A method for coating a high-hardness diamond-like carbon film

Abstract

The application relates to the technical field of diamond-like thin films, in particular to a high-hardness diamond-like thin film coating method. The high-hardness diamond-like thin film coating method comprises the following steps: polishing, cleaning, drying, heat treatment and reducing to room temperature of a metal base material; feeding into a vacuum coating device, passing in argon through an ion source, and starting ion source etching of the base material; respectively taking titanium and titanium carbide as target materials to perform sputtering deposition to form a deposition layer with a thickness of 200-400 nm; passing in a mixed gas of argon and acetylene, and adopting a bipolar pulse bias mode to form a first coating layer with a thickness of 0.5-1.5 microns; passing in a mixed gas of argon, acetylene and silane, the flow ratio of the argon, acetylene and silane being 1-2:1-2:0.1-1, and adopting a bipolar pulse bias mode to form a second coating layer with a thickness of 1-2 microns; and naturally cooling to room temperature after heat treatment under the protection of argon.

Description

Technical Field

[0001] This invention relates to the field of diamond-like carbon film technology, and more particularly to a method for coating high-hardness diamond-like carbon films. Background Technology

[0002] As modern manufacturing moves towards higher precision and reliability, the application of alloy substrates in aerospace, precision instruments, and the automotive industry faces severe challenges. Under many operating conditions, alloy materials, due to insufficient hardness and poor wear resistance, cannot meet the requirements for long-term service. Surface coating technology, by forming functional coatings, can significantly improve the wear resistance, corrosion resistance, and surface decorative properties of substrates, becoming an important technical means to solve this problem.

[0003] Diamond-like carbon (DLC) coatings, as a high-performance carbon-based thin film material, have attracted much attention due to their unique structure and performance advantages. DLC is mainly composed of carbon atoms arranged in sp... 2 sp 3 The hybrid bond structure of DLC coatings provides both excellent chemical stability and wide temperature adaptability. However, existing DLC ​​coatings still face significant bottlenecks in the synergistic optimization of hardness and tribological properties. DLC coatings prepared by traditional processes generally have a high coefficient of friction in dry environments, and as the coating thickness increases, the internal stress increases sharply, leading to a decrease in the interfacial adhesion between the coating and the substrate, resulting in problems such as peeling and flaking. At the same time, the increased surface roughness further exacerbates friction and wear.

[0004] In industrial applications, the high hardness requirement of DLC coatings is a core requirement for high-load scenarios such as cutting tools and molds. Low coefficient of friction (<0.3) and high wear resistance are key indicators for extending service life in precision transmission components. Existing technologies cannot meet these two requirements at the same time. While DLC can improve friction performance at the cost of reduced hardness, it cannot adapt to high-stress conditions.

[0005] Currently, achieving a combination of high hardness, low friction, low internal stress, and long lifespan remains a challenge restricting the large-scale industrial application of DLC technology. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for coating high-hardness diamond-like carbon thin films.

[0007] A method for coating a high-hardness diamond-like carbon film includes the following steps:

[0008] S1. Polish, clean, dry, heat treat, and cool to room temperature on the metal substrate;

[0009] S2. The substrate is fed into the vacuum coating apparatus, and argon gas is introduced through the ion source to etch the substrate. The magnetron power supply is turned on, and titanium and titanium carbide are used as targets for sputtering deposition to form a deposition layer with a thickness of 200-400nm.

[0010] During the sputtering deposition process, the target power of the titanium target is 3-4 kW and decreases at a constant rate to 0, while the target power of the titanium carbide target increases at a constant rate from 0 to 3-4 kW. The sum of the target power of the titanium target and the target power of the titanium carbide target is always 3-4 kW.

[0011] S3. A mixture of argon and acetylene is introduced, and a first coating with a thickness of 0.5-1.5 μm is formed using a bipolar pulse bias method;

[0012] S4. Introduce a mixed gas of argon, acetylene, and silane, with a flow rate ratio of argon, acetylene, and silane of 1-2:1-2:0.1-1. Form a second coating with a thickness of 1-2 μm using a bipolar pulse bias method.

[0013] S5. Heat treatment under argon protection, cool with the furnace to 100-150℃ and remove, then allow to cool naturally to room temperature.

[0014] Preferably, the specific operation of S1 is as follows: after polishing the metal substrate, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, dried, kept at 160-200℃ for 1-2 hours under vacuum, and then cooled to room temperature.

[0015] Preferably, in step S2, the vacuum in the vacuum chamber is adjusted to 1-3 × 10⁻⁶. -3 Pa.

[0016] Preferably, in S2, argon gas is introduced through an ion source to maintain the pressure of the vacuum chamber at 0.1-0.5 Pa.

[0017] Preferably, in S2, during the etching process of the substrate, the etching time is 10-20 min, the bias voltage is set to -400V to -500V, the ion source power is set to 1-1.2kW, and the system gas pressure is controlled to be 0.1-0.8Pa.

[0018] Preferably, in S2, sputtering deposition is performed using a bipolar pulse bias method, with a negative pulse voltage of -750V, a positive pulse voltage of +120 to +220V, a frequency of 2500Hz, and a duty cycle of 80%.

[0019] Preferably, in S3, the flow rate ratio of argon to acetylene is 1-2:1, maintaining the vacuum chamber pressure at 0.6-0.9 Pa.

[0020] Preferably, in S3, during the bipolar pulse bias process, the negative pulse voltage is -1000V, the positive pulse voltage is +40V, the frequency is 30KHz, and the duty cycle is 70%.

[0021] Preferably, in S4, the flow rate ratio of argon, acetylene, and silane is 1-2:1-2:0.1-1, maintaining the vacuum chamber pressure at 0.8-1 Pa.

[0022] Preferably, in S4, during the bipolar pulse bias process, the negative pulse voltage is -800V, the positive pulse voltage is +50V, the frequency is 30KHz, and the duty cycle is 70%.

[0023] Preferably, in S5, the heat treatment is specifically performed as follows: heat to 200-250℃, hold for 1-2 hours, continue to heat to 300-350℃, and hold for 10-20 minutes.

[0024] More preferably, during the process of heating to 200-250℃, the heating rate is 1-2℃ / min.

[0025] More preferably, during the process of heating to 300-350℃, the heating rate is 2-4℃ / min.

[0026] Beneficial effects:

[0027] 1. In this invention, after pretreatment of the substrate, it is first subjected to ion etching, and then titanium and titanium carbide are combined to form a transition layer with a gradual change in composition. The transition layer not only has extremely high bonding strength, but also absorbs stress through grain boundary slip, effectively reducing interfacial stress, inhibiting crack propagation, facilitating subsequent film deposition and bonding, and improving the stability of diamond-like carbon films.

[0028] 2. In this invention, a first coating is formed by a mixture of argon and acetylene, and a second coating is formed by a mixture of argon, acetylene and silane. The double-coating structure not only has high bonding strength, but also forms a Si-C bond modification layer in the outer DLC layer. This can effectively inhibit the diffusion and migration of carbon atoms caused by subsequent high-temperature treatment, and can also effectively inhibit crack propagation. It can improve friction performance while ensuring hardness, and better adapt to high-stress conditions.

[0029] 3. The invention is ingeniously designed to achieve a balance between thickness and performance through a multi-layer gradient structure. By increasing the thickness of the diamond-like carbon layer, the enormous stress caused by the high thickness of the diamond-like carbon layer can be effectively buffered, and the bonding force with the substrate can be improved, ensuring that the product has a low coefficient of friction. While ensuring application in high-load scenarios, its low coefficient of friction and high wear resistance enable it to be used stably in precision transmission components. Attached Figure Description

[0030] Figure 1 The image shows a comparison of the hardness and residual stress of the diamond-like carbon films obtained in Example 5 and Comparative Examples 1-2.

[0031] Figure 2This is a comparison chart of the friction coefficients of the diamond-like carbon films obtained in Example 5 and Comparative Examples 1-2.

[0032] Figure 3 The graph shows a comparison of the critical load for complete peeling of the diamond-like carbon film coating and the scratch crack propagation resistance of the diamond-like carbon film obtained in Example 5 and Comparative Examples 1-2. Detailed Implementation

[0033] The present invention will be further explained below with reference to specific embodiments. Example 1

[0034] A method for coating a high-hardness diamond-like carbon film includes the following steps:

[0035] S1. Using 6061 aluminum alloy obtained by T6 heat treatment as the base material, after polishing, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, dried, kept at 160℃ for 1 hour under vacuum, and then cooled to room temperature.

[0036] S2. Feed the sample into the vacuum coating apparatus and adjust the vacuum chamber vacuum to 1×10⁻⁶. -3 Pa, argon gas is introduced through the ion source to maintain the pressure of the vacuum chamber at 0.1 Pa, the ion source is turned on to etch the substrate for 10 min, the bias voltage is set to -400V, the ion source power is set to 1kW, and the system gas pressure is controlled at 0.1 Pa.

[0037] Turn on the magnetron power supply, and use titanium and titanium carbide as targets respectively to perform sputtering deposition using a bipolar pulse bias method to form a deposition layer with a thickness of 400nm.

[0038] During the sputtering deposition process, the target power of the titanium target was 3kW and decreased uniformly to 0, while the target power of the titanium carbide target increased uniformly from 0 to 3kW. The sum of the target power of the titanium target and the titanium carbide target was always 3kW. The negative pulse voltage was -750V, the positive pulse voltage was +120V, the frequency was 2500Hz, and the duty cycle was 80%.

[0039] S3. A mixture of argon and acetylene is introduced at a flow rate ratio of 1:1 to maintain a vacuum chamber pressure of 0.6 Pa. A first coating with a thickness of 1.5 μm is formed using a bipolar pulse bias method; wherein the negative pulse voltage is -1000V, the positive pulse voltage is +40V, the frequency is 30KHz, and the duty cycle is 70%.

[0040] S4. A mixture of argon, acetylene, and silane is introduced at a flow rate ratio of 1:1:0.1 to maintain a vacuum chamber pressure of 0.8 Pa. A second coating with a thickness of 2 μm is formed using a bipolar pulse bias method; wherein the negative pulse voltage is -800V, the positive pulse voltage is +50V, the frequency is 30KHz, and the duty cycle is 70%.

[0041] S5. Place it in a heat treatment apparatus, heat it to 200°C at a rate of 1°C / min under argon protection, hold it at that temperature for 1 hour, continue to heat it to 300°C at a rate of 2°C / min, hold it at that temperature for 10 minutes, cool it down to 100°C with the furnace, and take it out to cool naturally to room temperature. Example 2

[0042] A method for coating a high-hardness diamond-like carbon film includes the following steps:

[0043] S1. Using 6061 aluminum alloy obtained by T6 heat treatment as the base material, after polishing, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, dried, kept at 200℃ for 2 hours under vacuum, and then cooled to room temperature.

[0044] S2. The sample is fed into the vacuum coating apparatus, and the vacuum chamber is adjusted to 3×10⁻⁶. -3 Pa, argon gas is introduced through the ion source to maintain the pressure of the vacuum chamber at 0.5 Pa, the ion source is turned on to etch the substrate for 20 min, the bias voltage is set to -500V, the ion source power is set to 1.2kW, and the system gas pressure is controlled at 0.8 Pa;

[0045] Turn on the magnetron power supply, and use titanium and titanium carbide as targets respectively to perform sputtering deposition using a bipolar pulse bias method to form a deposition layer with a thickness of 200nm.

[0046] During the sputtering deposition process, the target power of the titanium target was 4kW and decreased uniformly to 0, while the target power of the titanium carbide target increased uniformly from 0 to 4kW. The sum of the target power of the titanium target and the titanium carbide target was always 4kW. The negative pulse voltage was -750V, the positive pulse voltage was +220V, the frequency was 2500Hz, and the duty cycle was 80%.

[0047] S3. A mixture of argon and acetylene is introduced at a flow rate ratio of 2:1 to maintain a vacuum chamber pressure of 0.9 Pa. A first coating with a thickness of 0.7 μm is formed using a bipolar pulse bias method; wherein the negative pulse voltage is -1000V, the positive pulse voltage is +40V, the frequency is 30KHz, and the duty cycle is 70%.

[0048] S4. A mixture of argon, acetylene, and silane is introduced at a flow rate ratio of 2:2:1 to maintain a vacuum chamber pressure of 1 Pa. A second coating with a thickness of 1.2 μm is formed using a bipolar pulse bias method; the negative pulse voltage is -800V, the positive pulse voltage is +50V, the frequency is 30KHz, and the duty cycle is 70%.

[0049] S5. Place it in a heat treatment apparatus, heat it to 250°C at a rate of 2°C / min under argon protection, hold it at that temperature for 2 hours, continue to heat it to 350°C at a rate of 4°C / min, hold it at that temperature for 20 minutes, cool it down to 150°C with the furnace, and take it out to cool naturally to room temperature. Example 3

[0050] A method for coating a high-hardness diamond-like carbon film includes the following steps:

[0051] S1. Using 6061 aluminum alloy obtained by T6 heat treatment as the base material, after polishing, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, dried, kept at 170℃ for 100 minutes under vacuum, and then cooled to room temperature.

[0052] S2. Feed the sample into the vacuum coating apparatus and adjust the vacuum chamber vacuum to 1.5 × 10⁻⁶. -3 Pa, argon gas was introduced through the ion source to maintain the pressure of the vacuum chamber at 0.4 Pa, the ion source was turned on to etch the substrate for 12 min, the bias voltage was set to -480V, the ion source power was set to 1.05kW, and the system gas pressure was controlled at 0.6 Pa.

[0053] With the magnetron power supply turned on, titanium and titanium carbide were used as targets, and sputtering deposition was performed using a bipolar pulse bias method to form a deposition layer with a thickness of 350 nm.

[0054] During the sputtering deposition process, the target power of the titanium target was 3.2 kW and decreased uniformly to 0, while the target power of the titanium carbide target increased uniformly from 0 to 3.2 kW. The sum of the target power of the titanium target and the titanium carbide target remained at 3.2 kW. The negative pulse voltage was -750 V, the positive pulse voltage was +140 V, the frequency was 2500 Hz, and the duty cycle was 80%.

[0055] S3. A mixture of argon and acetylene is introduced at a flow rate ratio of 1.8:1 to maintain a vacuum chamber pressure of 0.7 Pa. A first coating with a thickness of 1.2 μm is formed using a bipolar pulse bias method; wherein the negative pulse voltage is -1000V, the positive pulse voltage is +40V, the frequency is 30KHz, and the duty cycle is 70%.

[0056] S4. A mixture of argon, acetylene, and silane is introduced at a flow rate ratio of 1.8:1.2:0.7 to maintain a vacuum chamber pressure of 0.85 Pa. A second coating with a thickness of 1.8 μm is formed using a bipolar pulse bias method; the negative pulse voltage is -800 V, the positive pulse voltage is +50 V, the frequency is 30 kHz, and the duty cycle is 70%.

[0057] S5. Place it in a heat treatment apparatus, and under argon protection, heat it to 210°C at a rate of 1.8°C / min, hold it for 100 min, and continue to heat it to 340°C at a rate of 2.5°C / min, hold it for 12 min, cool it with the furnace to 130°C, and take it out to cool naturally to room temperature. Example 4

[0058] A method for coating a high-hardness diamond-like carbon film includes the following steps:

[0059] S1. Using 6061 aluminum alloy obtained by T6 heat treatment as the base material, after polishing, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, dried, kept at 190℃ for 80 minutes under vacuum, and then cooled to room temperature.

[0060] S2. Feed the sample into the vacuum coating apparatus and adjust the vacuum chamber vacuum to 2.5 × 10⁻⁶. -3 Pa, argon gas is introduced through the ion source to maintain the pressure of the vacuum chamber at 0.2 Pa, the ion source is turned on to etch the substrate for 18 min, the bias voltage is set to -420V, the ion source power is set to 1.15kW, and the system gas pressure is controlled at 0.2 Pa.

[0061] With the magnetron power supply turned on, titanium and titanium carbide were used as targets, and sputtering deposition was performed using a bipolar pulse bias method to form a deposition layer with a thickness of 250 nm.

[0062] During the sputtering deposition process, the target power of the titanium target was 3.8 kW and decreased uniformly to 0, while the target power of the titanium carbide target increased uniformly from 0 to 3.8 kW. The sum of the target power of the titanium target and the titanium carbide target was always 3.8 kW. The negative pulse voltage was -750 V, the positive pulse voltage was +200 V, the frequency was 2500 Hz, and the duty cycle was 80%.

[0063] S3. A mixture of argon and acetylene is introduced at a flow rate ratio of 1.2:1 to maintain a vacuum chamber pressure of 0.8 Pa. A first coating with a thickness of 0.8 μm is formed using a bipolar pulse bias method; wherein the negative pulse voltage is -1000V, the positive pulse voltage is +40V, the frequency is 30KHz, and the duty cycle is 70%.

[0064] S4. A mixture of argon, acetylene, and silane is introduced at a flow rate ratio of 1.2:1.8:0.3 to maintain a vacuum chamber pressure of 0.95 Pa. A second coating with a thickness of 1.2 μm is formed using a bipolar pulse bias method; the negative pulse voltage is -800 V, the positive pulse voltage is +50 V, the frequency is 30 kHz, and the duty cycle is 70%.

[0065] S5. Place it in a heat treatment apparatus, heat it to 230°C at a rate of 1.2°C / min under argon protection, hold it at that temperature for 80 min, continue heating it to 320°C at a rate of 3.5°C / min, hold it at that temperature for 18 min, cool it to 110°C with the furnace and take it out, then let it cool naturally to room temperature. Example 5

[0066] A method for coating a high-hardness diamond-like carbon film includes the following steps:

[0067] S1. Using 6061 aluminum alloy obtained by T6 heat treatment as the base material, after polishing, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, dried, kept at 180℃ for 90 minutes under vacuum, and then cooled to room temperature.

[0068] S2. Feed the sample into the vacuum coating apparatus and adjust the vacuum chamber vacuum to 2×10⁻⁶. -3 Pa, argon gas is introduced through the ion source to maintain the pressure of the vacuum chamber at 0.3 Pa, the ion source is turned on to etch the substrate for 15 min, the bias voltage is set to -450V, the ion source power is set to 1.1kW, and the system gas pressure is controlled at 0.4 Pa.

[0069] Turn on the magnetron power supply, and use titanium and titanium carbide as targets respectively to perform sputtering deposition using a bipolar pulse bias method to form a deposition layer with a thickness of 300nm;

[0070] During the sputtering deposition process, the target power of the titanium target was 3.5 kW and decreased uniformly to 0, while the target power of the titanium carbide target increased uniformly from 0 to 3.5 kW. The sum of the target power of the titanium target and the titanium carbide target was always 3.5 kW. The negative pulse voltage was -750 V, the positive pulse voltage was +170 V, the frequency was 2500 Hz, and the duty cycle was 80%.

[0071] S3. A mixture of argon and acetylene is introduced at a flow rate ratio of 1.5:1 to maintain a vacuum chamber pressure of 0.75 Pa. A first coating with a thickness of 1 μm is formed using a bipolar pulse bias method; wherein the negative pulse voltage is -1000V, the positive pulse voltage is +40V, the frequency is 30KHz, and the duty cycle is 70%.

[0072] S4. A mixture of argon, acetylene, and silane is introduced at a flow rate ratio of 3:3:1 to maintain a vacuum chamber pressure of 0.9 Pa. A second coating with a thickness of 1.5 μm is formed using a bipolar pulse bias method; the negative pulse voltage is -800 V, the positive pulse voltage is +50 V, the frequency is 30 kHz, and the duty cycle is 70%.

[0073] S5. Place it in a heat treatment apparatus, heat it to 220°C at a rate of 1.5°C / min under argon protection, hold it at that temperature for 90 min, continue to heat it to 330°C at a rate of 3°C / min, hold it at that temperature for 15 min, cool it to 120°C with the furnace and take it out, then let it cool naturally to room temperature.

[0074] Comparative Example 1

[0075] A method for coating a high-hardness diamond-like carbon film includes the following steps:

[0076] S1. Using 6061 aluminum alloy obtained by T6 heat treatment as the base material, after polishing, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, dried, kept at 180℃ for 90 minutes under vacuum, and then cooled to room temperature.

[0077] S2. Feed the sample into the vacuum coating apparatus and adjust the vacuum chamber vacuum to 2×10⁻⁶. -3 Pa, argon gas is introduced through the ion source to maintain the pressure of the vacuum chamber at 0.3 Pa, the ion source is turned on to etch the substrate for 15 min, the bias voltage is set to -450V, the ion source power is set to 1.1kW, and the system gas pressure is controlled at 0.4 Pa.

[0078] Turn on the magnetron power supply, use titanium as the target material, and sputter to deposit a first layer with a thickness of 150 nm using a bipolar pulse bias method; continue to use titanium carbide as the target material and sputter to deposit a second layer with a thickness of 150 nm using a bipolar pulse bias method.

[0079] During the sputtering deposition process, the target power for both titanium and titanium carbide targets was 3.5kW; the negative pulse voltage was -750V, the positive pulse voltage was +170V, the frequency was 2500Hz, and the duty cycle was 80%.

[0080] S3. A mixture of argon and acetylene is introduced at a flow rate ratio of 1.5:1 to maintain a vacuum chamber pressure of 0.75 Pa. A first coating with a thickness of 1 μm is formed using a bipolar pulse bias method; wherein the negative pulse voltage is -1000V, the positive pulse voltage is +40V, the frequency is 30KHz, and the duty cycle is 70%.

[0081] S4. A mixture of argon, acetylene, and silane is introduced at a flow rate ratio of 3:3:1 to maintain a vacuum chamber pressure of 0.9 Pa. A second coating with a thickness of 1.5 μm is formed using a bipolar pulse bias method; the negative pulse voltage is -800 V, the positive pulse voltage is +50 V, the frequency is 30 kHz, and the duty cycle is 70%.

[0082] S5. Place it in a heat treatment apparatus, heat it to 220°C at a rate of 1.5°C / min under argon protection, hold it at that temperature for 90 min, continue to heat it to 330°C at a rate of 3°C / min, hold it at that temperature for 15 min, cool it to 120°C with the furnace and take it out, then let it cool naturally to room temperature.

[0083] Comparative Example 2

[0084] A method for coating a high-hardness diamond-like carbon film includes the following steps:

[0085] S1. Using 6061 aluminum alloy obtained by T6 heat treatment as the base material, after polishing, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, dried, kept at 180℃ for 90 minutes under vacuum, and then cooled to room temperature.

[0086] S2. Feed the sample into the vacuum coating apparatus and adjust the vacuum chamber vacuum to 2×10⁻⁶. -3 Pa, argon gas is introduced through the ion source to maintain the pressure of the vacuum chamber at 0.3 Pa, the ion source is turned on to etch the substrate for 15 min, the bias voltage is set to -450V, the ion source power is set to 1.1kW, and the system gas pressure is controlled at 0.4 Pa.

[0087] Turn on the magnetron power supply, and use titanium and titanium carbide as targets respectively to perform sputtering deposition using a bipolar pulse bias method to form a deposition layer with a thickness of 300nm;

[0088] During the sputtering deposition process, the target power of the titanium target was 3.5 kW and decreased uniformly to 0, while the target power of the titanium carbide target increased uniformly from 0 to 3.5 kW. The sum of the target power of the titanium target and the titanium carbide target was always 3.5 kW. The negative pulse voltage was -750 V, the positive pulse voltage was +170 V, the frequency was 2500 Hz, and the duty cycle was 80%.

[0089] S3. A mixture of argon and acetylene is introduced at a flow rate ratio of 1.5:1 to maintain a vacuum chamber pressure of 0.75 Pa. A 2.5 μm thick coating is formed using a bipolar pulse bias method; the negative pulse voltage is -1000 V, the positive pulse voltage is +40 V, the frequency is 30 kHz, and the duty cycle is 70%.

[0090] S4. Place it in a heat treatment apparatus, heat it to 220°C at a rate of 1.5°C / min under argon protection, hold it at that temperature for 90 min, continue to heat it to 330°C at a rate of 3°C / min, hold it at that temperature for 15 min, cool it to 120°C with the furnace, and take it out to cool naturally to room temperature.

[0091] The hardness of the diamond-like carbon films obtained in Example 5 and Comparative Examples 1-2 was measured using a nanoindenter; and the residual stress of each group of diamond-like carbon films was measured using a residual stress meter. A laser emitter and a PDS detector were used, and the residual stress value of the film was measured and calculated by moving the sample to change the laser reflection angle. The stress test range was 0.001-100 GPa, and the resolution was 0.001 GPa.

[0092] like Figure 1 As shown, the diamond-like carbon film obtained in Example 5 has the highest hardness and the lowest residual stress, which is better than Comparative Examples 1-2 (P<0.05).

[0093] The coefficient of friction of the diamond-like carbon films obtained in Example 5 and Comparative Examples 1-2 was determined using an HSR-2M coating tribometer. Figure 2As shown, the coefficient of friction of the diamond-like carbon film obtained in Example 5 and Comparative Example 1 was significantly lower than that in Comparative Example 2 (P < 0.01), but there was no significant difference between Example 5 and Comparative Example 1 (P > 0.05).

[0094] The frictional properties of the diamond-like carbon films obtained in Example 5 and Comparative Examples 1-2 were measured using a multi-functional high-temperature friction and wear testing machine. A certain normal load was applied to the grinding pair, causing it to reciprocate on the sample surface. By observing the scratch trajectory under a microscope, it was found that during the sliding of the indenter, edge cracks, conformal cracks, local peeling, and complete peeling appeared sequentially on the surface of each group of diamond-like carbon films.

[0095] The critical load for the appearance of microcracks in the diamond-like carbon (DLC) film is defined as Lc1, the critical load for the coating to begin peeling is defined as Lc2, and the critical load for the coating to completely peel off is defined as Lc3. This application uses Lc3 to characterize the adhesion of the DLC film, while the toughness of the coating is characterized by scratch crack propagation resistance (CPRs).

[0096] CPRs = Lc1 × (Lc2 – Lc1)

[0097] like Figure 3 As shown, the diamond-like carbon film obtained in Example 5 has the highest bonding strength and scratch crack propagation resistance, which is better than Comparative Examples 1-2 (P<0.05).

[0098] The reason for the above results is that, after pretreatment of the substrate, the present invention first performs ion etching, and then uses a titanium and titanium carbide composite to form a transition layer with a gradual change in composition. The transition layer not only has extremely high bonding strength, but also absorbs stress through grain boundary slip, effectively reducing interfacial stress, inhibiting crack propagation, facilitating subsequent film deposition and bonding, and improving the stability of diamond-like carbon films. Then, the present invention first uses a mixture of argon and acetylene to form a first coating, and then uses a mixture of argon, acetylene, and silane to form a second coating. The double-coating structure not only has high bonding strength, but the outer DLC forms a Si-C bond modification layer, which can effectively inhibit the diffusion and migration of carbon atoms caused by subsequent high-temperature treatment, and also effectively inhibit crack propagation. It can improve friction performance while ensuring hardness, and better adapt to high-stress conditions.

[0099] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for coating a high-hardness diamond-like carbon film, characterized in that, Includes the following steps: S1. Polish, clean, dry, heat treat, and cool to room temperature on the metal substrate; S2. The substrate is fed into the vacuum coating apparatus, and argon gas is introduced through the ion source to etch the substrate. The magnetron power supply is turned on, and titanium and titanium carbide are used as targets for sputtering deposition to form a deposition layer with a thickness of 200-400nm. During the etching process, the etching time is 10-20 min, the bias voltage is set to -400V to -500V, the ion source power is set to 1-1.2kW, and the system gas pressure is controlled to be 0.1-0.8Pa. During the sputtering deposition process, the target power of the titanium target is 3-4 kW and decreases at a constant rate to 0, while the target power of the titanium carbide target increases at a constant rate from 0 to 3-4 kW. The sum of the target power of the titanium target and the target power of the titanium carbide target is always 3-4 kW. S3. A mixture of argon and acetylene is introduced, and a first coating with a thickness of 0.5-1.5 μm is formed using a bipolar pulse bias method; S4. Introduce a mixed gas of argon, acetylene, and silane, with a flow rate ratio of argon, acetylene, and silane of 1-2:1-2:0.1-1. Form a second coating with a thickness of 1-2 μm using a bipolar pulse bias method. S5. Heat treatment under argon protection, cool with the furnace to 100-150℃ and remove, then allow to cool naturally to room temperature.

2. The high-hardness diamond-like carbon thin film coating method according to claim 1, characterized in that, The specific operation of S1 is as follows: After polishing the metal substrate, it is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, dried, kept at 160-200℃ for 1-2 hours under vacuum, and then cooled to room temperature.

3. The high-hardness diamond-like carbon thin film coating method according to claim 1, characterized in that, In S2, the vacuum in the vacuum chamber is adjusted to 1-3×10⁻⁶. -3 Pa.

4. The high-hardness diamond-like carbon thin film coating method according to claim 1, characterized in that, In S2, argon gas is introduced through an ion source to maintain the pressure in the vacuum chamber at 0.1-0.5 Pa.

5. The high-hardness diamond-like carbon thin film coating method according to claim 1, characterized in that, In S2, sputtering deposition is performed using a bipolar pulse bias method, with a negative pulse voltage of -750V, a positive pulse voltage of +120 to +220V, a frequency of 2500Hz, and a duty cycle of 80%.

6. The high-hardness diamond-like carbon thin film coating method according to claim 1, characterized in that, In S3, the flow ratio of argon to acetylene is 1-2:1, maintaining the vacuum chamber pressure at 0.6-0.9 Pa. In S3, during the bipolar pulse bias process, the negative pulse voltage is -1000V, the positive pulse voltage is +40V, the frequency is 30KHz, and the duty cycle is 70%.

7. The high-hardness diamond-like carbon thin film coating method according to claim 1, characterized in that, In S4, the flow rate ratio of argon, acetylene, and silane is 1-2:1-2:0.1-1, maintaining the vacuum chamber pressure at 0.8-1 Pa. In S4, during the bipolar pulse bias process, the negative pulse voltage is -800V, the positive pulse voltage is +50V, the frequency is 30KHz, and the duty cycle is 70%.

8. The high-hardness diamond-like carbon thin film coating method according to claim 1, characterized in that, In S5, the specific heat treatment operation is as follows: heat up to 200-250℃, hold for 1-2 hours, continue to heat up to 300-350℃, and hold for 10-20 minutes.

9. The high-hardness diamond-like carbon thin film coating method according to claim 8, characterized in that, During the process of heating to 200-250℃, the heating rate is 1-2℃ / min; during the process of heating to 300-350℃, the heating rate is 2-4℃ / min.

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