A self-lubricating composite material for molded self-lubricating spherical bearings and its preparation method

Abstract

This invention discloses a self-lubricating composite material for molded self-lubricating spherical plain bearings and its preparation method. The self-lubricating composite material is composed of a composite filler, styrene, cobalt naphthenate, vinyl ester resin, and methyl ethyl ketone peroxide. The composite filler consists of polytetrafluoroethylene-coated titanium diboride filler, barium sulfate powder, and fumed silica powder in a mass ratio of 1:0.5-1:0.02-0.1. The mass ratio of vinyl ester resin, styrene, cobalt naphthenate, and composite filler is 1:0.3-0.5:0.002-0.004:0.2-0.4. The self-lubricating composite material provided by this invention combines the corrosion resistance and high strength of vinyl ester resin, the lubricity of polytetrafluoroethylene, the wear resistance of titanium diboride, the high specific gravity of barium sulfate, and the structural uniformity reinforced by fumed silica. Through the synergistic effect of the multi-component filler, the hardness, compressive strength, and tribological properties of the self-lubricating composite coating are effectively improved, enhancing its performance stability in self-lubricating spherical plain bearings, which is of great significance for the development of aerospace and other fields.

Description

Technical Field

[0001] This invention belongs to the field of lubrication materials technology, specifically relating to a self-lubricating composite material for molded self-lubricating spherical bearings and its preparation method. Background Technology

[0002] Self-lubricating spherical plain bearings possess advantages such as wear resistance, impact resistance, and excellent lubrication, and are used in heavy machinery, aerospace, and military equipment. Research on self-lubricating materials plays a crucial role in the study of self-lubricating spherical plain bearings, as their performance directly determines the bearing's performance and lifespan. Based on different lubricating materials, there are currently three types of self-lubricating spherical plain bearings on the market: inlaid, fabric, and molded. Molded self-lubricating spherical plain bearings are a current research hotspot in the high-end bearing field due to their seamless construction and ability to be machined to any thickness, resulting in more stable performance, continuous friction, and better environmental adaptability. However, high-end molded self-lubricating bearings currently rely on imports, and domestic research in this area is still in its early stages. The self-lubricating material for these bearings is formed by mixing and curing solid lubricant powder with binders such as resin and asphalt, combining the advantages of both filler and binder materials. Epoxy resins have become a focus of research in self-lubricating composite materials due to their advantages such as low molding shrinkage, good processability, excellent adhesion, mechanical properties, and reasonable cost. Numerous researchers have conducted extensive studies on epoxy resin-based composites. However, the high crosslinking density of the epoxy resin matrix, the brittleness of the cured system, poor toughness, poor impact resistance, and excessively high viscosity making it difficult to handle at room temperature have limited its development in the self-lubricating spherical bearing industry. Therefore, seeking a moldable self-lubricating composite material for spherical bearings with high load-bearing capacity and excellent tribological properties is extremely important. Summary of the Invention

[0003] To address the aforementioned problems, the first objective of this invention is to provide a self-lubricating composite material for self-lubricating spherical bearings, and the second objective of this invention is to provide a method for preparing the self-lubricating composite material and its application.

[0004] The objective of this invention is achieved by providing a self-lubricating composite material for molded self-lubricating spherical bearings, comprising composite filler, styrene, cobalt naphthenate, vinyl resin, and methyl ethyl ketone peroxide;

[0005] The composite filler is composed of polytetrafluoroethylene-coated titanium diboride filler, barium sulfate powder, and fumed silica powder in a mass ratio of 1:0.5-1:0.02-0.1.

[0006] The mass ratio of vinyl resin, styrene, cobalt naphthenate, and composite filler is 1:0.3-0.5:0.002-0.004:0.2-0.4;

[0007] The mass ratio of methyl ethyl ketone peroxide to vinyl resin is 1:50.

[0008] The beneficial effects of this invention are as follows: Firstly, this invention combines titanium diboride and polytetrafluoroethylene (PTFE) with polydopamine to form a core-shell structure of "soft lubricant coated with hard reinforcing agent." Compared to traditional soft PTFE fillers, the presence of hard titanium diboride acts as a supporting skeleton, which is beneficial for stress absorption and dispersion, and enhances the compressive properties, hardness, and wear resistance of the self-lubricating composite material of this invention. Secondly, by ball milling barium sulfate, fumed silica, and PTFE-coated titanium diboride filler to form a composite filler, the presence of surface-active groups in the fumed silica allows for thorough composite bonding between various fillers, improving the dispersibility and binding of the fillers in the polymer composite material, as well as the crosslinking degree of the self-lubricating composite material; the presence of barium sulfate increases the specific gravity of the self-lubricating composite material. Epoxy resin is a key focus of research on self-lubricating composite materials, but its poor fatigue resistance, crack resistance, and difficulty in handling limit its development in the field of self-lubricating bearings. Vinyl resin, on the other hand, combines the advantages of epoxy resin and polyester resin and can be considered a major development target for thermosetting resins. Therefore, the self-lubricating composite material provided by this invention combines the corrosion resistance and high strength of vinyl ester resin, the lubricity of polytetrafluoroethylene, the wear resistance of titanium diboride, the high specific gravity of barium sulfate, and the structural uniformity reinforced by fumed silica. Through the synergistic effect of multi-component fillers, the hardness, compressive strength, and tribological properties of the self-lubricating composite coating are effectively improved, enhancing its performance stability in self-lubricating spherical bearings. This is of great significance for the development of aerospace and other fields. Attached Figure Description

[0009] Figure 1 The image shows the polytetrafluoroethylene-coated titanium diboride filler prepared in Example 1, where a and c represent titanium diboride powder, modified titanium diboride, and polytetrafluoroethylene-coated titanium diboride filler, respectively.

[0010] Figure 2 This is a graph showing the trend of friction coefficient of the self-lubricating composite coating over time in Example 2;

[0011] Figure 3 This is a scanning electron microscope image of the wear surface of the self-lubricating composite coating in Example 2;

[0012] Figure 4 This is an EDS elemental distribution diagram of the self-lubricating composite coating in Example 2;

[0013] Figure 5 This is a light mirror image of the friction contact area between the self-lubricating composite coating and the small balls in the grinding pair in Example 2;

[0014] Figure 6The image shows the three-dimensional white light morphology (left) and wear track curve (right) of the self-lubricating composite coating in Example 2.

[0015] Figure 7 This is a scanning electron microscope image of the fracture surface of the self-lubricating composite coating in Example 2;

[0016] Figure 8 The graph shows the relationship between the friction coefficient and time for the self-lubricating composite coating prepared in Comparative Example 1.

[0017] Figure 9 The image shows the wear marks of the self-lubricating composite coating before and after the friction test in Comparative Example 1.

[0018] Figure 10 The image shows scanning electron microscope (SEM) images of the fracture surfaces of the self-lubricating composite coating before and after the friction test in Comparative Example 1.

[0019] Figure 11 The three-dimensional white light morphology (left) and wear track (right) of the self-lubricating composite coating before and after the friction test are shown in Comparative Example 1.

[0020] Figure 12 Here is a scanning electron microscope image of the wear marks on the self-lubricating composite coating of Comparative Example 2;

[0021] Figure 13 The graph shows the trend of friction coefficient of the self-lubricating composite coating over time in Comparative Example 2.

[0022] Figure 14 This is a light mirror image of the contact area between the steel balls of the grinding pair and the self-lubricating composite coating in Comparative Example 2.

[0023] Figure 15 The image shows a scanning electron microscope (SEM) image of the wear surface of the self-lubricating composite coating in Comparative Example 3.

[0024] Figure 16 The image shows a scanning electron microscope (SEM) image of the fracture surface of the self-lubricating composite coating in Comparative Example 3.

[0025] Figure 17 The curve showing the change in the friction coefficient of the self-lubricating composite coating over time in Comparative Example 4;

[0026] Figure 18 EDS elemental distribution diagram of the composite filler prepared in Comparative Example 4;

[0027] Figure 19 EDS elemental distribution diagram of the composite filler prepared in Comparative Example 5;

[0028] Figure 20 EDS elemental distribution diagram of the composite filler prepared for Comparative Example 6. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0030] This invention relates to a self-lubricating composite material for molded self-lubricating spherical bearings, which is composed of composite filler, styrene, cobalt naphthenate, vinyl resin and methyl ethyl ketone peroxide;

[0031] The composite filler is composed of polytetrafluoroethylene-coated titanium diboride filler, barium sulfate powder, and fumed silica powder in a mass ratio of 1:0.5-1:0.02-0.1.

[0032] The mass ratio of vinyl resin, styrene, cobalt naphthenate, and composite filler is 1:0.3-0.5:0.002-0.004:0.2-0.4;

[0033] The mass ratio of methyl ethyl ketone peroxide to vinyl resin is 1:50.

[0034] The preparation method of the polytetrafluoroethylene-coated titanium diboride filler is as follows:

[0035] 1) Add titanium diboride powder to polydopamine solution and stir at a constant speed in a water bath at 40-80℃ for 12-48h. Wash with anhydrous ethanol by centrifugation until the supernatant becomes clear. Place the precipitate in a vacuum drying oven and dry at 40-80℃ for 24-48h to obtain modified titanium diboride.

[0036] 2) Add the modified titanium diboride to a polytetrafluoroethylene emulsion containing 60% solids, and stir for 12 hours in a water bath at 400-800 rpm / min at 30-60℃. After the reaction is completed, place it in a vacuum drying oven and dry at 90-150℃ for 24 hours. Then grind it thoroughly and filter it through a 10 μm sieve to obtain polytetrafluoroethylene-coated titanium diboride filler.

[0037] The mass-to-volume ratio of titanium diboride powder to polydopamine solution is 1-10:1000 g / mL.

[0038] The mass-to-volume ratio of modified titanium diboride to polytetrafluoroethylene emulsion is 1-5:100g / mL.

[0039] In step 1), the particle size of the titanium diboride powder is 4-8 μm.

[0040] In step 1), the dopamine concentration in the polydopamine solution is 0.4 g / L, and the pH is adjusted to about 8.5 by tris(hydroxymethyl)aminomethane hydrochloride.

[0041] The present invention also provides a method for preparing the self-lubricating composite material for the molded self-lubricating spherical bearing, which is carried out according to the following steps:

[0042] a. Polytetrafluoroethylene-coated titanium diboride filler, barium sulfate powder and fumed silica powder are mixed and then ball-milled in a high-energy planetary ball mill at a speed of 300-400 r / min for 10 h-24 h to obtain composite filler.

[0043] b. Mix vinyl resin, styrene, cobalt naphthenate and composite filler and stir at a rate of 500-1200 rpm / min for 2 hours to obtain a mixed solution;

[0044] c. Add methyl ethyl ketone peroxide to the mixed solution, stir at a rate of 500-1200 rpm / min for 10-20 min, and then sonicate for 5-10 min to obtain the target self-lubricating composite material.

[0045] The present invention further provides a self-lubricating composite coating based on the self-lubricating composite material for molded self-lubricating spherical bearings. The preparation method of the self-lubricating composite coating is to pour the self-lubricating composite material into a silicone mold, place it in a reaction vessel, and react it at high temperature and high pressure at 100-120℃ for 1-4 hours. Then, it is placed in a vacuum drying oven at 50-90℃ for 1-4 hours and finally placed at room temperature for 12-24 hours to demold and obtain the target self-lubricating composite coating.

[0046] The present invention further provides the application of the self-lubricating composite material for the molded self-lubricating spherical plain bearing in the preparation of the self-lubricating spherical plain bearing. The preparation method of the self-lubricating spherical plain bearing is to inject the self-lubricating composite material into the self-lubricating spherical plain bearing through an injection mold, place the self-lubricating spherical plain bearing in a special reaction vessel, fix the outer ring and continuously rotate the inner ring, and react at high temperature and high pressure at 100-120℃ for 1-4 hours, then place it in a vacuum drying oven at 50-90℃ for 1-4 hours, and then place it at room temperature for 12-24 hours to obtain the self-lubricating spherical plain bearing.

[0047] Example 1

[0048] Take 10g of titanium diboride powder and add it to 1000ml of polydopamine solution with pH=8.5 and dopamine concentration of 0.4g / L; transfer it to a three-necked flask and place it in a magnetically stirred water bath, stirring at 1000r / min at 60℃ for 48h; after the reaction, wash with anhydrous ethanol and centrifuge until the supernatant is clear, then place it in a vacuum drying oven at 60℃ for 48h to obtain modified titanium diboride; add 10g of modified titanium diboride to 200ml of 60% solids content polytetrafluoroethylene emulsion, and transfer it to a three-necked flask. The mixture was placed in a magnetically stirred water bath and stirred at 500 rpm for 12 hours at 40°C. After the reaction, it was dried at 120°C for 24 hours. The mixture was then thoroughly ground to obtain polytetrafluoroethylene-coated titanium diboride filler. Then, 3 g of polytetrafluoroethylene-coated titanium diboride filler, 3 g of barium sulfate powder, and 0.3 g of fumed silica powder were mixed and placed in a high-energy planetary ball mill. The mixture was ball-milled at 400 rpm for 24 hours to obtain the composite filler. 20 g of vinyl resin, 8 g of styrene, 0.08 g of cobalt naphthenate, and 6.3 g of the composite filler were mixed and stirred at 1000 rpm for 2 hours. Then, 0.4 g of methyl ethyl ketone peroxide was added, and the mixture was stirred for another 20 minutes. The mixture was then placed in an ultrasonic water bath and ultrasonically vibrated at 300 W for 10 minutes to obtain a self-lubricating composite material. The self-lubricating composite material was poured into a silicone mold, and the mold was placed in a reaction vessel and reacted at 120°C under high temperature and pressure for 2 hours. Then it was placed in a vacuum drying oven at 60°C for 2 hours and finally placed at room temperature for 24 hours before demolding to obtain the self-lubricating composite coating.

[0049] from Figure 1 It can be seen that the original titanium diboride was grayish-black, and after being coated with a layer of polydopamine, it turned reddish-brown. The pure white polytetrafluoroethylene coating on the outermost layer, when superimposed on the original reddish-brown, showed an earthy yellow color, indicating that the polytetrafluoroethylene-coated titanium diboride filler in this embodiment was successfully prepared.

[0050] Example 2

[0051] In this embodiment, the preparation process of polytetrafluoroethylene-coated titanium diboride filler is the same as in Example 1. Then, 4g of polytetrafluoroethylene-coated titanium diboride filler, 4g of barium sulfate powder, and 0.3g of fumed silica powder are mixed and placed in a high-energy planetary ball mill. The mixture is ball-milled at 800 r / min for 24 h to obtain the composite filler. 20g of vinyl resin, 8g of styrene, 0.08g of cobalt naphthenate, and 8.3g of the composite filler are mixed and stirred at 1000 r / min for 2 h. Then, 0.4g of methyl ethyl ketone peroxide is added, and stirring continues for 20 min. The mixture is then ultrasonically vibrated in an ultrasonic water bath for 10 min to obtain a self-lubricating composite material. The self-lubricating composite material is then poured into a silicone mold, and the mold is placed in a reaction vessel and reacted at 120°C under high temperature and pressure for 2 h. Afterward, it is dried in a vacuum drying oven at 60°C for 2 h, and then left at room temperature for 24 h before demolding to obtain the self-lubricating composite coating.

[0052] Example 3

[0053] In this embodiment, the preparation process of polytetrafluoroethylene-coated titanium diboride filler is the same as in Example 1. Then, 2g of polytetrafluoroethylene-coated titanium diboride filler, 5g of barium sulfate powder, and 0.5g of fumed silica powder are mixed and placed in a high-energy planetary ball mill. The mixture is ball-milled at 800 rpm for 12 hours to obtain the composite filler. 20g of vinyl resin, 10g of styrene, 0.08g of cobalt naphthenate, and 7.5g of the composite filler are mixed and stirred at 1000 rpm for 2 hours. Then, 0.4g of methyl ethyl ketone peroxide is added, and stirring continues for 20 minutes. The mixture is then placed in an ultrasonic water bath and ultrasonically vibrated at 300W for 10 minutes to obtain a self-lubricating composite material. The self-lubricating composite material is then poured into a silicone mold, and the mold is placed in a reaction vessel and reacted at 115°C under high temperature and pressure for 2 hours. It is then dried in a vacuum drying oven at 60°C for 2 hours, and finally placed at room temperature for 24 hours before demolding to obtain the self-lubricating composite coating.

[0054] Example 4

[0055] Take 10g of titanium diboride powder and add it to 1000ml of polydopamine solution with pH=8.5 and dopamine concentration of 0.4g / L; transfer it to a three-necked flask and place it in a magnetically stirred water bath, stirring at 70℃ and 800r / min for 48h; after the reaction, wash with anhydrous ethanol and centrifuge until the supernatant is clear, then place it in a vacuum drying oven at 50℃ for 48h to obtain modified titanium diboride; add 10g of modified titanium diboride to 200ml of 60% solids content polytetrafluoroethylene In a olefin emulsion, the mixture was transferred to a three-necked flask and placed in a magnetically stirred water bath. The mixture was stirred at 700 rpm for 12 hours at 60°C. After the reaction, it was dried at 100°C for 24 hours. The mixture was then thoroughly ground to obtain polytetrafluoroethylene-coated titanium diboride filler. Then, 3 g of polytetrafluoroethylene-coated titanium diboride filler, 3 g of barium sulfate powder, and 0.3 g of fumed silica powder were mixed and placed in a high-energy planetary ball mill. The mixture was ball-milled at 400 rpm for 24 hours to obtain a composite filler. 20 g of vinyl resin, 8 g of styrene, 0.08 g of cobalt naphthenate, and 6.3 g of the composite filler were mixed and stirred at 800 rpm for 2 hours. Then, 0.4 g of methyl ethyl ketone peroxide was added, and the mixture was stirred for another 20 minutes. Finally, the mixture was placed in an ultrasonic water bath and ultrasonically vibrated at 300 W for 5 minutes to obtain a self-lubricating composite material. The self-lubricating composite material was poured into a silicone mold, and the mold was placed in a reaction vessel and reacted at 110°C under high temperature and pressure for 1.5 hours. Then it was placed in a vacuum drying oven at 80°C for 1.5 hours and finally placed at room temperature for 24 hours to demold and obtain the self-lubricating composite coating.

[0056] Example 5

[0057] Take 10g of titanium diboride powder and add it to 1000ml of polydopamine solution with pH=8.5 and dopamine concentration of 0.4g / L. Transfer the solution to a three-necked flask and place it in a magnetically stirred water bath. Stir at 50℃ and 600r / min for 48h. After the reaction is complete, wash with anhydrous ethanol and centrifuge until the supernatant is clear. Place the supernatant in a vacuum drying oven at 70℃ for 24h to obtain modified titanium diboride. Add 5g of modified titanium diboride to 200ml of 60% solids polytetrafluoroethylene. The emulsion was transferred to a three-necked flask and placed in a magnetically stirred water bath. The mixture was stirred at 1000 rpm for 16 hours at 50°C. After the reaction, it was dried at 80°C for 24 hours. The material was then thoroughly ground to obtain polytetrafluoroethylene-coated titanium diboride filler. Then, 3 g of polytetrafluoroethylene-coated titanium diboride filler, 3 g of barium sulfate powder, and 0.3 g of fumed silica powder were mixed and placed in a high-energy planetary ball mill. The mixture was ball-milled at 400 rpm for 24 hours to obtain the composite filler. 20 g of vinyl resin, 8 g of styrene, 0.08 g of cobalt naphthenate, and 6.3 g of the composite filler were mixed and stirred at 1000 rpm for 2 hours. Then, 0.4 g of methyl ethyl ketone peroxide was added, and stirring continued for 20 minutes. The mixture was then placed in an ultrasonic water bath and ultrasonically vibrated at 300 W for 10 minutes to obtain a self-lubricating composite material. The self-lubricating composite material was poured into a silicone mold, and the mold was placed in a reaction vessel and reacted at 100°C under high temperature and pressure for 4 hours. Then it was placed in a vacuum drying oven at 90°C for 1 hour, and finally placed at room temperature for 48 hours to demold and obtain the self-lubricating composite coating.

[0058] Comparative Example 1

[0059] The difference between Comparative Example 1 and Example 2 is that in Comparative Example 1, the polytetrafluoroethylene-coated titanium diboride filler was replaced by 3g of conventional polytetrafluoroethylene powder, while other conditions remained unchanged.

[0060] Comparative Example 2

[0061] The difference between Comparative Example 2 and Example 2 is that in Comparative Example 2, the polytetrafluoroethylene-coated titanium diboride filler was replaced by 3g of titanium diboride powder, while other conditions remained unchanged.

[0062] Comparative Example 3

[0063] The difference between Comparative Example 3 and Example 2 is that in Comparative Example 3, the polytetrafluoroethylene-coated titanium diboride filler was replaced by a mixture of 1g titanium diboride and 2g polytetrafluoroethylene emulsion, while other conditions remained unchanged.

[0064] Comparative Example 4

[0065] The difference between Comparative Example 4 and Example 2 is that in Comparative Example 4, mechanical mixing was used instead of ball milling to prepare the composite filler.

[0066] The composite filler prepared in Comparative Example 4 was not ball-milled, resulting in uneven filler distribution and agglomeration. Figure 18 ).

[0067] Comparative Example 5

[0068] The difference between Comparative Example 5 and Example 2 is that barium sulfate powder was not added to the composite filler in Comparative Example 5.

[0069] from Figure 19 It can be seen that the polytetrafluoroethylene in the composite filler prepared in this comparative example agglomerates and is not evenly dispersed, resulting in poor performance.

[0070] Comparative Example 6

[0071] The difference between Comparative Example 6 and Example 2 is that no fumed silica powder was added to the composite filler in Comparative Example 6.

[0072] Comparative Example 7

[0073] The difference between Comparative Example 7 and Example 2 is that in Comparative Example 7, the mold was not placed in the reactor for high temperature and high pressure reaction, but was directly placed in the drying oven for curing of the composite material at 120°C.

[0074] Comparative Example 8

[0075] The difference between Comparative Example 8 and Example 2 is that in Comparative Example 8, the vinyl resin was replaced with epoxy resin, while other conditions remained unchanged.

[0076] Detection example

[0077] The self-lubricating composite layers prepared in Examples 1-3 and Comparative Examples 1-7 were cured using the same mold, and friction, hardness and compression performance tests were conducted using the same test parameters.

[0078] The compression performance test was conducted according to GB / T 2569-1995. The composite material specimens were tested at room temperature and a running speed of 5 mm / min. Four tests were performed for each group, and the average value was taken.

[0079] The hardness test was conducted using a Shore D hardness tester. During the test, the sample was first placed on a horizontal platform, the hardness tester was held in a vertical position, and the indenter was pressed down to penetrate the sample surface. The instrument displayed the corresponding hardness value. Five points were taken for each group and the average value was taken.

[0080] Friction and wear tests were conducted using a ball-and-disc friction and wear tester, performing rotational sliding friction tests on the composite material. The tests were performed at online speeds of 0.1 ms. -1The tests were conducted at a sliding speed and a load of 1000N, with each test lasting 60 minutes at room temperature. Before each test, the surfaces were polished with 1500-grit sandpaper of the same specification to ensure consistent surface roughness. The grinding pair consisted of 6mm diameter balls (440C stainless steel, G10 grade). All samples were cleaned with anhydrous ethanol before and after the tests.

[0081] The friction coefficient of the test results is taken as the average value over 60 minutes, and the wear rate is calculated using the following formula:

[0082]

[0083] Where Δm is the mass loss (g), L is the sliding distance (m), and ρ is the density of the composite material (g / cm³). 3 ),F N It is the normal load (N).

[0084] The results are shown in Table 1 and... Figure 2-17 As shown.

[0085] Table 1. Performance parameters of the composite materials obtained in Examples 1-3 and Comparative Examples 1-8

[0086] Example 1 0.1118 <![CDATA[39.1553×10 -14 m 3 (Nm) -1 ]]> 82HD 171MPa Example 2 0.0758 <![CDATA[26.7116×10 -14 m 3 (Nm) -1 ]]> 84HD 186MPa Example 3 0.1026 <![CDATA[29.4136×10 -14 m 3 (Nm) -1 ]]> 82HD 173MPa Comparative Example 1 0.148 <![CDATA[92.8162×10 -14 m 3 (Nm) -1 ]]> 70.5HD 80MPa Comparative Example 2 0.1784 <![CDATA[84.9463×10 -14 m 3 (Nm) -1 ]]> 72HD 109MPa Comparative Example 3 0.1365 <![CDATA[82.4517×10 -14 m 3 (Nm) -1 ]]> 73HD 76MPa Comparative Example 4 0.1256 <![CDATA[76.1337×10 -14 m 3 (Nm) -1 ]]> 68HD 60MPa Comparative Example 5 0.1406 <![CDATA[69.0539×10 -14 m 3 (Nm) -1 ]]> 67HD 63MPa Comparative Example 6 0.1543 <![CDATA[66.6619×10 -14 m 3 (Nm) -1 ]]> 70.5HD 67MPa Comparative Example 7 0.1486 <![CDATA[73.4535×10 -14 m 3 (Nm) -1 ]]> 67HD 43MPa

[0087] Results analysis: As shown in Table 1, the self-lubricating coatings prepared in Examples 1-3 have significantly better frictional properties, hardness and compressive strength than those in Comparative Examples 1-7.

[0088] In the friction performance test, the self-lubricating composite coating prepared in Example 2 maintained a very low coefficient of friction after the friction reached stability, and the curve was smooth without fluctuation, with an average coefficient of friction of 0.0758. Figure 2 Its wear surface is smooth and continuous. Figure 3 Only a few microcracks are present, indicating slight fatigue wear. The surface of the grinding balls is smooth, with only a few scratches. Figure 5 This demonstrates the excellent tribological properties of the composite material. From... Figure 4 It can be seen that the filler elements in the self-lubricating composite coating are uniformly distributed and no agglomeration occurs, demonstrating the uniformity of the self-lubricating composite coating prepared in Example 2. From Figure 6 It can be seen that the worn surface is clear, smooth and continuous, and the wear marks are relatively narrow and shallow, indicating the excellent wear resistance of the self-lubricating composite coating prepared in Example 2. From... Figure 7 It can be seen that the fracture surface is generally free of fragments, with only a small amount of agglomerates and tail-like cracks acting as pinning agents to limit crack propagation, which is the reason for its excellent compressive properties.

[0089] from Figure 8It can be seen that the friction curve of the self-lubricating composite coating prepared in Comparative Example 1 fluctuates significantly and shows an upward trend, with an average friction coefficient of approximately 0.148, which is much larger than the average friction coefficient of Example 2, indicating that its friction-reducing effect is poor. Figure 9 It can be seen that the surface of the wear marks is rough, with numerous cracks and grooves, indicating poor wear resistance. From Figure 10 It can be seen that the fracture surface contains many small particles, and the fracture surface is rough and irregular, indicating poor compressive properties. From Figure 11 It can be seen that, compared with Example 2, the wear surface of Comparative Example 1 is rough, and the wear marks are wider and deeper, indicating that its wear resistance is poor.

[0090] from Figure 12 It can be seen that the self-lubricating coating prepared in Comparative Example 2 has rough wear marks, contains fragments, and has a large number of pores inside, leading to a decrease in performance. From Figure 13 It can be seen that its coefficient of friction is relatively large, fluctuates significantly, and continues to rise, with the maximum coefficient of friction reaching 0.19, indicating that the self-lubricating coating has not played a role in reducing friction. Furthermore, from... Figure 14 It can be seen that the wear marks on the grinding pair are messy and numerous, indicating that the grinding pair is severely worn.

[0091] Because there is no polydopamine as a "connecting bridge," polytetrafluoroethylene cannot be laminated onto the titanium diboride surface. The self-lubricating coating prepared in Comparative Example 3 exhibits poor compressive properties and hardness. The wear surface is rough, with numerous bulges and cracks, indicating poor tribological properties. Figure 15 Its fracture surface is rough and disordered, containing a large amount of particulate matter. Figure 16 This indicates that its compression performance is poor.

[0092] Figure 17 The results show that the friction curve of the self-lubricating coating prepared in Comparative Example 4 fluctuates significantly, and the friction coefficient remains high, indicating poor friction reduction effect.

[0093] The composite filler prepared in Comparative Example 6 lacked the active groups of fumed silica as an intermediary, resulting in barium sulfate and modified filler B failing to combine and exhibiting agglomeration and uneven dispersion. Figure 20 This results in poor performance. Table 1 shows that it has a high wear rate and low hardness and compressive strength.

[0094] The composite filler prepared in Comparative Example 7 had a loose surface with numerous voids. This was because the air bubbles could not be expelled before solidification, resulting in structural defects and extremely poor performance. In Comparative Example 8, the high viscosity of the epoxy resin made the preparation process extremely inconvenient, leading to a self-lubricating coating with poor compressive properties and exhibiting brittle fracture characteristics.

Claims

1. A self-lubricating composite material for molded self-lubricating spherical bearings, characterized in that, It is composed of composite filler, styrene, cobalt naphthenate, vinyl resin and methyl ethyl ketone peroxide; The composite filler is composed of polytetrafluoroethylene-coated titanium diboride filler, barium sulfate powder, and fumed silica powder in a mass ratio of 1:0.5~1:0.02~0.

1. The mass ratio of vinyl resin, styrene, cobalt naphthenate, and composite filler is 1:0.3~0.5:0.002~0.004:0.2~0.4; The mass ratio of methyl ethyl ketone peroxide to vinyl resin is 1:50; The preparation method of the polytetrafluoroethylene-coated titanium diboride filler is as follows: 1) Add titanium diboride powder to polydopamine solution and stir at a constant speed in a water bath at 40~80℃ for 12h~48h. Wash with anhydrous ethanol by centrifugation until the supernatant becomes clear. Place the precipitate in a vacuum drying oven and dry at 40~80℃ for 24h~48h to obtain modified titanium diboride. 2) Add the modified titanium diboride to a polytetrafluoroethylene emulsion containing 60% solids, and stir for 12 hours at 400-800 rpm in a water bath at 30-60℃. After the reaction is completed, place it in a vacuum drying oven and dry at 90-150℃ for 24 hours. Then grind it thoroughly and filter it through a 10μm sieve to obtain polytetrafluoroethylene-coated titanium diboride filler. The mass-to-volume ratio of titanium diboride powder to polydopamine solution is 1~10:1000g / mL; The mass-to-volume ratio of modified titanium diboride to polytetrafluoroethylene emulsion is 1~5:100g / mL.

2. The self-lubricating composite material for molded self-lubricating spherical bearings according to claim 1, characterized in that, In step 1), the particle size of the titanium diboride powder is 4~8μm.

3. The self-lubricating composite material for molded self-lubricating spherical bearings according to claim 1, characterized in that, In step 1), the dopamine concentration in the polydopamine solution is 0.4 g / L, and the pH is adjusted to 8.5 by tris(hydroxymethyl)aminomethane hydrochloride.

4. The method for preparing the self-lubricating composite material for molded self-lubricating spherical bearings according to claim 1, characterized in that, Follow these steps to achieve the following: a. A composite filler is obtained by mixing polytetrafluoroethylene-coated titanium diboride filler, barium sulfate powder and fumed silica powder, and then ball milling them in a high-energy planetary ball mill at a speed of 300-400 rpm for 10-24 hours. b. Mix vinyl resin, styrene, cobalt naphthenate and composite filler and stir at a speed of 500~1200 rpm for 2 hours to obtain a mixed solution; c. Add methyl ethyl ketone peroxide to the mixed solution, stir at a rate of 500~1200 rpm for 10~20 min, and then sonicate for 5~10 min to obtain the target self-lubricating composite material.

5. A self-lubricating composite coating based on the self-lubricating composite material for molded self-lubricating spherical bearings according to claim 1, characterized in that, The method for preparing the self-lubricating composite coating is to pour the self-lubricating composite material into a silicone mold, place it in a reaction vessel, and react it at a high temperature and high pressure of 100~120℃ for 1~4 hours. Then, it is placed in a vacuum drying oven at 50~90℃ for 1~4 hours and finally placed at room temperature for 12~24 hours to demold and obtain the target self-lubricating composite coating.

6. The application of the self-lubricating composite material for molded self-lubricating spherical plain bearings according to claim 1 in the preparation of self-lubricating spherical plain bearings, characterized in that, The method for preparing the self-lubricating spherical bearing is to inject the self-lubricating composite material into the self-lubricating spherical bearing through an injection mold, place the self-lubricating spherical bearing in a reaction vessel, fix the outer ring and continuously rotate the inner ring, and react at high temperature and high pressure at 100~120℃ for 1~4 hours, then place it in a vacuum drying oven at 50~90℃ for 1~4 hours, and then place it at room temperature for 12~24 hours to obtain the self-lubricating spherical bearing.

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