elastic modulus, reducing stress concentration at high temperatures while providing good oxidation resistance. The surface AlCrNiN / AlTiN nanolayered structure combines the toughness of the AlCrNiN layer with the high hardness of the AlTiN layer, forming a synergistic structure that is hard yet not brittle. This effectively improves the surface wear resistance of the coating, meeting the performance requirements of wear-resistant protective coatings for the hot-end components of dual-fuel engines.

[0069] The contents of this application are described in detail below with reference to specific embodiments. It should be noted that the following description is merely illustrative and not a specific limitation of this application.

[0070] Example 1

[0071] In this embodiment 1, a high-temperature and wear-resistant gradient structure coating is prepared on a stainless steel substrate using a PVD vacuum coating equipment, a composite arc ion plating technology, and a magnetron sputtering technology. The coating contains gradient components.

[0072] The composition (weight percentage) of the arc target is as follows: Al: 67Ti33. The composition (atomic percentage) of the magnetron splicing target is as follows: Target 1: Al50Cr50; Target 2: Al42.5Cr42.5Ni15; Target 3: Al40Cr40Ni20; Target 4: Al40Cr40Ni20.

[0073] The preparation process is as follows.

[0074] S1, after surface cleaning of the substrate, it is transferred to the coating chamber, where a vacuum of 5*10 is applied. -3 Pa, the temperature is heated to 400℃, and the revolution speed of the rotating frame is set to 3 rpm.

[0075] S2. Argon gas is introduced into the coating chamber, with the gas pressure set to 2.0 Pa and the temperature set to 350 °C. The DC pulse bias power supply is turned on, with the bias voltage set to -1000 V and the frequency set to 80 kHz. The substrate is then subjected to glow discharge cleaning for 30 minutes.

[0076] S3, adjust the argon gas flow rate, set the gas pressure in the coating chamber to 0.6 Pa, the bias voltage to -800 V, the frequency to 80 kHz, turn on the Cr target, and set the target current density to 1.0 A / cm². 2 The substrate surface was etched for 8 minutes.

[0077] S4, adjust the argon gas flow rate, set the gas pressure in the coating chamber to 0.53 Pa, the bias voltage to -100 V, turn on the AlCrNi magnetron target, and set the average power density on the target surface to 10 W / cm². 2 The substrate's rotating frame rotates in front of the AlCrNi magnetron target at a speed of 3 rpm, and the deposition time is 40 min.

[0078] S5, maintain the argon gas flow rate and open the nitrogen gas flow valve. Set the gas pressure in the coating chamber to 0.65 Pa and the average power density of the target surface to 10 W / cm². 2 The deposition time was 60 minutes.

[0079] S6, maintain the argon gas flow rate, adjust the nitrogen gas flow rate, set the gas pressure in the coating chamber to 1.0 Pa, turn on the AlTi arc target, and set the target current density to 1.0 A / cm². 2 The substrate's rotating frame simultaneously revolves around and rotates on its own axis, with a revolution speed of 1 rpm and a rotation speed of 3 rpm, and a deposition time of 120 min.

[0080] In Example 1, the above steps were used to prepare a gradient structure coating with AlCrNi layer, AlCrNiN layer, and AlCrNiN / AlTiN nanomultilayer structure.

[0081] Comparative Example 1

[0082] Comparative Example 1: AlCrNiN coating was prepared. The preparation process is as follows.

[0083] D1. After surface cleaning of the substrate, it is transferred to the coating chamber, where a vacuum of 5*10 is applied. -3 Pa, the temperature is heated to 400℃, and the revolution speed of the rotating frame is set to 3 rpm.

[0084] D2. Argon gas is introduced into the coating chamber, with the pressure set to 2.0 Pa and the temperature set to 350 °C. The DC pulse bias power supply is turned on, with the bias voltage set to -1000 V and the frequency set to 80 kHz. The substrate is then subjected to glow discharge cleaning for 30 minutes.

[0085] D3. Adjust the argon gas flow rate, set the gas pressure in the coating chamber to 0.6 Pa, the bias voltage to -800 V, the frequency to 80 kHz, turn on the Cr target, and set the target current density to 1.0 A / cm². 2 The substrate surface was etched for 8 minutes.

[0086] D4. Argon and nitrogen are introduced into the coating chamber at a flow rate of 70 sccm and 50 sccm, respectively. The gas pressure is set to 0.65 Pa, and the bias voltage is -100 V. The AlCrNi magnetron target is turned on, and the average power density on the target surface is 10 W / cm². 2 The substrate's rotating frame rotates in front of the target, and the deposition time is 150 minutes.

[0087] Comparative Example 2

[0088] Comparative Example 2: AlTiN coating was prepared. The preparation process is as follows.

[0089] D1. After surface cleaning of the substrate, it is transferred to the coating chamber, where a vacuum of 5*10 is applied. -3 Pa, the temperature is heated to 400℃, and the revolution speed of the rotating frame is set to 3 rpm.

[0090] D2. Argon gas is introduced into the coating chamber, with the pressure set to 2.0 Pa and the temperature set to 350 °C. The DC pulse bias power supply is turned on, with the bias voltage set to -1000 V and the frequency set to 80 kHz. The substrate is then subjected to glow discharge cleaning for 30 minutes.

[0091] D3. Adjust the argon gas flow rate, set the gas pressure in the coating chamber to 0.6 Pa, the bias voltage to -800 V, the frequency to 80 kHz, turn on the Cr target, and set the target current density to 1.0 A / cm². 2 The substrate surface was etched for 8 minutes.

[0092] D4. Close the argon flow valve, introduce nitrogen into the coating chamber, set the gas pressure to 3.0 Pa, the bias voltage to -100 V, and turn on the AlTi arc target. The current density of the target material is 1.0 A / cm². 2 The substrate's rotating frame rotates in front of the target, and the deposition time is 150 minutes.

[0093] Comparative Example 3

[0094] Comparative Example 3: AlCrNiN / AlTiN coating was prepared. The preparation process is as follows.

[0095] D1. After surface cleaning of the substrate, it is transferred to the coating chamber, where a vacuum of 5*10 is applied. -3 Pa, the temperature is heated to 400℃, and the revolution speed of the rotating frame is set to 3 rpm.

[0096] D2. Argon gas is introduced into the coating chamber, with the pressure set to 2.0 Pa and the temperature set to 350 °C. The DC pulse bias power supply is turned on, with the bias voltage set to -1000 V and the frequency set to 80 kHz. The substrate is then subjected to glow discharge cleaning for 30 minutes.

[0097] D3. Adjust the argon gas flow rate, set the gas pressure in the coating chamber to 0.6 Pa, the bias voltage to -800 V, the frequency to 80 kHz, turn on the Cr target, and set the target current density to 1.0 A / cm². 2 The substrate surface was etched for 8 minutes.

[0098] D4. Argon and nitrogen are introduced into the coating chamber at a flow rate of 70 sccm and 145 sccm, respectively. The pressure is 1.0 Pa, the bias voltage is -100 V, and the magnetron target is activated. The average power density on the target surface is 10 A / cm². 2 Turn on the AlTi arc target; the current density of the target material is 1.0 A / cm². 2 The substrate simultaneously rotates on its own axis and revolves around the sun. The rotation speed is 3 rpm and the revolution speed is 1 rpm. The deposition time is 240 min.

[0099] The surfaces and cross sections of the coatings in Example 1 and Comparative Examples 1 to 3 were analyzed by scanning electron microscopy. The hardness and elastic modulus of the coatings were detected and analyzed by nanoindentation test. The three-dimensional contours of the wear marks on the coatings were observed by a ball-and-disc high-temperature tribometer and a laser notarized focusing microscope, and the wear rate of the coatings was calculated.

[0100] Figure 1 The images show cross-sectional SEM images of the coatings in Comparative Examples 1 to 3 and Example 1. As can be seen from the images, the coating in Example 1, due to its gradient composition, achieves a gradual transition from a larger columnar crystal structure to a more compact columnar crystal growth structure from the substrate to the surface, and exhibits good adhesion to the substrate.

[0101] Figure 2 The hardness and elastic modulus test results are for the coatings of Comparative Examples 1 to 3 and Example 1. Specifically, the hardness of the coating in Comparative Example 1 is 12.5 ± 0.7 GPa, and the elastic modulus is 277 ± 10.3 GPa; the hardness of the coating in Comparative Example 2 is 30.3 ± 0.9 GPa, and the elastic modulus is 393 ± 16.4 GPa; the hardness of the coating in Comparative Example 3 is 30.1 ± 0.6 GPa, and the elastic modulus is 408 ± 8.8 GPa; and the hardness of the coating in Example 1 is 29.5 ± 0.7 GPa, and the elastic modulus is 401 ± 12.4 GPa.

[0102] Depend on Figure 1As can be seen from the results, the coating in Example 1, due to its gradient composition, exhibits hardness and elastic modulus similar to those of Comparative Examples 2 and 3, while showing a significant improvement compared to the coating in Comparative Example 1. This demonstrates that the gradient design allows the coating to possess both the toughness of the AlCrNiN layer and the high hardness of the AlTiN layer.

[0103] Figure 3 This is a comparison chart of the wear rate and coefficient of friction of each coating in Comparative Examples 1 to 3 and Example 1 at room temperature. The wear rate of the coating in Comparative Example 1 is 3.79 × 10⁻⁶. -7 mm 3 / N·m, the coefficient of friction COF is 0.46; the wear rate of the coating in Comparative Example 2 is 3.12×10 -4 mm 3 / N·m, the coefficient of friction COF is 0.72; the wear rate of the coating in Comparative Example 3 is 2.16×10 - 7 mm 3 / N·m, the coefficient of friction COF is 0.66; the wear rate of the coating in Example 1 is 5.03×10 -7 mm 3 / N·m, the coefficient of friction COF is 0.76.

[0104] Depend on Figure 3 As can be seen, the wear rate of the coating in Example 1 is significantly lower than that in Comparative Example 2, and the wear rate of Example 1 is similar to that of Comparative Examples 1 and 3. Example 1 exhibits good wear resistance. This indicates that under room temperature conditions, a reasonable gradient design can effectively improve the abrupt change in the performance of the substrate and the coating. The high hardness of the outer layer resists abrasive and adhesive wear, while the toughness of the inner layer and the intermediate transition layer prevent the coating from cracking and peeling, thus effectively improving the wear resistance of the coating at room temperature.

[0105] Figure 4 The graph shows a comparison of the wear rate and coefficient of friction of the coatings in Comparative Examples 1 to 3 and Example 1 at 600°C. The wear rate of the coating in Comparative Example 1 is 3.67 × 10⁻⁶. -5 mm 3 / N·m, the coefficient of friction COF is 0.68; the wear rate of the coating in Comparative Example 2 is 3.64×10 -5 mm 3 / N·m, the coefficient of friction COF is 0.7; the wear rate of the coating in Comparative Example 3 is 2.21×10 - 5 mm 3 / N·m, the coefficient of friction COF is 0.67; the wear rate of the coating in Example 1 is 3.6×10 -6 mm 3 / N·m, the coefficient of friction COF is 0.59.

[0106] Depend on Figure 4 As can be seen, compared with the friction test under room temperature conditions, the wear rates of the coatings in Comparative Examples 1 and 3 increased to varying degrees under the high temperature condition of 600℃. Although the wear rate of Comparative Example 2 decreased to some extent, it was still higher than that of the coating in Example 1. Furthermore, the coefficient of friction of the coating in Example 1 decreased significantly compared with the friction test under room temperature conditions and was lower than that of the coatings in Comparative Examples 1 to 3. This indicates that the gradient design, from pure metal to nitride content, achieved a continuous transition in composition and performance, reducing the internal stress caused by thermal expansion differences at high temperatures, thereby significantly improving the wear resistance of the coating at high temperatures. The nano-multilayer structure of the surface layer promoted the uniform growth of oxides at high temperatures, and the addition of Ni element improved the toughness of the coating, reducing abrasive wear caused by brittle fracture at high temperatures and thus lowering the coefficient of friction.

[0107] Figure 5 The three-dimensional morphology of the wear tracks observed under a laser confocal microscope after room temperature friction tests were performed on the coatings of Comparative Examples 1 to 3 and Example 1. Specifically, the wear track depth of the coating in Comparative Example 1 was 0.25 μm and the width was 182 μm; the wear track depth of the coating in Comparative Example 2 was 24.8 μm and the width was 751 μm; the wear track depth of the coating in Comparative Example 3 was 0.2 μm and the width was 210 μm; and the wear track depth of the coating in Example 1 was 0.25 μm and the width was 236 μm.

[0108] according to Figure 5 According to the records, the coating of Comparative Example 2 had worn through to the substrate, and the wear track depth and width of the coatings of Example 1 and Comparative Examples 1 and 3 were similar. Because the coating of Comparative Example 2 was hard and brittle, it could not buffer stress through the substrate during wear. Under stress, cracks formed due to the plastic deformation of the substrate, leading to large-scale peeling of the coating and accelerated wear until it was worn through. Example 1, through its coating structure with a compositional gradient, effectively achieved a performance transition from the substrate to the coating surface, thus maintaining good wear resistance at room temperature.

[0109] Figure 6 The three-dimensional morphology of the wear tracks observed under a laser confocal microscope after the coatings of Comparative Examples 1 to 3 and Example 1 underwent a friction test at 600°C. Specifically, the wear track depth of the coating in Comparative Example 1 was 3.7 μm and the width was 378 μm; the wear track depth of the coating in Comparative Example 2 was 4.0 μm and the width was 364 μm; the wear track depth of the coating in Comparative Example 3 was 2.7 μm and the width was 327 μm; and the wear track depth of the coating in Example 1 was 0.65 μm and the width was 181 μm.

[0110] according to Figure 6According to the records, the wear track depth and width of the coatings in Comparative Examples 1 to 3 were similar, while the wear track depth and width of the coating in Example 1 were significantly smaller than those in Comparative Examples 1 to 3. Obvious cracks appeared at the edges of the wear tracks in the coating of Comparative Example 2. The coating in Example 1, due to the change in compositional gradient, mitigated the abrupt change in performance from the substrate to the coating surface, reduced stress concentration at high temperatures, and maintained good wear resistance even at high temperatures.

[0111] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. A method for producing a high-temperature-resistant and wear-resistant gradient-structured coating, characterized by: Comprising S1, after surface polishing and cleaning of the substrate, the substrate is loaded into a coating chamber, the coating chamber is vacuumed and heated; S2, inert gas is introduced into the coating chamber, the gas pressure is adjusted to 1.5-2.5 Pa, a direct current pulse bias power supply is turned on, the bias voltage is set to-600 to-1000 V, the frequency is set to 50-100 kHz, the temperature is adjusted to 300-400℃, and the substrate is subjected to glow cleaning for 30-60 min; S3, the gas pressure of the coating chamber is adjusted to 0.5-1 Pa, the bias voltage is set to-600 to-1000 V, the frequency is set to 50-100 kHz, the Cr target is turned on, and the substrate is etched for 5-10 min; S4, the gas pressure of the coating chamber is adjusted to 0.3-0.8 Pa, the substrate is self-rotated in front of the AlCrNi target, the self-rotation speed is 1-4 rpm, the AlCrNi sputtering target is turned on to deposit an AlCrNi layer, and the deposition time is 20-60 min; S5, nitrogen and inert gas are introduced into the coating chamber, the gas pressure is adjusted to 0.5-1 Pa, an AlCrNiN layer is deposited, and the deposition time is 50-80 min; S6, the nitrogen flow is adjusted, the gas pressure of the coating chamber is adjusted to 0.8-1.5 Pa, the substrate is self-rotated and revolved at the same time, the self-rotation speed is 0-2 rpm, the self-rotation speed is 1-4 rpm, the AlCrNi sputtering target and the AlTi arc target are turned on at the same time, an AlCrNiN / AlTiN nano-multilayer structure is deposited, and the deposition time is 100-150 min.

2. The method of claim 1, wherein: In step S4, the target material has a power density of 7 to 12 W / cm 2 , a bias voltage of -75 to -125 V, a frequency of 60 to 120 kHz, and a duty cycle of 50 to 100%.

3. The method of claim 1, wherein the method further comprises: In step S5, the target material has a power density of 7 to 12 W / cm 2 , a bias voltage of -75 to -125 V, a frequency of 60 to 120 kHz, and a duty cycle of 50 to 100%.

4. The method of claim 1, wherein the method further comprises: In step S6, AlCrNiN / AlTiN nano-multilayer structure is deposited by direct current magnetron sputtering and cathode arc evaporation, the power density of AlCrNi sputtering target is 7 to 10 W / cm 2 , the power density of AlTi arc target is 0.8 to 1.3 W / cm 2 , the bias voltage is -80 to -160 V, the frequency is 60 to 120 kHz, and the duty cycle is 50 to 100%.

5. The method of claim 1, wherein: The material of the substrate is one of stainless steel, tool steel and hard alloy.

6. A high temperature wear resistant gradient structured coating, characterized by: The gradient structure coating is deposited by the preparation method of any one of claims 1-5, and comprises an AlCrNi layer, an AlCrNiN layer and an AlCrNiN / AlTiN nano-multilayer structure deposited on the surface of the substrate in sequence.

7. The high-temperature oxidation and wear resistant gradient structured coating of claim 6, wherein: The thickness of the gradient structure coating is 5.5-6.5 μm.

8. The high-temperature wear-resistant gradient structured coating according to claim 6 or 7, characterized in that: The thickness of the AlCrNi layer is 1.5-2 μm, the thickness of the AlCrNiN layer is 1.5-2 μm, and the thickness of the AlCrNiN / AlTiN nano-multilayer structure is 2-2.5 μm.

9. The high-temperature oxidation and wear resistant gradient structured coating of claim 6, wherein: The hardness of the gradient structure coating is 30-35 GPa, and the elastic modulus is 400-450 GPa.

10. Use of a high-temperature wear-resistant gradient coating according to any one of claims 6 to 9, characterized in that: The gradient structure coating is applied to the surface protection of the hot end parts of a dual-fuel engine.

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