A post-treatment method for improving the wear resistance and corrosion resistance of CrAlN coating

Abstract

The present invention discloses a cyclic heat treatment method for a wear-resistant and corrosion-resistant CrAlN coating, comprising the following steps: Step S1: pretreating a base material; Step S2: etching the base material surface to remove the oxide layer and impurities; Step S3: depositing a metallic Cr transition layer on the base material; Step S4: depositing a CrAlN coating on the metallic Cr transition layer; and Step S5: cyclic heat treatment of the base material on which the CrAlN coating is deposited. This method solves the problem that conventional CrAlN coatings cannot be used in extremely harsh environments.

Description

Technical Field

[0001] The invention belongs to the technical field of surface engineering protection and relates to a post-processing method for improving the wear resistance and corrosion resistance of a CrAlN coating. Background Art

[0002] Since the beginning of the 21st century, with the advancement of human society and the further development of marine resources, humans have begun to pay attention to the performance of materials in the harsh marine environment. Materials that combine high strength, friction resistance, and corrosion resistance have become particularly important in these harsh marine environments. Hard protective coatings can be applied to marine equipment and components such as ships, offshore jack-up platforms, plunger pumps, and thrust bearings. Mechanical components on major engineering equipment such as ships, offshore jack-up platforms, naval vessels, and oil and gas platforms, including plunger pumps, valves, gears, slide valves, and thrust bearings, are subject to severe corrosion from seawater and wear on mechanical surfaces, which can easily lead to performance degradation and failure. Once friction corrosion occurs, the large size of marine equipment necessitates significant labor, material, and financial resources for repair and maintenance. Furthermore, friction corrosion failure can lead to serious accidents. Surface friction corrosion is unavoidable for metal materials operating in such harsh marine environments. According to incomplete statistics, the direct economic losses caused by friction corrosion of metal materials in seawater have reached trillions of dollars in recent years. Therefore, the need for developing metal surface protective materials that combine excellent mechanical properties with friction and corrosion resistance is extremely urgent, aiming to overcome a major bottleneck in the development of marine equipment. One of the most effective methods currently available is to apply functional protective coatings to the surfaces of mechanical equipment and components to ensure long-term stable operation and extend their service life. A growing number of researchers are dedicated to developing functional protective coatings suitable for the harsh conditions of the ocean's harsh environment. In the field of surface engineering, coatings that combine excellent mechanical properties with friction and corrosion resistance hold great significance and potential as protective materials in harsh environments such as the ocean.

[0003] CrAlN coating, an important PVD hard coating, is widely used due to its high hardness, excellent wear resistance, and corrosion resistance. However, with the development of the industry and the increasing demand for service conditions, traditional CrAlN-coated friction component parts cannot be used in extremely harsh environments, especially in marine corrosive environments. The strong corrosive effects of seawater and wear problems on mechanical surfaces can easily lead to degradation and failure of their service performance.

[0004] Therefore, there is a need in the art to develop a post-treatment method for improving the wear resistance and corrosion resistance of the CrAlN coating, so as to improve the tribological properties and corrosion resistance of the CrAlN coating. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides a post-treatment method for improving the wear resistance and corrosion resistance of CrAlN coatings, which solves the problem that conventional CrAlN coatings cannot be used in extremely harsh environments.

[0006] The technical solution adopted by the present invention is a post-treatment method for improving the wear resistance and corrosion resistance of CrAlN coating, comprising the following steps:

[0007] Step S1: pre-treating the base material;

[0008] Step S2: etching the surface of the base material to remove the oxide layer and impurities;

[0009] Step S3, depositing a metal Cr transition layer on the base material;

[0010] Step S4: depositing a CrAlN coating on the metal Cr transition layer;

[0011] Step S5: performing cyclic heat treatment on the base material on which the CrAlN coating is deposited.

[0012] Furthermore, the step S1 is specifically as follows:

[0013] All matrix materials were ultrasonically cleaned in acetone and anhydrous ethanol solutions for 15 min to 25 min, and then dried with dry nitrogen.

[0014] Furthermore, the step S2 is specifically as follows:

[0015] The pretreated substrate material was placed in the chamber of a multi-arc ion plating deposition equipment and vacuumed. Argon gas was then passed into the chamber and maintained at 90-110 sccm. Deposition bias voltages of -850-950 V, -1050-1150 V, and -1151 V-1250 V were selected to etch the substrate surface to remove the oxide layer and impurities.

[0016] Furthermore, the step S3 is specifically as follows:

[0017] The substrate material from which the oxide layer and impurities have been removed is subjected to transition layer deposition. The Cr target current is set to 50~70 A, the substrate bias voltage is -15~-25 V, the argon gas flow rate is 180~220 sccm, and the deposition time is 8~12 min to deposit a metal Cr transition layer on the substrate material.

[0018] Furthermore, the step S4 is specifically as follows:

[0019] CrAlN coating was deposited on the surface of the substrate material with a metal Cr transition layer deposited using a multi-arc ion plating deposition equipment. The CrAl target current was set to 55~65 A, the argon flow rate was 180~220 sccm, the nitrogen flow rate was 500~700 sccm, the substrate bias was adjusted to -20~-30 V, and the deposition time was 110~130 min to achieve the deposition of a single-layer CrAlN coating.

[0020] Furthermore, the thickness of the CrAlN coating is 5-10 μm.

[0021] Furthermore, the step S5 is specifically as follows:

[0022] Under atmospheric pressure, the CrAlN coating is first gradually heated from room temperature to 60°C and then cooled to a low temperature of -20°C. The temperature error is controlled within ±2°C during the entire process. When the number of thermal cycles reaches 5 to 7, the temperature change is stopped and the coating is kept at a constant temperature for 10 to 14 hours.

[0023] Furthermore, the heating rate is 2°C / min, and the cooling rate is 1°C / min.

[0024] Furthermore, the matrix material is solid metal or alloy.

[0025] Furthermore, the test environment humidity of all coatings was always maintained at 80%, with a humidity deviation of ≤±2% RH.

[0026] The beneficial effects of the present invention are

[0027] This invention combines cyclic heat treatment with multi-arc ion plating technology, resulting in dislocation accumulation at the grain boundaries of the prepared CrAlN coating. This enhances internal stress at the grain boundaries, creating a stress-strain effect that increases the strength of the CrAlN coating, significantly improving its wear and corrosion resistance and service life. Furthermore, because the CrAlN coating is exposed to a humidity environment of approximately 80% RH during preparation and processing, a large amount of oxygen (in the form of Cr oxides, oxygen atoms, and oxygen ions) is present on and within the coating. This oxygen continuously participates in chemical reactions during friction, wear, and corrosion, producing Cr oxides. These oxides act as lubricants, enhancing the coating's wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a flow chart of a cyclic heat treatment method for a wear-resistant and corrosion-resistant CrAlN coating according to an embodiment of the present invention.

[0030] Figure 2 This is a cross-sectional SEM morphology image and a surface scanning EDS image of the single-layer CrAlN coating of Example 3.

[0031] Figure 3 3 is a friction coefficient curve and a corresponding wear rate diagram of the single-layer CrAlN coating in air and artificial seawater environments in Example 3.

[0032] Figure 4 This is a Raman spectrum diagram of the single-layer CrAlN coating after low-temperature cyclic heat treatment in Example 4 and a surface scanning EDS diagram of the cross section after treatment.

[0033] Figure 5 1 is a friction coefficient curve and a corresponding wear rate diagram of the single-layer CrAlN coating in Example 4 after low-temperature cyclic heat treatment in air and artificial seawater environments.

[0034] Figure 6 This is a cross-sectional SEM morphology image and Raman spectrum image of the multilayer Cr / CrAlN coating after low-temperature cyclic heat treatment in Example 5.

[0035] Figure 7 3. Friction coefficient curve and corresponding wear rate diagram of the multilayer Cr / CrAlN coating in Example 5 after low-temperature cyclic heat treatment in air and artificial seawater environments.

[0036] Figure 8 Figure 1 shows the polarization curves and electrochemical impedance spectroscopy of a multilayer Cr / CrAlN coating in a 3.5 wt% NaCl solution after low-temperature cyclic heat treatment. (Figure a shows the polarization curve of a multilayer Cr / CrAlN coating in a 3.5 wt% NaCl solution after low-temperature cyclic heat treatment, Figure b shows the Nyquist curve, and Figure c shows the Bode curve.) DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] like Figure 1As shown, the embodiment of the present invention provides a post-treatment method for improving the wear resistance and corrosion resistance of CrAlN coating. First, a Cr transition layer and a CrAlN coating are deposited by multi-arc ion plating technology, and then the coating is subjected to cyclic heat treatment. Specifically,

[0039] The present invention pre-treats the base material before starting the coating. All base materials are ultrasonically cleaned in acetone and anhydrous ethanol solutions for 15 to 25 minutes, and then blown dry with dry nitrogen.

[0040] The targets used in the coating process are metal Cr target and CrAl alloy target. The metal Cr target is used to deposit the Cr transition layer and the Cr single layer in the multi-layer Cr / CrAlN coating, and the CrAl alloy target is used to deposit the CrAlN layer. The pretreated substrate material is placed in the chamber, and then the chamber of the multi-arc ion plating deposition equipment is vacuumed (the vacuum degree is 4~6×10 -5 mbar), then, argon gas was passed into the chamber and maintained at 90~110 sccm. Deposition bias voltages of -850~-950 V, -1050~-1150 V, and -1151~-1250 V were selected to etch the substrate surface to remove the oxide layer and impurities.

[0041] Deposition bias voltages between -850 and -950 V, -1050 and -1150 V, and -1150 and -1250 V are used to etch the substrate surface, removing the oxide layer and impurities. The negative bias applied to the substrate provides energy to the plasma, accelerating its movement toward the substrate and bombarding it, improving deposition efficiency and film-substrate bonding. Increasing the negative bias voltage intensifies the plasma's micro-etching of the substrate surface, which helps improve film-substrate bonding. However, excessively high negative bias voltages can damage the substrate surface and affect surface roughness. Too low a negative bias voltage prevents this bombardment, preventing deposition of the coating and potentially damaging the substrate.

[0042] A certain thickness of metal Cr transition layer is pre-deposited before depositing the coating to improve the bonding strength between the film and the substrate.

[0043] The process for depositing a metallic Cr transition layer is as follows: A transition layer of a certain thickness is deposited on a pretreated substrate material, after which the oxide layer and impurities have been removed. The Cr target current is set to 50-70 A, the substrate bias voltage is -15--25 V, the argon flow rate is 180-220 sccm, and the deposition time is 8-12 minutes. This results in a metallic Cr transition layer being deposited on the substrate material.

[0044] The target current is selected between 50 A and -70 A. Although a target current that is too large can increase the deposition rate of the coating, it will lead to an increase in large particles on the coating surface, thereby reducing the erosion resistance of the coating. A target current that is too small will effectively reduce the size and number of particles on the coating surface, but will also reduce the deposition rate and hardness to a certain extent.

[0045] The process steps for preparing a single-layer CrAlN coating are as follows: using a multi-arc ion plating deposition equipment to deposit the CrAlN coating on the surface of a substrate on which a metal Cr transition layer has been deposited, setting the CrAl target current to 55~65 A, the argon flow rate to 180~220 sccm, the nitrogen flow rate to 500~700 sccm, the substrate bias voltage to -20~-30 V, and the deposition time to 110~130 min, a single-layer CrAlN coating can be deposited.

[0046] The substrate negative bias voltage should be between -20 V and -30 V. When the substrate negative bias voltage is low, the coating surface is prone to large particles and numerous defects. As the negative bias voltage increases, the number of large particles decreases, and the coating becomes denser. Excessive negative bias voltage can lead to defects such as pits.

[0047] In some embodiments, the multilayer Cr / CrAlN coating is prepared by alternately plating a single layer of Cr coating and a single layer of CrAlN coating, and the deposition time of the single layer of Cr coating and the single layer of CrAlN coating needs to be shortened to 2-3 minutes.

[0048] The material of the substrate is not limited, including solid metal or alloy, specifically, 316L stainless steel in this embodiment.

[0049] The thickness of the CrAlN coating is 5 μm to 10 μm.

[0050] In the field of surface engineering, coatings with both excellent mechanical properties and friction and corrosion resistance hold great potential as protective materials in harsh environments such as the ocean. This invention combines multi-arc ion plating with low-temperature thermal cycling treatment to significantly improve the coating's wear and corrosion resistance in low-temperature, high-humidity environments.

[0051] The cyclic heat treatment process is as follows: Under atmospheric pressure, the CrAlN coating is first gradually heated from room temperature to 60°C at a rate of 2°C / min, then cooled to a low temperature of -20°C. The cooling rate is 1°C / min, and the temperature error is controlled within ±2°C throughout the process. After 5 to 7 thermal cycles, the temperature change is stopped and the coating is kept at a constant temperature for 10 to 14 hours before the next thermal cycle. If the temperature range is increased, the internal stress generated in the coating during the heating and cooling stages will be excessive, which will not only cause deformation hardening but also reduce the bonding between the coating and the substrate, reduce the coating's hardness, and reduce the coating's wear and corrosion resistance.

[0052] The test environment humidity for all coatings of this invention was maintained at 80%, with a humidity deviation of ≤±2% RH. If the humidity is too low, too little oxygen is adsorbed on the coating surface and within it, and insufficient Cr oxide is generated during friction, thus affecting wear resistance. If the humidity is too high, the corrosion behavior of the coating is exacerbated, shortening the service life of the CrAlN coating.

[0053] Example 1

[0054] Step S1: pre-treating the base material, ultrasonically cleaning all the base materials in acetone and anhydrous ethanol solutions for 15 min, and then drying them with dry nitrogen.

[0055] Step S2: Place the pretreated substrate material in the chamber of the multi-arc ion plating deposition equipment and evacuate the chamber with a vacuum pump (the vacuum degree is 4×10 -5 mbar), then, argon gas was passed into the chamber and maintained at 90 sccm; deposition bias voltages of -850 V, -1050 V, and -1150 V were selected to etch the substrate surface to remove the oxide layer and impurities.

[0056] Step S3: Deposit a transition layer on the substrate material from which the oxide layer and impurities have been removed. Set the Cr target current to 50 A, the substrate bias voltage to -15 V, the argon gas flow rate to 180 sccm, and the deposition time to 12 min. Deposit a metallic Cr transition layer on the substrate material.

[0057] Step S4: Using a multi-arc ion plating deposition device, a CrAlN coating is deposited on the surface of the substrate material on which the metal Cr transition layer has been deposited. The CrAl target current is set to 55 A, the argon flow rate is 180 sccm, the nitrogen flow rate is 500 sccm, the substrate bias voltage is modulated to -20 V, and the deposition time is 130 min. A single-layer CrAlN coating can be deposited.

[0058] Step S5: Under atmospheric pressure, gradually heat the CrAlN coating from room temperature to 60°C at a rate of 2°C / min, then cool it to -20°C. The cooling rate is 1°C / min, and the temperature error is controlled within ±2°C throughout the entire process. After five thermal cycles, the temperature change is stopped and the coating is kept at a constant temperature for 10 hours.

[0059] Example 2

[0060] Step S1: pre-treating the base material, ultrasonically cleaning all the base materials in acetone and anhydrous ethanol solutions for 25 min, and then drying them with dry nitrogen.

[0061] Step S2: Place the pretreated substrate material in the chamber of the multi-arc ion plating deposition equipment and evacuate the chamber with a vacuum pump (6×10 -5 mbar), then, argon gas was passed into the chamber and maintained at 110 sccm; deposition bias voltages of -950 V, -1150 V, and -1250 V were selected to etch the substrate surface to remove the oxide layer and impurities.

[0062] Step S3: Deposit a transition layer on the substrate material from which the oxide layer and impurities have been removed. Set the Cr target current to 70 A, the substrate bias voltage to -25 V, the argon gas flow rate to 220 sccm, and the deposition time to 8 min. Deposit a metallic Cr transition layer on the substrate material.

[0063] Step S4: Using a multi-arc ion plating deposition device, a CrAlN coating is deposited on the surface of the substrate material on which the metal Cr transition layer has been deposited. The CrAl target current is set to 65 A, the argon flow rate is 220 sccm, the nitrogen flow rate is 700 sccm, the substrate bias voltage is modulated to -30 V, and the deposition time is 110 min. A single-layer CrAlN coating can be deposited.

[0064] Step S5: Under atmospheric pressure, gradually heat the CrAlN coating from room temperature to 60°C at a rate of 2°C / min, then cool it to -20°C. The cooling rate is 1°C / min, and the temperature error is controlled within ±2°C throughout the entire process. After seven thermal cycles, the temperature change is stopped and the coating is kept at a constant temperature for 14 hours.

[0065] Example 3

[0066] A transition Cr layer was deposited on a pretreated 316L stainless steel substrate using multi-arc ion plating. The targets used were a metallic Cr target and a CrAl alloy target. The metallic Cr target was used to deposit the Cr transition layer and the Cr single layer in the multilayer Cr / CrAlN coating, while the CrAl alloy target was used to deposit the CrAlN layer. Prior to coating, the chamber was evacuated using a vacuum pump (approximately 5×10 - 5 mbar), then argon was introduced into the chamber at a constant 100 sccm. Prior to deposition, the bias voltages were adjusted to -900 V, -1100 V, and -1200 V, respectively, to etch the substrate with Ar plasma to remove surface contaminants and oxide layers. For deposition of the transitional Cr layer, the Cr target current was 60 A, the substrate bias was -20 V, the argon flow rate was 200 sccm, and the deposition time was 10 min. The process parameters for depositing a single-layer CrAlN coating were: CrAl target current 60 A, argon flow rate of 200 sccm, nitrogen flow rate of 600 sccm, substrate bias of -25 V, and deposition time of 120 min.

[0067] Example 4

[0068] In this embodiment, the same multi-arc ion plating deposition technical parameters as in Example 3 were used to plate a single-layer CrAlN coating on a 316L stainless steel substrate.

[0069] Next, a low-temperature cyclic heat treatment was performed. Under atmospheric pressure, all coatings were gradually heated from room temperature to 60°C at a rate of 2°C / min, then cooled to a low temperature of -20°C. The cooling rate was 1°C / min, and the temperature error was controlled within ±2°C throughout the entire process. After six thermal cycles, the temperature was stopped and the coatings were kept at a constant temperature for 12 hours before the next cycle. The test environment humidity for all coatings was maintained at 80%.

[0070] Example 5

[0071] In this example, the same multi-arc ion plating deposition parameters as in Example 3 were used, except that the deposition time for the alternating Cr layer and the CrAlN layer was controlled to 2 minutes, and the alternating multilayer Cr / CrAlN coating was prepared by automatically switching the deposition modes. Subsequently, the multilayer Cr / CrAlN coating was treated using the same low-temperature cyclic heat treatment parameters as in Example 4.

[0072] Experimental Example 1

[0073] The cross-sectional SEM morphology and surface scanning EDS image of the CrAlN coating deposited by multi-arc ion plating in Example 3 are as follows: Figure 2As shown in Figure 2, the CrAlN coatings exhibit a relatively high density and a nearly defect-free structure. All coatings grow perpendicular to the substrate. This is due to the added Al atoms occupying the lattice sites of Cr atoms, resulting in lattice distortion and grain refinement. EDS results indicate that the atomic percentage of oxygen in the CrAlN coating is 2.5 at.%.

[0074] The friction and wear performance of the CrAlN coating of Example 3 was tested in atmospheric environment and seawater environment (load 5 N, frequency 5 Hz). Figure 3 As shown in the figure, the friction coefficients of the single-layer CrAlN coating in air and seawater environments are approximately 0.45 and 0.24, respectively, and the wear rate is: in air environment (CrAlN is approximately 11.2×10 -6 mm 3 •N -1 •m -1 ) and seawater environment (CrAlN is about 4.25×10 -6 mm 3 •N -1 •m -1 ).

[0075] Experimental Example 2

[0076] The Raman spectrum and cross-sectional EDS images of the single-layer CrAlN coating subjected to low temperature thermal cycling treatment obtained in Example 4 are shown in FIG. Figure 4 As shown in Figure 2, Raman spectroscopy and cross-sectional EDS results indicate that the oxygen content of the single-layer CrAlN coating was 2.5 at.% before low-temperature thermal cycling. After alternating high- and low-temperature thermal cycling, the oxygen atomic percentage in the single-layer CrAlN coating increased to 4.2 at.%, indicating the presence of adsorbed molecules within the coating. Compared to the as-deposited CrAlN coating, after low-temperature thermal cycling, oxygen was found to be located in defects such as pores and pinholes within the CrAlN coating. O was distributed in the treated CrAlN coating as Cr oxides or ions. Raman spectroscopy results confirm the formation of a certain amount of Cr oxide, which acts as a lubricant and effectively reduces the friction coefficient. This is also a key reason for the improved tribological performance of the single-layer CrAlN coating after low-temperature thermal cycling.

[0077] The friction and wear performance of the single-layer CrAlN coating treated with low-temperature thermal cycling in Example 4 was tested in atmospheric environment and seawater environment (load 5 N, frequency 5 Hz). Figure 5As shown in Figure 2, the friction coefficients of the single-layer CrAlN coating in air and seawater environments are approximately 0.41 and 0.22, respectively, and the wear rate is: in air environment (CrAlN is approximately 10.5×10 - 6 mm 3 •N -1 •m -1 ) and seawater environment (CrAlN is about 4.37×10 -6 mm 3 •N -1 •m -1 ), the overall tribological properties of the coating have been improved to a certain extent.

[0078] Experimental Example 3

[0079] The cross-sectional SEM morphology and Raman spectrum of the multilayer Cr / CrAlN coating after low temperature cycle heat treatment obtained in Example 5 are shown in FIG. Figure 6 As shown in the figure, the multilayer Cr / CrAlN coating shows alternating and continuous growth of Cr and CrAlN layers. The multilayer Cr / CrAlN coating also exhibits a terraced structure with uniform thickness. The multilayer Cr / CrAlN coating exhibits a denser structure, which is due to the alternation of Cr and CrAlN layers. The high degree of interface overlap between the Cr layered structure and the stainless steel substrate effectively reduces the internal stress of the coating, thereby improving the adhesion between the substrate and the coating. Raman spectroscopy results indicate that the oxygen content in the multilayer Cr / CrAlN coating increases, and the oxygen element is distributed in the treated Cr / CrAlN coating in the form of Cr oxides or ions. As a lubricant, O can effectively improve the tribological properties of the multilayer Cr / CrAlN coating.

[0080] The friction and wear performance of the multilayer Cr / CrAlN coating obtained in Example 5 after low temperature cycle heat treatment was tested in atmospheric environment and seawater environment (load 5 N, frequency 5 Hz). Figure 7 As shown in the figure, the friction coefficients of the single-layer CrAlN coating in air and seawater environments are approximately 0.35 and 0.18, respectively, and the wear rate is: in air environment (CrAlN is approximately 5.74×10 -6 mm 3 •N -1 •m -1 ) and seawater environment (CrAlN is about 3.23×10 -6 mm 3 •N -1 •m -1 ), the wear resistance of the coating is greatly improved.

[0081] Figure 8The polarization curve and electrochemical impedance spectrum of the multilayer Cr / CrAlN coating in 3.5 wt.% NaCl solution after low-temperature cyclic heat treatment are shown. The corrosion potential and corrosion current density of the coating can be used to roughly determine the corrosion resistance of the coating. Generally speaking, the smaller the corrosion current density of the coating and the higher the corrosion potential, the better the corrosion resistance of the coating. From the polarization curve, it can be seen that the corrosion potential and corrosion current density of the multilayer Cr / CrAlN coating are -0.26 V, and the polarization current density is 8.2×10 -7 A / cm 2 On the other hand, the EIS impedance spectrum of the coating in the corrosive medium can also be used to roughly determine the corrosion resistance of the coating. The Nyquist and Bode curves of the Cr / CrAlN coating after low-temperature thermal cycling clearly show that it also has a high impedance modulus value at low frequencies. This is mainly because the high-humidity and low-temperature cyclic heat treatment causes the accumulation of dislocations within the coating, which can effectively slow down the intrusion of the corrosive medium. This significantly improves the corrosion resistance of the coating.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A post-treatment method for improving the wear resistance and corrosion resistance of CrAlN coating, characterized in that: The following steps are involved: Step S1: pre-treating the base material; Step S2: etching the surface of the base material to remove the oxide layer and impurities; Step S3, depositing a metal Cr transition layer on the base material; Step S4: depositing a CrAlN coating on the metal Cr transition layer; Step S5: performing cyclic heat treatment on the base material on which the CrAlN coating is deposited; The step S2 specifically comprises: placing the pretreated substrate material in a chamber of a multi-arc ion plating deposition equipment and performing a vacuum treatment, then passing argon gas into the chamber and maintaining it at 90-110 sccm, and selecting deposition bias voltages of -850-950 V, -1050-1150 V, and -1151 V-1250 V, respectively, to etch the surface of the substrate material to remove the oxide layer and impurities; The step S3 specifically comprises: depositing a transition layer on the substrate material from which the oxide layer and impurities have been removed, setting the Cr target current to 50-70 A, the substrate bias voltage to -15-25 V, the argon gas flow rate to 180-220 sccm, and the deposition time to 8-12 min, to deposit a metal Cr transition layer on the substrate material; The step S4 specifically comprises: using a multi-arc ion plating deposition device to deposit a CrAlN coating on the surface of the substrate material on which the metal Cr transition layer has been deposited, setting the CrAl target current to 55-65 A, the argon flow rate to 180-220 sccm, the nitrogen flow rate to 500-700 sccm, the substrate bias voltage to -20--30 V, and the deposition time to 110-130 min to deposit a single-layer CrAlN coating, and alternately plating a single-layer Cr coating and a single-layer CrAlN coating to achieve the preparation of a multilayer Cr / CrAlN coating; Specifically, step S5 includes: under atmospheric pressure, gradually heating the CrAlN coating from room temperature to 60°C, and then cooling it to a low temperature of -20°C. During the entire process, the temperature error is controlled within ±2°C. When the number of thermal cycles reaches 5 to 7, the temperature change is stopped, and the coating is kept at a constant temperature for 10 to 14 hours. The heating rate is 2°C / min, and the cooling rate is 1°C / min. The test environment humidity of all coatings is always maintained at 80%, and the humidity deviation is ≤±2%RH.

2. A post-treatment method for improving the wear resistance and corrosion resistance of CrAlN coating according to claim 1, characterized in that: The step S1 is specifically as follows: All matrix materials were ultrasonically cleaned in acetone and anhydrous ethanol solutions for 15 min to 25 min, and then dried with dry nitrogen.

3. The post-treatment method for improving the wear resistance and corrosion resistance of CrAlN coating according to claim 1, characterized in that: The thickness of the CrAlN coating is 5 μm to 10 μm.

4. The post-treatment method for improving the wear resistance and corrosion resistance of CrAlN coating according to claim 1, characterized in that: The matrix material is solid metal or alloy.

Images