Wear-resistant lubricating oil and preparation method thereof

Abstract

The invention discloses wear-resistant lubricating oil and a preparation method thereof, and relates to the technical field of lubricating oil, the wear-resistant lubricating oil comprises the following components in percentage by mass: 2.5% of wear-resistant additive and the balance of base oil; the preparation method of the wear-resistant additive comprises the following steps: pre-treating wollastonite, then preparing a 3-aminopropyltriethoxysilane absolute ethyl alcohol solution with the mass fraction of 5-8% by taking absolute ethyl alcohol as a solvent, mixing the pre-treated wollastonite with the 3-aminopropyltriethoxysilane absolute ethyl alcohol solution to react, and after the reaction is finished, drying, grinding, refining and sieving to obtain modified wollastonite; gypsum powder is dissolved in glycerin to form a mixed oil solution, the modified wollastonite is added into the mixed oil solution to be stirred, then the mixed oil solution is subjected to an ultrasonic stirring reaction under UV irradiation, grinding and sieving are conducted after vacuum filtration and drying are conducted, the wear-resistant additive is obtained, the obtained wear-resistant additive has good dispersing performance in base oil, and the obtained wear-resistant lubricating oil is very small in average friction coefficient and good in wear resistance. And the wear-resisting performance is high.

Description

Technical Field

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

[0002] Mechanical lubricants refer to lubricating materials used in various mechanical equipment to reduce friction loss, lower temperature, prevent oxidation, prevent corrosion and clean the surface of the machine. Lubricants must have excellent lubrication properties to reduce friction and wear inside mechanical equipment and extend the life of the machine. Mechanical equipment is prone to generate heat during operation, and lubricants can take away some of the heat to keep the mechanical equipment at a normal operating temperature. Lubricants also have good anti-rust and anti-corrosion properties, which can prevent metal parts from being affected by oxidation and corrosion. Mechanical equipment is prone to generate high temperatures during operation, and lubricants have good high temperature resistance and can maintain normal lubrication properties even at high temperatures. Lubricants are widely used in various mechanical equipment, such as automobiles, ships, aircraft, generators, hydraulic systems, gearboxes, bearings, etc.

[0003] The main components of lubricating oil include base oil and additives. The base oil determines the basic properties of the lubricating oil, and is mainly divided into three categories: mineral base oil, synthetic base oil and bio-based oil. Additives are the essence of modern advanced lubricating oil, which can make up for and improve the deficiencies in the performance of the base oil and give it certain new properties. In the prior art, in order to ensure the sealing performance of mechanical seals, friction and wear are inevitable between the tightly fitting end faces. Severe wear causes the mechanical seal end faces to lose performance. Therefore, the lubricating oil used for mechanical seals needs to have higher wear resistance, and the additives that need to be added to the base oil are often wear-resistant additives with wear resistance.

[0004] However, the wear-resistant additives in current wear-resistant lubricants are difficult to disperse evenly in the base oil and have insufficient wear-resistant performance, which has become a huge challenge in the industry. Summary of the invention

[0005] The purpose of the present invention is to provide a wear-resistant lubricating oil and a preparation method thereof, so as to solve the following technical problems: How to improve the wear resistance of wear-resistant lubricants.

[0006] The purpose of the present invention can be achieved through the following technical solutions: In a first aspect, the present invention discloses a wear-resistant lubricating oil, wherein the wear-resistant lubricating oil component comprises 2.5% by mass of a wear-resistant additive, and the remainder is base oil.

[0007] The wear-resistant additive comprises the following raw materials in parts by weight: 20-30 parts of wollastonite, 1-2 parts of 3-aminopropyltriethoxysilane, 8-10 parts of glycerol, and 1-2 parts of gypsum powder; Preferably, wollastonite is 22-25 parts, 3-aminopropyltriethoxysilane is 1.2-1.8 parts, glycerin is 8.5-9.5 parts, and gypsum powder is 1.2-1.8 parts.

[0008] More preferably, wollastonite is 23 parts, 3-aminopropyltriethoxysilane is 1.5 parts, glycerin is 9 parts, and gypsum powder is 1.5 parts.

[0009] Furthermore, the preparation method of the wear-resistant additive is: S1: Pre-treat the wollastonite and grind it to a size of 500-600 mesh. The specific steps are as follows: S11: First, clean and dry wollastonite is placed in a grinder for preliminary crushing, and the particle size of the wollastonite after preliminary crushing is 100-200 mesh, and then dried at 80° C. for 1-2 hours; S12: Add the wollastonite after preliminary crushing into a planetary ball mill, and ball mill it at a ball mill speed of 300r / min for 24h. After the ball milling is completed, dry the wollastonite at 80℃ for 3-4h, and then transfer it to a grinder for grinding and refining. After sieving, obtain wollastonite with a specification of 500-600 mesh. At this time, the wollastonite is spherical in shape.

[0010] Furthermore, during the 24-hour ball milling process, the direction of rotation was changed every 4 hours, and the rotation was stopped for 30 minutes to cool the material to room temperature. This interval was not included in the ball milling time.

[0011] S2: using anhydrous ethanol as a solvent, preparing an anhydrous ethanol solution of 3-aminopropyl triethoxysilane with a mass fraction of 5%-8%, mixing the pretreated wollastonite with the anhydrous ethanol solution of 3-aminopropyl triethoxysilane for reaction, drying, grinding and sieving after the reaction to obtain modified wollastonite; wherein the method for mixing the pretreated wollastonite with the anhydrous ethanol solution of 3-aminopropyl triethoxysilane is: The pretreated wollastonite was added into a ball mill, and an anhydrous ethanol solution of 3-aminopropyltriethoxysilane was added dropwise into the ball mill using a rubber-tipped dropper. The ball mill was reacted for 30 hours at a ball mill speed of 300 r / min, thereby grafting 3-aminopropyltriethoxysilane onto the surface of the wollastonite, modifying the surface of the wollastonite, enhancing the lipophilicity of the wollastonite, and improving the dispersibility of the wollastonite in the base oil.

[0012] Furthermore, during the 30-hour ball milling process, the direction of rotation was changed every 3 hours, and the rotation was stopped for 30 minutes to cool the material to room temperature. This interval was not included in the ball milling time.

[0013] S3: dissolving gypsum powder in glycerol to form a mixed oil solution, adding modified wollastonite to the mixed oil solution, stirring at 60°C for 1 hour, then placing under UV irradiation for ultrasonic stirring for 4-5 hours, vacuum filtering and drying for 24 hours, grinding and sieving to obtain a wear-resistant additive; the specific operation steps are as follows: S31: dissolving gypsum powder in glycerol to form an oil-mixed solution, placing the oil-mixed solution in a water bath and heating it to 60° C., then keeping it warm, adding modified wollastonite and stirring it magnetically for 1 hour to evenly disperse the modified wollastonite in the oil-mixed solution, and obtaining solution A; S32: Solution A is transferred to an ultrasonic agitator, a UV lamp is arranged above the ultrasonic agitator, and the solution is ultrasonically stirred for reaction for 4-5 hours under UV irradiation to obtain solution B; under the catalytic action of UV, the gypsum powder is evenly embedded in the 3-aminopropyltriethoxysilane film layer on the surface of wollastonite, so that the gypsum powder is evenly adsorbed on the surface of the modified wollastonite. The gypsum powder is rich in sulfur-containing compounds, which can impart sulfur elements to the surface of wollastonite to enhance its wear resistance.

[0014] Furthermore, the UV wavelength used is 365 nm.

[0015] S33: After vacuum filtering and drying Solution B for 24 hours, grind and sieve to obtain a wear-resistant additive.

[0016] Furthermore, the base oil is a light base oil or a synthetic base oil among mineral base oils, preferably a synthetic base oil, such as PAO, POE and other base oils with excellent performance.

[0017] In a second aspect, the present invention also discloses a method for preparing the wear-resistant lubricating oil as described above, which is prepared according to the following steps: adding a lubricating additive to the base oil, first magnetically stirring at 40°C for 2 hours, and then using an ultrasonic cleaner to ultrasonically disperse for 1 hour to obtain the wear-resistant lubricating oil.

[0018] Beneficial effects of the present invention: 1. The wear-resistant lubricating oil of the present invention is prepared by mixing a base oil and a wear-resistant additive. Among the wear-resistant additives, wollastonite with good wear-resistant and lubricating properties is used as a base material. Wollastonite is a silicate mineral that is cheap and easy to obtain and has low cost. Its molecular structure contains a large number of Si-O bonds and Al-O bonds, and these bond structures are stable, and can form mineral crystals with relatively large hardness and good stability. There are also many effective functional groups such as oxides and hydroxyls on its surface, and these functional groups can form physical forces with the metal surface to reduce the friction coefficient. After the wollastonite is refined by pretreatment, on the one hand, the particle size of the wollastonite is reduced, which is beneficial to improving the dispersibility in the base oil. More importantly, after grinding, the wollastonite is transformed from an irregular polygon into a spherical shape, which is beneficial to transforming sliding friction into rolling friction and can promote the formation of a lubricating film, thereby improving the wear resistance.

[0019] 2. The wear-resistant additive in the wear-resistant lubricating oil of the present invention is surface-modified by 3-aminopropyltriethoxysilane. 3-aminopropyltriethoxysilane is grafted onto the surface of wollastonite, which can enhance the lipophilicity of wollastonite and improve the dispersibility of wollastonite in base oil.

[0020] 3. The wear-resistant additive in the wear-resistant lubricating oil of the present invention is surface-modified by 3-aminopropyltriethoxysilane, and gypsum powder is also introduced. Gypsum powder is rich in sulfur-containing compounds, which can impart sulfur elements on the surface of wollastonite, so that the wear-resistant lubricating oil can form a lubricating film containing elements such as Si, O, and S on the wear surface during the action process, thereby improving the friction environment between the friction surfaces, increasing the contact surface, reducing the friction coefficient, and improving the wear resistance. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

[0023] Preparation Example 1 Preparation of wear-resistant additives.

[0024] Step 1: Take 20g of wollastonite, wash it and place it in an electric blast drying oven to dry it at 80℃ for 40min, then transfer it to a grinder to crush it and pass it through a 200-mesh sieve. Pour the unscreened wollastonite into a grinder and grind and sieve it until it passes through a 200-mesh sieve; then place the sieved wollastonite in an electric blast drying oven to dry it at 80℃ for 1.5h, then transfer it to a zirconia ball mill in a planetary ball mill, add 400g of grinding balls with a particle size of 4mm, and ball mill at 300r / min. Change the direction every 4h of ball milling, and stop for 30min. The interval is not included in the ball milling time. The ball milling is completed after 24h of ball milling, and then the wollastonite is placed in an electric blast drying oven to dry it at 80℃ for 3.5h, then transferred to a grinder for grinding and refining, and passed through a 600-mesh sieve to obtain the pretreated wollastonite.

[0025] Step 2: Add 19g of anhydrous ethanol to a beaker, and then add 1g of 3-aminopropyltriethoxysilane and stir evenly to obtain a 3-aminopropyltriethoxysilane anhydrous ethanol solution with a mass fraction of 5%; add the wollastonite obtained in step 1 to the zirconia ball mill in the planetary ball mill, and then add 600g of grinding balls with a particle size of 4mm, and ball mill at 300r / min. During the ball milling process, use a rubber-tipped dropper to add the 3-aminopropyltriethoxysilane anhydrous ethanol solution dropwise, change the direction every 3h of ball milling, and stop for 30min. The interval is not included in the ball milling time. The ball milling is completed after 30h of ball milling, and then transferred to an electric hot air drying oven to dry at 80°C for 2h, and then transferred to a grinder for grinding and refining, and the modified wollastonite is obtained after passing through a 500-mesh sieve.

[0026] Step 3: Add 8g glycerol and 1g gypsum powder into a beaker, stir evenly to form an oil-mixed solution, transfer the water beaker containing the oil-mixed solution into a water bath and heat it to 60°C and keep it warm, then add the modified wollastonite in step 2, stir with a magnetic stirrer for 1h to obtain solution A, transfer solution A to an ultrasonic stirrer, arrange a UV lamp above the ultrasonic stirrer, and react at 30Hz ultrasonic stirring for 4.5h under UV irradiation with a wavelength of 365nm to obtain solution B, vacuum filter solution B and dry it for 24h, then grind it through a 500-mesh sieve to obtain a wear-resistant additive.

[0027] Preparation Example 2 Preparation of wear-resistant additives.

[0028] Compared with Preparation Example 1, the only difference is that the amount of each component is different, specifically: 22g of wollastonite, 1.2g of 3-aminopropyltriethoxysilane, 18.8g of anhydrous ethanol, 8.5g of glycerol, and 1.2g of gypsum powder; other conditions are exactly the same, and the wear-resistant additive is finally obtained.

[0029] Preparation Example 3 Preparation of wear-resistant additives.

[0030] Compared with Preparation Example 1, the only difference is that the amount of each component is different, specifically: 23g of wollastonite, 1.5g of 3-aminopropyltriethoxysilane, 23.5g of anhydrous ethanol, 9g of glycerol, and 1.5g of gypsum powder; other conditions are exactly the same, and finally a wear-resistant additive is obtained.

[0031] Preparation Example 4 Preparation of wear-resistant additives.

[0032] Compared with Preparation Example 1, the only difference is that the amount of each component is different, specifically: 25g of wollastonite, 1.8g of 3-aminopropyltriethoxysilane, 20.7g of anhydrous ethanol, 9.5g of glycerol, and 1.8g of gypsum powder; other conditions are exactly the same, and the wear-resistant additive is finally obtained.

[0033] Preparation Example 5 Preparation of wear-resistant additives.

[0034] Compared with Preparation Example 1, the only difference is that the amount of each component is different, specifically: 30g of wollastonite, 2g of 3-aminopropyltriethoxysilane, 23g of anhydrous ethanol, 10g of glycerol, and 2g of gypsum powder; other conditions are exactly the same, and finally a wear-resistant additive is obtained.

[0035] Preparation Comparative Example 1 Preparation of wear-resistant additives.

[0036] Compared with Example 3, the only difference is that step 3 is not performed, and the modified wollastonite obtained in step 2 is directly used as the wear-resistant additive.

[0037] Preparation Comparative Example 2 Preparation of wear-resistant additives.

[0038] Compared with Example 3, the only difference is that step 2 and step 3 are not performed, and the pretreated wollastonite obtained in step 1 is directly used as the wear-resistant additive.

[0039] Preparation Comparative Example 3 Preparation of wear-resistant additives.

[0040] The wollastonite is used directly as a wear-resistant additive without any treatment.

[0041] Example 1 Preparation of wear-resistant lubricating oil.

[0042] Add 97.5 g of PAO base oil to a beaker, and then add 2.5 g of the wear-resistant additive prepared in Preparation Example 1, transfer the beaker to a water bath, heat to 40°C and keep warm, stir with a magnetic stirrer for 2 h, and then transfer to an ultrasonic cleaner for ultrasonic dispersion at 20 Hz for 1 h to obtain a wear-resistant lubricating oil.

[0043] Example 2 Preparation of wear-resistant lubricating oil.

[0044] Compared with Example 1, the only difference is that the wear-resistant lubricant prepared in Preparation Example 1 is replaced by the wear-resistant additive prepared in Preparation Example 2, and other conditions are exactly the same, and finally a wear-resistant lubricating oil is obtained.

[0045] Example 3 Preparation of wear-resistant lubricating oil.

[0046] Compared with Example 1, the only difference is that the wear-resistant lubricant prepared in Preparation Example 1 is replaced by the wear-resistant additive prepared in Preparation Example 3, and other conditions are exactly the same, and finally a wear-resistant lubricating oil is obtained.

[0047] Example 4 Preparation of wear-resistant lubricating oil.

[0048] Compared with Example 1, the only difference is that the wear-resistant lubricant prepared in Preparation Example 1 is replaced by the wear-resistant additive prepared in Preparation Example 4, and other conditions are exactly the same, and finally a wear-resistant lubricating oil is obtained.

[0049] Example 5 Preparation of wear-resistant lubricating oil.

[0050] Compared with Example 1, the only difference is that the wear-resistant lubricant prepared in Preparation Example 1 is replaced by the wear-resistant additive prepared in Preparation Example 5, and other conditions are exactly the same, and finally a wear-resistant lubricating oil is obtained.

[0051] Comparative Example 1 Preparation of wear-resistant lubricating oil.

[0052] Compared with Example 1, the only difference is that the wear-resistant lubricant prepared in Preparation Example 1 is replaced by the wear-resistant additive prepared in Preparation Comparative Example 1, and other conditions are exactly the same, and finally a wear-resistant lubricating oil is obtained.

[0053] Comparative Example 2 Preparation of wear-resistant lubricating oil.

[0054] Compared with Example 1, the only difference is that the wear-resistant lubricant prepared in Preparation Example 1 is replaced by the wear-resistant additive prepared in Preparation Comparative Example 2, and other conditions are exactly the same, and finally a wear-resistant lubricating oil is obtained.

[0055] Comparative Example 3 Preparation of wear-resistant lubricating oil.

[0056] Compared with Example 1, the only difference is that the wear-resistant lubricant prepared in Preparation Example 1 is replaced by the wear-resistant additive prepared in Preparation Comparative Example 3, and other conditions are exactly the same, and finally a wear-resistant lubricating oil is obtained.

[0057] First, the dispersibility of the lubricating additives in the wear-resistant lubricating oils prepared in Examples 1-5 and Comparative Examples 1-3 in the base oil was tested. The test method was as follows: 20 mL of the wear-resistant lubricating oils prepared in Examples 1-5 and Comparative Examples 1-3 were respectively placed in test tubes and numbered, left to stand for a period of time, and the stratification of different density components in the lubricating oils was visually observed. The observations were recorded every 24 hours to determine the dispersion effect. The observation results of the test are listed in Table 1, which is shown below: Table 1

[0058] By analyzing the data in Table 1, it can be seen that after standing for 120 hours, the wear-resistant lubricants prepared in Examples 1-5 showed no precipitation and stratification phenomenon at all, which shows that the wear-resistant lubricant in the wear-resistant lubricant of the present invention has a good dispersion effect in the base oil; Comparative Example 1 showed a trace amount of precipitation for the first time after standing for 120 hours, while Comparative Examples 2-3 were completely precipitated after standing for 72 hours, which shows that the wollastonite modified with 3-aminopropyltriethoxysilane has improved its lipophilicity to a certain extent, and promoted the dispersibility of wollastonite in the base oil.

[0059] Then, the wear-resistant lubricating oils prepared in Examples 1-5 and Comparative Examples 1-3 were tested for wear resistance, and the test method was as follows: The wear test was carried out using a high-temperature multifunctional friction and wear testing machine (MMU-10G) and disc-pin friction. The test pin-disc was assembled and fixed by upper and lower fixtures. The relative speed between the pin and the disc was provided by a driving motor. The lower fixture contained the lubricating oil sample required for the test. The sliding screw was controlled by a computer to move upward to obtain the corresponding test force. The friction coefficient was calculated from the ratio of the friction torque measured by the torque sensor to the test radius.

[0060] The test results are listed in Table 2, which is as follows: Table 2

[0061] Analyzing the data in Table 2, it can be seen that the wear-resistant lubricating oils prepared in Examples 1-5 have significantly smaller average friction coefficients than those in Comparative Examples 1-3, which indicates that the wear-resistant lubricating oils of the present invention have stronger wear resistance; specifically, the average friction coefficient of Comparative Example 1 is significantly lower than that of Example 1, which indicates that the addition of glycerol and gypsum powder can improve the wear resistance of the wear-resistant lubricating oil; the average friction coefficient of Comparative Example 2 is further reduced compared with that of Comparative Example 1, which indicates that wollastonite modified with 3-aminopropyltriethoxysilane can improve the wear resistance of the wear-resistant lubricating oil to a certain extent; the average friction coefficient of Comparative Example 3 is further reduced compared with that of Comparative Example 2, which indicates that pre-treatment of wollastonite to refine the particle size is beneficial to improving the wear resistance of the wear-resistant lubricating oil.

[0062] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A wear-resistant lubricating oil, characterized in that: The wear-resistant lubricating oil component includes 2.5% by mass of wear-resistant additives, and the balance is base oil; The wear-resistant additive comprises the following raw materials in parts by weight: 20-30 parts of wollastonite, 1-2 parts of 3-aminopropyltriethoxysilane, 8-10 parts of glycerol, and 1-2 parts of gypsum powder.

2. The wear-resistant lubricating oil according to claim 1, characterized in that: The preparation method of the wear-resistant additive is: S1: pre-treating wollastonite and grinding the wollastonite to a size of 500-600 mesh; S2: using anhydrous ethanol as a solvent, preparing an anhydrous ethanol solution of 3-aminopropyltriethoxysilane with a mass fraction of 5%-8%, mixing the pretreated wollastonite with the anhydrous ethanol solution of 3-aminopropyltriethoxysilane for reaction, and drying, grinding and sieving after the reaction to obtain modified wollastonite; S3: Dissolve gypsum powder in glycerol to form a mixed oil solution, add modified wollastonite to the mixed oil solution, stir at 60°C for 1 hour, then place under UV irradiation for ultrasonic stirring and reaction for 4-5 hours, vacuum filter and dry for 24 hours, grind and sieve to obtain a wear-resistant additive.

3. The wear-resistant lubricating oil according to claim 2, characterized in that: In step S1, the steps of pre-treating wollastonite are: S11: placing clean and dry wollastonite in a grinder for preliminary crushing, wherein the particle size of the wollastonite after preliminary crushing is 100-200 mesh, and then drying at 80° C. for 1-2 hours; S12: Add the wollastonite after preliminary crushing into a planetary ball mill, and ball mill it at a ball mill speed of 300r / min for 24h. After ball milling, dry the wollastonite at 80°C for 3-4h, and then transfer it to a grinder for grinding and refining. After sieving, obtain wollastonite with a specification of 500-600 mesh.

4. The wear-resistant lubricating oil according to claim 3, characterized in that: In step S12, during the 24-hour ball milling process, the direction of rotation is changed every 4 hours, and the rotation is paused for 30 minutes, and this interval is not included in the ball milling time.

5. The wear-resistant lubricating oil according to claim 2, characterized in that: In step S2, the method for mixing the pretreated wollastonite with the anhydrous ethanol solution of 3-aminopropyltriethoxysilane is as follows: the pretreated wollastonite is added to a ball mill, and the anhydrous ethanol solution of 3-aminopropyltriethoxysilane is added dropwise into the ball mill using a rubber-tipped dropper, and the ball milling reaction is carried out at a ball mill speed of 300 r / min for 30 hours.

6. The wear-resistant lubricating oil according to claim 5, characterized in that: During the 30-hour ball milling process, the direction of rotation was changed every 3 hours and the rotation was stopped for 30 minutes. This interval was not included in the ball milling time.

7. The wear-resistant lubricating oil according to claim 2, characterized in that: The specific operation steps of step S3 are: S31: dissolving gypsum powder in glycerol to form a mixed oil solution, placing the mixed oil solution in a water bath and heating it to 60° C., then keeping the temperature, adding modified wollastonite and stirring it magnetically for 1 hour to obtain solution A; S32: transferring solution A to an ultrasonic agitator, placing a UV lamp above the ultrasonic agitator, and reacting under ultrasonic stirring for 4-5 hours under UV irradiation to obtain solution B; S33: After vacuum filtering and drying Solution B for 24 hours, grind and sieve to obtain a wear-resistant additive.

8. The wear-resistant lubricating oil according to claim 7, characterized in that: In step S2, the UV wavelength used is 365 nm.

9. The wear-resistant lubricating oil according to claim 1, characterized in that: The base oil is a mineral base oil or a synthetic base oil.

10. A method for preparing the wear-resistant lubricating oil according to any one of claims 1 to 9, characterized in that: The preparation is carried out according to the following steps: a lubricating additive is added to the base oil, firstly magnetically stirred at 40° C. for 2 hours, and then ultrasonically dispersed using an ultrasonic cleaner for 1 hour to obtain the wear-resistant lubricating oil.

Images