Lubricating grease composition and preparation method thereof

Abstract

The invention provides a lubricating grease composition and a preparation method thereof, the lubricating grease composition comprises base oil, a thickening agent and an additive, the kinematic viscosity of the base oil at 40 + / -0.1 DEG C is 20-165 mm < 2 > / s; the additive comprises one or more of an antioxidant, a lubricant, an anti-wear reagent at extreme pressure and an anti-rust preservative. The wear degree of the bearing in a micro-vibration environment can be effectively reduced, and the service life of the bearing is prolonged.

Description

Technical Field

[0001] This invention relates to the field of lubricating grease technology, and more specifically to a lubricating grease composition and its preparation method. Background Technology

[0002] Bearings are crucial rotating components in mechanical equipment, and continuous small-amplitude vibrations can damage them. The pitch control system of wind turbine blades is a typical example. During shutdown, wind causes the blades to oscillate slightly along their axis. These oscillations are transmitted to the pitch bearing, causing the rollers to move slightly relative to the bearing race. Additionally, during operation, the wind turbine continuously adjusts the pitch angle, causing the pitch bearing to oscillate. Another typical example is the rolling bearings of trucks or railway vehicles, which are also commonly subjected to small-amplitude vibrations. Vibration causes reciprocating motion between the bearing rollers and raceways. This small-amplitude relative motion leads to wear, which can be categorized as pseudo-Burlman indentation and fretting corrosion. This produces friction reaction products such as magnetite (Fe3O4) or hematite (Fe2O3). Wear particles introduced into the bearing system cause severe abrasive wear, leading to surface damage and significantly impacting the rolling bearing's lifespan.

[0003] However, current technologies do not address the issues of pseudo-Burlman indentation and fretting corrosion wear in rolling bearings under micro-vibration environments. The mechanisms and impacts of rolling bearing damage under vibration conditions have not yet been thoroughly investigated. For a long time, rolling bearings have faced a high risk of premature failure and short lifespan in micro-vibration environments. To prevent wear caused by micro-vibrations, basic methods include using vibration isolators, preloading, bearing surface treatment, and altering bearing surface roughness. However, these methods increase the cost of equipment components. Besides this, selecting a grease with excellent boundary lubrication properties is a simple and effective way to reduce bearing wear. Existing rolling bearing greases have a relatively high consistency. When the bearing rotates, they are distributed near the raceway. Under surface tension, the base oil in the grease seeps out and flows to the friction pair (friction surface) to provide lubrication. However, under vibration environments, existing rolling bearing greases cannot effectively lubricate the bearing, resulting in poor bearing wear resistance.

[0004] Therefore, developing greases suitable for rolling bearings in micro-vibration environments is of great significance for reducing bearing wear and extending bearing service life in such environments. Summary of the Invention

[0005] This invention provides a lubricating grease composition and its preparation method, which can effectively reduce the wear of bearings under micro-vibration environments and improve the service life of bearings.

[0006] In one aspect, the present invention provides a lubricating grease composition comprising a base oil, a thickener, and additives, wherein the base oil has a kinematic viscosity of 20–165 mm at 40°C ± 0.1°C. 2 / s; The additives include one or more of antioxidants, lubricants, extreme pressure anti-wear agents, and rust and corrosion inhibitors.

[0007] According to one embodiment of the present invention, the base oil has a pour point of less than or equal to -35°C; and / or, the base oil comprises one or more of poly-α-olefins, paraffinic oils, naphthenic oils, synthetic ester oils, and alkylnaphthalenes.

[0008] According to one embodiment of the present invention, the base oil comprises 70-89 parts by weight, the thickener comprises 6-20 parts by weight, the antioxidant comprises 0.5-2 parts by weight, the lubricant comprises 1-10 parts by weight, the extreme pressure anti-wear agent comprises 0.1-5 parts by weight, and the rust and corrosion inhibitor comprises 0.1-3 parts by weight.

[0009] According to one embodiment of the present invention, the thickener comprises the reaction product of an organic acid and lithium hydroxide monohydrate, wherein the organic acid comprises 12-hydroxystearic acid and / or stearic acid.

[0010] According to one embodiment of the present invention, the antioxidant includes amine antioxidants and / or phenolic antioxidants, wherein the amine antioxidants include one or more of diphenylamine, p-phenylenediamine, N-phenyl-α-naphthylamine, dialkyldiphenylamine, and phenothiazine, and the phenolic antioxidants include one or more of p-cresol, naphthol, diisobutyl-p-cresol, 2,6-di-tert-butyl-p-cresol, and trimethylphenol.

[0011] According to one embodiment of the present invention, the lubricant includes a solid lubricant, which includes one or more of molybdenum disulfide, boron nitride, graphite, cyanuric acid complex, polytetrafluoroethylene, and organomolybdenum.

[0012] According to one embodiment of the present invention, the extreme pressure anti-wear agent comprises a sulfur-phosphorus type zinc-free liquid additive, wherein the sulfur-phosphorus type zinc-free liquid additive comprises one or more of sulfurized olefin cottonseed oil, sulfurized isobutylene, phosphate ester, phosphate, thiophosphate ester, thiophosphate, thiophosphate amine salt, phosphate ester amine salt, thiocarbamate, and aminothioester.

[0013] According to one embodiment of the present invention, the rust and corrosion inhibitor is selected from one or more of benzotriazole derivatives, thiadiazole derivatives, petroleum sulfonates, and nonylnaphthalene sulfonates.

[0014] According to one embodiment of the present invention, the oil separation rate of the grease composition after being kept at 40℃±0.1℃ for 168h is greater than or equal to 2%.

[0015] In another aspect, the present invention provides a method for preparing a lubricating grease composition, comprising the following steps: adding the base oil, the raw material of the thickener, and water into a reaction vessel, heating to 80°C–90°C, and stirring until homogeneous; then heating to 130°C–140°C to carry out a saponification reaction; then continuing to heat to 145°C–150°C, and opening the pressure relief valve of the reaction vessel to release pressure and dehydrate; then closing the pressure relief valve of the reaction vessel, heating to 205°C–215°C, and holding at that temperature for 5 min–15 min; then cooling to 70°C–80°C, adding the additive, and stirring for 1.5 h–2 h to obtain the lubricating grease composition.

[0016] The implementation of this invention has at least the following beneficial effects: by using a kinematic viscosity of 20-165 mm at 40℃±0.1℃... 2 The grease composition, consisting of base oil, thickener, and additives, uses a low-viscosity base oil with a suitable viscosity range and a rationally compounded additive composition. This improves the oil separation rate and fluidity of the grease composition. Even at low temperatures, the grease composition can maintain a high oil separation rate and good fluidity. It can effectively solve the problems of pseudo-Burlman indentation and fretting corrosion wear in rolling bearings under micro-vibration environments, reduce the wear degree of bearings under micro-vibration environments, and extend the service life of bearings. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. 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.

[0018] This invention provides a lubricating grease composition comprising a base oil, a thickener, and additives. The base oil has a kinematic viscosity of 20–165 mmHg at 40°C ± 0.1°C. 2 / s; Additives include one or more of antioxidants, lubricants, extreme pressure anti-wear agents, and rust and corrosion inhibitors.

[0019] According to the inventors' research, greases prepared using low-viscosity base oils, while exhibiting good fluidity, have excessively high oil separation rates. Rapid base oil loss negatively impacts grease life. Conversely, greases prepared using high-viscosity base oils have lower oil separation rates, making it difficult for the base oil to return and replenish lubrication in the bearing's friction contact area. This results in significant bearing wear under low-amplitude reciprocating motion testing conditions. However, in the grease composition system described in this invention, selecting a low-viscosity base oil with a suitable viscosity range allows the grease composition to achieve a higher oil separation rate and better fluidity. During reciprocating motion of the bearing friction components, the low-viscosity oil more easily returns to replenish the lubricating film, resulting in a higher oil separation rate. Under reciprocating motion conditions, this reduces the development of pseudo-Burlman indentation and fretting corrosion wear. Furthermore, the rationally formulated additive composition synergistically enhances the lubrication effect of the grease composition on the bearing, thereby reducing bearing wear under micro-vibration conditions and extending bearing life.

[0020] In addition, the above-mentioned grease composition also has good low-temperature performance. It can maintain a high oil separation rate and good fluidity at low temperatures, so that the grease composition can still maintain good lubrication at low temperatures, suppress pseudo-Burlman indentation and fretting corrosion wear of rolling bearings under micro-vibration environment, reduce the wear degree of bearings under micro-vibration environment, and extend the service life of bearings.

[0021] For example, the kinematic viscosity of the base oil at 40℃±0.1℃ can be 20 mm. 2 / s, 50mm 2 / s, 80mm 2 / s, 110mm 2 / s, 140mm 2 / s, 165mm 2 / s or a range consisting of either / s or any two of them.

[0022] In some embodiments, the pour point of the base oil may be less than or equal to -35°C, further improving the low-temperature performance of the grease composition. The grease composition has a large oil separation rate and good fluidity at low temperatures, which is conducive to reflux and improves the lubrication effect of the grease composition at low temperatures. It also inhibits pseudo-Burlman indentation and fretting corrosion wear of rolling bearings under micro-vibration conditions, reduces the wear degree of bearings under micro-vibration conditions, and extends the service life of bearings.

[0023] In addition, the base oil may include one or more of poly-α-olefin, paraffinic oil, naphthenic oil, synthetic ester oil, and alkylnaphthalene. The synthetic ester oil may include pentaerythritol ester. In some embodiments, by weight, the base oil comprises 70-89 parts, the thickener 6-20 parts, the antioxidant 0.5-2 parts, the lubricant 1-10 parts, the extreme pressure anti-wear agent 0.1-5 parts, and the rust and corrosion inhibitor 0.1-3 parts.

[0024] Specifically, by weight, the base oil can be in the range of 70, 75, 80, 85, 89 parts or any two of these; the thickener can be in the range of 6, 10, 14, 18, 20 parts or any two of these; the antioxidant can be in the range of 0.5, 1, 1.5, 2 parts or any two of these; the lubricant can be in the range of 1, 3, 5, 7, 10 parts or any two of these; the extreme pressure anti-wear agent can be in the range of 0.1, 1, 2, 3, 4, 5 parts or any two of these; and the rust and corrosion inhibitor can be in the range of 0.1, 0.5, 1, 1.5, 2, 2.5, 3 parts or any two of these.

[0025] In some embodiments, the base oil in the grease composition may be 70% to 89% by mass, for example, a range of 70%, 75%, 80%, 85%, 89%, or any two of these.

[0026] In some embodiments, the mass percentage of thickener in the grease composition can be 0.5% to 2%, for example, 6%, 10%, 14%, 18%, 20%, or any combination thereof. This is beneficial for the grease composition to have a high oil separation rate, reducing bearing wear. At the same time, it can also maintain a suitable consistency of the grease composition, which is beneficial for loading the grease composition into the bearing and preventing leakage of the grease composition, thereby maintaining the lubrication effect on the bearing.

[0027] In some embodiments, the antioxidant content in the grease composition may be 0.5% to 2% by mass, for example, a range of 0.5%, 1%, 1.5%, 2%, or any two of these.

[0028] In some embodiments, the mass percentage of lubricant in the grease composition may be 1% to 10%, for example, a range of 1%, 3%, 5%, 7%, 10%, or any two of these.

[0029] In some embodiments, the mass percentage of extreme pressure anti-wear agent in the grease composition may be 0.1% to 5%, for example, a range of 0.1%, 1%, 2%, 3%, 4%, 5%, or any combination thereof.

[0030] In some embodiments, the mass percentage of the rust and corrosion inhibitor in the grease composition may be 0.1% to 3%, for example, a range of 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or any two of these.

[0031] In some embodiments, the thickener may include the reaction product of an organic acid and lithium hydroxide monohydrate. The organic acid may include 12-hydroxystearic acid and / or stearic acid. The thickener disperses and forms a structural framework in the base oil, allowing the base oil to be adsorbed and fixed within the structural framework, thereby forming a semi-solid grease composition. This facilitates installation into bearings and reduces bearing wear and other problems. In some embodiments, the antioxidant includes amine antioxidants and / or phenolic antioxidants. Amine antioxidants include one or more of diphenylamine, p-phenylenediamine, N-phenyl-α-naphthylamine, dialkyldiphenylamine, and phenothiazine. Phenolic antioxidants include one or more of p-cresol, naphthol, diisobutyl-p-cresol, 2,6-di-tert-butyl-p-cresol, and trimethylphenol. These antioxidants can prevent the lubricating oil from undergoing oxidation during storage and use, thereby improving its performance.

[0032] In some embodiments, the lubricant includes a solid lubricant, which includes one or more of molybdenum disulfide, boron nitride, graphite, cyanuric acid complex, polytetrafluoroethylene, and organic molybdenum, and is capable of improving the load-carrying capacity of the grease composition and improving boundary lubrication conditions.

[0033] Specifically, organic molybdenum may include molybdenum thiocarbamate, specifically molybdenum dialkyl dithiocarbamate.

[0034] In some embodiments, the extreme pressure anti-wear agent may include a sulfur-phosphorus type zinc-free liquid additive, which includes one or more of sulfurized olefin cottonseed oil, sulfurized isobutylene, phosphate ester, phosphate, thiophosphate ester, thiophosphate, thiophosphate amine salt, phosphate ester amine salt, thiocarbamate, and aminothioester.

[0035] Phosphates may include ammonium phosphates.

[0036] Among them, sulfur-containing extreme pressure anti-wear agents have good oil solubility and extreme pressure properties, which can significantly improve the load resistance of grease compositions, while phosphorus-containing extreme pressure anti-wear agents have high anti-wear ability and can effectively prevent wear on bearing surfaces under medium load conditions.

[0037] Specifically, thiophosphates can include alkyl zinc thiophosphate.

[0038] In some embodiments, the rust and corrosion inhibitor is selected from one or more of benzotriazole derivatives, thiadiazole derivatives, petroleum sulfonates, and nonylnaphthalene sulfonates, and has good anti-corrosion, lubrication, and stability.

[0039] Specifically, petroleum sulfonates may include calcium petroleum sulfonate.

[0040] In the embodiments of the present invention, unless otherwise specified, the base oil, antioxidant, lubricant, extreme pressure anti-wear agent, rust and corrosion inhibitor and other materials used can be commercially available. For example, the base oil (poly-α-olefin) used may include PAO10 and / or PAO40.

[0041] In some embodiments, the oil separation rate of the grease composition after being kept at 40°C ± 0.1°C for 168 hours can be greater than or equal to 2%. Specifically, the oil separation rate of the grease composition after being kept at 40°C ± 0.1°C for 168 hours can be 2% to 6%, for example, a range of 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6% or any two of these. This range facilitates the return flow to replenish the lubricating film without causing the base oil to be lost too quickly and affecting the life of the grease composition.

[0042] In this embodiment of the invention, the oil separation rate of the grease composition can be measured with reference to the IP121 standard.

[0043] The present invention also provides a method for preparing a lubricating grease composition, comprising the following steps: adding base oil, thickener raw materials and water to a reaction vessel, heating to 80℃~90℃, and stirring evenly; then heating to 130℃~140℃ for saponification reaction; then continuing to heat to 145℃~150℃, and opening the pressure relief valve of the reaction vessel for depressurization and dehydration; then closing the pressure relief valve of the reaction vessel, heating to 205℃~215℃, holding at that temperature for 5min~15min; then cooling to 70℃~80℃, adding additives, and stirring for 1.5h~2h to obtain the lubricating grease composition.

[0044] Specifically, the base oil, thickener, and water are added to the reaction vessel. The temperature after heating can be within the range of 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, or any combination thereof. After stirring evenly, the temperature after heating (i.e., the saponification reaction temperature) can be within the range of 130℃, 132℃, 134℃, 136℃, 138℃, 140℃, or any combination thereof. The pressure relief valve of the reaction vessel is closed, and the temperature continues to rise at a rate of 4℃~5℃ / min. The final temperature can be 205℃, 207℃, 2... The temperature range is 0.09℃, 211℃, 213℃, 215℃ or any two of these ranges; the constant temperature holding time can be 5 min, 7 min, 9 min, 11 min, 13 min, 15 min or any two of these ranges; the temperature after cooling can be 70℃, 72℃, 74℃, 76℃, 78℃, 80℃ or any two of these ranges; after adding the additive, the stirring time can be 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2 h or any two of these ranges.

[0045] In this embodiment of the invention, the anti-wear performance of the grease composition under micro-vibration conditions can be determined by testing with a high-frequency linear oscillation (SRV) tester, bearing wear test, and riffel-test.

[0046] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be further described below in conjunction with specific embodiments.

[0047] Example 1:

[0048] 1. Preparation of grease compositions

[0049] 10800g of base oil (kinematic viscosity 100mm at 40℃) 2 1046g of dodecyl stearic acid (pour point -38℃), 154g of lithium hydroxide monohydrate, and 700g of water were added to a reaction vessel and heated to 80℃, stirring until homogeneous. Then, the temperature was raised to approximately 135℃ and held for 45 minutes. The temperature was further increased to 146℃ while simultaneously depressurizing and dehydrating. After depressurization, the pressure relief valve was closed, and the temperature was rapidly increased to 210℃ at a rate of 4℃ / min and held for 10 minutes. The temperature was then slowly lowered to 80℃, additives were added, and the mixture was stirred for 1.5 hours. The mixture was then removed from the vessel and ground to obtain the grease composition. The types of additives and the mass ratio of each component in the grease composition are shown in Table 1. The rust inhibitor was calcium petroleum sulfonate.

[0050] 2. Tests on the oil separation rate and anti-wear performance of the grease composition under micro-vibration conditions.

[0051] (1) Oil separation rate

[0052] Following the standard method described in IP121, the oil separation rate of the grease composition was tested after being kept in an oven at 40°C for 168 hours. A separation rate between 2% and 6% under micro-vibration conditions provides good lubrication.

[0053] (2) High-frequency linear oscillation (SRV) tester

[0054] According to the standard method of ASTM D7594, the test was conducted using a high-frequency linear oscillation (SRV) tester under high-Hertz contact pressure and high-frequency linear oscillation motion. The test conditions were: load 100N, temperature 50℃, amplitude 0.3mm, frequency 50Hz, and time 4h. The size of the wear scar on the steel ball after the test (i.e., the average wear scar diameter in Table 2) was measured.

[0055] (3) Bearing wear test

[0056] Following the standard method of ASTM D4170, tests were conducted using a Fevre testing machine (Falex F-1581 fretting wear tester). Two thrust ball bearings fitted with test grease were subjected to oscillation motion at a radius of 0.21 (12°), an oscillation frequency of 30.0 Hz (1800 cpm), a load of 2450 N (550 lbf), and room temperature for 22 hours. The average mass loss of the upper and lower bearing races after the test was measured (i.e., the upper and lower bearing race mass losses shown in Table 2). Generally, a bearing race mass loss of no more than 20 mg is considered to indicate good lubrication.

[0057] (4) Riffel Test

[0058] The bench test simulated the bearing under vibration when it was stationary or under limited rotation, resulting in pseudo-Burlman indentation and fretting corrosion wear. The four-corner contact ball bearing was subjected to an alternating load of 70 kN, and a 1% NaCl aqueous solution was injected into the bearing at a flow rate of 6 mL / min. After the test, the ripple wear depth of the bearing inner ring was analyzed by a profilometer (i.e., the maximum ripple depth and average ripple depth in Table 2). When the maximum ripple wear depth was less than 10 μm and the average ripple wear depth was less than 3 μm, it indicated that the performance of the grease composition was good.

[0059] Comparative Example 3:

[0060] The difference from Example 1 is that no thickener is added during the preparation of the grease composition, as detailed below:

[0061] 10800g of base oil (kinematic viscosity 100mm at 40℃) 2Add 700g of water and a grease (with a pour point of -38℃) to a reactor, heat to 80℃, and stir until homogeneous. Then heat to approximately 135℃ and hold for 45 minutes. Continue heating to 146℃ while simultaneously depressurizing and dehydrating. After depressurization, close the pressure relief valve, rapidly heat to 210℃ at a rate of 4℃ / min and hold for 10 minutes. Slowly cool to 80℃, add additives, and stir for 1.5 hours. Remove from the reactor and grind to obtain the lubricating grease composition.

[0062] Examples 2 to 9, and Comparative Examples 1 to 3: The difference from Example 1 is that the base oil and its kinematic viscosity and pour point, solid lubricant, extreme pressure anti-wear agent, thickener, etc. are different, as shown in Tables 1, 2, and 3. Except for the differences shown in Tables 1, 2, and 3, all other conditions are the same.

[0063] In addition, the oil separation rate and anti-wear performance test results of the grease compositions prepared in each embodiment and comparative example under micro-vibration conditions are shown in Table 4.

[0064] Table 1

[0065]

[0066] Table 2

[0067]

[0068] Table 3

[0069]

[0070]

[0071] Table 4

[0072]

[0073] Compared to Comparative Examples 1 and 2, the kinematic viscosity of the base oils in Examples 1 to 7 was 20–165 mm. 2 / s, with a base oil pour point less than or equal to -35℃, which helps to improve the oil separation rate of the grease composition, reduce the degree of bearing wear, result in smaller bearing wear scar diameter, less mass loss of bearing housing, and smaller bearing ripple wear depth, and has better anti-wear performance under micro-vibration conditions.

[0074] Compared to Examples 3 and 4, the solid lubricant in Example 1 includes organic molybdenum (molybdenum thiocarbamate), which is beneficial to further improve the oil separation rate of the grease composition, reduce the degree of bearing wear, reduce the bearing wear scar diameter, reduce the mass loss of the bearing housing, reduce the depth of bearing ripple wear marks, and have better anti-wear performance under micro-vibration conditions.

[0075] Furthermore, although Example 6 can improve the oil separation rate of the grease composition, it contains too little thickener, and the grease composition is a semi-fluid grease, which is not conducive to being installed in the bearing.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A grease composition characterized in that, comprising a base oil, a thickening agent and an additive, the base oil having a kinematic viscosity at 40°C ± 0.1°C of 20 to 165 mm 2 / s; the additive comprising one or more of an antioxidant, a lubricant, an extreme pressure antiwear agent, an antirust and anticorrosion agent.

2. The grease composition according to claim 1, wherein, the base oil has a pour point of -35℃ or less; and / or, the base oil comprises one or more of poly-alpha-olefins, paraffin base oils, naphthenic base oils, synthetic ester oils, alkyl naphthalenes.

3. The grease composition of claim 1, wherein the base oil is 70-89 parts by mass, the thickening agent is 6-20 parts by mass, the antioxidant is 0.5-2 parts by mass, the lubricant is 1-10 parts by mass, the extreme pressure anti-wear agent is 0.1-5 parts by mass, and the rust and corrosion inhibitor is 0.1-3 parts by mass.

4. The grease composition of claim 1, wherein the thickening agent comprises a reaction product of an organic acid and lithium monohydrate, and the organic acid comprises 12-hydroxystearic acid and / or stearic acid.

5. The grease composition of claim 1, wherein the antioxidant comprises one or more of an amine antioxidant and / or a phenolic antioxidant, the amine antioxidant comprises one or more of diphenylamine, p-phenylenediamine, N-phenyl-alpha-naphthylamine, dialkyldiphenylamine, phenothiazine, and the phenolic antioxidant comprises one or more of p-cresol, naphthol, diisobutyl p-cresol, 2,6-di-tert-butyl p-cresol, and trimethylphenol.

6. The grease composition of claim 1, wherein the lubricant comprises a solid lubricant, and the solid lubricant comprises one or more of molybdenum disulfide, boron nitride, graphite, cyanuric acid complex, polytetrafluoroethylene, and organic molybdenum.

7. The grease composition of claim 1, wherein the extreme pressure anti-wear agent comprises a sulfur-phosphorus type zinc-free liquid additive, and the sulfur-phosphorus type zinc-free liquid additive comprises one or more of sulfurized olefin cottonseed oil, sulfurized isobutylene, phosphate ester, phosphate, thiophosphate ester, thiophosphate, thiophosphate amine salt, phosphate amine salt, thioaminoformate, and aminothioester.

8. The grease composition of claim 1, wherein the rust and corrosion inhibitor is selected from one or more of benzotriazole derivatives, thiadiazole derivatives, petroleum sulfonate, and nonyl naphthalene sulfonate.

9. The grease composition of claim 1, wherein the grease composition has a separation rate of 2% or more after being kept at 40℃±0.1℃ for 168h.

10. A process for the preparation of the grease composition according to any one of claims 1 to 9, characterized in that, comprises the following steps: adding the base oil, raw materials of the thickening agent, and water into a reaction kettle, heating to 80-90℃, and stirring until uniform; then heating to 130-140℃ to perform a saponification reaction; then continuing to heat to 145-150℃, and opening a pressure relief valve of the reaction kettle to perform pressure relief and dehydration; then closing the pressure relief valve of the reaction kettle, heating to 205-215℃, and maintaining the temperature for 5-15min; then cooling to 70-80℃, adding the additives into the reaction kettle, and stirring for 1.5-2h to obtain the grease composition.

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