Highly adhesive high-temperature-resistant composite coating and preparation method thereof

Abstract

This invention discloses a high-adhesion, high-temperature resistant composite coating and its preparation method, belonging to the field of surface thin film preparation technology. The method includes: micro-machining and etching a substrate material to form a periodic pattern on the substrate material surface; sandblasting; sputtering a tetrahedral amorphous carbon transition layer film on the substrate material surface; and continuing chemical vapor deposition to deposit a diamond protective film, thereby obtaining a high-adhesion, high-temperature resistant composite coating on the substrate material surface. This method can improve the nucleation rate of diamond on the substrate material and increase the bonding force between the diamond protective film and the substrate material. The tetrahedral amorphous carbon film can be bonded to different materials, such as metals, plastics, and inorganic non-metals, without the serious stress problem during deposition. Using tetrahedral amorphous carbon as a transition layer for the substrate material can increase the stability of diamond on the substrate material and effectively protect the substrate material's anti-oxidation and anti-corrosion properties at high temperatures.

Description

Technical Field

[0001] This invention relates to a high-bonding, high-temperature resistant composite coating and its preparation method, belonging to the field of surface thin film preparation technology. Background Technology

[0002] With the advancement of the times, the rapid development of all industries has entered a new chapter. Materials are the foundation of everything. The conditions for using materials in fields such as chemical engineering, human medicine, semiconductors, nuclear energy applications, and aerospace are becoming increasingly demanding, necessitating various methods for preparing special materials or enhancing the substrate through surface modification. Common forms of surface modification include applying coatings. Coatings can be classified according to function as: wear-resistant coatings, heat-resistant and oxidation-resistant coatings, atmospheric-resistant coatings, conductive coatings, resistive coatings, mechanical component coatings, and chemical corrosion-resistant coatings. Diamond is a special material with many excellent properties, such as superhardness, high-temperature resistance, corrosion resistance, and super wear resistance. Applying diamond as a coating to a substrate material can effectively enhance the substrate material's oxidation resistance, corrosion resistance, and wear resistance.

[0003] Research on high-temperature resistant coatings in my country started relatively late, and the coatings currently developed suffer from poor high-temperature stability, low adhesion to the substrate, and insufficient bonding strength. For example, when diamond is deposited on a substrate material, the bonding strength between the diamond and the substrate is not strong enough, resulting in high stress. During use, the diamond is prone to detachment, leading to a failure in the protection of the substrate material and causing functional loss. To solve this problem, it is necessary to improve the bonding strength between the diamond and the substrate material, reduce stress, and improve heat dissipation. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a high-bonding, high-temperature resistant composite coating and its preparation method, which enhances the bonding force between diamond and the substrate.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] In a first aspect, this application provides a method for preparing a high-adhesion, high-temperature resistant composite coating, comprising the following steps:

[0007] Micro-machining and etching are performed on the substrate material to form a periodic pattern on the surface of the substrate material;

[0008] The matrix material is sandblasted with diamond abrasive.

[0009] A tetrahedral amorphous carbon transition layer thin film is sputtered onto the surface of the substrate material;

[0010] A diamond protective film is chemically vapor-deposited on the tetrahedral amorphous carbon transition layer film, thereby obtaining the highly adhesive, high-temperature resistant composite coating on the surface of the substrate material.

[0011] The high-bonding, high-temperature resistant composite coating preparation method provided in this application first etches regular pits on the surface of the substrate material to facilitate the implantation of diamond sand during sandblasting. The implanted diamond sand is conducive to the nucleation of the tetrahedral amorphous carbon transition layer film and the diamond protective film. The tetrahedral amorphous carbon transition layer film is used to reduce the internal stress of the composite coating, which is conducive to the growth of the diamond protective film and to improving the bonding force between the diamond protective film and the substrate material. It fully utilizes the characteristics of the diamond protective film, such as high thermal conductivity, good mechanical properties and excellent chemical stability, to provide strong protection for the substrate material.

[0012] Furthermore, in the step of micromachining and etching the substrate material, pulsed laser etching is used. The pulsed laser power is between 20W and 1500W, the spot diameter is between 20μm and 800μm, the pulse width is between 2fs and 600ns, and the repetition frequency is between 2Hz and 10Hz. 10 Hz.

[0013] Furthermore, the periodic pattern includes circular pits located at the edge of the substrate material surface and rectangular pits arrayed within the area surrounded by the circular pits, the rectangular pits being parallel to each other.

[0014] Intermittent rectangular pits form regular nucleation points, which is conducive to the more uniform film formation of tetrahedral amorphous carbon transition layer films. Circular pits are conducive to making full use of the position of the substrate material edge, so that the substrate material edge also forms a good film.

[0015] Furthermore, in the step of sandblasting the matrix material with diamond sand, the particle size of the diamond sand is 10nm-70nm, and the sandblasting pressure is 0.7MPa-1.5MPa.

[0016] Besides nucleation, the implanted diamond abrasive also acts as an anchor in the tetrahedral amorphous carbon transition layer film, enhancing the bonding force between the tetrahedral amorphous carbon transition layer film and the diamond protective film. The particle size of the diamond abrasive should not be too large to ensure a relatively uniform and smooth composite coating. At the same time, the sandblasting pressure should be sufficient to achieve the effect of implanting grains; excessive sandblasting pressure will damage the periodic pattern.

[0017] Furthermore, in the step of sandblasting the matrix material with diamond sand, the processing time is 10-20 minutes.

[0018] Further, the step of sputtering to form a tetrahedral amorphous carbon transition layer thin film on the surface of the substrate material includes: placing the substrate material in a magnetically filtered arc ion plating apparatus, and evacuating the vacuum chamber to 1×10⁻⁶. -3 Pa-1×10 -4The substrate material negative bias voltage is 1000V-2000V, the duty cycle is 40%-80%, the frequency is 30kHz-100kHz, the graphite target current is 100A-500A, and the coating time is 10min-100min. Diamond sand grains are implanted in the periodic pattern. These process parameters are conducive to forming a high-quality tetrahedral amorphous carbon transition layer film.

[0019] Furthermore, before placing the substrate material into the magnetic filter arc ion plating equipment, the sample stage is wiped with alcohol; before vacuuming, argon gas is introduced to evaporate the alcohol; after vacuuming, argon gas is introduced to purge the substrate material.

[0020] Furthermore, in the step of chemically vapor depositing a diamond protective film on the tetrahedral amorphous carbon transition layer film, a microwave plasma chemical vapor deposition system, a hot filament chemical vapor deposition system, a combustion flame chemical vapor deposition system, or a direct current plasma jet chemical vapor deposition system is used. The amount of methane gas introduced is equivalent to 3%-7% of the amount of hydrogen gas introduced, the gas pressure is 60 Torr-120 Torr, the surface temperature of the substrate material is 700℃-1000℃, and the growth time is 3h-10h.

[0021] Furthermore, after chemical vapor deposition, the cooling rate before removal is less than 3℃ / s, which can effectively reduce the thermal stress between the matrix material and the diamond, and prevent the diamond from falling off the matrix material.

[0022] Secondly, this application provides a high-adhesion, high-temperature resistant composite coating, which is prepared by the high-adhesion, high-temperature resistant composite coating preparation method described in the first aspect.

[0023] Micromachining and sandblasting can give the substrate material a high density of nucleation sites. The tetrahedral amorphous carbon transition layer film can effectively improve the bonding force between the substrate material and diamond. This diamond composite coating can effectively give the substrate material high temperature resistance and greatly broaden the performance of the substrate material to be suitable for a variety of working environments.

[0024] The beneficial effects of this invention are: it allows diamond to be effectively deposited on the substrate material, increases the nucleation rate of diamond on the substrate material, increases the bonding force between the diamond protective film and the substrate material, and allows the tetrahedral amorphous carbon film to be bonded to different materials, such as metals, plastics, and inorganic non-metals, without causing serious stress problems during deposition. Using tetrahedral amorphous carbon as a transition layer for the substrate material can increase the stability of diamond on the substrate material and effectively protect the substrate material's anti-oxidation and anti-corrosion properties at high temperatures.

[0025] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0026] Figure 1 This is an optical microscope image of a molybdenum sheet after microprocessing under pulsed laser light, based on an implementation example.

[0027] Figure 2 This is an optical microscope image of the molybdenum sheet after a composite coating has been deposited, at the mask boundary in the implementation case.

[0028] Figure 3 This is an optical microscope image of an uncoated molybdenum sheet at high temperature, from an implementation case. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this invention.

[0030] It should be understood that, without conflict, any and all embodiments of the present invention can be combined with technical features of any other embodiment or multiple other embodiments to obtain other embodiments. The present invention includes such combinations to obtain other embodiments.

[0031] Unless otherwise specified, all technical and scientific terms used herein have the standard meaning in the field to which the claimed subject matter pertains. Where multiple definitions exist for a term, the definition herein shall prevail.

[0032] Diamond is one of the hardest known materials, with a hardness value far exceeding that of other materials. It possesses extremely high thermal conductivity, enabling it to rapidly conduct heat and effectively dissipate it, making it suitable for high-temperature and high-power applications. Diamond also exhibits excellent chemical stability, resisting corrosion from most chemicals. Even at very high temperatures, diamond does not undergo significant changes, making it a highly stable crystal. Furthermore, diamond has a low coefficient of friction, reducing frictional losses and energy loss. However, diamond deposition on certain substrate materials presents challenges in nucleation, preventing it from effectively protecting the substrate and hindering its ability to perform its high-temperature and corrosion-resistant properties. For example, when diamond films are deposited on molybdenum, the films easily detach.

[0033] This application provides a method for preparing a high-adhesion, high-temperature resistant composite coating, including the following steps:

[0034] S1: Micro-machining and etching of the substrate material to form a periodic pattern on the surface of the substrate material.

[0035] S2: Sandblasting the matrix material with diamond sand.

[0036] S3: A tetrahedral amorphous carbon transition layer film is formed by sputtering on the surface of the substrate material.

[0037] S4: A diamond protective film is chemically vapor-deposited on a tetrahedral amorphous carbon transition layer film, thereby obtaining a high-adhesion, high-temperature resistant composite coating on the substrate material surface.

[0038] The matrix material can be metal, inorganic non-metal, polymer, etc., and the morphology can be regular or irregular.

[0039] Tetrahedral amorphous carbon coating is a diamond-like coating with an sp3 bond content of 80%, enabling effective adhesion to various materials. While both tetrahedral amorphous carbon and diamond are carbon materials, tetrahedral amorphous carbon also contains sp2 bonds, resulting in inferior performance and quality compared to diamond. Furthermore, the preparation efficiency of tetrahedral amorphous carbon is slower than that of diamond deposition. This application uses tetrahedral amorphous carbon as a transition layer, solving the problems of difficult diamond nucleation and low adhesion on some substrate materials, and is expected to broaden the application of diamond protective films in medical, spark plug, and chemical industries.

[0040] The method in this application embodiment can improve the nucleation rate of diamond in the matrix material and increase the bonding force between the diamond film and the matrix material, so that the tetrahedral amorphous carbon transition layer film and the diamond protective film are combined. This not only does not reduce the performance of the matrix, but also broadens the application scenarios of the matrix material, and can slow down the oxidation of the matrix material at high temperatures.

[0041] In step S1, etching is performed using a pulsed laser with a power of 20W-1500W, a spot diameter of 20μm-800μm, a pulse width of 2fs-600ns, and a repetition frequency of 2Hz-10Hz. 10 Hz. The specific operation involves placing the substrate material on a horizontal worktable, focusing a pulsed laser onto the substrate material, and then performing periodic micro-etching on the substrate material using a pre-defined model in the software. The horizontal worktable must be kept clean and flat; it should be wiped with alcohol beforehand to remove any impurities. For example, the pre-defined model might be a circle with a radius of 0.1 cm at the edge of the substrate material, forming a circular pit after etching. Rectangles of 3 cm × 0.1 cm might be used at other locations on the substrate material, forming several etched shapes, i.e., rectangular pits, on the molybdenum surface through periodic micro-etching.

[0042] In step S2, the diamond abrasive implanted not only serves for nucleation but also acts as an anchor in the tetrahedral amorphous carbon transition layer film, enhancing the bonding force between the film and the substrate material. The particle size of the diamond abrasive should not be too large; preferably, it is 10nm-70nm, and the blasting pressure is 0.7MPa-1.5MPa. This ensures a relatively uniform and smooth composite coating, while the blasting pressure is sufficient to implant the grains. Excessive blasting pressure will damage the periodic pattern, while insufficient pressure will result in the diamond abrasive not being firmly implanted on the substrate surface, potentially loosening and detaching during the protective gas purging process required for the composite film deposition.

[0043] Similarly, the processing time for step S2 is 10-20 minutes to avoid sandblasting damaging the surface microstructure of the substrate material after etching.

[0044] In step S3, a tetrahedral amorphous carbon transition layer film is formed by magnetically filtered arc ion plating sputtering. The sample stage can be wiped with alcohol beforehand to prevent impurities from affecting the sputtering coating. Then, the substrate material is placed in the magnetically filtered arc ion plating equipment, argon gas is introduced for cleaning, the power is turned on, and the vacuum chamber is evacuated to 1×10⁻⁶. -3 Pa-1×10 -4 The substrate material is cleaned by introducing argon gas. The negative bias voltage of the substrate material is 1000V-2000V, the duty cycle is 40%-80%, the frequency is 30kHz-100kHz, the graphite target current is 100A-500A, and the deposition time is 10min-100min. The resulting tetrahedral amorphous carbon transition layer film has a thickness of 100nm-200nm, which is sufficient to cover the diamond abrasive without being too thick to prevent the composite film from detaching.

[0045] Step S4 can employ a microwave plasma chemical vapor deposition system, a hot filament chemical vapor deposition system, a combustion flame chemical vapor deposition system, or a direct current plasma jet chemical vapor deposition system, using methane as the raw material and hydrogen as the etching gas. The purity of the methane gas is not less than 6N, and the purity of the hydrogen gas is not less than 5N. In the embodiments of this application, the diamond film is grown on a tetrahedral amorphous carbon transition layer film. Compared with chemical vapor deposition of diamond film directly on the substrate material, the methane gas content is higher. Specifically, the amount of methane gas introduced is equivalent to 3%-7% of the amount of hydrogen gas introduced, the gas pressure is 60 Torr-120 Torr, the surface temperature of the substrate material is 700℃-1000℃, and the growth time is 3h-10h. Due to the periodically etched shape on the surface of the substrate material and the presence of a tetrahedral amorphous carbon transition layer film, the diamond deposited from C in methane begins to nucleate on the surface of molybdenum, which can enhance the adhesion between the diamond protective film and the surface of the substrate material. Finally, stop the methane supply, slowly reduce the hydrogen flow rate, slowly balance the internal and external gas pressure, control the cooling rate to be less than 3°C per second, and cool down to room temperature to prevent stress damage caused by thermal mismatch. Then remove the substrate material with the composite coating.

[0046] The embodiments of this application have the following characteristics:

[0047] 1. Micromachining of the substrate material: Circular patterns at the edges densely densify the nucleation sites, while rectangular patterns in the center enable large-area micromachining, which is convenient and quick. These two etching patterns increase the number of diamond nucleation sites on the substrate material, improving the nucleation rate and enhancing the bonding strength between layers.

[0048] Second, by processing the surface of the matrix material with diamond abrasive, the nucleation sites on its surface become more compact. Diamond abrasive with a particle size of 10nm-70nm is selected to make the nucleation site more compact without damaging the surface microstructure.

[0049] Third, the final diamond protective film has a dense structure and high strength, which can protect the base material, enhance the high temperature resistance and corrosion resistance of the base material, and make the application range of the base material more extensive.

[0050] IV. The tetrahedral amorphous carbon transition layer film located between the diamond protective film and the substrate material is a diamond-like coating with a diamond bond content of 80%. It has high bonding strength and low stress, and can be bonded to different materials, such as metals, plastics, and inorganic non-metals. It has a high degree of matching with diamond and excellent performance.

[0051] V. Diamond composite coatings are prepared using methane, hydrogen, and argon as raw materials. The raw materials and exhaust gases are non-toxic and harmless, easy to treat, highly environmentally friendly, and the raw materials are readily available.

[0052] Implementation Cases

[0053] First, a molybdenum sheet is placed on a horizontal worktable. A pulsed laser is focused onto the sheet, and then, using software modeling, a pre-defined pattern is created to perform periodic micro-etching on the molybdenum sheet. The pre-defined pattern includes a circle with a radius of 0.1 cm at the edge of the substrate material and a 3 × 0.1 cm rectangle at the center of the substrate material. At this point, the surface morphology of the molybdenum sheet is as follows: Figure 1 As shown, there is a regular array of etching stripes.

[0054] The substrate material is then subjected to 15 minutes of sandblasting with diamond abrasive particles of 50 nm at a sandblasting pressure of 1 MPa. Next, half of the treated molybdenum sheet is masked and placed in a magnetic filter arc ion plating apparatus, with the vacuum chamber evacuated to 5.5 × 10⁻⁶. -3 Argon gas was introduced for purging. The substrate material was negatively biased at 1500V, with a duty cycle of 50% and a frequency of 60kHz. The graphite target current was 320A, and the deposition time was 30 minutes. After the tetrahedral amorphous carbon transition layer film was prepared, the mask was removed, and the substrate material was placed on the sample stage in the microwave plasma chemical vapor deposition system. Hydrogen gas (7N purity) was introduced for ignition and heating. Specifically, the hydrogen flow rate was first slowly increased to 40 sccm, at which point the gas pressure was 5 Torr, for ignition. During heating, the hydrogen flow rate was increased to 400 sccm, the gas pressure to 90 Torr, the microwave power to 5000W, and the temperature to approximately 700℃. Methane gas (6N purity) was then introduced again, accounting for 6% of the hydrogen flow rate, and argon gas (5N purity) accounting for 2% of the hydrogen flow rate, at a gas pressure of 95 Torr. The surface temperature of the substrate was 890℃, and diamond was grown on the molybdenum substrate for 5 hours. Finally, stop the methane supply, slowly reduce the hydrogen flow rate, slowly balance the internal and external gas pressure, control the cooling rate to be less than 3°C per second, cool down to room temperature, and remove the coated substrate material.

[0055] The molybdenum sheets obtained above were placed in an air atmosphere at 900 degrees Celsius to test their antioxidant capacity. After 20 hours, if... Figure 2 As shown, the portion of the film without a deposited tetrahedral amorphous carbon transition layer ( Figure 2 The diamond on the right side of the middle section detached, causing oxidation, while the part that had undergone the growth of the composite coating ( Figure 2 The surface (left side) remains smooth with no oxide shedding. Then, from... Figure 3 It can be seen that the oxidation of molybdenum is very severe, indicating that the diamond composite coating on molybdenum enables it to exhibit high-temperature resistance, and the diamond has not detached. Figure 2 It can be seen that the coating boundary is distinct and complete, and the bonding force between the diamond and the molybdenum sheet is effectively improved.

[0056] The method in this application embodiment can increase the number of nucleation sites of diamond on the surface of the matrix material, increase the nucleation rate of diamond, achieve low stress and high bonding force, and make the connection between the matrix material and diamond tight. Under the protection of the diamond coating, the matrix material can achieve properties such as high temperature resistance and corrosion resistance.

[0057] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a high-adhesion, high-temperature resistant composite coating, characterized in that, Includes the following steps: Micro-machining and etching are performed on the substrate material to form a periodic pattern on the surface of the substrate material; The matrix material is sandblasted with diamond abrasive. A tetrahedral amorphous carbon transition layer thin film is sputtered onto the surface of the substrate material; A diamond protective film is chemically vapor-deposited on the tetrahedral amorphous carbon transition layer film, thereby obtaining the high-adhesion, high-temperature resistant composite coating on the surface of the substrate material. The periodic pattern includes circular pits located at the edge of the substrate material surface and rectangular pits arrayed within the area surrounded by the circular pits, the rectangular pits being parallel to each other; In the step of sandblasting the matrix material with diamond sand, the particle size of the diamond sand is 10nm-70nm, the sandblasting pressure is 0.7MPa-1.5MPa, and the treatment time is 10min-20min.

2. The method for preparing a high-bonding, high-temperature resistant composite coating according to claim 1, characterized in that, In the step of micromachining and etching the substrate material, pulsed laser etching is used. The pulsed laser power is 20W-1500W, the spot diameter is 20μm-800μm, the pulse width is 2fs-600ns, and the repetition frequency is 2Hz-10Hz. 10 Hz.

3. The method for preparing a high-bonding, high-temperature resistant composite coating according to claim 1, characterized in that, The step of sputtering a tetrahedral amorphous carbon transition layer film on the surface of the substrate material includes: placing the substrate material in a magnetic filter arc ion plating apparatus, and evacuating the vacuum chamber to 1×10⁻⁶. -3 Pa-1×10 -4 Pa, substrate negative bias voltage of 1000V-2000V, duty cycle of 40%-80%, frequency of 30kHz-100kHz, graphite target current of 100A-500A, coating time of 10min-100min.

4. The method for preparing a high-bonding, high-temperature resistant composite coating according to claim 3, characterized in that, Before placing the substrate material into the magnetic filter arc ion plating equipment, wipe the sample stage with alcohol; before evacuating, introduce argon gas to evaporate the alcohol; after evacuating, introduce argon gas to purge the substrate material.

5. The method for preparing a high-bonding, high-temperature resistant composite coating according to claim 1, characterized in that, In the step of chemically vapor-depositing a diamond protective film on the tetrahedral amorphous carbon transition layer film, a microwave plasma chemical vapor deposition system, a hot filament chemical vapor deposition system, a combustion flame chemical vapor deposition system, or a DC plasma jet chemical vapor deposition system is used. The amount of methane gas introduced is equivalent to 3%-7% of the amount of hydrogen gas introduced, the gas pressure is 60 Torr-120 Torr, the surface temperature of the substrate material is 700℃-1000℃, and the growth time is 3h-10h.

6. The method for preparing a high-adhesion, high-temperature resistant composite coating according to claim 5, characterized in that, After chemical vapor deposition, the cooling rate before removal is less than 3℃ / s.

7. A high-adhesion, high-temperature resistant composite coating, characterized in that, It is prepared by the high-bonding, high-temperature resistant composite coating preparation method according to any one of claims 1 to 6.

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