Anti-attrition lubricating oil suitable for minimal quantity lubrication and preparation method of anti-attrition lubricating oil

Abstract

The invention discloses anti-attrition lubricating oil suitable for minimal quantity lubrication and a preparation method thereof, and belongs to the technical field of lubricating oil, molybdenum disulfide is nucleated and grows on the surface of porous cerium oxide nanosphere powder to form a cerium oxide and molybdenum disulfide compound, then modified silicon dioxide and tannic acid are pre-polymerized to form silicon dioxide prepolymer powder, and the silicon dioxide prepolymer powder is subjected to ball milling to obtain the anti-attrition lubricating oil suitable for minimal quantity lubrication. The preparation method comprises the following steps: taking a cerium oxide molybdenum disulfide compound as a core material, taking silicon dioxide prepolymer powder and an N-isopropylacrylamide polymer as a shell to obtain a composite temperature-sensitive microcapsule, and mixing the composite temperature-sensitive microcapsule with other raw materials to prepare the composite temperature-sensitive microcapsule. The outer-layer shell polymer chain of the composite temperature-sensitive microcapsule in the anti-attrition lubricating oil shrinks, the cerium oxide molybdenum disulfide compound inside is released, and controllable release of the inner core material is realized by using the temperature sensitivity of the shell polymer of the composite temperature-sensitive microcapsule and the external temperature change during operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of lubricating oils, and particularly relates to an anti-wear lubricating oil suitable for minimum quantity lubrication and a preparation method thereof. Background Art

[0002] Minimum quantity lubrication technology (MQL) has been rapidly developed in the fields of high-speed machining and energy conservation and environmental protection in recent years. Its core lies in achieving efficient lubrication through a small amount of lubricant, thereby reducing the impact on the environment and improving the machining efficiency at the same time. Its core principle is to mix compressed gas with a very small amount of lubricating oil to form micron-sized droplets or suspended oil mists, which are sprayed onto the cutting area at high speed to achieve the effects of lubrication, cooling, and chip removal. For example, research shows that when stearic acid is added to the base oil, reverse wettability can be formed, and the minimum quantity lubricating oil is distributed in the form of oil droplets, thereby achieving the effect of enhancing lubrication.

[0003] The Chinese invention patent application with the publication number CN109810761B discloses a degradable minimum quantity lubricating oil and a preparation method thereof, which has good extreme pressure anti-wear property, rust prevention property, and good biodegradability. It can completely or partially replace traditional extreme pressure anti-wear agents containing chlorine, sulfur, and phosphorus and be used in degradable minimum quantity lubricating oils. A small amount of degradable minimum quantity lubricating oil can meet the requirements of lubrication cooling, extreme pressure anti-wear, and rust prevention in metal processing.

[0004] There are problems with insufficient oil film strength and poor extreme pressure ability in minimum quantity lubricating oils. Especially during cutting operations, a large amount of frictional heat will be generated due to the friction between the tool and the workpiece. At the same time, the pressure will increase when the tool face contacts the cutting surface. Under high temperature and high pressure conditions, the oil film of the anti-wear lubricating oil is more likely to rupture, unable to effectively isolate the friction surface, resulting in direct contact between metal micro-protrusions and aggravating wear. Summary of the Invention

[0005] The purpose of the present invention is to provide an anti-wear lubricating oil suitable for minimum quantity lubrication and a preparation method thereof. By generating molybdenum disulfide on the surface of porous cerium oxide nanosphere powder to obtain a cerium oxide molybdenum disulfide composite, and then polymerizing modified silica powder containing amino groups with tannic acid and N-isopropylacrylamide to form a shell, a composite thermosensitive microcapsule is prepared using the cerium oxide molybdenum disulfide composite as the core material, and then the composite thermosensitive microcapsule is mixed with other raw materials to solve the problem that the oil film is easily broken and the lubrication effect cannot be achieved under high temperature and high pressure conditions, and achieve the effect of releasing the core material of the composite thermosensitive microcapsule for lubrication under high temperature and high pressure conditions.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A preparation method of an anti-wear lubricating oil suitable for minimum quantity lubrication, comprising the following steps: Step 1: Using ammonium molybdate tetrahydrate as the molybdenum source and thiourea as the sulfur source, molybdenum disulfide is generated on the surface of the porous cerium oxide nanosphere powder to obtain a cerium oxide-molybdenum disulfide composite.

[0007] Step 2: Graft a silane coupling agent containing an amino group onto the surface of the silica powder to obtain modified silica powder, and then polymerize the modified silica powder and tannic acid to obtain a silica prepolymer powder.

[0008] Step 3: Using the cerium oxide-molybdenum disulfide composite as the core material, polymerize the silica prepolymer powder and N-isopropylacrylamide to form a shell to obtain a composite thermosensitive microcapsule, and then mix lacceroic acid, octyldodecanol, phosphorus pentasulfide, ammonium phosphomolybdate, triethanolamine, maleic acid castor oil ester and the composite thermosensitive microcapsule to prepare an anti-friction lubricating oil suitable for minimum quantity lubrication.

[0009] Furthermore, the porous cerium oxide nanosphere powder is prepared by the following steps: Add cerium nitrate hexahydrate powder, deionized water, propionic acid and ethylene glycol into a reaction kettle, react at 180 - 190 °C, a pressure of 45 - 50 MPa and a rotation speed of 500 - 800 r / min for 3 - 4 h, cool to room temperature, filter, wash, and dry to obtain the porous cerium oxide nanosphere powder.

[0010] Furthermore, the dosage ratio of cerium nitrate hexahydrate powder, deionized water, propionic acid and ethylene glycol is 20 - 30 g : 20 - 35 mL : 20 - 30 mL : 400 - 450 mL.

[0011] Furthermore, the cerium oxide-molybdenum disulfide composite is prepared by the following steps: Add ammonium molybdate tetrahydrate, thiourea, polyvinylpyrrolidone and deionized water into a reaction kettle, mix evenly, then add the porous cerium oxide nanosphere powder, and keep the temperature at 180 °C and react at 500 - 800 r / min for 16 - 18 h, cool to room temperature, filter, wash, and dry to obtain the cerium oxide-molybdenum disulfide composite.

[0012] Furthermore, the dosage ratio of ammonium molybdate tetrahydrate, thiourea, polyvinylpyrrolidone, deionized water and the porous cerium oxide nanosphere powder is 25 - 30 g : 50 - 60 g : 100 - 150 g : 2.5 - 3.5 L : 15 - 20 g.

[0013] Furthermore, the silica prepolymer powder is prepared by the following steps: Add the modified silica powder and the tannic acid aqueous solution with a concentration of 0.5 mol / L into a reaction kettle, ultrasonically disperse for 15 - 20 min, adjust the pH value to 8 - 9 with sodium hydroxide, react for 6 h under the conditions of 50 - 60 °C and 300 - 500 r / min, filter, wash, and freeze-dry to obtain the silica prepolymer powder.

[0014] Furthermore, the dosage ratio of the modified silica powder to the tannic acid aqueous solution is 0.5 - 1 g : 50 - 60 mL.

[0015] Furthermore, the composite thermosensitive microcapsules are prepared by the following steps: Mix the cerium oxide molybdenum disulfide composite and the N-isopropylacrylamide solution with a concentration of 0.08 mol / L evenly, then transfer them to a high-gravity rotating packed bed. Add the aqueous ammonium persulfate solution with a concentration of 0.368 mol / L in a nitrogen atmosphere, react for 10 - 15 min, add the silica prepolymer powder, react for 2 - 3 h, quickly cool, filter, wash, and freeze-dry to obtain the composite thermosensitive microcapsules.

[0016] Furthermore, the dosage ratio of the cerium oxide molybdenum disulfide composite, the N-isopropylacrylamide solution, the aqueous ammonium persulfate solution, and the silica prepolymer powder is 5 - 6 g : 4.9 - 5 L : 50 - 60 mL : 0.5 - 1 g.

[0017] Furthermore, the mass ratio of aleuritic acid, octyldodecanol, phosphorus pentasulfide, ammonium phosphomolybdate, triethanolamine, maleic acid castor oil ester, and the composite thermosensitive microcapsules is 10 - 12 : 8 - 9 : 0.5 - 0.6 : 1.5 - 2 : 1 - 1.5 : 80 - 90 : 20 - 30.

[0018] The beneficial effects of the present invention: 1. The anti-friction lubricating oil suitable for minimum quantity lubrication in the present invention is prepared by first nucleating and growing molybdenum disulfide on the surface of porous cerium oxide nanosphere powder to form a cerium oxide-molybdenum disulfide composite, then pre-polymerizing modified silica and tannic acid to form silica prepolymer powder, and then using the cerium oxide-molybdenum disulfide composite as the core material and the silica prepolymer powder and N-isopropylacrylamide polymer as the shell to obtain composite thermosensitive microcapsules, which are then mixed with other raw materials. During the cutting operation, the frictional heat between the tool and the workpiece will cause the temperature to rise, and the outer shell polymer chains of the composite thermosensitive microcapsules in the anti-friction lubricating oil will shrink, releasing the internal cerium oxide-molybdenum disulfide composite. The controlled release of the internal core material is achieved by utilizing the thermosensitivity of the composite thermosensitive microcapsule shell polymer and the change of the external temperature during the operation. At the same time, the high pressure generated on the friction surface during the cutting operation can accelerate the outflow of the internal core material. The cerium oxide-molybdenum disulfide composite can form a continuous lubricating film when rubbing against the metal surface, isolating the direct contact between metals and achieving a good lubricating effect under high temperature and high pressure conditions.

[0019] 2. In the present invention, the cerium oxide-molybdenum disulfide composite is first prepared by using cerium nitrate hexahydrate powder as the cerium source to obtain nanoscale porous cerium oxide nanosphere powder with a positive charge on the surface, and then hydrolyzing ammonium molybdate tetrahydrate to produce MoO4 2- with a negative charge, which attracts the positive charge on the surface of the porous cerium oxide nanosphere powder. Then, using thiourea as the sulfur source, under high temperature and high pressure conditions, the generated molybdenum disulfide will nucleate and grow on the surface of the porous cerium oxide nanosphere powder to form a cerium oxide-molybdenum disulfide composite, which can load a large amount of molybdenum disulfide on the surface of the porous cerium oxide nanosphere. Molybdenum disulfide has a layered structure of sulfur-molybdenum-sulfur, and the monolayers are connected by weak van der Waals forces and are extremely prone to interlayer slip, thus exhibiting a good lubricating effect. Cerium oxide can inhibit the oxidation of molybdenum disulfide, not only improving the lubricating effect but also delaying the oxidation time.

[0020] 3. In the present invention, the silica prepolymer powder is first grafted with an amino-containing silane coupling agent on the surface of nanoscale silica powder. Since tannic acid has abundant hydroxyl groups on its surface, hydrogen bond networks are formed using the amino groups and the hydroxyl groups on the surface of tannic acid, and silica and tannic acid are reacted and polymerized to obtain it. Then, under the action of the initiator ammonium persulfate, a cross-linked network is formed between the silica prepolymer powder and N-isopropylacrylamide in a hydrogen bond binding manner, and the cerium oxide-molybdenum disulfide composite is coated inside. The polymer shell formed by the silica prepolymer powder and N-isopropylacrylamide has higher strength, which is due to the high strength characteristic of silica itself, thus increasing the mechanical strength of the composite thermosensitive microcapsule shell and enabling the function of dual response to temperature and pressure. Detailed implementation mode

[0021] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0022] Embodiment 1: This embodiment provides an anti-friction lubricating oil suitable for minimum quantity lubrication, which is prepared by the following steps: S1: Add 20 g of cerium nitrate hexahydrate powder, 20 mL of deionized water, 20 mL of propionic acid, and 400 mL of ethylene glycol into a reaction kettle, react at 180 °C, a pressure of 45 MPa, and a rotation speed of 500 r / min for 3 h, cool to room temperature, centrifuge and filter for 10 min, wash the filter cake with deionized water and ethanol three times, and dry to constant weight at 80 °C to obtain porous cerium oxide nanosphere powder.

[0023] S2: Add 25 g of ammonium molybdate tetrahydrate, 50 g of thiourea, 100 g of polyvinylpyrrolidone, and 2.5 L of deionized water into a reaction kettle, stir at 300 r / min for 1 h, then add 15 g of porous cerium oxide nanosphere powder, ultrasonically treat for 15 min, keep the temperature at 180 °C and a rotation speed of 500 r / min for heat preservation reaction for 16 h. The surface of the porous cerium oxide nanosphere powder has a positive charge, and MoO4 produced after the hydrolysis of ammonium molybdate tetrahydrate 2- has a negative charge, and the positive and negative charges attract each other. MoO4 2- will preferentially bind to the surface of the porous cerium oxide nanosphere powder. Then, using thiourea as a sulfur source, under high temperature and high pressure conditions, molybdenum disulfide nucleates and grows on the surface of the porous cerium oxide nanosphere powder. Cool to room temperature, centrifuge and filter at 8000 r / min, wash the filter cake with deionized water and absolute ethanol alternately three times, and vacuum dry at 60 °C for 12 h to obtain a cerium oxide molybdenum disulfide composite.

[0024] S3: Add 10 mL of deionized water, 10 mL of silane coupling agent KH-550, and 130 mL of absolute ethanol into a reaction kettle, hydrolyze at 500 r / min for 30 min, then add 15 g of silicon dioxide powder with a particle size of 10 - 30 nm, 15 mL of deionized water, and 75 mL of absolute ethanol, adjust the pH value to 5 with glacial acetic acid, react at 60 °C and 500 r / min for 8 h, graft KH-550 containing amino groups onto silicon dioxide to form Si-O-Si bonds, cool to room temperature, vacuum filter, wash the filter cake with deionized water and absolute ethanol twice respectively, dry at 70 °C for 12 h, and grind to obtain modified silicon dioxide powder.

[0025] S4: Add 0.5 g of modified silica powder and 50 mL of tannic acid aqueous solution with a concentration of 0.5 mol / L as a crosslinking agent into a reaction kettle, ultrasonically disperse for 15 min, adjust the pH value to 8 with sodium hydroxide, react at 50 °C and 300 r / min for 6 h, the phenolic hydroxyl group of tannic acid and the amino group of modified silica form a hydrogen bond network, centrifuge and filter, wash the filter cake with deionized water until it is neutral, and freeze-dry to obtain silica prepolymer powder.

[0026] S5: Add 5 g of cerium oxide molybdenum disulfide composite and 4.9 L of N-isopropylacrylamide solution with a concentration of 0.08 mol / L into a reaction kettle and mix evenly, then transfer it to a high gravity rotating packed bed, purge with nitrogen for 30 min at 70 °C and 2000 r / min to remove oxygen, then add 50 mL of ammonium persulfate aqueous solution with a concentration of 0.368 mol / L, react for 10 min, add 0.5 g of silica prepolymer powder, react for 2 h, using tannic acid as an intermediate, silica prepolymer powder and N-isopropylacrylamide form a crosslinked network in the form of hydrogen bond binding on the surface of the cerium oxide molybdenum disulfide composite to become a shell, wrap the cerium oxide molybdenum disulfide composite in the shell, quench in an ice-water bath, centrifuge and filter, wash twice with deionized water, and freeze-dry to obtain composite thermosensitive microcapsules.

[0027] S6: Add 10 g of laccaic acid and 8 g of octyldodecanol into a reaction kettle, slowly add 0.5 g of phosphorus pentasulfide while stirring, react at 130 °C and 500 r / min for 2 h, then add 1.5 g of ammonium phosphomolybdate, react for 3 h, reduce the pressure to remove water and ammonia, add 1 g of triethanolamine at 90 °C, mix evenly, cool to room temperature, then add 80 g of maleic castor oil ester and 20 g of composite thermosensitive microcapsules, and mix evenly to obtain an anti-friction lubricating oil suitable for minimum quantity lubrication.

[0028] Example 2: This example provides an anti-friction lubricating oil suitable for minimum quantity lubrication, which is prepared by the following steps: S1: Add 25 g of cerium nitrate hexahydrate powder, 27 mL of deionized water, 25 mL of propionic acid and 425 mL of ethylene glycol into a reaction kettle, react at 185 °C, a pressure of 47 MPa and a rotation speed of 650 r / min for 3.5 h, cool to room temperature, centrifuge and filter for 12 min, wash the filter cake 4 times with deionized water and ethanol, and dry to constant weight at 85 °C to obtain porous cerium oxide nanosphere powder.

[0029] S2: Add 27.5 g of ammonium molybdate tetrahydrate, 55 g of thiourea, 125 g of polyvinylpyrrolidone, and 3 L of deionized water into a reaction kettle, stir for 1.25 h under the condition of 400 r / min, then add 17.5 g of porous cerium oxide nanosphere powder, ultrasonically treat for 17.5 min, and keep the temperature at 180 °C and stir at 650 r / min for 17 h. The surface of the porous cerium oxide nanosphere powder is positively charged, and MoO4 produced after the hydrolysis of ammonium molybdate tetrahydrate 2- is negatively charged, and the positive and negative charges attract each other. MoO4 2- will preferentially bind to the surface of the porous cerium oxide nanosphere powder. Then, using thiourea as the sulfur source, under high temperature and high pressure conditions, molybdenum disulfide nucleates and grows on the surface of the porous cerium oxide nanosphere powder. Cool to room temperature, centrifuge and filter under the condition of 8000 r / min, wash the filter cake 4 times alternately with deionized water and absolute ethanol, and vacuum dry at 70 °C for 13 h to obtain a cerium oxide molybdenum disulfide composite.

[0030] S3: Add 12.5 mL of deionized water, 12.5 mL of silane coupling agent KH-550, and 140 mL of absolute ethanol into a reaction kettle, hydrolyze for 35 min under the condition of 650 r / min, then add 17.5 g of silica powder with a particle size of 10 - 30 nm, 17.5 mL of deionized water, and 87.5 mL of absolute ethanol, adjust the pH value to 5 with glacial acetic acid, and react at 70 °C and 650 r / min for 10 h to graft KH-550 containing amino groups onto silica to form Si-O-Si bonds. Cool to room temperature, vacuum filter, wash the filter cake 2 times respectively with deionized water and absolute ethanol, and dry at 75 °C for 12 h, then grind to obtain modified silica powder.

[0031] S4: Add 0.7 g of modified silica powder and 55 mL of 0.5 mol / L tannic acid aqueous solution as a crosslinking agent into a reaction kettle, ultrasonically disperse for 17 min, adjust the pH value to 8 with sodium hydroxide, and react at 55 °C and 400 r / min for 6 h. The phenolic hydroxyl groups of tannic acid and the amino groups of modified silica form a hydrogen bond network. Centrifuge and filter, wash the filter cake with deionized water until it is neutral, and freeze-dry to obtain silica prepolymer powder.

[0032] S5: Add 5.5 g of cerium oxide molybdenum disulfide complex and 5 L of N-isopropylacrylamide solution with a concentration of 0.08 mol / L into a reaction kettle, mix them evenly, then transfer them to a high-gravity rotating packed bed. Purge with nitrogen for 30 min at 75 °C and 2500 r / min to remove oxygen. Then add 55 mL of ammonium persulfate aqueous solution with a concentration of 0.368 mol / L, react for 12 min, add 0.7 g of silica prepolymer powder, react for 2.5 h. Using tannic acid as an intermediate, the silica prepolymer powder and N-isopropylacrylamide form a cross-linked network on the surface of the cerium oxide molybdenum disulfide complex in the form of hydrogen bonding to become a shell, wrapping the cerium oxide molybdenum disulfide complex in the shell. Quench in an ice-water bath, centrifuge and filter, wash 3 times with deionized water, and dry by freeze-drying to obtain composite thermosensitive microcapsules.

[0033] S6: Add 11 g of aleuritic acid and 8.5 g of octyldodecanol into a reaction kettle, slowly add 0.55 g of phosphorus pentasulfide while stirring, react at 135 °C and 650 r / min for 2 h, then add 1.75 g of ammonium phosphomolybdate, react for 3.5 h, reduce the pressure to remove moisture and ammonia. Add 1.25 g of triethanolamine at 95 °C, mix evenly, cool to room temperature, then add 85 g of maleic castor oil ester and 25 g of composite thermosensitive microcapsules, mix evenly to obtain an anti-wear lubricating oil suitable for minimum quantity lubrication.

[0034] Example 3: This example provides an anti-wear lubricating oil suitable for minimum quantity lubrication, which is prepared by the following steps:

[0035] S1: Add 30 g of cerium nitrate hexahydrate powder, 35 mL of deionized water, 30 mL of propionic acid and 450 mL of ethylene glycol into a reaction kettle, react at 190 °C, a pressure of 50 MPa and a rotation speed of 800 r / min for 4 h, cool to room temperature, centrifuge and filter for 15 min, wash the filter cake 5 times with deionized water and ethanol, and dry to constant weight at 90 °C to obtain porous cerium oxide nanosphere powder.

[0036] S2: Add 30 g of ammonium molybdate tetrahydrate, 60 g of thiourea, 150 g of polyvinylpyrrolidone and 3.5 L of deionized water into a reaction kettle, stir at 500 r / min for 1.5 h, then add 20 g of porous cerium oxide nanosphere powder, ultrasonically treat for 20 min, and keep the temperature at 180 °C and react at 800 r / min for 18 h. The surface of the porous cerium oxide nanosphere powder is positively charged, and MoO4 produced after hydrolysis of ammonium molybdate tetrahydrate 2- is negatively charged, and the positive and negative charges attract each other. MoO4 2-It will preferentially bind to the surface of the porous cerium oxide nanosphere powder. Then, using thiourea as a sulfur source, under high temperature and high pressure conditions, molybdenum disulfide nucleates and grows on the surface of the porous cerium oxide nanosphere powder. After cooling to room temperature, it is centrifuged and filtered at 8000 r / min. The filter cake is washed alternately with deionized water and absolute ethanol 5 times, and then vacuum dried at 80 °C for 14 h to obtain a cerium oxide-molybdenum disulfide composite.

[0037] S3: Add 15 mL of deionized water, 15 mL of silane coupling agent KH-550, and 150 mL of absolute ethanol into a reaction kettle, hydrolyze for 40 min at 800 r / min, then add 20 g of silicon dioxide powder with a particle size of 10 - 30 nm, 20 mL of deionized water, and 100 mL of absolute ethanol. Adjust the pH value to 6 with glacial acetic acid, and react for 12 h at 80 °C and 800 r / min to graft KH-550 containing amino groups onto silicon dioxide to form Si-O-Si bonds. After cooling to room temperature, it is vacuum filtered. The filter cake is washed 3 times with deionized water and absolute ethanol respectively, and then dried at 80 °C for 12 h and ground to obtain modified silicon dioxide powder.

[0038] S4: Add 1 g of modified silicon dioxide powder and 60 mL of a 0.5 mol / L aqueous solution of tannic acid as a crosslinking agent into a reaction kettle, ultrasonically disperse for 20 min, adjust the pH value to 9 with sodium hydroxide, and react for 6 h at 60 °C and 500 r / min. The phenolic hydroxyl groups of tannic acid and the amino groups of modified silicon dioxide form a hydrogen bond network. Centrifuge and filter, wash the filter cake with deionized water until it is neutral, and freeze-dry to obtain silicon dioxide prepolymer powder.

[0039] S5: Add 6 g of cerium oxide-molybdenum disulfide composite and 5.1 L of a 0.08 mol / L N-isopropylacrylamide solution into a reaction kettle and mix evenly. Then transfer it to a high-gravity rotating packed bed, purge with nitrogen for 30 min at 80 °C and 3000 r / min to remove oxygen, then add 60 mL of a 0.368 mol / L aqueous solution of ammonium persulfate, react for 15 min, add 1 g of silicon dioxide prepolymer powder, and react for 3 h. Using tannic acid as an intermediate, silicon dioxide prepolymer powder and N-isopropylacrylamide form a crosslinked network in the form of hydrogen bond binding on the surface of the cerium oxide-molybdenum disulfide composite to become a shell, and the cerium oxide-molybdenum disulfide composite is wrapped in the shell. Quench it in an ice-water bath, centrifuge and filter, wash it 4 times with deionized water, and freeze-dry to obtain composite thermosensitive microcapsules.

[0040] S6: Add 12 g of laccaic acid and 9 g of octyldodecanol into a reaction kettle, slowly add 0.6 g of phosphorus pentasulfide while stirring, react for 2 h under the conditions of 140 °C and 800 r / min, then add 2 g of ammonium phosphomolybdate, react for 4 h, evacuate moisture and ammonia under reduced pressure, add 1.5 g of triethanolamine under the condition of 100 °C, mix evenly, cool to room temperature, then add 90 g of maleic castor oil ester and 30 g of composite thermosensitive microcapsules, mix evenly to obtain an anti-wear lubricating oil suitable for minimum quantity lubrication.

[0041] Comparative Example 1: On the basis of Example 1, remove the composite thermosensitive microcapsules in step S6, and keep the other steps unchanged to prepare an anti-wear lubricating oil suitable for minimum quantity lubrication.

[0042] Comparative Example 2: On the basis of Example 1, replace the silica prepolymer powder with tannic acid in step S5, and keep the other steps unchanged to prepare an anti-wear lubricating oil suitable for minimum quantity lubrication.

[0043] Comparative Example 3: On the basis of Example 1, replace the composite thermosensitive microcapsules with the cerium oxide molybdenum disulfide composite prepared in step S2 in step S6, and keep the other steps unchanged to prepare an anti-wear lubricating oil suitable for minimum quantity lubrication.

[0044] Perform performance tests on the anti-wear lubricating oils suitable for minimum quantity lubrication prepared in Examples 1 - 3 and Comparative Examples 1 - 3: Coefficient of friction: Refer to SH / T 0762 - 2005 "Lubricating Oil Friction Coefficient Measurement Method (Four-Ball Method)". The experimental equipment uses a lever four-ball friction testing machine produced by Jinan Hengke Testing Equipment Co., Ltd. Immerse four test steel balls, upper and lower ball fixtures, and an oil cup in n-heptane for 1 min, then clean them with an ultrasonic cleaner for 10 s. Repeat the rinsing with acetone. After the required equipment is clean and dry, install three clean test steel balls, add lubricating oil to cover the top of the steel balls by at least 3 mm. Install the oil cup on the testing machine and slowly apply a test load of 392 N to avoid impact. Turn on the heater switch and heat the test oil temperature to 75 ± 2 °C. Then start the motor to rotate the steel balls at a speed of 600 r / min for 60 min. Conduct the experiment three times and take the average value.

[0045] Anti-wear performance: Refer to SH / T 0189 - 92 "Lubricating Oil Anti-wear Performance Measurement Method (Four-Ball Machine Method)". The experimental equipment uses a lever four-ball friction testing machine produced by Jinan Hengke Testing Equipment Co., Ltd. Select a load of 392 N and adjust the rotation speed to 1200 r / min. Under these parameter conditions, perform long-term grinding for 60 min. After the experiment, wash the three fixed balls in the oil box with acetone, and observe the three fixed balls with an optical reading microscope. Judge the wear performance of the used lubricant based on the average wear scar diameter (WSD) of the three fixed balls.

[0046] Oxidation resistance: The anti-friction lubricating oil suitable for minimum quantity lubrication prepared in Examples 1-3 and Comparative Examples 1-3 was filled into an oxidation tube, placed in a heating bath and heated to 95 °C, and air dried under constant pressure was introduced for oxidation. The oxidation time was 312 h. After the oxidation was completed, the sample was taken out of the heating bath and cooled to room temperature. The viscosity increase value and precipitation value of the sample at 100 °C before and after oxidation were measured.

[0047] Table 1 Summary of performance tests of anti-friction lubricating oil

[0048] As can be seen from Table 1, the friction coefficients and wear scar diameters in Examples 1-3 were the smallest, those in Comparative Example 1 were the largest, the friction coefficients and wear scar diameters in Comparative Example 2 were slightly lower than those in Comparative Example 1, and the friction coefficients and wear scar diameters in Comparative Example 3 were lower than those in Comparative Example 2. In Comparative Example 1, the composite thermosensitive microcapsules were removed in step S6, indicating that the anti-friction lubricating oil added with composite thermosensitive microcapsules had a good lubricating effect under high temperature and high pressure conditions. In step S5 of Comparative Example 2, tannic acid was used instead of the silica prepolymer powder, and in step S6 of Comparative Example 3, the cerium oxide molybdenum disulfide complex prepared in step S2 was used instead of the composite thermosensitive microcapsules, indicating that the cerium oxide molybdenum disulfide complex enhanced the lubrication effect of the anti-friction lubricating oil under high temperature and high pressure conditions, and the addition of silica to the composite thermosensitive microcapsules also played a certain enhancing role.

[0049] The viscosity increase value and precipitation value at 100 °C in Examples 1-3 were the lowest, and those in Comparative Example 1 were the highest. In Comparative Example 1, the composite thermosensitive microcapsules were removed in step S6, indicating that the anti-friction lubricating oil added with composite thermosensitive microcapsules had the best antioxidant performance. In step S5 of Comparative Example 2, tannic acid was used instead of the silica prepolymer powder, and its antioxidant performance decreased, indicating that the silica prepolymer powder played a certain antioxidant role in the anti-friction lubricating oil. In step S6 of Comparative Example 3, the cerium oxide molybdenum disulfide complex prepared in step S2 was used instead of the composite thermosensitive microcapsules, indicating that the antioxidant performance of the cerium oxide molybdenum disulfide complex without a shell coating decreased, but its antioxidant performance was better than that of the lubricating oil without adding composite thermosensitive microcapsules.

[0050] It should be noted that in this article, terms such as "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0051] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A preparation method of an anti-wear lubricating oil suitable for minimum quantity lubrication, characterized in that, It includes the following steps: Step 1: Using ammonium molybdate tetrahydrate as the molybdenum source and thiourea as the sulfur source, molybdenum disulfide is generated on the surface of the porous cerium oxide nanosphere powder to obtain a cerium oxide-molybdenum disulfide composite; Step 2: Grafting a silane coupling agent containing an amino group onto the surface of the silica powder to obtain a modified silica powder, and then polymerizing the modified silica powder and tannic acid to obtain a silica prepolymer powder; Step 3: Using the cerium oxide-molybdenum disulfide composite as the core material, polymerizing the silica prepolymer powder and N-isopropylacrylamide to form a shell to obtain a composite thermosensitive microcapsule, and then mixing laccaic acid, octyldodecanol, phosphorus pentasulfide, ammonium phosphomolybdate, triethanolamine, castor oil maleate and the composite thermosensitive microcapsule to prepare an anti-friction lubricating oil suitable for minimum quantity lubrication.

2. The preparation method of an anti-wear lubricating oil applicable to minimum quantity lubrication according to claim 1, characterized in that, The porous cerium oxide nanosphere powder described in Step 1 is specifically prepared through the following steps: Adding cerium nitrate hexahydrate powder, deionized water, propionic acid and ethylene glycol into a reaction kettle, reacting at 180 - 190 °C, a pressure of 45 - 50 MPa and a rotation speed of 500 - 800 r / min for 3 - 4 h, cooling to room temperature, filtering, washing and drying to obtain the porous cerium oxide nanosphere powder.

3. The preparation method of an anti-wear lubricating oil applicable to minimum quantity lubrication according to claim 2, characterized in that The dosage ratio of the cerium nitrate hexahydrate powder, deionized water, propionic acid and ethylene glycol is 20 - 30 g : 20 - 35 mL : 20 - 30 mL : 400 - 450 mL.

4. The preparation method of an anti-friction lubricating oil applicable to minimum quantity lubrication according to claim 1, characterized in that, The cerium oxide-molybdenum disulfide composite described in Step 1 is specifically prepared through the following steps: Adding ammonium molybdate tetrahydrate, thiourea, polyvinylpyrrolidone and deionized water into a reaction kettle, mixing evenly, then adding the porous cerium oxide nanosphere powder, and carrying out a heat preservation reaction at 180 °C and 500 - 800 r / min for 16 - 18 h, cooling to room temperature, filtering, washing and drying to obtain the cerium oxide-molybdenum disulfide composite.

5. The preparation method of an anti-wear lubricating oil suitable for minimum quantity lubrication according to claim 4, characterized in that, The dosage ratio of the ammonium molybdate tetrahydrate, thiourea, polyvinylpyrrolidone, deionized water and the porous cerium oxide nanosphere powder is 25 - 30 g : 50 - 60 g : 100 - 150 g : 2.5 - 3.5 L : 15 - 20 g.

6. The preparation method of an anti-friction lubricating oil suitable for minimum quantity lubrication according to claim 1, characterized in that The silica prepolymer powder described in Step 2 is specifically prepared through the following steps: Adding the modified silica powder and a 0.5 mol / L aqueous tannic acid solution into a reaction kettle, ultrasonically dispersing for 15 - 20 min, adjusting the pH value to 8 - 9 with sodium hydroxide, reacting at 50 - 60 °C and 300 - 500 r / min for 6 h, filtering, washing and freeze-drying to obtain the silica prepolymer powder.

7. The preparation method of an anti-friction lubricating oil applicable to minimum quantity lubrication according to claim 6, characterized in that, The dosage ratio of the modified silica powder and the tannic acid aqueous solution is 0.5 - 1 g : 50 - 60 mL.

8. The preparation method of an anti-friction lubricating oil applicable to minimum quantity lubrication according to claim 1, wherein The composite thermosensitive microcapsule described in Step 3 is specifically prepared through the following steps: The cerium oxide molybdenum disulfide composite and an N-isopropylacrylamide solution with a concentration of 0.08 mol / L are mixed evenly and then transferred to a high-gravity rotating packed bed. An aqueous ammonium persulfate solution with a concentration of 0.368 mol / L is added under a nitrogen atmosphere, and the reaction is carried out for 10 - 15 min. Then, silica prepolymer powder is added, and the reaction is carried out for 2 - 3 h. After rapid cooling, filtration, washing, and freeze-drying, composite thermosensitive microcapsules are obtained.

9. The preparation method of an anti-friction lubricating oil suitable for minimum quantity lubrication according to claim 8, characterized in that, The dosage ratio of the cerium oxide molybdenum disulfide composite, the N-isopropylacrylamide solution, the aqueous ammonium persulfate solution, and the silica prepolymer powder is 5 - 6 g: 4.9 - 5 L: 50 - 60 mL: 0.5 - 1 g.

10. The preparation method of an anti-friction lubricating oil suitable for minimum quantity lubrication according to claim 1, characterized in that, The mass ratio of aleuritic acid, octyldodecanol, phosphorus pentasulfide, ammonium phosphomolybdate, triethanolamine, ricinoleic acid maleate, and the composite thermosensitive microcapsules is 10 - 12: 8 - 9: 0.5 - 0.6: 1.5 - 2: 1 - 1.5: 80 - 90: 20 - 30.

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