Pasty high-temperature lubricant and preparation method thereof

Abstract

The invention relates to a pasty high-temperature lubricant and a preparation method thereof. The pasty high-temperature lubricant comprises a liquid metal lubricant and a solid lubricant phase, wherein the solid lubricant phase is MoS2 powder; and the liquid metal lubricant comprises a gallium-based liquid metal Ga-In-Sn. By adding the solid lubricating phase and utilizing a physical alloying method, the lubricating property of Ga-X liquid metal at the high temperature of 200-400 DEG C is improved; and the viscosity of the oxide of the liquid metal is fused with solid lubrication, so that the viscosity of the composite lubricant is greatly improved, the complementary advantage of solid-liquid characteristics is realized, and the high-temperature lubrication performance of the Ga-In-Sn liquid metal is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricants, in particular to a paste-like high-temperature lubricant and a preparation method thereof. Background Art

[0002] With the continuous innovation and development of industry, many high-end equipment and mechanical moving parts operate under high temperatures, high pressures, and heavy loads. The contact between various parts causes surface friction and wear, which compromises the service life and reliability of the parts. Therefore, the addition of lubricants is a key way to reduce wear failure, improve the friction properties of metal materials, improve raw material utilization, and extend the service life of equipment. Gallium is a rare metal with a metallic luster, soft texture, and high ductility. Gallium metal is a valuable resource. Semiconductor materials, electro-optical materials, new functional materials, special alloys, and organometallic compounds based on gallium metal serve as essential foundational materials for modern high-tech fields such as computers, communications, aerospace, new energy, medicine, and defense. Lubricants are a key R&D technology in the machinery manufacturing industry. Friction and wear of mechanical parts are the main cause of damage and energy loss in machinery and equipment. High-quality lubricants not only ensure the stable and accurate operation of mechanical parts, but also effectively reduce friction, achieving significant energy conservation and emission reduction, and contributing to low-carbon production. Different types and models of lubricants have different requirements. For example, while meeting the lubrication requirements, they are also required to meet certain high temperature resistance, corrosion resistance and other properties. However, there is a lack of high temperature resistant lubricants in the existing technology.

[0003] Liquid metals are a new class of functional materials that are liquid at room temperature. The most common liquid metals are mercury and gallium. Mercury's toxicity and volatility limit its development and application. Compared to mercury, gallium is non-toxic and recyclable. Gallium-based liquid metals (GLMs) exhibit high thermal conductivity, low vapor pressure, strong adhesion, excellent thermal stability, easy shearing, and good fluidity, making them promising lubricants.

[0004] In the prior art, patent CN 114621802 A proposes a gallium-based liquid metal high-temperature lubricant and a preparation method thereof. By adding metallic bismuth to achieve metal alloying, the metal viscosity and wettability are improved. The intrinsic oxide of the gallium-based liquid metal is used as an additive phase to increase the viscosity of the liquid metal, achieve a good interface between the viscosity-added phase and the alloyed liquid metal, and solve the problem of deterioration of the interface between the viscosity-added phase and the substrate at high temperatures, resulting in decreased lubrication performance. The prepared gallium-based liquid metal high-temperature lubricant achieves good lubrication performance within the range of 100 to 200°C. However, this patent only achieves improved lubrication performance stability within the range of 100 to 200°C, and has disadvantages such as complex operation and high cost.

[0005] Patent CN 114621802 A achieves metal alloying by adding bismuth metal. However, the melting point of bismuth metal is around 270°C and the density is 9.7g / cm 3 However, the mass of lubricants containing metallic bismuth is too large and can only achieve effective lubrication performance within the range of 100-200°C, failing to meet the lubrication requirements at higher temperatures. Therefore, there is an urgent need to develop a lubricant with good lubrication performance and high temperature resistance. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a preparation method and application of a paste-like high-temperature lubricant. The composite liquid metal lubricant of the present invention belongs to a high-temperature lubricant. It is obtained by adding a solid lubricating phase and rationally regulating the compounding, utilizing the complementary advantages of solid and liquid, thereby obtaining an excellent high-temperature lubricant. The present invention is doped with non-metallic inorganic materials, and the density of the inorganic material itself is less than 5g / cm 3 , and exhibits excellent anti-friction performance in the solid state at room temperature, and also has certain anti-friction performance at a high temperature of 400°C, providing new research ideas and methods for the calculation and research of friction and lubrication itself under extremely high temperature conditions.

[0007] A first object of the present invention is to provide a paste-like high-temperature lubricant comprising a liquid metal lubricant and a solid lubricant phase, wherein the solid lubricant phase is MoS2 powder. The liquid metal lubricant is a gallium-based liquid metal having the general structural formula Ga-X, where X is In, In-Sn, In-Bi, In-Zn, In-Sn-Bi, or In-Sn-Zn. Furthermore, Ga-In-Sn is preferred.

[0008] In some embodiments of the present invention, the mass ratio of the liquid metal lubricant to the solid lubricant is (100-x):x, where 10≥x≥1. Furthermore, it can be (90%-99%):(1%-10%), preferably 95:5, 90:10, etc.

[0009] In some embodiments of the present invention, the high temperature in the paste-like high-temperature lubricant refers to 200-400°C.

[0010] A second object of the present invention is to provide a method for preparing the paste-like high-temperature lubricant, comprising the following steps:

[0011] Ga and other metal raw materials X are mixed, cleaned with ultrasound and dried; then heated and cooled to room temperature to obtain gallium-based liquid metal Ga-X;

[0012] Liquid metal Ga-X and a solid lubricating phase are mixed, placed in a ceramic crucible, and manually ground until the two are fused together. The ceramic crucible is then placed in an ultrasonic cleaner for ultrasonic dispersion, and the gallium-based liquid metal and the solid lubricating phase are uniformly mixed to obtain the paste-like high-temperature lubricant.

[0013] In some embodiments of the present invention, when the gallium-based liquid metal is Ga-In-Sn, the mass percentages of the Ga, In, and Sn metal raw materials are (55-70):(32-50).

[0014] In some embodiments of the present invention, the ultrasonic cleaning agent is selected from one or more of ethanol, acetone, ethyl acetate, and petroleum ether. The ultrasonic cleaning time is 10 to 15 minutes, and the drying temperature is 55 to 85°C.

[0015] In some embodiments of the present invention, the heating temperature is 280-420° C. and the heating time is 3-5 hours.

[0016] In some embodiments of the present invention, the solid lubricating phase is a powder with particles ranging from 50 to 200 nm.

[0017] The above technical solution of the present invention has the following advantages over the prior art:

[0018] (1) The present invention improves the lubrication performance of Ga-In-Sn liquid metal at high temperatures of 200 to 400°C by adding a solid lubricating phase and utilizing a physical alloying method; by integrating the viscosity of the liquid metal oxide itself with the solid lubricating phase, the viscosity of the composite lubricant is greatly improved, achieving the complementary advantages of solid-liquid properties and further improving the high-temperature lubrication performance of Ga-In-Sn liquid metal.

[0019] (2) The present invention utilizes the layered structure of molybdenum disulfide to effectively reduce friction under high temperature conditions. The composition of the liquid lubricant will change under high temperature, and by adding MoS2, a solid lubricating film can be formed, thereby forming a certain protective layer for the metal-based liquid lubricant. Secondly, the higher melting point of MoS2 also makes it possible to provide a more lasting lubricating effect at high temperatures. MoS2 crystals are hexagonal close-packed (hexagonal closed-packed) structures, and the interlayer bonding force (van der Waals force) is much weaker than the intralayer covalent bond (S-Mo-S), so that it can slide along the base surface under the action of shear force, forming a continuous low shear strength lubricating film (the friction coefficient can be as low as 0.04), thereby reducing the friction coefficient of the lubricant as a whole, so that the metal-based lubricant can still exhibit good lubrication performance under high temperature conditions.

[0020] (3) The paste-like high-temperature lubricant prepared by the present invention has good lubrication performance in the range of 25°C to 400°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0022] Figure 1 This invention Figure 1 Schematic diagram of the friction test used in the present invention.

[0023] Figure 2 This is a friction coefficient curve of the Ga-In-Sn:MoS2=95:5 (wt%) paste lubricant in Example 1 at a high temperature of 400°C.

[0024] Figure 3 This is a friction coefficient curve of the Ga-In-Sn:MoS2=90:10 (wt%) paste lubricant in Example 1 at a high temperature of 400°C.

[0025] Figure 4 This is a friction coefficient curve of the gallium-based liquid metal in Comparative Example 1 at a high temperature of 400°C.

[0026] Reference numerals: 1 - friction upper sample pin, 2 - lubricating medium, 3 - friction lower sample disk, 4 - loading force, 5 - sliding direction. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0028] Example 1

[0029] This embodiment provides a method for preparing a Ga-In-Sn:MoS2=95:5 (wt%) paste lubricant, as shown below:

[0030] (1) Preparation method of gallium-based liquid metal

[0031] Ga, In, and Sn metal raw materials were weighed according to a mass ratio of Ga:In:Sn = 60:25:15, ultrasonically cleaned with anhydrous ethanol for 10 minutes, and dried in a drying oven at 70°C. The weighed metals were placed in a ceramic crucible and placed in a muffle furnace at 350°C. The temperature was kept at this temperature for 4 hours, and then the heating was stopped and the mixture was cooled with the furnace to room temperature to obtain gallium-based liquid metal.

[0032] (2) Preparation method of lubricant paste

[0033] The gallium-based liquid metal Ga-In-Sn:MoS2 is weighed in a ratio of 95:5 (wt%), where the particle size of MoS2 is 80-100 nm. The two are mixed and placed in a ceramic crucible and mechanically ground until the two are completely fused with each other. Then, the ceramic crucible is placed in an ultrasonic cleaner and ultrasonically dispersed for 0.5 hours. The liquid metal and solid lubricating phase are evenly mixed to obtain a paste lubricant.

[0034] Example 2

[0035] This embodiment provides a method for preparing a paste lubricant with a ratio of Ga-In-Sn:MoS2=90:10 (wt%), as shown below:

[0036] (1) Preparation method of gallium-based liquid metal

[0037] Ga, In, and Sn metal raw materials were weighed in the ratio of Ga:In:Sn = 67:20.5:12.5, ultrasonically cleaned with anhydrous ethanol for 15 minutes, and dried in a drying oven at 70°C. The weighed metals were placed in a ceramic crucible and placed in a muffle furnace at 350°C for 4 hours. The heating was stopped and the metals were cooled with the furnace to room temperature to obtain gallium-based liquid metal.

[0038] (2) Preparation method of lubricant paste

[0039] Ga-In-Sn:MoS2=90:10 (wt%) are weighed, where the particle size of MoS2 is 80-100 nm. The two are mixed and placed in a ceramic crucible and mechanically ground until the two are completely fused with each other. Then, the ceramic crucible is placed in an ultrasonic cleaner and ultrasonically dispersed for 1 hour. The liquid metal and solid lubricating phase are evenly mixed to obtain a paste lubricant.

[0040] Comparative Example 1

[0041] This comparative example provides a method for preparing liquid metal, which is specifically as follows:

[0042] Ga, In, and Sn metal raw materials were weighed according to a mass ratio of Ga:In:Sn = 60:25:15, ultrasonically cleaned with anhydrous ethanol for 10 minutes, and dried in a drying oven at 70°C. The weighed metals were placed in a ceramic crucible and placed in a muffle furnace at 350°C. The temperature was kept at this temperature for 4 hours, and then the heating was stopped and the mixture was cooled with the furnace to room temperature to obtain gallium-based liquid metal.

[0043] Performance test: friction and wear performance test experiment

[0044] The lubricating properties of the paste lubricant obtained in the embodiment of the present invention and the gallium-based liquid metal obtained in Comparative Example 1 were tested using an MMQ-02G high-temperature friction and wear testing machine.

[0045] Friction conditions: the friction pair is a pin-on-disc type, the frequency is 2 Hz, the loading load is 10 N, the friction sliding time is 1500 s, and the test temperature range is 25-400° C. The experimental results of the examples and comparative examples are shown in Table 1.

[0046] Table 1

[0047]

[0048] As can be seen from Table 1, under the same friction test conditions, the composite liquid metal lubricant in Example 1 has a friction coefficient of 0.3579 to 0.5549 in the range of 25 to 400°C; the composite liquid metal lubricant in Example 2 has a friction coefficient of 0.4165 to 0.5357 in the range of 25 to 400°C; and the liquid metal lubricant in Comparative Example 1 has a friction coefficient of 0.6558 to 0.7471 in the range of 25 to 400°C, indicating that Examples 1-2 can greatly improve the high-temperature lubrication performance of the composite liquid metal lubricant by adding solid phase molybdenum disulfide.

[0049] All the friction tests mentioned above were carried out in an argon flow environment, which means that argon was continuously introduced during the friction process at a flow rate of 10 L / min.

[0050] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A paste-like high-temperature lubricant, characterized in that: The paste-like high-temperature lubricant includes a liquid metal lubricant and a solid lubricant phase, wherein the solid lubricant phase is MoS2 powder; the liquid metal lubricant includes a gallium-based liquid metal, which is a gallium-based liquid metal with a general structural formula of Ga-X, wherein X is In, In-Sn, In-Bi, In-Zn, In-Sn-Bi or In-Sn-Zn.

2. The paste-like high-temperature lubricant according to claim 1, characterized in that: The mass ratio of the liquid metal lubricant to the solid lubricant phase is (100-x):x, where 10≥x≥1.

3. The paste-like high-temperature lubricant according to claim 1, characterized in that: The high temperature in paste-like high-temperature lubricants refers to 200-400°C.

4. A method for preparing a paste-like high-temperature lubricant according to any one of claims 1 to 3, characterized in that: The following steps are involved: Ga and metal raw material X are mixed, cleaned with ultrasound and dried; then heated and cooled to room temperature to obtain gallium-based liquid metal Ga-X; Liquid metal Ga-X and a solid lubricating phase are mixed, placed in a ceramic crucible, and manually ground until the two are fused together. The ceramic crucible is then placed in an ultrasonic cleaner for ultrasonic dispersion, and the gallium-based liquid metal and the solid lubricating phase are uniformly mixed to obtain the paste-like high-temperature lubricant.

5. The preparation method according to claim 4, characterized in that The mass percentage of Ga and X metal raw materials is (55-70):(32-50).

6. The preparation method according to claim 4, characterized in that The ultrasonic cleaning agent is selected from one or more of ethanol, acetone, ethyl acetate and petroleum ether, the ultrasonic cleaning time is 10 to 15 minutes, and the drying temperature is 55 to 85°C.

7. The preparation method according to claim 4, characterized in that The heating temperature is 280-420°C and the heating time is 3-5 hours.

8. The preparation method according to claim 4, characterized in that The solid lubricating phase is powder, and the particles are 50 to 200 nm.

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