A hydrogen-containing carbon-based film with a high sp 3 C content and a method for preparing the same

Abstract

The present invention discloses a hydrogen-containing carbon-based film with a high sp<supgt;3< / supgt;C content and a preparation method thereof. The steps include placing a surface-treated conductive metal workpiece in a vacuum chamber of a vacuum coating device, where at least one magnetron target cathode and at least one ionization source electrode are installed in the vacuum chamber, and using plasma to etch and activate the surface of the conductive metal workpiece; first depositing a target material Me layer by magnetron sputtering, and then depositing a carbon-containing gradient layer Me / C layer of a mixture of the target material Me and C, so as to form a Me-Me / C transition layer; using at least one ionization source electrode to prepare a hydrogen-containing carbon-based coating with a thickness of 1 to 6 micrometers on the Me-Me / C transition layer, and obtaining a hydrogen-containing carbon-based film with a high sp<supgt;3< / supgt;C content. The growth rate of the hydrogen-containing carbon-based film with a high sp<supgt;3< / supgt;C content prepared by the method of the present invention reaches 100 to 150 nm / min, and the sp<supgt;3< / supgt;C volume content of the hydrogen-containing carbon-based coating exceeds 45%.

Description

Technical Field

[0001] The present invention relates to the technical field of metal surface modification, and particularly relates to a hydrogen-containing carbon-based film with a high sp 3 C content and a preparation method thereof. Background Art

[0002] In a hydrogen-containing carbon-based coating rich in sp 3 C, the H content is relatively high, which is different from traditional diamond-like carbon (DLC) films, but it is still a material composed of an amorphous composite structure in which sp 3 C bonds form a spatial network and contain sp 2 C. Like other DLCs, it has excellent physical, mechanical, chemical, optical, electrical, and thermal properties, especially high hardness, high resistance, low friction coefficient and other properties. In the fields of industrial tools, gears, bearings, seals, chemical engineering, etc. in advanced manufacturing with demanding wear and corrosion resistance requirements, the service life of components can be greatly improved by modifying them with carbon-based coatings. The wear and corrosion resistance of carbon-based coatings mainly depends on the sp 3 C content in the coating. To meet the coating requirements for higher wear and corrosion resistance, it is necessary to develop an economical and effective preparation technology for hydrogen-containing carbon-based coatings with a high sp 3 C content.

[0003] At present, various methods for preparing DLC coatings have been developed, and many methods have entered commercial applications. The mainstream technologies include physical vapor deposition using a carbon target as the main carbon source, such as TEER Company; and plasma-enhanced chemical vapor deposition using hydrocarbon gases as the carbon source, such as Balzers and Hauzer Companies. The equipment for preparing DLC coatings is very expensive, and the growth rate of DLC coatings is usually lower than 15 nm / minute, resulting in high preparation costs and low efficiency. In recent years, a large amount of research and development on DLC preparation technologies has also been carried out in China. Except for the industrial application of DLC prepared by a linear ion source, there are not many commercial applications. It is noted that Chinese Patent CN101701332A uses carbide formed on the surface of a magnetron electrode, and then the carbide sputtered from the surface and carbon substances are co-deposited on the surface to form a metal-doped DLC. This method is limited to only preparing metal-doped DLC coatings, but the amount of metal that can be incorporated is difficult to control, and the uniform consistency of the coating composition is difficult to guarantee. Similarly, CN108374148A discloses the preparation of DLC by poisoning the surface of a cathode arc target with a carbon-containing gas. Even if this method is successful, it can only prepare doped DLC coatings, and the components released from the target surface after poisoning are difficult to control. The sp 3 C content of the Cr-DLC coating deposited by using a columnar Cr target and a columnar carbon target in CN105525258A is low, and the coating cannot meet the surface hardness requirements for some applications.

[0004] In summary, the biggest problems existing in the current preparation of carbon-based coatings using columnar magnetron targets or techniques such as target surface poisoning are: (1) It is difficult to ensure the uniform consistency of the coating composition; (2) The sp 3 C content in the coating is relatively low, which is not conducive to the requirements of high wear resistance and high corrosion resistance. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the object of the present invention is to provide a hydrogen-containing carbon-based thin film with a high sp 3 C content and a preparation method thereof. By using a special magnetic field structure and a columnar magnetron electrode with a high-resistance carbon-based coating on the surface as an ionization source electrode, the ionization rate of hydrocarbon gas in the vacuum chamber is greatly increased, and it is used in cooperation with other traditional columnar magnetron electrodes without a carbon-based coating covering as a magnetron target cathode to prepare a hydrogen-containing carbon-based thin film with a high sp 3 C content and high performance.

[0006] The present invention solves the following main core technical problems: (1) The ionization source electrode is only used as an ionization source for hydrocarbon gas to avoid releasing the metal substances of the target; 2) Achieve a high degree of ionization of the hydrocarbon working gas around the target to prepare a carbon-based coating with a high sp 3 C content.

[0007] According to the currently recognized subsurface ion implantation mechanism for the stable formation of sp 3 C in DLC coatings, the incident energy of the ionized carbon ions (C + ) and their energy flux together determine the sp 3 C content in the growing coating. The incident energy is determined by the applied electric field (bias voltage) and the free formation of incident ions, etc., and the energy flux is mainly determined by the ionization rate. Therefore, the ionization rate of the hydrocarbon gas introduced into the vacuum chamber becomes the key to preparing a carbon-based coating with a high sp 3 C content. The method for the present invention to solve this core problem is to transform the traditional columnar magnetron target into an efficient ionization source, which only ionizes the surrounding gas and does not emit the composition substances of the target itself. To achieve this purpose, the following new design is carried out on the existing columnar magnetron target: 1) Redesign and layout the permanent magnet core inside the magnetron column target. In particular, utilize the pole shoe effect to greatly increase the magnetic field intensity of the circular ring on the cross-section perpendicular to the target axis on the target surface, and the magnetic field intensity tangent to the target surface and perpendicular to the target axis is designed to be 4000 - 8000 gauss. The magnetic rotation with a pole shoe structure forms a strong closed magnetic field, which strongly confines the charged particles, especially electrons, and greatly enhances the electron density on the target surface and Ar +Density. When they collide with hydrocarbon gases, the ionization rate of hydrocarbon gases around the target is greatly increased. 2) As the cathode, the surrounding cations bombard and sputter the target surface, and the substances on the target surface are sputtered out and collide with the surrounding atmosphere. Therefore, an a-C:H coating with a surface resistance exceeding 1 MΩ and a prefabricated thickness of ≥1 μm is formed on the target surface. When the surrounding high-energy cations bombard the cathode target surface, only carbon and hydrogen in the a-C:H coating are sputtered out on the surface. Even if some surrounding C + ions are redeposited on the target surface, the composition and properties of the a-C:H coating remain unchanged. In this way, the goal of the target as a single, efficient, and controllable ionization source is achieved. When combined with other columnar target cathodes or even arc targets in the vacuum chamber, high-sp 3 C-content and high-performance carbon-based coatings can be prepared.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides an efficient and low-cost method for preparing a hydrogen-containing carbon-based thin film with a high sp 3 C content, comprising the following steps:

[0010] S1. Etching and activation: Place the surface-treated conductive metal workpiece in the vacuum chamber of a vacuum coating device. At least one magnetron target cathode and at least one ionization source electrode are installed in the vacuum chamber. Apply a bipolar pulse bias voltage to the conductive metal workpiece, and turn on the ion source to etch and activate the surface of the conductive metal workpiece using plasma;

[0011] S2. Prepare the Me-Me / C transition layer using a magnetron target cathode: First deposit the target material Me layer on the surface of the etched and activated conductive metal workpiece by magnetron sputtering, and then deposit a carbon-containing gradient layer Me / C layer of the target material Me and C to form a Me-Me / C transition layer;

[0012] S3. Prepare a high-sp 3 C-type hydrogen-containing carbon-based coating: Use at least one ionization source electrode to prepare a hydrogen-containing carbon-based coating with a thickness of 1-6 μm on the Me-Me / C transition layer by PECVD method to obtain a hydrogen-containing carbon-based thin film with a high sp 3 C content.

[0013] As a specific technical solution of the present invention, the traditional columnar magnetron target cathode is transformed into a special columnar ionization source electrode.

[0014] Preferably, the surface of the ionization source electrode is covered with an a-C:H coating, the thickness of the a-C:H coating is ≥1 μm, and the surface resistance of the a-C:H coating is ≥1 MΩ. A closed magnetic field is formed in a ring perpendicular to the electrode axis on the surface of the ionization source electrode, and the magnetic field intensity of the closed magnetic field in the direction perpendicular to the electrode axis on the surface of the ionization source electrode is 4000 - 8000 Gauss.

[0015] As a specific technical solution of the present invention, the materials of the magnetron target cathode and the ionization source electrode are any metal or alloy.

[0016] Preferably, the materials of the magnetron target cathode and the ionization source electrode are selected from any one of titanium, chromium, tungsten, titanium-aluminum, chromium-aluminum or tungsten carbide.

[0017] As a specific technical solution of the present invention, during the etching activation in step S1, the pressure in the vacuum chamber is 0.05 - 0.15 Pa; the bipolar pulse bias voltage applied to the conductive metal workpiece is +10 V to +25 V for the positive electrode and -150 V to -250 V for the negative electrode, the frequency is 30 - 40 kHz, and the duty cycle is 40% - 60%; the DC arc current is maintained at 60 - 100 A during the etching activation; the etching activation time is 30 - 60 min, and the temperature of the etched conductive metal workpiece reaches 75 - 150 °C.

[0018] Preferably, the plasma is argon plasma.

[0019] As a specific technical solution of the present invention, the operation of preparing the Me-Me / C transition layer in step S2 is as follows: argon gas is introduced into the vacuum chamber and the pressure is maintained at 0.05 - 0.15 Pa, then the magnetron target cathode is started, the power of the magnetron target cathode is adjusted to be maintained at 4 - 5 kW and a Me layer with a thickness of 300 - 500 nm is deposited on the conductive metal workpiece; then the inflow rate of argon gas is maintained and the power of the magnetron target cathode is linearly reduced from 4 - 5 kW to 1 kW, while the inflow rate of the hydrocarbon working gas is linearly increased until the pressure in the vacuum chamber reaches 0.8 - 2.0 Pa, the ionization source electrode is started, the power of the ionization source electrode is linearly adjusted from 1.5 kW to 4.0 - 5.0 kW for magnetron sputtering, a bipolar pulse bias voltage is applied to the conductive metal workpiece, and when the thickness of the deposited carbon-containing gradient layer Me / C layer reaches 200 - 400 nm, the magnetron target cathode is turned off.

[0020] Preferably, the bipolar pulse bias voltage applied to the conductive metal workpiece is +10 V to +25 V for the positive electrode and -100 V to -200 V for the negative electrode, the frequency is 30 - 40 kHz, and the duty cycle is 40% - 60%.

[0021] Preferably, the hydrocarbon working gas is acetylene;

[0022] As a specific technical solution of the present invention, in step S3, to prepare high sp3 There are three ways to operate the hydrogen-containing carbon-based coating of type C, which are respectively:

[0023] Way 1: Maintain the inflow rate of argon in step S2 and adjust the inflow rate of the hydrocarbon working gas to keep the pressure in the vacuum chamber maintained at 0.8 - 2.0 Pa. Close the magnetron target cathode, and only keep the ionization source electrode with a power adjusted to 4.0 - 5.0 kW working. Apply a bipolar pulse bias voltage to the conductive metal workpiece for depositing the hydrogen-containing carbon-based coating;

[0024] Or, Way 2: Maintain the inflow rate of argon in step S2 and adjust the inflow rate of the hydrocarbon working gas to keep the pressure in the vacuum chamber maintained at 0.8 - 2.0 Pa. At the same time, use at least one magnetron target cathode and more than two ionization source electrodes with a power adjusted to 4.0 - 5.0 kW working. Apply a bipolar pulse bias voltage to the conductive metal workpiece for depositing the metal-doped hydrogen-containing carbon-based coating;

[0025] Or, Way 3: Maintain the inflow rate of argon in step S2, introduce a certain amount of non-metal component gas, and adjust the inflow rate of the hydrocarbon working gas to keep the pressure in the vacuum chamber maintained at 0.8 - 2.0 Pa. Close the magnetron target cathode, and only keep the ionization source electrode with a power adjusted to 4.0 - 5.0 kW working. Apply a bipolar pulse bias voltage to the conductive metal workpiece for depositing the non-metal-doped hydrogen-containing carbon-based coating.

[0026] Preferably, in step S3, for the bipolar pulse bias voltage applied to the conductive metal workpiece in the three ways, the positive electrode is +10V - +40V, the negative electrode is -350V - -600V, the frequency is 30 - 40 kHz, and the duty cycle is 40% - 60%.

[0027] Preferably, the vacuum chamber of the vacuum coating device is equipped with a magnetron target cathode, an ionization source electrode, and a coil for forming a closed magnetic field. The vacuum coating device also has an ion source and a bipolar pulse bias voltage power supply. The magnetron target cathode and the ionization source electrode adopt an intermediate frequency pulse AC power supply. The bipolar pulse bias voltage power supply for applying a bipolar pulse bias voltage to the conductive metal workpiece adopts a bipolar pulse DC power supply, with a negative pulse voltage of -100 - -750V, a positive pulse voltage of +10 - +40V, a frequency of 30 - 40 kHz, and a duty cycle of 40% - 60%.

[0028] In the second aspect, the present invention provides a hydrogen-containing carbon-based thin film with a high sp 3 C content, which is specifically prepared by adopting the above preparation method.

[0029] Compared with the prior art, the present invention provides a hydrogen-containing carbon-based thin film with a high sp 3 C content and a preparation method thereof, having the following beneficial effects:

[0030] The present invention prepares a hydrogenated carbon-based film with a high sp 3 C content by using a special ionization source electrode in cooperation with a traditional magnetron target cathode. The growth rate reaches 100-150 nm / min, and the sp 3 C volume content of the hydrogenated carbon-based coating exceeds 45%.

[0031] Since the magnetic field intensity tangent to the surface of the ionization source electrode and perpendicular to the electrode axis direction is greater than 4000 Gauss, the surface of the ionization source electrode is coated with an a-C:H coating with a thickness of at least 1 micron and a surface resistance exceeding 1 MΩ. By using the ionization source electrode so arranged as an independently controllable working gas ionization source, the strong closed magnetic field surrounding the electrode is combined with magnetron sputtering on the electrode surface, avoiding the adverse effects of cathode surface poisoning and unstable operation; more importantly, the ionization rate of the working gas is greatly improved, that is, the C + energy flux density bombarding the workpiece surface during deposition is enhanced, achieving the goal of efficiently and rapidly growing and preparing a high sp 3 C carbon-based coating. In addition, through the design combination of the metal layer and the carbon-containing gradient layer in the transition layer, the residual internal stress of the coating is effectively reduced, and a high film-substrate bonding force between the carbon-based coating and the workpiece substrate is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 is a schematic structural diagram of the ionization source electrode of the present invention;

[0034] Figure 2 is a schematic cross-sectional structural diagram of obtaining a hydrogenated carbon-based film on a conductive metal workpiece of the present invention;

[0035] Figure 3 is the XPS spectrum of the coating obtained in Example 1 of the present invention.

[0036] Reference numerals: 11, magnetic core; 12, conductive substrate; 13, a-C:H coating; 14, closed magnetic field; 21, conductive metal workpiece; 22, transition layer; 23, hydrogenated carbon-based coating. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0038] The present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0039] The vacuum coating apparatus used in the following embodiments is a conventional device, which has 6 magnetron targets and can be obtained through commercial channels. In the present invention, some of the magnetron targets are modified to be ionization source electrodes for decomposing the surrounding hydrocarbon gas; the remaining unmodified magnetron targets are used as magnetron target cathodes for sputtering the surface material of the target.

[0040] Example 1

[0041] In this embodiment, an M35 tool steel specimen is used as the metal conductive workpiece 21 and the preparation method of the present invention is adopted for surface treatment.

[0042] For easy understanding, the structure of the ionization source electrode adopted in this embodiment refers to Figure 1 , and the structure of the hydrogen-containing carbon-based film obtained refers to Figure 2 . Two magnetron target cathodes, four ionization source electrodes and a coil for forming a closed magnetic field are installed in the vacuum chamber of the vacuum coating apparatus. The vacuum coating apparatus also has an ion source and a bipolar pulse bias power supply. The magnetron target cathode and the ionization source electrode adopt an intermediate frequency pulse AC power supply. Two magnetron target cathodes share one intermediate frequency twin power supply, and every two ionization source electrodes share one intermediate frequency twin power supply; the material of the magnetron target cathode is chromium metal, which is a traditional target cathode structure; the conductive substrate 12 of the ionization source electrode is Cr, and the surface is covered with an a-C:H coating 13 with a thickness of 1.3 microns. The surface resistance of the a-C:H coating 13 exceeds 1 MΩ. A closed magnetic field 14 is formed in the ring on the surface of the ionization source electrode perpendicular to the electrode axis measured by a gaussmeter. The magnetic field intensity of the closed magnetic field 14 in the direction perpendicular to the electrode axis on the surface of the ionization source electrode is 5433 gauss. The bipolar pulse bias power supply for applying a bipolar pulse bias to the conductive metal workpiece 21 adopts a bipolar pulse DC power supply, with a negative pulse voltage of -100 to -750 V, a positive pulse voltage of +10 to +40 V, a frequency of 30 to 40 kHz, and a duty cycle of 40% to 60%.

[0043] Specifically, this embodiment provides an efficient and low-cost preparation method for a hydrogen-containing carbon-based film with a high sp 3 C content to perform surface treatment on the conductive metal workpiece 21, including the following steps:

[0044] S1. Etching activation: Ultrasonically clean the surface of a tool steel specimen with the grade of M35 on the GT-Cleaningsystem cleaning line, and then place it on the sample workbench in the vacuum chamber of the vacuum coating device. There are 2 magnetron target cathodes and 4 ionization source electrodes installed in the vacuum chamber. Close the vacuum chamber and pump the background vacuum to below 5x10 -3 Pa; Pass argon through the ion source to maintain the pressure in the vacuum chamber at 0.1 Pa, start the ion source to perform Ar + ion bombardment etching cleaning on the conductive metal workpiece 21 to obtain a clean workpiece surface. During this period, maintain the DC arc current at 80 A, the bipolar pulse bias voltage applied to the conductive metal workpiece 21 is +20 V for the positive electrode and -200 V for the negative electrode, the frequency is 35 kHz, and the duty cycle is 50%; After 45 minutes of ion etching, the temperature of the conductive metal workpiece reaches 100 °C, and turn off the ion source.

[0045] S2. Prepare the Cr-Cr / C transition layer 22 using the magnetron target cathode: Pass argon into the vacuum chamber and maintain the pressure at 0.1 Pa, then start the 2 magnetron target cathodes, adjust the power of the magnetron target cathode to 4.5 kW and deposit a 400-nm-thick Cr metal layer on the etched and activated conductive metal workpiece; Then maintain the argon flow rate and linearly reduce the power of the magnetron target cathode until 1 kW, while linearly increasing the inflow of acetylene gas until the pressure in the vacuum chamber reaches 1.2 Pa. Start the 2 ionization source electrodes and linearly adjust the power of the ionization source electrodes from 1.5 kW to 4.5 kW for magnetron sputtering to deposit a carbon-containing gradient layer Cr / C layer of a mixture of target materials Cr and C. During this period, apply a bipolar pulse bias voltage to the conductive metal workpiece, +20 V for the positive electrode and -150 V for the negative electrode, the frequency is 35 kHz, and the duty cycle is 50%; When the thickness of the deposited carbon-containing gradient layer Cr / C layer reaches 300 nm, the formation of the Cr-Cr / C transition layer 22 is completed, and turn off the 2 magnetron target cathodes.

[0046] S3. Prepare a high sp 3 C hydrogen-containing carbon-based coating 23: Maintain the argon flow rate in step S2 and adjust the inflow of acetylene gas to keep the pressure in the vacuum chamber at 1.2 Pa. Turn off the magnetron target cathode, and at the same time start the 4 ionization source electrodes with a power adjusted to 4.5 kW to work. Apply a bipolar pulse bias voltage to the conductive metal workpiece of +20 V for the positive electrode and -500 V for the negative electrode, the frequency is 35 kHz, and the duty cycle is 50%. Deposit for 60 min to prepare the hydrogen-containing carbon-based coating 23; At this point, a hydrogen-containing carbon-based thin film with a high sp 3 C content is formed on the M35 tool steel specimen.

[0047] The hardness was tested using a nanoindentation instrument (Anton Paar TTX-NHT3, Switzerland), with a load of 5 mN, a loading rate of 10 mN / min, and a holding time of 10 s. X-ray photoelectron spectroscopy (XPS, Thermo K-Alpha +, USA) with an incident photon energy of 1486.6 eV was used to analyze the ratio of the volume content of sp 3 C in the coating.

[0048] After testing, the carbon-based coating was a-C:H, with a thickness of 5.4 microns and a nano-hardness of 23.6 GPa. The XPS spectrum obtained from the coating test is shown in Figure 3 , and the volume content of sp 3 C was 55%.

[0049] Example 2

[0050] In this example, a titanium alloy specimen was used as the metal conductive workpiece 21 and the surface treatment was carried out using the preparation method of the present invention.

[0051] For ease of understanding, the structure of the ionization source electrode used in this example refers to Figure 1 , and the structure of the hydrogen-containing carbon-based thin film obtained refers to Figure 2 . The vacuum chamber of the vacuum coating device is equipped with 1 magnetron target cathode, 5 ionization source electrodes, and a coil for forming a closed magnetic field. The vacuum coating device also has an ion source and a bipolar pulse bias power supply. The magnetron target cathode and the ionization source electrodes use an intermediate frequency pulse AC power supply. The magnetron target cathode and one of the ionization source electrodes use a DC pulse power supply with a frequency of 3000 Hz and a duty cycle of 60%. The remaining 4 ionization source electrodes share 1 intermediate frequency twin power supply every 2; the material of the magnetron target cathode is titanium metal, which is a traditional target cathode structure; the conductive substrate 12 of the ionization source electrode is tungsten carbide, and the surface is covered with an a-C:H coating 13 with a thickness of 1.1 microns. The surface resistance of the a-C:H coating 13 exceeds 1 MΩ. A closed magnetic field 14 is formed in the ring on the surface of the ionization source electrode perpendicular to the electrode axis measured by a gaussmeter, and the magnetic field strength of the closed magnetic field 14 in the direction perpendicular to the electrode axis on the surface of the ionization source electrode is 4120 gauss. The bipolar pulse bias power supply for applying a bipolar pulse bias to the conductive metal workpiece 21 uses a bipolar pulse DC power supply, with a negative pulse voltage of -100 to -750 V, a positive pulse voltage of +10 to +40 V, a frequency of 30 to 40 kHz, and a duty cycle of 40% to 60%.

[0052] Specifically, this example provides an efficient and low-cost preparation method for a hydrogen-containing carbon-based thin film with a high sp 3 C content for surface treatment of the conductive metal workpiece 21, including the following steps:

[0053] S1. Etching activation: The titanium alloy specimen was ultrasonically cleaned on the GT-Cleaning system cleaning line, and then placed on the sample workbench in the vacuum chamber of the vacuum coating device. A magnetron target cathode and five ionization source electrodes were installed in the vacuum chamber. The vacuum chamber was closed and the background vacuum was pumped to 5x10 -3 Argon is introduced through the ion source to maintain the vacuum chamber pressure at 0.05Pa, and the ion source is started to implement Ar on the conductive metal workpiece 21 + Ion bombardment etching cleaning is performed to obtain a clean workpiece surface. During the process, the DC arc current is maintained at 60A, and the bipolar pulse bias applied to the conductive metal workpiece 21 is positive +10V, negative -150V, frequency 40kHz, and duty cycle 60%; after 30 minutes of ion etching, the temperature of the conductive metal workpiece reaches 78°C and the ion source is turned off.

[0054] S2. Preparation of Ti-Ti / C transition layer 22 using magnetron target cathode: argon gas is introduced into the vacuum chamber and the pressure is maintained at 0.05 Pa. Then, one magnetron target cathode is started, the power of the magnetron target cathode is adjusted to 5 kW, and a 300 nm thick Ti metal layer is deposited on the conductive metal workpiece after etching and activation. Then, the amount of argon gas introduced is maintained and the power of the magnetron target cathode is linearly reduced to 1 kW. At the same time, the amount of acetylene gas flowing in is linearly increased until the pressure of the vacuum chamber reaches 0.8 Pa. Two magnetron target cathodes are started. The ionization source electrode is linearly adjusted to perform magnetron sputtering at a power of 1.5 kW to 4 kW to deposit a carbon-containing gradient layer Ti / C layer of a mixture of target materials Ti and C. During this period, a bipolar pulse bias is applied to the conductive metal workpiece, with a positive pole of +10 V, a negative pole of -200 V, a frequency of 40 kHz, and a duty cycle of 60%. When the thickness of the deposited carbon-containing gradient layer Ti / C reaches 200 nm, the formation of the Ti-Ti / C transition layer 22 is completed, and the power of the magnetron target cathode is adjusted to 2.5 kW.

[0055] S3, preparation of high sp 3 C-type hydrogen-containing carbon-based coating 23: Maintain the amount of argon gas introduced in step S2 and adjust the amount of acetylene gas inflow to keep the pressure in the vacuum chamber at 0.8 Pa, and simultaneously start 5 ionization source electrodes with a power adjustment of 4 kW to work, apply a bipolar pulse bias of +10 V for positive electrode, -350 V for negative electrode, 40 kHz for frequency, 60% for duty cycle, and deposit for 40 min to prepare the hydrogen-containing carbon-based coating 23; thus, a high sp 3 C content hydrogen-containing carbon-based film.

[0056] The hardness was tested using a nanoindentation instrument (Anton Paar TTX-NHT3, Switzerland) with a load of 5 mN, a loading rate of 10 mN / min, and a holding time of 10 s. The X-ray photoelectron spectrometer (XPS, Thermo K-Alpha +, USA) with an incident photon energy of 1486.6 eV was used to analyze the ratio of the volume content of sp 3 C in the coating.

[0057] After detection, the carbon-based coating was a-C:H:Ti doped with titanium, with a thickness of 3.9 microns and a nano-hardness of 18.7 GPa. The volume content of sp 3 C in the coating was 46%.

[0058] Example 3

[0059] In this example, a stainless steel specimen was used as the metal conductive workpiece 21 and the surface treatment was carried out using the preparation method of the present invention.

[0060] For easy understanding, the structure of the ionization source electrode used in this example refers to Figure 1 , and the structure of the hydrogen-containing carbon-based thin film obtained refers to Figure 2 . The vacuum chamber of the vacuum coating device is equipped with 2 magnetron target cathodes, 4 ionization source electrodes, and coils for forming a closed magnetic field. The vacuum coating device also has an ion source and a bipolar pulse bias power supply. The magnetron target cathodes and ionization source electrodes use an intermediate frequency pulse AC power supply. The 2 magnetron target cathodes share 1 intermediate frequency twin power supply, and every 2 ionization source electrodes share 1 intermediate frequency twin power supply; the material of the magnetron target cathode is Ti50Al50 alloy, which is a traditional target cathode structure; the conductive substrate 12 of the ionization source electrode is titanium, and the surface is covered with an a-C:H coating 13 with a thickness of 1.2 microns. The surface resistance of the a-C:H coating 13 exceeds 1 MΩ. The Gaussian meter measures that a closed magnetic field 14 is formed in the ring on the surface of the ionization source electrode perpendicular to the electrode axis, and the magnetic field strength of the closed magnetic field 14 in the direction perpendicular to the electrode axis on the surface of the ionization source electrode is 7883 Gauss. The bipolar pulse bias power supply for applying a bipolar pulse bias to the conductive metal workpiece 21 uses a bipolar pulse DC power supply, with a negative pulse voltage of -100 to -750 V, a positive pulse voltage of +10 to +40 V, a frequency of 30 to 40 kHz, and a duty cycle of 40% to 60%.

[0061] Specifically, this example provides an efficient and low-cost preparation method for a hydrogen-containing carbon-based thin film with a high sp 3 C content to carry out surface treatment on the conductive metal workpiece 21, including the following steps:

[0062] S1. Etching activation: Ultrasonically clean the surface of the stainless-steel specimen on the GT-Cleaning system cleaning line, and then place it on the sample workbench in the vacuum chamber of the vacuum coating device. There are 2 magnetron target cathodes and 4 ionization source electrodes installed in the vacuum chamber. Close the vacuum chamber and pump the background vacuum to below 5x10 -3 Pa; Introduce argon gas through the ion source to maintain the pressure in the vacuum chamber at 0.15 Pa, start the ion source to perform Ar + ion bombardment etching and cleaning on the conductive metal workpiece 21 to obtain a clean workpiece surface. During this period, maintain the DC arc current at 100 A, apply a bipolar pulse bias voltage of +25 V for the positive electrode and -250 V for the negative electrode to the conductive metal workpiece 21, with a frequency of 30 kHz and a duty cycle of 40%; After 60 minutes of ion etching, the temperature of the conductive metal workpiece reaches 147 °C, and then turn off the ion source.

[0063] S2. Prepare the Ti50Al50-Ti50Al50 / C transition layer 22 using the magnetron target cathode: Introduce argon gas into the vacuum chamber and maintain the pressure at 0.15 Pa. Then start the 2 magnetron target cathodes, adjust the power of the magnetron target cathode to 4.5 kW and deposit a 500-nm-thick Ti50Al50 alloy layer on the etched and activated conductive metal workpiece; Then maintain the inflow of argon gas and linearly reduce the power of the magnetron target cathode until it reaches 1 kW, while linearly increasing the inflow of acetylene gas until the pressure in the vacuum chamber reaches 1.9 Pa. Start the 2 ionization source electrodes and linearly adjust the power of the ionization source electrodes from 1.5 kW to 4.5 kW for magnetron sputtering to deposit a carbon-containing gradient layer Ti50Al50 / C layer mixed with Ti50Al50 and C on the conductive metal workpiece. During this period, apply a bipolar pulse bias voltage to the conductive metal workpiece, +10 V for the positive electrode and -100 V for the negative electrode, with a frequency of 40 kHz and a duty cycle of 40%; When the thickness of the deposited carbon-containing gradient layer Ti50Al50 / C layer reaches 400 nm, the formation of the Ti50Al50-Ti50Al50 / C transition layer 22 is completed, and then turn off the 2 magnetron target cathodes.

[0064] S3. Prepare the high sp 3 C hydrogenated carbon-based coating 23: Maintain the inflow of argon gas in step S2, adjust the inflow of acetylene gas and introduce 50 sccm of nitrogen gas to keep the pressure in the vacuum chamber at 1.9 Pa. At the same time, start the 4 ionization source electrodes with a power adjusted to 5 kW to work, apply a bipolar pulse bias voltage of +40 V for the positive electrode and -600 V for the negative electrode to the conductive metal workpiece, with a frequency of 30 kHz and a duty cycle of 45%, and deposit for 50 min to prepare the hydrogenated carbon-based coating 23; So far, a hydrogenated carbon-based thin film with a high sp 3 C content is formed on the stainless-steel specimen.

[0065] The hardness was tested using a nanoindenter (Anton Paar TTX-NHT3, Switzerland), with a load of 5 mN, a loading rate of 10 mN / min, and a holding time of 10 s. The X-ray photoelectron spectrometer (XPS, Thermo K-Alpha +, USA) with an incident photon energy of 1486.6 eV was used to analyze the volume content ratio of sp 3 C in the coating.

[0066] After testing, the carbon-based coating was nitrogen-doped a-C:H:N, with a thickness of 5.1 microns and a nano-hardness of 20.3 GPa. The volume content of sp 3 C in the coating was 51%.

[0067] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

[0068] In addition, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a hydrogen-containing carbon-based thin film with high sp 3 C content It is characterized in that it includes the following steps: S1. Etching activation: Place the surface-treated conductive metal workpiece in the vacuum chamber of a vacuum coating device. The pressure in the vacuum chamber is 0.05 Pa to 0.15 Pa. At least one magnetron target cathode and at least one ionization source electrode are installed in the vacuum chamber. Apply a bipolar pulse bias voltage to the conductive metal workpiece, with the positive electrode at +10 V to +25 V, the negative electrode at -150 V to -250 V, the frequency at 30 kHz to 40 kHz, and the duty cycle at 40% to 60%. Turn on the ion source and use argon plasma to etch and activate the surface of the conductive metal workpiece for 30 min to 60 min. The temperature of the etched conductive metal workpiece reaches 75 °C to 150 °C; S2. Prepare the Me-Me / C transition layer using the magnetron target cathode: First deposit a 300 nm to 500 nm thick target material Me layer on the surface of the etched and activated conductive metal workpiece by magnetron sputtering, and then deposit a 200 nm to 400 nm thick carbon-containing gradient layer Me / C layer of the target material Me and C to form the Me-Me / C transition layer; During the magnetron sputtering process, maintain the argon pressure at 0.05 Pa to 0.15 Pa, linearly reduce the power of the magnetron target cathode from 4 kW to 5 kW to 1 kW, and at the same time linearly increase the inflow rate of the hydrocarbon working gas until the pressure in the vacuum chamber reaches 0.8 Pa to 2.0 Pa. Start the ionization source electrode and linearly adjust the power of the ionization source electrode from 1.5 kW to 4.0 kW to 5.0 kW for magnetron sputtering. During this period, apply a bipolar pulse bias voltage to the conductive metal workpiece, with the positive electrode at +10 V to +25 V, the negative electrode at -100 V to -200 V, the frequency at 30 kHz to 40 kHz, and the duty cycle at 40% to 60%; S3. Preparation of high sp 3 C hydrogen-containing carbon-based coating: Use at least one ionization source electrode to deposit a hydrogen-containing carbon-based coating with a thickness of 1-6 microns on the Me-Me / C transition layer by PECVD method. In the hydrogen-containing carbon-based coating, the volume content of sp 3 C is 46%-55% to obtain a hydrogen-containing carbon-based thin film with a high sp 3 C content; during deposition, the pressure in the vacuum chamber is maintained at 0.8 Pa-2.0 Pa, the power of the ionization source electrode is 4.0 kW-5.0 kW, and a bipolar pulse bias voltage is applied to the conductive metal workpiece during this period, with the positive electrode +10 V-+40 V and the negative electrode -350 V--600 V, the frequency is 30 kHz-40 kHz, and the duty cycle is 40%-60%; Among them, the surface of the ionization source electrode is covered with an a-C:H coating with a thickness ≥ 1 μm and a surface resistance ≥ 1 MΩ; A closed magnetic field is formed in the ring perpendicular to the electrode axis on the surface of the ionization source electrode, and the magnetic field intensity of the closed magnetic field in the direction perpendicular to the electrode axis on the surface of the ionization source electrode is 4000 Gauss to 8000 Gauss.

2. The preparation method of a hydrogen-containing carbon-based thin film with high sp 3 C content It is characterized in that the materials of the magnetron target cathode and the ionization source electrode are metal or alloy.

3. The preparation method of the hydrogen-containing carbon-based film with high sp 3 C content It is characterized in that the materials of the magnetron target cathode and the ionization source electrode are selected from any one of titanium, chromium, tungsten, titanium-aluminum, chromium-aluminum, or tungsten carbide.

4. The preparation method of the hydrogen-containing carbon-based film with high sp 3 C content It is characterized in that during the etching activation in step S1, maintain the DC arc current at 60 A to 100 A during the etching activation.

5. The preparation method of the hydrogen-containing carbon-based film with high sp 3 C content It is characterized in that in step S2, the hydrocarbon working gas is acetylene.

6. The preparation method of a hydrogen-containing carbon-based film with a high sp 3 C content It is characterized in that In step S3, the operation of preparing a high sp 3 hydrogen-containing carbon-based coating of class C is as follows: Method 1: Maintain the inflow rate of argon in step S2 and adjust the inflow rate of the hydrocarbon working gas to keep the pressure in the vacuum chamber maintained at 0.8 Pa to 2.0 Pa. Turn off the magnetron target cathode and only keep the ionization source electrode with a power adjusted to 4.0 kW to 5.0 kW working. Apply a bipolar pulse bias voltage to the conductive metal workpiece to deposit and prepare a hydrogen-containing carbon-based coating; Alternatively, Method 2: Maintain the argon gas flow rate in Step S2 and adjust the inflow rate of the hydrocarbon working gas to keep the pressure in the vacuum chamber at 0.8 Pa to 2.0 Pa. At the same time, use at least one magnetron target cathode and more than two ionization source electrodes with a power adjusted to 4.0 kW to 5.0 kW to work, and apply a bipolar pulse bias voltage deposition to the conductive metal workpiece to prepare a metal-doped hydrogen-containing carbon-based coating; Or, Method 3: Maintain the argon gas flow rate in Step S2, introduce a certain amount of non-metallic component gas, and adjust the inflow rate of the hydrocarbon working gas to keep the pressure in the vacuum chamber at 0.8 Pa to 2.0 Pa. Turn off the magnetron target cathode, and only keep the ionization source electrodes with a power adjusted to 4.0 kW to 5.0 kW to work, and apply a bipolar pulse bias voltage deposition to the conductive metal workpiece to prepare a non-metal-doped hydrogen-containing carbon-based coating.

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