Preparation method of composite diamond-like carbon coating by arc electron enhanced deposition and composite diamond-like carbon coating

Abstract

The invention provides a preparation method of an arc light electron enhanced deposition composite diamond-like coating, which comprises the following steps: S1, heating a substrate, and then carrying out ion cleaning on the substrate; s2, depositing a metal bottom layer on the surface of the substrate; s3, depositing a transition layer on the surface of the substrate obtained in the step S2; and S4, starting an arc ion source and an auxiliary anode electrode, switching a bias power supply into an intermediate-frequency bipolar pulse power supply, and depositing the diamond-like carbon coating on the surface of the substrate obtained in the step S3. The invention further provides the composite diamond-like carbon coating. According to the method, the arc ion source and the auxiliary anode power supply are turned on, so that electrons frequently collide with the gas in the vacuum chamber, the ionization rate of the gas is greatly improved, the ultra-high-density plasma far superior to that of a traditional PECVD method is generated, and the deposition rate of the DLC coating is improved.

Description

Technical Field

[0001] This invention relates to the field of vacuum coating technology, and in particular to a method for preparing a lone photoelectron-enhanced deposition composite diamond-like coating and the composite diamond-like coating itself. Background Technology

[0002] Diamond-like carbon (DLC) coatings, with their superior hardness, low coefficient of friction, and excellent wear resistance, have been widely used in machinery manufacturing, the automotive industry, and other fields. Among existing fabrication processes, plasma-enhanced chemical vapor deposition (PECVD) is the mainstream method for preparing DLC ​​coatings. PECVD primarily utilizes different plasma excitation sources such as radio frequency (RF), microwave (MW), or intermediate frequency (MF) to achieve vapor deposition, which can, to a certain extent, meet the coating requirements of conventional workpieces.

[0003] However, the traditional PECVD preparation methods mentioned above still have significant limitations in practical applications. Specifically, the plasma density under conventional excitation modes is generally low, resulting in a slow deposition rate and low production efficiency. At the same time, some excitation sources (such as radio frequency) may pose radiation hazards, and the uniformity of the film layer is difficult to control.

[0004] The aforementioned problems make it difficult for the PECVD method to simultaneously meet the dual requirements of high deposition rate and high-quality film performance for large workpieces or complex structural components. Therefore, there is an urgent need to develop a more advanced method for preparing DLC ​​coatings. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a method for preparing an arc electron-enhanced deposition composite diamond-like coating, which can improve the deposition rate of the diamond-like coating and prepare a high-quality composite diamond-like coating.

[0006] In view of this, this application provides a method for preparing an arc-electron-enhanced deposition composite diamond-like coating, comprising the following steps:

[0007] S1. Place the substrate in the vacuum chamber of the coating equipment, evacuate the vacuum chamber, heat the substrate, introduce an inert gas into the vacuum chamber, and then perform ion cleaning on the substrate.

[0008] S2. Deposit a metal underlayer on the substrate surface;

[0009] S3. Deposit a transition layer on the substrate surface obtained in step S2;

[0010] S4. Turn on the arc ion source and auxiliary anode electrode, switch the bias power supply to a medium-frequency bipolar pulse power supply, and deposit a diamond-like coating on the substrate surface obtained in step S3.

[0011] In some specific embodiments, in step S1, the vacuum level of the vacuum chamber is 5.0 × 10⁻⁶. -2 The pressure is above Pa, and / or the heating temperature is 120~180℃ for 30~90min, and / or the inert gas includes high-purity argon, and the pressure of the inert gas introduced into the vacuum chamber is 1×10⁻⁶. -1 Pa ~ 8.0 × 10 -1 Pa; and / or, the negative bias voltage of the ion cleaning is 500~1000V, and the time is 30~40min.

[0012] In some specific embodiments, in step S2, the method for depositing the metal underlayer is specifically as follows:

[0013] Turn on the metal target sputtering power supply to deposit a metal underlayer on the substrate surface, and control the power of the sputtering power supply to be 2~10kW and the bias voltage to be 100~500V; the metal target includes a chromium target or a titanium target.

[0014] And / or, the thickness of the metal substrate is 50~100nm.

[0015] In some specific embodiments, in step S3, the deposited transition layer specifically comprises:

[0016] S31. An amorphous carbon transition layer is deposited on the substrate surface obtained in step S2;

[0017] S32. Deposit a transitional diamond-like layer on the substrate surface obtained in step S31;

[0018] Alternatively, S33, deposit a metal nitride transition layer on the substrate surface obtained in step S2;

[0019] S34. Deposit a metal carbide transition layer on the substrate surface obtained in step S33.

[0020] In some specific embodiments, in step S31, the gas source for depositing the amorphous carbon transition layer includes acetylene and methane; during the deposition of the amorphous carbon transition layer, the metal target sputtering power supply is turned off, the bias power supply is turned on, and the negative bias voltage is controlled to be 300~1000V; and / or, the deposition time is 10~30min; and / or, the thickness of the amorphous carbon overcoating layer is 50~100nm.

[0021] In step S32, during the deposition of the transition diamond-like carbon layer, the gas pressure is adjusted to 3 × 10⁻⁶. -1 ~9.0×10 - 1 Pa, apply a mid-frequency negative bias voltage of 500~900V, the deposition time is 10~60min, and / or the thickness of the transition diamond-like layer is 100~1000nm.

[0022] In some specific embodiments, in step S33, the gas source for depositing the metal nitride transition layer includes nitrogen gas, and the metal target sputtering power supply is turned on during the deposition of the metal nitride transition layer. The metal target is a chromium target or a titanium target, and the palladium power is controlled at 1~5kW and the negative bias voltage is 100~800V; and / or, in step S34, the gas source for depositing the metal carbide transition layer includes acetylene, and the metal target sputtering power supply is turned on during the deposition of the metal carbide. The metal target is a chromium target or a titanium target.

[0023] In some specific embodiments, in step S4, the frequency of the intermediate frequency bipolar pulse power supply is 40kHz~200kHz, and / or the output voltage of the intermediate frequency bipolar pulse power supply is 500~1000kW, and / or the duty cycle of the positive and negative pulses of the intermediate frequency bipolar pulse power supply is 1:1~1:5, and / or the negative pulse voltage of the positive and negative pulses of the intermediate frequency bipolar pulse power supply is 500~900V, and the positive pulse voltage is 10~40V; and / or the number of auxiliary anode electrodes is 1~3, and / or the auxiliary anode is copper or stainless steel with a polished surface, and / or the auxiliary anode electrode is fixed to the inner wall of the vacuum chamber, and / or the angle between the auxiliary anode electrode and the arc ion source is 90°~180°.

[0024] In some specific embodiments, in step S2, the arc ion source and the auxiliary anode power supply are turned on simultaneously, the current of the arc ion source is 40~100A, and the current of the auxiliary anode power supply is 40~100A; and / or, in step S3, the arc ion source and the auxiliary anode power supply are turned on simultaneously, the current of the arc ion source is 40~100A, and the current of the auxiliary anode power supply is 40~100A.

[0025] This application also provides a composite diamond-like coating prepared by the aforementioned preparation method, comprising a metal underlayer, a transition layer, and a diamond-like coating formed on the surface of a substrate.

[0026] In some specific embodiments, the transition layer includes an amorphous carbon transition layer formed on the surface of the metal substrate and a transition diamond-like layer formed on the surface of the amorphous carbon transition layer, or a metal nitride transition layer formed on the surface of the metal substrate and a metal carbide transition layer formed on the surface of the metal nitride transition layer.

[0027] This application provides a method for preparing an arc-enhanced electron deposition composite diamond-like carbon (DLC) coating. First, the surface of the substrate is ion-cleaned. Then, a metal underlayer is deposited on the surface of the substrate to reduce the difference in thermal expansion coefficients between the substrate and the DLC coating. Next, a transition layer is deposited on the surface of the metal underlayer to achieve a hardness gradient transition in the composite coating and reduce the stress difference between the DLC coating and the metal underlayer. Finally, a high-density electron flow is generated by arc discharge using an arc ion source and an auxiliary anode electrode. The electrons collide frequently with the gas in the vacuum chamber, which greatly improves the ionization rate of the gas, thereby generating an ultra-high-density plasma that far exceeds that of the traditional PECVD method. The high-density plasma means that more active carbon ions participate in film formation, which can improve the deposition rate of the DLC coating. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the preparation process of the arc-electronic enhanced deposition diamond-like carbon coating (DLC coating) of the present invention;

[0029] Figure 2 This is a schematic diagram of the preparation of the diamond-like carbon coating of the present invention;

[0030] Figure 3 SEM image of the metal substrate in the composite diamond-like coating prepared in Example 7;

[0031] Figure 4 SEM image of the metal substrate in the composite diamond-like coating prepared in Example 8. Detailed Implementation

[0032] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0033] Given the slow deposition rate, poor coating quality, and radiation hazards of existing diamond-like carbon (DLC) coatings, this application provides a method for preparing an arc-electron-enhanced deposition composite DLC coating. The method involves first ion cleaning of the substrate, then depositing a metal underlayer on the substrate surface, followed by a transition layer, and finally depositing the DLC coating. This method, with its sequential preparation of the metal underlayer, transition layer, and DLC coating, ensures adhesion between the coating and the substrate while reducing stress differences between layers and preventing stress concentration. This guarantees the quality of the composite DLC coating. Furthermore, the introduction of an arc ion source and an auxiliary anode electrode during the DLC deposition process improves the deposition rate. The mid-frequency bipolar pulse source and arc source are suitable for high-efficiency coating of large workpieces and avoid the use of strong radiation excitation sources such as RF and MW, resulting in a safer production environment. Specifically, the method for preparing an arc-electron-enhanced deposition composite DLC coating includes the following steps:

[0034] S1. Place the substrate in the vacuum chamber of the coating equipment, evacuate the vacuum chamber, heat the substrate, introduce an inert gas into the vacuum chamber, and then perform ion cleaning on the substrate.

[0035] S2. Deposit a metal underlayer on the substrate surface;

[0036] S3. Deposit a transition layer on the substrate surface obtained in step S2;

[0037] S4. Turn on the arc ion source and auxiliary anode electrode, switch the bias power supply to a medium-frequency bipolar pulse power supply, and deposit a diamond-like coating on the substrate surface obtained in step S3.

[0038] In the preparation method of arc electron-enhanced deposition composite diamond-like carbon coating, the substrate is first pretreated to prepare for subsequent metal underlayer deposition. Specifically, the substrate is first pre-cleaned, then heated, and finally ion-cleaned. After degreasing and cleaning, the substrate is placed on a workpiece rack in the vacuum chamber of the coating equipment to remove impurities such as oil, dust, and sweat from the substrate surface, ensuring clean contact between the substrate and the subsequent coating. Fixing the substrate to the rack ensures stable stress on the substrate and uniform coating in all areas during the coating process. If residual oil remains on the substrate surface, it will evaporate into gas during vacuum heating, leading to defects such as pinholes and bubbles in the coating. The fixed rack prevents uneven film thickness caused by substrate displacement during coating. In this application, the substrate can be a workpiece to be coated, a substrate to be coated, or a part to be coated.

[0039] After the substrate has undergone the above preliminary cleaning, the vacuum chamber is evacuated to 5.0 × 10⁻⁶. -2Above a certain temperature (Pa), the heater of the coating equipment is turned on to heat the substrate to 120-180°C and maintain this temperature for 30-90 minutes. Vacuuming removes impurities such as oxygen and nitrogen from the air in the coating equipment. Heating the substrate removes adsorbed moisture and residual gases from the substrate surface, preventing impurities (such as oxygen) from reacting with the carbon source to generate CO / CO2, which could lead to insufficient carbon content and decreased hardness in the coating. Specifically, the heating temperature is 130-150°C, maintained for 60-80 minutes.

[0040] During the ion cleaning process, inert gas is introduced into the vacuum chamber, and the process gas pressure is controlled at 1.0 × 10⁻⁶. -1 Pa ~ 8.0 × 10 -1 A negative bias voltage of 500V~1000V is applied to the workpiece for 30min~40min of ion cleaning. During this process, the inert gas is specifically selected from high-purity argon. The injected argon ions bombard the substrate surface at high speed, causing micro-roughening of the substrate surface, increasing the contact area between the coating and the substrate, and further enhancing the adhesion. High-energy argon ions can activate atoms on the substrate surface, improving the interfacial bonding activity between the subsequent metal underlayer and the substrate. The gas pressure is 3.0×10⁻⁶. -1 Pa ~ 5.0 × 10 -1 The negative bias voltage is 700~900V, and the ion cleaning time is 35~38min. If the negative bias voltage is too low, the ion energy is insufficient, resulting in poor cleaning and inability to effectively remove the adsorption layer and weak boundary layer on the substrate surface. If the voltage is too high, it will cause excessive sputtering and ion damage to the substrate surface, forming a rough surface, and may even cause the substrate to heat up too quickly, generating thermal stress. If the cleaning time is too short, the cleaning is incomplete, and residual contaminants lead to poor coating adhesion. If the time is too long, it will cause substrate material loss, excessive surface roughness, and may also form stress concentration points. The gas pressure affects the plasma density and the ion mean free path. If the gas pressure is low, the ion mean free path is long, the bombardment energy is high, and the cleaning is more intense, thus affecting the cleaning effect.

[0041] After ion cleaning of the substrate surface, step S2 is performed to deposit a metal underlayer on the substrate surface. This metal underlayer provides an ideal bonding surface for the diamond-like carbon (DLC) coating, improving the adhesion between the DLC coating and the substrate surface, and acts as a stress buffer layer to alleviate the high internal stress of the DLC. Specifically, the method for depositing the metal underlayer is as follows:

[0042] Turn on the metal target sputtering power supply to deposit a metal underlayer on the substrate surface, control the target power to be 2~10kW and the bias voltage to be 100~500V; the metal target includes a chromium target or a titanium target; the thickness of the metal underlayer is 50~100nm.

[0043] More specifically, high-purity argon gas is continuously introduced, and the metal target sputtering power supply (the metal target is a chromium target or a titanium target) is turned on. The target power is controlled at 2~10kW and the bias voltage at 100V~500V to deposit a 50nm~100nm thick metal underlayer on the substrate surface. Chromium or titanium are highly bonding metals with good compatibility with most metal substrates (such as steel and aluminum alloys) and subsequent amorphous carbon transition layers. This reduces the difference in thermal expansion coefficients between the substrate and the DLC coating, preventing cracking of the coating due to thermal deformation. The 50nm~100nm thickness ensures good bonding without causing stress accumulation in the underlayer itself due to excessive thickness, thus preventing the metal underlayer from detaching. Conversely, too thin a layer would result in insufficient stress buffering. Specifically, the power is 4~8W, more specifically, 5~7W. The bias voltage is 200~400V, more specifically, the bias voltage is 250~350V. The bias voltage makes the bottom layer have better density and improves the bonding force with the substrate. An appropriate bias voltage can realize the ion plating effect. At the same time, ion bombardment gives the deposited atoms higher energy and enhances their migration ability, forming a dense, fine-grained bottom layer, improving the bonding strength and barrier performance.

[0044] In step S3, a transition layer is deposited on the substrate surface. During this process, the transition layer comprises an amorphous carbon transition layer and a transition diamond-like layer, or a metal nitride transition layer and a metal carbide transition layer, or a metal nitride transition layer and a transition diamond-like layer; specifically, the deposited transition layer is:

[0045] S31. An amorphous carbon transition layer is deposited on the substrate surface obtained in step S2;

[0046] S32. Deposit a transitional diamond-like layer on the substrate surface obtained in step S31;

[0047] Alternatively, S33, deposit a metal nitride transition layer on the substrate surface obtained in step S2;

[0048] S34. Deposit a metal carbide transition layer on the substrate surface obtained in step S33;

[0049] Alternatively, S33, deposit a metal nitride transition layer on the substrate surface obtained in step S2;

[0050] S34' Deposit a transitional diamond-like layer on the substrate surface obtained in step S33.

[0051] The method for depositing the above-mentioned amorphous carbon transition layer and transition diamond-like carbon layer is more specifically as follows:

[0052] Turn off the metal target sputtering power supply, turn on the bias power supply, control the negative bias voltage to 300~1000V, and introduce high-purity acetylene or methane into the vacuum chamber. Deposit for 10~30min to form an amorphous carbon transition layer with a thickness of 50nm~100nm. The hardness and toughness of amorphous carbon are between those of the metal substrate and the DLC coating, which can achieve a gradient transition of hardness, reduce the stress difference between the diamond-like carbon coating and the metal substrate, and avoid concentrated cracking of the coating.

[0053] Maintaining a constant volume ratio of argon to acetylene or methane, adjust the process gas pressure to 3.0 × 10⁻⁶. -1 Pa ~ 9.0 × 10 - 1 Pa, continue to apply a mid-frequency negative bias voltage of 500V~900V, and deposit for 10min~60min to form a transition DLC layer with a thickness of 100nm~1000nm. The transition DLC layer is deposited by traditional PECVD method. It has a dense structure and few defects. It can serve as a buffer substrate to avoid the subsequent arc-enhanced high-speed deposition from directly affecting the transition layer and causing defects in the film. The thickness of 100nm~1000nm can be adjusted according to the substrate requirements, providing a smooth and clean deposition surface for the subsequent DLC main layer. The transition DLC layer already has some DLC characteristics (such as low friction coefficient) and can complement the main layer to improve the overall wear resistance of the coating.

[0054] A transition layer is formed between the diamond-like carbon (DLC) coating and the metal substrate to achieve a smooth transition in chemical composition, mechanical properties, and coefficient of thermal expansion from the metal substrate to the DLC layer, avoiding interface aging caused by abrupt performance changes. Specifically, a gradient transition layer (e.g., metal → metal carbide → carbon-rich carbide → DLC) is formed by continuously or stepwise changing the flux ratio of metal (e.g., Cr, Ti, Si) to carbon. This compositional gradient can smooth changes in elastic modulus and coefficient of thermal expansion, greatly reducing interfacial shear stress. The deposition time of the amorphous carbon transition layer is 15-20 minutes, and the thickness is 60-80 nm. The deposition thickness of the amorphous carbon transition layer is designed to ensure effective transition, but excessive thickness will increase internal stress.

[0055] During the deposition of the transition DLC layer, the gas pressure is specifically 4.0 × 10⁻⁶. -1 Pa ~ 7.0 × 10 -1 Pa, the intermediate frequency negative bias voltage is specifically 600~800V, and the deposition time is specifically 20~40min.

[0056] The specific methods for depositing the metal nitride transition layer and the metal carbide transition layer described above are as follows:

[0057] S33. Deposit a metal nitride transition layer on the substrate surface obtained in step S2;

[0058] S34. Deposit a metal carbide transition layer on the substrate surface obtained in step S33.

[0059] In step S33 above, the gas source for depositing the metal nitride transition layer includes nitrogen. During the deposition of the metal nitride transition layer, the metal target sputtering power supply is turned on. Specifically, the metal target is a titanium target or a chromium target, and the palladium power is controlled at 1~5kW, and the negative bias voltage is 100~800V; specifically, the power is 2~4kW, and the negative bias voltage is 200~600V. In step S34 above, the metal target sputtering power supply is kept on during the deposition of the metal carbide transition layer. The metal target is a titanium target or a chromium target, and the gas source for depositing the metal carbide transition layer includes acetylene or methane.

[0060] The specific methods for depositing the aforementioned metal nitride transition layer and transition diamond-like carbon layer are as follows:

[0061] Alternatively, S33, deposit a metal nitride transition layer on the substrate surface obtained in step S2;

[0062] S34' Deposit a transitional diamond-like layer on the substrate surface obtained in step S33.

[0063] In step S33 above, the gas source for depositing the metal nitride transition layer includes nitrogen gas. During the deposition of the metal nitride transition layer, the metal target sputtering power supply is turned on. Specifically, the metal target is a titanium target or a chromium target, and the palladium power is controlled at 1~5kW, with a negative bias voltage of 100~800V; specifically, the power is 2~4kW, and the negative bias voltage is 200~600V; in step S34' above, the gas pressure is specifically 4.0×10⁻⁶. -1 Pa ~ 7.0 × 10 -1 Pa, the intermediate frequency negative bias voltage is specifically 600~800V, and the deposition time is specifically 20~40min.

[0064] After the transition layer is prepared, the diamond-like carbon (DLC) coating is prepared. In step S4, the arc ion source and auxiliary anode electrode are turned on, and the bias power supply is switched to a medium-frequency bipolar pulse power supply to deposit the DLC coating on the substrate surface obtained in step S3. More specifically, the schematic diagram of the above method for depositing the DLC coating is shown below. Figure 2 As shown, specifically:

[0065] Maintaining the flow of argon and acetylene or methane, and keeping the process gas pressure constant, turn on the arc ion source and auxiliary anode power supply, controlling the arc ion source current to 40A~100A and the auxiliary anode current to 40A~100A. Simultaneously, switch the workpiece rotating frame bias power supply to a 40kHz~200kHz medium-frequency bipolar pulse power supply, controlling the negative pulse voltage to 500V~750V and the reverse positive pulse voltage to 10V~40V, depositing and forming the DLC main layer. An ion shielding plate is installed at the front end of the arc ion source, made of high-temperature resistant stainless steel, to completely block the ions emitted by the arc ion source, and a 5~10m margin is reserved on the side of the ion shielding plate. The vacuum chamber features a wide electron release channel with 1-3 auxiliary anodes made of copper or stainless steel with a polished surface. These anodes are fixed to the inner wall of the vacuum chamber via an insulating support. The installation angle between the auxiliary anodes and the arc ion source is 90°-180°. The output power of the medium-frequency bipolar pulse power supply is 50kW-150kW, and the duty cycle (positive:negative) of the positive and negative pulses is adjustable between 1:1 and 1:5. The output frequency of the bipolar pulse power supply is 40kHz-200kHz. The bipolar pulse power supply can provide a negative pulse voltage of 500V-750V and a positive pulse voltage of 10V-40V to the workpiece rotating frame.

[0066] The system includes an arc ion source that generates a high-density electron flow (3-4 times higher than traditional PECVD plasma density), providing sufficient energy for acetylene gas ionization (increasing carbon ion concentration and accelerating deposition); an ion shield that completely blocks metal ions emitted by the ion source, preventing metal impurities from mixing into the DLC coating and ensuring coating purity, allowing only electrons to pass through; an auxiliary anode that generates an electric field with a current of 40A-100A, guiding electrons to collide with acetylene gas in the vacuum chamber, significantly improving the acetylene ionization rate (further increasing carbon ion concentration, and increasing the deposition rate from the traditional 1μm / h to over 2.5μm / h); a layout of 1-3 anodes that ensures the electric field uniformly covers the vacuum chamber, avoiding film thickness differences caused by uneven local plasma density; and a polished anode surface that reduces electron loss and ensures electric field stability.

[0067] Furthermore, the negative pulse voltage is 500V~750V to guide high-density carbon ions to deposit onto the substrate surface, ensuring the spline properties of the DLC coating. 3 The hybridization ratio maintains high hardness; specifically, the negative pulse voltage is 650~700V. The negative pulse voltage adjusts the sp... 3 / sp 2 The ratio reduces the internal stress of the coating, which is beneficial to improving hardness and adhesion; if the negative pulse voltage is too high, the high-energy ion bombardment effect ("subsurface injection" model) will increase the sp 3The formation of bonds results in high hardness and high elastic modulus ta-C (tetrahedral amorphous carbon) or hard aC:H, but at the same time it will significantly increase compressive stress, which may lead to coating peeling. If the negative pulse voltage is too low, the deposition energy barrier is low, mainly forming sp² bonds, and the coating is softer (such as graphite).

[0068] The reverse positive pulse voltage is 10V~40V. The above-mentioned reverse positive pulse is used to neutralize excess electrons on the substrate surface, avoid abnormal discharge caused by electron accumulation, and reduce defects such as pinholes and microcracks on the coating surface; specifically, the positive pulse voltage is 20~30V.

[0069] The angle between the auxiliary anode electrode and the arc ion source is specifically 100~160°, and more specifically, the angle between the auxiliary anode electrode and the arc ion source is specifically 120~140°.

[0070] The frequency of the intermediate frequency bipolar pulse power supply is 40kHz~200kHz to shorten the pulse period, so that ion deposition and electron neutralization alternate rapidly, ensuring the stability of the deposition process; specifically, the frequency is 60~180kHz, more specifically, the frequency is 100~150kHz.

[0071] The output power of the medium-frequency bipolar pulse power supply is 50kW~200kW, and the duty cycle of the positive and negative pulses is 1:1~1:5. To adapt to different substrate sizes (larger workpieces require higher power), the deposition rate and coating quality are balanced by adjusting the duty cycle. Specifically, the output power is 80~150kW, more specifically, the output power is 100~120kW. Specifically, the duty cycle of the positive and negative pulses is 1:1.5~1:4.

[0072] Specifically, the above steps can maintain a constant gas pressure in the vacuum chamber, and through the combination of an arc ion source, an auxiliary anode, and a bipolar pulse power supply, rapid and high-quality deposition of the DLC master layer can be achieved.

[0073] To further improve the internal stress, friction coefficient, and stability of diamond-like carbon (DLC) coatings, other elements can be introduced during the deposition process. For example, metal doping (such as W, Ti, Cr) can form Me-DLC, which can significantly reduce internal stress and improve toughness and thermal conductivity, but the hardness will decrease. It is often used in high-load anti-friction applications. Non-metal doping (such as Si, F, N) can reduce internal stress and friction coefficient and improve hydrophobicity. F doping can provide extremely low surface energy (increasing water and oil content).

[0074] Furthermore, in steps S2 and S3 above, the arc ion source and the auxiliary anode power supply are simultaneously activated, respectively. The current of the arc ion source is independently 40-100A, and the current of the auxiliary anode is independently 40-100A; specifically, the current of the arc ion source is independently 50-80A, and the current of the auxiliary anode is independently 50-80A. Adding the above-mentioned arc ion source and auxiliary anode power supply to the metal substrate and transition layer increases the density of the metal substrate and transition layer. In particular, adding the arc ion source and auxiliary anode power supply to the metal nitride transition layer increases the nitrogen content of the metal nitride transition layer, which can be increased from 3% to 15%.

[0075] In the preparation process of the above-mentioned composite diamond-like coating, the parameters of each step are interrelated and mutually restrictive.

[0076] After the diamond-like carbon coating is deposited, all power supplies and gas valves are turned off. Once the temperature in the vacuum chamber drops below 80°C, the vacuum is broken and the coated product is removed, thus ending the coating process. This avoids the rapid entry of air due to the vacuum being broken at high temperatures, which could cause oxidation on the substrate surface. Furthermore, slow cooling can release residual stress between the coating and the substrate, preventing cracking of the coating due to excessive temperature differences.

[0077] As described above, this application provides a method for preparing an arc-electron-enhanced deposition composite diamond-like carbon coating, wherein the specific preparation process of one type of composite diamond-like carbon coating is as follows: Figure 1 As shown, the process includes the following steps performed sequentially: workpiece pretreatment - transferring the workpiece to the vacuum chamber - evacuating and heating the vacuum chamber - injecting high-purity argon gas for ion cleaning of the workpiece - turning on the metal target sputtering power supply to deposit the metal underlayer - turning off the metal target sputtering power supply, injecting high-purity acetylene to form a transition layer - applying a medium-frequency negative bias voltage to form a transition DLC layer - turning on the arc ion source and auxiliary anode power supply to form the DLC main layer - turning off the power supply and gas valves to remove the workpiece.

[0078] This application also provides a composite diamond-like coating prepared by the above preparation method, comprising a metal underlayer, a transition layer and a diamond-like coating formed on the surface of a substrate.

[0079] Furthermore, the transition layer includes an amorphous carbon transition layer formed on the surface of the metal substrate and a transition diamond-like layer formed on the surface of the amorphous carbon transition layer, or a metal nitride transition layer formed on the surface of the metal substrate and a metal carbide transition layer formed on the surface of the metal nitride transition layer.

[0080] This application provides a method for preparing a composite diamond-like carbon (DLC) coating. In the DLC coating preparation step, an arc ion source and an auxiliary anode electrode are activated. A high-density electron flow is generated using arc discharge. Electrons collide frequently with acetylene gas in the vacuum chamber, significantly increasing the gas ionization rate. This produces ultra-high-density plasma far exceeding that of traditional PECVD methods. The high-density plasma means more active carbon ions participate in film formation, which can improve the deposition rate of the DLC coating. Simultaneously, the bias power supply is switched to a medium-frequency bipolar pulsed power supply. The medium-frequency power supply and arc source technology make it easier to amplify power and adjust the vacuum chamber size, making it ideal for efficient coating of large workpieces. Furthermore, this method avoids the use of excitation sources with strong radiation, such as RF and MW, resulting in a safer production environment.

[0081] To further understand the present invention, the preparation method of the arc electron-enhanced deposition composite diamond-like coating provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0082] Example 1

[0083] 1. Pretreatment:

[0084] The end mill was ultrasonically cleaned in acetone and ethanol solutions for 15 minutes each to thoroughly remove oil stains from the surface of the end mill.

[0085] 2. Coating process:

[0086] Step 1: Install the cleaned end mill onto the workpiece stand;

[0087] Step 2: Evacuate the vacuum chamber to 5.0 × 10⁻⁶. -2 Above Pa, then turn on the heater to heat the end mill to 150°C and hold for 60 minutes to remove water vapor and other gases adsorbed on the surface of the end mill;

[0088] Step 3: Introduce 99.99% pure high-purity argon gas into the vacuum chamber until the pressure in the vacuum chamber is 0.5 Pa. Turn on the bias power supply and apply an 800V DC pulse bias voltage to perform ion bombardment cleaning on the workpiece for 35 minutes to further activate and clean the workpiece surface.

[0089] Step 4: Keep argon gas flowing in, turn on the sputtering power supply of the chromium target, control the target power to 4kW, negative bias voltage to 300V, and deposit for 20 minutes to form a dense chromium metal underlayer of about 80nm thick on the surface of the end mill, so as to enhance the adhesion of the subsequent DLC film layer.

[0090] Step 5: Turn off the chromium target power supply, introduce high-purity acetylene gas with a purity of 99.99% into the vacuum chamber, control the volume ratio of argon to acetylene to be 1:2, turn on the bias power supply, negative bias voltage of 500V, deposit for 20 minutes to form an amorphous carbon transition layer with a thickness of about 70nm to relieve stress.

[0091] Step 6: Keep the gas ratio constant, adjust the gas pressure to 0.5 Pa, apply a 700 V mid-frequency negative bias voltage, and deposit for 40 min to form a transition DLC layer with a thickness of about 500 nm, in preparation for high-speed deposition of the main layer;

[0092] Step 7: Keep the gas supply and pressure constant, turn on the arc ion source and auxiliary anode power supply, control the arc ion source current to 70A, and simultaneously switch the workpiece rotating frame bias power supply to a 100kHz medium frequency bipolar pulse power supply with an output voltage of 700V. Control the negative pulse voltage to 700V and the reverse positive pulse voltage to 30V. The duty cycle of the positive and negative pulses is 30% for the negative pulse and 20% for the positive pulse. Do not output pulses during the remaining cycle time. A stainless steel baffle is installed at the front end of the arc ion source, with an 8-20mm wide electron release channel reserved on its side to block ions and release electrons. At the same time, turn on two copper auxiliary anodes with an angle of approximately 120° between the auxiliary anodes and the arc ion source. Control the anode current to 70A. Deposit for 120 minutes under these conditions to form a dense and smooth DLC master layer of approximately 5μm thickness at high speed.

[0093] Step 8: After deposition is complete, turn off the acetylene gas, argon gas, arc ion source, auxiliary anode and all power supplies in sequence; after the vacuum chamber temperature cools down to below 80°C, fill the vacuum chamber with high-purity nitrogen gas to atmospheric pressure, and take out the end mill with the coating completed.

[0094] Examples 2-6

[0095] The preparation method is basically the same as in Example 1, except that the arc ion source current and the auxiliary anode current are adjusted, and the corresponding change of the bias current on the end mill surface is shown in Table 1. The deposition rate of the DLC main layer is shown in Table 1.

[0096] Table 1. Data on arc ion source current, auxiliary anode current, and deposition rate in the embodiments.

[0097]

[0098] As shown in Table 1, during the deposition of DLC coating, the introduction of auxiliary anode current can significantly increase the bias current. The increase in bias current is equivalent to the increase in plasma flow density on the end mill surface, thereby improving the deposition rate of diamond-like carbon coating. Furthermore, if the auxiliary anode current is low, the increase in the deposition rate of diamond-like carbon coating is not significant.

[0099] Example 7

[0100] The preparation method is basically the same as in Example 1, except that: in step five, a metal nitride transition layer is formed by magnetron sputtering. The specific process is as follows:

[0101] Step 5: Turn on the chromium target sputtering power supply (4kW), introduce high-purity argon and nitrogen gas in a ratio of 1:3 into the vacuum chamber, maintain a vacuum level of 0.3Pa, turn on the bias power supply (400V negative bias), and deposit for 60 minutes to form a 300nm~400nm thick chromium nitride transition layer.

[0102] Figure 3 The images show SEM images of the metal substrate and metal nitride transition layer in the composite diamond-like coating prepared in this embodiment. As can be seen from the images, the grain size of the metal substrate prepared in this embodiment is 1~2μm.

[0103] Example 8

[0104] The preparation method is basically the same as in Example 7, except that in step five, an arc ion enhancement is used to deposit a metal nitride transition layer based on magnetron sputtering, as detailed below:

[0105] Step 5: Turn on the chromium target sputtering power supply (4kW), introduce high-purity argon and nitrogen gas in a 1:3 ratio into the vacuum chamber, maintain a vacuum level of 0.3Pa, turn on the bias power supply (400V negative bias), and simultaneously turn on the arc ion source and auxiliary anode power supply. Control the arc ion source current to 70A and the auxiliary anode current to 60A, and deposit for 60 minutes to form a 300nm~400nm thick chromium nitride transition layer.

[0106] Figure 4 The image shows an SEM image of the metal substrate in the composite diamond-like coating prepared in this embodiment. As can be seen from the image, the grain size of the metal substrate prepared in this embodiment is 100~200nm, and the surface density is significantly improved.

[0107] contrast Figure 3 and Figure 4 The introduction of an arc ion source and an auxiliary anode power source into the metal substrate, metal nitride layer, and metal carbide transition layer significantly improves the ionization rate of nitrogen and acetylene. The nitrogen and carbon content in the film layer is greatly increased to 10-20%at. Furthermore, the increased ionization rate makes the metal substrate more compact and the grain size significantly reduced from 1-2μm in diameter to 100-200nm.

[0108] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0109] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an arc-electron-enhanced deposition composite diamond-like carbon coating, comprising the following steps: S1. Place the substrate in the vacuum chamber of the coating equipment, evacuate the vacuum chamber, heat the substrate, introduce an inert gas into the vacuum chamber, and then perform ion cleaning on the substrate. S2. Deposit a metal underlayer on the substrate surface; S3. Deposit a transition layer on the substrate surface obtained in step S2; S4. Turn on the arc ion source and auxiliary anode electrode, switch the bias power supply to a medium-frequency bipolar pulse power supply, and deposit a diamond-like coating on the substrate surface obtained in step S3.

2. The preparation method according to claim 1, characterized in that, In step S1, the vacuum level in the vacuum chamber is 5.0 × 10⁻⁶. -2 The pressure is above Pa, and / or the heating temperature is 120~180℃ for 30~90min, and / or the inert gas includes high-purity argon, and the pressure of the inert gas introduced into the vacuum chamber is 1×10⁻⁶. -1 Pa ~ 8.0 × 10 -1 Pa; and / or, the negative bias voltage of the ion cleaning is 500~1000V, and the time is 30~40min.

3. The preparation method according to claim 2, characterized in that, In step S2, the method for depositing the metal underlayer is specifically as follows: A metal target sputtering power supply is turned on to deposit a metal underlayer on the substrate surface. The power of the sputtering power supply is controlled to be 2~10kW and the bias voltage is 100~500V. The metal target includes a chromium target or a titanium target. And / or, the thickness of the metal substrate is 50~100nm.

4. The preparation method according to claim 1, characterized in that, In step S3, the deposition transition layer specifically comprises: S31. An amorphous carbon transition layer is deposited on the substrate surface obtained in step S2; S32. Deposit a transitional diamond-like layer on the substrate surface obtained in step S31; Alternatively, S33, deposit a metal nitride transition layer on the substrate surface obtained in step S2; S34. Deposit a metal carbide transition layer on the substrate surface obtained in step S33.

5. The preparation method according to claim 4, characterized in that, In step S31, the gas source for depositing the amorphous carbon transition layer includes acetylene and methane. During the deposition of the amorphous carbon transition layer, the metal target sputtering power supply is turned off, the bias power supply is turned on, and the negative bias voltage is controlled to be 300~1000V; and / or, the deposition time is 10~30min; and / or, the thickness of the amorphous carbon overcoating layer is 50~100nm. In step S32, during the deposition of the transition diamond-like carbon layer, the gas pressure is adjusted to 3 × 10⁻⁶. -1 ~9.0×10 -1 Pa, apply a mid-frequency negative bias voltage of 500~900V, the deposition time is 10~60min, and / or the thickness of the transition diamond-like layer is 100~1000nm.

6. The preparation method according to claim 4, characterized in that, In step S33, the gas source for depositing the metal nitride transition layer includes nitrogen gas, and the metal target sputtering power supply is turned on during the deposition of the metal nitride transition layer. The metal target is a chromium target or a titanium target, and the palladium power is controlled at 1~5kW and the negative bias voltage is 100~800V; and / or, in step S34, the gas source for depositing the metal carbide transition layer includes acetylene, and the metal target sputtering power supply is turned on during the deposition of the metal carbide. The metal target is a chromium target or a titanium target.

7. The preparation method according to claim 4, characterized in that, In step S4, the frequency of the intermediate frequency bipolar pulse power supply is 40kHz~200kHz, and / or the output voltage of the intermediate frequency bipolar pulse power supply is 500~1000kW, and / or the duty cycle of the positive and negative pulses of the intermediate frequency bipolar pulse power supply is 1:1~1:5, and / or the negative pulse voltage of the positive and negative pulses of the intermediate frequency bipolar pulse power supply is 500~900V, and the positive pulse voltage is 10~40V; and / or the number of auxiliary anode electrodes is 1~3, and / or the auxiliary anode is copper or stainless steel with a polished surface, and / or the auxiliary anode electrode is fixed to the inner wall of the vacuum chamber, and / or the angle between the auxiliary anode electrode and the arc ion source is 90°~180°.

8. The preparation method according to claim 1, characterized in that, In step S2, the arc ion source and the auxiliary anode power supply are turned on simultaneously, with the current of the arc ion source being 40~100A and the current of the auxiliary anode power supply being 40~100A; and / or, in step S3, the arc ion source and the auxiliary anode power supply are turned on simultaneously, with the current of the arc ion source being 40~100A and the current of the auxiliary anode power supply being 40~100A.

9. The composite diamond-like coating prepared by the preparation method according to any one of claims 1 to 8 comprises a metal underlayer, a transition layer and a diamond-like coating formed on the surface of a substrate.

10. The composite diamond-like coating according to claim 9, characterized in that, The transition layer includes an amorphous carbon transition layer formed on the surface of the metal substrate and a transition diamond-like layer formed on the surface of the amorphous carbon transition layer, or a metal nitride transition layer formed on the surface of the metal substrate and a metal carbide transition layer formed on the surface of the metal nitride transition layer.

Images