Silane-modified aluminum chromate phosphate-based lubricating coating, preparation method thereof, formed lubricating coating and preparation method of lubricating coating

Abstract

The present application provides a lubricating coating based on silane-modified aluminum chromate phosphate, a preparation method thereof, a formed lubricating coating, and a preparation method of the lubricating coating. The lubricating coating comprises the following components: a lubricant, which includes 5-10% of metal sulfide, 5-10% of boron nitride, and 5-15% of graphite; a binder, which is 11-25% of a silane-modified aluminum chromate phosphate binder; 1-5% of an antioxidant; a toughening and anti-wear agent, which includes 5-10% of an anti-wear agent and 5-15% of an anti-wear filler, and the anti-wear filler is a metal oxide. The lubricating coating further comprises pyrroloquinoline quinone and aluminum dihydroxyglycinate, and the weight ratio of pyrroloquinoline quinone, aluminum dihydroxyglycinate to the lubricant is 0.5-1:0.1-0.2:1. The lubricating coating is formed by coating the lubricating coating on a metal surface and then curing it by heating. The lubricating coating of the present application can significantly improve the friction reduction and anti-wear performance of the metal surface in the wide temperature range of 20-600 °C.

Description

Technical Field

[0001] This application relates to the field of solid lubrication technology, and particularly to a lubricating coating based on silane-modified aluminum chromate phosphate, a preparation method thereof, a formed lubricating coating, and a preparation method of the lubricating coating. Background Art

[0002] Fasteners and sliding components under high-temperature conditions, such as the rudder bearings and control device surface frictions seals of space shuttles, the seals of gas turbine blades and casings, many shaft-like components of various engines such as those in aerospace and marine vessels, and the weapon launch process, all involve the problem of ultra-high-temperature lubrication adhesion. At this temperature stage, grease lubricants have failed, and only solid lubrication can be used. Solid lubricating coatings can be applied to almost all friction components without changing the design and size of the parts, which is one of the current research focuses. When used in parts such as engines and blades, they are necessarily subjected to large temperature fluctuations; during the start-up stage, the temperature is normal temperature, while during the normal operation stage, the temperature is relatively high; therefore, high-temperature solid lubricating coatings will inevitably develop towards a wide temperature range, higher temperature, lower overall friction coefficient, and lower wear rate.

[0003] Bonded lubricating coatings have become the most suitable lubricating coatings for surface use among many surface protection technologies due to their excellent comprehensive performance, high batch coating efficiency, and low cost. Generally, organic resin adhesives or silicate resin adhesives are used, such as phenolic resin, silicone resin, polyimide resin, etc., which have certain high-temperature resistance. However, when the temperature exceeds 400 °C, the resin will decompose. Therefore, its temperature resistance is limited. Heat-resistant coatings with inorganic silicate as the binder have poor adhesion, impact resistance, water and oil resistance, and the long-term use temperature is not higher than 500 °C. Inorganic phosphate binders bond well with metals at high temperatures, have a low curing temperature in the atmosphere, and the coatings on metal substrates do not peel off after repeated thermal shocks, and can be considered an ideal binder for solid lubricating coatings.

[0004] However, current domestic solid lubricating coatings, although they may have relatively high temperature resistance and good lubrication and protection effects under their respective working conditions, due to the different lubricating materials used, there are differences in their oxidation resistance temperatures, and the curing conditions of the binders used are different. Single high-temperature lubricating coatings cannot be universal. In other temperature ranges, the friction coefficient is relatively large and the wear rate is relatively high, and there is still a large gap compared with foreign similar products, which has become a "bottleneck" problem for high-end equipment in our country. Therefore, it is of great significance to develop high-temperature lubricating coatings with excellent friction reduction, wear resistance, and oxidation resistance in a wide temperature range. Summary of the Invention

[0005] The present application provides a lubricating coating based on silane-modified aluminum chromate phosphate, a preparation method thereof, a formed lubricating coating, and a preparation method of the lubricating coating, so as to solve the above problems mentioned in the background art.

[0006] The present application provides a lubricating coating based on silane-modified aluminum chromate phosphate, and the lubricating coating comprises components in the following weight percentages:

[0007] Lubricant, the lubricant comprises 5-10% of metal sulfide, 5-10% of boron nitride and 5-15% of graphite, and the metal sulfide is molybdenum disulfide or tungsten disulfide.

[0008] Binder 11-25%, and the binder is a silane-modified aluminum chromate phosphate binder.

[0009] Antioxidant 1-5%, and the antioxidant is a rare earth fluoride, including: cerium trifluoride or lanthanum trifluoride.

[0010] Toughening and anti-wear agent, the toughening and anti-wear agent comprises 5-10% of anti-wear agent and 5-15% of anti-wear filler, the anti-wear agent comprises one or more of corundum, glass powder and glass fiber powder; the anti-wear filler is a metal oxide, and the metal oxide is one or more of aluminum oxide, chromium oxide, titanium oxide and silicon oxide.

[0011] The lubricating coating further comprises pyrroloquinoline quinone and aluminum dihydroxyglycinate, and the weight ratio of pyrroloquinoline quinone, aluminum dihydroxyglycinate to the lubricant is 0.5-1:0.1-0.2:1;

[0012] The balance is water.

[0013] Optionally, the graphite is colloidal graphite, the particle size of the graphite ≤5μm, and the particle sizes of the metal sulfide, boron nitride, rare earth fluoride and metal oxide are all ≤10μm.

[0014] The particle size of the anti-wear agent is 40-2500 mesh.

[0015] A preparation method of a lubricating coating based on silane-modified aluminum chromate phosphate, and the preparation method of the lubricating coating comprises the following steps:

[0016] (1) Preparation of solid dispersion slurry: Put the weighed lubricant, antioxidant and toughening and anti-wear agent into a ball mill tank, and also add pyrroloquinoline quinone and aluminum dihydroxyglycinate to the ball mill tank, add water to make it into a paste, and ball mill for 12-48h to obtain a solid dispersion slurry.

[0017] (2) Preparation of lubricating coating to be dispersed: Mix the ground solid dispersion slurry with a silane-modified aluminum chromate phosphate binder, and add water until the solid content is 30-40% to obtain a lubricating coating to be dispersed.

[0018] (3)Preparation of lubricating coating: Disperse the prepared lubricating coating to be dispersed on a high-speed disperser, and disperse it for 10 min under the condition of a rotation speed of 5000 - 7000 r / min to obtain the lubricating coating.

[0019] Optionally, the preparation method of the silane-modified aluminum chromate phosphate binder is as follows:

[0020] (1)Dilute phosphoric acid with deionized water to a phosphoric acid aqueous solution with a mass fraction of 60%, add chromium trioxide and stir until completely dissolved, then heat up to 80 - 85 °C.

[0021] (2)Add aluminum hydroxide in batches. After the aluminum hydroxide is completely dissolved, control the reaction temperature at 100 - 125 °C and react for 1 - 3 h.

[0022] (3)Add organic amine, cool down to 35 - 55 °C, add silane prepolymer, continue to react for 1 - 5 h, and then naturally cool to room temperature to obtain the silane-modified aluminum chromate phosphate binder, and adjust the solid content of the silane-modified aluminum chromate phosphate binder to 60 - 65% with deionized water for standby.

[0023] Optionally, the molar ratio of aluminum hydroxide to phosphoric acid is 1 - 1.4:3; the molar ratio of aluminum hydroxide to chromium trioxide is 2 - 4:1.

[0024] Optionally, the dosage of the organic amine is 2 - 10% of the mass of the silane-modified aluminum chromate phosphate binder, and the dosage of the silane prepolymer is 2 - 20% of the mass of the silane-modified aluminum chromate phosphate binder.

[0025] Optionally, the organic amine includes at least one of triethylamine, triethanolamine, ethylenediamine, and hexamethylenetetramine.

[0026] Optionally, the preparation method of the silane prepolymer is as follows:

[0027] Add deionized water to the siloxane and stir to mix, then dropwise add hydrochloric acid with a concentration of 0.5 mol / L for hydrolysis reaction for 0.5 - 1 h, heat up to 55 - 75 °C, continue to react for 3 - 8 h, and then naturally cool to room temperature, and remove the excess solvent to obtain the silane prepolymer. The molar ratio of siloxane to deionized water is 2 - 3:1.

[0028] The addition amount of hydrochloric acid is 0.1% of the total weight of the siloxane and deionized water.

[0029] Optionally, the siloxane includes one or more of methyltrimethoxysilane, methyldimethoxysilane, aminopropyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane.

[0030] A lubricating coating based on silane-modified aluminum chromate phosphate, which is formed by coating the lubricating coating on the metal surface and then heating and curing.

[0031] A preparation method of a lubricating coating based on silane-modified chromic phosphate aluminate. The method includes coating a lubricating paint on a metal surface using a spray gun and then heating and curing to obtain a solid lubricating coating.

[0032] The curing conditions are: first curing at 120 - 150 °C for 2 h, and then curing at 305 - 315 °C for 1 h.

[0033] The lubricating paint based on silane-modified chromic phosphate aluminate, the preparation method, the formed lubricating coating and the preparation method of the lubricating coating provided by this application improve the anti-friction and anti-wear performance of the lubricating coating on the metal surface in a wide temperature range of 20 - 600 °C. Compared with the prior art, it has the following beneficial effects:

[0034] (1) By using acid chromic phosphate aluminate and modifying the phosphate with a silane prepolymer, introducing a Si-O-P structure into the P-O-P network of the phosphate structure to obtain a silane-modified chromic phosphate aluminate binder, while enhancing the toughness of the binder, it also improves the impact resistance of the coating, improves the interfacial bonding between the binder and the lubricant, effectively covers the structural defects of the lubricant, improves the bonding force between the coating and the substrate surface, and also improves the anti-friction and anti-wear performance of the coating.

[0035] (2) By using a composite of metal sulfide, boron nitride and graphite as the lubricant, and taking advantage of the good slip ability between the lamellae of the two-dimensional layered structures of boron nitride and graphite, during the friction process, it is easy for the layers to slide between each other, thus reducing the friction coefficient between the metal surface and the friction pair and having an anti-friction effect. The active element sulfur in the metal sulfide can have a strong adsorption effect on the metal surface, enhancing the adhesion ability between the lubricating coating and the metal surface, so that the lubricating coating is difficult to be damaged during the friction process. By using a toughening and anti-wear agent to improve the strength of the lubricating coating, the wear resistance of the coating is further improved. Moreover, the lubricant, the silane-modified chromic phosphate aluminate binder, the toughening and anti-wear agent and the antioxidant act synergistically to form a film on the metal surface. By improving the strength of the lubricating coating, the wear rate of the lubricating coating is reduced, by improving the flexibility and impact strength of the lubricating coating, the wear resistance, the continuity of the lubricating film and the pressure-bearing capacity of the lubricating coating are improved, and by improving the antioxidant property of the lubricating coating, the temperature resistance of the lubricating coating is improved, enabling the lubricating coating to be applied to metal parts under wide temperature working conditions, and thus generally improving the anti-friction and anti-wear performance of the lubricating coating.

[0036] (2) By adding pyrroloquinoline quinone and aluminum glycinate into the lubricating coating, the carboxyl groups contained in pyrroloquinoline quinone can not only react with the carboxyl groups in aluminum glycinate to form ester compounds. At the same time, both pyrroloquinoline quinone and aluminum glycinate contain N elements, and the N element can undergo p-d back donation coordination with the outer electrons generated on the metal surface. Therefore, the lubricating coating containing pyrroloquinoline quinone and aluminum glycinate can improve the bonding force between the lubricating coating and the metal surface, making the bearing capacity of the lubricating coating stronger during the friction process. Moreover, the active groups in pyrroloquinoline quinone and aluminum glycinate can also interact with the silane-modified aluminum chromate phosphate binder molecules, improving the dispersibility of lubricants, antioxidants, and toughening and anti-wear agents in the binder, enhancing the uniformity of the lubricating coating, and further improving the lubrication effect of the lubricating coating. Description of the Drawings

[0037] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 Schematic diagram of the microstructure of the lubricating coating provided by an embodiment of the present application;

[0039] Figure 2 Friction coefficient diagram of the lubricating coatings provided by the embodiments and comparative examples of the present application at different temperatures;

[0040] Figure 3 Wear rate diagram of the lubricating coatings provided by the embodiments and comparative examples of the present application at different temperatures;

[0041] Figure 4 Three-dimensional contour diagram of the wear scar of the lubricating coating provided by Embodiment 3 of the present application;

[0042] Figure 5 Three-dimensional contour diagram of the wear scar of the lubricating coating provided by Comparative Example 6 of the present application;

[0043] Figure 6 Antioxidation schematic diagram of the lubricating coating provided by Embodiment 3 of the present application;

[0044] Figure 7 Antioxidation schematic diagram of the lubricating coating provided by Comparative Example 5 of the present application;

[0045] Figure 8 Antioxidation schematic diagram of the lubricating coating provided by Comparative Example 7 of the present application. Detailed Description of the Embodiments

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following clearly and completely describes the technical solutions in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts also belong to the scope of protection of this application.

[0047] This application provides a lubricating coating based on silane-modified aluminum chromate phosphate. The lubricating coating includes components in the following weight percentages:

[0048] Lubricant, the lubricant includes 5-10% metal sulfide, 5-10% boron nitride, and 5-15% graphite. The metal sulfide is molybdenum disulfide or tungsten disulfide.

[0049] Binder 11-25%, the binder is a silane-modified aluminum chromate phosphate binder.

[0050] Antioxidant 1-5%, the antioxidant is a rare earth fluoride, including: cerium trifluoride or lanthanum trifluoride.

[0051] Toughening and anti-wear agent, the toughening and anti-wear agent includes 5-10% anti-wear agent and 5-15% anti-wear filler. The anti-wear agent includes one or more of corundum, glass powder, and glass fiber powder; the anti-wear filler is a metal oxide, and the metal oxide is one or more of aluminum oxide, chromium oxide, titanium oxide, and silicon oxide.

[0052] The balance is water.

[0053] Specifically, a powdery solid lubricant and other additives (such as antioxidants, toughening anti-wear agents) are adhered to a metal substrate using a binder, thereby playing a lubricating role. Among them, the lubricants are metal sulfides, boron nitride, and graphite. The metal sulfide is molybdenum disulfide or tungsten disulfide. Molybdenum disulfide and tungsten disulfide are currently widely used solid lubricants. Molybdenum disulfide has a two-dimensional layered structure, with sulfur atoms firmly bonded to molybdenum atoms, and relatively strong compressive properties. The sulfur in molybdenum disulfide is an active element, which can have a strong adsorption effect with the metal surface, enhancing the adhesion ability between the lubricating coating and the metal surface. Thus, during the friction process, the lubricating coating is difficult to be damaged, improving the anti-friction and anti-wear performance of the metal surface. Tungsten disulfide has a hexagonal lattice and is an important lubricating material. It is not only suitable for lubrication under normal conditions but also can be used for lubrication under harsh conditions such as high temperature, high pressure, high vacuum, high load, radiation, and corrosive media. It is a recognized lubricating material with good effects. Moreover, the binding force between sulfur atom layers is weak, and during the friction process, it is easy to slip along the S-S plane, thus showing a relatively small friction coefficient. During the friction process, when the two metal surfaces just come into contact, tungsten disulfide particles, together with the binder, toughening anti-wear agent, and antioxidant, form a film on the metal surface. The tungsten disulfide particles are deposited in the depressions on the metal surface, playing a filling role and forming a surface deposition film, thereby reducing the roughness of the relative surface and the friction and wear of the sliding surface. When the load increases and the friction intensifies, tungsten disulfide chemically reacts with the metal substrate surface to form a ferrous sulfide film. The ferrous sulfide film has excellent lubricating properties and can effectively prevent direct contact between the metal surfaces, thus significantly reducing the wear between the metal surfaces. At high temperatures, tungsten disulfide slowly oxidizes to form tungsten oxide. The formation of oxidation can inhibit the further oxidation of tungsten disulfide, and tungsten oxide has a very low friction coefficient and lubricating properties similar to those of tungsten disulfide, thus also being able to play a role in reducing the wear between the metal surfaces. Boron nitride has a layered structure similar to that of graphite, and the surface interaction force is weak. When used in a lubricating coating, during friction, it is easy for layers to slide between each other, and it has good lubricating properties even at high temperatures. At the same time, it can improve the hardness and load-bearing capacity of the coating.

[0054] The silane-modified aluminum chromophosphate binder uses an acid-type aluminum chromophosphate salt and modifies the aforementioned phosphate with a silane prepolymer. By introducing the Si-O-P structure into the P-O-P network of the phosphate structure, it enhances the toughness of the phosphate while also improving the impact resistance of the coating, improving the interfacial bonding between the binder and the lubricant, effectively covering the structural defects of the lubricant, increasing the bonding strength between the coating and the substrate surface, also improving the friction reduction and wear resistance performance of the coating, and at the same time enhancing its high-temperature oxidation resistance. The introduction of the toughening and anti-wear agent greatly improves the wear resistance of the coating and extends the service life of the coating. The anti-wear agent includes one or more of corundum, glass powder, and glass fiber powder, which have relatively high strength, and thus can improve the strength of the lubricating coating, enabling the lubricating coating to bear stronger pressure during the friction process, thereby improving the wear resistance of the coating. The anti-wear filler is a metal oxide, and the metal oxide is one or more of aluminum oxide, chromium oxide, titanium oxide, and silicon oxide. The metal oxide has good antioxidant performance and can act synergistically with the antioxidant, helping the lubricating coating to still have good antioxidant properties at high temperatures, maintaining the stability of the properties of the lubricating coating to ensure the lubricating performance of the lubricating coating, so as to achieve the purpose of improving the friction reduction and wear resistance performance of the lubricating coating.

[0055] In this application, the lubricant contains 5-10% metal sulfide, 5-10% boron nitride, and 5-15% graphite, 11-25% silane-modified aluminum chromophosphate binder, 1-5% antioxidant, and the toughening and anti-wear agent includes 5-10% anti-wear agent and 5-15% anti-wear filler. The components are compounded and synergistically interact with each other. The combined action enables the lubricating coating to be not only suitable for friction at room temperature but also applicable to friction at high temperatures. A lubricating film is formed between the metal and the friction pair, preventing direct contact between the metal surface and the friction pair. When the lubricating coating is applied to the metal surface of the parts generating friction, it not only does not require changing the dimensions of the parts but also achieves a low-friction lubrication effect of the lubricating coating within a wide temperature range, improving the friction reduction and wear resistance performance of the metal parts. The schematic diagram of the microscopic structure of the lubricating coating provided in this application is as Figure 1 shown.

[0056] Through the above solutions, the present application achieves the low-friction and anti-wear lubrication effect of the lubricating coating in a wide temperature range. By using acid chromium aluminum phosphate and modifying the phosphate with a silane prepolymer, an Si-O-P structure is introduced into the P-O-P network of the phosphate structure to obtain a silane-modified aluminum chromium phosphate binder. While enhancing the toughness of the binder, it also improves the impact resistance of the coating, improves the interfacial bonding between the binder and the lubricant, effectively covers the structural defects of the lubricant, improves the bonding force between the coating and the substrate surface, and also improves the friction-reducing and wear-resistant properties of the coating. By using metal sulfides, boron nitride, and graphite in combination as lubricants, and taking advantage of the good slip ability between the lamellae of the two-dimensional layered structures of boron nitride and graphite, it is easy for the layers to slide during friction, thus reducing the friction coefficient between the metal surface and the friction pair and having a friction-reducing effect. The active element sulfur in the metal sulfide can have a strong adsorption effect on the metal surface, enhancing the adhesion ability between the lubricating coating and the metal surface, so that the lubricating coating is difficult to be damaged during friction and the anti-friction and anti-wear properties of the metal surface are improved. By using a toughening and anti-wear agent to increase the strength of the lubricating coating, the lubricating coating can bear stronger pressure during friction, thereby improving the wear resistance of the coating. The lubricant acts synergistically with the silane-modified aluminum chromium phosphate binder, the toughening and anti-wear agent, and the antioxidant to form a film on the metal surface. By increasing the strength of the lubricating coating, the wear rate of the lubricating coating is reduced, and by increasing the flexibility and impact resistance strength of the lubricating coating, the wear resistance, the continuity of the lubricating film, and the pressure-bearing capacity are improved. By increasing the antioxidant property of the lubricating coating, the temperature resistance of the lubricating coating is improved, enabling the lubricating coating to be applied to metal parts under wide temperature working conditions, and thus generally improving the friction-reducing and anti-wear properties of the lubricating coating.

[0057] Through the lubricating coating provided by the present application, it can not only be applied to the lubrication of metal surfaces at room temperature, but also to fasteners under high-temperature conditions, sliding components, such as the friction seals on the surface of the rudder bearings and control devices of space shuttles, the seals of gas turbine blades and casings, many components of various engines such as those in aerospace and marine vessels, and high-temperature lubrication involved in the process of weapon launch.

[0058] Optionally, the graphite is colloidal graphite, the particle size of the graphite is ≤5 μm, the particle sizes of the metal sulfide, boron nitride, rare earth fluoride, and metal oxide are all ≤10 μm, and the particle size of the anti-wear agent is 40 - 2500 mesh.

[0059] Specifically, controlling the particle sizes of graphite, metal sulfides, boron nitride, rare earth fluorides, and metal oxides. Small particle sizes enable the particles to deposit in the depressions on the metal surface during friction, playing a leveling role and forming a surface deposition film, thereby reducing the surface roughness of the metal and the frictional wear of the metal sliding surface. If the particle sizes are too small, the particles will agglomerate during friction, destroying the continuity of the lubricating film formed by the lubricating coating and failing to achieve the effect of reducing friction and wear resistance. If the particle sizes are too large, the leveling effect of the particles cannot be exerted in a timely manner, which is not conducive to the reduction of friction and wear resistance of the lubricating coating.

[0060] A preparation method of a lubricating coating based on silane-modified aluminum chromate phosphate. The preparation method of the lubricating coating includes the following steps:

[0061] (1) Preparation of solid dispersion slurry: Put the proportionally weighed lubricant, antioxidant, and toughening and anti-wear agent into a ball mill tank. Also add pyrroloquinoline quinone and aluminum glycinate to the ball mill tank, add water to make it into a paste, and ball mill for 12 - 48 h to obtain a solid dispersion slurry.

[0062] (2) Preparation of lubricating coating to be dispersed: Mix the ground solid dispersion slurry with a silane-modified aluminum chromate phosphate binder, and add water until the solid content is 30 - 40% to obtain a lubricating coating to be dispersed.

[0063] (3) Preparation of lubricating coating: Disperse the prepared lubricating coating to be dispersed on a high-speed disperser, and disperse it for 10 - 20 min under the condition of a rotation speed of 5000 - 8000 r / min to obtain the lubricating coating.

[0064] Specifically, ball milling reduces the particle sizes of the solid formulation to further reduce the particle sizes of each solid component, and at the same time makes the particle sizes uniform and fully mixed, and can also improve the dispersibility of each component in water. Ball milling has a great improvement on the uniformity and tribological properties of the lubricating coating. The silane-modified aluminum chromate phosphate binder has a bonding effect. If the binder is first mixed with the solid particles, it will cause problems such as agglomeration and difficulty in dispersion of the solid particles. Therefore, first mixing the solid particles with water to disperse the solid particles and then mixing them with the binder not only saves time and effort in operation, but also can significantly improve the dispersibility of the solid particles.

[0065] At the same time, the solid content of the lubricating coating to be dispersed is 30 - 40% to facilitate the control of the thickness of the lubricating coating during spraying. If the solid content is large, the thickness of the lubricating coating is likely to be thick during spraying. If the solid content is small, the water content is large, and spraying needs to be carried out multiple times during spraying, making the spraying operation complicated. And when the water content is large, the curing time required for the lubricating coating will be prolonged, reducing the work efficiency. The dispersant makes the components in the lubricating coating further evenly distributed.

[0066] Optionally, the preparation method of the silane-modified aluminum chromophosphate binder is as follows:

[0067] (1) Dilute phosphoric acid with deionized water to a phosphoric acid aqueous solution with a mass fraction of 60%. The phosphoric acid used has a content of ≥85%. Then add chromium trioxide and stir until completely dissolved, and then raise the temperature to 80 - 85°C.

[0068] (2) Add aluminum hydroxide in batches. After the aluminum hydroxide is completely dissolved, control the reaction temperature at 100 - 125°C and react for 1 - 3 h.

[0069] (3) Add organic amine, cool down to 35 - 55°C, add silane prepolymer, continue to react for 1 - 5 h, and then naturally cool to room temperature to obtain the silane-modified aluminum chromophosphate binder. Adjust the solid content of the silane-modified aluminum chromophosphate binder to 60 - 65% with deionized water for standby.

[0070] Optionally, the molar ratio of aluminum hydroxide to phosphoric acid is 1 - 1.4:3; the molar ratio of aluminum hydroxide to chromium trioxide is 2 - 4:1.

[0071] Optionally, the dosage of the organic amine is 2 - 10% of the mass of the silane-modified aluminum chromophosphate binder, and the dosage of the silane prepolymer is 2 - 20% of the mass of the silane-modified aluminum chromophosphate binder.

[0072] Optionally, the organic amine includes at least one of triethylamine, triethanolamine, ethylenediamine, and hexamethylenetetramine.

[0073] Specifically, the phosphate binder has good high-temperature resistance, stability, and high adhesion. An acid-type chromium aluminum phosphate salt is used, and the phosphate is modified with a silane prepolymer to introduce a Si-O-P structure into the phosphate P-O-P network, enhancing the toughness of the phosphate. On the other hand, the silanol groups generated by the hydrolysis of the siloxane undergo a condensation reaction with the hydroxyl groups on the surface of the lubricant, effectively improving the dispersion and interfacial bonding of each component of the lubricant in the phosphate. The Si-O bond grafts at the structural defects and boundaries of the lubricant, reducing its structural defects and attaching to the surface of the lubricant to prevent oxygen atoms from contacting, thereby improving the high-temperature oxidation resistance of the lubricant. During the coating curing process, the siloxane is further hydrolyzed and crosslinked, which can reduce the porosity of the lubricating coating and improve the density of the lubricating coating.

[0074] Among them, the organic amine is used to adjust the pH value of the reaction system to 3 - 4, which is beneficial to reducing the corrosion of the binder to the metal matrix, and the organic amine will volatilize during the subsequent heating and curing process, restoring the adhesive performance of the binder; at the same time, it helps the subsequent covalent modification of the silane prepolymer. At the same time, the addition of the silane can play a synergistic protection role with the rare earth fluoride for the lubricant, improving the high-temperature oxidation resistance of the lubricant, thereby achieving good lubrication effects of the lubricating coating in a wide temperature range.

[0075] Optionally, the preparation method of the silane prepolymer is as follows:

[0076] Add deionized water to the siloxane, stir and mix, then dropwise add hydrochloric acid for hydrolysis reaction for 0.5 - 1 h, raise the temperature to 55 - 75 °C, continue the reaction for 3 - 8 h, and then naturally cool to room temperature. Remove the excess solvent to obtain the silane prepolymer.

[0077] Optionally, the concentration of hydrochloric acid is 0.5 mol / L, and the molar ratio of siloxane to deionized water is 2 - 3:1. The addition amount of hydrochloric acid is 0.1% of the total weight of siloxane and deionized water.

[0078] Optionally, the siloxane includes one or more of methyltrimethoxysilane, methyldimethoxysilane, aminopropyltriethoxysilane, γ - glycidoxypropyltrimethoxysilane.

[0079] A lubricating coating based on silane - modified aluminum chromate phosphate is formed by applying a lubricating paint on the metal surface and then heating and curing.

[0080] A preparation method of a lubricating coating based on silane - modified aluminum chromate phosphate, the method includes: using a spray gun to apply the lubricating paint on the metal surface and then heating and curing to obtain a solid lubricating coating.

[0081] The curing conditions are: first cure at 120 - 150 °C for 2 h, and then cure at 305 - 315 °C for 1 h.

[0082] Specifically, the paint is sprayed on the part surface under compressed air (oil - free) or compressed nitrogen. During spraying, the metal part surface needs to be pre - treated by degreasing, rust - removing and other surface treatments to remove the sundries and rust on the metal surface, so that the lubricating paint can better bond with the metal surface, improve the bonding ability between the lubricating paint and the metal surface, and thus improve the lubrication effect of the lubricating coating.

[0083] During the curing process, first cure at 120 - 150 °C and then at 305 - 315 °C. Curing at different temperature gradients helps the flatness of the lubricating coating, so that the lubrication performance of the lubricating coating can be fully exerted during the friction process. The lubricating paint is sprayed on the metal surface, and the coating thickness is determined according to the thickness required in the actual operating conditions of the metal part. Therefore, the present application does not specifically limit the thickness of the lubricating coating.

[0084] Further, in the step of preparing the solid dispersion slurry, after putting the proportionally weighed lubricant, antioxidant, and toughening and anti-wearing agent into the ball mill tank, pyrroloquinoline quinone and aluminum dihydroxyglycinate are also added into the ball mill tank, and then ball milling is carried out. Among them, the weight ratio of pyrroloquinoline quinone, aluminum dihydroxyglycinate to the lubricant is 0.5-1:0.1-0.2:1. The carboxyl group contained in pyrroloquinoline quinone can not only react with the carboxyl group in aluminum dihydroxyglycinate to form an ester compound, but also, both pyrroloquinoline quinone and aluminum dihydroxyglycinate contain N element, and the N element can generate p-d back donation with the outer electrons generated on the metal surface. Therefore, the lubricating coating containing pyrroloquinoline quinone and aluminum dihydroxyglycinate can improve the binding force between the lubricating coating and the metal surface, making the bearing capacity of the lubricating coating stronger during the friction process. Moreover, the active groups in pyrroloquinoline quinone and aluminum dihydroxyglycinate can also interact with the silane-modified aluminum chromophosphate binder molecules, improving the dispersion of the lubricant, antioxidant, and toughening and anti-wearing agent in the binder, enhancing the uniformity of the lubricating coating, and further improving the lubrication effect of the lubricating coating. Among them, the dosage of pyrroloquinoline quinone is more than that of aluminum dihydroxyglycinate, which is beneficial to the better interaction between pyrroloquinoline quinone and the silane-modified aluminum chromophosphate binder molecules, and promoting the adsorption stability of the lubricating film on the metal surface during the friction process. The synergistic effect of pyrroloquinoline quinone and aluminum dihydroxyglycinate not only improves the binding force between the lubricating coating and the metal surface, but also improves the dispersion of each component in the silane-modified aluminum chromophosphate binder, making the overall friction-reducing and anti-wearing performance of the lubricating coating significantly improved during the friction process.

[0085] The present invention will be further described in detail below in conjunction with embodiments. However, it should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0086] Example 1:

[0087] A lubricating coating and a preparation method thereof based on silane-modified aluminum chromophosphate, the method comprising the following steps:

[0088] (I) Preparation of silane prepolymer:

[0089] Deionized water is added to the siloxane and stirred and mixed, and then hydrochloric acid with a concentration of 0.5 mol / L is added dropwise for hydrolysis reaction for 0.5-1 h, the temperature is raised to 55-75 °C, and the reaction is continued for 3-8 h, and then it is naturally cooled to room temperature, and the excess solvent is removed to obtain the silane prepolymer. Among them, the molar ratio of siloxane to deionized water is 2-3:1; the addition amount of hydrochloric acid is 0.1% of the total weight of siloxane and deionized water.

[0090] The siloxane is methyltrimethoxysilane.

[0091] (II) Preparation of silane-modified aluminum chromophosphate binder:

[0092] (1) Dilute phosphoric acid with deionized water to a phosphoric acid aqueous solution with a mass fraction of 60%. Add chromium trioxide and stir until completely dissolved, then raise the temperature to 80 - 85 °C.

[0093] (2) Add aluminum hydroxide in batches. After aluminum hydroxide is completely dissolved, control the reaction temperature at 100 - 125 °C and react for 1 - 3 h.

[0094] (3) Add organic amine, cool down to 35 - 55 °C, add silane prepolymer, continue to react for 1 - 5 h, then naturally cool to room temperature to obtain a silane - modified aluminum chromophosphate binder. Adjust the solid content of the silane - modified aluminum chromophosphate binder to 60 - 65% with deionized water for standby.

[0095] Among them, the molar ratio of aluminum hydroxide to phosphoric acid is 1:3; the molar ratio of aluminum hydroxide to chromium trioxide is 2:1; the dosage of organic amine is 2% of the mass of the silane - modified aluminum chromophosphate binder, and the dosage of silane prepolymer is 2% of the mass of the silane - modified aluminum chromophosphate binder.

[0096] The organic amine is triethylamine.

[0097] (III) Preparation of lubricating coating:

[0098] (1) Preparation of solid dispersion slurry: Put the weighed lubricant, antioxidant, and toughening and anti - wear agent in proportion into a ball - milling tank. Also add pyrroloquinoline quinone and aluminum dihydroxyglycinate to the ball - milling tank, add water to make it into a paste, and ball - mill for 12 h to obtain a solid dispersion slurry. The lubricant includes 5% metal sulfide, 5% boron nitride, and 5% graphite. The metal sulfide is molybdenum disulfide; 11% silane - modified aluminum chromophosphate binder, 1% antioxidant, and the antioxidant is cerium trifluoride; 5% anti - wear agent and 5% anti - wear filler. The anti - wear agent is corundum; the anti - wear filler is metal oxide, and the metal oxide is alumina. The weight ratio of pyrroloquinoline quinone, aluminum dihydroxyglycinate to the lubricant is 0.05:0.01:1.

[0099] And the graphite is colloidal graphite, the particle size of graphite ≤ 5 μm, the particle sizes of metal sulfide, boron nitride, rare - earth fluoride, and metal oxide are all ≤ 10 μm, and the particle size of the anti - wear agent is 40 - 2500 mesh.

[0100] (2) Preparation of dispersion - ready lubricating coating: Mix the ground solid dispersion slurry with the silane - modified aluminum chromophosphate binder, and add water to a solid content of 30 - 40% to obtain a dispersion - ready lubricating coating.

[0101] (3) Preparation of lubricating coating: Disperse the prepared dispersion - ready lubricating coating on a high - speed disperser, and disperse it for 10 min under the condition of a rotation speed of 5000 - 7000 r / min to obtain a lubricating coating.

[0102] (4) Spraying a lubricating coating: After applying a lubricating coating material onto the metal surface using a spray gun, it is heated and cured to obtain a solid lubricating coating. In this embodiment, the lubricating coating material is sprayed onto the surface of metal steel.

[0103] The curing conditions are as follows: First, cure at 120 - 150 °C for 2 h, and then cure at 305 - 315 °C for 1 h.

[0104] Example 2:

[0105] A method for preparing a lubricating coating material and a lubricating coating based on silane-modified aluminum chromate phosphate, the method comprising the following steps: The difference from Example 1 is as follows:

[0106] (I) In the preparation of the silane prepolymer: The siloxane is aminopropyltriethoxysilane.

[0107] (II) Preparation of the silane-modified aluminum chromate phosphate binder: The molar ratio of aluminum hydroxide to phosphoric acid is 1.1:3; the molar ratio of aluminum hydroxide to chromium trioxide is 2.5:1; the dosage of the organic amine is 4% of the mass of the silane-modified aluminum chromate phosphate binder, and the dosage of the silane prepolymer is 6% of the mass of the silane-modified aluminum chromate phosphate binder. The organic amine is triethylamine.

[0108] (III) Preparation of the lubricating coating:

[0109] (1) Preparation of the solid dispersion slurry: Weigh the lubricant, antioxidant, and toughening and anti-wear agent in proportion and put them into a ball mill tank. Also add pyrroloquinoline quinone and aluminum dioxoglycinate to the ball mill tank, and add water to make it into a paste state. Ball mill for 21 h to obtain a solid dispersion slurry. The lubricant includes 6% metal sulfide, 6% boron nitride, and 7% graphite. The metal sulfide is molybdenum disulfide 7; 14% silane-modified aluminum chromate phosphate binder, 2% antioxidant, and the antioxidant is cerium trifluoride 2; 6% anti-wear agent and 7% anti-wear filler, and the anti-wear agent is glass powder; the anti-wear filler is a metal oxide, and the metal oxide is aluminum oxide. The weight ratio of pyrroloquinoline quinone, aluminum dioxoglycinate to the lubricant is 0.12:0.02:1.

[0110] Example 3:

[0111] A method for preparing a lubricating coating material and a lubricating coating based on silane-modified aluminum chromate phosphate, the method comprising the following steps: The difference from Example 1 is as follows:

[0112] (I) In the preparation of the silane prepolymer: The siloxane is γ-glycidoxypropyltrimethoxysilane.

[0113] (2) Preparation of silane-modified aluminum chromophosphate binder: The molar ratio of aluminum hydroxide to phosphoric acid is 1.2:3; the molar ratio of aluminum hydroxide to chromium trioxide is 3:1; the dosage of organic amine is 6% of the mass of the silane-modified aluminum chromophosphate binder, and the dosage of silane prepolymer is 10% of the mass of the silane-modified aluminum chromophosphate binder. The organic amine is triethanolamine.

[0114] (3) Preparation of lubricating coating:

[0115] (1) Preparation of solid dispersion slurry: Weigh the lubricant, antioxidant, and toughening and anti-wear agent in proportion and put them into a ball mill tank. Also add pyrroloquinoline quinone and aluminum dioxoglycinate to the ball mill tank, and add water to make it into a paste. Ball mill for 30 h to obtain a solid dispersion slurry. The lubricant includes 7% metal sulfide, 7% boron nitride, and 9% graphite. The metal sulfide is tungsten disulfide; 17% silane-modified aluminum chromophosphate binder, 3% antioxidant, and the antioxidant is lanthanum trifluoride; 7% anti-wear agent and 9% anti-wear filler. The anti-wear agent is corundum and glass powder; the anti-wear filler is metal oxide, and the metal oxide is alumina and chromium oxide. The weight ratio of pyrroloquinoline quinone, aluminum dioxoglycinate to the lubricant is 0.2:0.02:1.

[0116] The microstructure of the obtained lubricating coating is as Figure 1 shown. By using the silane-modified phosphate binder, while improving the toughness of the binder, it improves the interfacial bonding between the binder and the lubricant, effectively covers the structural defects of the lubricant, and improves its high-temperature oxidation resistance; the introduction of the wear-resistant and toughening phase greatly improves the wear resistance of the coating and extends the service life of the coating.

[0117] Example 4:

[0118] A lubricating coating based on silane-modified aluminum chromophosphate and a preparation method thereof. The differences from Example 1 are as follows:

[0119] (1) In the preparation of the silane prepolymer: The siloxane is methyltrimethoxysilane and methyldimethoxysilane.

[0120] (2) Preparation of silane-modified aluminum chromophosphate binder: The molar ratio of aluminum hydroxide to phosphoric acid is 1.3:3; the molar ratio of aluminum hydroxide to chromium trioxide is 4:1; the dosage of organic amine is 8% of the mass of the silane-modified aluminum chromophosphate binder, and the dosage of silane prepolymer is 15% of the mass of the silane-modified aluminum chromophosphate binder. The organic amine is ethylenediamine.

[0121] (3) Preparation of lubricating coating:

[0122] (1) Preparation of solid dispersion slurry: Weigh the lubricant, antioxidant, and toughening and anti-wear agent in proportion and put them into a ball mill tank. Also add pyrroloquinoline quinone and aluminum dioxoglycinate to the ball mill tank, add water to make it into a paste, and ball mill for 40 h to obtain the solid dispersion slurry. The lubricant includes 8% metal sulfide, 8% boron nitride, and 12% graphite. The metal sulfide is tungsten disulfide; 21% of silane-modified aluminum chromophosphate binder, 4% antioxidant, and the antioxidant is lanthanum trifluoride; 8% anti-wear agent and 12% anti-wear filler. The anti-wear agent includes glass powder and glass fiber powder; the anti-wear filler is metal oxide, and the metal oxide is aluminum oxide and silicon oxide. The weight ratio of pyrroloquinoline quinone, aluminum dioxoglycinate to the lubricant is 0.25:0.02:1.

[0123] Example 5:

[0124] A method for preparing a lubricating coating and a lubricating coating based on silane-modified aluminum chromophosphate, the method comprising the following steps: The difference from Example 1 is as follows:

[0125] (I) In the preparation of the silane prepolymer: The siloxane is methyltrimethoxysilane and aminopropyltriethoxysilane.

[0126] (II) Preparation of the silane-modified aluminum chromophosphate binder: The molar ratio of aluminum hydroxide to phosphoric acid is 1.4:3; the molar ratio of aluminum hydroxide to chromium trioxide is 4:1; the dosage of organic amine is 10% of the mass of the silane-modified aluminum chromophosphate binder, and the dosage of the silane prepolymer is 20% of the mass of the silane-modified aluminum chromophosphate binder. The organic amine is hexamethylenetetramine.

[0127] (III) Preparation of the lubricating coating:

[0128] (1) Preparation of solid dispersion slurry: Weigh the lubricant, antioxidant, and toughening and anti-wear agent in proportion and put them into a ball mill tank. Also add pyrroloquinoline quinone and aluminum dioxoglycinate to the ball mill tank, add water to make it into a paste, and ball mill for 48 h to obtain the solid dispersion slurry. The lubricant includes 10% metal sulfide, 10% boron nitride, and 15% graphite. The metal sulfide is tungsten disulfide; 25% of silane-modified aluminum chromophosphate binder, 5% antioxidant, and the antioxidant is lanthanum trifluoride; 10% anti-wear agent and 15% anti-wear filler. The anti-wear agent includes corundum and glass fiber powder; the anti-wear filler is metal oxide, and the metal oxide is aluminum oxide and titanium oxide. The weight ratio of pyrroloquinoline quinone, aluminum dioxoglycinate to the lubricant is 0.3:0.03:1.

[0129] Comparative Example 1:

[0130] A method for preparing a lubricating coating and a lubricating coating based on silane-modified aluminum chromophosphate, the method comprising the following steps: The difference from Example 3 is as follows:

[0131] (III) Preparation of the lubricating coating: The weight ratio of pyrroloquinoline quinone, aluminum glycinate and the lubricant is 0.03:0.02:1.

[0132] Comparative Example 2:

[0133] A lubricating coating based on silane-modified aluminum chromophosphate and a preparation method thereof, the method comprising the following steps: Different from Example 3 in that:

[0134] (III) Preparation of the lubricating coating: The weight ratio of pyrroloquinoline quinone, aluminum glycinate and the lubricant is 0.2:0.008:1.

[0135] Comparative Example 3:

[0136] A lubricating coating based on silane-modified aluminum chromophosphate and a preparation method thereof, the method comprising the following steps: Different from Example 3 in that:

[0137] (III) Preparation of the lubricating coating: The weight ratio of pyrroloquinoline quinone, aluminum glycinate and the lubricant is 0.4:0.02:1.

[0138] Comparative Example 4:

[0139] A lubricating coating based on silane-modified aluminum chromophosphate and a preparation method thereof, the method comprising the following steps: Different from Example 3 in that:

[0140] (III) Preparation of the lubricating coating: The weight ratio of pyrroloquinoline quinone, aluminum glycinate and the lubricant is 0.2:0.04:1.

[0141] Comparative Example 5:

[0142] A lubricating coating of an unmodified phosphate binder and a preparation method thereof, the method comprising the following steps: Different from Example 3 in that:

[0143] Steps (I) and (II) for modifying the phosphate binder are not carried out.

[0144] (III) The lubricant comprises 7% metal sulfide, 7% boron nitride and 9% graphite, and the metal sulfide is tungsten disulfide; 17% phosphate binder, 3% antioxidant, and the antioxidant is lanthanum trifluoride; 7% antiwear agent and 9% antiwear filler, and the antiwear agent is corundum and glass powder; the antiwear filler is metal oxide, and the metal oxide is alumina and chromium oxide. The weight ratio of pyrroloquinoline quinone, aluminum glycinate and the lubricant is 0.2:0.02:1.

[0145] Comparative Example 6:

[0146] A lubricating coating of an unmodified phosphate binder and a preparation method thereof, the method comprising the following steps: Different from Example 3:

[0147] Do not modify the phosphate binder in steps (i) and (ii).

[0148] (iii) The lubricant comprises 7% metal sulfide, 7% boron nitride and 9% graphite, the metal sulfide being tungsten disulfide; 17% phosphate binder, 3% antioxidant, the antioxidant being lanthanum trifluoride; 7% antiwear agent and 9% antiwear filler, the antiwear agent being corundum and glass powder; the antiwear filler being metal oxides, the metal oxides being alumina and chromium oxide. Do not add pyrroloquinoline quinone and aluminum dioxoglycinate.

[0149] Comparative Example 7:

[0150] A lubricating coating based on silane-modified aluminum chromophosphate and a preparation method thereof, the method comprising the following steps: Different from Example 3:

[0151] (iii) The lubricant comprises 7% metal sulfide, 7% boron nitride and 9% graphite, the metal sulfide being tungsten disulfide; 17% silane-modified aluminum chromophosphate binder, 3% antioxidant, the antioxidant being lanthanum trifluoride; 7% antiwear agent and 9% antiwear filler, the antiwear agent being corundum and glass powder; the antiwear filler being metal oxides, the metal oxides being alumina and chromium oxide. Do not add pyrroloquinoline quinone and aluminum dioxoglycinate.

[0152] Experimental Example 1

[0153] Main performance indicators of the lubricating coating (Example 3), and the experimental results are shown in Table 1

[0154] Table 1

[0155]

[0156] For the lubricating coating prepared in Comparative Example 5, the flexibility and impact resistance were tested. The flexibility was 2 mm and the impact resistance was 40 cm. Compared with the lubricating coating prepared in Example 3, the lubricating coating prepared in Example 3, due to the addition of silane-modified aluminum chromophosphate binder, pyrroloquinoline quinone and aluminum dioxoglycinate, and the modification of phosphate by silane prepolymer, introducing Si-O-P structure into the P-O-P network of phosphate structure, enhanced the toughness of phosphate while also improving the impact resistance of the coating, improving the interfacial bonding between the binder and the lubricant, effectively covering the structural defects of the lubricant, and improving the bonding force between the coating and the substrate surface.

[0157] Experimental Example 2

[0158] Friction reduction and antiwear performance test

[0159] Test method: The lubricating coatings prepared in Examples 1 to 5 and Comparative Examples 1 to 7 were taken respectively for friction experiments.

[0160] Test conditions: Ball-on-disk contact, reciprocating wear, test temperature: within the wide temperature range of 25°C, 450°C, and 600°C, load 10 N, frequency 2 Hz, amplitude 6 mm, the counterbody is a 6-mm-diameter ZrO2 ball, and the test time is 30 min.

[0161] Each test example had 3 parallels, and the average values of the friction coefficient and wear rate results in each experiment were taken and compared. The results are as Figure 2 and Figure 3 shown, Figure 2 is the average friction coefficient diagram, Figure 3 is the average wear rate diagram.

[0162] Among them, in Comparative Examples 5 and 6 during the experiments at 450°C and 600°C, the lubricating coating was oxidized within a short time at the beginning of the experiment, the friction coefficient increased sharply, and the coating lost its lubricating effect.

[0163] Observation Figure 2 and Figure 3 shows that the friction coefficients and wear rates of Examples 1 to 5 are significantly lower than those of Comparative Examples 1 - 7. Generally speaking, the friction coefficient is the smallest at 25°C, the friction coefficient at 450°C is slightly higher than that at 600°C, but the difference is not significant, and the friction coefficient is relatively stable. And the binder used in the examples is a silane-modified aluminum chromophosphate binder obtained by modifying phosphate with a silane prepolymer, and pyrroloquinoline quinone and aluminum glycinate were added at the same time. By using acid chromium aluminum phosphate salt and modifying phosphate with a silane prepolymer, an Si-O-P structure was introduced into the P-O-P network of the phosphate structure to obtain a silane-modified aluminum chromophosphate binder. While enhancing the toughness of the binder, it also improved the impact resistance of the coating, improved the interfacial bonding between the binder and the lubricant, effectively covered the structural defects of the lubricant, improved the bonding force between the coating and the substrate surface, and also improved the friction reduction and wear resistance performance of the coating. At the same time, the carboxyl group contained in pyrroloquinoline quinone can not only react with the carboxyl group in aluminum glycinate to form an ester compound. At the same time, both pyrroloquinoline quinone and aluminum glycinate contain N elements, and the N element can generate p-d back coordination with the outer electrons generated on the metal surface. Therefore, the lubricating coating containing pyrroloquinoline quinone and aluminum glycinate can improve the bonding force between the lubricating coating and the metal surface, making the bearing capacity of the lubricating coating stronger during the friction process. And the active groups in pyrroloquinoline quinone and aluminum glycinate can also interact with the silane-modified aluminum chromophosphate binder molecules, improve the dispersibility of the lubricant, antioxidant, and toughening and anti-wear agent in the binder, improve the uniformity of the lubricating coating, and further improve the lubricating effect of the lubricating coating.

[0164] From Comparative Examples 1 to 4, it can be seen that too much or too little addition of pyrroloquinoline quinone and aluminum dihydroxyglycinate will have an adverse effect on the lubricating performance of the lubricating coating. Therefore, adding a quantitative amount of pyrroloquinoline quinone and aluminum dihydroxyglycinate as in Examples 1 to 5 is beneficial to improving the lubricating performance of the lubricating coating.

[0165] From Comparative Examples 5 to 7, it can be seen that the addition of pyrroloquinoline quinone and aluminum dihydroxyglycinate and the modification of the phosphate binder with silane have greatly improved the anti-friction and anti-wear performance of the lubricating coating.

[0166] At the same time, comparing the three-dimensional contour maps of the wear scars of Example 3 and Comparative Example 6 at a temperature of 25 °C ( Figure 4 and Figure 5 ), it was found that after the friction and wear test, the surface of the wear scar of the lubricating coating provided by Example 3 was smoother than that of Comparative Example 6, indicating that Example 3 was normal abrasive wear, while there were obvious pits on the surface of the wear scar of Comparative Example 6, indicating that adhesive wear and fatigue wear occurred during the friction process of Comparative Example 6. The lubricating coating provided by Comparative Example 6 did not use silane to modify the phosphate binder, nor did it add pyrroloquinoline quinone and aluminum dihydroxyglycinate. Further, it shows that the modification of phosphate with silane prepolymer, introducing Si-O-P structure into the P-O-P network of the phosphate structure, to obtain a silane-modified aluminum chromophosphate binder, can enhance the toughness of the binder while also improving the impact resistance of the coating, improving the interfacial bonding between the binder and the lubricant, effectively covering the structural defects of the lubricant, improving the bonding force between the coating and the substrate surface, and also improving the friction reduction and anti-wear performance of the coating. And adding a quantitative amount of pyrroloquinoline quinone and aluminum dihydroxyglycinate, the N element in pyrroloquinoline quinone and aluminum dihydroxyglycinate can generate p-d back coordination with the outer electrons generated on the metal surface. Therefore, the lubricating coating containing pyrroloquinoline quinone and aluminum dihydroxyglycinate can improve the bonding force between the lubricating coating and the metal surface, making the bearing capacity of the lubricating coating stronger during the friction process. And, the active groups in pyrroloquinoline quinone and aluminum dihydroxyglycinate can also interact with the molecules of the silane-modified aluminum chromophosphate binder, improving the dispersibility of the lubricant, antioxidant, and toughening and anti-wear agent in the binder, improving the uniformity of the lubricating coating, and further improving the lubricating effect of the lubricating coating.

[0167] Experimental Example 3

[0168] Antioxidant performance test

[0169] Take the lubricating coatings in Example 3, Comparative Example 5 and Comparative Example 7 and place them in a muffle furnace at 600 °C for 12 h under constant temperature, observe the surface of the lubricating coating, and the obtained results are as shown in Figure 6 、 Figure 7 and Figure 8as shown

[0170] As Figure 6 shown in the lubricating coating of Example 3, after being kept at a constant temperature of 600 °C for 12 h, the whole coating is intact, without cracks, softening, peeling, bubbles, etc. The coating becomes grayish black, and the lubricant is not oxidized.

[0171] However, as Figure 7 shown in the lubricating coating where the phosphate is not modified with silane, although there is no peeling after being kept at a constant temperature of 600 °C for 12 h, the edge of the coating turns white, and white spots appear in the center. The lubricating coating has been oxidized and the coating loses its lubricating effect; in addition, the whole coating is reddish brown, indicating that the carbon steel substrate has been oxidized. This comparative example proves that silane modification has an improving effect on the toughness of the coating and the high-temperature antioxidant ability of the lubricant.

[0172] As Figure 8 shown in the lubricating coating where pyrroloquinoline quinone and aluminum N,N-dihydroxyglycinate are not added, and the phosphate is not modified with silane, almost the whole coating turns white, indicating that the lubricating coating has been oxidized and loses its lubricating effect. Furthermore, it shows that the addition of pyrroloquinoline quinone and aluminum N,N-dihydroxyglycinate also has a promoting effect on the antioxidant performance of the lubricating coating. The active groups in pyrroloquinoline quinone and aluminum N,N-dihydroxyglycinate can also interact with the molecules of the silane-modified aluminum chromophosphate binder, improving the uniformity and antioxidant property of the lubricating coating, and thus achieving an improvement in the lubricating effect of the lubricating coating.

[0173] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A lubricating coating based on silane-modified aluminum chromophosphate, characterized in that, The lubricating coating comprises components in the following weight percentages: Lubricant, the lubricant comprises 5-10% of metal sulfide, 5-10% of boron nitride and 5-15% of graphite, and the metal sulfide is molybdenum disulfide or tungsten disulfide; Binder 11-25%, and the binder is a silane-modified aluminum chromate phosphate binder; Antioxidant 1-5%, and the antioxidant is rare earth fluoride, including: cerium trifluoride or lanthanum trifluoride; Toughening antiwear agent, the toughening antiwear agent comprises 5-10% of antiwear agent and 5-15% of antiwear filler, and the antiwear agent comprises one or more of corundum, glass powder and glass fiber powder; the antiwear filler is metal oxide, and the metal oxide is one or more of aluminum oxide, chromium oxide, titanium oxide and silicon oxide; The lubricating coating further comprises pyrroloquinoline quinone and aluminum dihydroxyglycinate, and the weight ratio of pyrroloquinoline quinone, aluminum dihydroxyglycinate to the lubricant is 0.5-1:0.1-0.2:1; The balance is water.

2. The lubricating coating based on silane-modified aluminum chromate phosphate according to claim 1, wherein The graphite is colloidal graphite, the particle size of the graphite ≤5μm, and the particle sizes of the metal sulfide, the boron nitride, the rare earth fluoride and the metal oxide are all ≤10μm; The particle size of the antiwear agent is 40-2500 mesh.

3. A preparation method of a lubricating coating based on silane-modified aluminum chromate phosphate as described in claim 1 or 2, characterized in that, It includes the following steps: (1) Preparation of solid dispersion slurry: Put the weighed lubricant, antioxidant and toughening antiwear agent into a ball mill tank, and also add pyrroloquinoline quinone and aluminum dihydroxyglycinate to the ball mill tank, add water to make it into a paste, and ball mill for 12-48h to obtain a solid dispersion slurry; (2) Preparation of lubricating coating to be dispersed: Mix the ground solid dispersion slurry with the silane-modified aluminum chromate phosphate binder, and add water to make the solid content 30-40% to obtain the lubricating coating to be dispersed; (3) Preparation of lubricating coating: Disperse the prepared lubricating coating to be dispersed on a high-speed disperser, and disperse for 10min under the condition of a rotation speed of 5000-7000r / min to obtain the lubricating coating.

4. The preparation method of the lubricating coating based on silane-modified aluminum chromate phosphate according to claim 3, wherein The preparation method of the silane-modified aluminum chromate phosphate binder includes: (1) Dilute phosphoric acid with deionized water to a phosphoric acid aqueous solution with a mass fraction of 60%, add chromium trioxide and stir until completely dissolved, and then heat up to 80-85°C; (2) Add aluminum hydroxide in batches, and after the aluminum hydroxide is completely dissolved, control the reaction temperature at 100-125°C and react for 1-3h; (3) Add organic amine, cool down to 35-55°C, add silane prepolymer, continue to react for 1-5h, and then naturally cool to room temperature to obtain the silane-modified aluminum chromate phosphate binder, and adjust the solid content of the silane-modified aluminum chromate phosphate binder to 60-65% with deionized water for standby.

5. The preparation method of the lubricating coating based on silane-modified aluminum chromate phosphate according to claim 4, characterized in that, The molar ratio of aluminum hydroxide to phosphoric acid is 1-1.4:3; the molar ratio of aluminum hydroxide to chromium trioxide is 2-4:1; The dosage of the organic amine is 2-10% of the mass of the silane-modified aluminum chromate phosphate binder, and the dosage of the silane prepolymer is 2-20% of the mass of the silane-modified aluminum chromate phosphate binder.

6. The preparation method of the lubricating coating based on silane-modified aluminum chromophosphate according to claim 4, wherein, The organic amine includes at least one of triethylamine, triethanolamine, ethylenediamine and hexamethylenetetramine.

7. The preparation method of the lubricating coating based on silane-modified aluminum chromium phosphate according to claim 4, characterized in that, The preparation method of the silane prepolymer is as follows: Deionized water is added to the siloxane and stirred to mix. Then, hydrochloric acid with a concentration of 0.5 mol / L is added dropwise for hydrolysis reaction for 0.5 - 1 h. The temperature is raised to 55 - 75 °C, and the reaction continues for 3 - 8 h. After that, it is naturally cooled to room temperature, and the excess solvent is removed to obtain the silane prepolymer; The molar ratio of the siloxane to the deionized water is 2 - 3:1; The addition amount of the hydrochloric acid is 0.1% of the total weight of the siloxane and the deionized water; 8. The preparation method of the lubricating coating based on silane-modified aluminum chromate phosphate according to claim 7, characterized in that, The siloxane includes one or more of methyltrimethoxysilane, methyldimethoxysilane, aminopropyltriethoxysilane, and γ - glycidoxypropyltrimethoxysilane; 9. A lubricating coating based on silane-modified aluminum chromophosphate, characterized in that, The lubricating coating is formed by applying the lubricating paint according to Claim 1 or 2 on the metal surface and then heating and curing; 10. A method for preparing a lubricating coating based on silane-modified aluminum chromate phosphate as described in claim 9, characterized in that, The preparation method of the lubricating coating includes: The lubricating paint according to Claim 1 or 2 is applied on the metal surface by a spray gun, and then heated and cured to obtain the lubricating coating; The curing conditions are: first curing at 120 - 150 °C for 2 h, and then curing at 305 - 315 °C for 1 h.

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