A special grease for wind turbine gearboxes

Abstract

The present application belongs to the technical field of lubricating grease, and particularly relates to a special lubricating grease for wind power gearboxes. The present application is composed of a synthetic base oil, a composite calcium sulfonate base grease, a stimulus-responsive polyionic liquid grafted Ti3C2T x MXene core-shell nanoplate, phosphorus-sulfur-molybdenum-containing extreme pressure anti-wear agent, antioxidant, adhesive polymer and modified boron nitride nanodispersed phase, and has the advantages that by constructing a polyionic liquid shell layer covering a MXene core with a heat-induced shrinkage-expansion reversible conversion characteristic and designing a phosphorus-sulfur-molybdenum-containing extreme pressure anti-wear agent, extreme pressure anti-wear is realized in a full-temperature-domain cascade response; by enhancing the network structure of the thickening agent through the boron nitride nanodispersed phase, the colloidal stability is improved.

Description

Technical Field

[0001] This invention belongs to the field of lubricating grease technology, specifically relating to a special lubricating grease for wind turbine gearboxes. Background Technology

[0002] Wind turbine gearboxes operate under conditions of low-speed, heavy-load, frequent start-stop, alternating impact loads, and temperature fluctuations. Micropitting on gear meshing surfaces typically manifests as gray spots on the tooth surface, localized spalling, and fatigue crack initiation, subsequently leading to gear vibration, increased noise, and decreased transmission efficiency. Existing wind turbine gearbox lubrication systems primarily use gear oil, typically improving anti-wear and anti-micropitting capabilities by increasing base oil viscosity and adding sulfur-phosphorus extreme pressure agents, molybdenum-based anti-wear agents, or antioxidants. Existing patent CN105838483A discloses an anti-wear wind turbine gear oil and its preparation method. This gear oil is composed of monoalkenyl succinimide, alkylbenzene sulfonate calcium, dioctyl diphenylamine, thiomethylphenol, anti-wear agents, and base oil, and specifies that wind turbine gearbox oils need to possess anti-micropitting properties. This solution belongs to a liquid gear oil system, primarily relying on oil-soluble extreme pressure anti-wear additives to inhibit pitting, without addressing the grease thickening structure, rapid interface enrichment under alternating loads, or the regulation of the additive activity temperature window. However, existing technologies still have the following shortcomings:

[0003] (1) Delayed response of micropitting protection. The formation of micropitting is accompanied by the instantaneous rupture of the oil film and direct metal-to-metal contact. However, existing additives are pre-dispersed in the grease and rely on tribochemical reactions to form a film. Irreversible microscopic damage has already occurred on the tooth surface before the protective film is formed. This "post-event protection" mode is difficult to effectively inhibit the initiation of initial micropitting pits.

[0004] (2) Inherent limitations of the base oil-additive two-phase system. Under long-term alternating loads, greases undergo repeated shearing and relaxation, leading to frequent problems such as thickener network structure destruction, additive-base oil phase separation, and uneven local additive concentration. Existing greases have insufficient colloidal stability, making it difficult to match the 20-year design life of wind turbine generators, and they typically need to be replaced every 3–5 years.

[0005] (3) The active temperature window of extreme pressure anti-wear agents does not match the operating conditions. The operating temperature range of wind turbine gearboxes is wide, from -30℃ to 150℃, but the active temperature window of conventional extreme pressure anti-wear agents is narrow: at low temperatures, the additives are "dormant", and lubrication mainly relies on the base oil film, which has limited load-bearing capacity; at high temperatures, the reaction is too fast, which leads to the embrittlement and peeling of the reaction film, which becomes a source of wear.

[0006] To address these issues, this invention proposes a special grease for wind turbine gearboxes with dynamic adaptive lubrication and protection capabilities. Summary of the Invention

[0007] This invention provides a special lubricating grease for wind turbine gearboxes, aiming to solve the problems of existing technologies. The lubricating grease is composed of synthetic base oil, complex calcium sulfonate base grease, and stimuli-responsive polyionic liquid grafted Ti3C2T. x It consists of MXene core-shell nanosheets, a phosphorus-sulfur-molybdenum extreme pressure anti-wear agent, an antioxidant and rust-preventive composition, an adhesive polymer, and a boron nitride nano-dispersed phase at the friction interface.

[0008] A special lubricating grease for wind turbine gearboxes, the technical solution of which is as follows: S1: PAO8 and alkylnaphthalene AN30 are mixed evenly at a mass ratio of 4:1 to obtain base oil. The base oil and high-alkalinity synthetic calcium sulfonate are added to the reactor and stirred evenly at 60℃~80℃. Deionized water and glacial acetic acid are added for conversion, and the residual acid value is ≤0.5mgKOH / g. The characteristic peak of calcite-type CaCO3 is confirmed by XRD. 12-hydroxystearic acid, boric acid and calcium hydroxide are added, and the mixture is saponified and dehydrated to obtain the complex calcium sulfonate base ester. S2: Ti3AlC2MAX phase ceramic powder and LiF were added to HCl solution and etched by stirring; 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, azobisisobutyronitrile initiator, and N,N'-methylenebisacrylamide were added, and PIL-MXene was obtained by polymerization under nitrogen; Fe3O4 was modified with silane, Fe3O4 nanoparticles were mixed in anhydrous ethanol, ultrasonically dispersed, modified with KH570, and then washed and dried to constant weight; then compounded with PIL-MXene to prepare PIL-MXene concentrated slurry; S3: Polyisobutylene succinic anhydride, toluene, C12 long-chain alkyl phosphate, and p-toluenesulfonic acid are added to a container for esterification. After vacuum distillation, phosphorus pentasulfide and sulfur powder are added to the residue for sulfidation. Molybdenum dialkyldithiocarbamate is added and the mixture is reacted under nitrogen protection at 80℃~100℃ for 2~4h. After the reaction is completed, the insoluble matter is removed by filtration, and the filtrate is concentrated and then vacuum devolatilized to obtain a phosphorus-sulfur-molybdenum extreme pressure anti-wear agent. S4: Take hexagonal boron nitride nanosheets, disperse them in anhydrous ethanol, add γ-aminopropyltriethoxysilane, control the pH at 4.5-5.5, ultrasonically disperse for 30 minutes, react at 60℃-80℃ for 4-6 hours; centrifuge and wash, vacuum dry at 60℃ for 12 hours to obtain modified hexagonal boron nitride nanosheets; cool the base grease to 80℃-90℃, add phosphorus-sulfur-molybdenum extreme pressure anti-wear agent; cool to 60℃-80℃, add PIL-MXene concentrated slurry, modified h-BN, adhesive polymer polyisobutylene PIB, 4,4'-dioctyl diphenylamine antioxidant, rust inhibitor calcium petroleum sulfonate, and metal deactivator benzotriazole derivative T551; disperse at 4000 rpm for 20 minutes, grind and defoam; adjust the amount of base oil added so that the total mass of the obtained grease is 100 parts.

[0009] Further, the conversion described in step S1 specifically involves introducing CO2 to convert calcium carbonate crystals; controlling the conversion temperature at 70℃~90℃ and the conversion time at 60~120min.

[0010] Further, the saponification and dehydration refining process described in step S1 specifically involves saponification at 95℃~110℃ for 60~120 minutes; heating to 150℃~180℃ for dehydration refining; and cooling to below 90℃.

[0011] Further, the stirring etching described in step S2 specifically involves stirring and etching in a 35°C water bath for 24 hours; centrifuging and washing at 3500 rpm for 5 minutes until the pH of the supernatant is 6; collecting the precipitate and dispersing it in deionized water; ultrasonically peeling with nitrogen gas at 300W for 1 hour; and centrifuging at 3500 rpm for 1 hour to collect the supernatant.

[0012] Furthermore, the vulcanization reaction described in step S3 specifically involves heating to 120°C–130°C and stirring the vulcanization reaction for 3–4 hours.

[0013] Furthermore, the grinding and degassing described in step S4 specifically involves grinding three times using a three-roll mill, with a gap of 50 μm for the first time, 30 μm for the second time, 15 μm for the third time, and finally degassing under vacuum at -0.095 MPa for 30 minutes.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The thermal shrinkage-expansion response time of the PIL-g-MXene core-shell structure of this invention is faster than that of traditional tribochemical reaction, and can release anti-wear components at the moment of oil film rupture, thus blocking the formation of micropitting corrosion from the source.

[0015] (2) The present invention uses a phosphorus-sulfur-molybdenum extreme pressure anti-wear agent to avoid the dormancy or over-reaction problems of traditional extreme pressure anti-wear agents.

[0016] (3) The composite calcium sulfonate base grease of the present invention provides high dropping point, water resistance and basic extreme pressure performance; boron nitride nano-dispersed phase provides low shear lamellar and nano-interstitial effects; adhesive polymer improves grease film retention. After multi-component synergy, it can improve the structural retention ability and resistance to micropitting corrosion after long-term shearing. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the preparation process of a special lubricating grease for wind turbine gearboxes.

[0018] Figure 2 This is a morphological image of the test result from Experiment Example 1.

[0019] Figure 3 This is a characterization diagram of the test in Experiment Example 2.

[0020] Figure 4 The XRD pattern is from test example 3.

[0021] Figure 5 The image shows the FTIR functional group characterization results from Experiment Example 4. Detailed Implementation

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] The preferred embodiments of the present invention are described in detail below; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention. Figure 1 The flowchart shown illustrates the preparation process of a special lubricating grease for wind turbine gearboxes. The specific preparation method is as follows: 1. Preparation of calcium sulfonate base lipid High-alkalinity calcium sulfonate is a colloidal system composed of numerous calcium carbonate particles encapsulated in calcium sulfonate surfactant micelles. Upon addition of deionized water and glacial acetic acid, the acetic acid reacts with calcium carbonate to produce calcium acetate and CO2, disrupting the original calcium carbonate micelle structure. Calcium acetate hydrolyzes under stirring, recombining with free calcium ions, sulfonate ions, and calcium carbonate ions in the system to form amorphous calcium carbonate encapsulating the calcium sulfonate molecular layer in a composite micelle. When the conversion reaction proceeds fully, the resulting micelles are spherical or short rod-shaped. 12-hydroxystearic acid undergoes a neutralization saponification reaction with calcium hydroxide to produce 12-hydroxystearate, a long-chain fatty acid calcium soap. Boric acid reacts with calcium ions under alkaline conditions to produce calcium metaborate and calcium borate. Boron atoms have a three- or four-coordinate structure, which can form rigid bridging bonds. The fatty acid calcium soap and calcium carbonate / calcium borate micelles form a mixed soap fiber network through physical entanglement and chemical bonding. These fibers intertwine to form a three-dimensional framework, encapsulating the base oil within the fiber gaps.

[0024] 2. Preparation of PIL-modified MXene composite nanosheets Using Ti3AlC2MAX phase ceramic as a precursor, HF is generated in situ via the reaction of LiF and HCl. HF selectively etches away the Al atomic layers, leaving a layered Ti3C2T structure. x During the etching process, Li +Interlayer embedding facilitates interlayer spacing expansion. Ultrasonic exfoliation under nitrogen protection utilizes the cavitation effect of ultrasound to generate shock waves and microjets, overcoming interlayer van der Waals forces and exfoliating multilayered MXene into few-layer (≤5-layer) nanosheets. Centrifugation yields a few-layered MXene colloid with uniform lateral dimensions. Using 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide as the monomer, AIBN as the thermal initiator, and N,N'-methylenebisacrylamide as the crosslinking agent, the abundant –OH groups on the MXene surface interact with the monomer and initiator, initiating in-situ free radical polymerization of the monomer on the MXene surface to form a covalently grafted polyionic liquid shell. The polyionic liquid exhibits thermotropic shrinkage-stretching properties. At room temperature, ionic liquid segments form a contracted state due to electrostatic interactions and hydrogen bond networks. As the temperature rises, thermal motion intensifies, hydrogen bonds dissociate, and the segment conformation transforms into an extended state. This rapid transformation enables instantaneous sensing of frictional heat. Under ultrasonic irradiation, Fe3O4 nanoparticles enter the network structure of the polyionic liquid shell and the interlayer voids of MXene through electrostatic adsorption and physical embedding. Fe3O4 possesses both rigidity and magnetism, and can be released to the friction interface when the polyionic liquid shell extends, enabling rolling repair and polishing of slightly worn surfaces. It also participates in tribochemical reactions to generate a Fe-containing composite protective film.

[0025] When the gear meshing surface experiences boundary lubrication failure and localized instantaneous temperature rise, the polyionic liquid shell rapidly transitions from a contracted state to an expanded state, simultaneously releasing MXene nanosheets, ionic liquid fragments, and Fe3O4 particles. The exposed MXene, with its extremely low interlaminar shear stress, forms a physical insulating film; the cations and anions in the ionic liquid undergo physical adsorption and tribochemical reactions with the metal surface, generating a composite protective film in situ; and the Fe3O4 particles repair the micro-protrusions.

[0026] 3. Preparation of phosphorus-sulfur-molybdenum-containing extreme pressure anti-wear agent Polyisobutylene succinic anhydride (PIBSA) is a high-molecular-weight ashless dispersant with a flexible molecular chain that facilitates subsequent grafting reactions. The active hydrogen and carbonyl groups on its succinimide structure can participate in esterification and amidation reactions, providing reaction sites for grafting. The carboxyl groups on the PIBSA backbone undergo esterification with the hydroxyl groups of C12 long-chain alkyl phosphates under acid catalysis, forming covalent ester bonds. p-Toluenesulfonic acid, as a strong acid catalyst, promotes the esterification equilibrium to the right. The long-chain alkyl groups impart good oil solubility to the molecule, while the phosphate groups exhibit strong polarity, allowing it to form a physical adsorption film with the tooth surface metal at low temperatures. The adsorption film exists due to intermolecular forces and does not require tribochemical activation, thus providing basic load-bearing capacity at low temperatures. Phosphorus pentasulfide undergoes a sulfidation reaction with existing alkoxy or hydroxyl groups in the molecule to generate a thiophosphate structure. The addition of sulfur powder regulates the degree of sulfidation and prevents excessive cross-linking. Thiophosphates exhibit high reactivity with iron-based metals at medium temperatures, decomposing through tribochemical processes and reacting with the metal to form a composite reaction film. This film possesses both anti-wear and extreme pressure properties, and its formation rate is moderate, preventing embrittlement due to excessively rapid film formation. The molybdenum atoms in the dialkyldithiocarbamate molybdenum can coordinate with heteroatoms such as S, O, and N on the phosphorus-sulfur-molybdenum extreme pressure anti-wear agent backbone through coordinate bonds, forming a stable graft structure. The coordination reaction is carried out under mild conditions to avoid the thermal decomposition of MoDTC.

[0027] 4. Preparation of lubricating grease Hexagonal boron nitride has an inert surface and poor affinity for base oils and soap fibers, making it prone to aggregation. γ-aminopropyltriethoxysilane undergoes a hydrolytic condensation reaction with the surface groups of hexagonal boron nitride. The ethoxy group of the silane hydrolyzes to generate Si-OH, which then condenses with the active hydrogen on the surface of hexagonal boron nitride, thereby grafting propylamino groups onto the surface of hexagonal boron nitride. The grafted hexagonal boron nitride surface possesses lipophilic organic segments, significantly improving its compatibility with base oils. Simultaneously, the amine groups can form hydrogen bonds with the carboxyl groups in the thickener, promoting uniform dispersion. The three-roll mill utilizes the immense shearing force between three counter-rotating rollers to break down agglomerates in the grease, reducing the particle size of the additives to the nanoscale. The three-stage grinding process achieves graded refinement, ensuring the uniformity and fineness of the grease. The resulting grease is used in gearbox bearings or as a sealing grease.

[0028] Example 1 Table 1 Raw Material Information Table

[0029] S1: Preparation of Complex Calcium Sulfonate Base Ester PAO8 and alkylnaphthalene AN30 were mixed evenly at a mass ratio of 4:1 to obtain a base oil. 62 parts of the base oil and 25 parts of high-alkalinity synthetic calcium sulfonate were added to a reactor and stirred evenly at 70℃. 5 parts of deionized water and 1.5 parts of glacial acetic acid were added, and CO2 was introduced to convert the calcium carbonate crystal form. The conversion temperature was controlled at 80℃ for 90 minutes, with a residual acid value ≤0.5 mg KOH / g. Samples were taken and XRD was used to confirm the characteristic peaks of calcite-type CaCO3. 2.2 parts of 12-hydroxystearic acid, 1.2 parts of boric acid, and 1.5 parts of calcium hydroxide were added, and saponification was performed at 103℃ for 90 minutes. The temperature was raised to 165℃ for dehydration and refining. The temperature was then lowered to below 90℃ to obtain the composite calcium sulfonate base ester. S2: Preparation of PIL-modified MXene composite nanosheets 2.5 parts by weight of Ti3AlC2MAX phase ceramic powder and 3.5 parts by weight of LiF were added to 19 parts by weight of HCl solution. The mixture was stirred and etched in a water bath at 35°C for 24 hours. After centrifugation at 3500 rpm for 5 minutes until the pH of the supernatant reached 6, the precipitate was collected and dispersed in deionized water. The mixture was then ultrasonically exfoliated under nitrogen at 300W for 1 hour, followed by centrifugation at 3500 rpm for 1 hour. The supernatant was then collected. The monomer 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl) was added. PIL-MXene was obtained by polymerizing 2.5 parts of imine salt, 0.03 parts of azobisisobutyronitrile initiator, and 0.05 parts of N,N'-methylenebisacrylamide under nitrogen atmosphere. Fe3O4 was silane modified by mixing 3 parts of Fe3O4 nanoparticles with 43 parts of anhydrous ethanol, ultrasonically dispersing, adding 1 part of KH570 for modification, and then washing and drying to constant weight. This was then combined with PIL-MXene to obtain a composite stimulus-responsive polyionic liquid grafted with Ti3C2T. x MXene core-shell nanosheets were used to obtain PIL-MXene concentrated slurry; S3: Preparation of phosphorus-sulfur-molybdenum-containing extreme pressure anti-wear agent Add 45 parts of polyisobutylene succinic anhydride, 85 parts of toluene, 20 parts of C12 long-chain alkyl phosphate, and 0.25 parts of p-toluenesulfonic acid to a container for esterification. After vacuum distillation, add 13 parts of phosphorus pentasulfide and 2.5 parts of sulfur powder to the residue, heat to 125°C, and stir for 3.5 hours for vulcanization. Add 20 parts of molybdenum dialkyldithiocarbamate and react under nitrogen protection at 90°C for 3 hours. After the reaction is complete, filter to remove insoluble matter, concentrate the filtrate, and then vacuum devolatilize to obtain a phosphorus-sulfur-molybdenum extreme pressure anti-wear agent. S4: Post-fat treatment Three parts of hexagonal boron nitride nanosheets were dispersed in 90 parts of anhydrous ethanol, and 0.2 parts of γ-aminopropyltriethoxysilane were added. The pH was controlled at 5, and the mixture was ultrasonically dispersed for 30 minutes and reacted at 70℃ for 5 hours. After centrifugation and washing, the mixture was vacuum dried at 60℃ for 12 hours to obtain modified hexagonal boron nitride nanosheets. The base grease was cooled to 85℃, and 3 parts of a phosphorus-sulfur-molybdenum extreme pressure anti-wear agent were added. The mixture was then cooled to 70℃, and 0.75 parts of PIL-MXene concentrated slurry, 0.5 parts of modified h-BN, and 3.2 parts of the adhesive polymer polyisobutylene were added. IB, 0.55 parts of 4,4'-dioctyldiphenylamine antioxidant, 0.3 parts of rust inhibitor calcium petroleum sulfonate, and 0.12 parts of metal deactivator benzotriazole derivative T551; dispersed at 4000 rpm for 20 minutes, then milled three times using a three-roll mill with a gap of 50 μm for the first mill, 30 μm for the second, and 15 μm for the third; finally, degassed under vacuum at -0.095 MPa for 30 minutes; the amount of base oil added was adjusted to obtain a grease with a mass of 100 parts; this grease is used in gearbox bearings or as a sealing grease.

[0030] Example 2 The preparation method is the same as in Example 1, but with the following differences: In step S1: 55 parts base oil, 20 parts high-alkalinity synthetic calcium sulfonate are added to the reactor; 4 parts deionized water and 1 part glacial acetic acid are added; 1.5 parts 12-hydroxystearic acid, 0.5 parts boric acid and 0.8 parts calcium hydroxide are added. In step S2: 2 parts by weight of Ti3AlC2MAX phase ceramic powder and 3 parts by weight of LiF were added to 18 parts by weight of HCl solution; the pH was 5.5; 2 parts by weight of monomer 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imine salt, 0.02 parts by weight of azobisisobutyronitrile initiator, and 0.04 parts by weight of N,N'-methylenebisacrylamide were added; 2 parts by weight of Fe3O4 nanoparticles were mixed in 40 parts by weight of anhydrous ethanol, ultrasonically dispersed, and 0.5 parts by weight of KH570 were added for modification; In step S3: add 40 parts of polyisobutylene succinic anhydride, 80 parts of toluene, 15 parts of C12 long-chain alkyl phosphate, 0.2 parts of p-toluenesulfonic acid, 10 parts of phosphorus pentasulfide and 2 parts of sulfur powder; add 15 parts of molybdenum dialkyldithiocarbamate. In step S4: Take 2 parts of hexagonal boron nitride nanosheets, disperse them in 80 parts of anhydrous ethanol, add 0.1 parts of γ-aminopropyltriethoxysilane, and control the pH at 4.5.

[0031] Example 3 The preparation method is the same as in Example 1, but with the following differences: In step S1: 68 parts of base oil and 30 parts of high-alkalinity synthetic calcium sulfonate are added to the reactor; 6 parts of deionized water and 2 parts of glacial acetic acid are added; 3 parts of 12-hydroxystearic acid, 1.8 parts of boric acid and 2.2 parts of calcium hydroxide are added. In step S2: 3 parts by weight of Ti3AlC2MAX phase ceramic powder and 4 parts by weight of LiF were added to 20 parts by weight of HCl solution; the pH was 6.5; 3 parts by weight of monomer 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imine salt, 0.04 parts by weight of azobisisobutyronitrile initiator, and 0.06 parts by weight of N,N'-methylenebisacrylamide were added; 4 parts by weight of Fe3O4 nanoparticles were mixed in 45 parts by weight of anhydrous ethanol, ultrasonically dispersed, and 1.5 parts by weight of KH570 were added for modification; In step S3: add 50 parts of polyisobutylene succinic anhydride, 90 parts of toluene, 25 parts of C12 long-chain alkyl phosphate, 0.3 parts of p-toluenesulfonic acid, 15 parts of phosphorus pentasulfide and 3 parts of sulfur powder; add 25 parts of molybdenum dialkyldithiocarbamate. In step S4: Take 4 parts of hexagonal boron nitride nanosheets, disperse them in 100 parts of anhydrous ethanol, add 0.3 parts of γ-aminopropyltriethoxysilane, and control the pH at 5.5.

[0032] Example 4 The preparation method is the same as in Example 1, but with the following differences: In step S4: add 2 parts of phosphorus-sulfur-molybdenum extreme pressure anti-wear agent; add 0.3 parts of PIL-MXene concentrated slurry, 0.2 parts of modified h-BN, 2 parts of adhesive polymer polyisobutylene (PIB), 0.3 parts of 4,4'-dioctyldiphenylamine antioxidant, 0.1 parts of rust inhibitor calcium petroleum sulfonate, and 0.05 parts of metal deactivator benzotriazole derivative.

[0033] Example 5 The preparation method is the same as in Example 1, but with the following differences: In step S4: add 4 parts of phosphorus-sulfur-molybdenum extreme pressure anti-wear agent; add 1.2 parts of PIL-MXene concentrated slurry, 0.8 parts of modified h-BN, 4.5 parts of adhesive polymer polyisobutylene (PIB), 0.8 parts of 4,4'-dioctyldiphenylamine antioxidant, 0.5 parts of rust inhibitor calcium petroleum sulfonate, and 0.2 parts of metal deactivator benzotriazole derivative.

[0034] Example 6 The preparation method is the same as in Example 1, but with the following differences: In step S1: Stir evenly at 60℃; control the conversion temperature at 70℃ and convert for 120 minutes; saponify at 95℃ for 120 minutes; raise the temperature to 150℃ for dehydration and refining; In step S3: the temperature is raised to 120℃, and the vulcanization reaction is stirred for 4 hours; the compounding reaction is carried out at 80℃ under nitrogen protection for 4 hours. In step S4: ultrasonic dispersion for 30 minutes, reaction at 60℃ for 6 hours; cooling of the base lipid to 80℃; cooling to 60℃, and adding PIL-MXene concentrate.

[0035] Example 7 The preparation method is the same as in Example 1, but with the following differences: In step S1: Stir evenly at 80℃; control the conversion temperature at 90℃ and convert for 60 minutes; saponify at 110℃ for 60 minutes; raise the temperature to 180℃ for dehydration and refining; In step S3: the temperature is raised to 130℃, and the vulcanization reaction is stirred for 3 hours; the compounding reaction is carried out at 100℃ under nitrogen protection for 2 hours. In step S4: ultrasonic dispersion for 30 minutes, reaction at 80℃ for 4 hours; cooling of the base lipid to 90℃; cooling to 80℃, and adding PIL-MXene concentrate.

[0036] Comparative Example 1 The preparation method of Example 1 is followed, but the phosphorus-sulfur-molybdenum extreme pressure anti-wear agent is not added in step S32. The remaining steps are the same.

[0037] Comparative Example 2 The preparation method is the same as in Example 1, but the calcium sulfonate base ester is not added in step S32. The remaining steps are the same.

[0038] Comparative Example 3 The preparation method is the same as in Example 1, but PIL-modified MXene composite nanosheets are not added in step S42. The remaining steps are the same.

[0039] Comparative Example 4 The preparation method of Example 1 is followed, but the modified hexagonal boron nitride nanosheets in step S42 are not modified; instead, an equal amount of ordinary hexagonal boron nitride nanosheets are used. All other steps are the same.

[0040] Experimental Example 1 The PIL-MXene concentrate prepared in Example 1 was purified by diluting the PIL-MXene / Fe3O4 concentrate with deionized water / anhydrous ethanol at a volume ratio of 1:1 to 1.0 mg / mL. The concentrate was then sonicated in an ice bath for 10 min under nitrogen protection at 100 W. After centrifugation at 2000 rpm for 5 min to remove large agglomerates, the supernatant was collected. The composite nanosheet precipitate was collected by centrifugation at 9000 rpm for 10 min. The sample was washed twice with deionized ethanol and once with deionized water to obtain the final sample, which could be used for experimental testing. Ti3C2T x MXene sample: Take freshly exfoliated Ti3C2T x The MXene supernatant was diluted to 0.03 mg / mL with deionized water, sonicated at low power in an ice bath for 4 min, and 6 μL was added dropwise onto an ultrathin carbon membrane copper grid. After standing for 2 min, excess liquid was removed from the edge with filter paper, and the mixture was quickly rinsed once with 5 μL of anhydrous ethanol and vacuum dried at room temperature for 9 h.

[0041] PIL-MXene / Fe3O4 sample: The purified PIL-MXene / Fe3O4 dispersion was diluted to 0.05 mg / mL, and gently vortexed or sonicated in an ice bath for 3 min to allow Fe3O4 to spread evenly on the sheet surface. 6 μL was added to an ultrathin carbon film copper mesh, allowed to stand for 1 min, and then excess liquid was removed. The sample was then vacuum dried at room temperature and tested using a field emission transmission electron microscope (FET). The accelerating voltage was 200 kV, the TEM magnification was 20000×-100000×, and the HRTEM magnification was ≥500000×. The test results are as follows: Figure 2 As shown; Ti3C2T x MXene appears as translucent, wrinkled two-dimensional sheets with thinner edges and locally visible layered folds. This morphology indicates that after LiF / HCl etching and ultrasonic exfoliation, the Al layer of Ti3AlC2 was removed, forming a few-layer MXene. PIL-MXene / Fe3O4 appears as a two-dimensional sheet with a large number of dark nanoparticles distributed on the main body. The particle size is mainly 10-30 nm, close to the setting of about 20 nm for F3O4 nanoparticles in the raw material. The edges of the sheets should be more blurred than bare MXene, and a low-contrast coating layer can be seen locally, indicating the presence of an amorphous polyionic liquid shell on the sheet surface. If lattice fringes of about 0.253 nm appear in the HRTEM illustration, they can be attributed to the (311) crystal plane of Fe3O4, proving that Fe3O4 is not simply image contamination, but rather crystalline nanoparticles loaded in the MXene / PIL system.

[0042] Experimental Example 2 The purified PIL-MXene / Fe3O4 dispersion from Example 1 was diluted to 0.05 mg / mL, gently sonicated in an ice bath for 4 min, and 5 μL was added dropwise onto an ultrathin carbon film copper grid. The mixture was allowed to stand for 1 min and then vacuum dried for 6 h. A field emission STEM with an EDS detector was used, with an accelerating voltage of 200 kV, a convergence half-angle of 10-20 mrad, a probe current of 50-150 pA, and a cumulative time of 5-15 min. The test results are as follows: Figure 3 As shown; In the figure, Ti and C are continuously distributed throughout the entire sheet, proving that Ti3C2T x The MXene core is present. N, F, and S are uniformly distributed within the lamellar region, originating from imidazolium-type polyionic liquids and TFSI anions, proving that the polyionic liquid shell was successfully grafted or coated. Fe and O are distributed in a dotted or island-like pattern, basically corresponding to the bright spots in HAADF, proving that Fe3O4 particles are loaded on the lamellar surface or in the shell network.

[0043] Experimental Example 3 In Example 1, Ti3AlC2MAX powder and Ti3C2T powder were respectively taken. xMXene, PIL-MXene, and PIL-MXene / Fe3O4 were tested using an X-ray diffractometer with a CuKα X-ray source (λ = 1.5406 Å). The tube voltage / current was 40 kV / 40 mA, the scanning mode was θ-2θ, the standard scanning range was 3°-70°, the fine scanning range in the low-angle region was 3°-15°, the standard scanning rate was 1-2° / min, and the low-angle scanning rate was 0.2-0.5° / min. The test results are as follows: Figure 4 As shown; The Ti3AlC2MAX sample exhibits characteristic diffraction peaks of the MAX phase. After etching with LiF / HCl, the Ti3C2T... x The low-angle (002) peak of MXene should shift to a lower angle and become significantly wider, indicating that the Al layer is removed, the interlayer spacing increases, and the lamellar order decreases. This result is consistent with the mechanism described in the specification: "HF selective etching of Al atomic layers, lithium ion insertion to assist in widening the interlayer spacing, and ultrasonic exfoliation to form few-layer MXene." The (002) peak of PIL-MXene further widens or slightly shifts to a lower angle, indicating that the polyionic liquid enters the lamellar surface or interlayer region, making the interlayer structure more porous. In addition to retaining the low-angle peak of MXene, PIL-MXene / Fe3O4 also exhibits characteristic peaks of Fe3O4, typically located around 30.1°, 35.5°, 43.1°, 57.0°, and 62.6°, corresponding to the crystal plane diffraction of Fe3O4.

[0044] The XRD pattern confirms that the MAX phase has transformed into Ti3C2T. x MXene;Fe3O4 is introduced in the form of crystalline particles.

[0045] Experiment Example 4 The Ti3AlC2MAX powder and Ti3C2T from Example 1 were used. x MXene, PIL-MXene, and PIL-MXene / Fe3O4 were freeze-dried separately; KBr was dried at 120℃ for 4 hours and then cooled in a desiccator for later use; 2 mg of sample was mixed with 100 mg of dried KBr, compressed into tablets, and analyzed by ATR-FTIR, with a test range of 4000-4000 cm⁻¹. -1 4cm resolution -1 The number of scans was 64, and the test results were as follows: Figure 5 As shown; Ti3C2T x A broad -OH absorption band appears in MXene, typically located at 3200-3600 cm⁻¹. -1 This indicates the presence of -OH groups, adsorbed water, or end-group structures on the surface; Ti-O / Ti-F correlated vibrations are visible in the low wavenumber region. PIL-MXene, compared to Ti3C2T... xMXene adds or enhances the following characteristic peak: 3100cm -1 Nearby: imidazolium ring or organic segment CH stretching vibration; 1570–1640 cm⁻¹ -1 Nearby: Imidazolium ring C=N, C=C vibrations; 1350cm -1 Nearby: SO2 asymmetric stretching vibration in TFSI anions; 1180–1130 cm⁻¹ -1 Nearby: SO2 symmetric stretching and CF-related vibrations; 1050cm -1 Nearby: SNS or CF related vibrations.

[0046] PIL-MXene / Fe3O4 reinforced 570-590cm -1 The nearby Fe-O vibration peaks, while the Ti-O region still exists, indicate that the polyionic liquid is not simply physically mixed in, but interacts with the MXene surface end groups to form a shell; Fe3O4 is also introduced into the composite structure.

[0047] Experimental Example 5 The comprehensive performance of the lubricating greases prepared in Examples 1-7 and Comparative Examples 1-4 was determined. (1) Basic physicochemical properties and structural stability tests: Cone penetration test: Refer to standard GB / T 269-2023 "Determination of Cone Penetration of Lubricating Greases and Petroleum Greases" and use a grease cone penetration tester for testing. Test conditions: 25℃, 0.1mm unit. Record the cone penetration. Then, at 10... 5 After each shearing, the cone penetration was measured, and the rate of change was calculated as (cone penetration difference / initial cone penetration) × 100%. Dropping point test: Using a grease dropping point tester, the temperature was increased at a rate of 2℃ / min, and the temperature at which the first drop fell was recorded. Water loss test: A water loss test device was used. The test conditions were 79℃±2℃, 1h, and water flow rate of 5mL / s. The percentage of mass lost was calculated. The test results are shown in Table 2. Table 2 Comparison of basic physicochemical properties and structural stability of Examples 1-7 and Comparative Examples 1-4

[0048] (2) Extreme pressure anti-wear performance and micro-pitting corrosion protection response test: Extreme pressure performance test: Referring to standard GB / T 3142-2019 "Determination of load-carrying capacity of lubricants by four-ball method", a four-ball extreme pressure testing machine was used with a speed of 1450±50 r / min. The load was gradually increased until the steel balls were stuck, and the maximum non-sticking load, i.e., PB value, was recorded. The load was gradually increased until sintering, and the sintering load PD value was recorded. Wear resistance test: A four-ball wear tester was used. The test conditions were 392 N, 60 min, and 1200 r / min. The average wear scar diameter of the steel balls was measured. Micropitting test: A10 FZG gears were used. The test oil temperature was controlled at 80℃±2℃, the gear speed was 2000rpm, and the applied torque was 90% of the gearbox's rated torque. The test was conducted continuously for 100 hours. After the test, the gear tooth surface was cleaned with petroleum ether and photographed under a stereomicroscope (20×). The percentage of the damaged area to the total tooth surface area was calculated. The test results are shown in Table 3. Table 3 Comparison of extreme pressure anti-wear performance and micropitting protection response performance of Examples 1-7 and Comparative Examples 1-4

[0049] In summary, Comparative Example 1, lacking the phosphorus-sulfur-molybdenum extreme pressure anti-wear agent, resulted in a lack of effective cascade protection across the entire temperature range, leading to severe initial wear and a sharp decline in extreme pressure anti-wear capability. Furthermore, the polar groups in this additive molecule, which normally assist the thickener in stabilizing the base oil, were absent, making the soap fiber network more susceptible to shear damage, resulting in decreased change rate and water resistance. Comparative Example 2, lacking the addition of a complex calcium sulfonate base grease, which is a core material for constructing the three-dimensional fiber network framework, was rendered ineffective without a thickener. The base oil and all additives were merely a simple physical mixture, unable to achieve thixotropy and mechanical stability. Under high shear and water spray conditions, the mixture rapidly flows away, and the gear surface cannot maintain an effective oil film, leading to direct metal-to-metal contact, severe wear, and even sintering. Comparative Example 3, without the addition of core-shell nanosheets, shows that the grease loses its responsiveness and self-healing function. When alternating load impact causes the oil film to rupture instantaneously, the tribochemical reaction of traditional additives requires seconds to form a film, during which time a large number of micro-protrusion contacts and micro-pitting corrosion have already occurred. The lack of rolling repair effect of Fe3O4 means that the existing minor wear cannot be repaired, and wear continues to accumulate. Although the extreme pressure performance decreases somewhat, it is not the most severe, indicating that the phosphorus-sulfur-molybdenum-containing extreme pressure anti-wear... The agent can still provide some extreme pressure anti-wear effect, but the protection against micropitting mainly relies on the rapid response mechanism of core-shell nanosheets. Comparative Example 4 uses unmodified hexagonal boron nitride nanosheets. The surface of unmodified hexagonal boron nitride nanosheets is inert and has poor oleophilicity. In the grease, they are prone to agglomerate into micron-sized aggregates, which cannot be uniformly dispersed. Agglomerated hexagonal boron nitride not only cannot effectively enhance the soap fiber network, but also destroys the structural integrity, making the thickener more susceptible to shearing, increasing the precipitation of base oil, and reducing the water-resistant ability. As hard particles, the aggregates may aggravate wear, increase the diameter of the wear scar, and cause protective blank areas due to uneven local concentration, thus increasing the area of ​​micropitting damage.

Claims

1. A special lubricating grease for wind turbine gearboxes, characterized in that, Based on 100 parts by weight of the finished grease, the grease comprises: 20-30 parts of high-alkalinity synthetic calcium sulfonate, 1.5-3.0 parts of 12-hydroxystearic acid, 0.5-1.8 parts of boric acid, 0.8-2.2 parts of calcium hydroxide, 2.0-4.0 parts of phosphorus-sulfur-molybdenum extreme pressure anti-wear agent, 0.3-1.2 parts of PIL-MXene concentrate, 0.2-0.8 parts of surface-modified hexagonal boron nitride nanosheets, 2.0-4.5 parts of polyisobutylene adhesive, 0.6-1.5 parts of antioxidant and rust-preventive composition, and the balance being synthetic base oil; The high-alkalinity synthetic calcium sulfonate is converted to form a composite calcium sulfonate thickening network containing calcite-type calcium carbonate; the PIL-MXene concentrated slurry is a polyionic liquid modified Ti3C2T. x MXene composite nanosheets with few-layer Ti3C2T x The core is MXene, with a polyionic liquid shell covalently grafted onto the surface and loaded with Fe3O4 nanoparticles.

2. The special lubricating grease for wind turbine gearboxes according to claim 1, characterized in that, The synthetic base oil is prepared by uniformly mixing PAO8 and alkylnaphthalene AN30 at a mass ratio of 4:

1.

3. The special lubricating grease for wind turbine gearboxes according to claim 1, characterized in that, The total alkali value of the high-alkali-value alkylbenzene sulfonate calcium is 300-450 mg KOH / g.

4. The special lubricating grease for wind turbine gearboxes according to claim 1, characterized in that, The adhesive polymer is polyisobutylene (PIB) with a number-average molecular weight of 5,000-20,000; the antioxidant and rust-preventive composition consists of antioxidant 4,4'-dioctyldiphenylamine, rust inhibitor calcium petroleum sulfonate, and metal deactivator benzotriazole derivative T551.

5. A method for preparing a special lubricating grease for wind turbine gearboxes according to any one of claims 1-4, characterized in that, The specific preparation steps are as follows: S1: PAO8 and alkylnaphthalene AN30 are mixed evenly at a mass ratio of 4:1 to obtain base oil. The base oil and high-alkalinity synthetic calcium sulfonate are added to the reactor and stirred evenly at 60℃~80℃. Deionized water and glacial acetic acid are added for conversion, and the residual acid value is ≤0.5mgKOH / g. The characteristic peak of calcite-type CaCO3 is confirmed by XRD. 12-hydroxystearic acid, boric acid and calcium hydroxide are added, and the mixture is saponified and dehydrated to obtain the complex calcium sulfonate base ester. S2: Ti3AlC2MAX phase ceramic powder and LiF were added to HCl solution and etched by stirring; 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt, azobisisobutyronitrile initiator, and N,N'-methylenebisacrylamide were added, and PIL-MXene was obtained by polymerization under nitrogen; Fe3O4 was modified with silane, Fe3O4 nanoparticles were mixed in anhydrous ethanol, ultrasonically dispersed, modified with KH570, and then washed and dried to constant weight; then compounded with PIL-MXene to prepare PIL-MXene concentrated slurry; S3: Polyisobutylene succinic anhydride, toluene, C12 long-chain alkyl phosphate, and p-toluenesulfonic acid are added to a container for esterification. After vacuum distillation, phosphorus pentasulfide and sulfur powder are added to the residue for sulfidation. Molybdenum dialkyldithiocarbamate is added and the mixture is reacted under nitrogen protection at 80℃~100℃ for 2~4h. After the reaction is completed, the insoluble matter is removed by filtration, and the filtrate is concentrated and then vacuum devolatilized to obtain a phosphorus-sulfur-molybdenum extreme pressure anti-wear agent. S4: Take hexagonal boron nitride nanosheets, disperse them in anhydrous ethanol, add γ-aminopropyltriethoxysilane, control the pH at 4.5-5.5, ultrasonically disperse for 30 minutes, react at 60℃-80℃ for 4-6 hours; centrifuge and wash, vacuum dry at 60℃ for 12 hours to obtain modified hexagonal boron nitride nanosheets; cool the base grease to 80℃-90℃, add phosphorus-sulfur-molybdenum extreme pressure anti-wear agent; cool to 60℃-80℃, add PIL-MXene concentrated slurry, modified h-BN, adhesive polymer polyisobutylene PIB, 4,4'-dioctyl diphenylamine antioxidant, rust inhibitor calcium petroleum sulfonate, and metal deactivator benzotriazole derivative T551; disperse at 4000 rpm for 20 minutes, grind and defoam; adjust the amount of base oil added so that the total mass of the obtained grease is 100 parts.

6. The method for preparing a special lubricating grease for wind turbine gearboxes according to claim 5, characterized in that, The conversion described in step S1 specifically involves introducing CO2 to convert calcium carbonate crystals; controlling the conversion temperature at 70℃~90℃ and the conversion time at 60~120min.

7. The method for preparing a special lubricating grease for wind turbine gearboxes according to claim 5, characterized in that, The saponification and dehydration refining process described in step S1 specifically involves saponification at 95℃~110℃ for 60~120 minutes; heating to 150℃~180℃ for dehydration refining; and cooling to below 90℃.

8. The method for preparing a special lubricating grease for wind turbine gearboxes according to claim 5, characterized in that, The stirring etching described in step S2 specifically involves stirring and etching in a 35°C water bath for 24 hours; centrifuging and washing at 3500 rpm for 5 minutes until the pH of the supernatant is 6; collecting the precipitate and dispersing it in deionized water; ultrasonically peeling with nitrogen gas at 300W for 1 hour; and centrifuging at 3500 rpm for 1 hour to collect the supernatant.

9. The method for preparing a special lubricating grease for wind turbine gearboxes according to claim 5, characterized in that, The vulcanization reaction described in step S3 specifically involves heating to 120℃~130℃ and stirring the vulcanization reaction for 3~4 hours.

10. The method for preparing a special lubricating grease for wind turbine gearboxes according to claim 5, characterized in that, The grinding and degassing described in step S4 specifically involves grinding three times using a three-roll mill, with a gap of 50 μm for the first time, 30 μm for the second time, 15 μm for the third time, and finally degassing under vacuum at -0.095 MPa for 30 minutes.

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