Ceramic-based self-lubricating high-wear-resistance composite coating as well as preparation method and application thereof

Abstract

The invention discloses a ceramic-based self-lubricating high-wear-resistance composite coating as well as a preparation method and application thereof, and belongs to the technical field of wear-resistant coatings. The preparation method of the composite coating comprises the following steps: preparing a ceramic coating on the surface of a metal substrate in a thermal spraying manner; the preparation method comprises the following steps: firstly, preparing a ceramic coating, then carrying out first vacuum impregnation treatment in a reactant solution containing sodium molybdate and thiourea, and then carrying out hydrothermal reaction to synthesize molybdenum disulfide in part of pores and cracks of the ceramic coating so as to obtain a thermal spraying ceramic coating containing molybdenum disulfide; and the thermal spraying ceramic coating containing molybdenum disulfide is subjected to second-time vacuum dipping treatment in the molten solid-liquid reversible lubricating phase, then cooling is conducted, so that the solid-liquid reversible lubricating phase is solidified and reserved in remaining pores and cracks of the ceramic coating, and the ceramic-based self-lubricating high-abrasion-resistance composite coating is obtained. The ceramic-based self-lubricating high-wear-resistance composite coating prepared by the method has good antifriction, wear resistance and mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of wear-resistant coating technology, and more specifically, to a ceramic-based self-lubricating high wear-resistant composite coating, its preparation method, and its application. Background Technology

[0002] Friction, as a universal physical phenomenon of interfacial contact, always accompanies the relative motion of mechanical systems and is one of the core bottlenecks restricting the reliability and energy efficiency of high-end equipment. Optimizing the friction and wear performance of key components using surface engineering technology is an economical and efficient method. Solid lubricating coatings, by optimizing the surface composition and structure of materials, endow them with special lubrication, wear resistance, and protective properties, and are an effective way to solve friction, wear, and lubrication problems. Ceramic lubricating coatings, due to their high hardness and high strength, can achieve effective lubrication under special working conditions. However, traditional methods of adding lubricants lead to degradation of mechanical properties, weakening resistance to cracking and operational stability. Currently, a perfect solution that can effectively reduce the coefficient of friction while improving the mechanical properties of the coating has not yet been found. Therefore, there is an urgent need to develop an effective method to improve the friction reduction, wear resistance, and mechanical properties of ceramic coatings.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a ceramic-based self-lubricating high wear-resistant composite coating, its preparation method and application, in order to solve or improve the above-mentioned technical problems.

[0005] This invention can be implemented as follows: In a first aspect, the present invention provides a method for preparing a ceramic-based self-lubricating high wear-resistant composite coating, comprising the following steps: A ceramic coating was prepared on the surface of a metal substrate by thermal spraying. Then, a first vacuum impregnation treatment was performed in a reactant solution containing sodium molybdate and thiourea. Subsequently, a hydrothermal reaction was carried out to synthesize molybdenum disulfide in some pores and cracks of the ceramic coating, resulting in a thermally sprayed ceramic coating containing molybdenum disulfide. A thermally sprayed ceramic coating containing molybdenum disulfide is subjected to a second vacuum impregnation treatment in a molten solid-liquid reversible lubricating phase, followed by cooling, so that the solid-liquid reversible lubricating phase solidifies and remains in the remaining pores and cracks of the ceramic coating, resulting in a ceramic-based self-lubricating high wear-resistant composite coating.

[0006] In an optional embodiment, the ceramic coating includes at least one of the following features: Feature 1: The ceramic coating includes oxide ceramic coating, carbide ceramic coating, or nitride ceramic coating; Feature 2: The thickness of the ceramic coating is 100μm~300μm.

[0007] Feature 3: The ceramic coating is prepared by atmospheric plasma spraying. The preparation conditions of the ceramic coating include: plasma spray gun current of 450A~600A, argon flow rate of 30L / min~50L / min, hydrogen flow rate of 4L / min~12L / min, spray distance of 90mm~140mm, and powder feeding rate of 20g / min~60g / min.

[0008] In an optional embodiment, a metal transition layer is first prepared on the surface of the metal substrate by thermal spraying before preparing the ceramic coating.

[0009] In an optional embodiment, the molar ratio of sodium molybdate to thiourea is 2:5 to 2:13.

[0010] In an optional embodiment, the conditions for the first vacuum impregnation treatment include: a pressure of -0.040 MPa to -0.085 MPa, a temperature of room temperature, and a time of 10 min to 30 min.

[0011] In an optional embodiment, the hydrothermal reaction conditions include a temperature of 200°C to 300°C and a time of 10h to 36h.

[0012] In an optional embodiment, the solid-liquid reversible lubricating phase includes at least one of palm wax, microcrystalline wax, stearic acid, and paraffin wax.

[0013] In an optional embodiment, the conditions for the second vacuum impregnation treatment include: a pressure of -0.040 MPa to -0.085 MPa, a temperature of 130°C to 160°C, and a time of 40 min to 60 min.

[0014] Secondly, the present invention provides a ceramic-based self-lubricating high wear-resistant composite coating, which is prepared by any of the preparation methods described in the foregoing embodiments.

[0015] Thirdly, the present invention provides a bearing comprising the ceramic-based self-lubricating high wear-resistant composite coating of the foregoing embodiments.

[0016] The beneficial effects of this invention include: The first vacuum impregnation treatment allows the reactant solution to fully penetrate the inherent pores and cracks (including micron and / or nanon cracks) within the ceramic coating. Subsequently, under hydrothermal conditions, sodium molybdate and thiourea in the reactant solution react to form molybdenum disulfide. A second vacuum impregnation treatment is then performed on the thermally sprayed ceramic coating containing molybdenum disulfide within a molten, reversible lubricating phase, followed by cooling. This process prevents the oxidation of molybdenum disulfide within the ceramic coating defects. Furthermore, because molybdenum disulfide has a "petal-like" structure, the cooled reversible lubricating phase can fill and retain the remaining pores and cracks within the ceramic coating.

[0017] In the ceramic-based self-lubricating high-wear-resistant composite coating prepared by this method, the solid-liquid reversible lubricating phase and molybdenum disulfide can be well bonded together. During friction, the solid-liquid reversible lubricating phase and molybdenum disulfide work together to lubricate. Simultaneously, the solid-liquid reversible lubricating phase within the ceramic coating forms an oil film during friction, which can isolate oxygen and moisture from the air. Taking palm wax as an example, as the solid-liquid reversible lubricating phase proceeds, the long-chain wax ester decomposes into short chains, absorbing moisture and oxygen from the air. This dual effect of isolating and absorbing oxygen and moisture from the air slows down the oxidation of molybdenum and continuously replenishes the lubricating film. The two lubricating phases together ensure the long-term effective lubrication of the coating in atmospheric environments. Furthermore, this ceramic-based self-lubricating high-wear-resistant composite coating also possesses excellent mechanical properties. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The graph shows the test results of molybdenum disulfide powder in Experiment Example 1 of this invention; Figure 2 The image shows the test results of the YMCW coating cross-section in Experiment Example 1 of this invention; Figure 3 The test results of the Y coating, YM coating and YMCW coating surfaces in Test Example 1 of the present invention are shown in the figure. Figure 4 The mechanical property results of the YMCW coating, Y coating and YM coating in Experiment Example 2 of the present invention are shown in the figure. Figure 5 The diagram shows the tribological properties of the YMCW coating, Y coating, and YM coating in Experimental Example 3 of this invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0021] The following provides a detailed description of the ceramic-based self-lubricating high wear-resistant composite coating, its preparation method, and its application provided by the present invention.

[0022] This invention provides a method for preparing a ceramic-based self-lubricating high wear-resistant composite coating, which includes the following steps: S1: A ceramic coating is prepared on the surface of a metal substrate by thermal spraying; then a first vacuum impregnation treatment is performed in a reactant solution containing sodium molybdate and thiourea, followed by a hydrothermal reaction to synthesize molybdenum disulfide in some pores and cracks of the ceramic coating, thus obtaining a thermally sprayed ceramic coating containing molybdenum disulfide.

[0023] In some alternative embodiments, the ceramic coating may, by way of example but not limitation, include an oxide ceramic coating, a carbide ceramic coating, or a nitride ceramic coating. In some more typical embodiments, the ceramic coating is an oxide ceramic coating.

[0024] In some optional embodiments, the thickness of the ceramic coating can be 100 μm to 300 μm, such as 100 μm, 150 μm, 200 μm, 250 μm, or 300 μm, or other values ​​within the range of 100 μm to 300 μm. In some more typical embodiments, the thickness of the ceramic coating is 150 μm to 300 μm.

[0025] In some alternative embodiments, the thermal spraying method for preparing the ceramic coating may include low-pressure plasma spraying, atmospheric plasma spraying, supersonic plasma spraying, or supersonic flame spraying.

[0026] In some typical embodiments, the ceramic coating can be prepared by atmospheric plasma spraying. The preparation conditions of the ceramic coating may include: plasma spray gun current of 450A~600A (e.g., 450A, 500A, 550A or 600A), argon flow rate of 30L / min~50L / min (e.g., 30L / min, 35L / min, 40L / min, 45L / min or 50L / min), hydrogen flow rate of 4L / min~12L / min (e.g., 4L / min, 6L / min, 8L / min, 10L / min or 12L / min), spray distance of 90mm~140mm (e.g., 90mm, 100mm, 110mm, 120mm, 130mm or 140mm), and powder feeding rate of 20g / min~60g / min (e.g., 20g / min, 30g / min, 40g / min, 50g / min or 60g / min).

[0027] During the thermal spraying process of ceramic coatings, the rapid cooling of molten droplets can cause defects such as pores or microcracks, affecting mechanical properties and wear resistance. Furthermore, ceramic materials themselves have poor lubrication properties. In this invention, the ceramic coating prepared by the above method has inherent porosity and crack defects, with a porosity of approximately less than 10%.

[0028] In some alternative embodiments, a metal transition layer is first prepared on the surface of the metal substrate using thermal spraying before preparing the ceramic coating. By setting a metal transition layer between the metal underlayer and the ceramic coating, stress can be relieved and adhesion increased.

[0029] In some alternative implementations, the metal transition layer may be a NiCrAlY transition layer.

[0030] In some alternative implementations, the thickness of the metal transition layer can be 70μm to 100μm, such as 70μm, 75μm, 80μm, 85μm, 90μm, 95μm or 100μm, or other values ​​within the range of 70μm to 100μm.

[0031] In some alternative embodiments, the thermal spraying method for preparing the metal transition layer may include low-pressure plasma spraying, atmospheric plasma spraying, supersonic plasma spraying, or supersonic flame spraying.

[0032] In some typical implementations, the metal transition layer can be prepared by atmospheric plasma spraying. The preparation conditions of the metal transition layer may include: plasma spray gun current of 500A~600A, argon flow rate of 35L / min~55L / min, hydrogen flow rate of 6L / min~10L / min, spray distance of 80mm~110mm, and powder feeding rate of 30g / min~50g / min.

[0033] In some alternative implementations, the ceramic coating may be surface polished, ultrasonicated, and dried prior to the first vacuum impregnation treatment.

[0034] In some alternative embodiments, the molar ratio of sodium molybdate to thiourea can be 2:5 to 2:13, such as 2:5, 2:6, 2:7, 2:8, 2:9, 2:10, 2:11, 2:12 or 2:13, or other values ​​within the range of 2:5 to 2:13.

[0035] If the molar ratio of sodium molybdate to thiourea is less than 2:5 (e.g., 2:2), the sulfur source and reducing agent are insufficient, leading to incomplete reaction and the formation of oxygen-containing impurities. If the molar ratio of sodium molybdate to thiourea is greater than (e.g., 2:15), excessive reduction occurs, resulting in byproduct contamination and coarsening of the morphology.

[0036] In some optional embodiments, the conditions for the first vacuum impregnation treatment include: a pressure of -0.040 MPa to -0.085 MPa, a temperature of room temperature, and a time of 10 min to 30 min. Ultrasonic treatment may also be performed during this process.

[0037] The pressure for the first vacuum impregnation treatment can be -0.040MPa, -0.045MPa, -0.050MPa, -0.055MPa, -0.060MPa, -0.065MPa, -0.070MPa, -0.075MPa, -0.080MPa, or -0.085MPa, or other values ​​within the range of -0.040MPa to -0.085MPa.

[0038] If the pressure is below -0.040 MPa (e.g., -0.035 MPa), the vacuum level is insufficient, preventing the effective removal of air and contaminants from the coating pores. This reduces the solution's permeability and filling density. If the pressure is above -0.085 MPa (e.g., -0.090 MPa), the excessively high vacuum level may cause process runaway and side effects, leading to decreased economic benefits.

[0039] The time for the first vacuum impregnation treatment can be 10 min, 15 min, 20 min, 25 min or 30 min, or other values ​​within the range of 10 min to 30 min.

[0040] If the first vacuum impregnation treatment time is less than 10 minutes, the air and volatiles in the pores will not be fully removed, and the vacuum holding time will be insufficient; if the first vacuum impregnation treatment time is longer than 30 minutes, the impregnating agent may volatilize and deteriorate.

[0041] In some alternative implementations, the hydrothermal reaction conditions include a temperature of 200°C to 300°C and a time of 10 to 36 hours.

[0042] The temperature of the hydrothermal reaction can be 200℃, 220℃, 240℃, 260℃, 280℃ or 300℃, or other values ​​within the range of 200℃ to 300℃.

[0043] If the hydrothermal reaction temperature is below 200℃, the sodium molybdate reaction is likely to be incomplete; if the hydrothermal reaction temperature is above 300℃, substances such as molybdenum dioxide or molybdenum tetrasulfide are likely to be generated.

[0044] The hydrothermal reaction time can be 10h, 16h, 22h, 28h, 34h or 36h, or other values ​​within the range of 10h to 36h.

[0045] If the hydrothermal reaction time is less than 10 hours, the reaction time is insufficient, resulting in incomplete precursor transformation, poor crystallinity, and morphological defects. If the hydrothermal reaction time is longer than 36 hours, the specific surface area decreases, and rough hierarchical structures (such as nanoflowers) may collapse and fuse.

[0046] After the hydrothermal reaction, excess powder on the surface of the ceramic coating can be removed.

[0047] As mentioned above, the first vacuum impregnation treatment allows the reactant solution to fully penetrate the inherent pores and cracks (including micron and / or nano cracks) within the ceramic coating. Subsequently, under hydrothermal reaction conditions, sodium molybdate and thiourea in the reactant solution react to generate molybdenum disulfide.

[0048] S2: The thermally sprayed ceramic coating containing molybdenum disulfide is subjected to a second vacuum impregnation treatment in the molten solid-liquid reversible lubricating phase, followed by cooling, so that the solid-liquid reversible lubricating phase solidifies and remains in the remaining pores and cracks of the ceramic coating, to obtain a ceramic-based self-lubricating high wear-resistant composite coating.

[0049] In some alternative embodiments, the solid-liquid reversible lubricating phase may exemplary include at least one of palm wax, microcrystalline wax, stearic acid, and boron oxide. In some more typical embodiments, the lubricating phase is palm wax.

[0050] The heating and melting temperature of a solid-liquid reversible lubricating phase can be 70℃ to 500℃, depending on the melting point of the specific substance used.

[0051] In some alternative embodiments, the conditions for the second vacuum impregnation treatment include: a pressure of -0.040 MPa to -0.085 MPa, a temperature of 130°C to 160°C, and a time of 40 min to 60 min.

[0052] The pressure for the second vacuum impregnation treatment can be -0.040MPa, -0.045MPa, -0.050MPa, -0.055MPa, -0.060MPa, -0.065MPa, -0.070MPa, -0.075MPa, -0.080MPa, or -0.085MPa, or other values ​​within the range of -0.040MPa to -0.085MPa.

[0053] If the pressure is below -0.040MPa (e.g., -0.035MPa), the vacuum is insufficient, meaning that the pressure difference (the difference between atmospheric pressure and the pressure inside the can) that propels the wax forward is too small, making it difficult to effectively penetrate into tiny pores and deep holes, resulting in incomplete sealing. If the pressure is above -0.085MPa (e.g., -0.090MPa), it may cause the low-boiling-point components in the palm wax to volatilize, damaging the wax's composition.

[0054] The temperature for the second vacuum impregnation treatment can be 130℃, 135℃, 140℃, 145℃, 150℃, 155℃ or 160℃, or other values ​​within the range of 130℃ to 160℃.

[0055] If the temperature of the second vacuum impregnation treatment is below 130°C, the palm wax may be in a semi-molten paste or completely solid state with extremely high viscosity and poor fluidity, making it impossible to flow into micron or even nano-sized pores under pressure difference, and the penetration process can hardly take place; if the temperature of the second vacuum impregnation treatment is above 160°C, overheating may cause the volatility of the wax to increase significantly.

[0056] The time for the second vacuum impregnation treatment can be 40 min, 45 min, 50 min, 55 min or 60 min, or other values ​​within the range of 40 min to 60 min.

[0057] After cooling, excess solid-liquid reversible lubricating phase can be removed from the surface of the ceramic coating.

[0058] Continuing from the above, by subjecting the thermally sprayed ceramic coating containing molybdenum disulfide to a second vacuum impregnation treatment in the molten solid-liquid reversible lubricating phase and then cooling it, on the one hand, the oxidation of molybdenum disulfide in the defects of the ceramic coating can be avoided; on the other hand, since molybdenum disulfide has a "petal-like" structure, the solid-liquid reversible lubricating phase can fill and retain the pores and cracks that still exist in the ceramic coating after cooling.

[0059] Accordingly, the present invention also provides a ceramic-based self-lubricating high wear-resistant composite coating, which is prepared by the above-described preparation method.

[0060] In this ceramic-based self-lubricating high-wear-resistant composite coating, the reversible solid-liquid lubricating phase and molybdenum disulfide can be well bonded together. During friction, the reversible solid-liquid lubricating phase and molybdenum disulfide work together to lubricate. Simultaneously, the reversible solid-liquid lubricating phase within the ceramic coating forms an oil film during friction, isolating oxygen and moisture from the air. Taking palm wax as an example, as friction progresses, long-chain wax esters decompose into short chains, absorbing moisture and oxygen from the air. This dual effect of isolating and absorbing oxygen and moisture slows down the oxidation of molybdenum. Furthermore, under the localized high temperatures generated during friction, the reversible solid-liquid lubricating phase within the ceramic coating softens or even melts, overflowing to replenish the lubricating film. Together, these two lubricating phases ensure long-term effective lubrication of the coating in atmospheric conditions.

[0061] Building upon the above, the ceramic-based self-lubricating high-wear-resistant composite coating provided by this invention possesses excellent friction reduction, wear resistance, and mechanical properties. Furthermore, this ceramic-based self-lubricating high-wear-resistant composite coating can ensure low wear on the grinding surface while maintaining good self-wear resistance.

[0062] Furthermore, the present invention also provides a bearing comprising the aforementioned ceramic-based self-lubricating high-wear-resistant composite coating. For example, the surface of the bearing has the aforementioned ceramic-based self-lubricating high-wear-resistant composite coating.

[0063] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0064] Example 1 This embodiment provides a ceramic-based self-lubricating high wear-resistant composite coating, the preparation method of which includes: S1-1: An atmospheric plasma spraying process was used to first prepare a 100 μm thick NiCrAlY transition layer on the surface of a stainless steel substrate (the raw material was commercially available NiCrAlY powder with a particle size of 80 μm to 100 μm, purchased from Höganäs). Then, a 300 μm thick yttrium-stabilized zirconia coating was prepared on the surface of the NiCrAlY transition layer (the raw material was commercially available yttrium-stabilized zirconia powder with a particle size of 22 μm to 45 μm, purchased from Höganäs).

[0065] The conditions for preparing the NiCrAlY transition layer include: plasma spray gun current of 600A, argon flow rate of 50L / min, hydrogen flow rate of 8L / min, spray distance of 100mm, and powder feeding rate of 40g / min.

[0066] The conditions for preparing yttrium-stabilized zirconia coatings include: plasma spray gun current of 550A, argon flow rate of 35L / min, hydrogen flow rate of 12L / min, spray distance of 100mm, and powder feed rate of 20g / min.

[0067] S1-2: Polish the sprayed yttrium-stabilized zirconia coating to a roughness of 0.2 μm, followed by ultrasonication and drying.

[0068] S1-3: Add 29.2g of sodium molybdate (provided by Shanghai Aladdin Biochemical Technology Co., Ltd., grade S433698) and 43.25g of thiourea (provided by Shanghai Aladdin Biochemical Technology Co., Ltd., grade T112514) to 250mL of deionized water under magnetic stirring to obtain a reactant solution with a molar ratio of sodium molybdate to thiourea of ​​2:8. Place the substrate with the yttrium oxide-stabilized zirconia coating obtained in S1-2 into the prepared reactant solution, and then perform a first vacuum impregnation treatment for 15min at -0.085MPa and room temperature.

[0069] S1-4: The material obtained in S1-3 is passed into a hydrothermal reactor and heated to 280°C. The temperature is maintained for 12 hours to carry out the hydrothermal reaction. After the reaction is completed, the excess powder on the surface of the ceramic coating is removed to obtain a thermally sprayed ceramic coating containing molybdenum disulfide, namely, a yttrium oxide stabilized zirconia / molybdenum disulfide composite coating (named YM).

[0070] S2-1: The solid-liquid reversible lubricant palm wax (provided by Shanghai Aladdin Biochemical Technology Co., Ltd., brand name C104041) was heated to above 140 °C in a vacuum drying oven to melt it. The yttrium oxide stabilized zirconia / molybdenum disulfide composite coating of S1-4 was immersed in the melted palm wax and subjected to a second vacuum impregnation treatment for 40 min at -0.08 MPa and 150 °C.

[0071] S2-2: Take out the product after the second vacuum impregnation treatment, cool it to room temperature, remove excess palm wax from the coating surface, and obtain a ceramic-based self-lubricating high wear-resistant composite coating, namely the yttrium oxide stabilized zirconium oxide / molybdenum disulfide / palm wax composite coating (named YMCW coating).

[0072] Example 2 The difference between this embodiment and Embodiment 1 is that the solid-liquid reversible lubricant is replaced with stearic acid (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., brand name S108289).

[0073] The ceramic-based self-lubricating high wear-resistant composite coating obtained in this embodiment is a yttrium oxide-stabilized zirconia / molybdenum disulfide / stearic acid composite coating (named YMYZ coating).

[0074] Example 3 The difference between this embodiment and Embodiment 1 is that the solid-liquid reversible lubricant is replaced with microcrystalline wax (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., brand name C304667).

[0075] The ceramic-based self-lubricating high wear-resistant composite coating obtained in this embodiment is a yttrium oxide-stabilized zirconia / molybdenum disulfide / microcrystalline wax composite coating (named YMWJ coating).

[0076] Example 4 The difference between this embodiment and Embodiment 1 is that the solid-liquid reversible lubricant is replaced with paraffin wax (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., brand name P104801).

[0077] The ceramic-based self-lubricating high wear-resistant composite coating obtained in this embodiment is a yttrium oxide-stabilized zirconium oxide / molybdenum disulfide / microcrystalline wax composite coating (named YMMF coating).

[0078] Example 5 This embodiment provides a ceramic-based self-lubricating high wear-resistant composite coating, the preparation method of which includes: S1-1: An atmospheric plasma spraying process was used to first prepare a 70 μm thick NiCrAlY transition layer on the surface of a stainless steel substrate (the raw material was commercially available NiCrAlY powder with a particle size of 80 μm to 100 μm, purchased from Höganäs). Then, a 100 μm thick yttrium-stabilized zirconia coating was prepared on the surface of the NiCrAlY transition layer (the raw material was commercially available yttrium-stabilized zirconia powder with a particle size of 22 μm to 45 μm, purchased from Höganäs).

[0079] The conditions for preparing the NiCrAlY transition layer include: plasma spray gun current of 500A, argon flow rate of 35L / min, hydrogen flow rate of 6L / min, spray distance of 90mm, and powder feeding rate of 30g / min.

[0080] The conditions for preparing yttrium-stabilized zirconia coatings include: plasma spray gun current of 450A, argon flow rate of 30L / min, hydrogen flow rate of 4L / min, spray distance of 90mm, and powder feed rate of 20g / min.

[0081] S1-2: Polish the sprayed yttrium-stabilized zirconia coating to a roughness of 0.2 μm, followed by ultrasonication and drying.

[0082] S1-3: Add 29.2g of sodium molybdate (provided by Shanghai Aladdin Biochemical Technology Co., Ltd., grade S433698) and 26.93g of thiourea (provided by Shanghai Aladdin Biochemical Technology Co., Ltd., grade T112514) to 250mL of deionized water under magnetic stirring to obtain a reactant solution with a molar ratio of sodium molybdate to thiourea of ​​2:5. Place the substrate with the yttrium oxide-stabilized zirconia coating obtained in S1-2 into the prepared reactant solution, and then perform a first vacuum impregnation treatment for 30min at -0.040MPa and room temperature.

[0083] S1-4: The material obtained in S1-3 is fed into a hydrothermal reactor and heated to 200°C. The temperature is maintained for 36 hours to carry out the hydrothermal reaction. After the reaction is completed, excess powder on the surface of the ceramic coating is removed to obtain a thermally sprayed ceramic coating containing molybdenum disulfide, namely, a yttrium oxide stabilized zirconia / molybdenum disulfide composite coating (named YM).

[0084] S2-1: The solid-liquid reversible lubricant palm wax (provided by Shanghai Aladdin Biochemical Technology Co., Ltd., grade C104041) was heated to above 140 °C in a vacuum drying oven to melt it. The yttrium oxide-stabilized zirconium oxide / molybdenum disulfide composite coating of S1-4 was immersed in the melted palm wax and subjected to a second vacuum impregnation treatment for 60 min at -0.04 MPa and 130 °C.

[0085] S2-2: Take out the product after the second vacuum impregnation treatment, cool it to room temperature, remove excess palm wax from the coating surface, and obtain a ceramic-based self-lubricating high wear-resistant composite coating, namely the yttrium oxide stabilized zirconium oxide / molybdenum disulfide / palm wax composite coating (named YMCW coating).

[0086] Example 6 This embodiment provides a ceramic-based self-lubricating high wear-resistant composite coating, the preparation method of which includes: S1-1: An 80 μm thick NiCrAlY transition layer (using commercially available NiCrAlY powder with a particle size of 80 μm to 100 μm, purchased from Höganäs) is first prepared on the surface of a stainless steel substrate using an atmospheric plasma spraying process. Then, a 150 μm thick yttrium-stabilized zirconia coating (using commercially available yttrium-stabilized zirconia powder with a particle size of 22 μm to 45 μm, purchased from Höganäs) is prepared on the surface of the NiCrAlY transition layer.

[0087] The conditions for preparing the NiCrAlY transition layer include: plasma spray gun current of 600A, argon flow rate of 55L / min, hydrogen flow rate of 10L / min, spray distance of 110mm, and powder feeding rate of 50g / min.

[0088] The conditions for preparing yttrium-stabilized zirconia coatings include: plasma spray gun current of 600A, argon flow rate of 50L / min, hydrogen flow rate of 12L / min, spray distance of 140mm, and powder feed rate of 60g / min.

[0089] S1-2: Polish the sprayed yttrium-stabilized zirconia coating to a roughness of 0.2 μm, followed by ultrasonication and drying.

[0090] S1-3: Add 29.2g of sodium molybdate (provided by Shanghai Aladdin Biochemical Technology Co., Ltd., grade S433698) and 70g of thiourea (provided by Shanghai Aladdin Biochemical Technology Co., Ltd., grade T112514) to 250mL of deionized water under magnetic stirring to obtain a reactant solution with a molar ratio of sodium molybdate to thiourea of ​​2:13. Place the substrate with the yttrium oxide-stabilized zirconia coating obtained in S1-2 into the prepared reactant solution, and then perform a first vacuum impregnation treatment for 10min at -0.060MPa and room temperature.

[0091] S1-4: The material obtained in S1-3 is fed into a hydrothermal reactor and heated to 300℃. The temperature is maintained for 10 hours to carry out the hydrothermal reaction. After the reaction is completed, excess powder on the surface of the ceramic coating is removed to obtain a thermally sprayed ceramic coating containing molybdenum disulfide, namely, a yttrium oxide stabilized zirconia / molybdenum disulfide composite coating (named YM).

[0092] S2-1: The solid-liquid reversible lubricant palm wax (provided by Shanghai Aladdin Biochemical Technology Co., Ltd., grade C104041) was heated to above 140 °C in a vacuum drying oven to melt it. The yttrium oxide-stabilized zirconium oxide / molybdenum disulfide composite coating of S1-4 was immersed in the melted palm wax and subjected to a second vacuum impregnation treatment for 40 min at -0.085 MPa and 160 °C.

[0093] S2-2: Take out the product after the second vacuum impregnation treatment, cool it to room temperature, remove excess palm wax from the coating surface, and obtain a ceramic-based self-lubricating high wear-resistant composite coating, namely the yttrium oxide stabilized zirconium oxide / molybdenum disulfide / palm wax composite coating (named YMCW coating).

[0094] Comparative Example 1 This comparative example is the coating obtained in S1-2 of Example 1, namely the yttrium oxide stabilized zirconia coating (named Y coating).

[0095] Comparative Example 2 This comparative example is the yttrium oxide stabilized zirconium oxide / molybdenum disulfide composite coating (YM coating) obtained in S1-4 of Example 1.

[0096] Comparative Example 3 The difference between this comparative example and Example 1 is as follows: The yttrium-stabilized zirconia coating obtained in S1-2 was directly immersed in molten palm wax and subjected to a second vacuum impregnation treatment for 40 minutes at -0.08 MPa and 150°C, followed by step S2-2.

[0097] That is, steps S1-3 to S1-4 were not performed in this comparative example.

[0098] The composite coating obtained in this comparative example is a yttrium oxide stabilized zirconium oxide / carnauba wax composite coating (named YCW coating).

[0099] Comparative Example 4 The difference between this comparative example and Example 1 is that no NiCrAlY transition layer is provided between the substrate and the ceramic coating.

[0100] Comparative Example 5 The difference between this comparative example and Example 1 is that in S1-3, the substrate with ceramic coating is directly placed in the reactant solution for hydrothermal reaction, that is, the first vacuum impregnation treatment is not carried out under vacuum conditions, but is immersed under normal pressure.

[0101] Comparative Example 6 The difference between this comparative example and Example 1 is that in S1-4, the molar ratio of sodium molybdate to thiourea is 2:2.

[0102] Comparative Example 7 The difference between this comparative example and Example 1 is that in S1-4, the molar ratio of sodium molybdate to thiourea is 2:15.

[0103] Comparative Example 8 The difference between this comparative example and Example 1 is that in S1-4, the pressure of the first vacuum impregnation treatment is -0.02MPa.

[0104] Comparative Example 9 The difference between this comparative example and Example 1 is that in S1-4, the pressure of the first vacuum impregnation treatment is -1 MPa.

[0105] Comparative Example 10 The difference between this comparative example and Example 1 is that the hydrothermal reaction temperature in S1-4 is 150°C.

[0106] Comparative Example 11 The difference between this comparative example and Example 1 is that the hydrothermal reaction temperature in S1-4 is 350°C.

[0107] Comparative Example 12 The difference between this comparative example and Example 1 is that in S2-1, the yttrium oxide stabilized zirconium oxide / molybdenum disulfide composite coating is directly immersed in molten palm wax at room temperature, that is, it is not subjected to a second vacuum impregnation treatment under vacuum conditions.

[0108] Comparative Example 13 The difference between this comparative example and Example 1 is that in S2-1, the pressure of the second vacuum impregnation treatment is -0.02MPa.

[0109] Comparative Example 14 The difference between this comparative example and Example 1 is that in S2-1, the pressure of the second vacuum impregnation treatment is -1 MPa.

[0110] Experimental Example 1 (1) The molybdenum disulfide powder in Example 1 was observed by scanning electron microscopy, and the results are as follows: Figure 1 As shown in (a) and (b), (b) is an enlarged view of the area within the box in (a). From Figure 1 As can be seen in (a) and (b), the molybdenum disulfide powder is in the form of nanoflowers and has obvious lamellar structure characteristics of molybdenum disulfide.

[0111] The molybdenum disulfide powder in Example 1 was observed by EDS, and the results are as follows: Figure 1 As shown in (c), by Figure 1 As can be seen from (c), the synthesized powder is composed of two elements, S and Mo, with no other impurity elements.

[0112] The molybdenum disulfide powder in Example 1 was observed by transmission electron microscopy, and the results are as follows: Figure 1 As shown in (d) and (e), (e) is an enlarged view of the boxed area in (d). Figure 1 As can be seen in (d) and (e), molybdenum disulfide exhibits a clear lamellar structure.

[0113] Figure 1 The 3D AOGF mapping results corresponding to the two boxes in (e) are as follows: Figure 1 As shown in (f), by Figure 1 As can be seen from (f), the interlayer spacing of molybdenum disulfide is approximately 0.640 nm.

[0114] (2) The cross-section of the yttrium oxide-stabilized zirconium oxide / molybdenum disulfide / carnauba wax composite coating (YMCW coating) in Example 1 was observed by transmission electron microscopy, and the results are as follows: Figure 2 As shown in (a), (b), (d), and (e), where (b) is a magnified view of the sampling point in (a), (d) is a magnified view of the boxed area in (b), and (e) is a magnified view of the boxed area in (d); the element distribution map at the sampling point in (a) is as follows. Figure 4 The 3D AOGF mapping results corresponding to the four boxes in (c) and (e) are as follows: Figure 2 As shown in (f).

[0115] according to Figure 2 The EDS analysis in (c) shows that the light-colored areas are mainly composed of carbon (C), corresponding to carnauba wax, while the black areas are composed of molybdenum (Mo) and sulfur (S), corresponding to MoS2. As the image is further magnified, as... Figure 2 (d) and Figure 2 In the middle (e), IFFT and 3D AOGF are performed in the dark area, such as... Figure 3 In (f), the stripe pattern represents the (002) crystal orientation of MoS2. The results show that a tight bond can be established between molybdenum disulfide carnauba waxes within the thermally sprayed coating through a combination of in-situ synthesis and vacuum impregnation.

[0116] (3) The surface of the yttrium oxide-stabilized zirconia coating (Y coating) in Comparative Example 1 was observed by scanning electron microscopy, and the results are as follows: Figure 3 As shown in Figure (a), the Y coating exhibits irregular pores and cracks.

[0117] (4) Scanning electron microscopy (SEM) images and elemental distribution of the yttrium oxide-stabilized zirconium oxide / molybdenum disulfide composite coating (YM coating) in Comparative Example 2 were obtained, and the results are as follows: Figure 3 As shown in (b) and (c), from Figure 3 As can be seen from (b) and (c), MoS2 was successfully introduced into the yttrium oxide-stabilized zirconia coating.

[0118] (5) Scanning electron microscopy (SEM) images and elemental distribution observations were performed on the surface of the yttrium oxide-stabilized zirconium oxide / molybdenum disulfide / carnauba wax composite coating (YMCW coating) in Example 1. The results are as follows: Figure 3 As shown in (d) to (f), it can be seen from the figures that palm wax was successfully introduced into the yttrium oxide-stabilized zirconium oxide / molybdenum disulfide composite coating (YM coating).

[0119] from Figures 1-3 It can be seen that through hydrothermal reaction and vacuum impregnation process, the solid lubricant MoS2 and the solid-liquid reversible lubricating phase palm wax are well combined and effectively filled into the inherent pores and cracks inside the ceramic coating.

[0120] Experimental Example 2 Mechanical properties were tested on the yttrium-stabilized zirconia / molybdenum disulfide / carnauba wax composite coating (YMCW coating) in Example 1, the yttrium-stabilized zirconia coating (Y coating) in Comparative Example 1, and the yttrium-stabilized zirconia / molybdenum disulfide composite coating (YM coating) in Comparative Example 2. The test methods were in accordance with GB / T22458-2008. The results are as follows. Figure 4 As shown. Figure 4 H 3 For cubic hardness, E 2 H is the square of the elastic modulus. 3 / E 2 Used to indicate resistance to plastic deformation; L C1 This represents the critical load for the scratch tester.

[0121] Figure 4 (a) shows the loading and unloading curves; (b) shows the hardness and elastic modulus; (c) shows the resistance to plastic deformation and elastic recovery rate; and (d) shows the critical loads for the three coatings.

[0122] from Figure 4 It can be seen that the hardness, elastic recovery rate, and adhesion (critical load) of the yttrium-stabilized zirconia / molybdenum disulfide / carnauba wax composite coating (YMCW coating) are significantly improved compared with the yttrium-stabilized zirconia coating (Y coating) and the yttrium-stabilized zirconia / molybdenum disulfide composite coating (YW coating).

[0123] Experimental Example 3 The following tests were conducted according to ASTM G133-22 standards using a Retchet multi-functional tribological testing machine to characterize the tribological properties of the coating. Characterization conditions included: a ball-and-disc mode with 5mm diameter alumina spheres as the paired spheres; a sliding speed of 9Hz; an amplitude of 2.5mm; and 32,400 cycles. Long-term frictional tests were performed under different loads (2N, 5N, and 8N) and the same sliding speed (9Hz) to assess the tribological properties. Weight loss and volume loss of the coating were analyzed. All tests were conducted at room temperature (25±2℃) and relative humidity (40±5%).

[0124] (1) The yttrium-stabilized zirconium oxide / molybdenum disulfide / carnauba wax composite coating (YMCW coating) prepared in Example 1 was tested according to ASTM G133-22 standard. The coefficients of friction at a sliding speed of 9 Hz and loads of 2 N, 5 N, and 8 N were as follows: Figure 5 As shown in (a), (b) and (c), from Figure 5 As can be seen from (a), (b) and (c), the average friction coefficient of the YMCW coating is reduced by 82% compared to the Y coating under an 8N load, dropping to below 0.15.

[0125] The wear resistance of the yttrium-stabilized zirconium oxide / molybdenum disulfide / carnauba wax composite coating prepared in Example 1, tested according to ASTM G133-22, is as follows: Figure 5 As shown in (d), (e), and (f), from Figure 5 As can be seen from (d), (e), and (f), the YMCW coating exhibits improved wear resistance compared to the Y and YM coatings. Under a load of 8 N and 32,400 cycles, the wear rate of the YMCW coating decreased from 1.11 × 10⁻⁶. -3 mm 3 ·N -1 ·m -1 Reduced to 2.10 × 10 -6 mm 3 ·N -1 ·m -1 .

[0126] (2) Following the same test methods and conditions as in Example 1, the average friction coefficient of the yttrium oxide stabilized zirconium oxide / molybdenum disulfide / stearic acid composite coating (YMYZ coating) prepared in Example 2 under an 8N load is shown in Table 1. It can be seen from the table that the average friction coefficient of the YMYZ coating is reduced to 0.17.

[0127] (3) Following the same test methods and conditions as in Example 1, the average friction coefficient of the yttrium oxide stabilized zirconium oxide / molybdenum disulfide / microcrystalline wax composite coating (YMWJ coating) prepared in Example 3 under an 8N load is shown in Table 1. It can be seen from the table that the average friction coefficient of the YMWJ coating is reduced to 0.16.

[0128] (4) Following the same test methods and conditions as in Example 1, the average friction coefficient of the yttrium oxide stabilized zirconium oxide / molybdenum disulfide / microcrystalline wax (YMMF coating) prepared in Example 4 under an 8N load is also shown in Table 1. It can be seen from the table that the average friction coefficient of the YMMF coating is 0.23.

[0129] (5) Following the same test methods and conditions as in Example 1 above, the friction coefficient of the yttrium-stabilized zirconia coating (Y coating) prepared in Comparative Example 1 under an 8N load was also as... Figure 5 As shown in the figure, the average friction coefficient of the Y coating is 0.78.

[0130] (6) Following the same test methods and conditions as in Example 1 above, the average coefficient of friction of the yttrium oxide-stabilized zirconium oxide / molybdenum disulfide composite coating (YM coating) prepared in Comparative Example 2 under an 8N load was also as... Figure 5 As shown in the figure, the average friction coefficient of the YM coating is 0.30, but it gradually fails and loses its lubrication ability after 10935 cycles.

[0131] (7) Following the same test methods and conditions as in Example 1 above, the yttrium-stabilized zirconium oxide / palm wax composite coating (YCW coating) prepared in Comparative Example 3 had an average friction coefficient of 0.35 under an 8N load, but gradually failed after 21,956 cycles and lost its lubrication ability.

[0132] (8) Following the same test methods and conditions as in Example 1, various performance tests were conducted on other examples and comparative examples, and the results are shown in Table 1. The average friction coefficient and wear rate correspond to the results under an 8N load.

[0133] Table 1 Test Results

[0134] As can be seen from Table 1, the ceramic-based self-lubricating high wear-resistant composite coating obtained in the embodiments of the present invention has good friction reduction, wear resistance and mechanical properties.

[0135] In summary, the solution provided by this invention has at least the following advantages: (1) This invention uses a thermally sprayed ceramic coating as a template. Molybdenum disulfide is synthesized in the inherent pores and cracks of the ceramic coating through a hydrothermal reaction. A reversible solid-liquid lubricating phase is then introduced into the coating. After heating and melting, the phase is penetrated into the remaining pores and cracks of the ceramic coating through a vacuum impregnation process. After cooling, the phase solidifies and remains in the aforementioned defects, ultimately obtaining a novel ceramic-based self-lubricating high-wear-resistant composite coating. The preparation method of this ceramic-based self-lubricating high-wear-resistant composite coating achieves excellent self-adaptive lubrication capability without affecting the comprehensive mechanical properties of the ceramic coating. By filling the defects of traditional thermally sprayed ceramic coatings, the corrosion resistance of the coating is improved, thereby achieving the unity of the structure, mechanical properties, and tribological properties of the thermally sprayed ceramic coating.

[0136] (2) By controlling the thermal spraying parameters and the conditions during vacuum impregnation of solid and liquid lubricants, the microstructure, mechanical properties and tribological properties of the coating can be controlled.

[0137] (3) When the composite coating prepared by the present invention is applied to friction conditions, a friction film with low shear strength, high hardness, high elastic modulus and strong resistance to plastic deformation can be formed on the friction surface, thereby achieving the purpose of reducing the friction coefficient and reducing wear.

[0138] (4) The solid-liquid reversible lubricating phase can penetrate into the nanoscale defects of the coating through vacuum impregnation and combine well with molybdenum disulfide. During the friction process, an oil film is formed to isolate the air. As the friction process continues, the long-chain wax ester decomposes into short-chain to absorb oxygen and moisture from the air. The dual effect slows down the oxidation of molybdenum and continuously overflows to replenish the lubricating film, ensuring the long-term effective lubrication of the coating.

[0139] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a ceramic-based self-lubricating high wear-resistant composite coating, characterized in that, Includes the following steps: A ceramic coating is prepared on the surface of a metal substrate using thermal spraying. Subsequently, a first vacuum impregnation treatment was performed in a reactant solution containing sodium molybdate and thiourea, followed by a hydrothermal reaction to synthesize molybdenum disulfide in the partial pores and cracks of the ceramic coating, resulting in a thermally sprayed ceramic coating containing molybdenum disulfide. The thermally sprayed ceramic coating containing molybdenum disulfide is subjected to a second vacuum impregnation treatment in the molten solid-liquid reversible lubricating phase, followed by cooling, so that the solid-liquid reversible lubricating phase solidifies and remains in the remaining pores and cracks of the ceramic coating, to obtain a ceramic-based self-lubricating high wear-resistant composite coating.

2. The preparation method according to claim 1, characterized in that, The ceramic coating includes at least one of the following characteristics: Feature 1: The ceramic coating includes an oxide ceramic coating, a carbide ceramic coating, or a nitride ceramic coating; Feature 2: The thickness of the ceramic coating is 100μm~300μm, preferably 150μm~300μm; Feature 3: The ceramic coating is prepared by atmospheric plasma spraying, and the preparation conditions of the ceramic coating include: plasma spray gun current of 450A~600A, argon flow rate of 30L / min~50L / min, hydrogen flow rate of 4L / min~12L / min, spray distance of 90mm~140mm, and powder feeding rate of 20g / min~60g / min.

3. The preparation method according to claim 1, characterized in that, Before preparing the ceramic coating, a metal transition layer is first prepared on the surface of the metal substrate by thermal spraying.

4. The preparation method according to claim 1, characterized in that, The molar ratio of sodium molybdate to thiourea is 2:5 to 2:

13.

5. The preparation method according to claim 1, characterized in that, The conditions for the first vacuum impregnation treatment included: pressure of -0.040MPa to -0.085MPa, temperature of room temperature, and time of 10 min to 30 min.

6. The preparation method according to claim 1, characterized in that, The conditions for the hydrothermal reaction include a temperature of 200℃~300℃ and a time of 10h~36h.

7. The preparation method according to claim 1, characterized in that, The reversible solid-liquid lubricating phase includes at least one of palm wax, microcrystalline wax, stearic acid, and paraffin wax.

8. The preparation method according to claim 1, characterized in that, The conditions for the second vacuum impregnation treatment included: pressure of -0.040MPa to -0.085MPa, temperature of 130℃ to 160℃, and time of 40min to 60min.

9. A ceramic-based self-lubricating high wear-resistant composite coating, characterized in that, The ceramic-based self-lubricating high wear-resistant composite coating is prepared by the preparation method described in any one of claims 1 to 8.

10. A bearing, characterized in that, Including the ceramic-based self-lubricating high wear-resistant composite coating as described in claim 9.

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