A high-density, highly insulating ultra-thick carbon-doped ceramic coating and its preparation method

Abstract

This invention provides a highly dense and strongly insulating ultra-thick carbon-doped ceramic coating and its preparation method, comprising the following steps: S1, substrate pretreatment: the pretreatment includes polishing and chemical cleaning sequentially; S2, plasma sputtering cleaning; S3, deposition of an underlayer; the underlayer is a Ti / TiC underlayer or a Cr / CrN underlayer; the thickness of the underlayer is 0.2-0.8 μm; S4, deposition of a carbon-based intermediate layer on the underlayer; the thickness of the carbon-based intermediate layer is 2-10 μm; S5, deposition of a C / SiO2 / Al2O3 ceramic surface layer on the carbon-based intermediate layer; the thickness of the C / SiO2 / Al2O3 ceramic surface layer is 10-50 μm. The total thickness of the coating prepared by this invention can reach 45-60 μm, and it also achieves high density, high insulation, high adhesion, and high wear resistance; moreover, the preparation method is simple, requiring only the deposition of three layers on the substrate to obtain the ceramic coating.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, and more specifically, to a highly dense and strongly insulating ultra-thick carbon-doped ceramic coating and its preparation method. Background Technology

[0002] Titanium alloys, stainless steel, aluminum alloys, and other metallic materials are widely used in marine vessels, aerospace, petrochemicals, and other fields. However, in harsh corrosive environments, the surfaces of these metals suffer severe corrosion. Furthermore, when dissimilar metal components are assembled and contacted, a significant potential difference leads to galvanic corrosion. Material corrosion poses a serious threat to the safety and reliability of components, potentially causing accidents and economic losses. Therefore, insulation and corrosion protection technologies for metal surfaces are crucial for development in various fields.

[0003] The prior art with application number CN202211572430.1 discloses an ultra-thick carbon-based composite coating with a heterogeneous multilayer structure, its preparation method and application. The ultra-thick carbon-based composite coating includes a transition layer and alternating stacked layers formed sequentially on the surface of a substrate. The alternating stacked layers are formed by alternating layers of heterogeneous structure layers and amorphous carbon layers. The heterogeneous structure layers include any one or a combination of two or more of MeC layers, MeN layers, and MeCN layers, where Me is selected from Cr, Ti or W. The outermost layer of the ultra-thick carbon-based composite coating is an amorphous carbon layer. The main problems with this prior art are as follows: (1) The magnetron sputtering technology requires the deposition of a multilayer structure, and the preparation method is relatively complex; (2) The total thickness of the composite coating using magnetron sputtering technology is only 26 μm. During long-term use, once damaged, the substrate is easily corroded; (3) This composite coating cannot achieve ultra-thickness, high density, high insulation, high bonding strength and high wear resistance. Summary of the Invention

[0004] In view of this, the present invention aims to propose a highly dense and strongly insulating ultra-thick carbon-doped ceramic coating and its preparation method. This addresses the problems of existing technologies that require the deposition of multi-layer structures using magnetron sputtering, resulting in complex preparation methods; the total thickness of composite coatings using magnetron sputtering is only 26 μm, and the substrate is easily corroded if damaged during long-term use; and the inability of such composite coatings to achieve ultra-thickness, high density, high insulation, high bonding strength, and high wear resistance.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A method for preparing a highly dense and strongly insulating ultrathick carbon-doped ceramic coating includes the following steps:

[0007] S1. Substrate pretreatment: The pretreatment includes polishing and chemical cleaning in sequence;

[0008] S2, Plasma sputtering cleaning;

[0009] S3. Deposition of the underlayer; the underlayer is a Ti / TiC underlayer or a Cr / CrN underlayer;

[0010] S4. Deposit a carbon-based intermediate layer on the base layer;

[0011] S5. Deposit a C / SiO2 / Al2O3 ceramic surface layer on the carbon-based intermediate layer.

[0012] This setup improves the film-substrate adhesion between the ceramic top layer and the substrate by depositing a Ti / TiC or Cr / CrN underlayer on the substrate; the carbon-based intermediate layer enhances the substrate bearing capacity and acts as a template to force the amorphization growth of the top carbon film; the C / SiO2 / Al2O3 ceramic top layer deposited in the carbon-based intermediate layer has high insulation strength and can provide excellent insulation; the ultra-thick C / SiO2 / Al2O3 ceramic top layer can improve the overall corrosion resistance of the ceramic coating.

[0013] Preferably, when the substrate is a titanium alloy, Ti / TiC is used as the underlayer; when the substrate is stainless steel, aluminum alloy or other metal material, Cr / CrN is deposited as the underlayer.

[0014] Furthermore, the thickness of the underlayer is 0.2-0.8 μm, the thickness of the carbon-based intermediate layer is 2-10 μm, the thickness of the C / SiO2 / Al2O3 ceramic surface layer is 10-50 μm, and the total thickness of the ultra-thick carbon-doped ceramic coating is 45-60 μm.

[0015] This setup controls the thickness of the underlayer to improve the bonding strength and corrosion resistance between the film and the substrate; controls the thickness of the intermediate layer to improve the substrate's load-bearing capacity and to act as a template to force the amorphization growth of the top carbon film, thereby increasing the thickness of the ceramic surface layer; and controls the thickness of the ceramic surface layer to improve its insulation performance.

[0016] Further, step S3 specifically involves using a titanium or chromium target as the sputtering raw material, argon as the sputtering gas, and methane or nitrogen as the reaction gas to deposit a Ti / TiC or Cr / CrN underlayer on the substrate surface.

[0017] Further, in step S3, the argon flow rate is 30-35 sccm, the methane or nitrogen flow rate is 150-175 sccm, the voltage is -600 to -800 V, the current is 20 to 25 A, and the deposition time is 30 to 40 min.

[0018] Further, step S4 specifically involves turning off the titanium or chromium target, using argon as the sputtering gas, methane as the reaction gas, and hydrogen as the reaction gas to deposit a carbon-based intermediate layer on the substrate.

[0019] Furthermore, in step S4, the furnace heating temperature is 160-220℃, the methane flow rate is 80-120 sccm, the hydrogen flow rate is 320-800 sccm, the power is 1200-1600W, the bias voltage is -800--1000V, the current is 10A, and the deposition time is 2-3h.

[0020] Further, step S5 specifically involves using graphite, aluminum, or silicon targets as sputtering raw materials, argon as the sputtering gas, and oxygen as the reaction gas, and employing a DC reactive sputtering process to deposit a C / SiO2 / Al2O3 ceramic surface layer on a carbon-based intermediate layer.

[0021] Further, in step S5, a pulse bias voltage of 10–20 kV, a pulse width of 20–30 microseconds, a pulse frequency of 150–200 Hz, an argon working pressure of 0.3–0.5 Pa, an oxygen flow rate of 30–50 sccm, and a deposition time of 10–20 hours are applied.

[0022] Furthermore, the surface roughness of the polished substrate is less than 0.5 μm, preferably 0.2 to 0.5 μm.

[0023] Compared to existing technologies, the method for preparing a highly dense and strongly insulating ultra-thick carbon-doped ceramic coating described in this invention has the following advantages:

[0024] 1) This invention improves the film-substrate adhesion between the ceramic surface layer and the substrate by depositing a Ti / TiC or Cr / CrN underlayer on the substrate; the carbon-based intermediate layer is used to improve the substrate bearing capacity and act as a template to force the amorphous growth of the top carbon film; the C / SiO2 / Al2O3 ceramic surface layer deposited in the carbon-based intermediate layer has high insulation strength and can play a good insulation role; the ultra-thick C / SiO2 / Al2O3 ceramic surface layer is used to prepare a ceramic coating, which can improve the corrosion resistance of the entire ceramic coating.

[0025] 2) The preparation method of the present invention can realize the preparation of ultra-thick carbon-doped ceramic coatings with high density and strong insulation on the surface of metals such as titanium alloys, stainless steel, and aluminum alloys. The total thickness of the ceramic coating can reach 40-60 μm, with an insulation strength of 700-1100 MΩ, an adhesion strength of 25-40 N, a hardness of 600-1000 HV, and the film remains intact and uncorroded after 3000 hours of salt spray testing. The ceramic coating of the present invention can simultaneously achieve high density, high insulation, high adhesion, and high wear resistance.

[0026] 3) The preparation method of the present invention is simple. It only requires depositing three layers on the substrate to obtain a highly dense and strong insulating ultra-thick carbon-doped ceramic coating.

[0027] The present invention also provides a highly dense and strongly insulating ultra-thick carbon-doped ceramic coating, which is obtained by the preparation method described above.

[0028] The high-density, high-insulation ultra-thick carbon-doped ceramic coating described above has the same advantages over the prior art as the preparation method of the high-density, high-insulation ultra-thick carbon-doped ceramic coating described above, and will not be repeated here. Attached Figure Description

[0029] Figure 1 This is a structural appearance diagram of the ceramic coating in Embodiment 1 of the present invention;

[0030] Figure 2 This is a cross-sectional topography diagram of the ceramic coating in Embodiment 1 of the present invention;

[0031] Figure 3 The image shows the surface morphology of the ceramic coating of Example 1 of the present invention after a 3000-hour neutral salt spray corrosion test.

[0032] Figure 4 This is a microscopic morphology diagram of the ceramic coating of Embodiment 1 of the present invention;

[0033] Figure 5 This is a structural appearance diagram of the ceramic coating in Embodiment 2 of the present invention;

[0034] Figure 6 This is a cross-sectional topography diagram of the ceramic coating in Embodiment 2 of the present invention;

[0035] Figure 7 This is a surface morphology diagram of the ceramic coating of Example 2 of the present invention after a 3000-hour neutral salt spray corrosion test;

[0036] Figure 8 This is a microscopic morphology diagram of the ceramic coating of Embodiment 2 of the present invention. Detailed Implementation

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0038] This invention prepares carbon-doped ceramic coatings on the surfaces of metals such as stainless steel, titanium alloys, and aluminum alloys. First, a 0.2-0.8 μm Ti / TiC or Cr / CrN underlayer is formed on the substrate surface using a multi-arc ion plating method. Then, the working gas is adjusted to argon, methane, and hydrogen, and the power and gas partial pressure are set to generate a 2-10 μm carbon-based thin film intermediate layer. Next, a sputtering process is used, simultaneously activating graphite, aluminum, and silicon targets, and adjusting the working gas to argon and oxygen, to generate a 10-50 μm thick C / SiO2 / Al2O3 ceramic coating through a composite reaction. The underlayer is used to improve the film-substrate adhesion between the ceramic film and the substrate; the carbon-based intermediate layer is used to improve the substrate load-bearing capacity and act as a template to force the amorphous growth of the top carbon film; and the C / SiO2 / Al2O3 ceramic coating is used to improve insulation strength and wear resistance.

[0039] The preparation process of a high-density, high-insulation, ultra-thick carbon-doped ceramic coating according to the present invention is as follows:

[0040] Step 1: Polishing and chemical cleaning; The surface of the stainless steel / titanium alloy metal parts is polished using chemical processes to a surface roughness of 0.2-0.5μm, followed by ultrasonic cleaning with acetone, anhydrous ethanol, and deionized water for 10-20 minutes in sequence, and then dried.

[0041] Step 2: Ion sputtering cleaning: Place the cleaned workpiece into the reaction chamber substrate frame, evacuate the chamber, and bring the chamber pressure to 1.0–9.0 × 10⁻⁶. -3 Pa, argon gas is introduced for high-energy plasma sputtering cleaning, the argon gas flow rate is 50-80 sccm, argon gas is used as sputtering gas, the cleaning time is 30-40 min, the sputtering chamber pressure is 0.5 Pa, and the sputtering power is 600 W;

[0042] Step 3: Ti / TiC or Cr / CrN Underlayer: The titanium or chromium target is controlled by the cathode. The working gas is argon and methane or nitrogen. The argon flow rate is 30-35 sccm, while the methane or nitrogen flow rate is 150-175 sccm. The voltage is -600 to -800V, the current is 20 to 25A, and the deposition time is 30 to 40 minutes, forming a transitional Ti / TiC or Cr / CrN underlayer. This setup improves the adhesion strength between the film and the substrate and enhances corrosion resistance.

[0043] Step 4: Carbon-based Intermediate Layer: Turn off the titanium or chromium target. Adjust the working gas to methane, hydrogen, and argon. The argon flow rate is 30-40 sccm, the furnace temperature is applied to 160-220℃, the methane flow rate is 80-120 sccm, the hydrogen flow rate is 320-800 sccm, the power is 1200-1600W, the bias voltage is -800 to -1000V, the current is 10A, and the deposition time is 2-3 hours. A 2-10 micrometer thick carbon-based intermediate layer is formed on the substrate surface. This improves the substrate's insulation strength and corrosion resistance.

[0044] Step 5: C / SiO2 / Al2O3 ceramic coating: Using DC reactive sputtering, the graphite target, aluminum target, and silicon target are simultaneously turned on. The working gas is adjusted to argon and oxygen. A pulse bias voltage of 10-20 kV, a pulse width of 20-30 microseconds, a pulse frequency of 150-200 Hz, an argon working pressure of 0.3-0.5 Pa, an oxygen flow rate of 30-80 sccm, and a deposition time of 10-20 hours are applied. The composite reaction generates a C / SiO2 / Al2O3 ceramic coating with a thickness of 10-50 micrometers.

[0045] This invention utilizes a vapor-phase coupled ion plating method. This process employs cathode arc discharge, which exhibits good diffraction properties, ensuring the uniformity of the coating layer. This invention is suitable for preparing coatings on the surfaces of irregularly shaped parts and can overcome the challenges of coating deposition within deep holes. Furthermore, this invention disperses and doespes multiple insulating ceramic phases onto a carbon-based thin film, effectively improving the film's insulation properties. The film prepared by this invention exhibits high density, excellent insulation, and significant thickness, effectively preventing galvanic corrosion between dissimilar metals.

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

[0047] Example 1

[0048] This invention relates to a method for preparing a highly dense and strongly insulating ultra-thick carbon-doped ceramic coating, comprising the following steps:

[0049] Step 1, Polishing and Cleaning: The surface of the stainless steel metal parts is polished using a chemical polishing process to a surface roughness of 0.25μm. Then, it is ultrasonically cleaned for 10 minutes in sequence with acetone, anhydrous ethanol, and deionized water, and then dried.

[0050] Step 2, Ion Sputtering Cleaning: Place the cleaned substrate from Step 1 onto the substrate rack in the reaction chamber of the magnetron sputtering equipment, and evacuate the chamber to a pressure of 2.0 × 10⁻⁶. -3Pa, argon gas was introduced for high-energy plasma sputtering cleaning, the argon gas flow rate was 55 sccm, argon gas was used as the sputtering gas, the cleaning time was 30 min, the sputtering chamber pressure was 0.5 Pa, and the sputtering power was 600 W;

[0051] Step 3: Deposition of Cr / CrN underlayer: Using a chromium target as the sputtering material, controlled by the cathode, argon is used as the sputtering gas, and nitrogen is used as the reaction gas. The argon flow rate is 30 sccm, the nitrogen flow rate is 160 sccm, the voltage is -700V, the current is 25A, and the deposition time is 30min, depositing a 0.3μm thick Cr / CrN underlayer on the substrate surface. This setup for depositing the Cr / CrN underlayer is used to improve the film-substrate adhesion between the ceramic surface layer and the substrate.

[0052] Step 4: Deposit a carbon-based intermediate layer: Turn off the chromium target, adjust the working gas to methane, hydrogen, and argon, with an argon flow rate of 35 sccm, a furnace temperature of 200℃, a methane flow rate of 100 sccm, a hydrogen flow rate of 500 sccm, a power of 1500W, a bias voltage of -850V, a current of 10A, and a reaction time of 2.5h. Deposit a 3μm thick carbon-based intermediate layer on the Cr / CrN underlayer. This intermediate carbon-based intermediate layer is used to improve the substrate bearing capacity and act as a template to force the amorphization growth of the top carbon film, thereby improving the substrate's insulation strength and corrosion resistance.

[0053] Step 5: Deposition of C / SiO2 / Al2O3 ceramic surface layer: DC reactive sputtering process is used, with graphite target, aluminum target and silicon target turned on simultaneously, working gas is adjusted to argon and oxygen, pulse bias voltage is applied to 20kV, pulse width is 20 microseconds, pulse frequency is 150Hz, argon working pressure is 0.4Pa, oxygen flow rate is 35sccm, deposition time is 12 hours, and a 41μm thick C / SiO2 / Al2O3 ceramic surface layer is deposited on carbon-based intermediate layer.

[0054] The ceramic coating prepared on the stainless steel metal component in Example 1, such as Figure 1 As shown; the total thickness of the ceramic coating is 43.17-45.59 μm; the ceramic coating was tested and obtained with an insulation strength of 750 MΩ, an adhesion strength of 38 N, and a hardness of 830 HV; the film remained intact and showed no corrosion after 3000 hours of salt spray testing. Figure 3 As shown; the membrane structure is dense, such as Figure 4 As shown.

[0055] Example 2

[0056] This invention relates to a method for preparing a highly dense and strongly insulating ultra-thick carbon-doped ceramic coating, comprising the following steps:

[0057] Step 1, Polishing and Cleaning: The surface of the titanium alloy metal parts is polished using a chemical polishing process to a surface roughness of 0.35μm. Then, it is ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 20 minutes in sequence, and then dried.

[0058] Step 2, Ion Sputtering Cleaning: Place the cleaned substrate from Step 1 onto the substrate rack in the reaction chamber of the magnetron sputtering equipment, and evacuate the chamber to a pressure of 7.5 × 10⁻⁶. -3 Pa, argon gas was introduced for high-energy plasma sputtering cleaning, the argon gas flow rate was 80 sccm, argon gas was used as the sputtering gas, the cleaning time was 30 min, the sputtering chamber pressure was 0.5 Pa, and the sputtering power was 600 W;

[0059] Step 3: Deposition of the Ti / TiC underlayer: Using a titanium target as the sputtering material, controlled by the cathode, argon is used as the sputtering gas, and methane is used as the reactant gas. The argon flow rate is 35 sccm, the methane flow rate is 175 sccm, the voltage is -800V, the current is 25A, and the deposition time is 40 min, depositing a 0.5 μm thick Ti / TiC underlayer on the substrate surface. This setup improves the bonding strength between the film and the substrate and its corrosion resistance. Furthermore, the titanium carbide layer acts as a template, inducing the amorphous growth of the carbon-based intermediate layer.

[0060] Step 4: Deposit a carbon-based intermediate layer: The working gas is adjusted to methane, hydrogen, and argon, with an argon flow rate of 30 sccm, a furnace temperature of 180℃, a methane flow rate of 100 sccm, a hydrogen flow rate of 700 sccm, a power of 1400W, a bias voltage of -850V, a current of 10A, and a reaction time of 3h. A 2μm thick carbon-based intermediate layer is deposited on the Ti / TiC substrate. This setup improves the substrate's insulation strength and corrosion resistance.

[0061] Step 5: Deposition of C / SiO2 / Al2O3 ceramic surface layer: DC reactive sputtering process is used, with graphite target, aluminum target and silicon target turned on simultaneously, working gas is adjusted to argon and oxygen, pulse bias voltage is applied to 12kV, pulse width is 25 microseconds, pulse frequency is 200Hz, argon working pressure is 0.3Pa, oxygen flow rate is 80sccm, deposition time is 20 hours, and a 43μm thick C / SiO2 / Al2O3 ceramic surface layer is deposited on carbon-based intermediate layer.

[0062] The ceramic coating prepared on the titanium alloy component in Example 2 is as follows: Figure 5 As shown; the total thickness of the ceramic coating is 43.71-46.81 μm, as... Figure 6 As shown; the ceramic coating was tested and found to have an insulation strength of 800 MΩ, an adhesion strength of 36 N, and a hardness of 780 HV; after 3000 hours of salt spray testing, the film remained intact and showed no corrosion. Figure 7 As shown; the membrane structure is dense, such as Figure 8 As shown.

[0063] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for preparing a highly dense and strongly insulating ultra-thick carbon-doped ceramic coating, characterized in that, Includes the following steps: S1. Substrate pretreatment: The pretreatment includes polishing and chemical cleaning in sequence; S2, Plasma sputtering cleaning; S3. Deposition of the underlayer; the underlayer is a Ti / TiC underlayer or a Cr / CrN underlayer; S4. Deposit a carbon-based intermediate layer on the base layer; S5. Deposit a C / SiO2 / Al2O3 ceramic surface layer on the carbon-based intermediate layer; The thickness of the underlayer is 0.2-0.8 μm, the thickness of the carbon-based intermediate layer is 2-10 μm, the thickness of the C / SiO2 / Al2O3 ceramic surface layer is 10-50 μm, and the total thickness of the ultra-thick carbon-doped ceramic coating is 45-60 μm; the insulation strength of the ultra-thick carbon-doped ceramic coating is 700-1100 MΩ, the adhesion strength is 25-40 N, the hardness is 600-1000 HV, and the film remains intact and uncorroded after 3000 hours of salt spray testing. Step S3 specifically involves using a titanium or chromium target as the sputtering raw material, argon as the sputtering gas, and methane or nitrogen as the reaction gas to deposit a Ti / TiC or Cr / CrN underlayer on the substrate surface. Step S4 specifically involves turning off the titanium or chromium target, using argon as the sputtering gas, methane as the reaction gas, and hydrogen as the reaction gas to deposit a carbon-based intermediate layer on the Ti / TiC or Cr / CrN underlayer. Step S5 specifically involves using graphite, aluminum, and silicon targets as sputtering raw materials, argon as the sputtering gas, and oxygen as the reaction gas, and employing a DC reactive sputtering process to deposit a C / SiO2 / Al2O3 ceramic surface layer on a carbon-based intermediate layer. In step S3, the argon flow rate is 30-35 sccm, the methane or nitrogen flow rate is 150-175 sccm, the voltage is -600 to -800 V, the current is 20 to 25 A, and the deposition time is 30 to 40 min. In step S4, the furnace heating temperature is 160-220℃, the methane flow rate is 80-120 sccm, the hydrogen flow rate is 320-800 sccm, the power is 1200-1600W, the bias voltage is -800--1000V, the current is 10A, and the deposition time is 2-3h. In step S5, a pulse bias voltage of 10–20 kV, a pulse width of 20–30 microseconds, a pulse frequency of 150–200 Hz, an argon working pressure of 0.3–0.5 Pa, an oxygen flow rate of 30–80 sccm, and a deposition time of 10–20 hours are applied.

2. The preparation method according to claim 1, characterized in that, The surface roughness of the substrate after polishing is less than 0.5 μm.

3. A highly dense and strongly insulating ultra-thick carbon-doped ceramic coating, characterized in that, It is obtained by the preparation method described in any one of claims 1 to 2.

Images