Self-lubricating composite material, preparation method thereof and water-lubricated bearing

Abstract

The invention relates to a self-lubricating composite material, a preparation method thereof and a water-lubricated bearing, the self-lubricating composite material comprises a base material and microcapsules dispersed in the base material, the base material comprises a first polymer, the microcapsules comprise a first microcapsule and a second microcapsule, and the first polymer comprises a first polymer and a second polymer. The first microcapsule comprises a first core material and a first wall material coating the first core material, the first core material comprises calcium salt, the second microcapsule comprises a second core material and a second wall material coating the second core material, and the second core material comprises one or more of sodium alginate and polyvinyl alcohol, so that the friction loss of the water-lubricated bearing can be reduced, and the service life of the water-lubricated bearing can be prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of tribology, and in particular to a self-lubricating composite material and a preparation method thereof, and a water-lubricated bearing. Background Art

[0002] As economic demand for transportation grows, the number of ships sailing on oceans and rivers continues to climb. Pollution from ship operations poses a serious threat to marine ecosystems and has attracted widespread attention. As a crucial component of ship propulsion systems, water-lubricated bearings utilize water as a lubricant to protect and lubricate friction surfaces, effectively resolving the issue of oil-based lubricant leakage caused by seal failure in traditional oil-lubricated bearings. Water-lubricated bearings are key components of ship transmission systems. Operating at low speeds and heavy loads, they struggle to form hydrodynamic lubrication, leading to severe wear and prone to failure. This has become a prominent issue affecting the normal operation of ships. Summary of the Invention

[0003] The present application provides a self-lubricating composite material, a preparation method thereof, and a water-lubricated bearing, aiming to reduce the friction loss of the water-lubricated bearing and extend its service life.

[0004] In a first aspect of the present application, a self-lubricating composite material is provided, comprising a matrix material and microcapsules dispersed in the matrix material, wherein the matrix material comprises a first polymer, the microcapsules comprise first microcapsules and second microcapsules, the first microcapsules comprise a first core material and a first wall material coating the first core material, the first core material comprises a calcium salt, the second microcapsules comprise a second core material and a second wall material coating the second core material, and the second core material comprises one or more of sodium alginate and polyvinyl alcohol.

[0005] In some embodiments, the mass ratio of the calcium salt to at least one of the sodium alginate and the polyvinyl alcohol is 1:2 to 1:1.

[0006] In some embodiments, the calcium salt includes one or more of calcium carbonate, calcium chloride, and calcium lactate.

[0007] In some embodiments, the mass ratio of the microcapsules to the matrix material is (3-10):100.

[0008] In some embodiments, the mass proportion of the calcium salt in the first microcapsule is 15% to 50%.

[0009] In some embodiments, the mass proportion of at least one of the sodium alginate and the polyvinyl alcohol in the second microcapsule is 33% to 50%.

[0010] In some embodiments, the first polymer includes one or more of polyetheretherketone, polyurethane, ultra-high molecular weight polyethylene, nylon, and polytetrafluoroethylene, and the molecular weight of the ultra-high molecular weight polyethylene is 1.5 million Daltons to 8 million Daltons.

[0011] In some embodiments, the first core material and the second core material each independently include a second polymer including one or more of polysulfone and polymethyl methacrylate.

[0012] In a second aspect of the present application, a method for preparing a self-lubricating composite material is provided, comprising the following steps:

[0013] Mixing a matrix material with microcapsules to obtain a mixture; the matrix material includes a first polymer, the microcapsules include first microcapsules and second microcapsules, the first microcapsules include a first core material and a first wall material covering the first core material, the first core material includes a calcium salt, the second microcapsules include a second core material and a second wall material covering the second core material, the second core material includes one or more of sodium alginate and polyvinyl alcohol;

[0014] The mixed material is subjected to vacuum sintering treatment to obtain the self-lubricating composite material.

[0015] In some embodiments, the step of vacuum sintering the mixture includes: applying a pressure of 1MPa~10MPa to the mixture to remove air in the mixture, then keeping the mixture at 140℃~330℃ for 20min~60min, and then keeping the mixture at 120℃~250℃ for 10min~30min.

[0016] In some embodiments, the mass ratio of the calcium salt to at least one of the sodium alginate and the polyvinyl alcohol is 1:2 to 1:1.

[0017] In some embodiments, the calcium salt includes one or more of calcium carbonate, calcium chloride, and calcium lactate.

[0018] In some embodiments, the mass ratio of the microcapsules to the matrix material is (3-10):100.

[0019] The third aspect of the present application provides a water-lubricated bearing, comprising at least one of the self-lubricating composite material described in the first aspect of the present application and the self-lubricating composite material prepared by the preparation method described in the second aspect of the present application.

[0020] Compared with traditional technologies, the above self-lubricating composite materials have at least the following advantages:

[0021] In the self-lubricating composite material described above, a calcium salt capable of rapidly gelling is compounded with at least one of sodium alginate and polyvinyl alcohol in first and second microcapsules, respectively. The first and second microcapsules are then dispersed in a matrix material comprising a first polymer. As friction and wear progress, the first and second microcapsules are worn away, releasing the first and second core materials. This allows the gel formed by the calcium salt and at least one of sodium alginate and polyvinyl alcohol to continuously form on the worn surface. Because the gel possesses both adhesive and lubricating properties, the worn surface can still maintain a layer of water molecules, significantly reducing the coefficient of friction, thereby significantly reducing frictional losses and extending the service life of the equipment. The application of self-lubricating composite materials in water-lubricated bearings can effectively address the wear, corrosion, noise, reliability, and life issues of ship shafting (such as thrust shafts, drive shafts, and stern shafts) in seawater environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a SEM (scanning electron microscope) image of the microcapsules prepared in Example 1 of the present application.

[0023] Figure 2 Schematic diagram of the mold, mixture and pressing head in the sintering process of Example 1 of the present application.

[0024] Figure 3 This is the sintering system for sintering the mixed material of Example 1 of the present application.

[0025] Figure 4 This is a diagram of the action mechanism of the first microcapsules and the second microcapsules in the self-lubricating composite material prepared in Example 1 of the present application.

[0026] Figure 5 This is a bar graph showing the variation of the friction coefficient with the rotation speed for Examples 1 to 4 and Comparative Example 1 of the present application.

[0027] Description of reference numerals:

[0028] 1. Mold; 2. Press head; 3. Mixture. DETAILED DESCRIPTION

[0029] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0030] In this application, terms such as "first aspect," "second aspect," and "third aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, terms such as "first," "second," and "third," etc., are intended only to provide a non-exhaustive enumeration and description and should not constitute a closed-ended limitation on quantity.

[0031] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0032] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0033] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0034] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more related listed items. The term "multiple" in this application means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0035] Commonly used materials for water-lubricated bearings include iron plowwood ceramics, rubber, polymers, etc. In recent decades, polymer materials have been widely used in the manufacture of water-lubricated tail pipe bearings due to their corrosion resistance and good chemical stability, but they also bring serious vibration and wear problems. Under low-speed and heavy-load conditions, the serious wear and noise problems of water-lubricated wearing parts are particularly troublesome. Although polymer materials are widely used in the preparation of water-lubricated bearings due to their good corrosion resistance, wear resistance and self-lubricating properties, in a water-lubricated environment, it is difficult to further improve the friction reduction and wear resistance of polymer materials due to the difficulty in adding lubricants. There is still the problem that it is difficult to form a stable water film at low speed, and high pressure may squeeze out the lubricating water film, leading to a boundary lubrication state.

[0036] Based on this, the first aspect of the present application provides a self-lubricating composite material, including a matrix material and microcapsules dispersed in the matrix material, the matrix material includes a first polymer, the microcapsules include first microcapsules and second microcapsules, the first microcapsules include a first core material and a first wall material coating the first core material, the first core material includes calcium salt, the second microcapsules include a second core material and a second wall material coating the second core material, and the second core material includes sodium alginate.

[0037] In the self-lubricating composite material described above, a calcium salt capable of rapidly gelling is compounded with at least one of sodium alginate and polyvinyl alcohol in first and second microcapsules, respectively. The first and second microcapsules are then dispersed in a matrix material comprising a first polymer. As friction and wear progress, the first and second microcapsules are worn away, releasing the first and second core materials. This allows the gel formed by the calcium salt and at least one of sodium alginate and polyvinyl alcohol to continuously form on the worn surface. Because the gel possesses both adhesive and lubricating properties, the worn surface can still maintain a layer of water molecules, significantly reducing the coefficient of friction, thereby significantly reducing frictional losses and extending the service life of the equipment. The application of self-lubricating composite materials in water-lubricated bearings can effectively address the wear, corrosion, noise, reliability, and life issues of ship shafting (such as thrust shafts, drive shafts, and stern shafts) in seawater environments.

[0038] Compared to traditional gel coating technology, the self-lubricating composite material described in this application combines a matrix material, a first microcapsule, and a second microcapsule. The matrix material provides rigid support, while the first and second microcapsules provide lubrication. During the friction process, gel is continuously generated, achieving sustainable lubrication. Furthermore, the first and second microcapsules are uniformly dispersed in the matrix material, enabling orderly and uniform release during friction. Furthermore, the self-lubricating composite material described in this application encapsulates the two materials that make up the gel (calcium salt and sodium alginate) within the first and second microcapsules, respectively, rather than directly incorporating the calcium salt and sodium alginate into the matrix material or into the same microcapsule. This effectively prevents gel failure during hot pressing or damage to the mechanical properties of the matrix material due to swelling of the gel within the matrix material.

[0039] In some embodiments, the mass ratio of the calcium salt to at least one of sodium alginate and polyvinyl alcohol is 1:2 to 1:1. That is, the mass ratio of at least one of sodium alginate and polyvinyl alcohol to the calcium salt is 1:1 to 2:1. Regulating the mass ratio of the calcium salt to at least one of sodium alginate and polyvinyl alcohol within the above range is beneficial to further reduce the friction coefficient. As a non-limiting example, the mass ratio of the calcium salt to at least one of sodium alginate and polyvinyl alcohol includes, but is not limited to, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, or a range between any two of the foregoing.

[0040] In some embodiments, the calcium salt includes one or more of calcium carbonate, calcium chloride, and calcium lactate.

[0041] In some embodiments, the mass ratio of microcapsules to matrix material is (3-10):100. This helps further reduce the friction coefficient. As non-limiting examples, the mass ratio of microcapsules to matrix material includes, but is not limited to, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, or a range between any two of the foregoing.

[0042] In some embodiments, the mass percentage of the calcium salt in the first microcapsule is 15% to 50%. As non-limiting examples, the mass percentage of the calcium salt in the first microcapsule includes, but is not limited to, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any range therebetween.

[0043] In some embodiments, the mass percentage of at least one of sodium alginate and polyvinyl alcohol in the second microcapsule is 33% to 50%. That is, the mass percentage of at least one of sodium alginate and polyvinyl alcohol in the second microcapsule is 33% to 50%. As non-limiting examples, the mass percentage of at least one of sodium alginate and polyvinyl alcohol in the second microcapsule includes, but is not limited to, 33%, 35%, 37%, 40%, 42%, 45%, 47%, 50%, or any range therebetween.

[0044] Regulating the mass proportion of calcium salt in the first microcapsule or regulating the mass proportion of at least one of sodium alginate and polyvinyl alcohol in the second microcapsule within the above range is beneficial to coating the calcium salt or coating at least one of sodium alginate and polyvinyl alcohol.

[0045] In some embodiments, the first polymer comprises one or more of polyetheretherketone, polyurethane, ultra-high molecular weight polyethylene, nylon, and polytetrafluoroethylene. In some embodiments, the ultra-high molecular weight polyethylene has a molecular weight of 1.5 million Daltons to 8 million Daltons.

[0046] In some embodiments, the first core material and the second core material each independently include a second polymer including one or more of polysulfone and polymethyl methacrylate.

[0047] In some embodiments, the average particle size of the microcapsules is 1 μm to 10 μm. As non-limiting examples, the average particle size of the microcapsules includes, but is not limited to, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a range between any two of the foregoing.

[0048] In a second aspect of the present application, a method for preparing a self-lubricating composite material is provided, comprising the following steps:

[0049] Mixing a matrix material with microcapsules to obtain a mixture; the matrix material includes a first polymer, the microcapsules include first microcapsules and second microcapsules, the first microcapsules include a first core material and a first wall material covering the first core material, the first core material includes a calcium salt, the second microcapsules include a second core material and a second wall material covering the second core material, and the second core material includes one or more of sodium alginate and polyvinyl alcohol;

[0050] The mixed material is subjected to vacuum sintering treatment to obtain a self-lubricating composite material.

[0051] The calcium salt capable of quickly generating a gel is compounded with at least one of sodium alginate and polyvinyl alcohol in the first microcapsule and the second microcapsule respectively, and then the first microcapsule and the second microcapsule are dispersed in the matrix material including the first polymer. With the progress of friction and wear, the first microcapsule and the second microcapsule are broken to release the first core material and the second core material, so that the gel is continuously generated on the worn surface. Since the gel has adhesion and lubricity, the water molecule layer can be maintained on the worn surface under low-speed heavy-load working conditions, the friction coefficient is significantly reduced, the friction loss is greatly reduced, and the service life of the equipment is prolonged. The self-lubricating composite material is applied to a water-lubricated bearing, which can effectively solve the problems of wear, corrosion, noise, reliability and service life of a ship shaft system (such as a thrust shaft, a transmission shaft and a stern shaft) in a seawater environment.

[0052] In some embodiments, the step of vacuum sintering the mixture includes: applying a pressure of 1 MPa to 10 MPa to the mixture to remove air in the mixture, and then heat preserving at 140°C to 330°C for 20 minutes to 60 minutes, and then heat preserving at 120°C to 250°C for 10 minutes to 30 minutes. Removing air in the mixture is to make the mixture in a vacuum environment, and the pressure applied to the mixture and the vacuum sintering treatment are beneficial to improve the density and bonding strength of the mixture, thereby improving the forming quality of the mixture. Taking polyether ether ketone as the first polymer, for example, polyether ether ketone has a high crystallization rate at 250°C, and the heat preserving process can improve the crystallinity of polyether ether ketone, thereby improving the mechanical properties and wear resistance of polyether ether ketone.

[0053] In some embodiments, the mass ratio of the calcium salt to at least one of sodium alginate and polyvinyl alcohol is 1:2 to 1:1.

[0054] In some embodiments, the calcium salt includes one or more of calcium carbonate, calcium chloride and calcium lactate.

[0055] In some embodiments, the mass ratio of the microcapsule to the matrix material is (3 to 10):100.

[0056] In some embodiments, the mass percentage of the calcium salt in the first microcapsule is 15% to 50%.

[0057] In some embodiments, the mass percentage of at least one of sodium alginate and polyvinyl alcohol in the second microcapsule is 33% to 50%.

[0058] It should be noted that the self-lubricating composite material described above can be obtained by adjusting the process conditions of the preparation method of the self-lubricating composite material described above.

[0059] The third aspect of the present application provides a water-lubricated bearing, comprising at least one of the self-lubricating composite material described in the first aspect of the present application and the self-lubricating composite material prepared by the preparation method described in the second aspect of the present application.

[0060] To further illustrate the present application, the technical solutions of the present application are described in detail below with reference to specific examples. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in the art or in accordance with the product instructions were used. Reagents or instruments used, for which the manufacturer is not specified, are all commercially available conventional products.

[0061] Example 1

[0062] The preparation method of the self-lubricating composite material comprises the following steps:

[0063] (1) Preparation of microcapsules

[0064] (1.1) Component A was prepared by dissolving 3 g of calcium carbonate in 100 mL of deionized water. 10 g of component A was mixed with 1 g of emulsifier Span 80, and the mixture was subjected to cell pulverization for 10 minutes. The mixture was then mixed with 100 mL of dichloromethane containing 3 g of polysulfone to obtain a mixture A.

[0065] (1.2) Dissolve 3 g of sodium alginate in 100 mL of deionized water to prepare component B. Mix 10 g of component B with 100 mL of dichloromethane containing 3 g of polysulfone and add 1 g of Span 80. Then, pulverize the cells for 10 minutes to obtain a mixture B. The mass ratio of calcium carbonate to sodium alginate is 1:1.

[0066] (1.3) Prepare a 1 wt% polyvinyl alcohol aqueous solution as a dispersion. Add Mixture A and Mixture B to the dispersion at 42°C and a stirring rate of 300 r / min. Continue heating and stirring for 4 hours. Use a solvent evaporation method to evaporate the dichloromethane during the heating and stirring process, and the polysulfone wall material condenses to form an outer shell, thereby producing microcapsules.

[0067] The microcapsule includes a first microcapsule and a second microcapsule. The first microcapsule includes a first core material and a first wall material covering the first core material, the first core material includes calcium carbonate, and the first wall material includes polysulfone. The second microcapsule includes a second core material and a second wall material covering the second core material, the second core material includes sodium alginate, and the second wall material includes polysulfone. The mass proportion of calcium carbonate in the first microcapsule is 25%, and the mass proportion of sodium alginate in the second microcapsule is 25%.

[0068] Figure 1 The SEM image of the microcapsules prepared in Example 1 is shown in FIG. Figure 1 It can be seen that the average particle size of the microcapsules is about 2 μm.

[0069] (2) Composite of microcapsules and matrix materials

[0070] See also Figure 2 , the microcapsules and the matrix material polyetheretherketone powder were mixed in a mass ratio of 5:100 to obtain mixture 3. Mixture 3 was placed in a graphite mold 1 and separated from the graphite mold 1 with graphite paper to reduce cross contamination. Mixture 3 was sintered according to the following sintering process: a pre-pressure of 1 MPa was applied to mixture 3 using a pressing head 2, and the air between the powders was removed with a vacuum pump to increase the compactness. Figure 2 and Figure 3 Mix 3 was then subjected to a pressure of 10 MPa and heated from 20°C to 330°C over 50 minutes, maintaining this temperature for 60 minutes. Next, the temperature was cooled from 330°C to 250°C over 20 minutes and maintained for 30 minutes. Finally, the temperature was cooled from 250°C to 20°C over 30 minutes. The sintered sample was treated with sandpaper, polishing cloth, and polishing fluid to obtain a relatively smooth surface, resulting in a self-lubricating composite material.

[0071] Example 2

[0072] The preparation method of the self-lubricating composite material is basically the same as that in Example 1, except that: in step (2), the microcapsules and the matrix material polyetheretherketone powder are mixed in a mass ratio of 7:100 to obtain a mixture.

[0073] Example 3

[0074] The preparation method of the self-lubricating composite material is basically the same as that in Example 1, except that: in step (2), the microcapsules and the matrix material polyetheretherketone powder are mixed in a mass ratio of 10:100 to obtain a mixture.

[0075] Example 4

[0076] The preparation method of the self-lubricating composite material is basically the same as that of Example 1, except that: in step (1.2), 3 g of sodium alginate is replaced by 6 g of sodium alginate, 3 g of polysulfone is replaced by 6 g of polysulfone, the mass ratio of calcium carbonate to sodium alginate is 1:2, the mass proportion of calcium carbonate in the first microcapsule is 16.7%, and the mass proportion of sodium alginate in the second microcapsule is 33.3%.

[0077] Comparative Example 1

[0078] The preparation method of the self-lubricating composite material comprises the following steps:

[0079] PEEK powder was placed in a graphite mold, and graphite paper was used to separate the PEEK powder and the graphite mold to reduce cross contamination. The PEEK powder was sintered according to the following sintering process: a pre-pressure of 1 MPa was applied to the PEEK powder, and the air between the powders was removed with a vacuum pump to increase the compactness. Subsequently, a pressure of 10 MPa was applied to the PEEK powder, and the temperature was heated from 20°C to 330°C within 50 minutes and kept warm for 60 minutes. Subsequently, the temperature was cooled from 330°C to 250°C in 20 minutes and kept warm for 30 minutes. Finally, the temperature was cooled from 250°C to 20°C in 30 minutes. The sintered sample was treated with sandpaper, polishing cloth, and polishing liquid to obtain a relatively smooth surface, thereby obtaining a self-lubricating composite material.

[0080] Test Case

[0081] Tribological tests were conducted using a UMT friction and wear tester. Specifically, a 10 mm diameter silicon nitride ball was used as the top surface, while the self-lubricating composite disc prepared in each Example or Comparative Example 1 was used as the bottom surface. The normal force during the tests was 15 N, and the rotational speeds were 30 rpm (r / min), 60 rpm, 120 rpm, 180 rpm, and 240 rpm.

[0082] The action mechanism diagram of the first microcapsule and the second microcapsule in the self-lubricating composite material prepared in Example 1 is shown in FIG. Figure 4 The test results are shown in Table 1 and Figure 5 shown.

[0083] Table 1

[0084]

[0085] like Figure 4 As shown, during the process of friction and wear, the first microcapsule with calcium carbonate as the first core material and the second microcapsule with sodium alginate as the second core material in Example 1 are worn, releasing the first core material and the second core material therein, and calcium carbonate and sodium alginate quickly form a hydrogel on the friction surface under the lubrication of water, fix the water molecule layer, and separate the rough peaks in contact with the heavy-load area, thereby reducing friction and wear.

[0086] From Table 1 and Figure 5It can be seen that under the same rotation speed conditions, compared with Comparative Example 1, the friction coefficient of the self-lubricating composite materials of Examples 1 to 4 is relatively small, indicating that the self-lubricating composite material provided by the present application includes a matrix material and microcapsules, the matrix material includes a first polymer, the microcapsules include first microcapsules and second microcapsules, the first microcapsules include a first core material and a first wall material covering the first core material, the first core material includes calcium salt, the second microcapsules include a second core material and a second wall material covering the second core material, and the second core material includes one or more of sodium alginate and polyvinyl alcohol, which can effectively reduce the friction loss of water-lubricated bearings and extend their service life.

[0087] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The above-described embodiments merely represent several implementation methods of the present application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims, and the specification may be used to interpret the content of the claims.

Claims

1. A self-lubricating composite material, characterized in that: The invention comprises a matrix material and microcapsules dispersed in the matrix material, wherein the matrix material comprises a first polymer, the microcapsules comprise a first microcapsule and a second microcapsule, the first microcapsule comprises a first core material and a first wall material covering the first core material, the first core material comprises a calcium salt, the second microcapsule comprises a second core material and a second wall material covering the second core material, and the second core material comprises one or more of sodium alginate and polyvinyl alcohol.

2. The self-lubricating composite material according to claim 1, characterized in that The self-lubricating composite material has one or more of the following characteristics: (1) The mass ratio of the calcium salt to at least one of the sodium alginate and the polyvinyl alcohol is 1:2 to 1:1; (2) The calcium salt includes one or more of calcium carbonate, calcium chloride and calcium lactate.

3. The self-lubricating composite material according to claim 1 or 2, characterized in that: The mass ratio of the microcapsules to the matrix material is (3-10):

100.

4. The self-lubricating composite material according to claim 1 or 2, characterized in that: The self-lubricating composite material has one or more of the following characteristics: (1) The mass proportion of the calcium salt in the first microcapsule is 15% to 50%; (2) The mass proportion of at least one of the sodium alginate and the polyvinyl alcohol in the second microcapsule is 33% to 50%.

5. The self-lubricating composite material according to claim 1 or 2, characterized in that: The self-lubricating composite material has one or more of the following characteristics: (1) The first polymer includes one or more of polyetheretherketone, polyurethane, ultra-high molecular weight polyethylene, nylon, and polytetrafluoroethylene, and the molecular weight of the ultra-high molecular weight polyethylene is 1.5 million Daltons to 8 million Daltons; (2) The first core material and the second core material each independently include a second polymer, and the second polymer includes one or more of polysulfone and polymethyl methacrylate.

6. A method for preparing a self-lubricating composite material, characterized in that: The steps include: Mixing a matrix material with microcapsules to obtain a mixture; the matrix material includes a first polymer, the microcapsules include first microcapsules and second microcapsules, the first microcapsules include a first core material and a first wall material covering the first core material, the first core material includes a calcium salt, the second microcapsules include a second core material and a second wall material covering the second core material, the second core material includes one or more of sodium alginate and polyvinyl alcohol; The mixed material is subjected to vacuum sintering treatment to obtain the self-lubricating composite material.

7. The method for preparing the self-lubricating composite material according to claim 6, characterized in that: The step of vacuum sintering the mixture includes: applying a pressure of 1MPa~10MPa to the mixture to remove air in the mixture, then keeping the mixture at 140℃~330℃ for 20min~60min, and then keeping the mixture at 120℃~250℃ for 10min~30min.

8. The method for preparing the self-lubricating composite material according to claim 6, characterized in that: The preparation method satisfies one or more of the following conditions: (1) The mass ratio of the calcium salt to at least one of the sodium alginate and the polyvinyl alcohol is 1:2 to 1:1; (2) The calcium salt includes one or more of calcium carbonate, calcium chloride and calcium lactate.

9. The method for preparing the self-lubricating composite material according to any one of claims 6 to 8, characterized in that: The mass ratio of the microcapsules to the matrix material is (3-10):

100.

10. A water-lubricated bearing, characterized in that: The invention comprises at least one of the self-lubricating composite material according to any one of claims 1 to 5 and the self-lubricating composite material prepared by the preparation method according to any one of claims 6 to 9.

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