High-temperature oxidation-resistant industrial gear oil and preparation method thereof

Abstract

The invention provides high-temperature oxidation-resistant industrial gear oil and a preparation method thereof, and belongs to the technical field of lubricating oil. The manganese-doped cerium dioxide is introduced, oxygen vacancies are introduced through manganese doping to improve the oxidation-reduction capacity and the oxidation resistance, and the dispersity and the thermal stability are enhanced through grafting of the antioxidant and coating modification of silicon dioxide; the molybdenum sulfide / boron nitride composite powder is subjected to intercalation modification to increase the interlayer spacing and improve the lubricating property, and the lipophilicity and dispersion stability are improved by grafting long-chain molecules; a base oil system is formed by compounding PAO, synthetic ester and GTL, and the PAO, the synthetic ester and the GTL synergistically provide excellent lubricity, oxidation resistance and viscosity-temperature characteristics and provide a good dispersion medium for the functional filler; through the synergistic effect of the base oil and the filler, the high-temperature oxidation resistance and lubricating performance of the gear oil are improved, the requirements of harsh working conditions are met, and the service life of the oil product is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of lubricating oils and relates to a high-temperature anti-oxidation industrial gear oil and a preparation method thereof. Background Art

[0002] Gear oil is an indispensable component of industrial machinery lubrication systems. Its primary functions include reducing friction, minimizing wear, dissipating heat, and preventing corrosion. These functions are crucial to the proper operation of mechanical equipment and directly impact its efficiency and service life. Gear oil performance not only impacts equipment operation but also production efficiency and economic benefits. Therefore, the research and development of gear oil is particularly important in modern industry.

[0003] With the rapid advancement of industrial technology, the performance of conventional gear oils is facing increasing challenges, particularly in high-temperature, high-load operating environments. Under these demanding conditions, gear oils must withstand higher temperatures and greater pressures. However, existing gear oils often lack the oxidation resistance and stability they offer in these environments. Oxidation reactions at high temperatures can alter the oil's physical and chemical properties, compromising its lubrication performance.

[0004] Most gear oils currently on the market rely on conventional additive systems to enhance their performance. While these additives effectively inhibit oxidation reactions at room temperature, conventional antioxidants readily degrade at high temperatures, weakening their protective effect and failing to provide sustained antioxidant protection. Furthermore, many base oils experience volatility loss and viscosity reduction at high temperatures, which not only compromises lubrication but can also lead to insufficient oil film thickness, exacerbating friction and wear. These deficiencies accelerate gear oil aging, necessitating more frequent replacements, and can also cause premature equipment failure and breakdown. Frequent maintenance and oil changes undoubtedly increase production costs and downtime, impacting overall productivity and economic benefits. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide a high-temperature antioxidant industrial gear oil and a preparation method thereof. The present invention designs a lubricating system suitable for high-temperature antioxidant industrial gear oil: manganese-doped cerium dioxide is introduced as an antioxidant filler, and its redox ability is enhanced by manganese doping and oxygen vacancies are introduced to improve the high-temperature antioxidant performance; further, its dispersibility, thermal stability and antioxidant function are improved by grafting antioxidants and silica coating modification. Molybdenum sulfide / boron nitride composite powder is used as a lubricating filler. The lubrication performance, lipophilicity and dispersion stability are improved by intercalation modification and grafting long-chain molecules to ensure that it exerts excellent lubrication and anti-settling performance under high-temperature conditions. In addition, the compound base oil system consists of PAO, synthetic ester and GTL. The three have complementary properties, providing excellent viscosity-temperature characteristics, lubricity and antioxidant properties, and providing a good medium for the dispersion and stability of functional fillers. The solution of the present invention improves the antioxidant and lubrication performance of gear oil under complex working conditions of high temperature and high pressure, and extends the service life of the oil.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a high-temperature, antioxidant industrial gear oil, the method comprising:

[0008] S1: mixing a cerium nitrate solution and a manganese nitrate solution to obtain a precursor solution, adding a sodium hydroxide solution to adjust the pH and reacting to obtain manganese-doped ceria powder; dispersing the precursor solution with 2,6-di-tert-butyl-p-cresol in an ethanol aqueous solution to obtain a pre-reaction solution, and reacting to obtain graft-modified manganese-doped ceria;

[0009] S2: preparing an ethanol aqueous solution of tetraethoxysilane, adding the grafted modified manganese-doped ceria to react to obtain coated modified manganese-doped ceria;

[0010] S3: preparing a molybdenum sulfide ethanol dispersion, adding sodium tetraborate, adjusting the pH, reacting, and treating to obtain a molybdenum sulfide / boron nitride composite powder; reacting the dispersion with hexadecylphosphonic acid to obtain an intercalated modified molybdenum sulfide / boron nitride composite powder;

[0011] S4: dispersing the intercalated modified molybdenum sulfide / boron nitride composite powder and octadecyl phosphate in toluene to obtain a reaction solution E, and reacting to obtain a grafted modified molybdenum sulfide / boron nitride composite powder;

[0012] S5: PAO, synthetic ester, and GTL are mixed, and rust inhibitors, antifoaming agents, and antioxidants are added to obtain a base oil solvent. Coated modified manganese-doped cerium dioxide and grafted modified molybdenum sulfide / boron nitride composite powders are added and mixed evenly to obtain a high-temperature antioxidant industrial gear oil.

[0013] Specifically, S1: mixing a cerium nitrate solution and a manganese nitrate solution to obtain a precursor solution, adding a sodium hydroxide solution to adjust the pH to obtain a reaction solution A, stirring and precipitating at room temperature, filtering, washing, and drying to obtain a precursor powder, and calcining to obtain a manganese-doped cerium dioxide powder; preparing a manganese-doped cerium dioxide ethanol aqueous solution, adding 2,6-di-tert-butyl-p-cresol to obtain a pre-reaction solution, adjusting the pH to obtain a reaction solution B, stirring and reacting at a constant temperature, filtering, washing, and drying to obtain a grafted manganese-doped cerium dioxide;

[0014] S2: preparing an ethanol aqueous solution of tetraethoxysilane, adding grafted modified manganese-doped cerium dioxide to obtain a mixed solution C, adjusting the pH with ammonia water to obtain a coating reaction solution, reacting at a constant temperature, filtering, washing, and heat-treating to obtain coated modified manganese-doped cerium dioxide;

[0015] S3: Prepare a molybdenum sulfide ethanol dispersion, add a sodium tetraborate solution to obtain a mixed solution, adjust the pH with ammonia water to obtain a reaction solution D, stir at a constant temperature, filter, wash, and calcine in an ammonia atmosphere to obtain a molybdenum sulfide / boron nitride composite powder; add the mixture to a hexadecylphosphonic acid solution to obtain an intercalation reaction solution, react at a constant temperature, filter, wash, and dry to obtain an intercalation-modified molybdenum sulfide / boron nitride composite powder;

[0016] S4: adding the intercalated modified molybdenum sulfide / boron nitride composite powder and octadecyl phosphate to toluene to obtain a reaction solution E, stirring at a constant temperature, filtering, washing, and drying under a nitrogen atmosphere to obtain a grafted modified molybdenum sulfide / boron nitride composite powder;

[0017] S5: PAO, synthetic ester, and GTL are mixed to obtain a pre-base oil solvent, rust inhibitor, antifoaming agent, and antioxidant are added and mixed evenly to obtain a base oil solvent, coated modified manganese doped cerium dioxide and grafted modified molybdenum sulfide / boron nitride composite powder are added and mixed evenly to obtain a high-temperature antioxidant industrial gear oil.

[0018] As a preferred technical solution of the present invention, in step S1, the concentration of the cerium nitrate solution is 0.1-0.3M, for example, it can be 0.1M, 0.12M, 0.14M, 0.16M, 0.18M, 0.20M, 0.22M, 0.24M, 0.26M, 0.28M or 0.3M, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0019] In some optional embodiments, the concentration of manganese nitrate is 0.1-0.2M, for example, 0.1M, 0.11M, 0.12M, 0.13M, 0.14M, 0.15M, 0.16M, 0.17M, 0.18M, 0.19M or 0.2M, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0020] In some optional embodiments, the molar ratio of manganese nitrate to cerium nitrate is 1-2:50, for example, 1:50, 1.1:50, 1.2:50, 1.3:50, 1.4:50, 1.5:50, 1.6:50, 1.7:50, 1.8:50, 1.9:50 or 2:50, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0021] In some optional embodiments, sodium hydroxide solution is added to the precursor solution to adjust the pH to 9-10, for example, it can be 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9 or 10, but it is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0022] In some optional embodiments, the rotation speed of the stirring precipitation of the reaction liquid A is 300-400 rpm, for example, it can be 300 rpm, 320 rpm, 340 rpm, 360 rpm, 380 rpm or 400 rpm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0023] In some optional embodiments, the stirring and precipitation time of the reaction liquid A is 3-4h, for example, it can be 3h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h or 4h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0024] In some optional embodiments, the precursor powder is calcined at a temperature of 600-700°C, for example, 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C or 700°C, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0025] In some optional embodiments, the calcination time of the precursor powder is 2-4h, for example, it can be 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h or 4h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0026] In some optional embodiments, the mass ratio of the manganese-doped cerium dioxide powder to the ethanol aqueous solution is 1:5-10, for example, it can be 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5 or 1:10, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0027] In some optional embodiments, the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 1-3:1, for example, it can be 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or 3:1, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0028] In some optional embodiments, the concentration of 2,6-di-tert-butyl-p-cresol in the pre-reaction liquid is 1-2 wt.%, for example, it can be 1 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, 1.8 wt.%, 1.9 wt.% or 2 wt.%, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0029] In some optional embodiments, the pH of the pre-reaction liquid is adjusted to 7-9, for example, it can be 7, 7.2, 7.4, 7.6, 7.8, 8, 8.2, 8.4, 8.6, 8.8 or 9, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0030] In some optional embodiments, the temperature of the constant temperature stirring of the reaction liquid B is 60-80°C, for example, it can be 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0031] In some optional embodiments, the constant temperature stirring time of the reaction liquid B is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0032] As a preferred technical solution of the present invention, in step S2, the mass fraction of the ethanol aqueous solution of tetraethoxysilane is 1-5wt.%, for example, it can be 1wt.%, 1.4wt.%, 1.8wt.%, 2.2wt.%, 2.6wt.%, 3wt.%, 3.4wt.%, 3.8wt.%, 4.2wt.%, 4.6wt.% or 5wt.%, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0033] In some optional embodiments, the volume ratio of ethanol to water in the ethanol aqueous solution of tetraethoxysilane is 3-4:1, for example, it can be 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1 or 4:1, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0034] In some optional embodiments, the feeding amount of the tetraethoxysilane is 5-15% of the mass of the grafted modified manganese-doped cerium dioxide, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0035] In some optional embodiments, the pH of the mixed solution C is adjusted to 6-9 using ammonia water, for example, it can be 6, 6.3, 6.6, 6.9, 7.2, 7.5, 7.8, 8.1, 8.4, 8.7 or 9, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0036] In some optional embodiments, the temperature of the constant temperature reaction of the coating reaction liquid is 30-40°C, for example, it can be 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C or 40°C, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0037] In some optional embodiments, the constant temperature reaction time of the coating reaction liquid is 2-3h, for example, it can be 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0038] In some optional embodiments, the temperature of the heat treatment is 200-300°C, for example, it can be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C or 300°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0039] In some optional embodiments, the heat treatment time is 30-60 min, for example, it can be 30 min, 33 min, 36 min, 39 min, 42 min, 45 min, 48 min, 51 min, 54 min, 57 min or 60 min, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0040] As a preferred technical solution of the present invention, in step S3, the concentration of the molybdenum sulfide ethanol dispersion is 2-3 mg / mL, for example, it can be 2 mg / mL, 2.1 mg / mL, 2.2 mg / mL, 2.3 mg / mL, 2.4 mg / mL, 2.5 mg / mL, 2.6 mg / mL, 2.7 mg / mL, 2.8 mg / mL, 2.9 mg / mL or 3 mg / mL, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0041] In some optional embodiments, the concentration of the sodium tetraborate solution is 0.1-0.2M, for example, it can be 0.1M, 0.11M, 0.12M, 0.13M, 0.14M, 0.15M, 0.16M, 0.17M, 0.18M, 0.19M or 0.2M, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0042] In some optional embodiments, the molar ratio of molybdenum sulfide to sodium tetraborate is 1:2-3, for example, it can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0043] In some optional embodiments, the mixed solution is adjusted to a pH of 9-10 using ammonia water, for example, it can be 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9 or 10, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0044] In some optional embodiments, the temperature of the constant temperature stirring of the reaction liquid D is 70-80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0045] In some optional embodiments, the constant temperature stirring time of the reaction liquid D is 4-6 hours, for example, it can be 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, 5 hours, 5.2 hours, 5.4 hours, 5.6 hours, 5.8 hours or 6 hours, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0046] In some optional embodiments, the calcination temperature is 800-1000°C, for example, it can be 800°C, 820°C, 840°C, 860°C, 880°C, 900°C, 920°C, 940°C, 960°C, 980°C or 1000°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0047] In some optional embodiments, the calcination time is 2-3h, for example, it can be 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0048] In some optional embodiments, the concentration of the hexadecylphosphonic acid solution is 0.1-0.2M, for example, it can be 0.1M, 0.11M, 0.12M, 0.13M, 0.14M, 0.15M, 0.16M, 0.17M, 0.18M, 0.19M or 0.2M, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0049] In some optional embodiments, the mass ratio of the molybdenum sulfide / boron nitride composite powder to hexadecylphosphonic acid is 1:0.1-0.5, for example, it can be 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45 or 1:0.5, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0050] In some optional embodiments, the temperature of the isothermal reaction of the intercalation reaction liquid is 120-130°C, for example, it can be 120°C, 121°C, 122°C, 123°C, 124°C, 125°C, 126°C, 127°C, 128°C, 129°C or 130°C, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0051] In some optional embodiments, the constant temperature reaction time of the intercalation reaction solution is 6-12 hours, for example, it can be 6 hours, 6.6 hours, 7.2 hours, 7.8 hours, 8.4 hours, 9 hours, 9.6 hours, 10.2 hours, 10.8 hours, 11.4 hours or 12 hours, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0052] As a preferred technical solution of the present invention, in step S4, the mass ratio of the intercalated modified molybdenum sulfide / boron nitride composite powder to toluene is 1:5-10, for example, it can be 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5 or 1:10, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0053] In some optional embodiments, the mass fraction of the octadecyl phosphate in the reaction solution E is 1-2 wt.%, for example, it can be 1 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, 1.8 wt.%, 1.9 wt.% or 2 wt.%, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0054] In some optional embodiments, the temperature of the constant temperature stirring of the reaction liquid E is 50-70°C, for example, it can be 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0055] In some optional embodiments, the constant temperature stirring time of the reaction liquid E is 2-3h, for example, it can be 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0056] In some optional embodiments, the drying temperature is 100-150°C, for example, it can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0057] In some optional embodiments, the drying time is 30-60 min, for example, it can be 30 min, 33 min, 36 min, 39 min, 42 min, 45 min, 48 min, 51 min, 54 min, 57 min or 60 min, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0058] As a preferred technical solution of the present invention, in step S5, the rust inhibitor is any one of methylbenzotriazole and zinc dialkyl dithiophosphate, or a combination of two thereof; the mass fraction of the rust inhibitor in the pre-base oil solvent is 0.1-0.3 wt.%, for example, it can be 0.1 wt.%, 0.12 wt.%, 0.14 wt.%, 0.16 wt.%, 0.18 wt.%, 0.20 wt.%, 0.22 wt.%, 0.24 wt.%, 0.26 wt.%, 0.28 wt.% or 0.3 wt.%, but is not limited to the listed values, and other values not listed within this numerical range are equally applicable.

[0059] In some optional embodiments, the antifoaming agent is polydimethylsiloxane; the mass fraction of the antifoaming agent in the pre-base oil solvent is 0.01-0.05wt.%, for example, it can be 0.01wt.%, 0.014wt.%, 0.018wt.%, 0.022wt.%, 0.026wt.%, 0.03wt.%, 0.034wt.%, 0.038wt.%, 0.042wt.%, 0.046wt.% or 0.05wt.%, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0060] In some optional embodiments, the antioxidant is any one of alkylated diphenylamine and sulfided isobutylene, or a combination of both; the mass fraction of the antioxidant in the pre-base oil solvent is 0.1-0.2 wt.%, for example, it can be 0.1 wt.%, 0.11 wt.%, 0.12 wt.%, 0.13 wt.%, 0.14 wt.%, 0.15 wt.%, 0.16 wt.%, 0.17 wt.%, 0.18 wt.%, 0.19 wt.%, 0.2 wt.%, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0061] The mass ratio of the PAO, synthetic ester and GTL is (40-60): (20-30): (10-20);

[0062] The synthetic ester is any one or more of neopentyl glycol dicaprate, neopentyl glycol dioctanoate, pentaerythritol tetra-n-heptanoate or pentaerythritol tetraoctanoate.

[0063] In a second aspect, the present invention provides a high-temperature, oxidation-resistant industrial gear oil. The high-temperature, oxidation-resistant industrial gear oil comprises a base oil solvent, coated and modified manganese-doped cerium dioxide, and a grafted and modified molybdenum sulfide / boron nitride composite powder, wherein the mass ratio of the base oil solvent, coated and modified manganese-doped cerium dioxide, and grafted and modified molybdenum sulfide / boron nitride composite powder is 100:(0.5-1):(1-2).

[0064] The present invention introduces cerium dioxide as a key functional filler and modifies it by manganese doping to meet the performance requirements of high-temperature antioxidant industrial gear oil. Cerium dioxide is an inorganic functional material with a cubic fluorite structure. Ce in its lattice is 4+ The large radius of the ion gives it good redox performance and structural stability in redox reactions. 4+ / Ce 3+ The reversible conversion between ions into ceria provides excellent redox cycling capabilities, which can inhibit the occurrence of oxidation reactions by capturing and releasing oxygen species. In addition, ceria itself has high thermal stability and is not easily decomposed or denatured in high temperature environments, making it an ideal high-temperature antioxidant material.

[0065] In order to further enhance the antioxidant properties of cerium dioxide, the present invention modifies its lattice structure by manganese doping. Manganese doping is to introduce manganese ions to partially replace the Ce in the cerium dioxide lattice. 4+ This ion substitution induces lattice distortion and is accompanied by the formation of oxygen vacancies because the charge number of manganese ions is lower than that of Ce. 4+ , forcing the overall lattice to balance its charge through missing oxygen atoms. The introduction of oxygen vacancies significantly improves the material's redox performance because they activate oxygen molecules and promote free radical capture at high temperatures, effectively inhibiting the propagation of the oil oxidation reaction chain. Furthermore, the introduction of manganese ions enhances the electron migration ability of ceria, making redox reactions more efficient. This synergistic effect gives manganese-doped ceria enhanced antioxidant capacity and catalytic activity at high temperatures, making it particularly suitable for industrial gear oil systems requiring high-temperature stability.

[0066] Although manganese-doped ceria has excellent antioxidant properties, it still faces some shortcomings in practical applications. After manganese doping, the surface chemical activity of ceria is strong, which easily absorbs water and other impurities, leading to agglomeration between particles. In addition, the interfacial energy between unmodified manganese-doped ceria and the oil phase system is high, resulting in poor dispersibility in the base oil, thus affecting its antioxidant function. To address these problems, the present invention functionalizes manganese-doped ceria by introducing surface grafting modification technology.

[0067] Specifically, 2,6-di-tert-butyl-p-cresol was used as a grafting stabilizer to modify the surface of manganese-doped ceria particles. 2,6-di-tert-butyl-p-cresol is a commonly used phenolic antioxidant. The phenolic hydroxyl groups contained in its molecular structure can chemically bond with the hydroxyl groups or oxygen vacancies on the surface of manganese-doped ceria to form a stable surface binding layer. This process can significantly reduce the surface energy of manganese-doped ceria, enhance the electrostatic repulsion and steric hindrance effect between particles, and thus inhibit particle agglomeration. In addition, the 2,6-di-tert-butyl-p-cresol molecule also contains antioxidant active groups, which can cooperate with manganese-doped ceria to capture free radicals, further improving the antioxidant properties of the material. Therefore, by grafting 2,6-di-tert-butyl-p-cresol, manganese-doped ceria not only exhibits better dispersibility, but also improves its antioxidant function.

[0068] On the basis of grafting modification, the present invention further performs surface coating modification on manganese-doped ceria to improve its thermal and chemical stability. A uniform layer of silica is deposited on the surface of the grafted manganese-doped ceria particles by hydrolysis and polycondensation of tetraethoxysilane under ammonia catalysis. This silica coating has the following multiple functions: silica is a chemically inert material that can effectively isolate external oxygen from contact with manganese-doped ceria, preventing further oxidation at high temperatures, thereby protecting the lattice integrity of the material; secondly, the silica coating can provide additional structural support in high-temperature environments, preventing manganese-doped ceria from losing its activity due to thermal expansion or particle agglomeration; in addition, the silica surface has extremely low interfacial energy and good compatibility with the base oil system, which can significantly reduce the difficulty of dispersing particles in the oil and prevent particles from settling due to agglomeration.

[0069] The present invention introduces molybdenum sulfide and composite-modifies it with boron nitride to form a molybdenum sulfide / boron nitride composite powder to meet the performance requirements of high-temperature, antioxidant industrial gear oils for lubricity, high-temperature stability, and dispersibility. Molybdenum sulfide is a typical two-dimensional layered material, whose crystals are composed of multiple layers of S-Mo-S units interacting through van der Waals forces. This layered structure gives molybdenum sulfide excellent lubricity and anti-wear properties, making it a highly effective solid lubricant. However, molybdenum sulfide has low chemical stability under high-temperature conditions, and its performance may degrade due to oxidation. Therefore, the use of molybdenum sulfide alone cannot fully meet the performance requirements of gear oils under high-temperature and harsh operating conditions.

[0070] To overcome this limitation, the present invention introduces boron nitride to carry out composite modification of molybdenum sulfide. Boron nitride also has a two-dimensional layered structure similar to that of molybdenum sulfide. Its crystals are composed of BN bonds, and the layers are maintained by weak van der Waals forces. This structure not only enables boron nitride to have excellent lubrication properties, but also extremely high chemical inertness and thermal stability, especially exhibiting excellent antioxidant properties under high temperature environments. By compounding molybdenum sulfide with boron nitride, molybdenum sulfide can provide excellent lubrication properties, while boron nitride can provide high-temperature stability and antioxidant properties to the composite material. This synergistic effect significantly improves the comprehensive performance of the material under high-temperature conditions, ensuring its practical application value in industrial gear oils.

[0071] However, because both molybdenum sulfide and boron nitride are layered materials, their interlayer interactions are weak, making them prone to stacking and agglomeration. This results in poor dispersibility of the composite powder in base oil systems. Furthermore, the high slip resistance between the layers limits the further development of their lubrication properties. Therefore, the present invention optimizes the structure of the molybdenum sulfide / boron nitride composite powder through intercalation modification, thereby improving its dispersibility and lubrication properties.

[0072] Specifically, intercalation modification is achieved by introducing the long-chain molecule hexadecylphosphonic acid. The hexadecylphosphonic acid molecule contains a polar phosphate group and a non-polar long-chain alkyl portion. Its phosphate group can interact with the interlayer surfaces of molybdenum sulfide and boron nitride through electrostatic interactions, hydrogen bonds, or van der Waals forces, inserting between the layers. During the intercalation process, the hexadecylphosphonic acid molecules form a regular arrangement between the layers, significantly increasing the interlayer spacing of the molybdenum sulfide and boron nitride layers and weakening the van der Waals forces between the layers, thereby reducing slip resistance. This effect not only significantly improves the lubrication properties of the composite powder, but also effectively enhances its dispersibility in the oil phase system, preventing particle agglomeration and sedimentation in the base oil.

[0073] To further enhance the lipophilicity and dispersion stability of the composite powder by intercalation modification, the present invention also performs surface grafting modification on the intercalation-modified molybdenum sulfide / boron nitride composite powder. This grafting modification is achieved by chemically adsorbing octadecyl phosphate molecules onto the composite powder surface. Octadecyl phosphate molecules consist of polar phosphate groups and long-chain alkyl groups. The phosphate groups firmly bind to the surfaces of molybdenum sulfide and boron nitride through chemical adsorption, while the long-chain alkyl groups extend to the exterior of the powder, forming an oleophilic, hydrophobic barrier. The benefits of grafting modification are primarily manifested in the following aspects: the long-chain alkyl groups significantly enhance the compatibility of the composite powder with the organic base oil, enabling uniform dispersion of the particles in the oil phase and preventing sedimentation or agglomeration caused by interfacial incompatibility. Furthermore, the surface-grafted long-chain alkyl groups provide steric hindrance, significantly weakening interactions between particles and further improving the dispersion stability of the powder in the base oil. Furthermore, the grafted long-chain alkyl groups act as auxiliary lubricants under high temperature conditions, reducing the friction coefficient between gears and further optimizing the tribological properties of the gear oil.

[0074] In the present invention, PAO, synthetic ester and GTL are selected as the base oil composition. PAO is a synthetic oil with a highly saturated molecular structure. Its molecules only contain CC and CH bonds, and almost no double bonds or other functional groups that are easily oxidized, which makes PAO have excellent antioxidant properties and chemical stability. Due to its regular molecular chain, PAO exhibits excellent fluidity in low-temperature environments and can effectively reduce friction and energy loss during low-temperature startup. In addition, the low volatility of PAO can reduce evaporation losses under high-temperature conditions, extend the service life of the oil, and reduce oil consumption. Its excellent high-temperature thermal stability enables it to maintain viscosity and lubrication properties under harsh high-temperature working conditions, making it one of the ideal basic components of industrial gear oil.

[0075] Synthetic esters are a class of synthetic lubricants based on ester compounds, typically formed by esterifying polyols with high-molecular-weight fatty acids. Compared to PAOs, synthetic esters have a higher polarity, which enables them to adsorb firmly to metal surfaces, forming a strong and stable lubricating film, thereby significantly reducing friction and wear. In addition, the presence of ester groups in synthetic ester molecules gives them excellent lubrication properties and extremely strong antioxidant capabilities. The molecular structure of ester compounds also provides high thermal stability, allowing them to maintain chemical stability in high-temperature environments. Synthetic esters also have high lubricating film strength and shear resistance, which can effectively prevent lubricating film rupture under high-pressure conditions. They are an indispensable and important base oil component in gear oils.

[0076] GTL is a high-purity synthetic oil, virtually free of impurities such as aromatics, sulfur, and nitrogen in its molecular structure, resulting in extremely high chemical purity. This highly saturated molecular structure provides GTL with excellent thermo-oxidative stability, significantly inhibiting oxidative degradation even under high-temperature operating conditions. Furthermore, GTL has a high viscosity index, meaning its viscosity is less temperature-dependent, maintaining stable lubrication performance over a wide temperature range. Its low volatility further reduces oil loss during high-temperature operation, extending the life of the gear oil.

[0077] The combination of PAO, synthetic esters, and GTL forms a base oil system with complementary properties, capable of providing comprehensive lubrication protection under high temperature, high pressure, and complex operating conditions: the high-temperature thermal stability and low volatility of PAO and GTL together ensure that the gear oil can maintain stable viscosity under high temperature conditions, significantly reducing evaporation losses; synthetic esters further enhance lubrication protection capabilities under high temperature conditions by forming a strong lubricating film. Secondly, the antioxidant capacity of synthetic esters compensates for the shortcomings of PAO in antioxidant performance, while the high purity and thermal oxidation stability of GTL further enhance the overall antioxidant performance of the system, thereby delaying the oxidative degradation of the oil. In addition, the polar molecules of synthetic esters and the low viscosity characteristics of PAO work together to form a stable lubricating film on the friction surface, while reducing internal friction and significantly improving lubrication efficiency.

[0078] In the present invention, there is a significant synergistic enhancement effect between different functional materials and their modification treatment methods, which provides a solid scientific basis for improving the performance of high-temperature antioxidant industrial gear oil.

[0079] The synergistic effect of manganese-doped cerium dioxide and molybdenum sulfide / boron nitride composite powder under high temperature conditions significantly improves the anti-oxidation and lubrication properties of gear oil. Specifically, through its efficient redox ability, it captures free radicals generated during the oil oxidation process, thereby interrupting the free radical chain reaction and inhibiting the oxidative degradation of the oil. This redox performance is due to Ce 4+ / Ce 3+ The reversible cyclic reaction between manganese ions and manganese ions, as well as the presence of oxygen vacancies in the lattice, enable manganese-doped ceria to continuously play a role in free radical capture.

[0080] The molybdenum sulfide / boron nitride composite powder offers excellent lubrication properties through its layered structure. It forms a low-shear lubricating film at the friction interface, significantly reducing the coefficient of friction and contact stress, thereby reducing frictional heat generation. Furthermore, boron nitride's high-temperature chemical stability ensures its lubrication properties remain unaffected even under high-temperature operating conditions. By reducing frictional heat generation, the composite powder indirectly reduces the oxidation rate of the oil.

[0081] The synergistic effect of these two functional materials enables the gear oil to achieve the dual goals of inhibiting oxidation and reducing friction losses under high-temperature operating conditions. On the one hand, the manganese-doped ceria effectively captures free radicals, significantly inhibiting oil oxidation reactions. On the other hand, the molybdenum sulfide / boron nitride composite powder reduces frictional heat generation through lubrication, fundamentally slowing the oil's oxidation rate. Furthermore, the synergistic effect of manganese-doped ceria and the molybdenum sulfide / boron nitride composite powders extends the oil's operating life under high-temperature and high-pressure conditions, significantly improving gear reliability and efficiency.

[0082] Synergistic Effect of Grafting and Coating Modification of Manganese-Doped Ceria: Grafting 2,6-di-tert-butyl-p-cresol forms an antioxidant functional molecular layer on the surface of the manganese-doped ceria, significantly improving its dispersibility and antioxidant capacity in the oil phase. As a phenolic antioxidant, the phenolic hydroxyl groups of 2,6-di-tert-butyl-p-cresol chemically bond with hydroxyl groups or oxygen vacancies on the surface of the manganese-doped ceria, enhancing the particle surface functionality while reducing particle agglomeration. A silica coating forms a chemically inert protective barrier on the particle surface. This silica coating protects the manganese-doped ceria from further oxidation by oxygen and moisture, enhancing its thermal stability. Furthermore, it reduces the interfacial energy between the particles and the base oil system, further improving their dispersibility and stability. Grafting and coating modifications optimize manganese-doped ceria from both functional and structural stability perspectives. Grafting modification significantly improved the antioxidant properties of the particles, while coating modification further enhanced the thermal stability and dispersibility of the particles. The combination of the two significantly improved the overall performance of manganese-doped ceria in high-temperature gear oil systems.

[0083] The synergistic effect of intercalation and grafting modification of molybdenum sulfide / boron nitride composite powders: Intercalated hexadecylphosphonic acid molecules are inserted into the interlayers of molybdenum sulfide and boron nitride, increasing the interlayer spacing through electrostatic interactions and van der Waals forces, significantly reducing interlayer slip resistance. This modification not only enhances the lubricity of the composite powder but also improves its dispersion in the oil phase, preventing particle agglomeration caused by interlayer stacking. Furthermore, grafting octadecyl phosphate further optimizes the surface properties of the composite powder. The phosphate groups chemically adsorb to the surfaces of molybdenum sulfide and boron nitride, while the long-chain alkyl moiety imparts significant lipophilicity to the particles, significantly improving the compatibility of the composite powder with base oils. Furthermore, the grafted long-chain alkyl groups prevent interparticle agglomeration through steric hindrance, further improving dispersion stability. Intercalation and grafting modifications optimize the molybdenum sulfide / boron nitride composite powder from the perspectives of interlayer structure and surface chemistry, respectively. Intercalation modification primarily targets the internal structure, improving lubricity and dispersibility by reducing interlayer forces; grafting modification, on the other hand, addresses surface chemistry, enhancing lipophilicity and surface stability to improve particle dispersibility and lubricity. These two modification methods complement each other, enabling the composite powder to fully utilize its performance under high-temperature conditions.

[0084] Compared with the prior art, the present invention has the following beneficial effects:

[0085] The present invention achieves a systematic improvement in the performance of ceria particles through manganese doping, grafting modification, and surface coating modification. Manganese doping enhances the redox capacity and high-temperature antioxidant properties of ceria; grafting 2,6-di-tert-butyl-p-cresol enhances the particles' dispersibility and antioxidant properties; and the silica coating further improves the material's thermal stability and dispersion stability. Through these multiple modification methods, manganese-doped ceria can fully demonstrate its function in high-temperature antioxidant industrial gear oils, providing effective protection for the oil and extending its service life.

[0086] The present invention systematically optimizes the structure and surface chemical properties of molybdenum sulfide / boron nitride composite powders through intercalation modification and grafting modification. Intercalation modification significantly improves the lubrication and dispersibility of the composite powder by introducing hexadecylphosphonic acid to increase the interlayer spacing and reduce the interlayer force; grafting modification gives the composite powder better lipophilicity and dispersion stability through the chemical adsorption of octadecyl phosphate molecules, ensuring the long-term dispersion of particles in the oil phase. Ultimately, these modification methods give the molybdenum sulfide / boron nitride composite powders excellent high-temperature lubrication and anti-settling properties, allowing them to fully function in high-temperature antioxidant industrial gear oils, forming a synergistic effect with the base oil system, and providing the gear oil with long-lasting high-temperature protection and lubrication properties.

[0087] By combining three base oils, the base oil system of the present invention not only provides stable lubrication and antioxidant properties at high temperatures, but also exhibits excellent viscosity-temperature characteristics and low volatility, providing a foundation for efficient operation of gear oils under harsh operating conditions. This combined system provides an excellent dispersion medium and a chemically stable environment for the subsequent addition of functional additives, ensuring the full performance of the additives, ultimately achieving a breakthrough improvement in the high-temperature antioxidant and lubrication properties of gear oils. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 The maximum no-seizure load P of the high-temperature antioxidant industrial gear oil provided by Examples 1 to 4 and Comparative Examples 1 to 8 of the present invention is B Value test results;

[0089] Figure 2 The sintering load P of the high-temperature oxidation-resistant industrial gear oil provided by Examples 1 to 4 and Comparative Examples 1 to 8 of the present invention is D Value test results. DETAILED DESCRIPTION

[0090] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.

[0091] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products without further purification or treatment.

[0092] Example 1

[0093] This embodiment provides a high-temperature, anti-oxidation industrial gear oil and a preparation method thereof. The preparation method of the high-temperature, anti-oxidation industrial gear oil specifically comprises the following steps:

[0094] S1: A 0.2M cerium nitrate solution and a 0.1M manganese nitrate solution were mixed to obtain a precursor solution, wherein the molar ratio of manganese nitrate to cerium nitrate was 1.5:50, sodium hydroxide solution was added to adjust the pH to 9 to obtain a reaction solution A, stirred at 300 rpm for precipitation at room temperature for 3 hours, filtered, washed, and dried to obtain a precursor powder, which was calcined at 600°C for 2 hours to obtain a manganese-doped cerium dioxide powder; a manganese-doped cerium dioxide ethanol aqueous solution was prepared, wherein the mass ratio of manganese-doped cerium dioxide powder to the ethanol aqueous solution was 1:5, and the volume ratio of ethanol to deionized water in the ethanol aqueous solution was 2:1, 2,6-di-tert-butyl-p-cresol was added to obtain a pre-reaction solution, wherein the concentration of 2,6-di-tert-butyl-p-cresol in the pre-reaction solution was 1.5wt.%, and the pH was adjusted to 7 to obtain a reaction solution B, which was stirred at a constant temperature of 60°C for 1 hour, filtered, washed, and dried to obtain graft-modified manganese-doped cerium dioxide;

[0095] S2: preparing a 3 wt.% tetraethoxysilane aqueous ethanol solution, wherein the volume ratio of ethanol to water is 3:1, adding grafted manganese-doped cerium dioxide to obtain a mixed solution C, wherein the amount of tetraethoxysilane added is 10% of the mass of the grafted manganese-doped cerium dioxide, adjusting the pH to 6 with ammonia water to obtain a coating reaction solution, reacting at a constant temperature of 30°C for 2.5 hours, filtering, washing, and heat-treating at 200°C for 30 minutes to obtain a coated modified manganese-doped cerium dioxide;

[0096] S3: Prepare a 2 mg / mL molybdenum sulfide ethanol dispersion, add a 0.1 M sodium tetraborate solution to obtain a mixed solution, wherein the molar ratio of molybdenum sulfide to sodium tetraborate is 1:2.5, use ammonia water to adjust the pH to 9 to obtain a reaction solution D, stir at a constant temperature of 70°C for 4 hours, filter, wash, and calcine in an ammonia atmosphere to obtain a molybdenum sulfide / boron nitride composite powder, wherein the calcination temperature is 800°C and the time is 2 hours; add it to a 0.15 M hexadecylphosphonic acid solution to obtain an intercalation reaction solution, wherein the mass ratio of the molybdenum sulfide / boron nitride composite powder to hexadecylphosphonic acid is 1:0.3, react at a constant temperature of 120°C for 10 hours, filter, wash, and dry to obtain an intercalation-modified molybdenum sulfide / boron nitride composite powder;

[0097] S4: adding intercalated modified molybdenum sulfide / boron nitride composite powder and octadecyl phosphate to toluene to obtain a reaction solution E, wherein the mass ratio of intercalated modified molybdenum sulfide / boron nitride composite powder to toluene is 1:8, and the mass fraction of octadecyl phosphate in the reaction solution E is 1.5 wt.%, stirring at a constant temperature of 50°C for 2 h, filtering, washing, and drying at 100°C for 30 min under a nitrogen atmosphere to obtain a grafted modified molybdenum sulfide / boron nitride composite powder;

[0098] S5: PAO, synthetic ester neopentyl glycol dicaprate, and GTL are mixed to obtain a pre-base oil solvent, wherein the mass ratio of PAO, synthetic ester, and GTL is 50:25:15, and 0.2 wt.% of rust inhibitors methylbenzotriazole and zinc dialkyl dithiophosphate, 0.02 wt.% of anti-foaming agent polydimethylsiloxane, and 0.15 wt.% of antioxidants alkylated diphenylamine and sulfide isobutylene are added and mixed evenly to obtain a base oil solvent, and coated modified manganese doped cerium dioxide and grafted modified molybdenum sulfide / boron nitride composite powders are added and mixed evenly to obtain a high-temperature antioxidant industrial gear oil, wherein the mass ratio of base oil solvent, coated modified manganese doped cerium dioxide, and grafted modified molybdenum sulfide / boron nitride composite powders is 100:0.8:1.5.

[0099] Example 2

[0100] This embodiment provides a high-temperature, anti-oxidation industrial gear oil and a preparation method thereof. The preparation method of the high-temperature, anti-oxidation industrial gear oil specifically comprises the following steps:

[0101] S1: A 0.1M cerium nitrate solution and a 0.2M manganese nitrate solution were mixed to obtain a precursor solution, wherein the molar ratio of manganese nitrate to cerium nitrate was 1.8:50, sodium hydroxide solution was added to adjust the pH to 9.5 to obtain a reaction solution A, stirring and precipitating at 360 rpm at room temperature for 3.5 hours, filtering, washing, and drying to obtain a precursor powder, which was calcined at 650°C for 3 hours to obtain a manganese-doped cerium dioxide powder; a manganese-doped cerium dioxide ethanol aqueous solution was prepared, wherein the mass ratio of manganese-doped cerium dioxide powder to the ethanol aqueous solution was 1:8, and the volume ratio of ethanol to deionized water in the ethanol aqueous solution was 1:1, 2,6-di-tert-butyl-p-cresol was added to obtain a pre-reaction solution, wherein the concentration of 2,6-di-tert-butyl-p-cresol in the pre-reaction solution was 1 wt.%, and the pH was adjusted to 8 to obtain a reaction solution B, which was stirred at 70°C for 2 hours, filtered, washed, and dried to obtain a grafted manganese-doped cerium dioxide;

[0102] S2: preparing a 4 wt.% tetraethoxysilane ethanol aqueous solution, wherein the volume ratio of ethanol to water is 3.5:1, adding grafted manganese-doped cerium dioxide to obtain a mixed solution C, wherein the amount of tetraethoxysilane added is 12% of the mass of the grafted manganese-doped cerium dioxide, adjusting the pH to 8 with ammonia water to obtain a coating reaction solution, reacting at a constant temperature of 35°C for 2 hours, filtering, washing, and heat-treating at 280°C for 40 minutes to obtain a coated modified manganese-doped cerium dioxide;

[0103] S3: Prepare a 2.5 mg / mL molybdenum sulfide ethanol dispersion, add a 0.15 M sodium tetraborate solution to obtain a mixed solution, wherein the molar ratio of molybdenum sulfide to sodium tetraborate is 1:2, use ammonia water to adjust the pH to 9.8 to obtain a reaction solution D, stir at a constant temperature of 75°C for 5 hours, filter, wash, and calcine in an ammonia atmosphere to obtain a molybdenum sulfide / boron nitride composite powder, wherein the calcination temperature is 900°C and the time is 2.8 hours; add it to a 0.1 M hexadecylphosphonic acid solution to obtain an intercalation reaction solution, wherein the mass ratio of the molybdenum sulfide / boron nitride composite powder to hexadecylphosphonic acid is 1:0.4, react at a constant temperature of 125°C for 6 hours, filter, wash, and dry to obtain an intercalation-modified molybdenum sulfide / boron nitride composite powder;

[0104] S4: adding intercalated modified molybdenum sulfide / boron nitride composite powder and octadecyl phosphate to toluene to obtain a reaction solution E, wherein the mass ratio of intercalated modified molybdenum sulfide / boron nitride composite powder to toluene is 1:5, and the mass fraction of octadecyl phosphate in the reaction solution E is 1 wt.%, stirring at a constant temperature of 60°C for 2.5 hours, filtering, washing, and drying at 130°C under a nitrogen atmosphere for 50 minutes to obtain a grafted modified molybdenum sulfide / boron nitride composite powder;

[0105] S5: PAO, synthetic ester pentaerythritol tetra-n-heptanoate, and GTL are mixed to obtain a pre-base oil solvent, wherein the mass ratio of PAO, synthetic ester, and GTL is 40:20:10, and 0.1 wt.% of a rust preventive zinc dialkyl dithiophosphate, 0.04 wt.% of an anti-foaming agent polydimethylsiloxane, and 0.1 wt.% of an antioxidant sulfide isobutylene are added and mixed evenly to obtain a base oil solvent, and coated modified manganese doped cerium dioxide and grafted modified molybdenum sulfide / boron nitride composite powders are added and mixed evenly to obtain a high-temperature antioxidant industrial gear oil, wherein the mass ratio of the base oil solvent, coated modified manganese doped cerium dioxide, and grafted modified molybdenum sulfide / boron nitride composite powders is 100:0.5:1.

[0106] Example 3

[0107] This embodiment provides a high-temperature, anti-oxidation industrial gear oil and a preparation method thereof. The preparation method of the high-temperature, anti-oxidation industrial gear oil specifically comprises the following steps:

[0108] S1: A 0.25M cerium nitrate solution and a 0.15M manganese nitrate solution were mixed to obtain a precursor solution, wherein the molar ratio of manganese nitrate to cerium nitrate was 1:50, and a sodium hydroxide solution was added to adjust the pH to 9.7 to obtain a reaction solution A, which was stirred at 380 rpm for precipitation at room temperature for 3.8 hours, filtered, washed, and dried to obtain a precursor powder, which was calcined at 680°C for 3.5 hours to obtain a manganese-doped cerium dioxide powder; a manganese-doped cerium dioxide ethanol aqueous solution was prepared, wherein the mass ratio of the manganese-doped cerium dioxide powder to the ethanol aqueous solution was 1:7.5, and the volume ratio of ethanol to deionized water in the ethanol aqueous solution was 3:1, 2,6-di-tert-butyl-p-cresol was added to obtain a pre-reaction solution, wherein the concentration of 2,6-di-tert-butyl-p-cresol in the pre-reaction solution was 2 wt.%, and the pH was adjusted to 8.5 to obtain a reaction solution B, which was stirred at a constant temperature of 75°C for 2.6 hours, and then filtered, washed, and dried to obtain a grafted manganese-doped cerium dioxide;

[0109] S2: preparing a 1 wt.% tetraethoxysilane aqueous ethanol solution, wherein the volume ratio of ethanol to water is 3.7:1, adding grafted manganese-doped ceria to obtain a mixed solution C, wherein the amount of tetraethoxysilane added is 15% of the mass of the grafted manganese-doped ceria, adjusting the pH to 7 with ammonia water to obtain a coating reaction solution, reacting at a constant temperature of 38°C for 2.8 hours, filtering, washing, and heat-treating at 270°C for 50 minutes to obtain a coated modified manganese-doped ceria;

[0110] S3: A molybdenum sulfide ethanol dispersion with a concentration of 2.8 mg / mL was prepared, and a sodium tetraborate solution with a concentration of 0.18 M was added to obtain a mixed solution, wherein the molar ratio of molybdenum sulfide to sodium tetraborate was 1:2.8, and ammonia water was used to adjust the pH to 9.5 to obtain a reaction solution D, which was stirred at a constant temperature of 78°C for 5.4 hours, filtered, washed, and calcined in an ammonia atmosphere to obtain a molybdenum sulfide / boron nitride composite powder, wherein the calcination temperature was 950°C and the time was 2.5 hours; the mixture was added to a hexadecylphosphonic acid solution with a concentration of 0.2 M to obtain an intercalation reaction solution, wherein the mass ratio of the molybdenum sulfide / boron nitride composite powder to the hexadecylphosphonic acid was 1:0.1, and the mixture was reacted at a constant temperature of 128°C for 8 hours, filtered, washed, and dried to obtain an intercalation-modified molybdenum sulfide / boron nitride composite powder;

[0111] S4: adding intercalated modified molybdenum sulfide / boron nitride composite powder and octadecyl phosphate to toluene to obtain a reaction solution E, wherein the mass ratio of intercalated modified molybdenum sulfide / boron nitride composite powder to toluene is 1:7, and the mass fraction of octadecyl phosphate in the reaction solution E is 1.8 wt.%, stirring at a constant temperature of 65°C for 2.8 h, filtering, washing, and drying at 140°C for 40 min under a nitrogen atmosphere to obtain a grafted modified molybdenum sulfide / boron nitride composite powder;

[0112] S5: PAO, synthetic ester neopentyl glycol dicaprate, neopentyl glycol dioctanoate, pentaerythritol tetraoctanoate and GTL are mixed to obtain a pre-base oil solvent, wherein the mass ratio of PAO, synthetic ester and GTL is 55:28:18, 0.25wt.% of rust inhibitor methylbenzotriazole in the base oil solvent, 0.01wt.% of anti-foaming agent polydimethylsiloxane in the base oil solvent and 0.18wt.% of antioxidant alkylated diphenylamine in the base oil solvent are added and mixed evenly to obtain a base oil solvent, coated modified manganese doped cerium dioxide and grafted modified molybdenum sulfide / boron nitride composite powder are added and mixed evenly to obtain a high-temperature antioxidant industrial gear oil, wherein the mass ratio of base oil solvent, coated modified manganese doped cerium dioxide and grafted modified molybdenum sulfide / boron nitride composite powder is 100:0.9:1.8.

[0113] Example 4

[0114] This embodiment provides a high-temperature, anti-oxidation industrial gear oil and a preparation method thereof. The preparation method of the high-temperature, anti-oxidation industrial gear oil specifically comprises the following steps:

[0115] S1: A 0.3M cerium nitrate solution and a 0.18M manganese nitrate solution were mixed to obtain a precursor solution, wherein the molar ratio of manganese nitrate to cerium nitrate was 2:50, sodium hydroxide solution was added to adjust the pH to 10 to obtain a reaction solution A, stirred at 400 rpm for precipitation at room temperature for 4 hours, filtered, washed, and dried to obtain a precursor powder, which was calcined at 700°C for 4 hours to obtain a manganese-doped cerium dioxide powder; a manganese-doped cerium dioxide ethanol aqueous solution was prepared, wherein the mass ratio of manganese-doped cerium dioxide powder to the ethanol aqueous solution was 1:10, and the volume ratio of ethanol to deionized water in the ethanol aqueous solution was 2.5:1, 2,6-di-tert-butyl-p-cresol was added to obtain a pre-reaction solution, wherein the concentration of 2,6-di-tert-butyl-p-cresol in the pre-reaction solution was 1.8wt.%, and the pH was adjusted to 9 to obtain a reaction solution B. After stirring at 80°C for 3 hours, the reaction was filtered, washed, and dried to obtain graft-modified manganese-doped cerium dioxide;

[0116] S2: preparing a 5 wt.% tetraethoxysilane ethanol aqueous solution, wherein the volume ratio of ethanol to water is 4:1, adding grafted manganese-doped cerium dioxide to obtain a mixed solution C, wherein the amount of tetraethoxysilane added is 5% of the mass of the grafted manganese-doped cerium dioxide, adjusting the pH to 9 with ammonia water to obtain a coating reaction solution, reacting at a constant temperature of 40°C for 3 hours, filtering, washing, and heat-treating at 300°C for 60 minutes to obtain a coated modified manganese-doped cerium dioxide;

[0117] S3: Prepare a 3 mg / mL molybdenum sulfide ethanol dispersion, add a 0.2 M sodium tetraborate solution to obtain a mixed solution, wherein the molar ratio of molybdenum sulfide to sodium tetraborate is 1:3, use ammonia water to adjust the pH to 10 to obtain a reaction solution D, stir at a constant temperature of 80°C for 6 hours, filter, wash, and calcine in an ammonia atmosphere to obtain a molybdenum sulfide / boron nitride composite powder, wherein the calcination temperature is 1000°C and the time is 3 hours; add it to a 0.18 M hexadecylphosphonic acid solution to obtain an intercalation reaction solution, wherein the mass ratio of the molybdenum sulfide / boron nitride composite powder to hexadecylphosphonic acid is 1:0.5, react at a constant temperature of 130°C for 12 hours, filter, wash, and dry to obtain an intercalation-modified molybdenum sulfide / boron nitride composite powder;

[0118] S4: adding intercalated modified molybdenum sulfide / boron nitride composite powder and octadecyl phosphate to toluene to obtain a reaction solution E, wherein the mass ratio of intercalated modified molybdenum sulfide / boron nitride composite powder to toluene is 1:10, and the mass fraction of octadecyl phosphate in the reaction solution E is 2 wt.%, stirring at a constant temperature of 70°C for 3 h, filtering, washing, and drying at 150°C for 60 min under a nitrogen atmosphere to obtain a grafted modified molybdenum sulfide / boron nitride composite powder;

[0119] S5: PAO, synthetic ester neopentyl glycol dioctanoate, pentaerythritol tetra-n-heptanoate, and GTL are mixed to obtain a pre-base oil solvent, wherein the mass ratio of PAO, synthetic ester, and GTL is 60:30:20, and 0.3 wt.% of a rust preventive zinc dialkyl dithiophosphate, 0.05 wt.% of a foaming agent polydimethylsiloxane, and 0.2 wt.% of an antioxidant sulfide isobutylene are added and mixed evenly to obtain a base oil solvent, and coated modified manganese doped cerium dioxide and grafted modified molybdenum sulfide / boron nitride composite powders are added and mixed evenly to obtain a high-temperature antioxidant industrial gear oil, wherein the mass ratio of the base oil solvent, coated modified manganese doped cerium dioxide, and grafted modified molybdenum sulfide / boron nitride composite powders is 100:1:2.

[0120] Comparative Example 1

[0121] This comparative example provides a high-temperature, antioxidant industrial gear oil. The difference from Example 1 is that in S1, the molar ratio of manganese nitrate to cerium nitrate is 3:50, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0122] Comparative Example 2

[0123] This comparative example provides a high-temperature, antioxidant industrial gear oil. The difference from Example 1 is that in S1, the molar ratio of manganese nitrate to cerium nitrate is 0.5:50, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0124] Comparative Example 3

[0125] This comparative example provides a high-temperature, antioxidant industrial gear oil. The difference from Example 1 is that in S3, the molar ratio of molybdenum sulfide to sodium tetraborate is 1:4, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0126] Comparative Example 4

[0127] This comparative example provides a high-temperature, antioxidant industrial gear oil. The difference from Example 1 is that in S3, the molar ratio of molybdenum sulfide to sodium tetraborate is 1:1, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0128] Comparative Example 5

[0129] This comparative example provides a high-temperature, antioxidant industrial gear oil. The difference from Example 1 is that in S5, the mass ratio of the base oil solvent, the coated modified manganese-doped cerium dioxide, and the grafted modified molybdenum sulfide / boron nitride composite powder is 100:2:1.5, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0130] Comparative Example 6

[0131] This comparative example provides a high-temperature, antioxidant industrial gear oil. The difference from Example 1 is that in S5, the mass ratio of the base oil solvent, the coated modified manganese-doped cerium dioxide, and the grafted modified molybdenum sulfide / boron nitride composite powder is 100:0.1:1.5, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0132] Comparative Example 7

[0133] This comparative example provides a high-temperature, antioxidant industrial gear oil. The difference from Example 1 is that in S5, the mass ratio of the base oil solvent, the coated modified manganese-doped cerium dioxide, and the grafted modified molybdenum sulfide / boron nitride composite powder is 100:0.8:3, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0134] Comparative Example 8

[0135] This comparative example provides a high-temperature, antioxidant industrial gear oil. The difference from Example 1 is that in S5, the mass ratio of the base oil solvent, the coated modified manganese-doped cerium dioxide, and the grafted modified molybdenum sulfide / boron nitride composite powder is 100:0.8:0.5, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0136] The performance test of the high-temperature, oxidation-resistant industrial gear oils of Examples 1-4 and Comparative Examples 1-8 was conducted. The specific process is as follows:

[0137] According to GB / T 3142-2019, the load-bearing capacity of lubricating oil (four-ball method) is used to test the load-bearing and anti-sintering properties of the sample. The test results are as follows: Figure 1 、 Figure 2 As shown;

[0138] The anti-wear performance of the samples was tested according to NB / SH / T 0189, Determination of Anti-wear Performance of Lubricating Oils (Four-ball Method);

[0139] The oxidation stability of the samples was tested according to GB / T 12581-2006.

[0140] The test results are shown in Table 1.

[0141] Table 1: Performance test results of high temperature antioxidant industrial gear oils of Examples 1-4 and Comparative Examples 1-8

[0142]

[0143] The test results of Example 1 and Comparative Examples 1 and 2 show that when the molar ratio of manganese nitrate to cerium nitrate is too high, the excess manganese ions destroy the lattice structure of ceria, causing the maximum no-seizure load to drop to 950 N, the sintering load to drop to 1650 N, and the wear scar diameter to increase to 0.42 mm. At the same time, due to the decrease in redox ability, the oxidation stability drops to 850 h. When the molar ratio is too low, insufficient manganese doping leads to a decrease in the number of oxygen vacancies, causing the maximum no-seizure load to drop to 1000 N, the sintering load to drop to 1750 N, the wear scar diameter to increase to 0.40 mm, and the oxidation stability to drop to 920 h.

[0144] The test results of Example 1 and Comparative Examples 3 and 4 show that when the molar ratio of molybdenum sulfide to sodium tetraborate is too low, the excessively thick boron nitride coating hinders the lubricating effect of molybdenum sulfide, causing the maximum no-seizure load to drop to 980 N, the sintering load to drop to 1700 N, the wear scar diameter to increase to 0.41 mm, and the oxidation stability to basically maintain at 1000 h. When the molar ratio is too high, the high-temperature stability decreases due to the incomplete protective layer, causing the maximum no-seizure load to drop to 950 N, the sintering load to drop to 1600 N, the wear scar diameter to increase to 0.43 mm, and the oxidation stability to drop to 900 h.

[0145] The test results of Example 1 and Comparative Examples 5 and 6 show that when the feed rate of the coated modified manganese-doped cerium dioxide is too high, the excess nanoparticles agglomerate, causing the maximum no-seizure load to drop to 1000 N, the sintering load to drop to 1750 N, and the wear scar diameter to increase to 0.39 mm, but the oxidation stability is slightly improved to 1100 h. When the feed rate is too low, due to insufficient antioxidant content, the maximum no-seizure load drops to 1020 N, the sintering load drops to 1800 N, the wear scar diameter is basically maintained at 0.37 mm, and the oxidation stability drops to 900 h.

[0146] From the test results of Example 1 and Comparative Examples 7 and 8, it can be seen that when the feeding amount of the grafted modified molybdenum sulfide / boron nitride composite powder is too high, excessive addition leads to poor dispersibility, so that the maximum no-seizure load drops to 1000N, the sintering load drops to 1700N, the wear scar diameter increases to 0.40mm, and the oxidation stability is basically maintained at 1050h; when the feeding amount is too low, due to insufficient lubricant content, the maximum no-seizure load is significantly reduced to 900N, the sintering load is significantly reduced to 1600N, the wear scar diameter is significantly increased to 0.45mm, and the oxidation stability is basically maintained at 1000h.

[0147] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a high-temperature, antioxidant industrial gear oil, characterized in that: The preparation method comprises: S1: mixing a cerium nitrate solution and a manganese nitrate solution to obtain a precursor solution, adding a sodium hydroxide solution to adjust the pH, reacting, and calcining to obtain manganese-doped cerium dioxide powder; dispersing the precursor solution with 2,6-di-tert-butyl-p-cresol in an ethanol aqueous solution to obtain a pre-reaction solution, and reacting to obtain graft-modified manganese-doped cerium dioxide; S2: preparing an ethanol aqueous solution of tetraethoxysilane, adding the grafted modified manganese-doped ceria to react to obtain coated modified manganese-doped ceria; S3: preparing a molybdenum sulfide ethanol dispersion, adding sodium tetraborate, adjusting the pH, reacting, and treating to obtain a molybdenum sulfide / boron nitride composite powder; reacting the dispersion with hexadecylphosphonic acid to obtain an intercalated modified molybdenum sulfide / boron nitride composite powder; S4: dispersing the intercalated modified molybdenum sulfide / boron nitride composite powder and octadecyl phosphate in toluene to obtain a reaction solution E, and reacting to obtain a grafted modified molybdenum sulfide / boron nitride composite powder; S5: PAO, synthetic ester, and GTL are mixed, and rust inhibitors, antifoaming agents, and antioxidants are added to obtain a base oil solvent. Coated modified manganese-doped cerium dioxide and grafted modified molybdenum sulfide / boron nitride composite powders are added and mixed evenly to obtain a high-temperature antioxidant industrial gear oil.

2. The method for preparing a high-temperature, antioxidant industrial gear oil according to claim 1, characterized in that: In S1, the molar ratio of manganese nitrate to cerium nitrate is 1-2:

50.

3. The method for preparing a high-temperature, antioxidant industrial gear oil according to claim 1, characterized in that: In S1: The mass ratio of the manganese-doped cerium dioxide powder to the ethanol aqueous solution is 1:5-10; The concentration of 2,6-di-tert-butyl-p-cresol in the pre-reaction liquid is 1-2 wt.%.

4. The method for preparing a high-temperature, antioxidant industrial gear oil according to claim 1, wherein: In S2, the volume ratio of ethanol to water in the ethanol aqueous solution of tetraethoxysilane is 3-4:

1.

5. The method for preparing a high-temperature, antioxidant industrial gear oil according to claim 1, characterized in that: In S2: the feeding amount of the tetraethoxysilane is 5-15% of the mass of the graft-modified manganese-doped cerium dioxide.

6. The method for preparing a high-temperature, antioxidant industrial gear oil according to claim 1, characterized in that: In S3: The molar ratio of molybdenum sulfide to sodium tetraborate is 1:2-3; The mass ratio of the molybdenum sulfide / boron nitride composite powder to hexadecylphosphonic acid is 1:0.1-0.

5.

7. The method for preparing a high-temperature, antioxidant industrial gear oil according to claim 1, characterized in that: In S4: The mass ratio of the intercalated modified molybdenum sulfide / boron nitride composite powder to toluene is 1:5-10; The mass fraction of the octadecyl phosphate in the reaction solution E is 1-2 wt.%.

8. The method for preparing a high-temperature, antioxidant industrial gear oil according to claim 1, wherein: In S5: The mass ratio of the PAO, synthetic ester and GTL is (40-60): (20-30): (10-20); The synthetic ester is any one or more of neopentyl glycol dicaprate, neopentyl glycol dioctanoate, pentaerythritol tetra-n-heptanoate or pentaerythritol tetraoctanoate.

9. The method for preparing a high-temperature, antioxidant industrial gear oil according to claim 1, characterized in that: In S5: The rust inhibitor is any one of methylbenzotriazole and zinc dialkyl dithiophosphate, or a combination of the two; The mass fraction of the rust inhibitor in the base oil solvent is 0.1-0.3wt.%; The antifoaming agent is polydimethylsiloxane; The mass fraction of the antifoaming agent in the base oil solvent is 0.01-0.05wt.%; The antioxidant is any one of alkylated diphenylamine and sulfided isobutylene or a combination of the two; The mass fraction of the antioxidant in the base oil solvent is 0.1-0.2 wt.%.

10. A high-temperature, antioxidant industrial gear oil prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The mass ratio of the base oil solvent, the coated modified manganese-doped cerium dioxide and the grafted modified molybdenum sulfide / boron nitride composite powder in the high-temperature antioxidant industrial gear oil is: 100: (0.5-1): (1-2).

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