Coating, method for preparing coating on alloy substrate, and alloy component

Abstract

A method for preparing a coating on an alloy substrate comprises subjecting a surface of the alloy substrate to a shot peening treatment using a high-pressure water jet, a sand blasting treatment, and

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of surface treatment of metal materials, and in particular to a coating, a method for preparing the coating on an alloy substrate, and an alloy component. BACKGROUND

[0002] Fretting wear refers to the wear of two contacting surfaces due to relatively low-amplitude oscillatory motion, and is a recurring problem in industrial production. The seizure, power loss, noise increase, size change, material loss, and even breakage of key components in the high-end equipment (such as aircraft engines, automobiles, ships, high-speed railways, and power lines) due to high-frequency vibration are all caused by the fretting wear. Therefore, the fretting wear is commonly known as "industrial cancer" internationally. As a result, it is crucial to improve the service reliability and service life of key components in high-end equipment by improving the resistance of metal parts to fretting damage and wear. Surface modification, surface coating, and increased lubrication of parts are effective ways to solve the fretting wear of components, and commonly used methods include adding liquid lubricants, surface work hardening, and surface hard coating. The surface hard coating has outstanding chemical stability, high mechanical strength, and excellent wear resistance. Accordingly, coating the surface of parts with hard coating becomes an important means to improve the surface resistance of metal components to fretting wear.

[0003] Desirable bonding between the coating and the substrate is the basic condition for functioning. A coating that does not adhere well to the substrate is almost always of poor quality. Moreover, since extremely thin of the coating, if the adhesion force is not high enough, and the coating is easy to fall off, the continuous use of the coating could not be guaranteed. In summary, whether a coating is used as an electronic circuit coating, decorative coating, protective coating, or industrial wear-resistant coating, sufficiently strong interface bonding strength is an important factor in ensuring durability of the coating. However, a metallurgical bonding interface could not be formed between most coatings and substrates, making it difficult to significantly improve the fretting wear performance of parts. In view of this, it is difficult for single or composite coatings to achieve ultra-long service life under changing fretting parameters. In order to obtain a coating with a strong metallurgical bond, high-temperature and high-pressure technologies are required. However, on one hand, the mechanical properties of the substrate may be significantly reduced under high temperature and high pressure, and on the other hand, an expansion coefficient of the coating is greatly different from that of an alloy, and thus cooling from high temperature to room temperature would lead to the coating being easy to crack and peel off from the substrate, thus greatly reducing a service life of the friction pair or even causing failure.

[0004] Therefore, it has become a technical problem that needs to be solved urgently in this field to provide a surface treatment method for providing a high-fretting wear-resistant alloy component (also a method for preparing a coating on an alloy substrate), so as to form a high-wear-resistant coating with a high bonding force on the surface of alloy substrates. SUMMARY

[0005] An object of the present disclosure is to provide a coating, a method for preparing the coating on an alloy substrate, and an alloy component. In the present disclosure, the method allows for the formation of a high-wear-resistant coating on a surface of the alloy substrate to impart desirable mechanical properties to the alloy component, and results in a high bonding force between the high-wear-resistant coating and an alloy substrate, such that the obtained alloy component exhibits excellent fretting wear resistance.

[0006] To achieve the above object, the present disclosure provides the following technical solutions:

[0007] The present disclosure provides a method for preparing a coating on an alloy substrate, including the following steps:

[0008] (1) subjecting a surface of an alloy substrate to shot peening treatment with high-pressure water jet, sand blasting treatment, and surface corrosion treatment in sequence, to obtain a surface-pretreated alloy component; and

[0009] (2) subjecting the surface-pretreated alloy component obtained in step (1) to magnetron sputtering chromium plating and plasma nitridation in sequence, to obtain the coating on the alloy substrate.

[0010] In some embodiments, the shot peening treatment with high-pressure waterjet in step (1) is conducted with parameters including: an abrasive used in a water jet being a steel shot; a jet pressure of 20 MPa to 120 MPa; a nozzle feed speed of 5 mm / min to 20 mm / min; a jet-to-target distance of 5 mm to 15 mm; and a jet angle of 85° to 95°.

[0011] In some embodiments, a product obtained from the shot peening treatment with high-pressure water jet in step (1) has surface modification parameters including: a surface roughness Ra of 0.8 gm to 2.5 gm; a surface residual stress of -600 MPa to -1,000 MPa; a surface modification layer depth of 60 pm to 120 pm; and a grain size of 20 nm to 100 nm within a modification layer depth of 0 pm to 30 pm.

[0012] In some embodiments, a product obtained from the sand blasting treatment in step (1) has a surface roughness Ra of 0.8 pm to 2.5 pm.

[0013] In some embodiments, the surface corrosion treatment in step (1) is conducted with a solution of nitric acid in alcohol for 10 s to 120 s.

[0014] In some embodiments, the alloy substrate in step (1) is selected from the group consisting of a low-alloy low-medium-carbon alloy steel and a stainless steel.

[0015] In some embodiments, the magnetron sputtering chromium plating in step (2) is conducted with parameters including: a target-to-substrate distance of 8 cm to 12 cm; a vacuum degree of 5x1 O'4 Pa to 5xl0'3 Pa; and a chromium plating power of 80 W to 150 W; a chromium plating temperature of 100 °C to 400 °C; and a chromium plating time of 4 h to 8 h.

[0016] In some embodiments, the plasma nitridation in step (2) is conducted with parameters including: a nitridation atmosphere being NH3 or a mixture of NH3 and argon; a nitridation temperature of at 450 °C to 520 °C; a nitridation voltage of 580 V to 720 V; a nitridation pressure of 200 Pa to 450 Pa; and a nitridation time of 7 h to 12 h.

[0017] The present disclosure further provides the coating prepared by the method as described in the above technical solutions, including an interface inter-miscible layer and a CrNx layer, which are attached to a surface of the alloy substrate in sequence.

[0018] In some embodiments, the interface inter-miscible layer has a thickness of 0.5 pm to 2 pm, and the CrNx layer has a thickness of 2 pm to 5 pm.

[0019] The present disclosure also provides an alloy component, including an alloy substrate; and the coating as described in the above technical solutions that is attached onto a surface of the alloy substrate.

[0020] The present disclosure provides a method for preparing a high-wear-resistant coating, including the following steps: subjecting a surface of an alloy substrate to shot peening treatment with high-pressure waterjet, sand blasting treatment, and surface corrosion treatment in sequence, to obtain a surface-pretreated alloy component; and subjecting the surface-pretreated alloy component to magnetron sputtering chromium plating and plasma nitridation in sequence, to obtain the high-wear-resistant alloy component. In the present disclosure, the surface of the alloy substrate is sequentially subjected to shot peening treatment with high-pressure water jet, sand blasting treatment, and surface corrosion treatment, which could endow the alloy surface with a certain shot peening depth, roughness, and cleanliness, and is more conducive to the mutual solid solution of elements in the wear-resistant coating, thereby firmly bonding to the surface of the alloy substrate. The magnetron sputtering chromium plating and plasma nitridation are sequentially conducted. On one hand, a Cr layer formed earlier and the alloy substrate elements diffuse with each other, such that a composition gradient change is formed at the interface, thereby generating an atomic-level mixing or alloying at the interface, which could effectively improve the bonding force between the wear-resistant coating and the substrate. On the other hand, the N element introduced by ion nitridation has a strong bonding ability with Cr atoms, and under the action of high N potential, accompanying the penetration of N atoms to the inner of the substrate, Cr atoms are also drawn into the substrate through mutual diffusion to generate CrNx, thereby forming an interface inter-miscible layer with substrate elements + CrNx and a CrNx layer on the surface of the substrate in sequence, thereby achieving a firm metallurgical bonding between the coating and the substrate. In addition, due to high surface hardness and low friction coefficient, the CrNx could exert an excellent wear-resistance and is more suitable for fretting wear conditions, thus effectively extending the service life of parts.

[0021] The results of the examples show that, as verified by a fretting wear test, a 40CrNiMo steel of Comparative Example 1 has a wear depth of as high as 15.66 pm to 17.2 pm without any surface treatment. In contrast, the high-wear-resistant coating samples in Examples 1 to 9 obtained by the method according to the present disclosure have a wear depth of only 0 pm to 6.14 pm, which is significantly lower than that of the 40CrNiMo steel in Comparative Example 1 without any surface treatment. These results show that the high-wear-resistant alloy obtained by the method shows excellent wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 shows a scanning electron microscopy (SEM) image of a surface coating structure of the high-wear-resistant alloy component prepared in Example 1 of the present disclosure.

[0023] FIG. 2 shows an SEM image of longitudinal structure of the surface coating of the high-wear-resistant alloy component prepared in Example 1 of the present disclosure.

[0024] FIG. 3A to FIG. 3C show energy spectra of element distribution of the longitudinal structure of the surface coating of the high-wear-resistant alloy component prepared in Example 1 of the present disclosure, in which, FIG. 3A shows an energy spectrum diagram of the overall element distribution of the coating, FIG. 3B shows an energy spectrum diagram of the element distribution of a CrNx layer region of FIG. 3 A, and FIG. 3C shows an energy spectrum diagram of the element distribution of an interface inter-miscible layer region of FIG. 3 A.

[0025] FIG. 4 shows an SEM image of a surface coating structure of the high-wear-resistant alloy component prepared in Example 3 of the present disclosure.

[0026] FIG. 5 shows an SEM image of longitudinal structure of the surface coating of the high-wear-resistant alloy component prepared in Example 3 of the present disclosure.

[0027] FIG. 6Ato FIG. 6C show energy spectra of element distribution of longitudinal structure of the surface coating of the high-wear-resistant alloy component prepared in Example 3 of the present disclosure, in which, FIG. 6A shows an energy spectrum diagram of the overall element distribution of the coating, FIG. 6B shows an energy spectrum diagram of the element distribution of a CrNx layer region of FIG. 6A, and FIG. 6C shows an energy spectrum diagram of the element distribution of an interface inter-miscible layer region of FIG. 6A.

[0028] FIG. 7A to FIG. 7C show an element interaction diagram of Cr element and substrate elements in the interface inter-miscible layer structure in the surface coating of the high-wear-resistant alloy component prepared in Example 3 of the present disclosure, in which, FIG. 7A corresponds to Cr element and Fe element; FIG. 7B corresponds to N element; and FIG. 7C corresponds to Ni element.

[0029] FIG. 8 shows a scratch appearance diagram of the surface coating of the high-wear-resistant alloy component prepared in Example 1 of the present disclosure after being subjected to a micron scratch bonding test.

[0030] FIG. 9 shows a relationship between the actual load and friction force obtained by the micron scratch bonding test of the surface coating of the high-wear-resistant alloy component prepared in Example I of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present disclosure provides a surface treatment method of a high-wear-resistant alloy component (i.e., a method for preparing a coating on an alloy substrate), including the following steps:

[0032] (1) subjecting a surface of an alloy substrate to be treated to shot peening treatment with high-pressure water jet, sand blasting treatment, and surface corrosion treatment in sequence, to obtain a surface-pretreated alloy component; and

[0033] (2) subjecting the surface-pretreated alloy component obtained in step (1) to magnetron sputtering chromium plating and plasma nitridation in sequence, to obtain the high-wear-resistant alloy component.

[0034] In the present disclosure, a surface of an alloy substrate to be treated is subjected to shot peening treatment with high-pressure water jet, sand blasting treatment, and surface corrosion treatment in sequence, to obtain a surface-pretreated alloy component.

[0035] In some embodiments of the present disclosure, the alloy substrate to be treated is selected from the group consisting of a low-alloy low-medium-carbon alloy steel and a stainless steel. In some embodiment, the low-alloy low-medium-carbon alloy steel includes 40CrNiMo, 20CrNiMoA, 23CrNi3Mo, or 40CrMnMo. In some embodiment, the stainless steel includes 304 stainless steel or austenitic stainless steel.

[0036] In some embodiments of the present disclosure, the shot peening treatment with high-pressure water jet is conducted with parameters including: an abrasive used in a water jet being a steel shot; a jet pressure of 20 MPa to 120 MPa; a nozzle feed speed of 5 mm / min to 20 mm / min; a jet-to-target distance of 5 mm to 15 mm; and a jet angle of 85° to 95°, more preferably conducted with parameters as follows: an abrasive used in a waterjet being a steel shot; a jet pressure of 40 MPa to 80 MPa; a nozzle feed speed of 5 mm / min to 10 mm / min; a jet-to-target distance of 6 mm to 10 mm, and a jet angle of 90°. By controlling the parameters of shot peening treatment with high-pressure waterjet within the above range, a certain roughness and depth of the modified layer could be achieved on the surface of the alloy substrate to be treated, which is more conducive to a higher bonding force between the alloy substrate and the wear-resistant layer formed in the subsequent steps.

[0037] In some embodiments of the present disclosure, a product obtained from the shot peening treatment with high-pressure water jet has surface modification parameters including: a surface roughness Ra of 0.8 pm to 2.5 pm; a surface residual stress of -600 MPa to -1,000 MPa; a surface modification layer depth of 60 pm to 120 pm; and a grain size of 20 nm to 100 nm within a modification layer depth of 0 pm to 30 pm. Controlling the surface modification parameters of the product obtained from shot peening treatment with high-pressure waterjet within the above range is more conducive to a high bonding force between the alloy component substrate and the wear-resistant coating formed in the subsequent steps.

[0038] In the present disclosure, there is no special requirement for specific operations of the sand blasting treatment, as long as it could ensure that the product obtained from sand blasting treatment has a surface roughness Ra within the required range.

[0039] In some embodiments of the present disclosure, the product obtained from sand blasting treatment has a surface roughness Ra of 0.8 pm to 2.5 pm.

[0040] In some embodiments of the present disclosure, the product of the sand blasting treatment is subjected to first ultrasonic cleaning and drying in sequence. There are no special requirements for the specific operations of the first ultrasonic cleaning and drying, and operations well known in the art may be used to ensure that the surface of the alloy substrate after sand blasting treatment has high cleanliness.

[0041] In some embodiments of the present disclosure, the surface corrosion treatment is conducted with a solution of nitric acid in alcohol for preferably 10 s to 120 s. In some embodiments, nitric acid in the solution of nitric acid in alcohol has a volume concentration of 3% to 5%, and preferably 4%. There is no special requirement for a concentration of ethanol in the solution of nitric acid in alcohol, as long as the concentration of nitric acid therein is within the required range. By controlling the parameters of the surface corrosion treatment within the above range, an oxide layer on the surface of the alloy substrate could be removed, which is more conducive to high bonding force between the alloy component substrate and the wear-resistant coating formed in subsequent steps.

[0042] In some embodiments of the present disclosure, the product obtained from the surface corrosion treatment is subjected to second ultrasonic cleaning and drying in sequence. There are no special requirements for specific operations of the second ultrasonic cleaning and drying, and operations well known in the art may be used to ensure that a corrosion liquid remaining on the surface of the alloy component after the surface corrosion treatment is fully removed.

[0043] In the present disclosure, the surface-pretreated alloy component is subjected to magnetron sputtering chromium plating and plasma nitridation in sequence, to obtain the high-wear-resistant alloy component.

[0044] In some embodiments of the present disclosure, high-voltage magnetron sputtering cleaning is conducted before the magnetron sputtering chromium plating. In some embodiments, the high-voltage magnetron sputtering cleaning is conducted at a negative bias voltage of -600 V to -800 V, and preferably -700 V. By controlling the negative voltage of high-voltage magnetron sputtering cleaning within the above range, it ensures high cleanliness of the equipment cavity and the alloy surface, and is more conducive to obtaining a higher bonding force between the subsequent wear-resistant coating and the alloy substrate.

[0045] In some embodiments of the present disclosure, the magnetron sputtering chromium plating is conducted with parameters including: a target-to-substrate distance of 8 cm to 12 cm; a vacuum degree of 5*10'4 Pa to 5*10’3 Pa; and a chromium plating power of 80 W to 150 W; a chromium plating temperature of 100 °C to 400 °C; and a chromium plating time of 4 h to 8 h; and preferably with parameters as follows: a target-to-substrate distance of 9 cm to 11 cm, a vacuum degree of 5.5* 10'4 Pa to 4.5xl0'3 Pa, and a chromium plating power of 90 W to 140 W, a chromium plating temperature of 200 °C to 300 °C, and a chromium plating time of 5 h to 7 h. Controlling the parameters of magnetron sputtering chromium plating within the above range is more conducive to obtaining a uniform chromium plating layer, allowing Cr to penetrate deeper into the alloy component substrate to form an inter-miscible interface containing Cr, which is more conducive to achieving metallurgical bonding between the high-wear-resistant coating and the surface of the alloy component.

[0046] In other embodiments of the present disclosure, parameters of the magnetron sputtering chromium plating further includes: a negative bias voltage of -60 V to -120 V. When a negative bias is applied during the magnetron sputtering chromium plating, the magnetron sputtering chromium plating could be assisted, which is more conducive to maintaining a high deposition rate of Cr to bombard the surface of the alloy substrate. Thus, Cr atoms could penetrate into the surface layer of the alloy substrate to achieve metallurgical bonding, which is more conducive to improving the bonding force between the wear-resistant coating and the alloy substrate.

[0047] In some embodiments of the present disclosure, an auxiliary gas for the magnetron sputtering chromium plating is argon. In some embodiments, the auxiliary gas has a pressure of 0.6 Pa. In the present disclosure, argon is used as an auxiliary gas and a pressure of the argon is controlled within the above range, such that ionized Ar could bombard the target surface with high energy, and Cr could have sufficient kinetic energy to be deposited on the surface of the alloy substrate and diffuse with the alloy substrate elements. This is more conducive to achieving metallurgical bonding between the wear-resistant layer and the substrate.

[0048] In some embodiments of the present disclosure, a target material for the magnetron sputtering chromium plating is a Cr target.

[0049] In some embodiments of the present disclosure, a cooling means for the magnetron sputtering chromium plating includes cooling with furnace to not greater than 60 °C, taking out of the furnace, and air cooling to room temperature.

[0050] In some embodiments of the present disclosure, the plasma nitridation is conducted with parameters including: a nitridation atmosphere being NH3 or a mixture of NH3 and argon; a nitridation temperature of 450 °C to 520 °C; a nitridation voltage of 580 V to 720 V; and a nitridation pressure of 200 Pa to 450 Pa; and a nitridation time of 7 h to 12 h. Controlling the parameters of plasma nitridation within the above range allows the N element to quickly penetrate into inner of the substrate in the action of high N potential, and generate CrNx with the Cr that enters the surface of the alloy substrate by magnetron sputtering, thereby forming an interface layer where the substrate, substrate elements, and CrNx are mutually dissolved, as well as a CrNx layer on the substrate surface in sequence. This is more conducive to improving the bonding force between the wear-resistant coating and the alloy component substrate, such that the alloy component is endowed with high resistance to fretting wear.

[0051] In some embodiments of the present disclosure, under the condition that the nitridation atmosphere is NH3, the NH3 has a flow rate of 0.7 L / min to 0.8 L / min, and preferably 0.72 L / min. By controlling the flow rate of NH3 within the above range, it is more conducive to rapid nitridation and formation of a uniform CrNx layer.

[0052] In some embodiments of the present disclosure, under the condition that the nitridation atmosphere is a mixture of NH3 and argon, a flow ratio of NH3 to argon is 5:1. In some embodiments, the NH3 has a flow rate of 0.4 L / min to 0.6 L / min, and preferably 0.5 L / min. Adding argon to the nitrogen source could not only increase the nitridation rate but also significantly reduce the nitridation voltage.

[0053] In some embodiments of the present disclosure, a circulating water system is used to maintain a constant nitridation temperature of the plasma nitridation. There are no special requirements for specific composition and operation means of the circulating water system, as long as the constant nitridation temperature could be ensured.

[0054] In some embodiments of the present disclosure, a cooling means of the plasma nitridation is furnace cooling to room temperature.

[0055] In some embodiments of the present disclosure, after the plasma nitridation is completed, the product obtained by the plasma nitridation is subjected to magnetron sputtering silver plating, or grease coating, or the magnetron sputtering silver plating and the grease coating in sequence. In some embodiments, the magnetron sputtering silver plating is conducted at a power of 80 W to 120 W for preferably 1.5 h to 2.5 h. There are no special requirements for the specific operation of grease coating, as long as the thickness of a grease layer obtained by the grease coating is ensured to be within the appropriate film thickness. By the above operations on the product obtained by plasma nitridation, one or both of the silver layer and the grease layer could continue to be formed on the surface of the coating formed by plasma nitridation, such that the high-wear-resistant coating could have high lubrication performance and a lower friction coefficient. Moreover, the prepared high-wear-resistant alloy component and a component used in conjunction with it could achieve lower wear loss, thereby improving the overall wear resistance and service life of the product.

[0056] In some embodiments of the present disclosure, a grease used for the grease coating includes the following components: solid grease, perfluoropoly ether (PFPE), a thickener, and polytetrafluoroethylene (PTFE). In some embodiments, a mass fraction of the PFPE is 70% to 75%. By using the grease with the above composition, a protective layer could be formed on the surface of the high-wear-resistant alloy component, thus reducing the surface friction coefficient of the high-wear-resistant alloy, making the interface of the friction pair more lubricated, reducing the wear loss of the friction pair, and thereby increasing the service life of the friction pair.

[0057] In the present disclosure, the wear-resistant coating on the surface of the high-wear-resistant alloy component obtained by the surface treatment method has a high bonding force with the alloy substrate, such that the wear-resistant alloy component has a higher hardness and excellent wear resistance.

[0058] The present disclosure further provides a high-wear-resistant alloy coating obtained by the surface treatment method, including an alloy substrate as well as an interface inter-miscible layer of substrate elements and CrNx, and a CrNx layer that are attached to a surface of the alloy substrate in sequence.

[0059] In some embodiments of the present disclosure, the interface inter-miscible layer has a thickness of 0.5 pun to 2 pm, and the CrNx layer has a thickness of preferably 2 pm to 5 pm. Controlling the thicknesses of both the interface inter-miscible layer and the CrNx layer within the above range is more conducive to endowing the alloy component with higher hardness and wear resistance.

[0060] In some embodiments of the present disclosure, after the plasma nitridation is completed, under the condition that the product obtained from the plasma nitridation is also subjected to magnetron sputtering silver plating, the high-wear-resistant alloy includes an alloy substrate, as well as an interface inter-miscible layer, a CrNx layer, and a silver layer that are attached to a surface of the alloy substrate in sequence.

[0061] In some embodiments of the present disclosure, after the plasma nitridation is completed, under the condition that the product obtained from the plasma nitridation is also subjected to grease coating, the high-wear-resistant alloy includes an alloy substrate, as well as an interface inter-miscible layer, a CrNx layer, and a grease layer that are attached to a surface of the alloy substrate in sequence.

[0062] In some embodiments of the present disclosure, after the plasma nitridation is completed, under the condition that the product obtained from the plasma nitridation is also subjected to magnetron sputtering silver plating and grease coating in sequence, the high-wear-resistant alloy includes an alloy substrate, as well as an interface inter-miscible layer, a CrNx layer, a silver layer, and a grease layer that are attached to a surface of the alloy substrate in sequence.

[0063] In some embodiments of the present disclosure, the silver layer has a thickness of independently 1 pm to 3 pm. There is no special requirement for a thickness of the grease layer, as long as it could ensure that the grease layer plays a desirable protective role. Controlling the thickness of the silver layer within the above range and adding the grease layer is more conducive to improving the wear resistance of the high-wear-resistant alloy, thereby achieving a longer service life when being used in fretting wear conditions.

[0064] In the present disclosure, the high-wear-resistant alloy component has a wear-resistant coating with uniform structure and thickness, and the high-wear-resistant alloy component shows higher hardness and greater wear resistance, which are more suitable for fretting wear conditions.

[0065] The technical solutions of the present disclosure will be clearly and completely described below with reference to the examples of the present disclosure. Apparently, the described examples are merely a part rather than all of the examples of the present disclosure. All other examples obtained by those skilled in the art based on the examples of the present disclosure without creative efforts shall fall within the scope of the present disclosure.

[0066] Example 1

[0067] A surface treatment method of an alloy was performed / a high-wear-resistant alloy component was provided according to the following procedures:

[0068] (1) A surface of an alloy substrate was subjected to shot peening treatment with high-pressure water jet, sand blasting treatment, a first ultrasonic cleaning and drying, surface corrosion treatment, a second ultrasonic cleaning and drying in sequence, to obtain a surface-pretreated alloy component. Specifically, a low-alloy low-medium-carbon alloy steel 40CrNiMo was selected as the alloy substrate, and parameters of the shot peening treatment with high-pressure waterjet were set to conduct the shot peening treatment with high-pressure waterjet, and then the sand blasting treatment was conducted such that a surface roughness Ra of a product obtained by the sand blasting treatment was 1.8 pm. The product obtained by the sand blasting treatment was subjected to the first ultrasonic cleaning with anhydrous ethanol for 15 min, dried with a hair dryer, and then subjected to surface corrosion treatment, wherein the surface corrosion treatment was conducted using a solution of nitric acid in alcohol with a nitric acid volume concentration of 4% for 60 s. Finally, an obtained product was subjected to the second ultrasonic cleaning for 15 min and dried with the hair dryer to obtain the surface-pretreated alloy component, wherein the specific process parameters of the shot peening treatment with high-pressure waterjet and the surface modification parameters of the obtained product are shown in Table 1.

[0069] (2) The surface-pretreated alloy component obtained in step (1) was subjected to magnetron sputtering cleaning, magnetron sputtering chromium plating, and plasma nitridation in sequence, to obtain the high-wear-resistant alloy component; specifically,

[0070] the surface-pretreated alloy component obtained in step (1) was placed into a magnetron sputtering chamber through a fixture, a Cr target was loaded into the sputtering chamber, where a distance between the Cr target and the surface of the metal substrate to be sputtered was adjusted to 8 cm, and the chamber was evacuated to a vacuum degree of 6* 10"4 Pa; argon was introduced into the chamber and a gas pressure of the argon was adjusted to 2 Pa, a negative bias voltage was set to -700 V, a substrate baffle was opened, and high-voltage magnetron sputtering cleaning was conducted at a voltage of -700 V for 30 min, and the high-voltage magnetron sputtering cleaning was terminated; the Cr target was used as a target material for magnetron sputtering chromium plating, substrate stage rotation was started, where a substrate stage rotation speed was set to 15 r / min, a power supply was a DC power supply, a target-to-substrate-distance was 8 cm, a vacuum degree was 6*10'4 Pa, a pressure of the auxiliary gas argon in chamber was adjusted to 0.6 Pa, a chromium plating temperature was set to 300 °C, a chromium plating power was set to 100 W, a Cr target baffle was opened, and the magnetron sputtering for forming Cr layer was conducted for 6 h. After the magnetron sputtering chromium plating was completed, the DC power supply and heating device were turned off, and Cr target baffle and substrate baffle were closed. When the chamber temperature dropped to 60 °C or lower, the chrome-plated alloy was taken out from the chamber.

[0071] A circulating water system was turned on, the chrome-plated alloy was placed in a plasma nitridation chamber, a valve on a furnace body was tightened, a valve under the furnace body was opened, and a mechanical pump was started to evacuate to a vacuum degree of not greater than 15 Pa; a plasma nitridation control panel was started, wherein a nitridation atmosphere was NH\ a flow rate of NH3 was 0.72 L / min, a nitridation temperature was set to 490 °C, a nitridation voltage was 710 V, a gas pressure was 220 Pa, and a nitridation time was 10 h; after the plasma nitridation was completed, the power supply and the circulating water system were turned off; and after cooling to room temperature, the alloy after plasma nitridation was taken out, to obtain the high-wear-resistant alloy component.

[0072] The high-wear-resistant alloy component prepared by the above method was composed of an alloy substrate, as well as an interface inter-miscible layer and a CrNx layer that were attached to a surface of the alloy substrate in sequence, wherein the alloy substrate was the low-alloy low-medium-carbon alloy steel 40CrNiMo, and thicknesses of the interface inter-miscible layer and the CrNx layer are shown in Table 2.

[0073] Example 2

[0074] This example was performed according to procedures as described in Example 1, except that: after plasma nitridation in step (2), conventional magnetron sputtering silver plating was conducted for 2 h at a silver plating power of 100 W.

[0075] The high-wear-resistant alloy component prepared by the above method was composed of an alloy substrate, as well as an interface inter-miscible layer, a CrNx layer, and a silver layer that were attached to a surface of the alloy substrate in sequence, wherein the alloy substrate was the low-alloy low-medium-carbon alloy steel 40CrNiMo, and thicknesses of the interface inter-miscible layer, the CrNx layer, and the silver layer are shown in Table 2.

[0076] Example 3

[0077] This example was performed according to procedures as described in Example 1, except that: in step (1), during the magnetron sputtering chromium plating, a negative bias voltage of -100 V was applied and maintained throughout the sputtering; and the magnetron sputtering chromium plating was conducted for 7 h.

[0078] The high-wear-resistant alloy component prepared by the above method was composed of an alloy substrate, as well as an interface inter-miscible layer and a CrNx layer that were attached to a surface of the alloy substrate in sequence, wherein the alloy substrate was the low-alloy low-medium-carbon alloy steel 40CrNiMo, and thicknesses of the interface inter-miscible layer and the CrNx layer are shown in Table 2.

[0079] Example 4

[0080] This example was performed according to procedures as described in Example 1, except that: in step (2), the plasma nitridation was conducted at a nitridation temperature of 470 °C and a nitridation voltage of 700 V.

[0081] The high-wear-resistant alloy component prepared by the above method was composed of an alloy substrate, as well as an interface inter-miscible layer and a CrNx layer that were attached to a surface of the alloy substrate in sequence, wherein the alloy substrate was the low-alloy low-medium-carbon alloy steel 40CrNiMo, and thicknesses of the interface inter-miscible layer and the CrNx layer are shown in Table 2.

[0082] Example 5

[0083] This example was performed according to procedures as described in Example 1, except that: in step (1), during the magnetron sputtering chromium plating, a negative bias voltage of -100 V was applied and maintained throughout the sputtering; and in step (2), the plasma nitridation was conducted at a nitridation voltage of 580 V, wherein the nitridation atmosphere was a mixture of NH3 and Ar, a flow ratio of NH3 to Ar was set to 5:1, and a flow rate of NH3 was 0.5 L / min.

[0084] The high-wear-resistant alloy component prepared by the above method was composed of an alloy substrate, as well as an interface inter-miscible layer and a CrNx layer that were attached to a surface of the alloy substrate in sequence, wherein the alloy substrate was the low-alloy low-medium-carbon alloy steel 40CrNiMo, and thicknesses of the interface inter-miscible layer and the CrNx layer are shown in Table 2.

[0085] Example 6

[0086] This example was performed according to procedures as described in Example 1, except that: after the plasma nitridation in step (2), grease coating was conducted, wherein a grease used was composed of solid grease, perfluoropolyethers (PFPE), a thickener, and polytetrafluoroethylene (PTFE), and a mass fraction of the PFPE was 70%.

[0087] The high-wear-resistant alloy component prepared by the above method was composed of an alloy substrate, as well as an interface inter-miscible layer, a CrNx layer, and a grease layer that were attached to a surface of the alloy substrate in sequence, wherein the alloy substrate was the low-alloy low-medium-carbon alloy steel 40CrNiMo, and thicknesses of the interface inter-miscible layer and the CrNx layer are shown in Table 2.

[0088] Example?

[0089] This example was performed according to procedures as described in Example 1, except that: in step (1), during the magnetron sputtering chromium plating, a negative bias voltage of -100 V was applied and maintained throughout the sputtering; and in step (2), the plasma nitridation was conducted for 7 h.

[0090] The high-wear-resistant alloy component prepared by the above method was composed of an alloy substrate, as well as an interface inter-miscible layer and a CrNx layer that were attached to a surface of the alloy substrate in sequence, wherein the alloy substrate was the low-alloy low-medium-carbon alloy 40CrNiMo, and thicknesses of the interface inter-miscible layer and the CrNx layer are shown in Table 2.

[0091] Examples

[0092] This example was performed according to procedures as described in Example 1, except that: in step (1), during the magnetron sputtering chromium plating, a negative bias voltage of -100 V was applied and maintained throughout the sputtering; in step (2), the plasma nitridation was conducted for 7 h; and after the plasma nitridation, grease coating was conducted, wherein a grease was composed of solid grease, PFPE, thickener, and PTFE, and a mass fraction of the PFPE was 70%. While remaining steps were the same as those in Example 1.

[0093] The high-wear-resistant alloy component prepared by the above method was composed of an alloy substrate, as well as an interface inter-miscible layer, a CrNx layer, and a grease layer that were attached to a surface of the alloy substrate in sequence, wherein the alloy substrate was the low-alloy low-medium-carbon alloy steel 40CrNiMo, and thicknesses of the interface inter-miscible layer and the CrNx layer are shown in Table 2.

[0094] Example 9

[0095] This example was performed according to procedures as described in Example 1, except that: in step (1), during the magnetron sputtering chromium plating, a negative bias voltage of -100 V was applied and maintained throughout the sputtering; in step (2), the plasma nitridation was conducted for 10 h; and after the plasma nitridation, grease coating was conducted, wherein a grease used was composed of solid grease, PFPE, a thickener, and PTFE, and a mass fraction of the PFPE was 70%.

[0096] The high-wear-resistant alloy component prepared by the above method was composed of an alloy substrate, as well as an interface inter-miscible layer, a CrNx layer, and a grease layer that were attached to a surface of the alloy substrate in sequence, wherein the alloy substrate was the low-alloy low-medium-carbon alloy steel 40CrNiMo, and thicknesses of the interface inter-miscible layer and the CrNx layer are shown in Table 2.

[0097] Example 10

[0098] This example was performed according to procedures as described in Example 1, except that: in step (1), the alloy substrate was specifically a transmission shaft component, which was made of still low-alloy low-medium-carbon alloy steel 40CrNiMo (surface modification was performed only on a spline tooth part of the transmission shaft, a transmission shaft part thereof was masked by a sleeve method, and therefore only the spline tooth part was subjected to magnetron sputtering cleaning, magnetron sputtering chromium plating, and plasma nitridation); in step (1), during the magnetron sputtering chromium plating, a negative bias voltage of -100 V was applied and maintained throughout the sputtering; in step (2), the plasma nitridation was conducted at a nitridation voltage of 580 V, wherein the nitridation atmosphere was a mixture of NEb and Ar, a flow ratio of NH3 to Ar was set to 5:1, and a flow rate of NH3 was 0.5 L / min.

[0099] The high-wear-resistant transmission shaft component prepared by the above method was composed of a transmission shaft substrate, as well as an interface inter-miscible layer and a CrNx layer that were attached to a surface of the transmission shaft substrate in sequence, wherein the transmission shaft substrate was the low-alloy low-medium-carbon alloy steel 40CrNiMo, and thicknesses of the interface inter-miscible layer and the CrNx layer are shown in Table 2.

[0100] Comparative Example 1

[0101] In this comparative example, provided was the alloy to be treated in step (1) of Example 1, i.e., the low-alloy low-medium-carbon alloy steel 40CrNiMo.

[0102] Table 1 Specific process parameters of shot peening treatment with high-pressure waterjet and surface modification parameters of obtained products in Examples 1 to 10 Process parameters Abrasives in waterjet Steel shot Jet pressure (MPa) 50 Nozzle feed speed (mm / min) 6 Jet-to-target distance (mm) 10 Jet angle 90° Surface modification parameters Surface roughness Ra (pm) 1.32-1.50 Surface residual stress (MPa) -691 Surface modification layer depth (pm) 100-120 Grain size within 0-30 pm surface modification layer (nm) 20-70

[0103] Table 2 Thickness of each wear-resistant layer on surfaces of the high-wear-resistant alloys prepared in Examples 1 to 10 Thickness of interface inter-miscible layer / pm Thickness of CrNx layer / pm Thickness of silver layer / pm Example 1 0.7 2.0-2.5 — Example 2 0.7 2.0-2.5 2.5-3.0 Example 3 0.7 4.0-5.0 — Example 4 0.6 2.0-2.5 — Example 5 0.7 2.5-3.0 — Example 6 0.7 2.0-2.5 — Example 7 0.6 2.5-3.0 — Example 8 0.6 4.0-5.0 — Example 9 0.7 4.0-5.0 — Example 10 0.7 2.5-3 —

[0104] Performance test

[0105] Test Example 1

[0106] The high-wear-resistant alloy samples prepared in Examples 1 to 5 and the low-alloy low-medium-carbon alloy steel 40CrNiMo of Comparative Example 1 were separately assembled with a WC ball (with a hardness of Hv2000) into to friction pairs, which were used in fretting wear tests later. The parameters of the fretting wear tests were as follows: a load of 50 N, a frequency of 30 Hz, a displacement amplitude of 100 pm, and a time of 2 h. The results of fretting wear tests are shown in Table 3.

[0107] Table 3 Results of fretting wear tests using friction pairs composed of samples in Examples 1 to 5 and Comparative Example 1 as well as WC ball Sample state Wear depth of sample (pm) Comparative Example 1 40CrNiMo 15.66 Example 1 6 h chrome plating-490 °C / 10 h nitriding 40CrNiMo 2.97 Example 2 6 h chrome plating-490 °C / 10 h nitri di ng-Ag plating 40CrNiMo 2.93 Example 3 -100 V negative bias-assisted magnetron sputtering+7 h chromium plating+490 °C / 10 h nitriding 40CrNiMo 2.00 Example 4 6 h chrome plating+470 °C / 700V / 10 h nitriding 40CrNiMo 3.67 Example 5 -100 V negative bias-assisted magnetron sputtering+6 h chromium plating+490 °C / 580 V / 10 h nitriding (NH3: Ar=5:l) 40CrNiMo 2.60

[0108] As shown in Table 3, the 40CrNiMo sample of the Comparative Example 1 without any surface treatment has a wear depth of as high as 15.66 pm, while the high-wear-resistant alloy samples obtained by the method in Examples 1 to 5 have a wear depth of only 2.00-3.67 pm. These results show that the high-wear-resistant coating prepared by the method shows high wear resistance.

[0109] Test Example 2

[0110] The high-wear-resistant alloy samples prepared in Examples 1 and 2 and the low-alloy low-medium-carbon alloy steel 40CrNiMo of Comparative Example 1 were separately assembled with a WC ball (with a hardness of Hv2000) into friction pairs, which were used in fretting wear tests. Parameters of the fretting wear tests were as follows: there were 5 wear stages with a total wear time of 12 h (wear parameters shown in Table 4). Results of the fretting wear tests are shown in Table 5.

[0111] Table 4 Parameters of 12 h fretting wear test Load(N) Frequency (Hz) Displacement amplitude (pm) Time (h) First stage 10 190 10 2 Second stage 30 100 40 2 Third stage 50 30 100 4 Fourth stage 30 100 40 2 Fifth stage 10 190 10 2 Total wear time / h — 12

[0112] Table 5 Results of fretting wear tests using friction pairs composed of samples in Examples 1 and 2 and Comparative Example 1 as well as WC ball Sample state Wear depth of sample (pm) Comparative Example 1 40CrNiMo 23.475 Example 1 6 h chrome plating+490 °C / 10 h nitriding 40CrNiMo 6.14 Example 2 6 h chrome plating+490 °C / 10 h nitriding+Ag plating 40CrNiMo 4.58

[0113] As shown in Table 5, the 40CrNiMo sample of the Comparative Example 1 without any surface treatment has a wear depth of as high as 23.475 pm, while the high-wear-resistant coating samples obtained by the method in Examples 1 and 2 have a wear depth of only 4.58-6.14 pm. These results show that the high-wear-resistant coating prepared by the method shows desirable wear resistance.

[0114] Test Example 3

[0115] The high-wear-resistant alloy samples prepared in Examples 1 to 2 and 6 to 9 and the low-alloy low-medium-carbon alloy steel 40CrNiMo of Comparative Example 1 were separately assembled with a 20Cr3MoWVA steel ball (with a hardness of Hv400) into friction pairs, which were used in fretting wear tests. Parameters of the fretting wear tests were as follows: there were 5 wear stages with a total wear time of 12 h (wear parameters shown in Table 4). Results of the fretting wear tests are shown in Table 6.

[0116] Table 6 Results of 12 h fretting wear tests using friction pairs composed of samples in Examples 1 to 2 and 6 to 9 and Comparative Example 1 as well as 20Cr3MoWVA ball Sample state Wear depth of sample (pm) Wear volume of steel ball (mm3) Comparative Example 1 40CrNiMo 17.2 0.081 Example 1 6 h chrome plating+490 °C / 10 h nitriding 40CrNiMo 0 0.0559 Example 2 6 h chrome plating+490 °C / 10 h nitriding+Ag plating 40CrNiMo 1.94 0.1179 Example 6 6 h chrome plating+490 °C / 10 h nitri di ng+grease layer 40CrNiMo 0 0.0088 Example 7 -100 V negative bias-assisted magnetron sputtering+6 h chromium plating+490 °C / 7 h nitriding 40CrNiMo 0 0.0501 Example 8 -100 V negative bias-assisted magnetron sputtering+6 h chromium plating+490 °C / 7 h nitriding+grease layer 40CrNiMo 4.0 0.000251 Example 9 -100 V negative bias-assisted magnetron sputtering+7 h chromium plating+490 °C / 10 h nitriding+grease layer 40CrNiMo 1.9 0.0034 Average wear loss Sample average wear depth 1.3 pm Steel ball average wear volume 0.039 mm3

[0117] As shown in Table 6, the 40CrNiMo in Comparative Example 1 without any surface treatment has a wear depth of as high as 17.2 pm, and the steel ball has a wear volume of 0.081 mm3; while the high-wear-resistant alloy samples obtained by the methods in Examples 1 to 2 and 6 to 9 have a wear depth of only 0-4.0 pm and the steel ball has a wear volume of 0-0.1179 pm. These results show that the surface coating of high-wear-resistant alloy component prepared by the method shows desirable wear resistance.

[0118] The microscopic appearance of the surface coating structure of the high-wear-resistant alloy component sample prepared in Example 1 was observed by SEM. The SEM image is shown in FIG.

[0119] As shown in FIG. 1, the surface coating of the high-wear-resistant alloy component sample has a uniform and dense structure, fine grains, and a particle size of 50-100 nm, showing higher surface hardness and strength and thus having better wear resistance.

[0120] The high-wear-resistant alloy component sample prepared in Example 1 was cut longitudinally, and the microscopic appearance of the longitudinal structure of the surface coating was observed by SEM (in order to avoid damaging the coating during cutting, conventional nickel plating was pre-performed on the coating surface for protection; the SEM image shows the cut nickel-plated layer). Further, the element distribution of the longitudinal structure of the surface coating was determined by an EDS spectrometer. The resulting SEM image is shown in FIG. 2, and the energy spectra of the element distribution are shown in FIG. 3 A to FIG. 3C, in which, FIG. 3 A shows an energy spectrum of the element distribution of the whole coating, FIG. 3B shows an energy spectrum of the element distribution in a CrNx layer region of FIG. 3 A, and FIG. 3C shows an energy spectrum of the element distribution of an interface inter-miscible layer region of FIG. 3A.

[0121] As shown in FIG. 2, the upper dark gray part represents the CrNx layer, and the lower light-colored part represents the interface inter-miscible layer; an interface between the two parts of the coating is tightly bonded, and there is no obvious boundary between the interface inter-miscible layer and the substrate, indicating that a strong metallurgical bond is achieved between the coating and the substrate. In addition, the overall structure of the coating is uniform and dense, with fine grains, showing high strength and hardness, such that the high-wear-resistant coating sample achieves excellent wear resistance.

[0122] As shown in FIG. 3A to FIG. 3C, there is an atomic diffusion gradient interface between the CrNx layer and the substrate, and the Cr and Fe atoms are interlaced, indicating that a strong metallurgical bond is achieved between the coating and the substrate; the thickness of the CrNx layer is 2.5 pm (NOTE: since N in CrNx is a light element, it could not be clearly displayed in EDS detection, and only Cr could be displayed, only the Cr element could be clearly seen in the CrNx layer in FIG. 3B, and Cr element region actually represents the CrNx part), and the coating is relatively uniform in thickness.

[0123] The microscopic appearance of the surface coating structure of the high-wear-resistant alloy component sample prepared in Example 3 was observed by SEM. The SEM image is shown in FIG. 4.

[0124] As shown in FIG. 4, the surface coating of the high-wear-resistant alloy component sample has a uniform and dense structure, grains in a molten state, tightly packed particles, and fuzzy interface among particles, with a particle size larger than that of Example 1, i.e., about 1 pm. However, the coating could still show higher surface hardness and strength, thereby having better wear resistance.

[0125] The high-wear-resistant alloy component sample prepared in Example 3 was cut longitudinally, and the microscopic appearance of the longitudinal structure of the surface coating was observed by SEM (in order to avoid damaging the coating during cutting, conventional nickel plating was pre-performed on the coating surface for protection; the SEM image shows the cut nickel-plated layer part). Further, the element distribution of the longitudinal structure of the surface coating was determined by an EDS spectrometer. The resulting SEM image is shown in FIG. 5, and the energy spectra of the element distribution are shown in FIG. 6Ato FIG. 6C, in which, FIG. 6A shows an energy spectrum of the element distribution of the whole coating, FIG. 6B shows an energy spectrum of the element distribution of a CrNx layer region of FIG. 6A, and FIG. 6C shows an energy spectrum of the element distribution of an interface inter-miscible layer region of FIG. 6A.

[0126] As shown in FIG. 5, the upper dark gray part represents the CrNx layer, and the lower light-colored part represents the interface inter-miscible layer; an interface between the two parts of the coating is tightly bonded, and there is no obvious boundary between the interface inter-miscible layer and the substrate, indicating that a strong metallurgical bond is achieved between the coating and the substrate, such that the high-wear-resistant coating sample achieves excellent wear resistance.

[0127] As shown in FIG. 6A to FIG. 6C, there is an atomic diffusion gradient interface between the CrNx layer and the substrate, and the Cr and Fe atoms are interlaced, indicating that a strong metallurgical bond is achieved between the coating and the substrate; the thickness of the CrNx layer is 5 urn (NOTE: since N in CrNx is a light element, it could not be clearly displayed in EDS detection, and only Cr could be displayed, such that only the Cr element could be clearly seen in the CrNx layer in FIG. 6B, and Cr element region actually represents the CrNx layer part), and the coating is relatively uniform in thickness.

[0128] The miscibility of Cr element and substrate element in the interface inter-miscible layer of Example 1 was observed by scanning electron microscope-energy dispersive spectrometer (SEM-EDS) in line scanning mode. The observed element interaction diagram is shown in FIG. 7A to FIG. 7C.

[0129] As shown in FIG. 7Ato FIG. 7C, Cr and Fe atoms are interlaced with each other, and there is a transitional composition gradient therebetween. The atomic interaction thickness is 0.5 pm, and the atoms at the interface diffuse with each other, indicating that a strong metallurgical bond is achieved between the coating and the substrate.

[0130] A bonding strength between the surface coating and the substrate of the high-wear-resistant alloy component in Example 1 was measured using a micron scratch tester. The scratch morphology obtained by the measurement is shown in FIG. 8.

[0131] As shown in FIG. 8, observed from the scratch morphology of the surface coating of the high-wear-resistant alloy component, the coating does not crack or peel off, indicating that a strong bond is achieved between the coating and the substrate.

[0132] The three scratches formed on the sample of Example 1 as shown in FIG. 8 were measured by the micron scratch instrument, and a diagram was plotted by using Origin according to the bonding force data between the surface coating and the substrate. An obtained relationship diagram between the actual load and the friction force is shown in FIG. 9 (in which Tests 1 to 3 correspond to the three scratches in FIG. 8, respectively).

[0133] As shown in FIG. 9, the actual load when a friction force changing trend changes significantly is 130 N, indicating that the bonding force between the coating and the substrate is 130 N, and that a strong metallurgical bonding is achieved between the coating and the substrate.

[0134] In summary, the wear-resistant coating on the surface of the high-wear-resistant alloy component sample obtained by the method according to the present disclosure has a high bonding strength with the alloy substrate. Moreover, the high-wear-resistant coating component shows excellent wear resistance and has a longer service life under fretting wear conditions.

[0135] The above descriptions are merely preferred embodiments of the present disclosure. It should be noted that a person of ordinary skill in the art may further make several improvements and modifications without departing from the principle of the present disclosure, but such improvements and modifications should be deemed as falling within the protection scope of the present disclosure.

Claims

1. A method for preparing a coating on an alloy substrate, comprising the steps of(1) subjecting a surface of the alloy substrate to shot peening treatment with high-pressure water jet, sand blasting treatment, and surface corrosion treatment in sequence, to obtain a surface-pretreated alloy component; and(2) subjecting the surface-pretreated alloy component obtained in step (1) to magnetron sputtering chromium plating and plasma nitridation in sequence, to obtain the coating on the alloy substrate.

2. The method as claimed in claim 1, wherein the shot peening treatment with high-pressure waterjet in step (1) is conducted with parameters comprising: an abrasive used in a waterjet being a steel shot; a jet pressure of 20 MPa to 120 MPa; a nozzle feed speed of 5 mm / min to 20 mm / min; a jet-to-target distance of 5 mm to 15 mm; and a jet angle of 85° to 95°.

3. The method as claimed in claim 1 or 2, wherein a product obtained from the shot peening treatment with high-pressure waterjet in step (1) has surface modification parameters comprising: a surface roughness Ra of 0.8 pm to 2.5 pm; a surface residual stress of -600 MPa to -1,000 MPa; a surface modification layer depth of 60 pm to 120 pm; and a grain size of 20 nm to 100 nm within a modification layer depth of 0 pm to 30 pm.

4. The method as claimed in claim 1, wherein a product obtained from the sand blasting treatment in step (1) has a surface roughness Ra of 0.8 pm to 2.5 pm.

5. The method as claimed in claim 1, wherein the surface corrosion treatment in step (1) is conducted with a solution of nitric acid in alcohol for 10 s to 120 s.

6. The method as claimed in claim 1, wherein the alloy substrate in step (1) is selected from the group consisting of a low-alloy low-medium-carbon alloy steel and a stainless steel.

7. The method as claimed in claim 1, wherein the magnetron sputtering chromium plating in step (2) is conducted with parameters comprising: a target-to-substrate distance of 8 cm to 12 cm; a vacuum degree of 5 / HT4 Pa to 5><10’3 Pa; and a chromium plating power of 80 W to 150 W; achromium plating temperature of 100 °C to 400 °C; and a chromium plating time of 4 h to 8 h.

8. The method as claimed in claim 1, wherein the plasma nitridation in step (2) is conducted with parameters comprising: a nitridation atmosphere being NH3, or a mixture of NH3 and argon; a nitridation temperature of 450 °C to 520 °C; a nitridation voltage of 580 V to 720 V; a nitridation pressure of 200 Pa to 450 Pa; and a nitridation time of 7 h to 12 h.

9. A coating obtained by the method as claimed in any one of claims 1 to 8, comprisingan interface inter-miscible layer and a CrNx layer, which are attached to a surface of the alloy substrate in sequence.

10. The coating as claimed in claim 9, wherein the interface inter-miscible layer has a thickness of 0.5 pm to 2 pm, and the CrNx layer has a thickness of 2 pm to 5 pm.

11. An alloy component, comprisingan alloy substrate; andthe coating as claimed in claim 9 or 10 that is attached onto a surface of the alloy substrate.

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