Process method for depositing DLC coating in pipe

Abstract

The invention relates to a process method for depositing a DLC (diamond-like carbon) coating in a pipe, belongs to the technical field of PECVD (plasma enhanced chemical vapor deposition) carbide film preparation, and adopts high-voltage pulse enhancement. The DLC is deposited through the hollow cathode effect, the economic loss and safety problems caused by corrosion and local scratch in the pipeline are solved due to the characteristics of low friction, high hardness, wear resistance and corrosion resistance of the DLC, the hardness of the coating reaches up to 15-20 GPa, the friction coefficient is as low as 0.017, and meanwhile, the coating has very high binding force due to the design that multiple layers of soft and hard coatings are alternately arranged. Meanwhile, the coating can also be applied to coating of deep holes in parts, such as internal splines and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of PECVD carbide thin film preparation, and particularly relates to a process method for depositing DLC coatings inside a tube. Background Art

[0002] As a coating with excellent properties, diamond-like carbon (DLC) thin films are widely used in industry due to their high hardness, low friction coefficient, good biocompatibility, chemical inertness, and low electrical conductivity. DLC thin films are a new type of carbon material that combines the excellent properties of diamond and graphene and are widely used in many fields. DLC thin films have many excellent properties, such as high hardness, good corrosion resistance, high thermal conductivity, high optical transmittance, high resistivity, good wear resistance, low friction coefficient, and good biocompatibility. DLC thin films are widely used in many fields such as machinery, electronics, medicine, and aerospace. The applications in these fields are of great significance for the sustainable development of society. Depositing DLC inside pipes or metal parts is a deposition technology developed in recent years. Conventional pipes on the market are mostly made of stainless steel or alloy steel pipes, and the protection effect of pipes under various harsh conditions such as strong corrosion is not satisfactory, such as in natural gas pipelines, oil pipelines, or deep-sea applications. Summary of the Invention

[0003] In view of the above problems existing in the prior art, the main object of the present invention is to provide a process method for depositing DLC coatings inside a tube.

[0004] The technical solution of the present invention is as follows: A process method for depositing DLC coatings inside a tube, designing an anode, an anode device that integrates water cooling and gas inlet, including the following steps: Fix the pipe in the chamber and rotate it. Connect the negative pole of the power supply to the pipe, and the positive pole is a stainless steel pipe, which also has internal water cooling. There are openings on both sides of the steel pipe for introducing carbon-containing gases. The chamber is evacuated. After evacuating to 5.0E-3 Pa, introduce Ar at 100-500 sccm. When the vacuum degree reaches 0.8-5 Pa, turn on the power supply to ionize Ar, with a voltage of 1000 V-4000 V, a frequency of 50 Hz-5000 Hz, and a pulse width of 50 us-1000 us.

[0005] After cleaning and activation, turn off Ar and introduce silane (tetramethylsilane) with a flow rate of 100-500 sccm at a vacuum degree of 0.5-7 Pa for depositing the bottom layer. The silane is ionized into silicon ions and deposits a layer of silicon with a thickness of 1-3 um on the inner wall of the pipe under the action of a negative bias voltage. The power supply voltage is 1000 V-4000 V, the frequency is 50 Hz-5000 Hz, the pulse width is 50 us-1000 us, and the time is 30-180 minutes.

[0006] After depositing the silicon bottom layer, a transition layer is deposited to achieve a slow transition between the silicon material and the carbon material, reducing the problem of excessive internal stress caused by material mismatch and inconsistent thermal expansion coefficients. The transition layer is formed by first using more silane and less C2H2, and then reducing the silane by 10 minutes while increasing C2H2 at the same time; specifically, the ratio of silane to C2H2 is 10:1 (for 10 minutes); 7:3 (for 10 minutes); 4:6 (for 10 minutes); 1:9 (for 20 minutes), the vacuum degree is 1pa - 7pa, the voltage is 2000V - 5000V, the frequency is 100Hz - 2000Hz, the pulse width is 50us - 3000us, and the thickness of the transition layer is 500nm - 2um.

[0007] For the DLC layer, turn off the silane and introduce C2H2 to assist in the ionization deposition of the DLC layer through the carbon source and Ar. After C2H2 is ionized into carbon ions, it reaches the inner wall with high energy under the influence of the negative voltage on the inner wall of the pipeline and forms sp3 bonds (sp2 bonds are graphite, and sp3 bonds are diamond). The power supply voltage is 3000V - 7000V, the frequency is 30Hz - 5000Hz, the pulse width is 50us - 5000us, the vacuum degree is 1.5pa - 9pa, and the deposition time is 30 minutes - 500 minutes.

[0008] Compared with the prior art, the advantages and positive effects of the present invention are as follows: In the present invention, through the hollow cathode effect, a DLC (diamond-like carbon) coating with high hardness, self-lubrication, and corrosion resistance is deposited inside the pipeline.

[0009] In the present invention, high-voltage discharge is generated inside the pipeline through the hollow cathode effect, so that the carbon ions generated by the ionization of the carbon-containing gas reach the inner wall of the pipeline with high energy under the action of a suitable pulsed negative bias voltage and are deposited on the inner wall surface to form a DLC (diamond-like carbon coating). BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is an overall view of a process method for depositing a DLC coating inside a pipeline provided by the present invention; Figure 2 It is a cross-sectional view of a pipeline of a process method for depositing a DLC coating inside a pipeline provided by the present invention; Figure 3 It is a single-cycle layer diagram of a process method for depositing a DLC coating inside a pipeline provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0012] Referring to Figures 1-3 , a process method for depositing a DLC coating in a pipe, designing an anode, an anode device integrating water cooling and air intake, including the following steps: Fix the pipe in the chamber and rotate it. Connect the negative electrode of the power supply to the pipe, and the positive electrode is a stainless steel pipe, which has water cooling inside. There are holes on both sides of the steel pipe for introducing carbon-containing gases. The chamber is evacuated. After pumping to 5.0E-3 Pa, introduce Ar at 100-500 sccm. When the vacuum degree reaches 0.8-5 Pa, turn on the power supply to ionize Ar, with a voltage of 1000V-4000V, a frequency of 50Hz-5000Hz, and a pulse width of 50us-1000us.

[0013] After cleaning and activation, close Ar and introduce silane (tetramethylsilane) with a flow rate of 100-500 sccm and a vacuum degree of 0.5-7 Pa for depositing the bottom layer. The silane is ionized into silicon ions and deposits a layer of silicon with a thickness of 1-3 um on the inner wall of the pipe under the action of a negative bias voltage. The power supply voltage is 1000V-4000V, the frequency is 50Hz-5000Hz, the pulse width is 50us-1000us, and the time is 30-180 minutes.

[0014] After depositing the silicon bottom layer, deposit a transition layer to achieve a slow transition between the silicon material and the carbon material, reducing the problem of excessive internal stress caused by material mismatch and inconsistent thermal expansion coefficients. The transition layer is formed by first using more silane and less C2H2, and then reducing the silane by 10 minutes each time while increasing C2H2 at the same time. Specifically, the ratio of silane:C2H2 is 10:1 (for 10 minutes); 7:3 (for 10 minutes); 4:6 (for 10 minutes); 1:9 (for 20 minutes), with a vacuum degree of 1Pa-7Pa, a voltage of 2000V-5000V, a frequency of 100Hz-2000Hz, a pulse width of 50us-3000us, and the thickness of the transition layer is 500nm-2um.

[0015] For the DLC layer, close the silane and introduce C2H2 to assist in the ionization deposition of the DLC layer through the carbon source and Ar. After the C2H2 is ionized into carbon ions, it reaches the inner wall with high energy under the influence of the negative voltage on the inner wall of the pipe and forms sp3 bonds (sp2 bonds are graphite, and sp3 bonds are diamond). The power supply voltage is 3000V-7000V, the frequency is 30Hz -5000Hz, the pulse width is 50us-5000us, the vacuum degree is 1.5Pa-9Pa, and the deposition time is 30 minutes-500 minutes.

[0016] Specifically, the material of the device is stainless steel, and water can be passed through for cooling during hollow cathode discharge, avoiding the phenomenon of excessive temperature caused by the anode absorbing hot electrons during discharge, and at the same time having an air intake function.

[0017] Specifically, a hollow cathode effect is formed in the pipeline through high-voltage discharge. The gas is broken down and ionized into high-energy ions. At the same time, due to the high-voltage negative charge on the inner wall of the pipeline, the positively charged ions clean the inner wall of the pipeline under the action of the negative bias voltage, and the activation time is 10 - 50 minutes.

[0018] Specifically, silane is introduced through the anode and ionized inside the pipeline, and a layer of silicon with a thickness of 500 nm - 3 μm is deposited on the inner wall of the pipeline as the bottom layer. The voltage is 1500 v - 4000 v, the frequency is 50 HZ - 5000 HZ, the pulse width is 50 μm - 5000 μm, the duty cycle is 1% - 40%, and the air pressure is 2 pa - 10 pa.

[0019] Specifically, after the silicon layer, silane and acetylene are introduced and the ratio of silane to acetylene is adjusted to deposit a transition Si - SiCx - SiC layer with a thickness of 300 nm - 1 μm, the air pressure is 2 - 8 pa, the voltage is 2500 - 5000 V, and the duty cycle is 1% - 20%.

[0020] Specifically, a certain proportion of argon and acetylene are introduced to deposit a DLC (diamond - like carbon) coating. The air pressure is 2 - 10 pa, the voltage is 3000 - 7000 v, the frequency is 50 HZ - 5000 HZ, the pulse width is 50 μm - 5000 μm, the duty cycle is 1% - 20%, and the thickness is 1 - 3 μm.

[0021] Specifically, through multiple cyclic layers, the internal stress is reduced and the bonding strength is improved. The above Si - SiCx - SiC - DLC is taken as one cycle, and a high - protection composite DLC coating with a total thickness of 30 - 50 μm is prepared through 4 - 5 cycles.

[0022] Specifically, during the deposition process, the pipeline to be plated is fixed and rotated.

[0023] Specifically, the anode air intake holes are arranged at a certain distance and distributed along the entire length of the pipeline to be plated.

[0024] Working principle: In the first step, after polishing the inside and outside of the pipeline, it is placed in ethanol and ultrasonically cleaned for 20 minutes, then put into the equipment to evacuate to 5.0E-3 Pa and heated to 100 °C; in the second step, plasma glow cleaning is carried out. Ar is introduced to make the vacuum degree reach 5.0E0 Pa, and the high-voltage pulse power supply is turned on with a voltage of 3000 V, a frequency of 200 Hz, and a pulse width of 100 us to perform plasma cleaning and etching on the inside of the pipeline for 40 minutes; in the third step, a mixed gas of Ar and silane with a ratio of 95:5 is introduced. The high-voltage power supply is turned on at a vacuum degree of 4.0E0 Pa, with a voltage of 2500 V, a frequency of 500 Hz, and a pulse width of 100 us to deposit a silicon layer on the inside of the pipeline for 50 minutes; in the fourth step, silane and acetylene are introduced with a ratio of 10:1, a voltage of 4000 V, a frequency of 100 Hz, and a pulse width of 100 us to deposit a transition layer with a deposition time of 10 minutes; in the fifth step, silane and acetylene are introduced with a ratio of 7:3, a voltage of 4000 V, a frequency of 100 Hz, and a pulse width of 100 us to deposit a transition layer with a deposition time of 10 minutes; in the sixth step, silane and acetylene are introduced with a ratio of 4:6, a voltage of 4000 V, a frequency of 100 Hz, and a pulse width of 100 us to deposit a transition layer with a deposition time of 10 minutes; in the seventh step, silane and acetylene are introduced with a ratio of 1:9, a voltage of 4000 V, a frequency of 100 Hz, and a pulse width of 100 us to deposit a transition layer with a deposition time of 10 minutes; in the eighth step, to deposit a DLC layer, Ar and C2H2 are introduced with a ratio of 4:6, a vacuum degree of 4.5 Pa, the high-voltage power supply is turned on with a voltage of 5000 v, a frequency of 100 Hz, and a pulse width of 100 us, and the deposition time is 120 minutes. Then, the above steps three to eight are a cycle layer, and repeating five cycles can obtain a DLC coating with high thickness, corrosion resistance, low friction coefficient, and high hardness.

[0025] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, terms such as "installation", "equipped with", "connection", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0026] The above are only the preferred embodiments of the present application and are not used to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A process for depositing a DLC coating inside a pipe, including designing an anode which integrates water cooling and gas inlet, characterized by the following steps: Fix the pipe in the chamber and rotate it. Connect the negative electrode of the power supply to the pipe, and the positive electrode is a stainless steel pipe with internal water cooling. Open holes on both sides of the pipe for introducing carbon-containing gases. Evacuate the chamber. After evacuating to 5.0E-3 Pa, introduce Ar at 100-500 sccm. When the vacuum degree reaches 0.8-5 Pa, turn on the power supply to ionize Ar, with a voltage of 1000V-4000V, a frequency of 50Hz-5000Hz, and a pulse width of 50us-1000us. After cleaning and activation, close the Ar and introduce silane (tetramethylsilane) with a flow rate of 100-500 sccm at a vacuum degree of 0.5-7 Pa for depositing the bottom layer. The silane is ionized into silicon ions and deposits a layer of silicon with a thickness of 1-3um on the inner wall of the pipe under the action of a negative bias voltage. The power supply voltage is 1000V-4000V, the frequency is 50Hz-5000Hz, the pulse width is 50us-1000us, and the time is 30-180 minutes. After depositing the silicon bottom layer, deposit a transition layer to achieve a slow transition between silicon materials and carbon materials, reducing the problem of excessive internal stress caused by material mismatch and inconsistent thermal expansion coefficients. The transition layer is formed by first using more silane and less C2H2, and then reducing the silane by 10 minutes while increasing C2H2 at the same time. The specific ratio of silane:C2H2 is 10:1 (10 minutes); 7:3 (10 minutes); 4:6 (10 minutes); 1:9 (20 minutes), with a vacuum degree of 1Pa-7Pa, a voltage of 2000V-5000V, a frequency of 100Hz-2000Hz, a pulse width of 50us-3000us, and a transition layer thickness of 500nm-2um. For the DLC layer, close the silane and introduce C2H2 to assist in the ionization deposition of the DLC layer through the carbon source and Ar. After the C2H2 is ionized into carbon ions, it reaches the inner wall with high energy under the influence of the negative voltage on the inner wall of the pipe and forms sp3 bonds (sp2 bonds are graphite, and sp3 bonds are diamond). The power supply voltage is 3000V-7000V, the frequency is 30Hz -5000Hz, the pulse width is 50us-5000us, the vacuum degree is 1.5Pa-9Pa, and the deposition time is 30 minutes-500 minutes.

2. The process method for depositing DLC coating in a tube according to claim 1, characterized in that: The material of the device is stainless steel.

3. A process for depositing a DLC coating in a tube according to claim 1, characterized in that: In the first step, a hollow cathode effect is formed inside the pipe through high-voltage discharge. The gas is broken down and ionized into high-energy ions. At the same time, due to the high-voltage negative charge on the inner wall of the pipe, the positively charged ions clean the inner wall of the pipe under the action of the negative bias voltage, and the activation time is 10-50 minutes.

4. A process for depositing a DLC coating in a tube according to claim 1, characterized in that: In the second step, introduce silane through the anode and ionize it inside the pipe to deposit a layer of silicon with a thickness of 500nm-3um on the inner wall of the pipe as the bottom layer, with a voltage of 1500v-4000v, a frequency of 50HZ-5000HZ, a pulse width of 50um-5000um, a duty cycle of 1%-40%, and a gas pressure of 2pa-10pa.

5. A process for depositing a DLC coating in a tube according to claim 1, characterized in that: In the third step, silane and acetylene are introduced after the silicon layer, and the ratio of silane to acetylene is adjusted to deposit a transition Si-SiCx-SiC layer with a thickness of 300 nm - 1 μm, a gas pressure of 2 - 8 Pa, a voltage of 2500 - 5000 V, and a duty cycle of 1% - 20%.

6. A process for depositing a DLC coating in a tube according to claim 1, characterized in that: In the fourth step, a certain proportion of argon and acetylene are introduced to deposit a DLC (diamond-like carbon) coating with a gas pressure of 2 - 10 Pa, a voltage of 3000 - 7000 V, a frequency of 50 Hz - 5000 Hz, a pulse width of 50 μm - 5000 μm, a duty cycle of 1% - 20%, and a thickness of 1 - 3 μm.

7. A process for depositing a DLC coating in a tube according to claim 1, characterized in that: By means of multiple cycle layers, the internal stress is reduced and the bonding force is improved. The above Si-SiCx-SiC-DLC is one cycle, and a high-protection composite DLC coating with a total thickness of 30 - 50 μm is prepared through 4 - 5 cycles.

8. A process for depositing a DLC coating in a tube according to claim 1, characterized in that: During the deposition process, the pipe to be plated is fixed and rotated.

9. A process for depositing a DLC coating in a tube according to claim 1, characterized in that: The anode air inlet holes are arranged at a certain distance and distributed along the entire length of the pipe to be plated.

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