An anti-wear and friction-reducing composite lubricating oil, its preparation method and application

Abstract

The present invention relates to the technical field of lubricating oils, and particularly relates to an anti-wear and friction-reducing composite lubricating oil, a preparation method thereof and an application. The anti-wear and friction-reducing composite lubricating oil is prepared from the following raw materials: base oil, extreme pressure anti-wear agent, preservative, antioxidant, viscosity index improver and dispersant; the extreme pressure anti-wear agent is obtained by modifying layered molybdenum oxide with a metal micelle formed by dodecylamine and moisture, followed by hydrothermal treatment and sulfidation. The anti-wear and friction-reducing composite lubricating oil prepared by the present invention has excellent anti-wear and friction-reducing effects and extreme pressure properties, is suitable for lubrication requirements under high loads and harsh conditions, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating oils, and particularly to an anti-wear and friction-reducing composite lubricating oil and its preparation method and application. Background Art

[0002] Lubricating oils play a crucial role in modern industrial and mechanical applications. With the development of mechanical equipment towards high load, high speed, and high precision, the performance requirements for lubricating oils are also getting higher and higher. Traditional lubricating oils are prone to failure under extreme conditions, leading to increased equipment wear, energy consumption, and even equipment failures. Therefore, the development of lubricating oils with excellent anti-wear and friction-reducing effects and extreme pressure performance has become a current research hotspot.

[0003] Extreme pressure anti-wear agents are key additives in lubricating oils and can provide additional protection under high load conditions. They form a protective film on the friction surface through chemical reactions, enhancing the load-bearing capacity and stability of the oil film. However, the existing extreme pressure anti-wear agents have limited protection ability under high load conditions and cannot significantly improve the extreme pressure performance of lubricating oils. This results in less than ideal performance of lubricating oils in high load applications, and equipment is prone to wear and failure. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an anti-wear and friction-reducing composite lubricating oil and its preparation method and application to meet the lubrication requirements under high load and harsh conditions.

[0005] Based on the above purpose, the present invention provides an anti-wear and friction-reducing composite lubricating oil, which is prepared from the following raw materials by weight: 60 - 80 parts of base oil, 2 - 4 parts of extreme pressure anti-wear agent, 0.5 - 1 part of preservative, 1 - 3 parts of antioxidant, 1 - 3 parts of viscosity index improver, and 1 - 2 parts of dispersant;

[0006] Further, the preparation method of the extreme pressure anti-wear agent is as follows:

[0007] (1) Add dodecylamine to a mixed solution of deionized water and ethanol, stir for 10 - 30 min, then add cerium nitrate hexahydrate and layered molybdenum oxide, continue to stir for 20 - 40 min, and then carry out hydrothermal reaction at 230 - 250 °C for 20 - 28 h, wash, and dry to obtain modified layered molybdenum oxide;

[0008] (2) Mix the modified layered molybdenum oxide and sublimed sulfur, ball mill for 1 - 3 h to obtain a mixture, under an argon atmosphere, heat from room temperature to 750 - 850 °C at a rate of 1 - 10 °C / min, calcine for 2 - 4 h, cool down, and grind to obtain the extreme pressure anti-wear agent.

[0009] Preferably, in the step (1), the weight ratio of dodecylamine, deionized water, ethanol, cerium nitrate hexahydrate and layered molybdenum oxide is 9-24:400-600:70-130:2-6:5-15.

[0010] Preferably, in the step (2), the weight ratio of the modified layered molybdenum oxide and sublimed sulfur is 1:1.5-3.

[0011] Preferably, the base oil is a mixture of polyalphaolefin PAO4 and polyalphaolefin PAO6 in a weight ratio of 5:1-3.

[0012] Preferably, the preservative is benzotriazole.

[0013] Preferably, the antioxidant is a phenolic antioxidant.

[0014] Preferably, the viscosity index improver is polymethacrylate or ethylene-propylene copolymer.

[0015] Preferably, the dispersant is polyisobutenyl succinimide.

[0016] Preferably, the preparation method of the layered molybdenum oxide is as follows: Add sodium molybdate dihydrate and sodium chloride to deionized water, stir for 20-40 min, then adjust the pH to 2-3 using an aqueous hydrochloric acid solution, carry out a hydrothermal reaction at 170-190 °C for 20-28 h, naturally cool to room temperature, wash, and dry to obtain layered molybdenum oxide.

[0017] Preferably, the weight ratio of sodium molybdate dihydrate, sodium chloride and deionized water is 9-27:4-15:300-700.

[0018] Preferably, the concentration of the aqueous hydrochloric acid solution is 1-5 mol / L.

[0019] Furthermore, the present invention also provides a preparation method of an anti-wear and friction-reducing composite lubricating oil, comprising the following steps: Heat the base oil to 150 °C, then add an extreme pressure anti-wear agent, a preservative, an antioxidant, a viscosity index improver and a dispersant, stir for 20-40 min, and cool down to obtain the anti-wear and friction-reducing composite lubricating oil.

[0020] Furthermore, the present invention also provides an application of the anti-wear and friction-reducing composite lubricating oil, which can be used for lubrication under high load and harsh conditions.

[0021] The beneficial effects of the present invention:

[0022] By adding extreme pressure and anti-wear agents, the invention significantly reduces the wear scar diameter from 472.4 μm to 192.6 μm, showing excellent anti-wear and friction-reducing effects. At the same time, the maximum non-seizure load reaches 720 N, which is 45.5% higher than that of the lubricating oil without extreme pressure and anti-wear agents, significantly enhancing the performance of the lubricating oil under high load conditions.

[0023] Compared with traditional layered molybdenum oxide, the extreme pressure and anti-wear agent provided by the invention further improves the anti-wear and friction-reducing effects and extreme pressure performance of the lubricating oil. In addition, the sulfidation treatment of sublimed sulfur plays an important role in improving the anti-wear and friction-reducing effects of the lubricating oil, especially in enhancing the extreme pressure performance, demonstrating the importance of sulfidation treatment in optimizing the performance of lubricating oils.

[0024] The dodecylamine and cerium-modified layered molybdenum oxide adopted by the invention significantly improve the anti-wear and friction-reducing effects and extreme pressure performance of the lubricating oil. The mechanism is that the metal ion micelles formed by dodecylamine and cerium can intercalate and adsorb on the inner and outer surfaces of the layered molybdenum oxide, and carbon particles doped with cerium are formed after hydrothermal treatment, enhancing the adsorption ability of the layered molybdenum oxide on the friction surface and the interlayer slip.

[0025] In summary, the anti-wear and friction-reducing composite lubricating oil of the invention has excellent anti-wear and friction-reducing effects and extreme pressure performance, is suitable for lubrication requirements under high load and harsh conditions, and has broad application prospects. Specific Embodiments

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in detail with reference to specific embodiments.

[0027] Example 1:

[0028] (1) Add 9 g of sodium molybdate dihydrate and 4 g of sodium chloride to 300 g of deionized water, stir for 20 min, then adjust the pH to 2.1 using hydrochloric acid with a concentration of 5 mol / L, and then transfer it to a reaction kettle. Carry out hydrothermal reaction at 170 °C for 20 h. After naturally cooling to room temperature, wash it three times with deionized water and ethanol respectively, and finally dry it at 80 °C for 12 h to obtain layered molybdenum oxide;

[0029] (2) Add 9 g of dodecylamine to a mixed solution of 400 g of deionized water and 70 g of ethanol, stir for 10 min, then add 2 g of cerium nitrate hexahydrate and 5 g of layered molybdenum oxide, continue to stir for 20 min, and then transfer it to a hydrothermal reaction kettle. Carry out hydrothermal reaction at 230 °C for 20 h, wash it three times with deionized water and ethanol respectively, and finally dry it at 80 °C for 12 h to obtain modified layered molybdenum oxide;

[0030] (3) Mix 10 g of modified layered molybdenum oxide and 15 g of sublimed sulfur, ball mill for 1 h at a ball mill rotation speed of 20 rpm to obtain a mixed material, then transfer it to a tube furnace, and under an argon atmosphere, heat from room temperature to 750 °C at a rate of 1 °C / min, calcine for 2 h, cool down, and grind to obtain an extreme pressure and anti-wear agent;

[0031] (4) Heat 50 g of poly-α-olefin PAO4 and 10 g of poly-α-olefin PAO6 to 150 °C, then add 2 g of extreme pressure and anti-wear agent, 0.5 g of benzotriazole, 1 g of antioxidant 264, 1 g of viscosity index improver HSD-TZ0009, and 1 g of dispersant T154A, stir for 20 min, cool down to obtain an anti-wear and friction-reducing composite lubricating oil.

[0032] Example 2:

[0033] (1) Add 18.15 g of sodium molybdate dihydrate and 9 g of sodium chloride to 500 g of deionized water, stir for 30 min, then adjust the pH to 2.5 using hydrochloric acid with a concentration of 5 mol / L, and then transfer it to a reaction kettle, carry out a hydrothermal reaction at 180 °C for 24 h. After naturally cooling to room temperature, wash it 3 times with deionized water and ethanol respectively, and finally dry it at 80 °C for 12 h to obtain layered molybdenum oxide;

[0034] (2) Add 18.5 g of dodecylamine to a mixed solution of 500 g of deionized water and 100 g of ethanol, stir for 20 min, then add 4.3 g of cerium nitrate hexahydrate and 10 g of layered molybdenum oxide, continue to stir for 30 min, then transfer it to a hydrothermal reaction kettle, carry out a hydrothermal reaction at 240 °C for 24 h, wash it 3 times with deionized water and ethanol respectively, and finally dry it at 80 °C for 12 h to obtain modified layered molybdenum oxide;

[0035] (3) Mix 10 g of modified layered molybdenum oxide and 20 g of sublimed sulfur, ball mill for 2 h at a ball mill rotation speed of 20 rpm to obtain a mixed material, then transfer it to a tube furnace, and under an argon atmosphere, heat from room temperature to 800 °C at a rate of 5 °C / min, calcine for 3 h, cool down, and grind to obtain an extreme pressure and anti-wear agent;

[0036] (4) Heat 50 g of poly-α-olefin PAO4 and 20 g of poly-α-olefin PAO6 to 150 °C, then add 3 g of extreme pressure and anti-wear agent, 0.8 g of benzotriazole, 2 g of antioxidant 264, 2 g of viscosity index improver HSD-TZ0009, and 1.5 g of dispersant T154A, stir for 30 min, cool down to obtain an anti-wear and friction-reducing composite lubricating oil.

[0037] Example 3:

[0038] (1) Add 27 g of sodium molybdate dihydrate and 15 g of sodium chloride to 700 g of deionized water, stir for 40 min, then adjust the pH to 3 using 1 mol / L hydrochloric acid, transfer to a reaction kettle, carry out hydrothermal reaction at 190 °C for 28 h, naturally cool to room temperature, wash three times with deionized water and ethanol respectively, and finally dry at 80 °C for 12 h to obtain layered molybdenum oxide;

[0039] (2) Add 24 g of dodecylamine to a mixed solution of 600 g of deionized water and 130 g of ethanol, stir for 30 min, add 6 g of cerium nitrate hexahydrate and 15 g of layered molybdenum oxide, continue to stir for 40 min, then transfer to a hydrothermal reaction kettle, carry out hydrothermal reaction at 250 °C for 28 h, wash three times with deionized water and ethanol respectively, and finally dry at 80 °C for 12 h to obtain modified layered molybdenum oxide;

[0040] (3) Mix 10 g of modified layered molybdenum oxide and 30 g of sublimed sulfur, ball mill for 3 h at a ball mill rotation speed of 20 rpm to obtain a mixture, then transfer to a tubular furnace, under an argon atmosphere, heat from room temperature to 850 °C at a rate of 10 °C / min, calcine for 4 h, cool down, and grind to obtain an extreme pressure and anti-wear agent;

[0041] (4) Heat 50 g of polyalphaolefin PAO4 and 30 g of polyalphaolefin PAO6 to 150 °C, then add 4 g of extreme pressure and anti-wear agent, 1 g of benzotriazole, 3 g of antioxidant 264, 3 g of viscosity index improver HSD-TZ0009, and 2 g of dispersant T154A, stir for 40 min, cool down to obtain an anti-wear and friction-reducing composite lubricating oil.

[0042] Comparative Example 1:

[0043] The difference between Comparative Example 1 and Example 2 is that: in step (4), the extreme pressure and anti-wear agent is replaced with layered molybdenum oxide;

[0044] The specific steps are as follows:

[0045] (1) Add 18.15 g of sodium molybdate dihydrate and 9 g of sodium chloride to 500 g of deionized water, stir for 30 min, then adjust the pH to 2.5 using 5 mol / L hydrochloric acid, transfer to a reaction kettle, carry out hydrothermal reaction at 180 °C for 24 h, naturally cool to room temperature, wash three times with deionized water and ethanol respectively, and finally dry at 80 °C for 12 h to obtain layered molybdenum oxide;

[0046] (2) Heat 50 g of polyalphaolefin PAO4 and 20 g of polyalphaolefin PAO6 to 150 °C, then add 3 g of layered molybdenum oxide, 0.8 g of benzotriazole, 2 g of antioxidant 264, 2 g of viscosity index improver HSD-TZ0009, and 1.5 g of dispersant T154A, stir for 30 min, cool down to obtain a lubricating oil.

[0047] Comparative Example 2:

[0048] The difference between Comparative Example 2 and Example 2 is that: the extreme pressure and anti-wear agent in step (4) is replaced by modified layered molybdenum oxide;

[0049] The specific steps are as follows:

[0050] (1) Add 18.15 g of sodium molybdate dihydrate and 9 g of sodium chloride to 500 g of deionized water, stir for 30 min, then adjust the pH to 2.5 using hydrochloric acid with a concentration of 5 mol / L, transfer to a reaction kettle, carry out hydrothermal reaction at 180 °C for 24 h, after natural cooling to room temperature, wash 3 times with deionized water and ethanol respectively, and finally dry at 80 °C for 12 h to obtain layered molybdenum oxide;

[0051] (2) Add 18.5 g of dodecylamine to a mixed solution of 500 g of deionized water and 100 g of ethanol, stir for 20 min, then add 4.3 g of cerium nitrate hexahydrate and 10 g of layered molybdenum oxide, continue to stir for 30 min, then transfer to a hydrothermal reaction kettle, carry out hydrothermal reaction at 240 °C for 24 h, wash 3 times with deionized water and ethanol respectively, and finally dry at 80 °C for 12 h to obtain modified layered molybdenum oxide;

[0052] (3) Heat 50 g of polyalphaolefin PAO4 and 20 g of polyalphaolefin PAO6 to 150 °C, then add 3 g of modified layered molybdenum oxide, 0.8 g of benzotriazole, 2 g of antioxidant 264, 2 g of viscosity index improver HSD-TZ0009 and 1.5 g of dispersant T154A, stir for 30 min, cool down to obtain lubricating oil.

[0053] Comparative Example 3:

[0054] The difference between Comparative Example 3 and Example 2 is that: cerium nitrate hexahydrate is not added in step (2);

[0055] The specific steps are as follows:

[0056] (1) Add 18.15 g of sodium molybdate dihydrate and 9 g of sodium chloride to 500 g of deionized water, stir for 30 min, then adjust the pH to 2.5 using hydrochloric acid with a concentration of 5 mol / L, transfer to a reaction kettle, carry out hydrothermal reaction at 180 °C for 24 h, after natural cooling to room temperature, wash 3 times with deionized water and ethanol respectively, and finally dry at 80 °C for 12 h to obtain layered molybdenum oxide;

[0057] (2) Add 18.5 g of dodecylamine to a mixed solution of 500 g of deionized water and 100 g of ethanol, stir for 20 min, then add 10 g of layered molybdenum oxide, continue to stir for 30 min, then transfer to a hydrothermal reactor, carry out hydrothermal reaction at 240 °C for 24 h, wash 3 times with deionized water and ethanol respectively, and finally dry at 80 °C for 12 h to obtain modified layered molybdenum oxide;

[0058] (3) Mix 10 g of modified layered molybdenum oxide and 20 g of sublimed sulfur, ball mill for 2 h, and the rotation speed of the ball mill is 20 rpm to obtain a mixed material, then transfer to a tubular furnace, under an argon atmosphere, heat from room temperature to 800 °C at a rate of 5 °C / min, calcine for 3 h, cool down, and grind to obtain an extreme pressure and anti-wear agent;

[0059] (4) Heat 50 g of poly-α-olefin PAO4 and 20 g of poly-α-olefin PAO6 to 150 °C, then add 3 g of extreme pressure and anti-wear agent, 0.8 g of benzotriazole, 2 g of antioxidant 264, 2 g of viscosity index improver HSD-TZ0009, and 1.5 g of dispersant T154A, stir for 30 min, cool down to obtain a lubricating oil.

[0060] Comparative Example 4:

[0061] The difference between Comparative Example 4 and Example 2 is that: dodecylamine was not added in step (2);

[0062] The specific steps are as follows:

[0063] (1) Add 18.15 g of sodium molybdate dihydrate and 9 g of sodium chloride to 500 g of deionized water, stir for 30 min, then use hydrochloric acid with a concentration of 5 mol / L to adjust the pH to 2.5, and then transfer to a reaction kettle, carry out hydrothermal reaction at 180 °C for 24 h, naturally cool to room temperature, wash 3 times with deionized water and ethanol respectively, and finally dry at 80 °C for 12 h to obtain layered molybdenum oxide;

[0064] (2) Add 4.3 g of cerium nitrate hexahydrate and 10 g of layered molybdenum oxide to a mixed solution of 500 g of deionized water and 100 g of ethanol, stir for 30 min, then transfer to a hydrothermal reactor, carry out hydrothermal reaction at 240 °C for 24 h, wash 3 times with deionized water and ethanol respectively, and finally dry at 80 °C for 12 h to obtain modified layered molybdenum oxide;

[0065] (3) Mix 10 g of modified layered molybdenum oxide and 20 g of sublimed sulfur, ball mill for 2 h, and the rotation speed of the ball mill is 20 rpm to obtain a mixed material, then transfer to a tubular furnace, under an argon atmosphere, heat from room temperature to 800 °C at a rate of 5 °C / min, calcine for 3 h, cool down, and grind to obtain an extreme pressure and anti-wear agent;

[0066] (4) Heat 50 g of polyalphaolefin PAO4 and 20 g of polyalphaolefin PAO6 to 150 °C, then add 3 g of extreme pressure and anti-wear agent, 0.8 g of benzotriazole, 2 g of antioxidant 264, 2 g of viscosity index improver HSD-TZ0009, and 1.5 g of dispersant T154A, stir for 30 min, and cool down to obtain lubricating oil.

[0067] Comparative Example 5:

[0068] The difference between Comparative Example 5 and Example 2 is that: in step (4), no extreme pressure and anti-wear agent is added;

[0069] The specific steps are as follows:

[0070] Heat 50 g of polyalphaolefin PAO4 and 20 g of polyalphaolefin PAO6 to 150 °C, then add 0.8 g of benzotriazole, 2 g of antioxidant 264, 2 g of viscosity index improver HSD-TZ0009, and 1.5 g of dispersant T154A, stir for 30 min, and cool down to obtain lubricating oil.

[0071] Performance test:

[0072] Anti-wear performance: Use a four-ball wear tester to evaluate the anti-wear performance of the compound oil according to the standard ASTM D4172-21. The diameter of the test steel balls is 12.7 mm, and the Rockwell hardness is 64. Fix three 12.7-mm steel balls together, immerse the lubricating oil in the steel balls, and press the top ball into the cavity formed by the three clamped balls with a force of 147 N for three-point contact. After setting the temperature to 75 °C, the top ball rotates at a speed of 1200 r / min for 60 min, and measure the wear scar diameter on the three lower steel balls. The results are shown in Table 1.

[0073] Extreme pressure performance: Use the standard ASTM D2783-21 to test the extreme pressure performance of the compound oil. The rotational speed is 1760 r / min, the temperature of the machine and the test lubricating oil ranges from 18 °C to 35 °C, and then the test is carried out under increasing load until welding occurs. The load at which welding occurs is the maximum non-seizure load. The results are shown in Table 1.

[0074] Table 1 Performance test results

[0075]

[0076] Data analysis:

[0077] It can be seen from the data of Examples 1-3 and Comparative Example 5 in Table 1 that the anti-wear and friction-reducing composite lubricating oil prepared by the present invention has excellent anti-wear and friction-reducing effects and extreme pressure performance. Compared with the lubricating oil without extreme pressure anti-wear agent, the wear scar diameter is reduced from 472.4 μm to 192.6 μm, and the maximum non-seizure load can reach 720 N, which is increased by 45.5% compared with the lubricating oil without extreme pressure anti-wear agent.

[0078] It can be seen from the data of Example 2 and Comparative Example 1 in Table 1 that the extreme pressure anti-wear agent provided by the present invention further improves the anti-wear and friction-reducing effects and extreme pressure performance of the lubricating oil compared with traditional layered molybdenum oxide.

[0079] It can be seen from the data of Example 2 and Comparative Example 2 in Table 1 that the sulfidation treatment of sublimed sulfur helps to improve the anti-wear and friction-reducing effects of the lubricating oil, especially the extreme pressure performance.

[0080] It can be seen from the data of Example 2 and Comparative Examples 3-4 in Table Ⅰ that dodecylamine and cerium can synergistically improve the anti-wear and friction-reducing effects and extreme pressure performance of the lubricating oil. This is mainly because the metal ion micelles formed by dodecylamine and cerium can intercalate and adsorb on the inner and outer surfaces of layered molybdenum oxide, and carbon particles doped with cerium are formed after hydrothermal treatment, which improves the adsorption of layered molybdenum oxide on the friction surface and the slip between layers.

[0081] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is exemplary only and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. An anti-wear and friction-reducing composite lubricating oil, characterized in that, It is prepared from the following raw materials by weight parts: 60 - 80 parts of base oil, 2 - 4 parts of extreme pressure and anti-wear agent, 0.5 - 1 part of preservative, 1 - 3 parts of antioxidant, 1 - 3 parts of viscosity index improver and 1 - 2 parts of dispersant; The preparation method of the extreme pressure and anti-wear agent is as follows: (1) Add dodecylamine into the mixed solution of deionized water and ethanol, stir for 10 - 30 min, then add cerium nitrate hexahydrate and layered molybdenum oxide, continue to stir for 20 - 40 min, then carry out hydrothermal reaction at 230 - 250 °C for 20 - 28 h, wash and dry to obtain modified layered molybdenum oxide; (2) Mix the modified layered molybdenum oxide and sublimed sulfur, ball mill for 1 - 3 h to obtain a mixture. Under an argon atmosphere, heat from room temperature to 750 - 850 °C at a rate of 1 - 10 °C / min, calcine for 2 - 4 h, cool down and grind to obtain the extreme pressure and anti-wear agent; In the step (1), the weight ratio of dodecylamine, deionized water, ethanol, cerium nitrate hexahydrate and layered molybdenum oxide is 9 - 24:400 - 600:70 - 130:2 - 6:5 - 15; In the step (2), the weight ratio of the modified layered molybdenum oxide and sublimed sulfur is 1:1.5 - 3.

2. The anti-wear and friction-reducing composite lubricating oil according to claim 1, wherein The base oil is a mixture of polyalphaolefin PAO4 and polyalphaolefin PAO6 with a weight ratio of 5:1 - 3.

3. The anti-wear and friction-reducing composite lubricating oil according to claim 1, wherein The preservative is benzotriazole.

4. The anti-wear and friction-reducing composite lubricating oil according to claim 1, wherein The antioxidant is a phenolic antioxidant.

5. The anti-wear and friction-reducing composite lubricating oil according to claim 1, characterized in that, The viscosity index improver is polymethacrylate or ethylene-propylene copolymer.

6. The anti-wear and friction-reducing composite lubricating oil according to claim 1, wherein, The dispersant is polyisobutenyl succinimide.

7. The anti-wear and friction-reducing composite lubricating oil according to claim 1, wherein The preparation method of the layered molybdenum oxide is as follows: Add sodium molybdate dihydrate and sodium chloride into deionized water, stir for 20 - 40 min, then adjust the pH to 2 - 3 with hydrochloric acid aqueous solution, carry out hydrothermal reaction at 170 - 190 °C for 20 - 28 h, naturally cool to room temperature, wash and dry to obtain layered molybdenum oxide.

8. The anti-wear and friction-reducing composite lubricating oil according to claim 7, characterized in that, The weight ratio of sodium molybdate dihydrate, sodium chloride and deionized water is 9 - 27:4 - 15:300 - 7M00.

9. The anti-wear and friction-reducing composite lubricating oil according to claim 7, wherein The concentration of the hydrochloric acid aqueous solution is 1 - 5 mol / L.

10. A method for preparing the anti-wear and friction-reducing composite lubricating oil according to any one of claims 1-9, characterized in that, It includes the following steps: Heat the base oil to 150 °C, then add the extreme pressure and anti-wear agent, preservative, antioxidant, viscosity index improver and dispersant, stir for 20 - 40 min, cool down to obtain the anti-wear and friction-reducing compound lubricating oil.

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