Modified chromium carbide-based cermet coating and method for its production and use

Abstract

The application discloses a modified chromium carbide-based cermet coating and a preparation method and application thereof, and belongs to the technical field of coating materials. The preparation of the coating comprises the following steps: performing surface texturing pretreatment on a metal base material with a chromium carbide-based cermet coating to form micron-level micropores; and coating a composite high-temperature lubricating phase mixture on the surface of the chromium carbide-based cermet coating with the micron-level micropores, and melting and filling the composite high-temperature lubricating phase mixture into the micron-level micropores by using a high-temperature vacuum negative pressure immersion method. The preparation method is simple and easy to operate, and the prepared modified chromium carbide-based cermet coating has good wear resistance and friction reduction performance. After a multi-cycle tribological performance test at 25 DEG C to 800 DEG C, the modified chromium carbide-based cermet coating exhibits excellent low-friction coefficient lubrication performance, and the wide-temperature-range tribological performance of a traditional chromium carbide-based cermet coating is greatly improved, so that an innovative solution is provided for the service life design of high-temperature moving parts.

Description

Technical Field

[0001] This invention relates to the field of coating materials technology, and more specifically, to a modified chromium carbide-based cermet coating, its preparation method, and its application. Background Technology

[0002] With the rapid development of industries such as aerospace, marine engineering, and new energy, the high-temperature wear problem of key moving components such as gas turbine drive bearings and aircraft engine blades is becoming increasingly prominent, seriously affecting the service life of the workpieces. Under high-temperature environments, the lubricating film on the surface of traditional materials is prone to failure, leading to direct contact between the friction pair and the substrate, causing severe wear. This makes wide-temperature-range lubrication modification of the friction interface particularly important.

[0003] Currently, most engineering moving parts utilize liquid or solid lubricants to improve lubrication performance. However, liquid lubricants are highly volatile and have poor load-bearing capacity, especially at temperatures exceeding 400°C, where they rapidly fail. Traditional solid lubricants are easily oxidized at temperatures above 500°C, leading to a sharp decline in lubrication performance. Furthermore, the addition of a lubricating phase affects the overall mechanical properties of the material, resulting in decreased wear resistance. Therefore, achieving a dynamic response of the lubricating phase and stable load-bearing capacity of the supporting phase in high-temperature wear-resistant coatings across a wide temperature range remains a challenging and hot research topic.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a modified chromium carbide-based cermet coating, its preparation method, and its application, so as to solve or improve the above-mentioned technical problems.

[0006] This invention can be implemented as follows:

[0007] In a first aspect, the present invention provides a method for preparing a modified chromium carbide-based cermet coating, comprising the following steps:

[0008] A surface texturing pretreatment is performed on a metal substrate with a chromium carbide-based cermet coating to form micron-sized micropores on the surface of the chromium carbide-based cermet coating.

[0009] A composite high-temperature lubricating phase mixture is coated onto the surface of a chromium carbide-based metal ceramic coating with micron-sized micropores. The composite high-temperature lubricating phase mixture is melted and at least a portion of the composite high-temperature lubricating phase mixture is filled into the micron-sized micropores by a high-temperature vacuum negative pressure impregnation method.

[0010] The composite high-temperature lubricating phase mixture includes a high-temperature lubricating phase and the aforementioned medium- and low-temperature lubricating phases in a mass ratio of 7.5:2.5 to 8.5:1.5; wherein the high-temperature lubricating phase includes at least one of barium fluoride, calcium fluoride, and hexagonal boron nitride; and the medium- and low-temperature lubricating phases include at least two of graphite, boron oxide, bismuth oxide, Ag, Cu, MoS2, and WS2.

[0011] The conditions for high-temperature vacuum negative pressure impregnation include: temperature of 500℃~1000℃ and vacuum degree of -0.5MPa~-0.01MPa.

[0012] In an optional embodiment, the preparation of the metal substrate having a chromium carbide-based cermet coating includes: preparing a chromium carbide-based cermet coating on the surface of the metal substrate using a thermal spraying process.

[0013] Thermal spraying processes include low-pressure plasma spraying, atmospheric plasma spraying, supersonic plasma spraying, or supersonic flame spraying.

[0014] In an optional embodiment, the thermal spraying process adopts a supersonic flame spraying process, and the process conditions include: oxygen flow rate of 800L / min~1000L / min, kerosene flow rate of 20L / min~40L / min, carrier gas flow rate of 4L / min~12L / min, and powder feeding rate of 50g / min~120g / min.

[0015] In optional embodiments, the surface texture pretreatment method includes at least one of nanosecond laser processing, picosecond laser processing, femtosecond laser processing, cutting, and chemical etching.

[0016] In an optional implementation, the surface texture pretreatment includes at least one of the following features:

[0017] Feature 1: Surface texture pretreatment is performed using nanosecond laser processing. The process conditions include: laser power of 150W~200W, wavelength of 900nm~1100nm, scanning speed of 800mm / s~1000mm / s, and laser irradiation intensity of 0.1J / mm². 2 ~0.3J / mm 2 Processing gases include nitrogen;

[0018] Feature 2: The center-to-center distance between two adjacent micro-sized pores is 500μm~1000μm;

[0019] Feature 3: The longitudinal depth of the micropores is 40μm~80μm.

[0020] In an optional embodiment, the particle size of the composite high-temperature lubricating phase mixture is 1 μm to 10 μm.

[0021] Secondly, the present invention provides a modified chromium carbide-based cermet coating, which is prepared by any of the preparation methods described in the foregoing embodiments.

[0022] Thirdly, the present invention provides a component having the modified chromium carbide-based cermet coating of the aforementioned embodiments.

[0023] In an optional embodiment, the thickness of the chromium carbide-based cermet coating is 100 μm to 300 μm.

[0024] Fourthly, the present invention provides an application of the component as described in the foregoing embodiments in a wear-resistant and friction-reducing mechanical structure.

[0025] The beneficial effects of this invention include:

[0026] This invention pre-treats the surface of a metal substrate with a chromium carbide-based cermet coating by texturing the surface. The resulting micron-sized pores on the chromium carbide-based cermet coating surface effectively store wear debris generated during friction, thus reducing friction. Furthermore, these micron-sized pores can effectively store lubricant, which is continuously extruded during subsequent service life, further optimizing the friction interface. This invention uses a composite high-temperature lubricant phase mixture to fill the micron-sized pores through a high-temperature vacuum negative pressure impregnation process, resulting in a high-load-bearing and wear-resistant lubricating coating with wide-temperature-range lubrication properties. This significantly improves the tribological properties of traditional chromium carbide-based cermet coatings over a wide temperature range and extends the coating's wide-temperature-range lubrication life.

[0027] The modified chromium carbide-based cermet coating prepared by the above method has both good anti-wear and friction-reducing properties. After multiple cycles of tribological performance testing at 25℃~800℃, it showed excellent lubrication performance with a low coefficient of friction, which greatly improved the wide-temperature-range tribological performance of traditional chromium carbide-based cermet coatings and provided an innovative solution for the life extension design of high-temperature moving parts. Attached Figure Description

[0028] 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.

[0029] Figure 1 The XRD patterns of Cr3C2-NiCr powder and Cr3C2-NiCr coating in Experiment Example 1 are shown.

[0030] Figure 2The images show the SEM and EDS images of the Cr3C2-NiCr coating in Experimental Example 1.

[0031] Figure 3 SEM and EDS images of the composite high-temperature lubricating phase mixture in the modified chromium carbide-based cermet coating in Experimental Example 1;

[0032] Figure 4 XPS image of the surface of the modified chromium carbide-based cermet coating in Experiment Example 1;

[0033] Figure 5 SEM and EDS images of the surface of the modified chromium carbide-based cermet coating in Experiment Example 1;

[0034] Figure 6 The friction curves of the modified chromium carbide-based cermet coating of Example 1 in Test Example 2 under different friction cycles at 25℃~800℃;

[0035] Figure 7 The friction curve of the modified chromium carbide-based cermet coating in Example 6 of Experiment 2 after four cycles at 25°C to 800°C;

[0036] Figure 8 The friction curves of the modified chromium carbide-based cermet coating of Comparative Example 1 in Experimental Example 2 after four cycles at 25℃~800℃ are shown.

[0037] Figure 9 The friction curves of the modified chromium carbide-based cermet coating of Comparative Example 2 in Experimental Example 2 after four cycles at 25℃~800℃ are shown.

[0038] Figure 10 The friction curves of the modified chromium carbide-based cermet coating of Comparative Example 3 in Experimental Example 2 after four cycles at 25℃~800℃ are shown. Detailed Implementation

[0039] 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.

[0040] The modified chromium carbide-based cermet coating, its preparation method, and its application provided by this invention will be described in detail below.

[0041] This invention provides a method for preparing a modified chromium carbide-based cermet coating, comprising the following steps:

[0042] S1: Perform surface texturing pretreatment on a metal substrate with a chromium carbide-based cermet coating to form micron-sized micropores on the surface of the chromium carbide-based cermet coating.

[0043] In some alternative embodiments, the preparation of a metal substrate having a chromium carbide-based cermet coating may include: preparing a chromium carbide-based cermet coating on the surface of the metal substrate using a thermal spraying process.

[0044] The thermal spraying process may include, but is not limited to, low-pressure plasma spraying, atmospheric plasma spraying, supersonic plasma spraying, or supersonic flame spraying.

[0045] In some typical implementations, the thermal spraying process employs supersonic flame spraying. The process conditions for supersonic flame spraying may include: oxygen flow rate of 800 L / min to 1000 L / min, kerosene flow rate of 20 L / min to 40 L / min, carrier gas flow rate of 4 L / min to 12 L / min, and powder feeding rate of 50 g / min to 120 g / min.

[0046] The oxygen flow rate can be 800L / min, 850L / min, 900L / min, 950L / min or 1000L / min, or other values ​​within the range of 800L / min to 1000L / min.

[0047] The kerosene flow rate can be 20L / min, 25L / min, 30L / min, 35L / min or 40L / min, or other values ​​within the range of 20L / min to 40L / min.

[0048] The oxygen and kerosene flow rates mentioned above mainly affect the degree of melting of the powder in the flame.

[0049] The carrier gas flow rate can be 4L / min, 5L / min, 6L / min, 7L / min, 8L / min, 9L / min, 10L / min, 11L / min or 12L / min, or other values ​​within the range of 4L / min to 12L / min.

[0050] The aforementioned carrier gas flow rate directly affects the degree of powder heating in the flame, significantly influencing the coating's microstructure, mechanical properties, chemical stability, and spraying efficiency. If the carrier gas flow rate is below 4 L / min, the powder will remain in the flame for a relatively long time, potentially leading to overheating and excessive melting or even burn-off (e.g., accelerated oxidation of easily oxidized materials), resulting in problems such as coarse grains and increased brittleness in the coating. If the carrier gas flow rate is above 12 L / min, it will dilute the fuel and oxygen in the flame, lowering the flame temperature and shortening the powder's residence time in the high-temperature zone, resulting in insufficient powder melting (or even a "semi-solid" state). Unmelted particles are more likely to appear in the coating, thus increasing porosity.

[0051] The powder feeding rate can be 50g / min, 60g / min, 70g / min, 80g / min, 90g / min, 100g / min, 110g / min or 120g / min, or other values ​​within the range of 50g / min to 120g / min.

[0052] The powder feed rate mentioned above affects both the deposition effect and the deposition efficiency of chromium carbide-based cermet coatings. Improper powder feed rate settings can easily lead to high porosity in the chromium carbide-based cermet coating and even defects such as cracks.

[0053] In some alternative embodiments, the porosity of the chromium carbide-based cermet coating does not exceed 1%.

[0054] In some alternative implementations, the chromium carbide-based metal ceramic coating on the surface of the metal substrate is first polished and cleaned, and then a surface texture pretreatment is performed.

[0055] In some alternative implementations, the surface texture pretreatment may, by way of example but not limitation, include at least one of nanosecond laser processing, picosecond laser processing, femtosecond laser processing, cutting, and chemical etching.

[0056] In some more limited embodiments, surface texture pretreatment is performed using nanosecond laser processing. The process conditions for nanosecond laser processing may include: laser power of 150W~200W, wavelength of 900nm~1100nm, scanning speed of 800mm / s~1000mm / s, and laser irradiation intensity of 0.1J / mm². 2 ~0.3J / mm 2 The processing gases include nitrogen.

[0057] The laser power can be 150W, 160W, 170W, 180W, 190W or 200W, or other values ​​within the range of 150W to 200W.

[0058] The wavelength can be 900nm, 950nm, 1000nm, 1050nm or 1100nm, or other values ​​in the range of 900nm to 1100nm.

[0059] The scanning speed can be 800mm / s, 850mm / s, 900mm / s, 950mm / s or 1000mm / s, or other values ​​within the range of 800mm / s to 1000mm / s.

[0060] The laser irradiation intensity can be 0.1 J / mm. 2 0.15J / mm 2 0.2J / mm 2 0.25J / mm 2 or 0.3J / mm 2 Etc., can also be 0.1 J / mm 2 ~0.3J / mm 2 Other values ​​within the range.

[0061] Among these factors, laser power affects the processing accuracy of the micropores in the texture. If the laser power is below 150W, the coating material is difficult to completely vaporize, which can easily lead to the micropores not forming properly; if the laser power is above 200W, the coating material can be over-burned, affecting the texture morphology.

[0062] In this invention, the shape of the micron-sized pores obtained by surface texture pretreatment is not limited, and can be set as circles, rectangles, triangles, polygons or other irregular shapes as needed.

[0063] In some optional embodiments, the micron-sized micropores on the surface of the chromium carbide-based cermet coating are arranged in a regular pattern; in other optional embodiments, the micron-sized micropores on the surface of the chromium carbide-based cermet coating may also be arranged irregularly. In some more typical embodiments, the micron-sized micropores on the surface of the chromium carbide-based cermet coating are arranged in a regular pattern.

[0064] In some optional implementations, the center distance between two adjacent micrometer-sized micropores can be 500μm to 1000μm, such as 500μm, 550μm, 600μm, 650μm, 700μm, 750μm, 800μm, 850μm, 900μm, 950μm or 1000μm, or other values ​​within the range of 500μm to 1000μm.

[0065] The center-to-center distance between two adjacent micron-sized micropores can characterize the distribution density of micron-sized micropores on the surface of the chromium carbide-based cermet coating. It should be noted that a smaller center-to-center distance between two adjacent micron-sized micropores indicates a greater number of micron-sized micropores on the surface of the chromium carbide-based cermet coating, which is more conducive to accommodating a larger amount of composite high-temperature lubricating phase mixture, thus improving lubrication performance. However, at the same time, the mass of the chromium carbide-based cermet coating will decrease, resulting in a smaller supporting force of the entire modified chromium carbide-based cermet coating. This invention specifically controls the center-to-center distance between two adjacent micron-sized micropores to 500 μm to 1000 μm, which can ensure lubrication while also taking into account appropriate supporting force.

[0066] In some alternative implementations, the longitudinal depth of the micron-sized micropores can be 40μm to 80μm, such as 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm or 80μm, or other values ​​within the range of 40μm to 80μm.

[0067] Similarly, the deeper the longitudinal depth of the micron-sized micropores, the more suitable it is to accommodate a larger mixture of complex high-temperature lubricating phases, thus improving lubrication performance; however, at the same time, the quality of the chromium carbide-based cermet coating will decrease, resulting in a smaller supporting force of the entire modified chromium carbide-based cermet coating. This invention specifically sets the longitudinal depth of the micron-sized micropores to 40μm~80μm, which can ensure lubrication while also taking into account appropriate supporting force.

[0068] As mentioned above, the micron-sized pores formed on the surface of the chromium carbide-based metal ceramic coating can effectively store the wear debris generated during friction, thus reducing friction. In addition, it can effectively store lubricant. The lubricant impregnated in the micron-sized pores can be continuously squeezed out during the subsequent service of the product, further optimizing the friction interface.

[0069] S2: The composite high-temperature lubricating phase mixture is coated on the surface of a chromium carbide-based metal ceramic coating with micron-sized micropores, and the composite high-temperature lubricating phase mixture is melted and at least part of the composite high-temperature lubricating phase mixture is filled into the micron-sized micropores by high-temperature vacuum negative pressure impregnation.

[0070] In some optional embodiments, the particle size of the composite high-temperature lubricating phase mixture can be 1μm to 10μm, such as 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm, or other values ​​in the range of 1μm to 10μm.

[0071] In some alternative embodiments, the composite high-temperature lubricating phase mixture includes at least a medium-low temperature lubricating phase, which may exemplarily include at least two of graphite, boron oxide, bismuth oxide, Ag, Cu, MoS2 and WS2.

[0072] In some typical embodiments, the lubricating phase in the medium- and low-temperature range includes graphite, boron oxide, and bismuth oxide. Among these, boron oxide and bismuth oxide exhibit superior high-temperature stability and resistance to high-temperature oxidation. It should be noted that the inventors have creatively discovered that combining graphite with boron oxide and bismuth oxide, which are low-melting-point oxides, can achieve a synergistic effect in lubrication and friction reduction. Furthermore, at high temperatures, the low-melting-point oxides are in a glassy molten state, exhibiting significant resistance to high-temperature oxidation. They can encapsulate refractory lubricating phase particles (such as incompletely molten bismuth oxide and fluorides), stably existing within the microporous structure of the chromium carbide-based cermet coating surface. This provides effective high-temperature oxidation protection for the encapsulated refractory lubricating phase particles, ensuring effective lubrication at higher temperatures.

[0073] In some alternative embodiments, the composite high-temperature lubricant mixture may include a high-temperature lubricant phase and a medium-low temperature lubricant phase in a mass ratio of 7.5:2.5 to 8.5:1.5. Exemplarily, the mass ratio of the high-temperature lubricant phase to the medium-low temperature lubricant phase may be 7.5:2.5, 8:2, or 8.5:1.5, or other values ​​within the range of 7.5:2.5 to 8.5:1.5. The high-temperature lubricant phase may, exemplarily, include at least one of barium fluoride, calcium fluoride, and hexagonal boron nitride.

[0074] In some optional embodiments, the mixing method of the lubricating phases contained in the composite high-temperature lubricating phase mixture is not limited, and can be at least one of mechanical dry grinding, mechanical wet grinding, and semi-dry grinding. In some more typical embodiments, the mixing method of the lubricating phases contained in the composite high-temperature lubricating phase mixture is mechanical dry grinding.

[0075] In some preferred embodiments, each micron-sized pore is filled with a composite high-temperature lubricating phase mixture.

[0076] In some alternative embodiments, the conditions for high-temperature vacuum negative pressure impregnation may include: a temperature of 500°C to 1000°C and a vacuum degree of -0.5MPa to -0.01MPa.

[0077] The temperature for high-temperature vacuum negative pressure impregnation can be 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃ or 1000℃, or other values ​​within the range of 500℃ to 1000℃.

[0078] The vacuum degree of high-temperature vacuum negative pressure impregnation can be -0.5MPa, -0.4MPa, -0.3MPa, -0.2MPa, -0.1MPa, -0.05MPa or -0.01MPa, or other values ​​within the range of -0.5MPa to -0.01MPa.

[0079] The time for high-temperature vacuum negative pressure impregnation is not limited, as long as the composite high-temperature lubricating phase mixture can be impregnated into micron-sized micropores. For example, the high-temperature vacuum negative pressure impregnation time can be 10 min to 5 min, such as 10 min, 30 min, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h.

[0080] The aforementioned high-temperature vacuum negative pressure impregnation can be carried out by coating a composite high-temperature lubricating phase mixture onto the surface of a chromium carbide-based metal ceramic coating with micron-level micropores, and then placing it in a high-temperature vacuum muffle furnace for impregnation under high temperature and vacuum conditions.

[0081] The vacuum level has a significant impact on the impregnation effect of the glassy lubricating phase. If the vacuum level is less than -0.5 MPa, the glassy lubricating phase may not be able to completely fill the microporous structure of the coating surface; if the vacuum level is higher than -0.01 MPa, it will increase the vacuuming time and significantly increase the sample preparation cost.

[0082] Continuing from the above, this invention uses a mixture of multiple substances as a composite high-temperature lubricating phase mixture, and then fills the composite lubricant into micron-sized micropores through a high-temperature vacuum negative pressure impregnation process, which can obtain a high load-bearing and wear-resistant lubricating coating with a wide temperature range lubrication effect, significantly improve the tribological properties of traditional chromium carbide-based metal ceramic coatings in a wide temperature range, and enhance the wide temperature range lubrication life of the coating.

[0083] Accordingly, the present invention also provides a modified chromium carbide-based cermet coating, which is prepared by the above-described preparation method.

[0084] This modified chromium carbide-based cermet coating has both good wear resistance and friction reduction properties. After multiple cycles of friction in the range of 25℃ to 800℃, the coefficient of friction can be below 0.2.

[0085] In addition, the present invention also provides a component having the above-described modified chromium carbide-based cermet coating.

[0086] In some alternative embodiments, the thickness of the chromium carbide-based cermet 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.

[0087] Furthermore, the present invention also provides an application of the above-mentioned components in a wear-resistant and friction-reducing mechanical structure with a wide temperature range.

[0088] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0089] Example 1

[0090] This embodiment provides a modified chromium carbide-based cermet coating, the preparation method of which includes:

[0091] S11: Prepare a metal substrate with a chromium carbide-based cermet coating.

[0092] A Cr3C2-NiCr coating was prepared on the surface of a 316L stainless steel substrate using a supersonic flame spraying process. The raw material for the spraying was commercially available Cr3C2-NiCr powder (particle size 21μm~54μm), and the thickness of the Cr3C2-NiCr coating was 200μm. The supersonic flame spraying process conditions included: oxygen flow rate of 900L / min, kerosene flow rate of 30L / min, carrier gas flow rate of 8L / min, and powder feeding rate of 100g / min.

[0093] S12: Surface texture pretreatment.

[0094] The Cr3C2-NiCr coating was polished to a roughness of 0.2 μm, followed by ultrasonic cleaning to remove contaminants and debris generated during polishing. Circular micron-sized micropores were fabricated on the surface of the chromium carbide-based cermet coating using nanosecond laser processing. The nanosecond laser processing conditions included: laser power of 180 W, wavelength of 1064 nm, scanning speed of 900 mm / s, and laser irradiation intensity of 0.15 J / mm². 2 The processing gas is nitrogen. The center-to-center distance between two adjacent micro-sized pores is 800 μm, and the longitudinal depth of the micro-sized pores is 60 μm.

[0095] S21: A uniformly mixed composite high-temperature lubricating phase mixture with a particle size of 1μm~10μm is coated onto the surface of a chromium carbide-based metal ceramic coating with micron-sized micropores.

[0096] The composite high-temperature lubricating phase mixture is obtained by mechanically mixing graphite, boron oxide and bismuth oxide powders (particle size of 1μm~5μm) in a mass ratio of 3:3:4.

[0097] S22: The composite high-temperature lubricating phase mixture is heated to a molten state by high-temperature vacuum negative pressure impregnation, and then impregnated into micron-sized micropores by negative pressure to obtain a modified chromium carbide-based metal ceramic coating (Cr3C2-NiCr-B2O3 / Bi2O3 / C composite coating).

[0098] The process conditions for high-temperature vacuum negative pressure impregnation include: temperature of 800℃, vacuum degree of -0.1MPa, and vacuum impregnation time of 3h.

[0099] Example 2

[0100] The difference between this embodiment and Embodiment 1 is that:

[0101] In S11, the supersonic flame spraying process conditions include: oxygen flow rate of 800 L / min, kerosene flow rate of 20 L / min, carrier gas flow rate of 4 L / min, and powder feeding rate of 50 g / min. The thickness of the Cr3C2-NiCr coating is 100 μm.

[0102] In S12, the process conditions for nanosecond laser processing include: laser power of 150W, wavelength of 900nm, scanning speed of 800mm / s, and laser irradiation intensity of 0.1J / mm². 2 The processing gas is nitrogen. The center-to-center distance between two adjacent micro-sized pores is 500 μm, and the longitudinal depth of the micro-sized pores is 40 μm. The cross-sectional shape of the micro-sized pores is rectangular.

[0103] In S21, the composite high-temperature lubricating phase mixture is obtained by mechanically mixing graphite, boron oxide and bismuth oxide powders (particle size of 1μm~5μm) in a mass ratio of 1:4:5.

[0104] In S22, the process conditions for high-temperature vacuum negative pressure impregnation include: temperature of 500℃, vacuum degree of -0.5MPa, and vacuum impregnation time of 10min.

[0105] Example 3

[0106] The difference between this embodiment and Embodiment 1 is that:

[0107] In S11, the supersonic flame spraying process conditions include: oxygen flow rate of 1000 L / min, kerosene flow rate of 40 L / min, carrier gas flow rate of 12 L / min, and powder feeding rate of 120 g / min. The thickness of the Cr3C2-NiCr coating is 300 μm.

[0108] In S12, the process conditions for nanosecond laser processing include: laser power of 200W, wavelength of 1100nm, scanning speed of 1000mm / s, and laser irradiation intensity of 0.3J / mm². 2 The processing gas is nitrogen. The center-to-center distance between two adjacent micro-sized pores is 1000 μm, and the longitudinal depth of the micro-sized pores is 80 μm. The cross-sectional shape of the micro-sized pores is triangular.

[0109] In S21, the composite high-temperature lubricating phase mixture is obtained by mechanically mixing graphite, boron oxide and bismuth oxide powders (particle size of 1μm~5μm) in a mass ratio of 2:3:5.

[0110] In S22, the process conditions for high-temperature vacuum negative pressure impregnation include: temperature of 1000℃, vacuum degree of -0.01MPa, and vacuum impregnation time of 5h.

[0111] Example 4

[0112] The difference between this embodiment and Embodiment 1 is that the composite high-temperature lubricating phase mixture consists only of graphite and boron oxide, and the total amount of the composite high-temperature lubricating phase mixture and the amount of graphite are the same as in Embodiment 1.

[0113] Example 5

[0114] The difference between this embodiment and Embodiment 1 is that the composite high-temperature lubricating phase mixture consists only of graphite and bismuth oxide, and the total amount of the composite high-temperature lubricating phase mixture and the amount of graphite are the same as in Embodiment 1.

[0115] Example 6

[0116] The difference between this embodiment and Embodiment 1 is that the composite high-temperature lubricating phase mixture consists only of boron oxide and bismuth oxide, and the total amount of the composite high-temperature lubricating phase mixture and the amount of boron oxide are the same as in Embodiment 1.

[0117] Example 7

[0118] The difference between this embodiment and Embodiment 1 is that the composite high-temperature lubricating phase mixture consists of a high-temperature lubricating phase and a medium-low temperature lubricating phase in a mass ratio of 8:2. Specifically, the medium-low temperature lubricating phase is composed of graphite, boron oxide, and bismuth oxide powders (particle size 1 μm to 5 μm) in a mass ratio of 3:3:4, and the high-temperature lubricating phase is barium fluoride.

[0119] Comparative Example 1

[0120] This comparative example is the metal substrate with a chromium carbide-based cermet coating prepared in S11 of Example 1.

[0121] Comparative Example 2

[0122] The difference between this comparative example and Example 1 is that the surface texture pretreatment in S12 was not performed.

[0123] Comparative Example 3

[0124] The difference between this comparative example and Example 1 is that the lubricating phase is only graphite, and the total amount of the lubricating phase is the same as that in Example 1.

[0125] Comparative Example 4

[0126] The difference between this comparative example and Example 1 is that the powder feeding rate for supersonic flame spraying is 40 g / min.

[0127] Comparative Example 5

[0128] The difference between this comparative example and Example 1 is that the powder feeding rate for supersonic flame spraying is 150 g / min.

[0129] Comparative Example 6

[0130] The difference between this comparative example and Example 1 is that the center distance between two adjacent micro-sized micropores is 400 μm.

[0131] Comparative Example 7

[0132] The difference between this comparative example and Example 1 is that the center distance between two adjacent micro-sized micropores is 1200 μm.

[0133] Comparative Example 8

[0134] The difference between this comparative example and Example 1 is that the longitudinal depth of the micropores is 20 μm.

[0135] Comparative Example 9

[0136] The difference between this comparative example and Example 1 is that the longitudinal depth of the micropores is 100 μm.

[0137] Comparative Example 10

[0138] The difference between this comparative example and Example 1 is that the high-temperature vacuum negative pressure impregnation temperature is 1200°C.

[0139] Comparative Example 11

[0140] The difference between this comparative example and Example 1 is that the high-temperature vacuum negative pressure impregnation pressure is -0.6MPa.

[0141] Experimental Example 1

[0142] (1) XRD tests were performed on the Cr3C2-NiCr powder and Cr3C2-NiCr coating in step S11 of Example 1, and the results are as follows: Figure 1 As shown in the figure, the characteristic peaks of the Cr3C2-NiCr powder and the Cr3C2-NiCr coating are basically consistent, indicating that no significant phase transition occurred during the preparation of the Cr3C2-NiCr coating.

[0143] The Cr3C2-NiCr coating in step S11 of Example 1 was analyzed by SEM and EDS, and the results are as follows: Figure 2As shown in the figure, (a) is the SEM microstructure of the Cr3C2-NiCr coating surface, (b) is a magnified view of the framed area in (a), (c) shows the Cr and Ni element distribution in (b); (d) is the SEM microstructure of the Cr3C2-NiCr coating cross-section, (e) is a magnified view of the framed area in (d), and (f) shows the Cr and Ni element distribution in (e). Figure 2 It can be seen that the Cr3C2-NiCr coating is in good overall condition, with a dense structure and no obvious defects such as microcracks and pores. Moreover, the coating elements are evenly distributed, with no obvious element segregation or enrichment.

[0144] (2) The composite high-temperature lubricating phase mixture in the modified chromium carbide-based cermet coating prepared in Example 1 was analyzed by SEM and EDS, and the results are as follows: Figure 3 As shown, Figure 3 (a) is a SEM image of the composite high-temperature lubricating phase mixture in the modified chromium carbide-based cermet coating, and (b) is an EDS image of the composite high-temperature lubricating phase mixture in the modified chromium carbide-based cermet coating. Figure 3 It can be seen that the three lubricating phase powders (graphite, boron oxide and bismuth oxide) are mixed in a uniform state, with no obvious agglomeration and consistent particle size distribution.

[0145] XPS was tested on the surface of the modified chromium carbide-based cermet coating prepared in Example 1, and the results are as follows: Figure 4 As shown, (a) represents the full spectrum of the test region, (b) represents the fine spectrum of Bi element in the test region, (c) represents the fine spectrum of B element in the test region, and (d) represents the fine spectrum of O element in the test region. Figure 4 It can be seen that obvious graphite, boron oxide and bismuth oxide characteristics were detected on the surface of the modified chromium carbide-based metal ceramic coating.

[0146] The surface of the modified chromium carbide-based cermet coating prepared in Example 1 was analyzed by SEM and EDS, and the results are as follows: Figure 5 As shown. Figure 5 (a) is a SEM image of the modified chromium carbide-based cermet coating surface; (b) is a magnified view of the area within the box in (a); (c) is the corresponding EDS image of (a); and (d) is the corresponding EDS image of (b). Figure 5 It can be seen that the elements in the composite high-temperature lubricating phase mixture are uniformly distributed and fully fill the micron-sized micropores. The microstructure of the composite high-temperature lubricating phase mixture is dense, with no obvious cracks or pores observed, and the graphite particles are uniformly distributed and embedded in the molten boron oxide and bismuth oxide. Boron oxide and bismuth oxide have a significant high-temperature antioxidant protection effect on the graphite particles.

[0147] Experimental Example 2

[0148] The tribological properties of the modified chromium carbide-based cermet coatings prepared in the following examples and comparative examples were characterized using an HT-1000 high-temperature tribological testing machine. The characterization conditions were as follows: the mode was a ball-and-disc type, the paired ball was an alumina ball with a diameter of 5 mm, the test used a load of 5 N, a rotation speed of 500 r / min, a rotation radius of 3 mm, and a friction time of 10 min / 30 min. The tribological properties were studied based on the above parameters.

[0149] The friction curves of the modified chromium carbide-based cermet coating in Example 1 under different friction cycles at 25°C to 800°C are shown below. Figure 6 As shown, Figure 6 (a) corresponds to the result at 25℃, (b) corresponds to the result at 400℃, and (c) corresponds to the result at 800℃. From Figure 6 As can be seen, the modified chromium carbide-based cermet coating exhibits a low coefficient of friction (approximately COF < 0.2) after four cycles of tribological performance testing in each temperature range. In this embodiment, the coefficients of friction of the modified chromium carbide-based cermet coating after four cycles in each temperature range of 25℃ to 800℃ are as follows: 25℃, COF = 0.05; 400℃, COF = 0.11; 800℃, COF = 0.09. With the increase of the number of friction cycles, the coefficient of friction of the composite coating shows a decreasing trend, indicating that a friction lubrication film has been formed on the surface of the mating spheres, and this composite lubricating phase has significant wide-temperature-range lubrication characteristics.

[0150] The coefficients of friction of the modified chromium carbide-based cermet coating in Example 2 after four cycles at 25°C to 800°C were as follows: 25°C, COF=0.08; 400°C, COF=0.13; 800°C, COF=0.12.

[0151] The coefficients of friction of the modified chromium carbide-based cermet coating in Example 3 after four cycles at 25°C to 800°C were as follows: 25°C, COF=0.06; 400°C, COF=0.12; 800°C, COF=0.11.

[0152] The coefficients of friction of the modified chromium carbide-based cermet coating in Example 4 after four cycles at 25°C to 800°C were: 25°C, COF=0.05; 400°C, COF=0.18; 800°C, COF=0.13.

[0153] The coefficients of friction of the modified chromium carbide-based cermet coating in Example 5 after four cycles at 25°C to 800°C were as follows: 25°C, COF=0.06; 400°C, COF=0.16; 800°C, COF=0.14.

[0154] The friction curve of the modified chromium carbide-based cermet coating in Example 6 after four cycles at 25°C to 800°C is shown below. Figure 7 As shown in the figure, the coefficients of friction of the modified chromium carbide-based cermet coating at each temperature range are: 25℃, COF=0.36; 400℃, COF=0.69; 800℃, COF=0.11. This indicates that the modified chromium carbide-based cermet coating does not have a significant lubricating effect at temperatures between 25℃ and 400℃, because it inherently lacks low-temperature lubrication properties. At a high temperature of 800℃, the low-melting-point oxide lubricating phase is in a glassy state and exhibits good lubrication.

[0155] The coefficients of friction of the modified chromium carbide-based cermet coating in Example 7 after four cycles at 25°C to 800°C were as follows: 25°C, COF=0.09; 400°C, COF=0.14; 800°C, COF=0.12.

[0156] The friction curve of the Cr3C2-NiCr coating of Comparative Example 1 after four cycles at 25℃~800℃ is shown below. Figure 8 As shown in the figure, the coefficients of friction of the Cr3C2-NiCr coating at different temperature ranges are: 25℃, COF=0.81; 400℃, COF=0.46; 800℃, COF=0.47. This indicates that the coating has no lubricating effect in the temperature range of 25℃ to 800℃.

[0157] The friction curves of the modified chromium carbide-based cermet coating of Comparative Example 2 after four cycles at 25℃~800℃ are shown below. Figure 9 As shown in the figure, the coefficients of friction of the modified chromium carbide-based cermet coating at different temperature ranges are: 25℃, COF=0.62; 400℃, COF=0.65; 800℃, COF=0.49. This indicates that the modified chromium carbide-based cermet coating has no lubricating effect in the temperature range of 25℃ to 800℃, and the coefficient of friction curve fluctuates drastically. This is because the lubricating phase on the coating surface cannot stably exist at the friction interface and cannot stably exert the friction-reducing effect of the lubricating phase.

[0158] The friction curve of the modified chromium carbide-based cermet coating of Comparative Example 3 after four cycles at 25℃~800℃ is shown below. Figure 10As shown in the figure, the coefficients of friction of the modified chromium carbide-based cermet coating at different temperature ranges are: 25℃, COF=0.12; 400℃, COF=0.35; 800℃, COF=0.41. This indicates that the modified chromium carbide-based cermet coating has a good lubrication effect at 25℃, but as the temperature increases to 400~800℃, its lubrication effect gradually decreases and the coefficient of friction increases. This is because low-temperature lubricating phases such as graphite are easily oxidized at high temperatures, leading to the loss of their lubrication effect.

[0159] The coefficients of friction of the modified chromium carbide-based cermet coating of Comparative Example 4 after four cycles at 25℃ to 800℃ were: 25℃, COF=0.35; 400℃, COF=0.41; 800℃, COF=0.39.

[0160] The coefficients of friction of the modified chromium carbide-based cermet coating of Comparative Example 5 after four cycles at 25℃ to 800℃ were: 25℃, COF=0.33; 400℃, COF=0.42; 800℃, COF=0.44.

[0161] The coefficients of friction of the modified chromium carbide-based cermet coating of Comparative Example 6 after four cycles at 25℃~800℃ were: 25℃, COF=0.43; 400℃, COF=0.44; 800℃, COF=0.42.

[0162] The coefficients of friction of the modified chromium carbide-based cermet coating of Comparative Example 7 after four cycles at 25℃ to 800℃ were: 25℃, COF=0.48; 400℃, COF=0.46; 800℃, COF=0.45.

[0163] The coefficients of friction of the modified chromium carbide-based cermet coating of Comparative Example 8 after four cycles at 25℃ to 800℃ were: 25℃, COF=0.51; 400℃, COF=0.48; 800℃, COF=0.49.

[0164] The coefficients of friction of the modified chromium carbide-based cermet coating of Comparative Example 9 in each temperature range from 25℃ to 800℃ were as follows: 25℃, COF=0.39; 400℃, COF=0.36; 800℃, COF=0.38.

[0165] The coefficients of friction of the modified chromium carbide-based cermet coating of Comparative Example 10 after four cycles at 25℃ to 800℃ were: 25℃, COF=0.44; 400℃, COF=0.39; 800℃, COF=0.41.

[0166] The coefficients of friction of the modified chromium carbide-based cermet coating of Comparative Example 11 after four cycles at 25℃ to 800℃ were: 25℃, COF=0.31; 400℃, COF=0.33; 800℃, COF=0.35.

[0167] In summary, the modified chromium carbide-based cermet coating prepared by the method provided by this invention has both good anti-wear and friction-reducing properties. After multiple cycles of tribological performance testing within the temperature range of 25℃ to 800℃, it exhibits excellent lubrication performance with a low coefficient of friction, which significantly improves the wide-temperature-range tribological performance of traditional chromium carbide-based cermet coatings and provides an innovative solution for extending the service life of high-temperature moving parts.

[0168] 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 modified chromium carbide-based cermet coating, characterized in that, Includes the following steps: A surface texture pretreatment is performed on a metal substrate with a chromium carbide-based cermet coating to form micron-sized micropores on the surface of the chromium carbide-based cermet coating. A composite high-temperature lubricating phase mixture is coated onto the surface of the chromium carbide-based metal ceramic coating having micron-sized micropores. The composite high-temperature lubricating phase mixture is melted and at least a portion of the composite high-temperature lubricating phase mixture is filled into the micron-sized micropores by a high-temperature vacuum negative pressure impregnation method. The composite high-temperature lubricating phase mixture includes a high-temperature lubricating phase and a medium-low temperature lubricating phase in a mass ratio of 7.5:2.5 to 8.5:1.5; wherein the high-temperature lubricating phase includes at least one of barium fluoride, calcium fluoride and hexagonal boron nitride, and the medium-low temperature lubricating phase includes at least two of graphite, boron oxide, bismuth oxide, Ag, Cu, MoS2 and WS2. The conditions for high-temperature vacuum negative pressure impregnation include: temperature of 500℃~1000℃ and vacuum degree of -0.5MPa~-0.01MPa; The preparation of the metal substrate with the chromium carbide-based metal ceramic coating includes: preparing the chromium carbide-based metal ceramic coating on the surface of the metal substrate using a thermal spraying process; Thermal spraying processes include low-pressure plasma spraying, atmospheric plasma spraying, supersonic plasma spraying, or supersonic flame spraying. Surface texture pretreatment methods include at least one of nanosecond laser processing, picosecond laser processing, femtosecond laser processing, machining, and chemical etching; Surface texture pretreatment includes at least one of the following features: Feature 1: Surface texture pretreatment is performed using nanosecond laser processing. The process conditions include: laser power of 150W~200W, wavelength of 900nm~1100nm, scanning speed of 800mm / s~1000mm / s, and laser irradiation intensity of 0.1J / mm². 2 ~0.3J / mm 2 Processing gases include nitrogen; Feature 2: The center-to-center distance between two adjacent micro-sized pores is 500μm~1000μm; Feature 3: The longitudinal depth of the micro-sized pores is 40μm~80μm.

2. The preparation method according to claim 1, characterized in that, The thermal spraying process adopts supersonic flame spraying technology, and the process conditions include: oxygen flow rate of 800L / min~1000L / min, kerosene flow rate of 20L / min~40L / min, carrier gas flow rate of 4L / min~12L / min, and powder feeding rate of 50g / min~120g / min.

3. The preparation method according to claim 1, characterized in that, The particle size of the composite high-temperature lubricating phase mixture is 1μm~10μm.

4. A modified chromium carbide-based cermet coating, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 3.

5. A component, characterized in that, The component has the modified chromium carbide-based metal ceramic coating as described in claim 4.

6. The application of the component as described in claim 5 in a wear-resistant and friction-reducing mechanical structure.

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