WC-Co hard alloy sealing ring with diamond coating deposited on surface and preparation method of WC-Co hard alloy sealing ring

Abstract

The invention discloses a WC-Co hard alloy sealing ring with a diamond coating deposited on the surface and a preparation method of the WC-Co hard alloy sealing ring, and belongs to the technical field of mechanical surface treatment.The method comprises the steps that (1) a cleaned and dried WC-Co hard alloy substrate is subjected to acid treatment so that a Co-removed loose layer can be formed on the surface of the WC-Co hard alloy substrate; (2) magnetron sputtering is carried out on the substrate treated in the step (1), so that a Si layer is deposited on the surface of the Co-removed loose layer to serve as an intermediate transition layer, and annealing treatment is carried out on the intermediate transition layer; and (3) the substrate treated in the step (2) is placed in turbid liquid containing nano diamond powder for ultrasonic oscillation and crystal planting, the substrate is taken out and dried, then a diamond film is prepared through hot filament chemical vapor deposition, and the WC-Co hard alloy sealing ring with the diamond coating deposited on the surface is obtained. The method is simple, controllable, good in repeatability and easy to implement, and the problem of film-base matching between the hard alloy and the diamond can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical surface treatment, and particularly relates to a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface and a preparation method thereof. Background Art

[0002] Cemented carbide sealing rings are powder metallurgy sealing rings made primarily of micron-sized powders of high-hardness refractory metal carbides (such as WC and TiC), with cobalt (Co), nickel (Ni), or molybdenum (Mo) as a binder. These rings are pressed into a ring-shaped form and sintered in a vacuum furnace or hydrogen reduction furnace. Cemented carbide mechanical sealing rings offer a range of excellent properties, including high hardness, wear resistance, strength, toughness, heat resistance, and corrosion resistance. Their high hardness and wear resistance remain essentially unchanged even at temperatures of 500°C, and they maintain a high hardness at 1000°C.

[0003] As operating conditions become increasingly demanding, the use of surface protective coating technology to enhance the service reliability of carbide sealing rings in extreme environments can effectively enhance their overall performance, allowing them to better adapt to complex operating conditions. Diamond coatings combine excellent frictional self-lubrication, high thermal conductivity, and corrosion resistance, making them an ideal end-face protection material. For example, Chinese patent document CN113770536A discloses a dynamic sealing ring provided with a surface-textured diamond coating and a preparation method thereof. In this invention, a diamond coating is deposited on the surface of the dynamic sealing ring substrate by hot-wire chemical vapor deposition, and then the diamond coating is polished using a femtosecond laser. The polished surface of the dynamic sealing ring substrate is then subjected to laser surface texturing to obtain a dynamic sealing ring provided with a surface-textured diamond coating. This dynamic sealing ring can be used in complex and changeable service environments. Although this invention involves the introduction of a diamond coating on the surface of the dynamic sealing ring, it cannot solve the problem of mismatch in the intrinsic interface properties between cemented carbide and diamond (such as thermal expansion coefficient mismatch, weak bonding force, etc.). Coating peeling may occur under extreme loads or long-term service.

[0004] The mismatch in intrinsic interface properties between cemented carbide and diamond is mainly manifested in the following: the thermal expansion coefficients between cemented carbide and diamond are quite different. At the same time, the bonding phase Co in cemented carbide, such as WC-Co matrix, will diffuse to the surface under the action of high temperature. The diffused Co interacts with active carbon ions on the WC-Co surface and dissolves a large amount of carbon, resulting in the delayed nucleation process of CVD (chemical vapor deposition) diamond on the WC-Co surface. At the same time, Co and C have a complex interaction relationship, which has an extremely adverse effect on the adhesion between the diamond coating and WC-Co.

[0005] Chinese patent publication CN107034467A discloses a diamond-coated cemented carbide component and its preparation method. The method comprises: preparing a cemented carbide substrate, cleaning and pre-treating it, then placing it in a diamond powder suspension for implantation of diamond seeds; depositing an initial tungsten layer on the surface of the implanted diamond seeds, so that the initial tungsten layer partially covers the implanted diamond seeds; annealing the tungsten-coated substrate in a reducing atmosphere; and finally, depositing a diamond coating on the annealed tungsten layer to obtain a diamond-coated cemented carbide component. However, this invention may still have the problem of Co diffusion affecting the film-substrate bonding.

[0006] Therefore, it is necessary to develop a new method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface. Summary of the Invention

[0007] In order to address the deficiencies in the above-mentioned prior art, the present invention provides a method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface. The method is simple and controllable, has good repeatability, is easy to implement, and can solve the film-base matching problem between cemented carbide and diamond.

[0008] The specific technical solutions adopted are as follows: A method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface comprises the following steps: (1) The WC-Co cemented carbide substrate is cleaned and dried for pretreatment, and then the cleaned and dried WC-Co cemented carbide substrate is acid-treated to form a Co-removed loose layer on the surface of the WC-Co cemented carbide substrate; (2) performing magnetron sputtering on the substrate treated in step (1) to deposit a Si layer as an intermediate transition layer on the surface of the Co-removed loose layer, and performing annealing on the intermediate transition layer; (3) placing the substrate treated in step (2) in a suspension containing nano-diamond powder and ultrasonically vibrating the substrate to plant the crystals, taking it out and drying it, and then using hot wire chemical vapor deposition to prepare a diamond film to obtain the WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface; In the WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface, the thickness of the diamond film is 8 to 20 μm, the thickness of the intermediate transition layer is 500 nm to 5 μm, and more preferably, the thickness of the intermediate transition layer is 1 μm to 2 μm.

[0009] The present invention first uses a one-step pickling process to form a certain thickness of Co-free loose layer on the surface of a WC-Co cemented carbide substrate. Then, a magnetron sputtering method is used to deposit an intermediate transition layer with a thermal expansion coefficient similar to that of diamond. The intermediate transition layer is then heat-treated and annealed. Finally, hot-wire chemical vapor deposition is used to design and prepare diamond coatings of different crystal forms. The pickling process can effectively remove the binding phase Co in the WC-Co cemented carbide substrate, reducing its influence on diamond nucleation and growth. Magnetron sputtering can effectively prevent the influence of the binding phase Co on CVD diamond deposition. High-temperature magnetron sputtering at around 300°C can form C-Si bonds to improve the compactness between layers and increase the interlayer density. The use of Si with a thermal expansion coefficient similar to that of diamond can improve the film-substrate matching between the WC-Co cemented carbide and diamond. The annealing heat treatment can reduce the interfacial residual stress caused by the magnetron sputtering process. At the same time, CW and C-Si bonds are formed between the cemented carbide and the intermediate transition layer to improve the film-substrate bonding strength.

[0010] Specifically, the pretreatment method includes: ultrasonically cleaning the WC-Co cemented carbide substrate using acetone, ethanol and deionized water in sequence to remove dust and impurities on the surface thereof, and then drying it with nitrogen gas.

[0011] Preferably, the acid treatment is performed using a mixed acid solution prepared by equal volume ratios of a hydrochloric acid solution with a volume concentration of 30 to 40 vt.%, a nitric acid solution with a volume concentration of 60 to 70 vt.%, and water, and the acid treatment time is 10 to 20 min.

[0012] Under the above acid treatment parameters, it is helpful to prepare a Co-removed loose layer with an appropriate thickness (50-100 μm) and cause little mechanical damage to the WC-Co cemented carbide substrate.

[0013] Furthermore, after the acid treatment, the acid-treated WC-Co cemented carbide substrate is ultrasonically cleaned using deionized water and ethanol until the pH value of the washing solution reaches neutral.

[0014] Preferably, during magnetron sputtering, Si target material is used, and the parameters of magnetron sputtering include: vacuum degree <1×10 -4 Pa, power 100~120 W, gas pressure 0.8~1.2 Pa, argon flow rate of 20 sccm~35 sccm, sputtering temperature maintained at 250~350℃, and sputtering time 0.8~2 h.

[0015] Magnetron sputtering has the characteristics of strong film bonding, dense and uniform structure, and low deposition temperature. By regulating the sputtering power, vacuum degree and gas ratio, the film composition and thickness can be precisely controlled. Compared with the Si layer prepared by the sol-gel-reduction method, it has fewer impurity elements, higher purity, higher density, lower porosity, excellent Si crystal quality, better uniformity, and higher surface flatness. It can effectively cover and passivate the surface of the Co-free loose layer, and improve the interfacial bonding between the subsequently deposited diamond layers without affecting the diamond growth rate and the surface morphology of the diamond film.

[0016] Preferably, the annealing temperature is 650-850° C., and the annealing time is 3-8 h.

[0017] By annealing the intermediate transition layer, the interface residual stress can be reduced, and CW and C-Si bonds can be formed between the WC-Co cemented carbide substrate and the intermediate transition layer, further improving the film-base bonding strength.

[0018] Preferably, in step (3), the concentration of the nano-diamond powder in the suspension containing the nano-diamond powder is 0.1 to 5 wt %, and the ultrasonic oscillation time is 0.1 to 1.5 h.

[0019] Preferably, tantalum wire is used when preparing diamond film by hot wire chemical vapor deposition, and the process parameters are: methane flow rate of 6 to 10 mL / min, hydrogen flow rate of 200 to 400 mL / min, nitrogen flow rate of 0 to 4 mL / min, deposition pressure of 2.0 to 2.5 KPa, deposition power of 3600 to 4000 W, wire pitch of 6 to 8 mm, and deposition time of 2 to 4 h.

[0020] The prepared diamond film is a micron-crystalline diamond MCD film, a submicron-crystalline diamond SMCD film, a nano-crystalline diamond NCD film or an ultra-nano-crystalline diamond UNCD film.

[0021] Preferably, the deposited diamond film is a micron-crystalline diamond (MCD) film, which has been experimentally shown to have an adhesion force of 62.55 N and an optimal film-substrate bonding force.

[0022] The present invention also provides a WC-Co hard alloy sealing ring with a diamond coating deposited on the surface, which is prepared by adopting the preparation method of the WC-Co hard alloy sealing ring with a diamond coating deposited on the surface.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation method of the WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface provided by the present invention has simple steps, is easy to operate, and has good repeatability.

[0024] (2) The one-step pickling treatment can effectively remove the bonding phase Co in the WC-Co matrix, and the mechanical damage to the WC-Co cemented carbide substrate is small.

[0025] (3) Setting an intermediate transition layer can effectively prevent the influence of the bonding phase Co on diamond deposition. The intermediate transition layer prepared by high-temperature magnetron sputtering at 300°C forms C-Si bonds, which can improve the density between layers. Annealing heat treatment can reduce the interfacial residual stress caused by the magnetron sputtering process. At the same time, high-temperature heat treatment annealing can form CW and C-Si bonds between the substrate and the intermediate transition layer to improve the film-substrate bonding strength.

[0026] (4) After the introduction of the Si intermediate transition layer, the adhesion strength of the diamond coating increased by about 30%, reaching a maximum of 62.55 N, and the film-substrate bonding strength was good. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The WC-Co cemented carbide substrate before and after acid treatment in Example 1, wherein (a) is before acid treatment and (b) is after acid treatment.

[0028] Figure 2 1 is the characterization result of the Co-removed loose layer formed in Example 1, wherein A and B represent boundaries.

[0029] Figure 3 This is a cross-sectional TEM image of a WC-Co cemented carbide substrate with a diamond coating deposited on its surface prepared in Example 1. DETAILED DESCRIPTION

[0030] In order to make the objects, features and advantages of the present invention more clearly understood, a detailed description is given below using specific embodiments. In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in the various embodiments of the present invention can be combined accordingly without conflicting with each other.

[0031] Example 1 (1) Take the WC-Co carbide dynamic seal ring substrate and ultrasonically clean the WC-Co carbide substrate with acetone, ethanol and deionized water in turn to remove dust and impurities on its surface. After cleaning, blow it dry with nitrogen and use a mixed acid solution (38vt.%HCl+ 68vt.%HNO3+H2O =1:1:1) for acid treatment. The acid treatment time is 13 min. After the acid treatment, ultrasonic cleaning is performed in deionized water for 3 times and then in ethanol for 2 times. After the pH value of the washing solution reaches neutral, take it out and dry it.

[0032] (2) Magnetron sputtering is performed on the substrate treated in step (1) to deposit a Si layer on the surface of the Co-removed loose layer. During magnetron sputtering, a Si target is used. The parameters of magnetron sputtering include: vacuum degree <1×10 -4 Pa, power 120 W, gas pressure 1.0 Pa, argon flow rate of 25 sccm, sputtering temperature maintained at 350 ℃, sputtering time 1 h, and further annealing treatment of the Si layer. During the annealing treatment, the heating rate was 50 ℃ / min, and it was raised from room temperature to 750 ℃ ​​and then maintained for 4 h before natural cooling.

[0033] (3) The substrate treated in step (2) was placed in an ethanol suspension containing 5 wt% nano-diamond powder and ultrasonically vibrated to plant crystals for 0.5 h. After being taken out and dried, a diamond film was prepared by hot-wire chemical vapor deposition. The hot-wire used was a tantalum wire. During deposition, the methane flow rate was 8 mL / min, the hydrogen flow rate was 400 mL / min, the nitrogen flow rate was 0 mL / min, the deposition pressure was 2.2 KPa, the deposition power was 4000 W, the wire pitch was 8 mm, and the deposition time was 4 h. A WC-Co cemented carbide sealing ring with a surface-deposited micron-crystalline diamond MCD coating was prepared.

[0034] In the WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface, the thickness of the diamond film is about 4.8 μm, and the thickness of the intermediate transition layer is about 1.2 μm.

[0035] Comparative Example 1 The only difference between the present invention and Example 1 is that the intermediate transition layer Si layer is not deposited, and the other processes and parameters are the same.

[0036] Example 2 (1) Take the WC-Co carbide dynamic seal ring substrate and ultrasonically clean the WC-Co carbide substrate with acetone, ethanol and deionized water in turn to remove dust and impurities on its surface. After cleaning, blow it dry with nitrogen and use a mixed acid solution (38vt.%HCl+ 68vt.%HNO3+H2O =1:1:1) for acid treatment. The acid treatment time is 13 min. After the acid treatment, ultrasonic cleaning is performed in deionized water for 3 times and then in ethanol for 2 times. After the pH value of the washing solution reaches neutral, take it out and dry it.

[0037] (2) Magnetron sputtering is performed on the substrate treated in step (1) to deposit a Si layer on the surface of the Co-removed loose layer. During magnetron sputtering, a Si target is used. The parameters of magnetron sputtering include: vacuum degree <1×10 -4Pa, power 120 W, gas pressure 1.0 Pa, argon flow rate of 25 sccm, sputtering temperature maintained at 350 ℃, sputtering time 1 h, and further annealing treatment of the Si layer. During the annealing treatment, the heating rate was 50 ℃ / min, and it was raised from room temperature to 750 ℃ ​​and then maintained for 4 h before natural cooling.

[0038] (3) The substrate treated in step (2) was placed in an ethanol suspension containing 5 wt% nano-diamond powder and ultrasonically vibrated to plant crystals for 0.5 h. After being taken out and dried, a diamond film was prepared by hot wire chemical vapor deposition. The hot wire used was tantalum wire. During deposition, the methane flow rate was 8 mL / min, the hydrogen flow rate was 400 mL / min, the nitrogen flow rate was 0 mL / min, the deposition pressure was 2.2 KPa, the deposition power was 3600 W, the wire pitch was 8 mm, and the deposition time was 4 h. A WC-Co cemented carbide sealing ring with a surface-deposited submicron-crystalline diamond SMCD coating was prepared.

[0039] Comparative Example 2 The only difference between the present invention and Example 2 is that the intermediate transition layer Si layer is not deposited, and the other processes and parameters are the same.

[0040] Example 3 (1) Take the WC-Co carbide dynamic seal ring substrate and ultrasonically clean the WC-Co carbide substrate with acetone, ethanol and deionized water in turn to remove dust and impurities on its surface. After cleaning, blow it dry with nitrogen and use a mixed acid solution (38vt.%HCl+ 68vt.%HNO3+H2O =1:1:1) for acid treatment. The acid treatment time is 13 min. After the acid treatment, ultrasonic cleaning is performed in deionized water for 3 times and then in ethanol for 2 times. After the pH value of the washing solution reaches neutral, take it out and dry it.

[0041] (2) Magnetron sputtering is performed on the substrate treated in step (1) to deposit a Si layer on the surface of the Co-removed loose layer. During magnetron sputtering, a Si target is used. The parameters of magnetron sputtering include: vacuum degree <1×10 -4 Pa, power 120 W, gas pressure 1.0 Pa, argon flow rate of 25 sccm, sputtering temperature maintained at 350 ℃, sputtering time 1 h, and further annealing treatment of the Si layer. During the annealing treatment, the heating rate was 50 ℃ / min, and it was raised from room temperature to 750 ℃ ​​and then maintained for 4 h before natural cooling.

[0042] (3) The substrate treated in step (2) was placed in an ethanol suspension containing 5 wt% nano-diamond powder and ultrasonically vibrated to plant crystals for 0.5 h. After being taken out and dried, a diamond film was prepared by hot-wire chemical vapor deposition. The hot-wire used was a tantalum wire. During deposition, the methane flow rate was 8 mL / min, the hydrogen flow rate was 400 mL / min, the nitrogen flow rate was 0.8 mL / min, the deposition pressure was 2.0 KPa, the deposition power was 3600 W, the wire pitch was 8 mm, and the deposition time was 4 h. A WC-Co cemented carbide sealing ring with a nanocrystalline diamond NCD coating deposited on the surface was prepared.

[0043] Comparative Example 3 The only difference between the present invention and Example 3 is that the intermediate transition layer Si layer is not deposited, and the other processes and parameters are the same.

[0044] Example 4 (1) Take the WC-Co carbide dynamic seal ring substrate and ultrasonically clean the WC-Co carbide substrate with acetone, ethanol and deionized water in turn to remove dust and impurities on its surface. After cleaning, blow it dry with nitrogen and use a mixed acid solution (38vt.%HCl+ 68vt.%HNO3+H2O =1:1:1) for acid treatment. The acid treatment time is 13 min. After the acid treatment, ultrasonic cleaning is performed in deionized water for 3 times and then in ethanol for 2 times. After the pH value of the washing solution reaches neutral, take it out and dry it.

[0045] (2) Magnetron sputtering is performed on the substrate treated in step (1) to deposit a Si layer on the surface of the Co-removed loose layer. During magnetron sputtering, a Si target is used. The parameters of magnetron sputtering include: vacuum degree <1×10 -4 Pa, power 120 W, gas pressure 1.0 Pa, argon flow rate of 25 sccm, sputtering temperature maintained at 350 ℃, sputtering time 1 h, and further annealing treatment of the Si layer. During the annealing treatment, the heating rate was 50 ℃ / min, and it was raised from room temperature to 750 ℃ ​​and then maintained for 4 h before natural cooling.

[0046] (3) The substrate treated in step (2) was placed in an ethanol suspension containing 5 wt% nano-diamond powder and ultrasonically vibrated to plant crystals for 0.5 h. After being taken out and dried, a diamond film was prepared by hot wire chemical vapor deposition. The hot wire used was tantalum wire. During deposition, the methane flow rate was 8 mL / min, the hydrogen flow rate was 400 mL / min, the nitrogen flow rate was 4 mL / min, the deposition pressure was 2.0 KPa, the deposition power was 3600 W, the wire pitch was 8 mm, and the deposition time was 4 h. A WC-Co cemented carbide sealing ring with an ultra-nanocrystalline diamond UNCD coating deposited on the surface was prepared.

[0047] Comparative Example 4 The only difference between the present invention and Example 4 is that the intermediate transition layer Si layer is not deposited, and the other processes and parameters are the same.

[0048] Sample analysis Figure 1 The WC-Co cemented carbide substrate before and after acid treatment in Example 1, wherein (a) is before acid treatment, and (b) is after acid treatment. Figure 1 The results show that the surface after acid treatment has porous and concave morphology, which is completely different from the smooth and dense morphology of the surface before acid treatment.

[0049] Figure 2 These are the characterization results of the Co-free loose layer formed in Example 1, where A and B represent boundaries. The corresponding results indicate that 13 minutes of acid treatment can form an 83.7 μm Co-free loose layer on the substrate surface, and the average Co content in the 83.7 μm Co-free loose layer is significantly lower than 6%, especially at a depth of 30 μm from the substrate surface, where the Co content is almost 0.

[0050] Figure 3 This is a cross-sectional TEM image of a WC-Co cemented carbide substrate with a diamond coating deposited on its surface prepared in Example 1, wherein the Si intermediate transition layer exhibits high-density and continuous microstructural characteristics.

[0051] The samples prepared in Examples 1-4 and Comparative Examples 1-4 were further tested for interfacial adhesion. This testing was performed on a Revetest scratch testing system (CSM Revetest) using an HRC Rockwell indenter. The test parameters were: load 0-90 N, scratch length 5 mm, and sliding speed 1.5 mm / min. When placing the sample, ensure that it is perpendicular to the indenter; otherwise, this will affect the interaction between the diamond coating and the indenter, and thus the adhesion.

[0052] The test results show that the adhesion of the diamond coating in the samples prepared in Examples 1-4 is 62.55 N, 43.28 N, 27.32 N, and 23.06 N, respectively. The adhesion of the diamond coating in the samples prepared in Comparative Examples 1-4 is 47.63 N, SMCD 31.69 N, 20.54 N, and 18.44 N, respectively. After the introduction of the Si intermediate transition layer, the adhesion strength of the diamond coating is increased by about 30%, and the effect is significantly better.

[0053] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface, characterized in that: The following steps are involved: (1) The WC-Co cemented carbide substrate is cleaned and dried for pretreatment, and then the cleaned and dried WC-Co cemented carbide substrate is acid-treated to form a Co-removed loose layer on the surface of the WC-Co cemented carbide substrate; (2) performing magnetron sputtering on the substrate treated in step (1) to deposit a Si layer as an intermediate transition layer on the surface of the Co-removed loose layer, and performing annealing on the intermediate transition layer; (3) placing the substrate treated in step (2) in a suspension containing nano-diamond powder and ultrasonically vibrating the substrate to plant the crystals, taking it out and drying it, and then using hot wire chemical vapor deposition to prepare a diamond film to obtain the WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface; In a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface, the thickness of the diamond film is 8 to 20 μm, and the thickness of the intermediate transition layer is 500 nm to 5 μm.

2. The method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface according to claim 1, characterized in that: The pretreatment method includes: ultrasonically cleaning the WC-Co cemented carbide substrate using acetone, ethanol and deionized water in sequence, and drying it with nitrogen after cleaning.

3. The method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface according to claim 1, characterized in that: Acid treatment is performed using a mixed acid solution prepared in an equal volume ratio of a hydrochloric acid solution with a volume concentration of 30vt.% to 40vt.%, a nitric acid solution with a volume concentration of 60vt.% to 70vt.%, and water. The acid treatment time is 10 to 20 minutes.

4. The method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface according to claim 1, characterized in that: During magnetron sputtering, Si target material is used. The parameters of magnetron sputtering include: vacuum degree <1×10 -4 Pa, power 100~120 W, gas pressure 0.8~1.2 Pa, argon flow rate of 20 sccm~35 sccm, sputtering temperature maintained at 250~350 ℃, and sputtering time 0.8~2 h.

5. The method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface according to claim 1, characterized in that: The annealing temperature is 650-850°C, and the annealing time is 3-8 h.

6. The method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface according to claim 1, characterized in that: In step (3), the concentration of the nano-diamond powder in the suspension containing the nano-diamond powder is 0.1 to 5 wt%, and the ultrasonic oscillation time is 0.1 to 1.5 h.

7. The method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface according to claim 1, characterized in that: Tantalum wire is used to prepare diamond films by hot-wire chemical vapor deposition. The process parameters are: methane flow rate of 6-10 mL / min, hydrogen flow rate of 200-400 mL / min, nitrogen flow rate of 0-4 mL / min, deposition pressure of 2.0-2.5 kPa, deposition power of 3600-4000 W, wire pitch of 6-8 mm, and deposition time of 2-4 h.

8. The method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface according to claim 1, characterized in that: The prepared diamond film is a micron-crystalline diamond MCD film, a submicron-crystalline diamond SMCD film, a nano-crystalline diamond NCD film or an ultra-nano-crystalline diamond UNCD film.

9. The method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface according to claim 1, characterized in that: The deposited diamond film is a micron-crystalline diamond MCD film.

10. A WC-Co carbide sealing ring with a diamond coating deposited on its surface, characterized in that: The ring is prepared by the method for preparing a WC-Co cemented carbide sealing ring with a diamond coating deposited on the surface as described in any one of claims 1 to 9.

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