Solid-liquid synergetic lubricating microcapsule and preparation method thereof, and self-lubricating composite material and preparation method thereof

Abstract

The invention relates to the technical field of self-lubricating materials, in particular to a solid-liquid synergistic lubrication microcapsule and a preparation method thereof, and a self-lubricating composite material and a preparation method thereof. The solid-liquid synergistic lubrication microcapsule comprises a core material and a shell material coating the core material; the core material comprises a liquid lubricant and a solid filler dispersed in the liquid lubricant, and the shell material comprises phthalazinone polyarylether resin. According to the invention, the phthalazinone polyarylether resin is used as the shell material of the microcapsule, so that the microcapsule has excellent high-temperature resistance and can be used in a high-temperature scene, and the application range of the organic wall material microcapsule is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of self-lubricating materials, and in particular to a solid-liquid synergistic lubricating microcapsule and its preparation method, a self-lubricating composite material and its preparation method. Background Art

[0002] In modern industry, during the operation of many mechanical components, the wear caused by friction not only reduces the service life of the equipment, but also increases the maintenance cost and energy consumption. In order to save energy, improve production efficiency, and extend the service life of materials, it is necessary to solve the problems of friction, wear, and lubrication protection, and the application of lubrication technology is one of the effective measures to solve this problem.

[0003] A microcapsule is a new type of lubricant filler with a core-shell structure. The shell material of the microcapsule is called the wall material, and the material embedded inside the cavity of the wall material is called the core material. This structure enables the core material to be effectively separated from the external environment, avoiding the influence of factors such as external temperature, pressure, ultraviolet rays, and pH value. This significantly improves the stability and its own performance of the core material under the protection of the outer wall. Microcapsules can be compounded with various polymer matrix materials and significantly reduce the friction coefficient and wear rate of the matrix materials. During the actual application process, due to the action of external force, friction, temperature rise, or radiation, etc., the internal core material lubricant of the microcapsule will be released, forming an effective lubricating film at the friction interface, thereby playing a role and effect of reducing friction and wear resistance.

[0004] Since the wall material of the microcapsule plays a very important role in sealing and protecting the core material, it has a long service life and recyclability during the actual application process. However, the conventional wall materials (such as polysulfone resin) in the prior art have insufficient heat resistance, which limits their application in high-temperature scenarios. Therefore, it is of great significance to study a high-temperature-resistant microcapsule. Summary of the Invention

[0005] Aiming at the above deficiencies existing in the prior art, the purpose of the present invention is to provide a solid-liquid synergistic lubricating microcapsule and its preparation method, a self-lubricating composite material and its preparation method. By using a heteroarylene biphenyl polyarylether resin as the shell material of the microcapsule, the microcapsule of the present invention has excellent high-temperature resistance, enabling it to be used in high-temperature scenarios and expanding the application range of organic wall material microcapsules.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a solid-liquid synergistic lubricating microcapsule, the solid-liquid synergistic lubricating microcapsule includes a core material and a shell material covering the core material, the core material includes a liquid lubricant and solid fillers dispersed in the liquid lubricant, and the shell material includes a heteroarylene biphenyl polyarylether resin.

[0008] By using the heterophthalophenylene polyarylether resin as the shell material of the microcapsule, the microcapsule has excellent high-temperature resistance, enabling it to be used in high-temperature scenarios and expanding the application range of the microcapsule with an organic wall material.

[0009] Further, the heterophthalophenylene polyarylether resin includes at least one of heterophthalophenylene copolyarylethersulfone, heterophthalophenylene polyarylether nitrile, heterophthalophenylene polyarylethersulfone, heterophthalophenylene copolyarylether nitrile, and heterophthalophenylene polyarylether nitrile sulfone.

[0010] Further, the structural formula of the heterophthalophenylene copolyarylethersulfone is:

[0011]

[0012] Wherein, R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, a phenyl group, a phenoxy group, an alkyl group, or an alkoxy group, and both the alkyl group and the alkoxy group contain at least 1 carbon atom. The structures of R1, R2, R3, and R4 are the same or different, m≥2, and n≥2;

[0013] And / or, the general structural formula of the heterophthalophenylene polyarylethersulfone, the heterophthalophenylene polyarylether nitrile, and the heterophthalophenylene polyarylether nitrile sulfone is:

[0014]

[0015] Wherein, Ar is: R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, a phenyl group, a phenoxy group, an alkyl group, or an alkoxy group, and both the alkyl group and the alkoxy group contain at least 1 carbon atom. The structures of R1, R2, R3, and R4 are the same or different;

[0016] In the general structural formula of the heterophthalophenylene polyarylethersulfone, a≥3 and b = 0;

[0017] In the general structural formula of the heterophthalophenylene polyarylether nitrile, a = 0 and b≥3;

[0018] In the general structural formula of the heterophthalophenylene polyarylether nitrile sulfone, a≥3 and b≥3;

[0019] And / or, the structural formula of the heterophthalophenylene copolyarylether nitrile is:

[0020]

[0021] Wherein, R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, a phenyl group, a phenoxy group, an alkyl group, or an alkoxy group, and both the alkyl group and the alkoxy group contain at least 1 carbon atom. The structures of R1, R2, R3, and R4 are the same or different, m≥2, and n≥2.

[0022] Further, the liquid lubricant includes at least one of polyol ester lubricating oil, ionic liquid lubricating oil, polyalphaolefin, perfluoropolyether, silicone oil, and paraffin oil;

[0023] and / or, the solid filler includes at least one of polytetrafluoroethylene, layered zirconium phosphate, nano silicon carbide, carbon nanotubes, nano silicon dioxide, hexagonal boron nitride (h-BN), and oil-containing nano-capsules;

[0024] and / or, the mass ratio of the solid filler to the liquid lubricant is (0.01 - 0.3):1.

[0025] Further, the oil-containing nano-capsules use hollow mesoporous carbon nanospheres as the container and lubricating oil as the core material, and the lubricating oil includes at least one of polyol ester lubricating oil, ionic liquid lubricating oil, polyalphaolefin, perfluoropolyether, silicone oil, and paraffin oil.

[0026] In a second aspect, the present invention provides a method for preparing the solid-liquid synergistic lubricating micro-capsules as described in the first aspect, and the preparation method includes the following steps:

[0027] S1. Add the solid filler to the liquid lubricant and stir evenly to obtain core material A;

[0028] S2. Dissolve the core material A and the shell material in an organic solvent and stir evenly to obtain oil phase solution B;

[0029] S3. Dissolve the surfactant in water and stir evenly to obtain aqueous phase solution C;

[0030] S4. Disperse the oil phase solution B into the aqueous phase solution C and stir for emulsification to volatilize the organic solvent. After the shell material precipitates, filter to obtain the solid-liquid synergistic lubricating micro-capsules.

[0031] Further, in step S2, the mass ratio of the core material A to the shell material is (0.2 - 2):1;

[0032] and / or, the organic solvent includes at least one of dichloromethane and chloroform;

[0033] and / or, in step S2, the mass ratio of the shell material to the volume of the organic solvent is 1:(20 - 40) g / mL;

[0034] and / or, the surfactant includes at least one of polyvinyl alcohol, Tween 80, sodium dodecylbenzenesulfonate, ammonium dodecyl sulfate, cetyltrimethylammonium bromide, gelatin, gum arabic, and lignin;

[0035] And / or, in step S3, the ratio of the mass of the surfactant to the volume of the water is 8:(400 - 800) g / mL.

[0036] Furthermore, in step S4, the rotation speed of the stirring and emulsifying is 400 - 800 r / min, and the time of the stirring and emulsifying is 3 - 6 hours;

[0037] And / or, the temperature of the stirring and emulsifying is 80% - 90% of the boiling point of the organic solvent.

[0038] In a third aspect, the present invention provides a self-lubricating composite material, which includes microcapsules and a heterophthaloyl biphenyl polyarylether resin. The microcapsules include the solid-liquid synergistic lubricating microcapsules described in the first aspect or the solid-liquid synergistic lubricating microcapsules prepared by the preparation method described in the second aspect.

[0039] In a fourth aspect, the present invention provides a preparation method of the self-lubricating composite material as described in the third aspect. The preparation method includes the following steps:

[0040] Mix the microcapsules and the heterophthaloyl biphenyl polyarylether resin to obtain a mixture;

[0041] Perform a shaping process on the mixture to obtain the self-lubricating composite material.

[0042] Compared with the prior art, the beneficial effects of the present invention at least include one of the following:

[0043] By using the heterophthaloyl biphenyl polyarylether resin as the shell material of the microcapsules, the present invention enables the microcapsules to have excellent high-temperature resistance, enabling them to be used in high-temperature scenarios and expanding the application range of the organic wall material microcapsules. Description of the Drawings

[0044] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required to be used in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 SEM diagram of the solid-liquid synergistic lubricating microcapsules provided in Example 1 of the present invention;

[0046] Figure 2 Schematic diagram of the change of the friction coefficient (μ) of the self-lubricating composite material provided in Example 1 of the present invention with time at 300 °C. Specific Embodiments

[0047] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will describe the technical solutions in the embodiments of the present invention clearly and completely in conjunction with the embodiments of the present invention. Those skilled in the art should understand that the described embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention. For the process parameters without specific conditions noted in the following embodiments, they are usually in accordance with conventional conditions. Unless otherwise specified, all raw materials can be purchased from the market or are common materials in this industry.

[0048] In the ranges disclosed in the present invention, the endpoints and any values of the ranges are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0049] In a first aspect, the present invention provides a solid-liquid synergistic lubrication microcapsule. The solid-liquid synergistic lubrication microcapsule includes a core material and a shell material covering the core material. The core material includes a liquid lubricant and solid fillers dispersed in the liquid lubricant, and the shell material includes a heteroarylene biphenyl polyarylether resin.

[0050] By using a heteroarylene biphenyl polyarylether resin as the shell material of the microcapsule, the present invention enables the microcapsule to have excellent high-temperature resistance, enabling it to be used in high-temperature scenarios (the use temperature can reach 300 °C), expanding the applicable range of organic wall material microcapsules.

[0051] The solid fillers are uniformly dispersed in the liquid lubricating oil to form a solid-liquid composite core material, which has a synergistic effect and significantly improves the lubrication performance and wear resistance of the material. During the friction process, the liquid lubricating oil can form a lubricating film on the friction surface to reduce the friction coefficient, while the solid fillers can enhance the load-bearing capacity and anti-wear performance of the lubricating film.

[0052] In the above solid-liquid synergistic lubrication microcapsule, as an alternative embodiment, the heteroarylene biphenyl polyarylether resin includes at least one of poly(phthalazinone ether sulfone ketone) (PPBES), poly(phthalazinone ether nitrile) (PPEN), poly(phthalazinone ether sulfone) (PPES), poly(phthalazinone biphenyl ether nitrile) (PPBEN), poly(phthalazinone ether nitrile sulfone) (PPENS), and is preferably poly(phthalazinone ether sulfone ketone) (PPBES). When the shell material is poly(phthalazinone ether sulfone ketone) (PPBES), the prepared capsule structure is more regular.

[0053] In the above solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the structural formula of the poly(phthalazinone ether sulfone) (PPBES) is as follows:

[0054]

[0055] Wherein, R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, a phenyl group, a phenoxy group, an alkyl group, or an alkoxy group. The alkyl group or the alkoxy group contains at least 1 carbon atom, and the structures of R1, R2, R3, and R4 are the same or different, m≥2, n≥2.

[0056] In the above solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the general structural formulas of the poly(phthalazinone ether sulfone) (PPES), the poly(phthalazinone ether nitrile) (PPEN), and the poly(phthalazinone ether nitrile sulfone) (PPENS) are as follows:

[0057]

[0058] Wherein, Ar is: R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, a phenyl group, a phenoxy group, an alkyl group, or an alkoxy group. The alkyl group or the alkoxy group contains at least 1 carbon atom, and the structures of R1, R2, R3, and R4 are the same or different;

[0059] In the general structural formula of the poly(phthalazinone ether sulfone) (PPES), a≥3, b = 0;

[0060] In the general structural formula of the poly(phthalazinone ether nitrile) (PPEN), a = 0, b≥3;

[0061] In the general structural formula of the poly(phthalazinone ether nitrile sulfone) (PPENS), a≥3, b≥3.

[0062] In the above solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the structural formula of the poly(phthalazinone ether nitrile) (PPBEN) is as follows:

[0063]

[0064] Wherein, R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, a phenyl group, a phenoxy group, an alkyl group, or an alkoxy group. The alkyl group or the alkoxy group contains at least 1 carbon atom, and the structures of R1, R2, R3, and R4 are the same or different, m≥2, n≥2.

[0065] In the above solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the liquid lubricant includes at least one of polyol ester lubricating oil, ionic liquid lubricating oil, poly-α-olefin, perfluoropolyether, silicone oil, and paraffin oil.

[0066] In the above solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the solid filler includes at least one of polytetrafluoroethylene (PTFE), layered zirconium phosphate, nano silicon carbide (SiC), carbon nanotubes (CNT), nano silicon dioxide (SiO2), hexagonal boron nitride (h-BN), and oil-containing nano-capsules. To further improve the lubricating performance of the solid-liquid synergistic lubricating microcapsules, oil-containing nano-capsules are preferably used.

[0067] In the above solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the oil-containing nano-capsules use hollow mesoporous carbon nanospheres as the container and lubricating oil as the core material. The lubricating oil includes at least one of polyol ester lubricating oil, ionic liquid lubricating oil, polyalphaolefin, perfluoropolyether, silicone oil, and paraffin oil.

[0068] In the above solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the preparation method of the oil-containing nano-capsules includes the following steps:

[0069] S1. React TEOS (tetraethyl orthosilicate) and dopamine hydrochloride in a solvent in the presence of a base. After the reaction is completed, dry and then calcine, and finally etch away SiO2 with an alkaline aqueous solution to obtain the hollow mesoporous carbon nanospheres;

[0070] S2. Use the vacuum impregnation method to fully impregnate the lubricating oil, and obtain the oil-containing nano-capsules after drying. In the above solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the mass ratio of the solid filler to the liquid lubricant is (0.01-0.3):1, and can be, for example, 0.01:1, 0.05:1, 0.1:1, 0.2:1, or 0.3:1.

[0071] In a second aspect, the present invention provides a preparation method of the solid-liquid synergistic lubricating microcapsules as described in the first aspect. The preparation method includes the following steps:

[0072] S1. Add the solid filler to the liquid lubricant and stir evenly to obtain core material A;

[0073] S2. Dissolve the core material A and the shell material in an organic solvent and stir evenly to obtain oil phase solution B;

[0074] S3. Dissolve the surfactant in water and stir evenly to obtain aqueous phase solution C;

[0075] S4. Disperse the oil phase solution B into the aqueous phase solution C and stir to emulsify, volatilize the organic solvent, filter after the shell material precipitates to obtain the solid-liquid synergistic lubricating microcapsules.

[0076] In the above method for preparing the solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, in step S2, the mass ratio of the core material A to the shell material is (0.2-2):1.

[0077] In the above method for preparing the solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the organic solvent includes at least one of dichloromethane and chloroform.

[0078] In the above method for preparing the solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, in step S2, the ratio of the mass of the shell material to the volume of the organic solvent is 1:(20-40) g / mL (for example, it can be 1:20, 1:30 or 1:40).

[0079] In the above method for preparing the solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the surfactant includes at least one of polyvinyl alcohol, Tween 80, sodium dodecylbenzenesulfonate, ammonium dodecyl sulfate, cetyltrimethylammonium bromide, gelatin, gum arabic and lignin.

[0080] In the above method for preparing the solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, in step S3, the ratio of the mass of the surfactant to the volume of water is 8:(400-800) g / mL, for example, it can be 8:400 g / mL, 8:500 g / mL, 8:600 g / mL, 8:700 g / mL or 8:800 g / mL.

[0081] In the above method for preparing the solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, in step S4, the rotation speed of the stirring and emulsifying is 400-800 r / min, for example, it can be 400 r / min, 450 r / min, 500 r / min, 650 r / min or 800 r / min, and the time of the stirring and emulsifying is 3-6 hours. When the stirring speed is too high, the capsules are likely to rupture under the action of shear force; when the stirring speed is relatively low, the solvent evaporation speed is slow, affecting the efficiency, and at the same time, it will also cause the size distribution of the formed microcapsules to be uneven and unable to form a uniform spherical structure, thus affecting its lubricating performance and the stability of the lubricating performance.

[0082] In the above method for preparing the solid-liquid synergistic lubricating microcapsules, as an alternative embodiment, the temperature of the stirring and emulsifying is 80%-90% of the boiling point of the organic solvent, for example, it can be 80%, 82%, 84%, 86%, 88% or 90%. When the temperature is too high, the solvent evaporates too fast, which is likely to cause the capsules to perforate, thus reducing the content of the core material.

[0083] In a third aspect, the present invention provides a self-lubricating composite material, which includes microcapsules and a heteroarylene biphenyl polyarylether resin. The microcapsules include the solid-liquid synergistic lubricating microcapsules described in the first aspect or the solid-liquid synergistic lubricating microcapsules prepared by the preparation method described in the second aspect.

[0084] The self-lubricating composite material provided by the present invention improves the tribological properties of the resin-based composite material by using microcapsules with a shell material including a heteroarylene biphenyl polyarylether resin as wear-resistant self-lubricating fillers, so that the self-lubricating composite material has excellent high-temperature resistance and lubrication performance.

[0085] Compared with the prior art, the self-lubricating composite material provided by the present invention has the following advantages: First, with a heteroarylene biphenyl polyarylether resin as the matrix, it has good heat resistance, chemical stability and mechanical properties, enabling the composite material to maintain stable lubrication performance at 300 °C. Second, the solid fillers are uniformly dispersed in the liquid lubricating oil to form a solid-liquid composite core material, which has a synergistic effect and significantly improves the lubrication performance and wear resistance of the material. During the friction process, the liquid lubricating oil can form a lubricating film on the friction surface to reduce the friction coefficient, while the solid fillers can enhance the load-bearing capacity and anti-wear performance of the lubricating film. In addition, using a heteroarylene biphenyl polyarylether resin as the capsule shell material can effectively protect the core material and solid fillers, improving the stability and service life of the modified microcapsules. Finally, the preparation method of this composite material is simple, easy to industrialize, and has broad application prospects.

[0086] In the above self-lubricating composite material, as an optional implementation manner, the mass ratio of the microcapsules to the heteroarylene biphenyl polyarylether resin is (5 - 30):(95 - 70), and for example, it can be 5:95, 10:90, 20:80 or 30:70.

[0087] In the above self-lubricating composite material, as an alternative embodiment, the naphthalene biphenyl polyarylether resin includes at least one of naphthalene biphenyl copolyarylether sulfone (PPBES), naphthalene biphenyl polyarylether ketone (PPEK), naphthalene biphenyl polyarylether sulfone (PPES), naphthalene biphenyl polyarylether nitrile (PPEN), naphthalene biphenyl polyarylether ketone ketone (PPEKK), naphthalene biphenyl polyarylether sulfone ketone (PPESK), naphthalene biphenyl polyarylether nitrile sulfone (PPENS), naphthalene biphenyl polyarylether nitrile ketone ketone (PPENKK), naphthalene biphenyl polyarylether sulfone ketone ketone (PPESKK), naphthalene biphenyl polyarylether nitrile sulfone ketone (PPENSK), naphthalene biphenyl polyarylether nitrile sulfone ketone ketone (PPENSKK), bis(diazafluorenone) polyarylether ketone (PDPEK), bis(diazafluorenone) polyarylether sulfone (PDPES), bis(diazafluorenone) polyarylether nitrile (PDPEN), bis(diazafluorenone) polyarylether ketone ketone (PDPEKK), bis(diazafluorenone) polyarylether sulfone ketone (PDPESK), bis(diazafluorenone) polyarylether nitrile sulfone (PDPENS), bis(diazafluorenone) polyarylether nitrile ketone ketone (PDPENKK), bis(diazafluorenone) polyarylether sulfone ketone ketone (PDPESKK), bis(diazafluorenone) polyarylether nitrile sulfone ketone (PDPENSK), and bis(diazafluorenone) polyarylether nitrile sulfone ketone ketone (PDPENSKK).

[0088] In the above self-lubricating composite material, as an alternative embodiment, A) the structural formula of the naphthalene biphenyl polyarylether ketone (PPEK) is:

[0089]

[0090] wherein, R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, a phenyl group, a phenoxy group, an alkyl group, or an alkoxy group, the alkyl group or the alkoxy group contains at least 1 carbon atom, the structures of R1, R2, R3, and R4 are the same or different, and n≥2;

[0091] B) The general structural formulas of the naphthalene biphenyl polyarylether sulfone (PPES), the naphthalene biphenyl polyarylether nitrile (PPEN), the naphthalene biphenyl polyarylether ketone ketone (PPEKK), the naphthalene biphenyl polyarylether sulfone ketone (PPESK), the naphthalene biphenyl polyarylether nitrile sulfone (PPENS), the naphthalene biphenyl polyarylether nitrile ketone ketone (PPENKK), the naphthalene biphenyl polyarylether sulfone ketone ketone (PPESKK), the naphthalene biphenyl polyarylether nitrile sulfone ketone (PPENSK), and the naphthalene biphenyl polyarylether nitrile sulfone ketone ketone (PPENSKK) are:

[0092]

[0093] wherein, Ar is: R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, phenyl, phenoxy, alkyl, or alkoxy, where the alkyl or alkoxy each contains at least 1 carbon atom, and the structures of R1, R2, R3, and R4 are the same or different;

[0094] In the general structural formula of the naphthalene - biphenyl polyaryl ether sulfone (PPES), a ≥ 3, b = 0, c = 0, d = 0;

[0095] In the general structural formula of the naphthalene - biphenyl polyaryl ether nitrile (PPEN), a = 0, b = 0, c ≥ 3, d = 0;

[0096] In the general structural formula of the naphthalene - biphenyl polyaryl ether ketone - ketone (PPEKK), a = 0, b = 0, c = 0, d ≥ 3;

[0097] In the general structural formula of the naphthalene - biphenyl polyaryl ether sulfone - ketone (PPESK), a ≥ 3, b ≥ 3, c = 0, d = 0;

[0098] In the general structural formula of the naphthalene - biphenyl polyaryl ether nitrile - sulfone (PPENS), a ≥ 3, b = 0, c ≥ 3, d = 0;

[0099] In the general structural formula of the naphthalene - biphenyl polyaryl ether nitrile - ketone - ketone (PPENKK), a = 0, b = 0, c ≥ 3, d ≥ 3;

[0100] In the general structural formula of the naphthalene - biphenyl polyaryl ether sulfone - ketone - ketone (PPESKK), a ≥ 3, b = 0, c = 0, d ≥ 3;

[0101] In the general structural formula of the naphthalene - biphenyl polyaryl ether nitrile - sulfone - ketone (PPENSK), a ≥ 3, b ≥ 3, c ≥ 3, d = 0;

[0102] In the general structural formula of the naphthalene - biphenyl polyaryl ether nitrile - sulfone - ketone - ketone (PPENSKK), a ≥ 3, b = 0, c ≥ 3, d ≥ 3;

[0103] C) The general structural formulas of the bis - phthalazinone polyaryl ether ketone (PDPEK), the bis - phthalazinone polyaryl ether sulfone (PDPES), the bis - phthalazinone polyaryl ether nitrile (PDPEN), the bis - phthalazinone polyaryl ether ketone - ketone (PDPEKK), the bis - phthalazinone polyaryl ether sulfone - ketone (PDPESK), the bis - phthalazinone polyaryl ether nitrile - sulfone (PDPENS), the bis - phthalazinone polyaryl ether nitrile - ketone - ketone (PDPENKK), the bis - phthalazinone polyaryl ether sulfone - ketone - ketone (PDPESKK), the bis - phthalazinone polyaryl ether nitrile - sulfone - ketone (PDPENSK), and the bis - phthalazinone polyaryl ether nitrile - sulfone - ketone - ketone (PDPENSKK) are:

[0104]

[0105] Among them, Ar is

[0106] one or more of;

[0107] In the general structural formula of the said phthalazinone polyaryletherketone (PDPEK), a = 0, b ≥ 3, c = 0, d = 0;

[0108] In the general structural formula of the said phthalazinone polyarylethersulfone (PDPES), a ≥ 3, b = 0, c = 0, d = 0;

[0109] In the general structural formula of the said phthalazinone polyarylethernitrile (PDPEN), a = 0, b = 0, c ≥ 3, d = 0;

[0110] In the general structural formula of the said phthalazinone polyaryletherketoneketone (PDPEKK), a = 0, b = 0, c = 0, d ≥ 3;

[0111] In the general structural formula of the said phthalazinone polyarylethersulfoneketone (PDPESK), a ≥ 3, b ≥ 3, c = 0, d = 0;

[0112] In the general structural formula of the said phthalazinone polyarylethernitrilesulfone (PDPENS), a ≥ 3, b = 0, c ≥ 3, d = 0;

[0113] In the general structural formula of the said phthalazinone polyarylethernitrileketoneketone (PDPENKK), a = 0, b = 0, c ≥ 3, d ≥ 3;

[0114] In the general structural formula of the said phthalazinone polyarylethersulfoneketoneketone (PDPESKK), a ≥ 3, b = 0, c = 0, d ≥ 3;

[0115] In the general structural formula of the said phthalazinone polyarylethernitrilesulfoneketone (PDPENSK), a ≥ 3, b ≥ 3, c ≥ 3, d = 0;

[0116] In the general structural formula of the said phthalazinone polyarylethernitrilesulfoneketoneketone (PDPENSKK), a ≥ 3, b = 0, c ≥ 3, d ≥ 3.

[0117] Fourthly, the present invention provides a preparation method of a self-lubricating composite material as described in the third aspect, and the preparation method includes the following steps:

[0118] Mix the said microcapsules and the phthalazinyl biphenyl polyarylether resin to obtain a mixture;

[0119] Perform a molding treatment on the said mixture to obtain the said self-lubricating composite material (a microcapsule-modified high-temperature resistant self-lubricating composite material).

[0120] In the preparation method of the above self-lubricating composite material, as an alternative embodiment, the mixing includes one of solution mixing, mechanical mixing, and ball milling mixing.

[0121] In the preparation method of the above self-lubricating composite material, as an alternative embodiment, the shaping process includes one of compression molding and injection molding.

[0122] In the preparation method of the above self-lubricating composite material, as an alternative embodiment, the compression molding includes adding the mixture according to the requirements of the sample size, and then placing the mold on a hot press for compression molding. The procedure of the compression molding is to start heating at a rate of 2-4°C / min under a pressure of 1-5 MPa, keep the temperature at 260-280°C for 10-30 min, relieve the pressure and exhaust gas 2-5 times, and then heat up to 300-410°C (for example, 300°C, 320°C, 340°C, 360°C, 380°C, 410°C) at a rate of 1-3°C / min, and then pressurize to 3-7 MPa (for example, 3 MPa, 5 MPa, 7 MPa), and keep the pressure and temperature for 30-70 min (for example, 30 min, 50 min, 70 min); when the temperature drops below 150°C (including 150°C), relieve the pressure and demold to obtain the laminate of the self-lubricating composite material.

[0123] In the preparation method of the above self-lubricating composite material, as an alternative embodiment, the injection molding includes: extruding, granulating, and injection molding the mixture through a twin-screw extruder to obtain a standard sample bar. Among them, the extrusion temperature of the twin-screw extruder is 290°C - 410°C (for example, 290°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 410°C), the extrusion rate is 10-90 mm / s (for example, 10 mm / s, 15 mm / s, 30 mm / s, 45 mm / s, 60 mm / s, 80 mm / s, 90 mm / s), the injection temperature is 290°C - 410°C (for example, 290°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 410°C), the screw length-diameter ratio is 15:1 - 30:1 (for example, 15:1, 20:1, 22:1, 24:1, 28:1, 30:1), the injection speed is 30-100 mm / s (for example, 30 mm / s, 35 mm / s, 60 mm / s, 75 mm / s, 80 mm / s, 90 mm / s, 100 mm / s), and the injection mold clamping pressure is 45-90 MPa (for example, 45 MPa, 55 MPa, 70 MPa, 80 MPa, 90 MPa).

[0124] The present invention will be further described in detail below with specific examples and comparative examples.

[0125] In the following examples and comparative examples:

[0126] The preparation method of the oil-containing nanocapsules comprises the following steps: Stir 50 ml of deionized water, 250 ml of ethanol and 10 ml of ammonia water evenly in a beaker. Subsequently, slowly add 10 ml of TEOS, continuously stir for 20 min, then add 3 g of dopamine hydrochloride and react for 11 h. After centrifugation, washing and drying, nanospheres of SiO2 coated with PDA (polydopamine) are obtained; Then place the nanospheres in a tubular furnace, calcine them at 800 °C under a N2 atmosphere for 4 hours, and then etch away SiO2 with an aqueous solution of NaOH (2M) to obtain hollow mesoporous carbon nanospheres; The nanocapsules are prepared by the vacuum impregnation method, and the preparation method is as follows: Add 10 g of perfluoropolyether, 10 g of fluorinated liquid (perfluoro-4-methyl-2-pentene) and 1 g of HMCS (hollow mesoporous carbon nanospheres) into a beaker, ultrasonically disperse for 30 min, then let it stand for 2 h, and then place it in a vacuum oven at 35 °C, and keep it at a vacuum degree of 0.1 MPa for 9 h, so that the fluorinated liquid volatilizes and the perfluoropolyether is fully impregnated. After washing and drying, nanocapsules of perfluoropolyether lubricating oil are obtained.

[0127] The resin of heterophthaloyl biphenyl polyarylether sulfone (PPES) (Mn = 26000 g / mol) is provided by Dalian Poly New Materials Co., Ltd., and its structural formula is:

[0128]

[0129] Among them, Ar is: R1, R2, R3, and R4 are all hydrogen; a ≥ 3, b = 0.

[0130] The method for measuring the friction coefficient refers to the ASTM-G133 standard.

[0131] Example 1

[0132] This example provides a solid-liquid synergistic lubricating microcapsule. The solid-liquid synergistic lubricating microcapsule comprises a core material and a shell material coating the core material. The core material comprises a liquid lubricant and solid fillers dispersed in the liquid lubricant. The shell material is heterophthaloyl biphenyl copolyarylether sulfone. Among them, the liquid lubricant is phenyl silicone oil, the solid filler is oil-containing nanocapsules, and the heterophthaloyl biphenyl copolyarylether sulfone (Mn = 31000 g / mol) is provided by Dalian Poly New Materials Co., Ltd., and its structural formula is:

[0133]

[0134] Among them, R1, R2, R3, and R4 are all hydrogen; m ≥ 3, n ≥ 3.

[0135] The preparation method of the solid-liquid synergistic lubrication microcapsules provided in this embodiment includes the following steps: Weigh 0.5 g of oil-containing nano-capsule solid filler, add it to 5 g of phenyl silicone oil, and ultrasonically disperse for 30 min to uniformly disperse the solid filler in the silicone oil, obtaining mixed core material A. Dissolve core material A and 3 g of heterocyclic naphthalene-based copolyarylether sulfone resin in 120 mL of dichloromethane, and mechanically stir for 2 h to obtain oil-phase solution B. Add surfactants (3 g of gelatin and 3 g of polyvinyl alcohol) and 500 ml of deionized water to a three-necked flask, and mechanically stir for 1 h to obtain aqueous solution C. Under high-speed stirring (500 r / min), slowly add oil-phase solution B to aqueous solution C, then stir at 35 °C at a speed of 500 r / min for 4 h, remove the organic solvent, and filter to obtain solid-liquid synergistic lubrication microcapsules. The mass percentage of the core material in the solid-liquid synergistic lubrication microcapsules is 65%.

[0136] Use a thermal analyzer to perform TGA tests on the microcapsules provided in this embodiment. Heat up to 310 °C at a heating rate of 20 °C / min, and then keep the temperature constant at 310 °C for 3 hours. The mass loss rate of the microcapsules provided in this embodiment is 10 wt%.

[0137] This embodiment provides a preparation method of a self-lubricating composite material, including the following steps:

[0138] Add 20 g of the solid-liquid synergistic lubrication microcapsules prepared in this embodiment and 80 g of PPES resin to 500 ml of ethanol solution, mechanically mix at 1000 r / min for 4 h, and then dry at 80 °C for 2 h to obtain a mixed material. Place the mixed material in a mold and form it by a molding process. Specifically: under a pressure of 1 MPa, start heating at a rate of 4 °C / min, keep the temperature at 270 °C for 10 min, relieve pressure and exhaust twice, then heat up to 310 °C at a rate of 2 °C / min, and then pressurize to 5 MPa and keep the pressure and temperature constant for 60 min. When the temperature drops to 150 °C, the pressure can be relieved and the mold can be removed to take out the pressed plate, that is, a high-temperature resistant self-lubricating composite material modified by solid-liquid synergistic lubrication microcapsules is obtained. The friction coefficient of this composite material at 300 °C is 0.08.

[0139] Figure 1 is the SEM image of the solid-liquid synergistic lubrication microcapsules prepared in this embodiment. It can be Figure 1 seen that the spherical structure of the capsules is relatively uniform, and the size is about 35 μm.

[0140] Figure 2 is the schematic diagram of the change of the friction coefficient (μ) of the self-lubricating composite material prepared in this embodiment with time at 300 °C. It can be Figure 2 seen that the change of the friction coefficient (μ) of the self-lubricating composite material prepared in Example 1 with time is relatively stable.

[0141] Example 2

[0142] The solid-liquid synergistic lubricating microcapsules provided in this example are basically the same as those in Example 1, except that the solid filler is polytetrafluoroethylene (PTFE).

[0143] The microcapsules provided in this example were subjected to TGA testing using a thermal analyzer. The temperature was raised to 310 °C at a heating rate of 20 °C / min, and then held at 310 °C for 3 hours. The mass loss rate of the microcapsules provided in this example was close to that of Example 1.

[0144] Refer to the preparation method of the self-lubricating composite material provided in Example 1 to prepare the self-lubricating composite material.

[0145] The friction coefficient of the composite material prepared in this example at 300 °C was 0.15.

[0146] Comparing Example 1 with this example, it can be seen that using oil-containing nanocapsules as the solid filler can make the lubricating performance of the microcapsules more excellent.

[0147] Example 3

[0148] The solid-liquid synergistic lubricating microcapsules provided in this example are basically the same as those in Example 1, except that the liquid lubricant is paraffin oil, and in the preparation method, the rotation speed of the stirring and emulsification is 400 r / min.

[0149] The microcapsules provided in this example were subjected to TGA testing using a thermal analyzer. The temperature was raised to 310 °C at a heating rate of 20 °C / min, and then held at 310 °C for 3 hours. The mass loss rate of the microcapsules provided in this example was close to that of Example 1.

[0150] Refer to the preparation method of the self-lubricating composite material provided in Example 1 to prepare the self-lubricating composite material.

[0151] The friction coefficient of the composite material prepared in this example at 300 °C was 0.087.

[0152] Example 4

[0153] The solid-liquid synergistic lubricating microcapsules provided in this example are basically the same as those in Example 1, except that the shell material is heteroarylene biphenyl polyarylether sulfone.

[0154] The microcapsules provided in this example were subjected to TGA testing using a thermal analyzer. The temperature was raised to 310 °C at a heating rate of 20 °C / min, and then held at 310 °C for 3 hours. The mass loss rate of the microcapsules provided in this example was close to that of Example 1.

[0155] Refer to the preparation method of the self-lubricating composite material provided in Example 1 to prepare the self-lubricating composite material.

[0156] The friction coefficient of the composite material prepared in this example at 300 °C is 0.12.

[0157] Example 5

[0158] The solid-liquid synergistic lubricating microcapsules provided in this example are basically the same as those in Example 1, except that the shell material is heterocyclic naphthalene-based polyarylether nitrile, and the heterocyclic naphthalene-based polyarylether nitrile (Mn = 18000 g / mol) is provided by Dalian Poly New Materials Co., Ltd., and the structural formula is:

[0159]

[0160] Among them, Ar is: R1, R2, R3, and R4 each independently represent hydrogen; a = 0, b ≥ 3.

[0161] The microcapsules provided in this example were subjected to TGA testing using a thermal analyzer, heated to 310 °C at a heating rate of 20 °C / min, and then held at 310 °C for 3 hours. The mass loss rate of the microcapsules provided in this example is close to that of Example 1.

[0162] Refer to the preparation method of the self-lubricating composite material provided in Example 1 to prepare the self-lubricating composite material.

[0163] The friction coefficient of the composite material prepared in this example at 300 °C is 0.13.

[0164] Example 6

[0165] The solid-liquid synergistic lubricating microcapsules provided in this example are exactly the same as those in Example 1.

[0166] The preparation method of the self-lubricating composite material provided in this example is basically the same as that in Example 1, except that the microcapsules are 30 g and the PPES is 70 g.

[0167] The friction coefficient of this composite material at 300 °C is 0.06.

[0168] Comparative Example 1

[0169] The solid-liquid synergistic lubricating microcapsules provided in this comparative example are basically the same as those in Example 1, except that the core material does not include solid fillers and only phenyl silicone oil is used as the core material.

[0170] Refer to the preparation method of the self-lubricating composite material provided in Example 1 to prepare the self-lubricating composite material.

[0171] The friction coefficient of the composite material provided in this comparative example at 300 °C is 0.22.

[0172] Comparing Example 1 with this comparative example, it can be seen that when the core material does not include solid fillers, the friction coefficient increases significantly.

[0173] Comparative Example 2

[0174] The solid-liquid synergistic lubricating microcapsules provided in this comparative example are basically the same as those in Example 1, except that the shell material is polysulfone resin (PSF), and the structural formula of this polysulfone resin (number average molecular weight is 30,000 g / mol) is:

[0175]

[0176] Refer to the preparation method of the self-lubricating composite material provided in Example 1 to prepare the self-lubricating composite material.

[0177] The friction coefficient of the composite material prepared in this comparative example at 300 °C is 0.29.

[0178] Use a thermal analyzer to perform TGA tests on the microcapsules provided in this comparative example. Heat up to 310 °C at a heating rate of 20 °C / min, and then keep it constant at 310 °C for 3 hours. The mass loss rate of the microcapsules provided in this comparative example is 43 wt%, which is significantly higher than that in Example 1, indicating that by using the heteroarylene biphenyl polyarylether resin as the shell material of the microcapsules in the present invention, the microcapsules have excellent high-temperature resistance, enabling them to be used in high-temperature scenarios and expanding the application range of organic wall material microcapsules.

[0179] Comparative Example 3

[0180] The preparation method of the solid-liquid synergistic lubricating microcapsules provided in this comparative example is basically the same as that in Example 1, except that the rotation speed of stirring and emulsifying is 200 r / min, and the stirring and emulsifying time is 6 hours, which specifically includes the following steps:

[0181] Weigh 0.5 g of oil-containing nano-capsule solid filler, add it to 5 g of phenyl silicone oil, and ultrasonically disperse for 30 min to make the solid filler evenly dispersed in the silicone oil to obtain the mixed core material A. Dissolve the core material A and 3 g of heteroarylene biphenyl copolyarylethersulfone resin in 120 mL of dichloromethane, and mechanically stir for 2 h to obtain the oil-phase solution B. Add surfactants (3 g of gelatin and 3 g of polyvinyl alcohol) and 500 ml of deionized water to a three-necked flask, and mechanically stir for 1 h to obtain the water-phase solution C. Under high-speed stirring (200 r / min), slowly add the oil-phase solution B to the water-phase solution C, and then stir at 200 r / min at 35 °C for 6 h. After removing the organic solvent, filter to obtain the solid-liquid synergistic lubricating microcapsules.

[0182] Refer to the preparation method of the self-lubricating composite material provided in Example 1 to prepare the self-lubricating composite material.

[0183] The friction coefficient of the composite material prepared in this comparative example at 300 °C is 0.17.

[0184] Compared with Example 1, the friction coefficient of the composite material prepared in this comparative example at 300 °C is significantly increased. The applicant found that when the stirring speed is small, the size distribution of the microcapsules formed is uneven, and a uniform spherical structure cannot be formed, thus affecting its lubrication performance.

[0185] Comparative Example 4

[0186] The preparation method of the solid-liquid synergistic lubricating microcapsules provided in this comparative example is basically the same as that of Example 1, except that it is stirred at a speed of 500 r / min for 3 h at 40 °C. The mass percentage of the core material in the solid-liquid synergistic lubricating microcapsules is 52%.

[0187] Refer to the preparation method of the self-lubricating composite material provided in Example 1 to prepare the self-lubricating composite material.

[0188] The friction coefficient of the composite material prepared in this comparative example at 300 °C is 0.20.

[0189] Compared with Example 1, the content of the core material in the microcapsules prepared in this comparative example is reduced. The applicant speculates that the reason may be that when the temperature is too high, methylene chloride volatilizes too fast, which easily causes perforation of the capsules, thus reducing the content of the core material.

[0190] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solid-liquid synergistic lubrication microcapsule, characterized in that The solid-liquid synergistic lubricating microcapsule includes a core material and a shell material coating the core material. The core material includes a liquid lubricant and solid fillers dispersed in the liquid lubricant, and the shell material includes a heteroarylene biphenyl polyarylether resin.

2. The solid-liquid synergistic lubricating microcapsule according to claim 1, wherein The heteroarylene biphenyl polyarylether resin includes at least one of heteroarylene biphenyl copolyarylethersulfone, heteroarylene biphenyl polyarylether nitrile, heteroarylene biphenyl polyarylethersulfone, heteroarylene biphenyl copolyarylether nitrile, and heteroarylene biphenyl polyarylether nitrile sulfone.

3. The solid-liquid synergistic lubricating microcapsule according to claim 2, wherein The structural formula of the heteroarylene biphenyl copolyarylethersulfone is: Wherein, R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, a phenyl group, a phenoxy group, an alkyl group, or an alkoxy group. The alkyl group or the alkoxy group contains at least 1 carbon atom, and the structures of R1, R2, R3, and R4 are the same or different, m≥2, n≥2; And / or, the general structural formula of the heteroarylene biphenyl polyarylethersulfone, the heteroarylene biphenyl polyarylether nitrile, and the heteroarylene biphenyl polyarylether nitrile sulfone is: wherein Ar is: R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, phenyl, phenoxy, alkyl, or alkoxy, said alkyl or said alkoxy each containing at least 1 carbon atom, and the structures of R1, R2, R3, and R4 are the same or different; In the general structural formula of the heteroarylene biphenyl polyarylethersulfone, a≥3, b = 0; In the general structural formula of the heteroarylene biphenyl polyarylether nitrile, a = 0, b≥3; In the general structural formula of the heteroarylene biphenyl polyarylether nitrile sulfone, a≥3, b≥3; And / or, the structural formula of the heteroarylene biphenyl copolyarylether nitrile is: Wherein, R1, R2, R3, and R4 each independently represent hydrogen, a halogen substituent, a phenyl group, a phenoxy group, an alkyl group, or an alkoxy group. The alkyl group or the alkoxy group contains at least 1 carbon atom, and the structures of R1, R2, R3, and R4 are the same or different, m≥2, n≥2.

4. The solid-liquid synergistic lubricating microcapsule according to claim 1, wherein The liquid lubricant includes at least one of polyol ester lubricating oil, ionic liquid lubricating oil, poly-α-olefin, perfluoropolyether, silicone oil, and paraffin oil; And / or, the solid filler includes at least one of polytetrafluoroethylene, layered zirconium phosphate, nano silicon carbide, carbon nanotubes, nano silicon dioxide, hexagonal boron nitride (h-BN), and oil-containing nano-capsules; And / or, the mass ratio of the solid filler to the liquid lubricant is (0.01 - 0.3):

1.

5. The solid-liquid synergistic lubricating microcapsule according to claim 4, characterized in that, The oil-containing nano-capsule uses a hollow mesoporous carbon nano-sphere as a container and a lubricating oil as the core material. The lubricating oil includes at least one of polyol ester lubricating oil, ionic liquid lubricating oil, poly-α-olefin, perfluoropolyether, silicone oil, and paraffin oil.

6. A preparation method of the solid-liquid synergistic lubricating microcapsule according to any one of claims 1 - 5, the preparation method comprising the following steps: S1. Add the solid filler to the liquid lubricant and stir evenly to obtain core material A; S2. Dissolve the core material A and the shell material in an organic solvent and stir evenly to obtain an oil phase solution B; S3. Dissolve the surfactant in water and stir evenly to obtain an aqueous phase solution C; S4. Disperse the oil phase solution B into the aqueous phase solution C and stir for emulsification to volatilize the organic solvent. After the shell material precipitates, filter to obtain the solid-liquid synergistic lubricating microcapsule.

7. The preparation method of the solid-liquid synergistic lubricating microcapsule according to claim 6, characterized in that, In step S2, the mass ratio of the core material A to the shell material is (0.2 - 2):1; And / or, the organic solvent includes at least one of dichloromethane and chloroform; And / or, in step S2, the ratio of the mass of the shell material to the volume of the organic solvent is 1:(20 - 40) g / mL; And / or, the surfactant includes at least one of polyvinyl alcohol, Tween 80, sodium dodecylbenzenesulfonate, ammonium dodecyl sulfate, cetyltrimethylammonium bromide, gelatin, gum arabic, and lignin; And / or, in step S3, the ratio of the mass of the surfactant to the volume of the water is 8:(400 - 800) g / mL.

8. The preparation method of the solid-liquid synergistic lubricating microcapsule according to claim 6, wherein In step S4, the rotation speed of the stirring and emulsifying is 400 - 800 r / min, and the time of the stirring and emulsifying is 3 - 6 hours; And / or, the temperature of the stirring and emulsifying is 80% - 90% of the boiling point of the organic solvent.

9. A self-lubricating composite material, characterized in that, The self-lubricating composite material includes microcapsules and a heterophthalic polyarylether resin, and the microcapsules include the solid-liquid synergistic lubricating microcapsules described in any one of claims 1 - 5 or the solid-liquid synergistic lubricating microcapsules prepared by the preparation method described in any one of claims 6 - 8.

10. A method for preparing the self-lubricating composite material as described in claim 9, characterized in that, The preparation method includes the following steps: Mix the microcapsules and the heterophthalic polyarylether resin to obtain a mixed material; Perform a shaping process on the mixed material to obtain the self-lubricating composite material.

Images