Anti-pitting automobile transmission lubricating oil and preparation method thereof

Abstract

The invention relates to the technical field of lubricating oil, in particular to pitting-corrosion-resistant automobile transmission lubricating oil and a preparation method thereof. The method comprises the following steps: (1) mixing and filtering spiral carbon nanotubes, 2, 5-bis (octyl dithio) thiadiazole and pentaerythritol tetraborate triethanolamine ester, and mixing a filtered substance, an antioxidant and phosphorus-doped NiMn-coated CuO / CF treated by a first coupling agent to obtain a composite extreme pressure agent; (2) mixing a composite extreme pressure agent, a purification dispersant, a defoaming agent, a viscosity index improver and the nano-copper treated by the second coupling agent to obtain a composite additive; and (3) uniformly mixing the composite additive, the hydroxylated poly-alpha-olefin and methylcyclopentane according to the mass ratio of (0.1-0.3): 1: (2-3) to obtain the pitting-corrosion-resistant automobile transmission lubricating oil. The composite extreme pressure agent can sequentially form a plurality of extreme pressure agents to form a multi-layer film, so that the wear resistance of the lubricating oil is improved. The lubricating oil provided by the invention has excellent wear resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating oils, in particular to a pitting-resistant automobile transmission lubricating oil and a preparation method thereof. Background Art

[0002] Automotive gearboxes utilize gear transmissions. When the gears mesh, the tooth surfaces are repeatedly subjected to Hertzian contact stresses. This long-term effect leads to fatigue of the surface material, eventually causing small pieces of metal to break off from the tooth surfaces, forming pits and causing contact fatigue spalling. The presence of pits on the tooth surfaces, also known as pitting or micropitting, is a primary characteristic of contact fatigue damage in gears. Furthermore, when lubricating oil viscosity is too low, the oil supply is insufficient, or under extreme loads, the oil film breaks down, failing to isolate metal contact, leading to dry friction and pitting on the gear surfaces. In the field of lubricating oil technology, contact fatigue prevention primarily focuses on preventing the early formation of pits, or pitting or micropitting, with particular attention being paid to the filling and anti-wear effects of nanoparticles. For example, CN 117701324A discloses an anti-pitting vehicle gear oil and its preparation method. Nano-solid materials act as a support on the gear surface, increasing the lubricating oil film thickness and reducing gear contact stress. The nano-solid materials act as friction agents, reducing the likelihood of cracks forming on the gear surface and preventing crack propagation. Nano-metal particles are also used for crack repair, reducing the probability of micropitting and pitting. Another example is CN 118652722A, which discloses a micropitting-resistant wind turbine gear oil and its preparation method. Nanoparticles can react with thiophosphates to rapidly form a tribofilm exceeding 2 μm thick in situ under frictional induction. The nanoparticles are evenly distributed within the tribofilm, effectively improving its mechanical properties. The rapid formation of this ultra-thick tribofilm can effectively reduce plastic deformation in the surface and subsurface layers of metal materials. The synergistic effect of the nanoparticles and thiophosphates produces friction-reducing and anti-wear properties, which can also reduce the accumulated shear stress in the surface and subsurface layers. Existing technologies focus more on the filling effect of lubricating oil nanoparticles on gear surface cracks and increasing oil film thickness, but fail to address the issues of improving oil film toughness and strength during high-speed operation and preventing the polishing effect of extreme pressure agents on gears at low speeds. Summary of the Invention

[0003] The purpose of the present invention is to provide an anti-pitting corrosion automobile transmission lubricating oil and a preparation method thereof, wherein the obtained lubricating oil has excellent anti-wear performance.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] A method for preparing a pitting-resistant automobile transmission lubricant comprises the following steps:

[0006] (1) mixing helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole and pentaerythritol triethanolamine borate and filtering, and mixing the filtrate, an antioxidant and phosphorus-doped NiMn@CuO / CF treated with a first coupling agent to obtain a composite extreme pressure agent;

[0007] (2) mixing a composite extreme pressure agent, a detergent dispersant, a defoaming agent, a viscosity index improver, and nano-copper treated with a second coupling agent to obtain a composite additive;

[0008] (3) The composite additive, hydroxylated polyalphaolefin and methylcyclopentane are uniformly mixed in a mass ratio of (0.1-0.3):1:(2-3) to obtain the anti-pitting corrosion automobile transmission lubricant.

[0009] Furthermore, the phosphorus-doped NiMn@CuO / CF is in the shape of a nanosphere with a particle size of 2 to 5 nm; the length of the helical carbon nanotube is 15 to 35 nm and the diameter is 10 to 20 nm.

[0010] Furthermore, in the composite extreme pressure agent, the mass ratio of the helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine ester and phosphorus-doped NiMn@CuO / CF is 6:(2-3):(0.6-1.2):(1-2).

[0011] Furthermore, in step (1):

[0012] First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester are mixed evenly and heated to 120-140°C;

[0013] Then, the acidified helical carbon nanotubes are added and mixed, and vacuum treatment is performed for 30 to 50 minutes;

[0014] Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering;

[0015] The filtrate and the antioxidant are evenly mixed, and then the phosphorus-doped NiMn@CuO / CF treated with the first coupling agent is added to obtain a composite extreme pressure agent.

[0016] Furthermore, in step (1), the synthesis step of pentaerythritol tetraborate triethanolamine ester includes:

[0017] Pentaerythritol is dissolved in toluene, boric acid and tetrabutyl titanate are added, and the mixture is heated to reflux temperature under an inert atmosphere and reacted for 4 to 6 hours. After the reaction is completed, the solvent is removed by distillation under reduced pressure to obtain a pentaerythritol tetraborate intermediate.

[0018] The pentaerythritol tetraborate intermediate is dissolved in ethanol, triethanolamine is added, and then the temperature is raised to 60-80° C. and reacted for 2-3 hours. After the reaction is completed, the ethanol is removed by reduced pressure distillation to obtain pentaerythritol tetraborate triethanolamine ester.

[0019] Furthermore, in the step (2), the mass ratio of the composite extreme pressure agent, the detergent dispersant, the defoaming agent, the viscosity index improver and the nano-copper treated with the second coupling agent is (1-4):(4-6):(4-6):(0.5-1):(0.5-1).

[0020] Furthermore, the first coupling agent is selected from one of titanate, silane coupling agent, and phosphate ester, and the second coupling agent is selected from one of titanate, silane coupling agent, and phosphate ester, and the first coupling agent and the second coupling agent are selected from different components.

[0021] Furthermore, the antioxidant is a mixture of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2.

[0022] Furthermore, the detergent dispersant is selected from two of polyisobutylene succinimide, polyisobutylene succinate and alkyl salicylate;

[0023] The viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0024] A pitting-resistant automobile transmission lubricant is prepared by adopting the above method.

[0025] The technical solution provided by the present invention can have the following beneficial effects:

[0026] Two extreme pressure agents, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester, were filled into the lumen of a helical carbon nanotube. Simultaneously, phosphorus-doped NiMn@CuO / CF treated with a first coupling agent was attached to the surface of the helical carbon nanotube to create a composite extreme pressure agent. This composite extreme pressure agent can form a multilayer film with multiple extreme pressure agents in sequence, improving wear resistance.

[0027] Under high temperature conditions, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine ester and phosphorus-doped NiMn@CuO / CF undergo a chemical reaction, making the resulting multilayer film an elastic film. The nano-copper or nano-copper oxide particles generated by the phosphorus-doped NiMn@CuO / CF can fill the film layer, making the film layer stronger. When the oil temperature drops, that is, when the gear runs at low speed, the film layer is not easy to peel off, preventing the "polishing effect". DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0029] A method for preparing a pitting-resistant automotive transmission lubricant according to an embodiment of the present invention is characterized by comprising the following steps:

[0030] (1) mixing helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester and filtering, and mixing the filtrate, an antioxidant and phosphorus-doped NiMn@CuO / CF treated with a first coupling agent to obtain a composite extreme pressure agent;

[0031] (2) mixing a composite extreme pressure agent, a detergent dispersant, a defoaming agent, a viscosity index improver, and nano-copper treated with a second coupling agent to obtain a composite additive;

[0032] (3) The composite additive, hydroxylated polyalphaolefin and methylcyclopentane are uniformly mixed in a mass ratio of (0.1-0.3):1:(2-3) to obtain the anti-pitting corrosion automobile transmission lubricant.

[0033] In this scheme, two extreme pressure agents, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine, are packed into the lumen of a helical carbon nanotube. Simultaneously, phosphorus-doped NiMn@CuO / CF, treated with a first coupling agent, is attached to the surface of the helical carbon nanotubes to create a composite extreme pressure agent. When the gearbox operates at high speeds, the composite extreme pressure agent first releases the phosphorus-doped NiMn@CuO / CF, which adsorbs onto the gear surface to form a film. As the lubricating oil temperature continues to rise and the helical carbon nanotubes release 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine, the two extreme pressure agents combine with the initial film to form a multilayer film, enhancing wear resistance. Of particular note is that under high temperature conditions, the chemical reaction between 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine ester, and phosphorus-doped NiMn@CuO / CF makes the resulting multilayer film elastic. Furthermore, the nano-copper or nano-copper oxide particles generated by the phosphorus-doped NiMn@CuO / CF fill the film, making it more durable. This prevents the film from peeling off when the oil temperature drops, i.e., when the gears operate at low speeds, thus preventing the "polishing effect." Furthermore, the use of helical carbon nanotubes in this solution, with their smaller contact area, further reduces friction between gears and facilitates the separate release of the three extreme pressure agents.

[0034] This solution specifies a mass ratio of composite additives, hydroxylated polyalphaolefins, and methylcyclopentane of (0.1-0.3):1:(2-3). Using hydroxylated polyalphaolefins and methylcyclopentane as the base oil, this reduces the amount of fully synthetic polyalphaolefins used, thereby lowering the cost of hybrid vehicle engine lubricants. The composite extreme pressure agent and nano-copper provide synergistic anti-wear properties, ensuring the lubricant meets low-temperature start-up wear resistance requirements. Furthermore, the addition of antioxidants, detergent dispersants, defoamers, and viscosity index improvers enhances the lubricant's stability and cleanliness.

[0035] Specifically, 2,5-bis(octyldithio)thiadiazole (TH561) is a yellowish-brown transparent liquid produced by introducing heteroatoms with anti-wear activity, such as S and N, into the main chain of the macromolecule through a complex oxidative coupling reaction using mercaptothiadiazole and long-chain alkanethiols as raw materials. TH561 exhibits excellent extreme pressure, anti-wear, antioxidant, and corrosion resistance, as well as the ability to reduce metal activity. As an extreme pressure anti-wear agent, TH561 can significantly inhibit the corrosive effects of sulfides generated during lubricant use and is also an excellent antioxidant. Pentaerythritol tetraborate triethanolamine ester has a structure of B4(OR)4(OR')4 (R = TEA group, R' = pentaerythritol group), resulting in a high-density film. Phosphorus-doped NiMn@CuO / CF can reduce the friction coefficient and enhance oil film strength.

[0036] Preferably, the phosphorus-doped NiMn@CuO / CF is in the shape of a nanosphere with a particle size of 2 to 5 nm; the length of the helical carbon nanotube is 15 to 35 nm and the diameter is 10 to 20 nm.

[0037] During the preparation process, phosphorus-doped NiMn@CuO / CF nanoparticles are obtained by controlling reaction conditions such as reaction temperature, time, and precursor concentration. Alternatively, phosphorus-doped NiMn@CuO / CF nanoparticles can be prepared using different synthesis methods, such as sol-gel and spray drying. Smaller-sized phosphorus-doped NiMn@CuO / CF can fill the interstices of the helical carbon nanotubes and seal the end openings. By limiting the length of the helical carbon nanotubes to 15-35 nm and the diameter to 10-20 nm, they have a smaller aspect ratio, making them easier to fill not only the extreme pressure agent but also the tiny cracks on the gear surface.

[0038] Furthermore, in the composite extreme pressure agent, the mass ratio of the helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine ester and phosphorus-doped NiMn@CuO / CF is 6:(2-3):(0.6-1.2):(1-2).

[0039] By limiting the mass ratio of the three extreme pressure agents and balancing the proportions of the three elements sulfur, phosphorus and boron, the anti-pitting effect of the lubricating oil is ensured and the film stability under oil temperature fluctuations is improved.

[0040] The steps for preparing the composite extreme pressure agent in one embodiment of the present invention are as follows:

[0041] First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester are mixed evenly and heated to 120-140°C to make the mixture have good fluidity and more easily penetrate into the helical carbon nanotubes;

[0042] Then, the acidified helical carbon nanotubes are added and mixed, and vacuum treatment is performed for 30 to 50 minutes to allow 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester to be fully filled into the helical carbon nanotubes;

[0043] Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering;

[0044] The filtrate and the antioxidant are evenly mixed, and then the phosphorus-doped NiMn@CuO / CF treated with the first coupling agent is added to obtain a composite extreme pressure agent.

[0045] Understandably, the phosphorus-doped NiMn@CuO / CF treated with a coupling agent more readily adheres to the helical carbon nanotubes. Furthermore, the pre-introduction of the antioxidant ensures chemical stability during the mixing process. In the filtrate, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine not only fill the helical carbon nanotubes and adhere to their outer surfaces, but also, during the subsequent mixing step, the liquid extreme pressure agent on the outer surfaces of the helical carbon nanotubes is dispersed throughout the system.

[0046] The synthesis steps of pentaerythritol tetraborate triethanolamine ester in one embodiment of the present invention include:

[0047] Pentaerythritol is dissolved in toluene, boric acid and tetrabutyl titanate are added, and the mixture is heated to reflux temperature under an inert atmosphere and reacted for 4 to 6 hours. After the reaction is completed, the solvent is removed by distillation under reduced pressure to obtain a pentaerythritol tetraborate intermediate. The pentaerythritol tetraborate intermediate is dissolved in ethanol, triethanolamine is added, and then the temperature is increased to 60-80°C and reacted for 2 to 3 hours. After the reaction is completed, the ethanol is removed by distillation under reduced pressure to obtain pentaerythritol tetraborate triethanolamine ester.

[0048] Preferably, in step (2), the mass ratio of the composite extreme pressure agent, the detergent dispersant, the defoamer, the viscosity index improver, and the nano-copper treated with the second coupling agent is (1-4):(4-6):(4-6):(0.5-1):(0.5-1). The detergent dispersant helps keep the engine clean, the defoamer can reduce the formation of foam, and the viscosity index improver can improve the viscosity characteristics of the lubricating oil. By limiting the mass ratio range of the detergent dispersant, the defoamer, the viscosity index improver, and the second additive, it is possible to ensure that each component exerts its optimal effect while ensuring the stability and reliability of the lubricating oil under different operating conditions.

[0049] Preferably, the first coupling agent is selected from a titanate, a silane coupling agent, and a phosphate ester, and the second coupling agent is selected from a titanate, a silane coupling agent, and a phosphate ester, and the first coupling agent and the second coupling agent are selected from different components. The two different coupling agents can respectively improve the lubrication performance and enhance the wear resistance of the lubricant. For example, a titanate coupling agent can provide excellent heat resistance and oxidation resistance, while a silane coupling agent can improve the adhesion and hydrolysis resistance of the lubricant. In this way, the combination of coupling agents can be flexibly selected according to actual needs to achieve the purpose of optimizing the performance of the lubricant. Under complex operating conditions of the gearbox, the problem of low-temperature startup wear can be effectively reduced, and the overall performance and service life of the lubricant can be improved.

[0050] Preferably, the antioxidant is a compound of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2. The compounding exerts a synergistic effect of the two, and the compounded antioxidant can significantly improve the antioxidant performance of the lubricating oil and extend the service life of the lubricating oil.

[0051] Preferably, the detergent dispersant is selected from two of polyisobutylene succinimide, polyisobutylene succinate and alkyl salicylate;

[0052] The viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0053] Polyisobutylene succinimide prevents sludge and carbon deposits, keeping the engine clean; polyisobutylene succinate provides dispersant and rust prevention properties, preventing deposit formation and protecting metal surfaces; alkyl salicylates neutralize acidic substances, reduce oxidation products, and prevent deposits. Using these two combined as detergent dispersants significantly extends the service life of lubricants.

[0054] Due to its fluorinated groups, poly(perfluorohexyl methacrylate) exhibits excellent high-temperature resistance (>200°C), oxidation resistance, and chemical inertness. The combination of poly(perfluorohexyl methacrylate) and poly(methacrylate) acts as a viscosity index improver, enhancing the compatibility of two base oils and improving the low-temperature fluidity of the lubricant.

[0055] Correspondingly, the present invention also provides a pitting-resistant automobile transmission lubricant, which is prepared by the above method.

[0056] The present invention is further illustrated below with reference to specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit its scope. Experimental methods in the following examples, where specific conditions are not specified, were generally selected according to conventional methods and conditions or according to commercial product specifications. The reagents described, unless otherwise specified, were commercially available; and the performance of products from different sources did not significantly affect each other.

[0057] Example 1

[0058] The steps of the preparation method of the anti-pitting automobile transmission lubricating oil of this embodiment are as follows:

[0059] (1) First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester were mixed uniformly and heated to 120°C;

[0060] Then, acid-treated helical carbon nanotubes (length of about 15 to 35 nm, diameter of about 10 to 20 nm) were added, mixed, and vacuum-treated for 50 min;

[0061] Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering;

[0062] The filtrate and antioxidant were then mixed evenly, followed by the addition of phosphorus-doped NiMn@CuO / CF (particle size approximately 2-5 nm) treated with the first coupling agent to produce a composite extreme pressure agent. The mass ratio of helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine, and phosphorus-doped NiMn@CuO / CF was 6:3:1.2:2. The antioxidant was a mixture of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2.

[0063] (2) A composite extreme pressure agent, a detergent dispersant, a defoamer, a viscosity index improver, and nano-copper treated with a second coupling agent are mixed in a mass ratio of 1:4:6:0.5:0.5 to obtain a composite additive. The first coupling agent is a titanate, and the second coupling agent is a silane coupling agent. The detergent dispersant is composed of polyisobutylene succinimide and polyisobutylene succinate; and the viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0064] (3) The composite additive, hydroxylated poly-α-olefin and methylcyclopentane are uniformly mixed in a mass ratio of 0.3:1:2 to obtain the anti-pitting corrosion automobile transmission lubricant.

[0065] Example 2

[0066] The steps of the preparation method of the anti-pitting automobile transmission lubricating oil of this embodiment are as follows:

[0067] (1) First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester were mixed uniformly and heated to 130°C;

[0068] Then, acid-treated helical carbon nanotubes (length of about 15 to 35 nm, diameter of about 10 to 20 nm) were added, mixed, and vacuum-treated for 40 minutes;

[0069] Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering;

[0070] The filtrate and antioxidant were then mixed evenly, followed by the addition of phosphorus-doped NiMn@CuO / CF (particle size approximately 2-5 nm) treated with the first coupling agent to produce a composite extreme pressure agent. The mass ratio of helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine, and phosphorus-doped NiMn@CuO / CF was 6:2:0.6:1. The antioxidant was a mixture of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2.

[0071] (2) A composite extreme pressure agent, a detergent dispersant, a defoamer, a viscosity index improver, and nano-copper treated with a second coupling agent are mixed in a mass ratio of 1:6:4:1:0.5 to obtain a composite additive. The first coupling agent is a phosphate ester, and the second coupling agent is a titanate. The detergent dispersant is composed of polyisobutylene succinate and alkyl salicylate; and the viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0072] (3) The composite additive, hydroxylated poly-α-olefin and methylcyclopentane are uniformly mixed in a mass ratio of 0.1:1:3 to obtain the anti-pitting corrosion automobile transmission lubricant.

[0073] Example 3

[0074] The steps of the preparation method of the anti-pitting automobile transmission lubricating oil of this embodiment are as follows:

[0075] (1) First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester were mixed uniformly and heated to 120°C;

[0076] Then, acid-treated helical carbon nanotubes (length of about 15 to 35 nm, diameter of about 10 to 20 nm) were added, mixed, and vacuum-treated for 50 min;

[0077] Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering;

[0078] The filtrate and antioxidant were then mixed evenly, followed by the addition of phosphorus-doped NiMn@CuO / CF (particle size approximately 2-5 nm) treated with the first coupling agent to produce a composite extreme pressure agent. The mass ratio of helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine, and phosphorus-doped NiMn@CuO / CF was 6:3:0.6:1. The antioxidant was a mixture of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2.

[0079] (2) A composite extreme pressure agent, a detergent dispersant, a defoaming agent, a viscosity index improver, and nano-copper treated with a second coupling agent are mixed in a mass ratio of 4:4:6:0.5:0.5 to obtain a composite additive. The first coupling agent is a silane coupling agent, and the second coupling agent is a titanate. The detergent dispersant is composed of polyisobutylene succinimide and alkyl salicylate; and the viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0080] (3) The composite additive, hydroxylated poly-α-olefin and methylcyclopentane are uniformly mixed in a mass ratio of 0.3:1:3 to obtain the anti-pitting corrosion automobile transmission lubricant.

[0081] Example 4

[0082] The steps of the preparation method of the anti-pitting automobile transmission lubricating oil of this embodiment are as follows:

[0083] (1) First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester are mixed uniformly and heated to 140°C;

[0084] Then, acid-treated helical carbon nanotubes (length of about 15 to 35 nm, diameter of about 10 to 20 nm) were added, mixed, and vacuum-treated for 30 min;

[0085] Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering;

[0086] The filtrate and antioxidant were then mixed evenly, followed by the addition of phosphorus-doped NiMn@CuO / CF (particle size approximately 2-5 nm) treated with the first coupling agent to produce a composite extreme pressure agent. The mass ratio of helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine, and phosphorus-doped NiMn@CuO / CF was 6:2:0.6:1. The antioxidant was a mixture of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2.

[0087] (2) A composite extreme pressure agent, a detergent dispersant, a defoaming agent, a viscosity index improver, and nano-copper treated with a second coupling agent are mixed in a mass ratio of 1:4:6:0.5:0.5 to obtain a composite additive. The first coupling agent is a titanate, and the second coupling agent is a silane coupling agent. The detergent dispersant is composed of polyisobutylene succinimide and alkyl salicylate; and the viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0088] (3) The composite additive, hydroxylated poly-α-olefin and methylcyclopentane are uniformly mixed in a mass ratio of 0.1:1:3 to obtain the anti-pitting corrosion automobile transmission lubricant.

[0089] Example 5

[0090] The steps of the preparation method of the anti-pitting automobile transmission lubricating oil of this embodiment are as follows:

[0091] (1) First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester were mixed uniformly and heated to 130°C;

[0092] Then, acid-treated helical carbon nanotubes (length of about 15 to 35 nm, diameter of about 10 to 20 nm) were added, mixed, and vacuum-treated for 40 minutes;

[0093] Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering;

[0094] The filtrate and antioxidant were then mixed evenly, followed by the addition of phosphorus-doped NiMn@CuO / CF (particle size approximately 2-5 nm) treated with the first coupling agent to produce a composite extreme pressure agent. The mass ratio of helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine, and phosphorus-doped NiMn@CuO / CF was 6:3:0.6:1. The antioxidant was a mixture of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2.

[0095] (2) A composite extreme pressure agent, a detergent dispersant, a defoaming agent, a viscosity index improver, and nano-copper treated with a second coupling agent are mixed in a mass ratio of 1:6:4:1:0.5 to obtain a composite additive. The first coupling agent is a silane coupling agent, and the second coupling agent is a titanate. The detergent dispersant is selected from polyisobutylene succinimide and polyisobutylene succinate; and the viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0096] (3) The composite additive, hydroxylated poly-α-olefin and methylcyclopentane are uniformly mixed in a mass ratio of 0.3:1:3 to obtain the anti-pitting corrosion automobile transmission lubricant.

[0097] Example 6

[0098] The steps of the preparation method of the anti-pitting automobile transmission lubricating oil of this embodiment are as follows:

[0099] (1) First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester were mixed uniformly and heated to 130°C;

[0100] Then, acid-treated helical carbon nanotubes (length of about 15 to 35 nm, diameter of about 10 to 20 nm) were added, mixed, and vacuum-treated for 40 minutes;

[0101] Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering;

[0102] The filtrate and antioxidant were then mixed evenly, followed by the addition of phosphorus-doped NiMn@CuO / CF (particle size approximately 2-5 nm) treated with the first coupling agent to produce a composite extreme pressure agent. The mass ratio of helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine, and phosphorus-doped NiMn@CuO / CF was 6:3:1.2:2. The antioxidant was a mixture of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2.

[0103] (2) Mixing a composite extreme pressure agent, a detergent dispersant, a defoamer, a viscosity index improver, and nano-copper treated with a second coupling agent in a mass ratio of 4:4:6:0.5:0.5 to obtain a composite additive. The first coupling agent is a phosphate ester, the second coupling agent is a titanate ester, and the detergent dispersant is selected from polyisobutylene succinimide and alkyl salicylate;

[0104] The viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0105] (3) The composite additive, hydroxylated poly-α-olefin and methylcyclopentane are uniformly mixed in a mass ratio of 0.3:1:2 to obtain the anti-pitting corrosion automobile transmission lubricant.

[0106] Comparative Example 1

[0107] The steps of the preparation method of the lubricating oil of this comparative example are as follows:

[0108] (1) First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester, helical carbon nanotubes (length of about 15-35 nm, diameter of about 10-20 nm), antioxidant, and phosphorus-doped NiMn@CuO / CF treated with a first coupling agent (particle size of about 2-5 nm) were mixed evenly and then added to obtain a composite extreme pressure agent. Among them, the mass ratio of helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine ester, and phosphorus-doped NiMn@CuO / CF was 6:2:0.6:1. The antioxidant was dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2.

[0109] (2) A composite extreme pressure agent, a detergent dispersant, a defoamer, a viscosity index improver, and nano-copper treated with a second coupling agent are mixed in a mass ratio of 1:6:4:1:0.5 to obtain a composite additive. The first coupling agent is a phosphate ester, and the second coupling agent is a titanate. The detergent dispersant is composed of polyisobutylene succinate and alkyl salicylate; and the viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0110] (3) The composite additive, hydroxylated poly-α-olefin and methylcyclopentane are uniformly mixed in a mass ratio of 0.1:1:3 to obtain the anti-pitting corrosion automobile transmission lubricant.

[0111] Comparative Example 2

[0112] The steps of the preparation method of the lubricating oil of this comparative example are as follows:

[0113] (1) First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester were mixed uniformly and heated to 130°C;

[0114] Then, acid-treated helical carbon nanotubes (length of about 15 to 35 nm, diameter of about 10 to 20 nm) were added, mixed, and vacuum-treated for 40 minutes;

[0115] Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering;

[0116] The filtrate and antioxidant were then mixed evenly to obtain a composite extreme pressure agent. The composite extreme pressure agent comprised helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, and pentaerythritol tetraborate triethanolamine in a mass ratio of 6:2:0.6. The antioxidant was a mixture of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2.

[0117] (2) A composite extreme pressure agent, a detergent dispersant, a defoamer, a viscosity index improver, and nano-copper treated with a second coupling agent are mixed in a mass ratio of 1:6:4:1:0.5 to obtain a composite additive. The first coupling agent is a phosphate ester, and the second coupling agent is a titanate. The detergent dispersant is composed of polyisobutylene succinate and alkyl salicylate; and the viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0118] (3) The composite additive, hydroxylated poly-α-olefin and methylcyclopentane are uniformly mixed in a mass ratio of 0.1:1:3 to obtain the anti-pitting corrosion automobile transmission lubricant.

[0119] Comparative Example 3

[0120] The steps of the preparation method of the anti-pitting automobile transmission lubricating oil of this embodiment are as follows:

[0121] (1) First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester were mixed uniformly and heated to 130°C;

[0122] Then, acid-treated helical carbon nanotubes (length of about 15 to 35 nm, diameter of about 10 to 20 nm) were added, mixed, and vacuum-treated for 40 minutes;

[0123] Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering;

[0124] The filtrate and antioxidant were then mixed evenly, followed by the addition of phosphorus-doped NiMn@CuO / CF (particle size approximately 2-5 nm) treated with a silane coupling agent to produce a composite extreme pressure agent. The mass ratio of helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine, and phosphorus-doped NiMn@CuO / CF was 6:2:0.6:1. The antioxidant was a mixture of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:2.

[0125] (2) A composite extreme pressure agent, a detergent dispersant, a defoamer, a viscosity index improver, and nano-copper treated with a silane coupling agent are mixed in a mass ratio of 1:6:4:1:0.5 to obtain a composite additive, wherein the detergent dispersant is composed of polyisobutylene succinate and alkyl salicylate; and the viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0126] (3) The composite additive, hydroxylated poly-α-olefin and methylcyclopentane are uniformly mixed in a mass ratio of 0.1:1:3 to obtain the anti-pitting corrosion automobile transmission lubricant.

[0127] The lubricating oils obtained in Examples 1-6 and Comparative Examples 1-3 were tested. The kinematic viscosity of the lubricating oils was tested according to GB / T 265, the anti-wear performance of the lubricating oils was tested by the four-ball tester method, and the anti-pitting effect of the lubricating oils was tested by the FVA 54 anti-micropitting test. The results are shown in the following table.

[0128]

[0129] The other components and operations of the anti-pitting automotive transmission lubricant and its preparation method according to the embodiments of the present invention are well known to those skilled in the art and will not be described in detail here. When the embodiments provide numerical ranges, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. The described performance can be achieved within the ratio range of the present invention. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs.

[0130] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a pitting-resistant automobile transmission lubricant, characterized in that: The following steps are involved: (1) mixing helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester and filtering, and mixing the filtrate, an antioxidant and phosphorus-doped NiMn@CuO / CF treated with a first coupling agent to obtain a composite extreme pressure agent; (2) mixing a composite extreme pressure agent, a detergent dispersant, a defoaming agent, a viscosity index improver, and nano-copper treated with a second coupling agent to obtain a composite additive; (3) The composite additive, hydroxylated polyalphaolefin and methylcyclopentane are uniformly mixed in a mass ratio of (0.1-0.3):1:(2-3) to obtain the anti-pitting corrosion automobile transmission lubricant.

2. The method according to claim 1, characterized in that The phosphorus-doped NiMn@CuO / CF is in the shape of a nanosphere with a particle size of 2 to 5 nm; the length of the helical carbon nanotube is 15 to 35 nm and the diameter is 10 to 20 nm.

3. The method according to claim 1, characterized in that In the composite extreme pressure agent, the mass ratio of the helical carbon nanotubes, 2,5-bis(octyldithio)thiadiazole, pentaerythritol tetraborate triethanolamine ester and phosphorus-doped NiMn@CuO / CF is 6:(2-3):(0.6-1.2):(1-2).

4. The method according to claim 1, wherein In the step (1): First, 2,5-bis(octyldithio)thiadiazole and pentaerythritol tetraborate triethanolamine ester are mixed evenly and heated to 120-140°C; Then, the acidified helical carbon nanotubes are added and mixed, and vacuum treatment is performed for 30 to 50 minutes; Then fill it with inert gas to release the vacuum, let it stand and return to room temperature before filtering; The filtrate and the antioxidant are evenly mixed, and then the phosphorus-doped NiMn@CuO / CF treated with the first coupling agent is added to obtain a composite extreme pressure agent.

5. The method according to claim 1, wherein In the step (1), the synthesis step of pentaerythritol tetraborate triethanolamine ester includes: Pentaerythritol is dissolved in toluene, boric acid and tetrabutyl titanate are added, and the mixture is heated to reflux temperature under an inert atmosphere and reacted for 4 to 6 hours. After the reaction is completed, the solvent is removed by distillation under reduced pressure to obtain a pentaerythritol tetraborate intermediate. The pentaerythritol tetraborate intermediate is dissolved in ethanol, triethanolamine is added, and then the temperature is raised to 60-80° C. and reacted for 2-3 hours. After the reaction is completed, the ethanol is removed by reduced pressure distillation to obtain pentaerythritol tetraborate triethanolamine ester.

6. The method according to any one of claims 1 to 5, characterized in that In the step (2), the mass ratio of the composite extreme pressure agent, the detergent dispersant, the defoaming agent, the viscosity index improver and the nano-copper treated with the second coupling agent is (1-4):(4-6):(4-6):(0.5-1):(0.5-1).

7. The method according to claim 6, characterized in that The first coupling agent is selected from one of titanate, silane coupling agent and phosphate ester, and the second coupling agent is selected from one of titanate, silane coupling agent and phosphate ester. The first coupling agent and the second coupling agent are different in components.

8. The method according to claim 6, characterized in that The antioxidant is a mixture of dilauryl thiodipropionate and nonyldiphenylamine in a mass ratio of 1:

2.

9. The method according to claim 6, characterized in that The detergent dispersant is selected from two of polyisobutylene succinimide, polyisobutylene succinate and alkyl salicylate; The viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

10. An anti-pitting automobile transmission lubricant, characterized in that: The method according to any one of claims 1 to 9 is used for preparation.

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