Phosphate-based dry film lubricant coating and preparation and application thereof

Abstract

The application discloses a phosphate-based dry film lubricating coating and preparation and application thereof. The coating is obtained by curing components with the following mass fractions, wherein the components consist of the following ingredients: phosphate binder 15-18 parts, sulfide 3-5 parts, silver powder 4-6 parts, oxygen-containing acid salt 1.5-3.5 parts, and metal oxide 0.2-0.32 parts, antioxidant 0.6-1.2 parts, and surfactant 0.1-0.2 parts, and the rest is solvent. The application solves the problems of weak adhesion between the existing coating and the substrate, wide temperature range lubrication from room temperature to 800 DEG C, large friction coefficient, short wear life and high cost. The coating has good adhesion to the substrate material, excellent flexibility and impact resistance, is environment-friendly, low-cost and has excellent friction-reducing and wear-resisting performance, has a low friction coefficient from room temperature to 800 DEG C, especially a friction coefficient < 0.16 at 800 DEG C, and has a long wear life.

Description

Technical Field

[0001] This invention relates to a dry film lubrication coating, specifically to a phosphate-based dry film lubrication coating and its preparation and application. Background Technology

[0002] High-temperature dry film lubrication coatings can provide high-performance solid lubricating films for friction pairs in high-temperature environments, and are a key technology for solving wear problems in high-tech equipment. To prevent wear protection failures in machinery such as aero-engines, high-thrust rockets, supersonic aircraft, and high-temperature moving parts (high-temperature bearings, turbine disks, and air foil bearings, etc.) in high-temperature environments, it is urgent to develop novel high-temperature adaptive dry film lubrication coatings to meet their stability and reliability requirements under operating conditions.

[0003] Phosphate binders are commonly used inorganic binders, prepared from metal hydroxides or oxides and phosphoric acid. Phosphate-based dry film lubricating coatings have attracted widespread attention due to their excellent high-temperature resistance, strong adhesion, solvent resistance, low cost, and non-toxic and non-polluting properties.

[0004] The adhesion between existing patented phosphate-based high-temperature lubricating coatings and the substrate is relatively weak. In Document 1 (Patent Publication No. CN101906347A), a room-temperature curing water-based high-temperature solid lubricating coating and its preparation method are disclosed, but the coating adhesion is only grade 1-2, and it easily peels off in impact resistance and flexibility tests. Most phosphate-based dry film lubricating coatings have a long-term (>2h) service temperature of less than 800℃, a high coefficient of friction, and are only used on specific parts such as locking nuts and fasteners. In Document 2 (Patent Publication No. CN115260801A), the graphite-based high-temperature lubricating coating has a service temperature of only 510±10℃. Document 3 (Patent Publication No. CN115491247A) discloses a high-temperature resistant solid lubricating coating and its preparation and application; the coating shows significant lubrication at 800℃ (coefficient of friction ≤0.15), but the wear life at this temperature is only 30 minutes, and the coating contains Cr... 3+ This causes environmental pollution. Therefore, it is of great significance to design and prepare phosphate-based dry film lubricating coatings that can withstand harsh working conditions, are environmentally friendly, and are low-cost. Summary of the Invention

[0005] The purpose of this invention is to provide a phosphate-based dry film lubricating coating and its preparation and application, which solves the problems of weak adhesion between existing coatings and substrates, wide temperature range lubrication from room temperature to 800°C, large coefficient of friction, short wear life and high cost. This coating is environmentally friendly, low cost and excellent friction reduction and wear resistance. It has a low coefficient of friction from room temperature to 800°C, especially at 800°C, the coefficient of friction is less than 0.16 and the wear life is long.

[0006] To achieve the above objectives, the present invention provides a phosphate-based dry film lubricating coating, which is obtained by curing a component comprising the following parts by weight: The component, based on a total mass of 100 parts, consists of the following ingredients:

[0007] The composition includes 15-18 parts of phosphate binder, 3-5 parts of sulfide, 4-6 parts of silver powder, 1.5-3.5 parts of oxyacid salt, 0.2-0.32 parts of metal oxide, 0.6-1.2 parts of antioxidant, and 0.1-0.2 parts of surfactant, with the remainder being solvent. During the curing process, the phosphate binder undergoes a dehydration condensation reaction to form inorganic macromolecular chains, ultimately forming a three-dimensional network structure linked by POP bonds.

[0008] The sulfide is any one or more of niobium disulfide, tungsten disulfide, tantalum disulfide, and molybdenum disulfide; the oxyacid salt is any one of barium sulfate, strontium carbonate, calcium sulfate, strontium sulfate, and strontium yttrium.

[0009] The phosphate binder is prepared by mixing and stirring aluminum hydroxide, water and phosphoric acid, and reacting at 110℃~130℃ for 2~3h; the mass ratio of aluminum hydroxide, phosphoric acid and water is 1∶(4~4.6)∶(2~4).

[0010] Preferably, the solid content of the phosphate binder is 60% to 68.4%; the particle size of the silver powder is ≤5μm; the purity of the oxyacid salt is ≥99% and the particle size is ≤5μm; the purity of the metal oxide is ≥99% and the particle size is ≤5μm.

[0011] Preferably, the antioxidant is any one of yttrium trioxide, lead oxide, antimony trioxide, and cerium oxide, with a purity ≥99% and a particle size ≤5μm.

[0012] Preferably, the surfactant is a hydroxy copolymer containing acidic groups.

[0013] More preferably, the hydroxy copolymer containing acidic groups is BYK-4510.

[0014] Preferably, the solvent is a mixed solution of anhydrous ethanol and water in a volume ratio of (35-40):(55-65). In actual production, deionized water is readily available, which can reduce the cost of coating preparation. The use of anhydrous ethanol and deionized water can significantly reduce environmental pollution problems.

[0015] Preferably, the metal oxide is any one or more of magnesium oxide, zinc oxide, silicon dioxide, vanadium pentoxide, iron tetroxide, aluminum oxide and titanium dioxide, and their purity is ≥99% and particle size is ≤5μm.

[0016] This invention provides a method for preparing a phosphate-based dry film lubricating coating as described above, the method comprising:

[0017] (1) At room temperature, the phosphate binder and solvent are mixed and dissolved to obtain a binder solution; the sulfide, silver powder, oxyacid salt, metal oxide, antioxidant and solvent are mixed and stirred to obtain material A; the surfactant and solvent are mixed to obtain material B;

[0018] (2) Mix material A, material B and binder solution obtained in step (1), add solvent, ball mill at room temperature and discharge to obtain lubricating coating;

[0019] (3) Apply the lubricating coating obtained in step (2) to the surface of the part by spraying it with a spray gun, keep it at 100℃~130℃, then heat it to 310℃~330℃ to cure it, cool it, and the phosphate-based dry film lubricating coating is obtained on the surface of the part.

[0020] Preferably, in step (2), the ball milling time is 90-96 hours; in step (3), the heat preservation time is 0.5-1.5 hours; and in step (3), the curing time is 1-3 hours. The curing heating rate is 10-15℃ / min. Too fast a heating rate will cause uneven heating between the coating and the substrate (different coefficients of thermal expansion), affecting the adhesion of the coating. During the curing process, the coating is first kept at 100℃-130℃ for 0.5-1.5 hours, mainly to evaporate the solvent and prevent blistering and fisheye phenomena from occurring in the coating during subsequent crosslinking, which would reduce the performance of the coating. Secondly, curing at 310℃-330℃ for 1-3 hours is to allow the binder to fully crosslink, thereby ensuring the best performance of the obtained coating. If the curing time is less than the above curing time, the coating crosslinking will be insufficient, and the performance will be reduced.

[0021] This invention provides an application of the phosphate-based dry film lubricating coating as described above in the field of lubrication. Under high temperature (800°C) conditions, the coating undergoes a tribochemical reaction, generating AB in situ. x O y The high-temperature lubricating phase, wherein A is Al, Ag, Sr, Ba, Fe, Ca or Pb, B is V, Mo, W, Al or Nb, x is 1 to 14, and y is 1 to 14.

[0022] This invention discloses a phosphate-based dry film lubricating coating, its preparation, and its application. This invention solves the problems of weak adhesion between existing coatings and substrates, wide-temperature-range lubrication from room temperature to 800°C, high coefficient of friction, short wear life, and high cost. It has the following advantages:

[0023] 1. The phosphate binder prepared in this invention undergoes a process of [PO4] during oil bath heating. 3-The ions gradually transform into an uncharged PO4 tetrahedral crystal structure, with oxygen atoms bonding between the crystals. During the coating curing process, the phosphate binder undergoes a dehydration condensation reaction, forming inorganic macromolecular chains, which ultimately encapsulate the part surface in a three-dimensional network structure linked by POP bonds. The polymorphic transformation properties of the phosphate binder are also the main reason for ensuring the high-temperature stability of the coating. After curing, the phosphate binder has strong adhesion to the substrate, high temperature resistance, impact resistance, is water-soluble, and is low in cost.

[0024] 2. This invention achieves comprehensive application performance of high-temperature tribological properties and high-temperature stability of the coating by considering the composition-property relationship of the coating components. Sulfides are all solid lubricating materials with layered structures, satisfying the low-temperature lubrication performance requirements of the coating. The fluidity and lack of low-temperature brittleness of soft silver give it good lubricity in the intermediate temperature range. Oxyacid salts exhibit excellent shear and lubrication properties at high temperatures, making them effective high-temperature solid lubricants. Coatings containing phosphate binders, sulfides, silver, oxyacid salts, metal oxides, antioxidants, and surfactants in specific proportions satisfy lubrication performance at different temperature gradients. Especially at high temperatures (800℃), the coating undergoes a tribochemical reaction, generating AB in situ. x O y (Where A is Al, Ag, Sr, Ba, Fe, Ca or Pb, B is V, Mo, W, Al or Nb, x is 1 to 14, y is 1 to 14) High-temperature lubricating phase, the lubricating phase is transferred to the friction pair interface to form a synergistic lubricating film, which greatly reduces the friction coefficient, extends the service life of the parts, and improves the overall performance of the equipment.

[0025] 3. The phosphate dry film lubricating coating of this invention exhibits good adhesion to the substrate material, as well as excellent flexibility and impact resistance. This coating combines environmental friendliness and low cost with excellent friction-reducing and wear-resistant properties, meeting the requirements of low coefficient of friction from room temperature to 800°C, especially below 0.16 at 800°C, and long wear life. It ensures the stability and reliability of the friction pair in a wide temperature range, making it an ideal candidate material for high-temperature lubrication. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the preparation process of the phosphate binder described in this invention.

[0027] Figure 2 The graph shows the wear life and friction coefficient of the dry film lubricating coating prepared in Example 3 at different temperatures. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The raw materials used in the following examples are as follows:

[0030] The phosphate binder is a clear, transparent, milky-white viscous liquid with a solid content of 60% to 68.4%.

[0031] The sulfides (any one or more of niobium disulfide, tungsten disulfide, tantalum disulfide and molybdenum disulfide) have a purity of ≥99% and a particle size of ≤5μm.

[0032] The particle size of the silver powder is ≤5μm.

[0033] The purity of the oxyacid salts (any one of barium sulfate, strontium carbonate, calcium sulfate, strontium sulfate and strontium yttrium) is ≥99%, and the particle size is ≤5μm.

[0034] The purity of the metal oxides (any one or more of magnesium oxide, zinc oxide, silicon dioxide, vanadium pentoxide, iron tetroxide, aluminum oxide and titanium dioxide) is ≥99%, and the particle size is ≤5μm.

[0035] The antioxidant (any one of yttrium oxide, lead oxide, cerium oxide, and antimony trioxide) has a purity of ≥99% and a particle size of ≤5μm.

[0036] The surfactant is a hydroxyl copolymer containing acidic groups (BYK-4510).

[0037] The solvent is a mixed solution of anhydrous ethanol and deionized water.

[0038] Example 1

[0039] A phosphate-based dry film lubricating coating, based on a total mass of 100g, comprises the following components by weight:

[0040] The composition comprises 15.5g of phosphate binder, 5g of sulfide (niobium disulfide), 6g of silver powder, 3.5g of oxyacid salt (barium sulfate), 0.32g of metal oxides (magnesium oxide and silicon dioxide), 1g of antioxidant (yttrium trioxide), and 0.15g of surfactant, with the balance being 68.53g of solvent. The mass ratio of magnesium oxide to silicon dioxide in the metal oxides is 1:2. The solvent is prepared by volume percentage from 35% anhydrous ethanol and 65% deionized water.

[0041] Preparation methods of phosphate binders, such as Figure 1The preparation flow chart of the phosphate binder of the present invention is shown below:

[0042] Take 50g of aluminum hydroxide, add 170g of deionized water and stir until the aluminum hydroxide is completely wetted and no lumps or agglomeration occur. Add 205g of phosphoric acid and stir continuously. Place the stirred beaker in a constant temperature oil bath and heat to 110℃ for 2.5h. Cool to room temperature to obtain a clear, transparent, milky white, viscous phosphate binder with a solid content of 60%. The mass ratio of aluminum hydroxide, phosphoric acid, and deionized water is 1:4.1:3.4. In the preparation of the phosphate binder, phosphoric acid (H3PO4) is a transparent liquid with a concentration ≥99%. Aluminum hydroxide (Al(OH)3) is a white powder with a purity ≥99%. Deionized water is prepared using laboratory deionized water equipment.

[0043] The method for preparing the above-mentioned phosphate-based dry film lubricating coating includes:

[0044] (1) Add 15.5g of phosphate binder to 20g of solvent and dissolve it completely to obtain a binder solution; add 5g of sulfide (niobium disulfide), 6g of silver powder, 3.5g of oxyacid salt (barium sulfate), 0.32g of metal oxide (magnesium oxide and silicon dioxide) and 1g of antioxidant (yttrium trioxide) to 25g of solvent and stir for 1h to obtain material A; add 0.15g of surfactant to 10g of solvent and dissolve to obtain material B;

[0045] (2) Mix material A, material B and binder solution obtained in step (1), add 13.53g solvent, ball mill at room temperature for 90h, and discharge to obtain lubricating coating;

[0046] (3) Apply the lubricating coating obtained in step (2) to the surface of the part by spraying it with a spray gun, keep it at 100°C for 1 hour, then heat it up (heating rate is 10-15°C / min) to 310°C and cure it for 3 hours. After cooling, the phosphate-based dry film lubricating coating is obtained.

[0047] Example 2

[0048] A phosphate-based dry film lubricating coating, based on a total mass of 100g, comprises the following components by weight:

[0049] The composition consists of 16.5g phosphate binder, 4g sulfide (tantalum disulfide), 5g silver powder, 2g oxyacid salt (strontium carbonate), 0.3g metal oxides (zinc oxide and silicon dioxide), 1.2g antioxidant (lead oxide), and 0.2g surfactant, with the balance being 70.8g solvent. The mass ratio of zinc oxide to silicon dioxide in the metal oxides is 1:2. The solvent is prepared by volume percentage from 37% anhydrous ethanol and 63% deionized water.

[0050] Preparation method of phosphate binder: Weigh 50g of aluminum hydroxide, add 155g of deionized water and stir until the aluminum hydroxide is completely wetted and no lumps or agglomeration occur. Add 215g of phosphoric acid and stir continuously. Place the beaker in a constant temperature oil bath and heat to 120℃ for 2.5h. Cool to room temperature to obtain a clear, transparent, milky white, viscous phosphate binder with a solid content of 63%. The mass ratio of aluminum hydroxide, phosphoric acid, and deionized water is 1:4.3:3.1. In the preparation of phosphate binder, phosphoric acid (H3PO4) is a transparent liquid with a concentration ≥99%. Aluminum hydroxide (Al(OH)3) is a white powder with a purity ≥99%. Deionized water is prepared using laboratory deionized water equipment.

[0051] The method for preparing the above-mentioned phosphate-based dry film lubricating coating includes:

[0052] (1) Add 16.5g of phosphate binder to 20g of solvent and dissolve it completely to obtain a binder solution; add 4g of sulfide (tantalum disulfide), 5g of silver powder, 2g of oxyacid salt (strontium carbonate), 0.3g of metal oxide (zinc oxide and silicon dioxide) and 1.2g of antioxidant (lead oxide) to 25g of solvent and stir for 2h to obtain material A; add surfactant to 10g of solvent and dissolve to obtain material B;

[0053] (2) Mix material A, material B and binder solution obtained in step (1), add 15.8g solvent, ball mill at room temperature for 93h, and discharge to obtain lubricating coating;

[0054] (3) Apply the lubricating coating obtained in step (2) to the surface of the part by spraying it with a spray gun, keep it at 100°C for 1 hour, then heat it to 310°C for 2 hours to cure it, and then cool it to obtain the phosphate-based dry film lubricating coating.

[0055] Example 3

[0056] A phosphate-based dry film lubricating coating, based on a total mass of 100g, comprises the following components by weight:

[0057] The composition comprises 17.5g of phosphate binder, 3g of sulfides (tungsten disulfide and molybdenum disulfide), 4g of silver powder, 1.5g of oxyacid salt (calcium sulfate), 0.25g of metal oxides (magnesium oxide and vanadium pentoxide), 0.8g of antioxidant (cerium oxide), and 0.1g of surfactant, with the balance being 72.85g of solvent. The mass ratio of tungsten disulfide to molybdenum disulfide in the sulfides is 2:1; the mass ratio of magnesium oxide to vanadium pentoxide in the metal oxides is 1:2. The solvent is prepared by volume percentage from 39% anhydrous ethanol and 61% deionized water.

[0058] Preparation method of phosphate binder: Take 50g of aluminum hydroxide, add 135g of deionized water and stir until the aluminum hydroxide is completely wetted and no lumps or agglomeration occur. Add 225g of phosphoric acid and stir continuously. Place the beaker in a constant temperature oil bath and heat to 130℃. React for 3 hours, then cool to room temperature to obtain a clear, transparent, milky white, viscous phosphate binder with a solid content of 66%. The mass ratio of each component is aluminum hydroxide: phosphoric acid: deionized water = 1:4.5:2.7. In the preparation of phosphate binder, phosphoric acid (H3PO4) is a transparent liquid with a concentration ≥99%. Aluminum hydroxide (Al(OH)3) is a white powder with a purity ≥99%. Deionized water is obtained through laboratory deionization water equipment.

[0059] The method for preparing the above-mentioned phosphate-based dry film lubricating coating includes:

[0060] (1) Add 17.5g of phosphate binder to 20g of solvent and dissolve it completely to obtain a binder solution; add 3g of sulfide (tungsten disulfide and molybdenum disulfide), 4g of silver powder, 1.5g of oxyacid salt (barium sulfate), 0.25g of metal oxide (magnesium oxide and vanadium pentoxide) and 0.8g of antioxidant (cerium oxide) to 25g of solvent and stir for 1.5h to obtain material A; add 0.1g of surfactant to 10g of solvent and dissolve to obtain material B;

[0061] (2) Mix material A, material B and binder solution obtained in step (1), add 17.85g solvent, ball mill at room temperature for 96h, and discharge to obtain lubricating coating;

[0062] (3) Apply the lubricating coating obtained in step (2) to the surface of the part by spraying it with a spray gun, keep it at 100°C for 1 hour, then heat it to 310°C for 3 hours to cure it, and then cool it to obtain the phosphate-based dry film lubricating coating.

[0063] Comparative Example 1

[0064] A phosphate-based dry film lubricating coating, based on a total mass of 100g, comprises components substantially the same by weight as in Example 1, except that:

[0065] The mass of the sulfide (niobium disulfide) has been adjusted from 5g to 5.5g.

[0066] The preparation method of the above phosphate binder is exactly the same as that in Example 1.

[0067] The preparation method of the above-mentioned phosphate-based dry film lubricating coating is basically the same as that in Example 1, except that:

[0068] In step (1), the mass of the sulfide (niobium disulfide) is adjusted from 5g to 5.5g;

[0069] A phosphate-based dry film lubricating coating was formed by the same operation as in Example 1.

[0070] Comparative Example 2

[0071] A phosphate-based dry film lubricating coating, based on a total mass of 100g, comprises components substantially the same by weight as in Example 1, except that:

[0072] The mass of the sulfide (niobium disulfide) has been adjusted from 5g to 2.5g.

[0073] The preparation method of the above phosphate binder is exactly the same as that in Example 1.

[0074] The preparation method of the above-mentioned phosphate-based dry film lubricating coating is basically the same as that in Example 1, except that:

[0075] In step (1), the mass of the sulfide (niobium disulfide) is adjusted from 5g to 2.5g;

[0076] A phosphate-based dry film lubricating coating was formed by the same operation as in Example 1.

[0077] Comparative Example 3

[0078] A phosphate-based dry film lubricating coating, based on a total mass of 100g, comprises components substantially the same by weight as in Example 1, except that:

[0079] The weight of the silver powder has been adjusted from 6g to 3.5g.

[0080] The preparation method of the above phosphate binder is exactly the same as that in Example 1.

[0081] The preparation method of the above-mentioned phosphate-based dry film lubricating coating is basically the same as that in Example 1, except that:

[0082] In step (1), the mass of silver powder is adjusted from 6g to 3.5g;

[0083] A phosphate-based dry film lubricating coating was formed by the same operation as in Example 1.

[0084] Comparative Example 4

[0085] A phosphate-based dry film lubricating coating, based on a total mass of 100g, comprises components substantially the same by weight as in Example 1, except that:

[0086] The weight of the silver powder has been adjusted from 6g to 6.5g.

[0087] The preparation method of the above phosphate binder is exactly the same as that in Example 1.

[0088] The preparation method of the above-mentioned phosphate-based dry film lubricating coating is basically the same as that in Example 1, except that:

[0089] In step (1), the mass of silver powder is adjusted from 6g to 6.5g;

[0090] A phosphate-based dry film lubricating coating was formed by the same operation as in Example 1.

[0091] Comparative Example 5

[0092] A phosphate-based dry film lubricating coating, based on a total mass of 100g, comprises components substantially the same by weight as in Example 1, except that:

[0093] The mass of the oxyacid salt (barium sulfate) was adjusted from 3.5g to 1g.

[0094] The preparation method of the above phosphate binder is exactly the same as that in Example 1.

[0095] The preparation method of the above-mentioned phosphate-based dry film lubricating coating is basically the same as that in Example 1, except that:

[0096] In step (1), the mass of the oxyacid salt (barium sulfate) is adjusted from 3.5g to 1g;

[0097] A phosphate-based dry film lubricating coating was formed by the same operation as in Example 1.

[0098] Comparative Example 6

[0099] A phosphate-based dry film lubricating coating, based on a total mass of 100g, comprises components substantially the same by weight as in Example 1, except that:

[0100] The mass of the oxyacid salt (barium sulfate) was adjusted from 3.5g to 4g.

[0101] The preparation method of the above phosphate binder is exactly the same as that in Example 1.

[0102] The preparation method of the above-mentioned phosphate-based dry film lubricating coating is basically the same as that in Example 1, except that:

[0103] In step (1), the mass of the oxyacid salt (barium sulfate) is adjusted from 3.5g to 4g;

[0104] A phosphate-based dry film lubricating coating was formed by the same operation as in Example 1.

[0105] Comparative Example 7

[0106] A phosphate-based dry film lubricating coating, with a total mass of 100g, contains the same components by weight as in Example 1.

[0107] The preparation method of the phosphate binder is basically the same as that in Example 1, except that:

[0108] The mass ratio of aluminum hydroxide, phosphoric acid, and deionized water is 1:3.8:1.5.

[0109] The weighing and preparation methods of the above-mentioned phosphate-based dry film lubricating coating raw materials are exactly the same as those in Example 1.

[0110] Comparative Example 8

[0111] A phosphate-based dry film lubricating coating, with a total mass of 100g, contains the same components by weight as in Example 1.

[0112] The preparation method of the phosphate binder is basically the same as that in Example 1, except that:

[0113] The mass ratio of aluminum hydroxide, phosphoric acid, and deionized water is 1:4.8:4.1.

[0114] The weighing and preparation methods of the above-mentioned phosphate-based dry film lubricating coating raw materials are exactly the same as those in Example 1.

[0115] Experiment 1 tested the performance of the phosphate-based dry film lubricating coatings prepared in Examples 1-3.

[0116] 1. Performance Indicators

[0117] The various properties of the dry film lubricating coatings prepared in Examples 1 to 3 were tested. The specific test conditions and test results are detailed in Table 1.

[0118] Table 1 Performance indicators of phosphate-based dry film lubricating coatings

[0119]

[0120] As shown in Table 1, the phosphate-based dry film lubricating coating prepared by this invention exhibits good bonding with the substrate material and excellent flexibility and impact resistance. The coating showed no cracking, porosity, or bulging after being kept at 800℃ for 6 hours, making it an ideal candidate material for high-temperature lubrication applications.

[0121] 2. Wear life and coefficient of friction

[0122] Examples 1-3 test the tribological properties of the prepared dry film lubricating coatings at different temperatures. Test method: The tests were conducted on an HT-1000 high-temperature tribological testing machine, with a ball-disc contact configuration. Experimental conditions were: load 5 N, rotational speed 0.2 m / s, friction radius 5 mm, and the paired ball was φ6Al2O3. Test temperatures were room temperature, 200℃, 400℃, 600℃, 700℃, 800℃, 900℃, and 1000℃. Specific test conditions and results are detailed in Table 2.

[0123] like Figure 2 The figure shows the wear life and coefficient of friction of the dry film lubricating coating prepared in Example 3 at different temperatures. Figure 2 It can be seen that the coating prepared according to Example 3 has a wear life of 243 min and a friction coefficient of 0.058 at room temperature, and the friction coefficient curve stabilizes after the running-in stage. At 200℃, the coating has a wear life of 184 min and a friction coefficient of 0.11. This is because at room temperature, the sulfides (molybdenum disulfide and tungsten disulfide) have a layered structure, with atoms on the same plane connected by covalent bonds and different planes bound by van der Waals forces, resulting in weak coupling. Under shear force, the crystal planes easily slip, exhibiting good lubrication performance and macroscopically manifested as a low friction coefficient. Furthermore, at room temperature, the sulfides (molybdenum disulfide and tungsten disulfide) in the coating are the main lubricating phase, exhibiting a low friction coefficient. The sulfides have good load-bearing capacity, and their combination with metal oxides further increases the wear life of the coating. With increasing temperature, the friction coefficient curve fluctuates significantly. At 400℃, the coating has a wear life of 98 min and a friction coefficient of 0.21, with the friction coefficient curve showing significant fluctuations. This is because at 400℃, tungsten disulfide is the main lubricating phase, and the lubricating effect of soft silver is not significant. Molybdenum disulfide in the coating begins to oxidize, and the resulting MoO3 has no lubricating properties, exhibiting abrasive wear. It cannot form a continuous lubricating film, leading to large fluctuations in the friction coefficient curve. At 600℃, the coating's wear life is 114 min, and the friction coefficient is 0.18, with similarly large fluctuations in the friction coefficient curve. This is because at 600℃, the sulfides (molybdenum disulfide and tungsten disulfide) are severely oxidized, resulting in a short lubricating film formation time and large fluctuations in the friction coefficient curve. However, during friction, the small amount of silver molybdate and soft silver generated through tribochemical reactions have significant lubricating effects, improving both the coating's wear life and friction coefficient compared to 400℃. At 800℃, the coating's wear life is 136 min, and the friction coefficient is 0.13. The friction coefficient curve gradually stabilizes after the running-in phase. This is because at 800℃, the oxyacid salts in the coating and the large amount of silver molybdate and silver tungstate generated through tribochemical reactions during friction can provide a continuous and stable lubricating film, thus exhibiting excellent high-temperature lubrication performance. When the coating is severely oxidized at 1000℃, the lubrication effect decreases significantly, and both wear life and friction coefficient increase.

[0124] Table 2 Tribological properties of phosphate-based dry film lubricating coatings

[0125]

[0126] As shown in Table 2, the wear life and friction coefficient of the dry film lubricating coatings prepared in Examples 1-3 of the present invention under different temperature ranges at 5 N and 0.2 m / s are as follows: (1) At room temperature, the wear life is 214-243 min and the friction coefficient is 0.058-0.062; (2) At 200℃, the wear life is 131-184 min and the friction coefficient is 0.11-0.14; (3) At 400℃, the wear life is 77-98 min and the friction coefficient is 0.21-0.26; (4) At 600℃, the wear life is 90-114 min and the friction coefficient is 0.18-0.20; (5) At 800℃, the wear life is 119-136 min and the friction coefficient is 0.13-0.15; (6) At 1000℃, the wear life is 19-34 min and the friction coefficient is 0.32-0.40. Therefore, the dry film lubrication coating of the present invention has a low coefficient of friction and a long wear life under conditions ranging from room temperature to 800°C, which can meet the stability and reliability of the friction pair in a wide temperature range environment and improve the overall performance of the equipment.

[0127] Experimental Example 2 analyzes the effect of phosphate-based dry film lubricating coatings from Comparative Examples 1 to 8 on their performance.

[0128] The performance of the phosphate-based dry film lubricating coatings prepared in Comparative Examples 1 to 8 was tested. The specific test conditions and results are detailed in Table 3.

[0129] Table 3 Performance indicators of phosphate-based dry film lubricating coatings

[0130]

[0131]

[0132] Table 3 shows that the adhesion, flexibility, and impact resistance of the dry film lubricating coatings prepared in Comparative Examples 1-8 of this invention are generally reduced. After 6 hours of holding and cooling at 800°C, the coating applied to K465 high-temperature alloy cracked and bulged. Compared with Examples 1-3, the mass fraction of sulfide in Comparative Example 1 was too high, the mass fraction of sulfide in Comparative Example 2 was too low, the mass fraction of silver powder in Comparative Example 3 was too low, the mass fraction of silver powder in Comparative Example 4 was too high, the mass fraction of oxyacid salt in Comparative Example 5 was too low, the mass fraction of oxyacid salt in Comparative Example 6 was too high, the mass ratio of phosphoric acid to deionized water in the preparation of the phosphate binder in Comparative Example 7 was reduced, and the mass ratio of phosphoric acid to deionized water in the preparation of the phosphate binder in Comparative Example 8 was increased.

[0133] Combine Tables 1-3 and Figure 2Analysis showed that the phosphate-based dry film lubricating coating exhibited the best performance when the mass fractions of sulfide, silver powder, oxyacid salt, and aluminum hydroxide, phosphoric acid, and deionized water in the phosphate binder were 3–5 parts, 4–6 parts, 1.5–3.5 parts, and 1:(4–4.6):(2–4). This performance was primarily reflected in wear life, coefficient of friction, coating flexibility, adhesion, impact resistance, and temperature resistance. However, the coating performance significantly decreased when the mass fractions of sulfide, silver powder, oxyacid salt, and phosphoric acid and deionized water in the phosphate binder exceeded the aforementioned ranges.

[0134] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A phosphate-based dry film lubricating coating, characterized in that, The coating is obtained by curing a component comprising the following parts by weight: the component, in a total of 100 parts by weight, consists of the following ingredients: The mixture contains 15-18 parts of phosphate binder, 3-5 parts of sulfide, 4-6 parts of silver powder, 1.5-3.5 parts of oxyacid salt, 0.2-0.32 parts of metal oxide, 0.6-1.2 parts of antioxidant, and 0.1-0.2 parts of surfactant, with the remainder being solvent. During the curing process, the phosphate binder undergoes a dehydration condensation reaction to form inorganic macromolecular chains, which ultimately form a three-dimensional network structure connected by POP bonds. The sulfide is any one or more of niobium disulfide, tungsten disulfide, tantalum disulfide and molybdenum disulfide; The oxyacid salt is any one of barium sulfate, strontium carbonate, calcium sulfate, strontium sulfate, and strontium yttrium. The phosphate binder is prepared by mixing aluminum hydroxide, water and phosphoric acid and stirring, and reacting at 110℃~130℃ for 2~3 hours. The mass ratio of aluminum hydroxide, phosphoric acid and water is 1:(4~4.6):(2~4).

2. The phosphate-based dry film lubricating coating according to claim 1, characterized in that, The solid content of the phosphate binder is 60%~68.4%; the particle size of the silver powder is ≤5μm; the purity of the oxyacid salt is ≥99% and the particle size is ≤5μm; the purity of the metal oxide is ≥99% and the particle size is ≤5μm.

3. The phosphate-based dry film lubricating coating according to claim 1, characterized in that, The antioxidant is any one of yttrium oxide, lead oxide, antimony trioxide, and cerium oxide, with a purity ≥99% and a particle size ≤5μm.

4. The phosphate-based dry film lubricating coating according to claim 1, characterized in that, The surfactant is a hydroxy copolymer containing acidic groups.

5. The phosphate-based dry film lubricating coating according to claim 4, characterized in that, The hydroxy copolymer containing acidic groups is BYK-4510.

6. The phosphate-based dry film lubricating coating according to claim 1, characterized in that, The solvent is a mixture of anhydrous ethanol and water in a volume ratio of (35~40):(55~65).

7. The phosphate-based dry film lubricating coating according to claim 1, characterized in that, The metal oxide is any one or more of magnesium oxide, zinc oxide, vanadium pentoxide, iron tetroxide, aluminum oxide, and titanium dioxide, and its purity is ≥99% and particle size is ≤5μm.

8. A method for preparing a phosphate-based dry film lubricating coating as described in any one of claims 1 to 7, characterized in that, The method includes: (1) At room temperature, the phosphate binder and solvent are mixed and dissolved to obtain a binder solution; the sulfide, silver powder, oxyacid salt, metal oxide, antioxidant and solvent are mixed and stirred to obtain material A; the surfactant and solvent are mixed to obtain material B; (2) Mix material A, material B and binder solution obtained in step (1), add solvent, ball mill at room temperature and discharge to obtain lubricating coating; (3) Apply the lubricating coating obtained in step (2) to the surface of the part by spraying with a spray gun, keep it at 100℃~130℃, then heat it to 310℃~330℃ to cure, cool it, and the phosphate-based dry film lubricating coating is obtained on the surface of the part.

9. The preparation method according to claim 8, characterized in that, In step (2), the ball milling time is 90~96h; in step (3), the heat preservation time is 0.5~1.5h; in step (3), the curing time is 1~3h.

10. The application of a phosphate-based dry film lubricating coating as described in any one of claims 1 to 7 in the field of lubrication, characterized in that, At 800℃, the coating undergoes a chemical reaction, generating AB in situ. x O y The high-temperature lubricating phase, wherein A is Al, Ag, Sr, Ba, Fe, Ca or Pb, B is V, Mo, W, Al or Nb, x is 1~14, and y is 1~14.

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