Diamond-like carbon coating for surface of ceramic matrix and preparation method of diamond-like carbon coating

Abstract

The invention provides a diamond-like coating for the surface of a ceramic matrix and a preparation method thereof, and belongs to the technical field of sealing materials, the preparation method specifically comprises the following steps: S1, adopting a linear ion beam technology, taking argon as working gas, and performing etching treatment on the surface of the ceramic matrix by utilizing ionized argon ions to obtain a zigzag microstructure; s2, a linear ion beam chemical vapor deposition method is adopted, acetylene / methane serves as working gas, the hydrocarbon precursor is ionized on the surface of the ceramic matrix subjected to etching treatment to form an interface mixing layer, and then the diamond-like coating is deposited to obtain the diamond-like coating used for the surface of the ceramic matrix. Compared with the prior art, the ion beam etching process is adopted to form the microstructure and the interface mixing layer on the surface, the influence of interface mismatching of the substrate and the DLC coating is reduced, the film-substrate binding force is improved, the supporting capacity of the surface DLC coating is improved, and high bearing is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sealing materials, and particularly relates to a diamond-like carbon coating for the surface of a ceramic matrix and a preparation method thereof. Background Art

[0002] Due to excellent mechanical properties, high-temperature and high-pressure stability, corrosion resistance, etc., silicon carbide / silicon nitride ceramic seals have broad application prospects in extreme working conditions such as deep-sea oil and gas, aerospace, and petrochemical industries. However, during the service of silicon carbide / silicon nitride seals under harsh working conditions, the wear resistance is still difficult to meet the requirements for long-term stable use, seriously affecting the normal operation of sealing equipment and increasing the operation cost.

[0003] Existing studies have shown that the use of diamond coatings can significantly improve the friction and wear performance of silicon carbide / silicon nitride. Since the rough surface of the diamond coating will increase the possibility of seal failure and leakage, complex polishing processes are generally required. Diamond-like carbon coatings (DLC) are amorphous carbon materials composed of a mixture of diamond-phase C-sp 3 bonds and graphite-phase C-sp 2 bonds, with excellent properties such as a smooth surface, friction reduction and wear resistance, and strong chemical inertness, which can effectively improve the service performance of silicon carbide / silicon nitride components. However, there are large differences in physical properties between DLC and silicon carbide / silicon nitride, and the intrinsically high stress of DLC leads to easy peeling and failure of the coating. In traditional solutions, the carbon precursor material can be directly pyrolyzed at high temperature to form DLC on the surface of the ceramic matrix, but there are problems such as poor stability, density, uniformity, and low hardness and insufficient wear resistance. In addition, by introducing metal transition layers such as Cr, W, Ti and doping with metal elements, the bonding strength between DLC and the silicon carbide / silicon nitride matrix can be improved. However, the introduction of metal elements leads to risks such as coating peeling and seal failure caused by metal corrosion when the coated silicon carbide / silicon nitride components are in typical corrosion working conditions such as the ocean and chemical industries. Summary of the Invention

[0004] The technical objective of the present invention is to address the challenges that the silicon carbide / silicon nitride sealing components have insufficient long-life service due to friction and wear under harsh working conditions, and the current DLC protective coating has poor bonding performance and the introduction of metal transition layers has problems such as corrosion failure. A strongly bonded friction-reducing and wear-resistant DLC coating for the surface of silicon carbide / silicon nitride and a preparation method thereof are proposed. By using a linear ion beam method, a serrated microstructure and an interfacial mixed layer are formed on the surface of the matrix, reducing the interface mismatch between the matrix and the DLC coating and significantly improving the film-substrate bonding force. Through the friction-reducing and wear-resistant effect of the DLC coating, the friction and wear performance of the silicon carbide / silicon nitride matrix is improved, and the service life of the components is increased.

[0005] The present invention provides a method for preparing a diamond-like carbon coating for the surface of a ceramic matrix, and the preparation method specifically includes the following steps: S1. Adopt the linear ion beam technology, use argon as the working gas, and etch the surface of the ceramic substrate with ionized argon ions to obtain a serrated microstructure; S2. Adopt the linear ion beam chemical vapor deposition method, use acetylene / methane as the working gas, ionize the hydrocarbon precursor on the surface of the etched ceramic substrate to form an interfacial mixed layer, and then deposit a diamond-like carbon coating to obtain a diamond-like carbon coating for the surface of the ceramic substrate.

[0006] Compared with the prior art, the present invention forms a serrated microstructure and an interfacial mixed layer on the surface of ceramic substrates such as silicon carbide / silicon nitride by the linear ion beam method, and directly deposits a strongly bonded DLC coating on the surface of the substrate by the linear ion beam.

[0007] In some embodiments, in the step S1, the material of the ceramic substrate is silicon carbide or silicon nitride.

[0008] In some embodiments, in the step S1, the ceramic substrate is pretreated before the etching treatment, and the specific steps of the pretreatment are as follows: after polishing the surface of the ceramic substrate, ultrasonically clean it with ethanol and acetone solution for 15 - 45 min respectively, and take it out and dry it.

[0009] In some embodiments, in the step S1, the parameters of the etching treatment are as follows: use argon as the working gas, apply a bias voltage of -50 to -500 V on the surface of the ceramic substrate, the ion source current is 0.1 - 1 A, the chamber pressure is 1 - 5×10 -5 Torr, the gas flow rate is 30 - 40 sccm, and use ionized argon ions to etch the surface of the substrate for 20 - 60 min.

[0010] In some embodiments, the specific steps in the step S2 are as follows: use acetylene / methane as the working gas, apply a bias voltage of -50 to -500 V on the etched ceramic substrate, the ion source current is 0.1 - 1 A, the chamber pressure is 1 - 5×10 -5 Torr, the gas flow rate is 30 - 40 sccm, and the deposition time is 15 - 1200 min.

[0011] The second object of the present invention is to provide a diamond-like carbon coating for the surface of a ceramic substrate. The diamond-like carbon coating is provided on the surface of the ceramic substrate. A serrated microstructure is formed on the surface of the ceramic substrate. An interfacial mixed layer is formed between the diamond-like carbon coating and the surface of the ceramic substrate. The phases in the diamond-like carbon coating include diamond phase and graphite phase.

[0012] In some embodiments, the thickness of the diamond-like carbon coating is 0.2 - 10 μm.

[0013] Furthermore, the bonding strength between the diamond-like carbon coating and the ceramic substrate is 50 - 80 N.

[0014] Furthermore, the friction coefficient of the diamond-like carbon coating is 0.05 - 0.07, and the wear rate is (0.9 - 1.1) * 10 - 8 mm 3 / (Nm).

[0015] Compared with the prior art, the present invention has the following advantages: (1) The ion beam etching process forms a microstructure and an interfacial mixing layer on the surface, reduces the influence of the interface mismatch between the substrate and the DLC coating, improves the film-substrate bonding strength, and enhances the supporting ability for the surface DLC coating to achieve high load-bearing; (2) The surface DLC coating has high smoothness and does not require subsequent polishing process. In addition, the DLC deposition process is simple and stable, and there is no need to introduce a metal transition layer to avoid corrosion and spalling, which is conducive to achieving long-term stable service. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a comparison chart of the bonding strength of depositing DLC on the surface of silicon carbide in Example 1, Example 2, and Comparative Example 1 of the present invention by different methods; Figure 2 is a comparison chart of the friction curves of unpolished diamond-coated modified silicon carbide and linearly ion beam deposited DLC-modified silicon carbide in Example 1 and Comparative Example 2 of the present invention; Figure 3 is a comparison chart of the wear rates of unpolished diamond-coated modified silicon carbide and linearly ion beam deposited DLC-modified silicon carbide in Example 1 and Comparative Example 2 of the present invention; Figure 4 is the cross-sectional morphology of the coating / substrate observed by TEM after FIB sample preparation in Example 1 of the present invention. Due to the Ar ion beam etching effect, a serrated microstructure is formed on the surface of the silicon carbide substrate; Figure 5 is a high-resolution transmission electron microscope image of the cross-section of the coating / substrate observed by TEM after FIB sample preparation in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] To make the above objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the protection scope of the claims of the present invention.

[0018] It should be noted that the endpoints and any values within the ranges disclosed in this document are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the values between the endpoints of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this document.

[0019] Unless otherwise defined, all terms, symbols, and other scientific terms used in this document are intended to have the same meaning as commonly understood by those skilled in the art to which this invention pertains. In some cases, for the purpose of clarification or convenience of citation, terms with commonly understood meanings are defined in this document, and such definitions in this document should not be construed as indicating a significant difference from the conventional understanding in the art. The technical methods described or cited in this document are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments follows the protocols and parameters provided by the manufacturers.

[0020] The technical effects of the present invention will be described below in conjunction with specific embodiments.

[0021] Example 1 This example provides a diamond-like carbon coating for the surface of a ceramic substrate, and the thickness of the diamond-like carbon coating is about 0.8 μm; The method for preparing the diamond-like carbon coating includes the following steps: S1. Polish the surface of the silicon carbide substrate, perform ultrasonic cleaning with ethanol and acetone solution for 30 minutes, and take it out for drying; S2. Adopt the linear ion beam technology, use argon as the working gas, apply a bias voltage of -200 V on the silicon carbide substrate, the ion source current is 0.2 A, the chamber pressure is 3×10 -5 Torr, the gas flow rate is 38 sccm, and use the ionized argon ions to etch the surface of the substrate, and this process is maintained for 30 minutes.

[0022] S3. Adopt the linear ion beam technology, use acetylene as the working gas, apply a bias voltage of -100 V on the silicon carbide substrate, the ion source current is 0.2 A, the chamber pressure is 3×10 -5 Torr, the gas flow rate is 38 sccm, the deposition time is 60 minutes, and deposit an amorphous carbon coating with a thickness of 0.8 μm on the silicon carbide surface.

[0023] The film-substrate adhesion force of the coating obtained above was tested by the scratch method to be 61.7 N. As Figure 1 shown, during the grinding process with a silicon carbide ball, the load is 10 N, and the average friction coefficient during the friction process is about 0.06. As Figure 2As shown, the wear rate is 1.5×10 -8 mm 3 / (Nm), as Figure 3 shown, showing excellent anti-friction and anti-wear properties.

[0024] Example 2 This example provides a diamond-like carbon coating for the surface of a ceramic substrate, and the thickness of the diamond-like carbon coating is about 2.8 μm.

[0025] The preparation method of the diamond-like carbon coating includes the following steps: S1. Polish the surface of the silicon carbide substrate, ultrasonically clean it with ethanol and acetone solutions for 30 minutes, and take it out and dry it; S2. Adopt the linear ion beam technology, use argon as the working gas, apply a bias voltage of -200 V on the silicon carbide substrate, the ion source current is 0.2 A, the chamber pressure is 3×10 -5 Torr, the gas flow rate is 38 sccm, and use the ionized argon ions to etch the surface of the substrate, and this process lasts for 30 minutes; S3. Adopt the linear ion beam technology, use acetylene as the working gas, apply a bias voltage of -100 V on the silicon carbide substrate, the ion source current is 0.2 A, the chamber pressure is 3×10 -5 Torr, the gas flow rate is 38 sccm, the deposition time is 210 minutes, and deposit an amorphous carbon coating with a thickness of 2.8 μm on the silicon carbide surface.

[0026] The film-substrate bonding strength of the coating obtained above is tested by the scratch method to be 56.1 N, as Figure 1 shown.

[0027] Comparative Example 1 This comparative example is a comparative example of Example 1. The difference is that in this Comparative Example 1, HiPIMS is used to deposit DLC with a graphite target with a purity of 99.99%, and the performance parameters of the silicon carbide substrate are the same as those in Example 1.

[0028] The preparation method of the DLC coating on the above-mentioned silicon carbide surface includes the following steps: S1. Polish the surface of the silicon carbide substrate, ultrasonically clean it with ethanol and acetone solutions for 20 minutes respectively, and take it out and dry it; S2. Adopt the HiPIMS technology. When the vacuum reaches 2×10 -5 Torr, set the working pressure of argon to 8 mTorr, and under the bias voltage with a voltage set to -800 V, a frequency of 50 kHz, and a duty cycle of 50%, etch the substrate through Ar + glow discharge for 30 min; S3. Using HiPIMS technology, deposit DLC with a graphite target of 99.99% purity. The parameters during the deposition process are as follows: the working pressure of argon gas is 0.8 mTorr, the HiPIMS voltage power supply, duty cycle, and frequency are set to -900 V, 1%, and 100 Hz respectively, and the deposition time is 60 minutes; The film-substrate adhesion of the coating obtained above was tested by the scratch method and found to be 8.8 N. As Figure 1 shown, compared with Example 1, the adhesion is only one-eighth.

[0029] Comparative Example 2 This comparative example is a comparative example of Example 1. The difference is that in this Comparative Example 2, only a diamond coating is prepared as the top layer, and the preparation steps of the diamond coating are as follows.

[0030] The preparation method of the above silicon carbide surface composite coating includes the following steps: S1. Grind the surface of the silicon carbide substrate using an aqueous solution of diamond micropowder with a particle size of 10 μm and a content of 5%, and grind on a grinding machine for 20 minutes; S2. Put the ground silicon carbide substrate into ethanol containing 1% of 10 nm diamond powder, ultrasonically clean for 30 minutes, and take it out and dry.

[0031] S3. Using hot filament plasma chemical vapor deposition technology, with methane / hydrogen / nitrogen as the working gas, the ratio is 1:100:0, the pressure is 1 kPa, the temperature is 600 °C, the distance between the tantalum wire and the substrate is 5 mm, and the deposition time is 5 hours. A 3 μm diamond coating with a grain size of 10 nm is formed on the surface of the substrate.

[0032] The initial friction coefficient of the coating obtained above when rubbing against a silicon carbide ball in a 3.5 wt% NaCl solution under a load of 5 N is 0.5, and the average friction coefficient after rubbing for one hour is 0.3. As Figure 1 shown; the wear rate is 3.01×10 -5 mm 3 / (Nm), as Figure 2 shown. Under the same friction conditions, compared with Example 1, the wear rate increases by three orders of magnitude.

[0033] From the above results, it can be seen that in the present invention, a serrated microstructure and an interfacial mixed layer are formed on the substrate surface by the linear ion beam method, reducing the interface mismatch between the substrate and the DLC coating and greatly improving the film-substrate adhesion. Through the friction-reducing and wear-resistant effects of the DLC coating, the friction and wear performance of the silicon carbide / silicon nitride substrate is improved, and the service life of the component is increased.

[0034] Although the present disclosure is disclosed as above, the scope of protection of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a diamond-like coating on a ceramic substrate surface, characterized in that: The preparation method specifically comprises the following steps: S1. Linear ion beam technology is used, argon is used as the working gas, and ionized argon ions are used to etch the surface of the ceramic substrate to obtain a sawtooth microstructure; S2. A linear ion beam chemical vapor deposition method is used with acetylene / methane as the working gas to ionize a hydrocarbon precursor on the surface of an etched ceramic substrate to form an interface mixed layer, and then a diamond-like coating is deposited to obtain a diamond-like coating for the surface of the ceramic substrate.

2. The preparation method according to claim 1, characterized in that In the step S1, the material of the ceramic matrix is ​​silicon carbide or silicon nitride.

3. The preparation method according to claim 1, characterized in that: In the step S1, the ceramic substrate is pretreated before etching, and the pretreatment steps are as follows: after polishing the surface of the ceramic substrate, ultrasonic cleaning is performed using ethanol and acetone solutions for 15 to 45 minutes respectively, and then the substrate is taken out and dried.

4. The preparation method according to claim 1, characterized in that: In step S1, the parameters of the etching process are as follows: argon is used as the working gas, a bias voltage of -50 to -500 V is applied to the surface of the ceramic substrate, the ion source current is 0.1 to 1 A, and the chamber pressure is 1 to 5×10 -5 Torr, the gas flow rate is 30~40 sccm, and the substrate surface is etched using ionized argon ions for 20~60min.

5. The preparation method according to claim 1, characterized in that: The specific steps in step S2 are as follows: using acetylene / methane as the working gas, applying a bias voltage of -50 to -500 V on the etched ceramic substrate, the ion source current is 0.1 to 1 A, and the chamber pressure is 1 to 5×10 -5 Torr, gas flow rate is 30~40 sccm, and deposition time is 15~1200min.

6. A diamond-like coating for a ceramic substrate surface prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The diamond-like coating is arranged on the surface of a ceramic substrate, the surface of the ceramic substrate forms a sawtooth microstructure, an interface mixed layer is formed between the diamond-like coating and the surface of the ceramic substrate, and the phases in the diamond-like coating include a diamond phase and a graphite phase.

7. The diamond-like coating according to claim 6, characterized in that The thickness of the diamond-like carbon coating is 0.2-10 μm.

8. The diamond-like coating according to claim 6, characterized in that The bonding force between the diamond-like carbon coating and the ceramic substrate is 50-80N.

9. The diamond-like coating according to claim 6, characterized in that The friction coefficient of the diamond-like coating is 0.05-0.07, and the wear rate is (0.9-1.1)*10 -8 mm 3 / (Nm).

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