Wide-temperature-range modified phosphate-based self-lubricating coatings, their preparation methods and applications

Abstract

This application provides a wide-temperature-range modified phosphate-based self-lubricating coating, its preparation method, and its application. The method includes: adding CrO3 solution to polyphosphoric acid at 90°C under stirring, adding Al(OH)3 in batches, continuing stirring for 2-3 hours, and cooling to room temperature to obtain a chromium-aluminum phosphate adhesive; heating the chromium-aluminum phosphate adhesive to 110-120°C, adding fumed silica, stirring, and then adding B2O3 in batches to obtain a modified chromium-aluminum phosphate adhesive; preparing the wide-temperature-range modified phosphate-based self-lubricating coating: mixing the modified chromium-aluminum phosphate adhesive with silica sol, mixing evenly, and then adding deionized water and filler to obtain a wide-temperature-range modified phosphate-based self-lubricating coating; spraying the wide-temperature-range modified phosphate-based self-lubricating coating onto the substrate surface and sintering to form a wide-temperature-range modified phosphate-based self-lubricating coating. The self-lubricating coating provided by this application can be applied to the field of wide-temperature-range self-lubrication and corrosion protection from room temperature to 800°C.

Description

Technical Field

[0001] This application relates to the field of anti-corrosion and lubrication materials technology, and in particular to a wide-temperature-range modified phosphate-based self-lubricating coating, its preparation method and application. Background Technology

[0002] With continuous technological advancements and industrial upgrading, various equipment and key components are increasingly used in harsh environments such as high temperatures, intense wear, and corrosion. Therefore, improving their performance under complex operating conditions requires high-temperature resistant, wear-resistant, and corrosion-resistant coatings. Because components often face severe thermal expansion and contraction, as well as oxidation and corrosion during service, conventional coatings are insufficient to meet the requirements for long-term stable use. In contrast, high-temperature resistant, wear-resistant, and corrosion-resistant coatings, with their excellent thermal stability, high-temperature oxidation resistance, and good corrosion resistance, can effectively extend the service life of equipment and components, providing a reliable protective barrier under extreme conditions.

[0003] High-temperature lubrication is a critical issue in engineering applications. Traditional greases are prone to failure under high-temperature conditions due to evaporation and oxidative decomposition. In contrast, solid bonded lubricating coatings are widely used in aerospace and other fields due to their excellent wide-temperature-range anti-wear and friction-reducing properties. Phosphate-based coatings have attracted much attention due to their superior mechanical properties and high-temperature stability. They possess excellent heat resistance, strong adhesion, and outstanding corrosion resistance, making them ideal binders for anti-corrosion coatings and wear-resistant materials.

[0004] With the rapid development of high-end equipment, self-lubricating coatings not only need to have a low coefficient of friction, but also need to meet a wider applicable temperature range. However, the self-lubricating coatings provided by existing technologies are difficult to balance and take into account multiple performance requirements. Therefore, it is of great significance and value to develop a self-lubricating coating that can integrate low friction, wide temperature range and corrosion resistance. Summary of the Invention

[0005] This application provides a wide-temperature-range modified phosphate-based self-lubricating coating, its preparation method, and its application, in order to solve the problems mentioned in the background art.

[0006] In a first aspect, this application provides a method for preparing a wide-temperature-range modified phosphate-based self-lubricating coating, comprising the following steps: (1) Preparation of chromium aluminum phosphate adhesive: At a temperature of 90℃ and under stirring, CrO3 solution was added to polyphosphoric acid until the reaction system became clear and transparent. Al(OH)3 was then added in batches. After the addition was completed, stirring was continued for 2-3 hours. The mixture was then cooled to room temperature to obtain chromium aluminum phosphate adhesive. (2) Preparation of modified chromium aluminum phosphate adhesive: Heat the chromium aluminum phosphate adhesive to 110-120℃, add fumed silica in batches, continue stirring for 4-5h, then add B2O3 in batches, stir for 2-3h after the addition is complete, cool to room temperature, and continue stirring for 5-6h to obtain the modified chromium aluminum phosphate adhesive. (3) Preparation of wide temperature range modified phosphate-based self-lubricating coating: Mix modified chromium aluminum phosphate adhesive with silica sol, add deionized water after mixing evenly, stir to obtain a premix, add filler to the premix, continue stirring to obtain a wide temperature range modified phosphate-based self-lubricating coating. (4) Preparation of wide temperature range modified phosphate-based self-lubricating coating: The wide temperature range modified phosphate-based self-lubricating coating is sprayed onto the substrate surface to form a wide temperature range modified phosphate-based self-lubricating coating.

[0007] Optionally, in the preparation step of the chromium aluminum phosphate adhesive, the mass ratio of polyphosphoric acid to CrO3 solution is 12-13:1, and the ratio of chromium trioxide to water in the CrO3 solution is 1:5-2:5. The mass ratio of polyphosphoric acid to Al(OH)3 is 6-7:1.

[0008] Optionally, in the preparation step of the modified chromium aluminum phosphate adhesive, the mass ratio of polyphosphoric acid to fumed silica is 25-26:1, and the mass ratio of polyphosphoric acid to B2O3 is 29-30:1.

[0009] Optionally, in the preparation steps of the wide-temperature-range modified phosphate-based self-lubricating coating, the premix contains: The mass ratio of modified chromium aluminum phosphate adhesive to silica sol is 5:1; The mass ratio of the modified aluminum chromium phosphate adhesive and silica sol to deionized water is 1:2-3:5.

[0010] Optionally, the mass ratio of the premix to the filler is 1:2-3.

[0011] Optionally, the fillers include lubricating fillers, aggregates, and anti-corrosion fillers in a mass ratio of 5:4:2; The lubricating filler consists of WS2, h-BN and graphite in a mass ratio of 3:1:1, and the aggregate is glass powder. The anti-corrosion filler consists of aluminum tripolyphosphate and zinc phosphate in a mass ratio of 1:1.

[0012] Optionally, the particle size of the filler is 4-7 μm.

[0013] Optionally, the method for preparing the self-lubricating coating also includes: Preparation of polyphosphoric acid: Add phosphoric acid to a container, heat to 150-160℃, and stir for 2-3 hours. After the reaction is complete, cool to room temperature to obtain polyphosphoric acid.

[0014] Secondly, this application provides a wide-temperature-range modified phosphate-based self-lubricating coating, which is obtained by the above-described preparation method.

[0015] Thirdly, this application provides an application of a wide-temperature-range modified phosphate-based self-lubricating coating in the fields of wide-temperature-range bonded solid lubrication and corrosion protection.

[0016] The wide-temperature-range modified phosphate-based self-lubricating coating, its preparation method, and its application provided in this application realize the preparation of self-lubricating coatings and have the following advantages compared with the prior art: (1) In this application, chromium trioxide solution is first slowly added to polyphosphoric acid. CrO3, as an oxidant and chromium source, reacts with phosphoric acid to form chromate. After the addition of Al(OH)3, an aluminum phosphate complex is formed, which enhances the network crosslinking density and initially constructs a polymer network to synthesize chromium aluminum phosphate adhesive. By introducing fumed silica and boron oxide stepwise, the chromium aluminum phosphate adhesive is modified. The Si-OH on the SiO2 surface combines with phosphoric acid, water, and chromium aluminum ions in the adhesive through strong hydrogen bonding, forming a three-dimensional network structure around the particles and improving the thixotropic properties of the system. Boron ions in the B2O3 solution react with phosphate ions to form a mixed network of borophosphate or POB bonds with extremely high thermal stability. The structure of BPO4 is relatively stable and can significantly improve the high-temperature resistance of the adhesive. At the same time, by constructing a Si-O-Si network and a BOB structure and making it interpenetrate with the inorganic phosphate network, the density and oxidation resistance of the composite phosphate coating are further improved, inhibiting oxidation and structural deterioration under high-temperature conditions. By mixing modified chromium aluminum phosphate adhesive with silica sol and deionized water, then adding filler and stirring, a wide-temperature-range modified phosphate-based self-lubricating coating is obtained. Finally, by spraying the self-lubricating coating onto the substrate surface and sintering at high temperature, a wide-temperature-range modified phosphate-based self-lubricating coating is obtained.

[0017] (2) This application uses aluminum chromium phosphate as the base resin. By introducing fumed silica and B2O3 to synergistically modify the resin molecular structure, a more stable and dense composite network is constructed, which improves the temperature resistance and film quality of the resin after curing. At the same time, by compounding fillers, a wide-temperature-range modified phosphate-based self-lubricating coating with load-bearing, isolation and self-lubricating functions is formed. The resulting coating has a dense structure and stable performance. It not only has excellent oxidation resistance and corrosion resistance, but also maintains good lubrication and friction reduction effect in a wide temperature range from room temperature to 800℃, meeting the service requirements under high temperature and complex working conditions.

[0018] (3) This application combines various lubricating fillers with chromium aluminum phosphate base resin. Through the complementary effects of different lubricating phases in different temperature ranges, a stable and continuous lubrication effect is achieved in a wide temperature range, thereby further improving the friction reduction and wear resistance of the coating under complex service conditions. At the same time, anti-corrosion functional fillers are added for synergistic supplementation to ensure that the coating has good corrosion resistance. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a process diagram for preparing a wide-temperature-range modified phosphate-based self-lubricating coating provided in Embodiment 1 of this application; Figure 2 The friction curves and average friction coefficient diagrams of the wide-temperature-range modified phosphate-based self-lubricating coatings provided in Example 2 and Comparative Example 1 are shown. Figure 2 (a) is a friction curve of the self-lubricating coating provided in Example 2 and Comparative Example 1 at 300°C. Figure 2 (b) is a graph showing the average friction coefficient of the self-lubricating coatings provided in Example 2 and Comparative Example 1 at 300°C. Figure 2 (c) is the friction curve of the self-lubricating coating at 800°C provided in Example 2 and Comparative Example 1. Figure 2 (d) is a graph showing the average friction coefficient of the self-lubricating coatings provided in Example 2 and Comparative Example 1 at 800°C; Figure 3 The cross-sectional morphology of the self-lubricating coating obtained by sintering at 800°C in Example 2 is shown. Figure 4 The salt spray resistance diagram is shown for the wide temperature range modified phosphate-based self-lubricating coating provided in Example 2. Figure 5 The graphs show the adhesion performance of the wide-temperature-range modified phosphate-based self-lubricating coating provided in Example 2 under sintering treatment at different temperatures (300℃, 800℃). Figure 5 (a) is a test graph showing the adhesion performance of the self-lubricating coating provided in Example 2 under sintering treatment at 800°C. Figure 5 (b) is a test diagram of the adhesion performance of the self-lubricating coating provided in Example 2 under sintering treatment at 300°C; Figure 6 The XRD patterns of the self-lubricating coatings provided in Example 2 and Comparative Example 1 under sintering treatment at different temperatures (300℃, 600℃, 800℃) are shown below. Figure 6(a) shows the XRD patterns of the self-lubricating coating provided in Comparative Example 1 under sintering treatment at different temperatures (300℃, 600℃, 800℃). Figure 6 (b) shows the XRD patterns of the self-lubricating coating provided in Example 2 under sintering treatment at different temperatures (300°C, 600°C, 800°C). Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0022] like Figure 1 As shown, in a first aspect, this application provides a method for preparing a wide-temperature-range modified phosphate-based self-lubricating coating, comprising the following steps: (1) Preparation of chromium aluminum phosphate adhesive: At a temperature of 90℃ and under stirring, CrO3 solution was added to polyphosphoric acid until the reaction system became clear and transparent. Al(OH)3 was then added in batches. After the addition was completed, stirring was continued for 2-3 hours. The mixture was then cooled to room temperature to obtain chromium aluminum phosphate adhesive. (2) Preparation of modified chromium aluminum phosphate adhesive: Heat the chromium aluminum phosphate adhesive to 110-120℃, add fumed silica in batches, continue stirring for 4-5h, then add B2O3 in batches, stir for 2-3h after the addition is complete, cool to room temperature, and continue stirring for 5-6h to obtain the modified chromium aluminum phosphate adhesive. (3) Preparation of wide temperature range modified phosphate-based self-lubricating coating: The modified chromium aluminum phosphate adhesive is mixed with silica sol. After mixing evenly, deionized water is added and stirred to obtain a premix. Filler is added to the premix, stirring is continued, and ball milling is performed for 24 hours to obtain a wide temperature range modified phosphate-based self-lubricating coating. (4) Preparation of wide temperature range modified phosphate-based self-lubricating coating: The wide temperature range modified phosphate-based self-lubricating coating is sprayed onto the substrate surface to form a wide temperature range modified phosphate-based self-lubricating coating.

[0023] Specifically, in the preparation process of chromium aluminum phosphate adhesive, chromium trioxide (CrO3) solution is slowly added to polyphosphoric acid. CrO3 acts as an oxidant and chromium source, reacting with phosphoric acid to form chromates (mainly including CrO4). 2- or Cr2O7 2-The polyphosphoric acid (a chromate-like product) is simultaneously partially hydrolyzed to orthophosphoric acid, providing more phosphate ligands. The clear and transparent system indicates the formation of a homogeneous complex solution. After Al(OH)3 is added in batches (at least three batches), an acid-base neutralization reaction occurs, and Al... 3+ It combines with phosphate ions in polyphosphoric acid to form aluminum phosphate complexes, enhancing the network crosslinking density, initially constructing a polymer network, and promoting the growth of metal ions (Cr). 6+ Al 3+ Further coordination and condensation between chromium aluminum phosphate and polyphosphate occur. The POP bonds of polyphosphate partially break and crosslink with metal ions, forming a more stable three-dimensional prepolymer structure. Upon cooling to room temperature, the viscosity of the system increases, resulting in a uniform chromium aluminum phosphate adhesive. During the addition of CrO3 solution and aluminum hydroxide, the reaction system is allowed to become clear and transparent after each addition before further addition. Introducing CrO3 doping during synthesis enhances the strength of the phosphate molecular network structure, thereby effectively improving the temperature resistance and film-forming processability of the cured coating.

[0024] The purity of CrO3 and Al(OH)3 is ≥98%.

[0025] In the preparation of modified chromium aluminum phosphate adhesive, fumed silica and boron oxide are introduced stepwise to achieve the goals of strengthening and toughening, regulating rheology, improving heat resistance, and enhancing oxidation resistance and chemical stability. First, the chromium aluminum phosphate adhesive is heated to improve the fluidity of the base adhesive and reduce viscosity, facilitating the uniform dispersion of subsequent nanomaterials. Simultaneously, this temperature partially removes physically adsorbed water, increasing the system's activity, but remains below the main polycondensation reaction temperature to avoid excessively rapid curing.

[0026] The addition of fumed silica enhances the structural strength, wear resistance, and thermal stability of the adhesive, while also improving the coating's density. Fumed silica, with its high specific surface area and rich silanol content, is added in batches to prevent the "fish-eye" phenomenon caused by instantaneous agglomeration, ensuring uniform dispersion of silica particles within the chromium aluminum phosphate adhesive. The Si-OH groups on the SiO2 surface bind strongly with phosphoric acid, water, and chromium aluminum ions in the adhesive through hydrogen bonding, forming a three-dimensional network structure around the particles and significantly improving the system's thixotropy. Further batch addition of B2O3 solution allows boron ions to react with phosphate ions, forming a highly thermally stable borophosphate (such as BPO4) or POB-bonded mixed network. The relatively stable structure of BPO4 significantly improves the adhesive's high-temperature resistance. Simultaneously, constructing a Si-O-Si network and a BOB structure, and integrating them with the inorganic phosphate network to form an interpenetrating structure, further enhances the density and oxidation resistance of the composite phosphate coating, suppressing oxidation and structural degradation under high-temperature conditions.

[0027] The particle size of the fumed silica is 20 nm.

[0028] In the preparation of wide-temperature-range modified phosphate-based self-lubricating coatings, the addition of silica sol during subsequent curing allows the silica sol to form a silicon-oxygen (Si-O-Si) network through dehydration condensation. This network interpenetrates with the phosphate (POM, M=Cr,Al) network, forming a denser and stronger composite inorganic binder phase, significantly improving the coating's adhesion strength and cohesion. Deionized water is then added for dilution, precisely adjusting the coating's working viscosity to meet the requirements of the spraying process. Simultaneously, the solid content in the coating is controlled to ensure the final dry film thickness and density. The addition of fillers enables the formation of a protective film between the contact surfaces under frictional shearing, providing a lubricating effect.

[0029] The preparation process of the wide-temperature-range modified phosphate-based self-lubricating coating also includes: taking the workpiece to be coated (such as the nickel-based superalloy Inconel 718), sandblasting it at a pressure of 0.4 MPa until the surface is free of any contamination, increasing the surface roughness to Ra5-10 μm, improving the adhesion between the coating and the substrate, and cleaning it with anhydrous ethanol. Subsequently, the prepared wide-temperature-range modified phosphate-based self-lubricating coating is added to an air spray gun, the spraying pressure is adjusted to 0.2-0.4 MPa for surface spraying, and the spraying thickness is controlled at 20-30 μm. After spraying, the workpiece is placed at room temperature to air dry naturally for 6-8 hours, and then placed in a high-temperature sintering furnace. The temperature is raised from room temperature to 300℃ at a rate of 10℃ / min, and held at 300℃ for 30 minutes to complete the curing process of the coating. Then, the temperature is raised from 300℃ to 800℃ at a rate of 10℃ / min, and held at 800℃ for 2 hours to obtain a wide-temperature-range modified phosphate-based self-lubricating coating.

[0030] During the high-temperature sintering process, a continuous glaze layer gradually forms on the surface of the self-lubricating coating. This glaze layer acts as an isolation and load-bearing layer at the friction interface, significantly improving the high-temperature lubrication performance and oxidation resistance of the coating. Therefore, the structural stability of the modified phosphate resin and the synergistic effect of the filler system are key factors determining the overall performance of the composite coating. Regarding the resin system, this invention uses chromium aluminum phosphate as the base resin, introducing CrO3 doping during the synthesis process to enhance the strength of the phosphate molecular network structure, thereby effectively improving the temperature resistance and film-forming processability of the cured resin. Simultaneously, by constructing a Si-O-Si network and a BOB structure, and forming an interpenetrating structure with the inorganic phosphate network, the density and oxidation resistance of the composite phosphate coating are further improved, inhibiting oxidation and structural degradation under high-temperature conditions.

[0031] The above scheme facilitated the preparation of a wide-temperature-range modified phosphate-based self-lubricating coating. First, a chromium trioxide solution was slowly added to polyphosphoric acid. CrO3, acting as both an oxidant and a chromium source, reacted with phosphoric acid to generate chromate products. The addition of Al(OH)3 formed an aluminum phosphate complex, enhancing the network crosslinking density and initially constructing a polymer network to synthesize an aluminum chromium phosphate adhesive. The adhesive was further modified by stepwise introduction of fumed silica and boron oxide. The Si-OH groups on the SiO2 surface bonded strongly with phosphoric acid, water, and chromium / aluminum ions in the adhesive through hydrogen bonding, forming a three-dimensional network structure around the particles and improving the system's thixotropy. In the B2O3 solution, boron ions reacted with phosphate ions to form a highly thermally stable mixed network of borophosphate or POB bonds. The relatively stable structure of BPO4 significantly improved the adhesive's high-temperature resistance. Meanwhile, by constructing a Si-O-Si network and a BOB structure, and making them interpenetrate with the inorganic phosphate network, the density and oxidation resistance of the composite phosphate coating were further improved, inhibiting oxidation and structural degradation under high-temperature conditions. A wide-temperature-range modified phosphate-based self-lubricating coating was obtained by mixing modified chromium aluminum phosphate adhesive with silica sol and deionized water, adding fillers, and stirring. Finally, the self-lubricating coating was sprayed onto the substrate surface and sintered at high temperature to obtain a wide-temperature-range modified phosphate-based self-lubricating coating.

[0032] This application uses aluminum chromium phosphate as the base resin and synergistically modifies the resin molecular structure by introducing fumed silica and B2O3 to construct a more stable and dense composite network, thereby improving the temperature resistance and film quality of the cured resin. Simultaneously, by compounding fillers, a wide-temperature-range modified phosphate-based self-lubricating coating with load-bearing, isolation, and self-lubricating functions is formed. The resulting coating has a dense structure and stable performance, exhibiting not only excellent oxidation resistance and corrosion resistance but also maintaining good lubrication and friction reduction effects over a wide temperature range from room temperature to 800℃, meeting the service requirements under high-temperature and complex operating conditions.

[0033] Optionally, in the preparation step of the chromium aluminum phosphate adhesive, the mass ratio of polyphosphoric acid to CrO3 solution is 12-13:1, and the ratio of chromium trioxide to water in the CrO3 solution is 1:5-2:5. The mass ratio of polyphosphoric acid to Al(OH)3 is 6-7:1.

[0034] Optionally, in the preparation step of the modified chromium aluminum phosphate adhesive, the mass ratio of polyphosphoric acid to fumed silica is 25-26:1, and the mass ratio of polyphosphoric acid to B2O3 is 29-30:1.

[0035] Optionally, in the preparation steps of the wide-temperature-range modified phosphate-based self-lubricating coating, the premix contains: The mass ratio of modified chromium aluminum phosphate adhesive to silica sol is 5:1; The mass ratio of the modified aluminum chromium phosphate adhesive and silica sol to deionized water is 1:2-3:5.

[0036] Optionally, the mass ratio of the premix to the filler is 1:2-3.

[0037] Optionally, the fillers include lubricating fillers, aggregates, and anti-corrosion fillers in a mass ratio of 5:4:2; The lubricating filler consists of WS2, h-BN and graphite in a mass ratio of 3:1:1, and the aggregate is glass powder. The anti-corrosion filler consists of aluminum tripolyphosphate and zinc phosphate in a mass ratio of 1:1.

[0038] Optionally, the particle size of the filler is 4-7 μm.

[0039] Specifically, WS2 is a layered transition metal sulfide with a hexagonal crystal structure. The layers are bonded by strong covalent bonds within the layers and by weak van der Waals forces between the layers. Under frictional shear forces, WS2 layers readily slip, forming a low-shear-strength transfer film on the dual surface. WS2 exhibits higher thermal stability and oxidation initiation temperature, demonstrating excellent and stable lubrication performance in the mid-temperature range (room temperature to 500℃). h-BN has a higher oxidation resistance temperature (up to 900℃) and maintains good lubricity and chemical inertness even at high temperatures. In the mid-high to high-temperature range (above approximately 400℃), h-BN can replace WS2 and graphite as the primary lubricant, preventing coating failure at high temperatures. By specifically proportioning the components in the lubricating filler, a temperature gradient relay system for lubrication function is created, enabling the self-lubricating coating to cover a wide temperature range from room temperature to 800℃ or even higher.

[0040] Using glass powder as aggregate, during the subsequent sintering and curing stage, the glass powder softens and melts. The molten glass phase can: flow and fill the micropores formed after drying, greatly improving the coating's density and resistance to media penetration; simultaneously, it more firmly bonds the phosphate matrix, various filler particles, and the matrix surface together, significantly enhancing the coating's cohesive strength and adhesion to the matrix. Furthermore, the glass phase can alleviate internal stress caused by the mismatch in thermal expansion coefficients during sintering and cooling, reducing the tendency to crack. Corrosion-resistant fillers can provide chemical corrosion protection to metal substrates (such as steel and aluminum alloys), which is beneficial for the long-term service of the coating in corrosive environments such as humidity and salt spray.

[0041] Regarding the filler system, this application combines various lubricating fillers with chromium aluminum phosphate base resin. Through the complementary effects of different lubricating phases in different temperature ranges, a stable and continuous lubrication effect is achieved in a wide temperature range, thereby further improving the friction reduction and wear resistance of the coating under complex service conditions. At the same time, anti-corrosion functional fillers are added for synergistic supplementation to ensure that the coating has good corrosion resistance.

[0042] Optionally, the method for preparing the self-lubricating coating also includes: Preparation of polyphosphoric acid: Add phosphoric acid to a container, heat to 150-160℃, and stir for 2-3 hours. After the reaction is complete, cool to room temperature to obtain polyphosphoric acid.

[0043] Specifically, polyphosphoric acid is prepared by heating phosphoric acid to dehydrate and condense it, removing the structural water from the phosphoric acid molecules and promoting the linkage of phosphoric acid units. The reaction is stirred for 2-3 hours to ensure complete reaction and reach or approach the polymerization equilibrium state at that temperature, resulting in a stable viscosity and composition for the polyphosphoric acid. If the time is too short, polymerization will be incomplete; if the time is too long, the effect on increasing the degree of polymerization is limited and uneconomical.

[0044] Phosphoric acid was selected from analytical grade with a purity of 85%.

[0045] Secondly, this application provides a wide-temperature-range modified phosphate-based self-lubricating coating, which is obtained by the above-described preparation method.

[0046] Thirdly, this application provides an application of a wide-temperature-range modified phosphate-based self-lubricating coating in the fields of wide-temperature-range bonded solid lubrication and corrosion protection.

[0047] The following are embodiments and effect test examples of this application, further describing the technical solution and technical effects of the present invention. However, the scope of protection of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not depart from the concept of the present invention are within the scope of protection of the present invention. Furthermore, for those embodiments where specific technical operation steps or conditions are not specified, they are performed according to the techniques or conditions described in general literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0048] Example 1 A method for preparing a wide-temperature-range modified phosphate-based self-lubricating coating includes the following steps: (1) Preparation of chromium aluminum phosphate adhesive: Phosphoric acid was added to a container, heated to 150°C, and stirred for 3 hours. After the reaction was completed, it was cooled to room temperature to obtain polyphosphoric acid. At 90°C, under stirring, CrO3 solution was added to polyphosphoric acid until the reaction system was clear and transparent. Al(OH)3 was then added in batches. After the addition was completed, stirring was continued for 3 hours. After cooling to room temperature, chromium aluminum phosphate adhesive was obtained. The mass ratio of polyphosphoric acid to CrO3 solution was 12:1, the ratio of chromium trioxide to water in CrO3 solution was 1:5, and the mass ratio of polyphosphoric acid to Al(OH)3 was 6:1.

[0049] (2) Preparation of modified chromium aluminum phosphate adhesive: The chromium aluminum phosphate adhesive was heated to 110°C and fumed silica was added in batches. Stirring was continued for 5 hours, and then B2O3 was added in batches. After the addition was completed, the mixture was stirred for 3 hours, cooled to room temperature, and stirred for 6 hours to obtain the modified chromium aluminum phosphate adhesive. The mass ratio of polyphosphoric acid to fumed silica was 25:1, and the mass ratio of polyphosphoric acid to B2O3 was 29:1.

[0050] (3) Preparation of wide-temperature-range modified phosphate-based self-lubricating coating: Modified chromium aluminum phosphate adhesive was mixed with silica sol. After uniform mixing, deionized water was added and stirred to obtain a premix. Filler was added to the premix, and stirring was continued. The mixture was then ball-milled for 24 hours to obtain a wide-temperature-range modified phosphate-based self-lubricating coating. The mass ratio of modified chromium aluminum phosphate adhesive to silica sol was 5:1. The mass ratio of the sum of the masses of modified chromium aluminum phosphate adhesive and silica sol to the mass ratio of deionized water was 1:2. The silica sol was purchased from [unspecified source], model ZJN-30.

[0051] The mass ratio of the premix to the filler is 1:2. The filler includes lubricating filler, aggregate, and anti-corrosion filler in a mass ratio of 5:4:2. The lubricating filler includes WS2, h-BN, and graphite in a mass ratio of 3:1:1. The aggregate is glass powder. The anti-corrosion filler includes aluminum tripolyphosphate and zinc phosphate in a mass ratio of 1:1. The particle size of the filler is 4-6 μm.

[0052] (4) Preparation of wide-temperature-range modified phosphate-based self-lubricating coating: Take the Inconel 718 nickel-based high-temperature alloy workpiece to be sprayed and sandblast it under a pressure of 0.4 MPa until the surface is free of any contamination. Then clean it with anhydrous ethanol. Subsequently, add the prepared wide-temperature-range modified phosphate-based self-lubricating coating into the air spray gun, adjust the spraying pressure to 0.2 MPa and spray the surface until the surface roughness is Ra5-7 μm and the spraying thickness is controlled at 20-25 μm. After spraying, place the workpiece in a room temperature air dryer for 6 hours, and then place it in a high-temperature sintering furnace. The room temperature is raised to 300℃ at a rate of 10℃ / min, and the temperature is held at 300℃ for 30 minutes to complete the curing treatment of the coating. Then the temperature is raised from 300℃ to 800℃ at a rate of 10℃ / min and held at 800℃ for 2 hours to obtain the wide-temperature-range modified phosphate-based self-lubricating coating. Example 2

[0053] A method for preparing a wide-temperature-range modified phosphate-based self-lubricating coating includes the following steps: (1) Preparation of chromium aluminum phosphate adhesive: Phosphoric acid was added to a container, heated to 155℃, and stirred for 2.5 h. After the reaction was completed, it was cooled to room temperature to obtain polyphosphoric acid. At 90℃ and under stirring, CrO3 solution was added to polyphosphoric acid until the reaction system was clear and transparent. Al(OH)3 was then added in batches. After the addition was completed, stirring was continued for 2.5 h. After cooling to room temperature, chromium aluminum phosphate adhesive was obtained. The mass ratio of polyphosphoric acid to CrO3 solution was 12.5:1, the ratio of chromium trioxide to water in CrO3 solution was 1.5:5, and the mass ratio of polyphosphoric acid to Al(OH)3 was 6.5:1.

[0054] (2) Preparation of modified chromium aluminum phosphate adhesive: The chromium aluminum phosphate adhesive was heated to 115°C and fumed silica was added in batches. Stirring was continued for 4 hours, and then B2O3 was added in batches. After the addition was completed, the mixture was stirred for 2 hours, cooled to room temperature, and stirred for 5 hours to obtain the modified chromium aluminum phosphate adhesive. The mass ratio of polyphosphoric acid to fumed silica was 25.5:1, and the mass ratio of polyphosphoric acid to B2O3 was 29:1.

[0055] (3) Preparation of wide-temperature-range modified phosphate-based self-lubricating coating: Modified chromium aluminum phosphate adhesive was mixed with silica sol. After uniform mixing, deionized water was added and stirred to obtain a premix. Filler was added to the premix, and stirring was continued. The mixture was then ball-milled for 24 hours to obtain a wide-temperature-range modified phosphate-based self-lubricating coating. The mass ratio of modified chromium aluminum phosphate adhesive to silica sol was 5:1. The mass ratio of the sum of the masses of modified chromium aluminum phosphate adhesive and silica sol to the mass ratio of deionized water was 3:5. The silica sol was purchased from [unspecified source], model ZJN-30.

[0056] The mass ratio of the premix to the filler is 1:3. The filler includes lubricating filler, aggregate, and anti-corrosion filler in a mass ratio of 5:4:2. The lubricating filler includes WS2, h-BN, and graphite in a mass ratio of 3:1:1. The aggregate is glass powder. The anti-corrosion filler includes aluminum tripolyphosphate and zinc phosphate in a mass ratio of 1:1. The particle size of the filler is 4-7 μm.

[0057] (4) Preparation of wide-temperature-range modified phosphate-based self-lubricating coating: Take the Inconel 718 nickel-based high-temperature alloy workpiece to be sprayed, and perform sandblasting treatment under a pressure of 0.4 MPa, followed by cleaning with anhydrous ethanol. Then, add the prepared wide-temperature-range modified phosphate-based self-lubricating coating into the air spray gun, adjust the spraying pressure to 0.3 MPa for surface spraying, until the surface roughness is Ra6-8 μm, and the spraying thickness is controlled at 25-30 μm. After spraying, place the workpiece in a room temperature air dryer for 8 hours, and then place it in a high-temperature sintering furnace. The room temperature is raised to 300℃ at a heating rate of 10℃ / min, and held at 300℃ for 30 minutes to complete the curing treatment of the coating. Then, the temperature is raised from 300℃ to 800℃ at a heating rate of 10℃ / min, and held at 800℃ for 2 hours to obtain the wide-temperature-range modified phosphate-based self-lubricating coating. Example 3

[0058] A method for preparing a wide-temperature-range modified phosphate-based self-lubricating coating includes the following steps: (1) Preparation of chromium aluminum phosphate adhesive: Phosphoric acid was added to a container, heated to 160℃, and stirred for 2 hours. After the reaction was completed, it was cooled to room temperature to obtain polyphosphoric acid. At 90℃ and under stirring, CrO3 solution was added to polyphosphoric acid until the reaction system was clear and transparent. Al(OH)3 was then added in batches. After the addition was completed, stirring was continued for 2 hours. After cooling to room temperature, chromium aluminum phosphate adhesive was obtained. The mass ratio of polyphosphoric acid to CrO3 solution was 13:1, the ratio of chromium trioxide to water in CrO3 solution was 2:5, and the mass ratio of polyphosphoric acid to Al(OH)3 was 7:1.

[0059] (2) Preparation of modified chromium aluminum phosphate adhesive: The chromium aluminum phosphate adhesive was heated to 120°C and fumed silica was added in batches. Stirring was continued for 5 hours, and then B2O3 was added in batches. After the addition was completed, the mixture was stirred for 3 hours, cooled to room temperature, and stirred for 6 hours to obtain the modified chromium aluminum phosphate adhesive. The mass ratio of polyphosphoric acid to fumed silica was 26:1, and the mass ratio of polyphosphoric acid to B2O3 was 30:1.

[0060] (3) Preparation of wide-temperature-range modified phosphate-based self-lubricating coating: Modified chromium aluminum phosphate adhesive was mixed with silica sol. After uniform mixing, deionized water was added and stirred to obtain a premix. Filler was added to the premix, and stirring was continued. The mixture was then ball-milled for 24 hours to obtain a wide-temperature-range modified phosphate-based self-lubricating coating. The mass ratio of modified chromium aluminum phosphate adhesive to silica sol was 5:1. The mass ratio of the sum of the masses of modified chromium aluminum phosphate adhesive and silica sol to the mass ratio of deionized water was 3:5. The silica sol was purchased from [unspecified source], model ZJN-30.

[0061] The mass ratio of the premix to the filler is 1:3. The filler includes lubricating filler, aggregate, and anti-corrosion filler in a mass ratio of 5:4:2. The lubricating filler includes WS2, h-BN, and graphite in a mass ratio of 3:1:1. The aggregate is glass powder. The anti-corrosion filler includes aluminum tripolyphosphate and zinc phosphate in a mass ratio of 1:1. The particle size of the filler is 5-7 μm.

[0062] (4) Preparation of wide-temperature-range modified phosphate-based self-lubricating coating: Take the Inconel 718 nickel-based high-temperature alloy workpiece to be sprayed, and perform sandblasting treatment under a pressure of 0.4 MPa, followed by cleaning with anhydrous ethanol. Then, add the prepared wide-temperature-range modified phosphate-based self-lubricating coating into the air spray gun, adjust the spraying pressure to 0.4 MPa for surface spraying, until the surface roughness is Ra 8-10 μm, and the spraying thickness is controlled at 25-30 μm. After spraying, place the workpiece in a room temperature air dryer for 8 hours, and then place it in a high-temperature sintering furnace. The room temperature is raised to 300℃ at a heating rate of 10℃ / min, and held at 300℃ for 30 minutes to complete the curing treatment of the coating. Then, the temperature is raised from 300℃ to 800℃ at a heating rate of 10℃ / min, and held at 800℃ for 2 hours to obtain the wide-temperature-range modified phosphate-based self-lubricating coating.

[0063] Comparative Example 1 A method for preparing a wide-temperature-range modified phosphate-based self-lubricating coating includes the following steps: The difference from Example 2 is that: (2) No modification is made to the chromium aluminum phosphate adhesive.

[0064] Experimental Example 1 Wide-temperature-range modified phosphate-based self-lubricating coatings were successfully synthesized in Examples 1-3. Taking Example 2 as an example, the tribological properties of the self-lubricating coatings provided in Example 2 and Comparative Example 1 under sintering treatment at different temperatures (300℃ and 800℃) were tested.

[0065] Test conditions: ball-disc contact, reciprocating wear, loads of 2N and 5N, frequency of 2Hz, amplitude of 8mm, paired with a 6mm Al2O3 ball. The friction coefficient curve over time and the average friction coefficient were obtained, as shown below. Figure 2 As shown.

[0066] Figure 2 The friction curves and average friction coefficient diagrams of the wide-temperature-range modified phosphate-based self-lubricating coatings provided in Example 2 and Comparative Example 1 are shown. Figure 2 (a) is a friction curve of the self-lubricating coating provided in Example 2 and Comparative Example 1 at 300°C. Figure 2 (b) is a graph showing the average friction coefficient of the self-lubricating coatings provided in Example 2 and Comparative Example 1 at 300°C. Figure 2(c) is the friction curve of the self-lubricating coating at 800°C provided in Example 2 and Comparative Example 1. Figure 2 (d) is the average friction coefficient diagram of the self-lubricating coating at 800°C provided in Example 2 and Comparative Example 1.

[0067] observe Figure 2 In (a), the average coefficient of friction (COF) of Comparative Example 1-300°C-2N and Example 2-300°C-2N were 0.187 and 0.196, respectively, with little difference. Comparative Example 1-300°C-5N exhibited the highest COF (0.275) under higher loads, while the modified coating provided in Example 2 had the lowest COF under the same conditions, at only 0.161, showing a significant friction reduction effect, reducing friction by approximately 41.45%. Figure 2 (c) Figure 2 (d) represents the frictional behavior of the coating at 800℃. The COF of Comparative Example 1-800℃-2N shows a continuous upward trend, and increases sharply after 23 minutes of testing, with an average friction coefficient of 0.3. The average COF of Comparative Example 1-800℃-5N is as high as 1.8, indicating that its wear resistance decreases and the coating hardness decreases after high-temperature sintering. In contrast, the wide-temperature-range modified phosphate-based self-lubricating coatings 2N and 5N provided in Example 2 of this application exhibit excellent friction-reducing properties at high temperatures, with average COFs of 0.13 and 0.12, respectively, representing reductions of approximately 56.7% and 93.3%, indicating that the modified adhesive significantly improves the lubrication effect and stability of the coating after high-temperature sintering.

[0068] Experimental Example 2 The cross-sectional morphology of the coating obtained by sintering at 800°C in Example 2 was examined by scanning electron microscopy (SEM), and the results are as follows. Figure 3 As shown. Figure 3 This is a cross-sectional morphology diagram of the self-lubricating coating obtained by sintering at 800°C as provided in Example 2.

[0069] Figure 3 It is evident that the coating consists of a surface glaze layer (upper layer), a bonding layer (middle layer), and a substrate (lower layer). The surface glaze layer exhibits a relatively dense structure, effectively preventing external friction and chemical erosion, and effectively reducing the coefficient of friction while enhancing lubrication performance. Simultaneously, the bonding layer is tightly bonded to both the upper and lower layers, with a clear and continuous interface; the internal structure of the coating is dense, with no obvious pores, cracks, or other defects observed.

[0070] Experimental Example 3 The salt spray resistance of the wide-temperature-range modified phosphate-based self-lubricating coating provided in Example 2 was tested.

[0071] The salt spray test conditions were as follows: Samples were placed in a salt spray chamber at 47°C, using an intermittent spraying method with a 5 wt% neutral NaCl solution as the spray medium. Each spray session lasted 12 hours. During the test, the samples were placed on a support with the test surface facing upwards at approximately a 30° angle to reduce salt accumulation on the surface. Different salt spray exposure durations were used to evaluate the corrosion resistance of the coating. After the corrosion test, the sample surface was first gently rinsed with clean distilled water to remove salt deposits, followed by further cleaning with anhydrous ethanol to ensure complete removal of residues. The samples were then allowed to air dry under ventilated conditions, and their surface morphology was observed, with a focus on checking for rust marks, to evaluate the coating's corrosion resistance. The results are as follows: Figure 4 As shown.

[0072] Figure 4 This is a diagram showing the salt spray resistance of the wide-temperature-range modified phosphate-based self-lubricating coating provided in Example 2. Figure 4 The macroscopic appearance evolution of the coating under different salt spray corrosion times (0-3624h) is shown. It can be clearly seen that as the corrosion time increases, the coating surface gradually changes from being initially smooth and bright to becoming darker and duller, but no obvious rust spots appear, indicating that the coating still maintains good corrosion resistance in long-term salt spray environment.

[0073] Experiment Example 4 The adhesion properties of the wide-temperature-range modified phosphate-based self-lubricating coating provided in Example 2 were tested under sintering treatment at different temperatures (300℃, 800℃).

[0074] Adhesion performance test conditions: Adhesion strength was characterized using a fully automated scribing method tester (radius of gyration: R=5.25mm, scribing length: 80mm, scribing needle: tip radius (0.05±0.01)mm, included angle 25°, scribing needle speed: approximately (80~100) rpm). The sample provided in Example 2 was mounted on a rotary table with a normal load of 500g. The results are as follows: Figure 5 As shown.

[0075] Figure 5 The graphs show the adhesion performance of the wide-temperature-range modified phosphate-based self-lubricating coating provided in Example 2 under sintering treatment at different temperatures (300℃, 800℃). Figure 5 (a) is a test graph showing the adhesion performance of the self-lubricating coating provided in Example 2 under sintering treatment at 800°C. Figure 5 (b) is a test diagram of the adhesion performance of the self-lubricating coating provided in Example 2 under sintering treatment at 300°C.

[0076] like Figure 5As shown in (a), after the self-lubricating coating provided in Example 2 was treated at 800°C, no obvious peeling, lifting or coating breakage was observed at the edge of the scratch. The scratch width reached 101.19-190.43 μm, indicating that the coating had good adhesion performance after high temperature. Figure 5 (b) Example 2 shows that the self-lubricating coating provided in this application has neat scratch edges at 300°C, with no obvious coating peeling, relatively small scratch widths, clear and complete scratch areas, and dense and continuous bonding areas, reflecting good bonding between the coating and the substrate. This indicates that the wide-temperature-range modified phosphate-based self-lubricating coating provided in this application has excellent adhesion performance on the substrate surface and can have good high-temperature stability in a wide temperature range from room temperature to 800°C, which is beneficial for the coating to serve in the self-lubricating and anti-corrosion conditions of the substrate at high temperatures.

[0077] Experimental Example 5 X-ray diffraction (XRD) tests were performed on the self-lubricating coatings provided in Example 2 and Comparative Example 1 under sintering treatment at different temperatures (300℃, 600℃, 800℃), and the results are as follows. Figure 6 As shown.

[0078] Figure 6 The XRD patterns of the self-lubricating coatings provided in Example 2 and Comparative Example 1 under sintering treatment at different temperatures (300℃, 600℃, 800℃) are shown below. Figure 6 (a) shows the XRD patterns of the self-lubricating coating provided in Comparative Example 1 under sintering treatment at different temperatures (300℃, 600℃, 800℃). Figure 6 (b) shows the XRD patterns of the self-lubricating coating provided in Example 2 under sintering treatment at different temperatures (300°C, 600°C, 800°C).

[0079] observe Figure 6As can be seen from (b), the diffraction peaks of the self-lubricating coating provided in Example 2 mainly correspond to the precursor Al(H2PO4)3 in the dry state. With the increase of heat treatment temperature, Al(H2PO4)3 gradually decomposes and undergoes crystallization transformation, forming a series of thermally stable crystalline phases, such as AlPO4 and Al4P2O9. Under the heat treatment condition of 600℃, high-temperature stable phases such as BPO4 and Si2P2O7 appear, indicating that the introduced boron source and silicon source participate in the synergistic reaction of the phosphate framework, effectively promoting the formation of a three-dimensional multiphase network structure, thereby enhancing the structural density and thermal stability of the coating. Among them, BPO4 belongs to the quartz tetrahedral framework, which is composed of BO4 and PO4 tetrahedra connected by sharing vertices to form a stable three-dimensional network structure, giving the coating excellent thermal shock resistance and chemical corrosion resistance. Si₂P₂O₇ belongs to the monoclinic crystal system. Its crystal structure consists of chain-like or layered structures formed by SiO₄ and PO₄ tetrahedra connected by P–O–P bridging oxygen atoms. This structure can effectively fill microcracks and pores in the coating at high temperatures, enhancing the overall integrity of the coating structure and helping to reduce thermal stress concentration and improve thermal shock resistance. As the temperature rises above 600℃, the XRD diffraction peak intensity significantly increases, indicating an increased degree of crystallinity. However, a certain proportion of amorphous phase still exists in the coating system, providing the possibility for the coating to maintain a certain degree of flexibility and interfacial adhesion. In contrast, Figure 6 The unmodified phosphate-based coating shown in (a) exhibits a relatively simple evolution behavior under the same conditions. In its dry room temperature state, it is predominantly Al(H2PO4)3, and after heat treatment to 600℃ and 800℃, it only transforms into small amounts of AlPO4 and Cr(PO3)3, lacking a multiphase synergistic reaction process. Although the increased heat treatment temperature brings about some crystallization, the overall crystalline phase variety is limited, lacking effective structural complementarity and network support, thus restricting its comprehensive properties such as thermal stability, density, and durability.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a wide-temperature-range modified phosphate-based self-lubricating coating, characterized in that, Includes the following steps: (1) Preparation of chromium aluminum phosphate adhesive: At a temperature of 90℃ and under stirring, CrO3 solution was added to polyphosphoric acid until the reaction system became clear and transparent. Al(OH)3 was then added in batches. After the addition was completed, stirring was continued for 2-3 hours. The mixture was then cooled to room temperature to obtain the chromium aluminum phosphate adhesive. (2) Preparation of modified chromium aluminum phosphate adhesive: The chromium aluminum phosphate adhesive is heated to 110-120℃, and fumed silica is added in batches. Stirring is continued for 4-5 hours, and B2O3 is added in batches. After the addition is completed, stirring is continued for 2-3 hours, cooled to room temperature, and stirred for 5-6 hours to obtain the modified chromium aluminum phosphate adhesive. (3) Preparation of wide temperature range modified phosphate-based self-lubricating coating: The modified chromium aluminum phosphate adhesive is mixed with silica sol. After the mixture is evenly mixed, deionized water is added and stirred to obtain a premix. Filler is added to the premix and stirring is continued to obtain the wide temperature range modified phosphate-based self-lubricating coating. (4) Preparation of wide temperature range modified phosphate-based self-lubricating coating: The wide temperature range modified phosphate-based self-lubricating coating is sprayed onto the substrate surface to form the wide temperature range modified phosphate-based self-lubricating coating.

2. The method for preparing the wide-temperature-range modified phosphate-based self-lubricating coating according to claim 1, characterized in that, In the preparation step of the chromium aluminum phosphate adhesive, the mass ratio of polyphosphoric acid to the CrO3 solution is 12-13:1, and the ratio of chromium trioxide to water in the CrO3 solution is 1:5-2:

5. The mass ratio of the polyphosphoric acid to the Al(OH)3 is 6-7:

1.

3. The method for preparing the wide-temperature-range modified phosphate-based self-lubricating coating according to claim 1, characterized in that, In the preparation steps of the modified chromium aluminum phosphate adhesive, the mass ratio of polyphosphoric acid to fumed silica is 25-26:1, and the mass ratio of polyphosphoric acid to B2O3 is 29-30:

1.

4. The method for preparing the wide-temperature-range modified phosphate-based self-lubricating coating according to claim 1, characterized in that, In the preparation steps of the wide-temperature-range modified phosphate-based self-lubricating coating, the premix contains: The mass ratio of the modified chromium aluminum phosphate adhesive to the silica sol is 5:1; The mass ratio of the modified aluminum chromium phosphate adhesive and the silica sol to the deionized water is 1:2-3:

5.

5. The method for preparing the wide-temperature-range modified phosphate-based self-lubricating coating according to claim 1, characterized in that, The mass ratio of the premix to the filler is 1:2-3.

6. The method for preparing the wide-temperature-range modified phosphate-based self-lubricating coating according to claim 1, characterized in that, The filler includes lubricating filler, aggregate, and anti-corrosion filler in a mass ratio of 5:4:2; The lubricating filler comprises WS2, h-BN and graphite in a mass ratio of 3:1:1, the aggregate is glass powder, and the anti-corrosion filler comprises aluminum tripolyphosphate and zinc phosphate in a mass ratio of 1:

1.

7. The method for preparing the wide-temperature-range modified phosphate-based self-lubricating coating according to claim 1, characterized in that, The particle size of the filler is 4-7 μm.

8. The method for preparing the wide-temperature-range modified phosphate-based self-lubricating coating according to claim 1, characterized in that, The method for preparing the self-lubricating coating further includes: Preparation of the polyphosphoric acid: Phosphoric acid is added to a container, heated to 150-160℃, and stirred for 2-3 hours. After the reaction is completed, it is cooled to room temperature to obtain the polyphosphoric acid.

9. A wide-temperature-range modified phosphate-based self-lubricating coating, characterized in that, It is obtained by the preparation method described in any one of claims 1-8.

10. The application of the wide-temperature-range modified phosphate-based self-lubricating coating as described in claim 9 in the fields of wide-temperature-range bonded solid lubrication and corrosion protection.

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