A new type of solid lubricant (Nb x Ta 1-x )2CSe2 preparation method

Abstract

The present invention relates to the technical field of solid lubricants, in particular to a new type of solid lubricant (Nb x Ta 1‑x )2CSe2 preparation method. The method comprises the following steps: (1) weighing Nb powder, Ta powder, C powder, Se powder and polytetrafluoroethylene powder as reactants and placing them in a ball mill, adding anhydrous ethanol and ball milling for 2 to 8 hours to mix them evenly; (2) after drying, pressing the mixture into a reactant disc, and coating the surface of the reactant disc with a layer of a mixture of KCl and NaCl salt shell, and sealing the reactant disc coated with the salt shell in a quartz tube; (3) heat-treating the quartz tube enclosing the reactant disc in a tubular atmosphere furnace at a heat treatment temperature of 1000 to 1300°C and a holding time of 2 to 10 hours; after naturally cooling to room temperature, washing to remove salt, and obtaining (Nb x Ta 1‑x )2CSe2 solid lubricant. The present invention can prepare (Nb2CSe2 solid lubricant with high chemical stability and excellent lubrication effect through a simple process. x Ta 1‑x )2CSe2 solid lubricating material, suitable for harsh working conditions such as vacuum, low temperature and high temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of solid lubricants, in particular to a new type of solid lubricant (Nb x Ta 1-x )2CSe2 preparation method. Background Art

[0002] Friction and wear under extreme operating conditions, such as high and low temperatures and high vacuum, not only wastes significant energy in industrial production but can also lead to mechanical equipment failure. However, lubricants are the most effective means of reducing friction, minimizing or preventing wear, and extending the life of mechanical equipment. Lubricants are generally categorized as liquid lubricants and solid lubricants. Solid lubricants, in particular, can meet the lubrication requirements of many demanding operating conditions, including vacuum, high and low temperatures, and so on.

[0003] At present, traditional solid lubricating materials mainly include graphite, molybdenum disulfide, polytetrafluoroethylene, etc. Graphite has extremely poor lubrication performance and wear life in a vacuum environment (Ouyang JH, Li YF, Zhang YZ, et al. High-temperature solid lubricants and self-lubricating composites: A critical review [J]. Lubricants, 2022, 10 (8): 177); while molybdenum disulfide is easily oxidized and decomposed into complex oxides and acidic substances in high temperature and humid environments, resulting in a decrease in lubrication performance (Vazirisereshk MR, Martini A, Strubbe DA, et al. Solid lubrication with MoS2: a review [J]. Lubricants, 2019, 7 (7): 57); polytetrafluoroethylene is prone to cold flow under high load conditions and is not resistant to radiation (Kumar R, Banga HK, Singh H, et al. An outline on modern day applications of solid lubricants). lubricants[J].MaterialsToday:Proceedings,2020,28:1962-1967.), therefore, traditional solid lubricants are difficult to meet the requirements of use under extreme working conditions, and it is particularly urgent to develop new solid lubricants for use under harsh conditions.

[0004] A document (Li Changsheng et al., Research on the Friction and Wear Properties of Nano-NbSe2-Cu Composite Materials [J]. Mining Engineering, 2008, 28:79-82) prepares NbSe2 nanomaterials with excellent friction properties. However, the preparation method has high equipment requirements and low output, which limits its industrial production. A patent (A method for preparing a fluorinated graphite solid lubricant) prepares fluorinated graphite with excellent lubricity by treating a mixture of graphite and a fluorine source in fluorine gas. Expandable graphite, octafluoropentanol, and a fluorinated surfactant are dissolved in a mixed solvent of deionized water and ethylene glycol, ultrasonically emulsified, transferred to a high-pressure reactor for heat treatment, and finally subjected to high-temperature heat treatment in fluorine gas to obtain fluorinated graphite with excellent friction properties. This method uses relatively dangerous fluorine gas, has a long heat treatment time, and has low production efficiency, making it unsuitable for large-scale industrial production.

[0005] Layered (Nb x Ta 1-x )2CSe2 is a metallic material formed by atomic covalent bonds of Se-Nb / Ta-C, and its structure is similar to that of graphite. (Nb x Ta 1-x )2CSe2 layers are bound by van der Waals forces and can slip, which theoretically makes (Nb x Ta 1-x )2CSe2 has a lower friction coefficient, while (Nb x Ta 1-x )2CSe2 has the advantages of excellent thermal stability, making (Nb x Ta 1-x )2CSe2 has potential applications in the field of solid lubricants. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention provides a new type of solid lubricant (Nb x Ta 1-x )2CSe2 preparation method, through a simple process, can prepare a solid lubricating material with high chemical stability and excellent lubrication effect, which has potential application prospects under harsh working conditions such as high temperature and low temperature.

[0007] The technical solution of the present invention is:

[0008] A new type of solid lubricant (Nb x Ta 1-x )2CSe2 preparation method, comprising the following steps:

[0009] (1) Weigh Nb powder, Ta powder, C powder, Se powder and polytetrafluoroethylene powder as reactants and place them in a ball mill. The molar ratio of Nb powder, Ta powder, C powder, Se powder and polytetrafluoroethylene powder is (0-2.2):(0-2.2):(0.85-1.2):(1.85-2.5):(0-0.01). Add anhydrous ethanol and ball mill for 2-8 hours to mix uniformly.

[0010] (2) After drying, the mixture is pressed into a reactant disc, and a layer of a mixture of KCl and NaCl salt shell is coated on the surface of the reactant disc, and the reactant disc coated with the salt shell is sealed in a quartz tube;

[0011] (3) The quartz tube sealed with the reactant disc is heat-treated in a tubular atmosphere furnace at a temperature of 1000-1300°C for 2-10 hours; after cooling naturally to room temperature, the salt is washed to obtain (Nb x Ta 1-x )2CSe2 solid lubricant.

[0012] The solid lubricant (Nb x Ta 1-x )2CSe2 preparation method, in step (1), the molar ratio of Nb powder and Ta powder to anhydrous ethanol is 1: (0.05~0.1).

[0013] The solid lubricant (Nb x Ta 1-x )2CSe2 preparation method, in step (1), the particle sizes of Nb powder, Ta powder, C powder, Se powder and polytetrafluoroethylene powder are 5-40μm, 5-40μm, 10-60nm, 20-200μm and 100-250nm respectively.

[0014] The solid lubricant (Nb x Ta 1-x )2CSe2 preparation method, in step (2), the diameter of the pressed reactant disc is 8 to 16 mm, and the thickness of the reactant disc is 1 to 10 mm.

[0015] The solid lubricant (Nb x Ta 1-x )2CSe2 preparation method, in step (2), the mass ratio of KCl, NaCl and reactant disc is (0.5~1.5):(0.5~1.5):1.

[0016] The solid lubricant (Nb x Ta 1-x )2CSe2 preparation method, in step (3), the heat treatment adopts a protective atmosphere of a mixture of argon and hydrogen, and the volume ratio of argon and hydrogen is (95~100):(0~5).

[0017] The solid lubricant (Nb x Ta 1-x )2CSe2 preparation method, in step (3), the prepared (Nb x Ta 1-x )The grain size of 2CSe2 solid lubricant is 100~500nm and the thickness is 5~50nm.

[0018] The design concept of the present invention is:

[0019] The synthesized (Nb x Ta 1-x )2CSe2 has a typical two-dimensional layered structure. x Ta 1-x )2CSe2 layers are bound together by weak van der Waals forces, which allow the layers to slide and have a low friction coefficient; while (Nb x Ta 1-x )2CSe2 sheets are made of atomic covalent bonds Se-Nb / Ta-C, which have excellent chemical stability and high and low temperature resistance. x Ta 1-x )2CSe2 as a solid lubricant has broad application prospects under harsh working conditions such as vacuum, low temperature and high temperature.

[0020] The advantages and beneficial effects of the present invention are:

[0021] 1. The solid lubricant prepared by the present invention (Nb x Ta 1-x )2CSe2 has the advantages of weak interlayer bonding and stable intralayer bonding. Van der Waals forces bind the layers together, allowing for interlayer slip, while covalent bonds within the layers ensure high chemical stability. Furthermore, the synthesis method is simple and easy to operate, facilitating large-scale production.

[0022] 2. The solid lubricant (Nb x Ta 1-x )2CSe2 has high chemical stability and is resistant to high and low temperatures. It has broad application prospects under harsh working conditions such as vacuum, low temperature, and high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 2 is the XRD pattern of the solid lubricant Nb2CSe2 prepared in Example 1. In the figure, the abscissa 2θ represents the diffraction angle (°), and the ordinate Intensity represents the diffraction peak intensity (au).

[0024] Figure 2This is the energy spectrum of the solid lubricant Nb2CSe2 in Example 1; wherein, a is the high-angle annular dark field image of Nb2CSe2, b is the surface scan of the Nb element, c is the surface scan of the C element, and d is the surface scan of the Se element.

[0025] Figure 3 This is a scanning electron micrograph of the solid lubricant Nb2CSe2 in Example 1.

[0026] Figure 4 (a) Transmission electron micrograph and (b) selected area electron diffraction pattern of the solid lubricant Nb2CSe2 in Example 1.

[0027] Figure 5 This is a high-angle annular dark field image of the solid lubricant Nb2CSe2 at the atomic scale in Example 1.

[0028] Figure 6 The present invention compares the interlayer peeling energy of traditional solid lubricants (graphite, MoS2) and Nb2CSe2, where the vertical axis Binding energy represents the binding energy (J / m 2 ).

[0029] Figure 7 This is the friction coefficient test curve of the solid lubricant Nb2CSe2 in Example 1.

[0030] Figure 8 2 is the XRD pattern of the solid lubricant Ta2CSe2 prepared in Example 2; in the figure, the abscissa 2θ represents the diffraction angle (°), and the ordinate Intensity represents the diffraction peak intensity (au).

[0031] Figure 9 This is the energy spectrum of the solid lubricant Ta2CSe2 in Example 1; wherein, a is the high-angle annular dark field image of Ta2CSe2, b is the surface scan of the Ta element, c is the surface scan of the C element, and d is the surface scan of the Se element.

[0032] Figure 10 The solid lubricant (Ta 0.5 Nb 0.5 )2CSe2 XRD pattern; in the figure, the horizontal axis 2θ represents the diffraction angle (°), and the vertical axis Intensity represents the diffraction peak intensity (au).

[0033] Figure 11 is the solid lubricant (Ta 0.5 Nb 0.5 )Scanning electron micrograph of 2CSe2. DETAILED DESCRIPTION

[0034] In the specific implementation process, the present invention proposes a new type of solid lubricant (Nb x Ta 1-x )2CSe2 preparation method, comprising the following steps: (1) niobium powder (Nb), tantalum powder (Ta), carbon powder (C), selenium powder (Se) and polytetrafluoroethylene powder (PTFE) and other reactants are mixed uniformly by ball milling, and then a reactant disc coated with a salt shell (sodium chloride and potassium chloride) is pressed; (2) the reactant disc coated with the salt shell is heat-treated in a tubular atmosphere furnace, cooled naturally to room temperature, and sodium chloride and potassium chloride are removed to obtain a new solid lubricant powder (Nb x Ta 1-x )2CSe2, preferably x=0~1. The solid lubricant prepared by this method (Nb x Ta 1-x )2CSe2 has high chemical stability, and its preparation process is simple and fast, making it easy to commercialize.

[0035] In order to make the contents of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. However, the following embodiments are merely simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0036] The feasibility of the present invention is further verified by examples below.

[0037] Example 1

[0038] In this embodiment, the specific steps of the preparation method of a new type of solid lubricant Nb2CSe2 are as follows:

[0039] (1) 9.3 g of Nb powder, 0.6 g of C powder, 7.9 g of Se powder, and 0.67 g of polytetrafluoroethylene powder were weighed as reactants, with the particle sizes of Nb powder, C powder, Se powder, and polytetrafluoroethylene powder being 40 μm, 20 nm, 200 μm, and 200 nm, respectively. The reactants were placed in a ball mill, and 10 mL of anhydrous ethanol was added and ball milled for 4 h. After drying, 1 g of the reactants was weighed and pressed into a reactant disc with a diameter of 10 mm and a thickness of 1 mm. A layer of salt shell was then coated on the surface of the reactant disc. A mixture of NaCl and KCl was used as the salt shell, with a mass ratio of NaCl to KCl of 1:1 and a mass ratio of the salt shell to the reactant of 1:1. Finally, the reactant disc coated with the salt shell was sealed in a quartz tube.

[0040] (2) The quartz tube containing the reactant disc was placed in a tube furnace for heat treatment under an Ar / H2 (100 Vol.% + 0 Vol.%) protective atmosphere at 1250°C for 6 hours. After naturally cooling to room temperature, the solid lubricant Nb2CSe2 was washed to remove the salt. The prepared Nb2CSe2 solid lubricant had a grain size of 200 nm and a thickness of 20 nm.

[0041] like Figure 1 As shown in the figure, the XRD patterns of Nb2CSe2 are the experimental data and the theoretical simulation data respectively. The comparison confirms that the experimental data of Nb2CSe2 are consistent with the theoretical simulation, indicating that pure phase Nb2CSe2 has been prepared.

[0042] like Figure 2 As shown in a, it can be seen from the high-angle annular dark field image of Nb2CSe2 that Nb2CSe2 is a regular hexagonal shape. Figure 2 As shown in bd, it can be seen from the surface scan of Nb, C, and Se elements of Nb2CSe2 that the above three elements are evenly distributed on the hexagonal flakes of Nb2CSe2, which also confirms that Nb2CSe2 has been synthesized;

[0043] like Figure 3 As shown, the synthesized Nb2CSe2 samples are all two-dimensional flake structures, most of which are hexagonal in shape, and a few are long strips;

[0044] like Figure 4 As shown in a, from the transmission electron micrograph of Nb2CSe2, an obvious layered structure can be observed; Figure 4 As shown in b, obvious diffraction spots can be seen from the selected area electron diffraction, indicating that the synthesized Nb2CSe2 sample has high crystallinity;

[0045] like Figure 5 The figure shows a high-angle annular dark field image of Nb2CSe2 with atomic resolution, which shows the distribution of Nb2CSe2 atoms. They are arranged in the form of Se-Nb-C-Nb-Se, and the layers are bonded by van der Waals forces, indicating that the bonding within the layer is stable.

[0046] like Figure 6 As shown in Figure 3, the interlayer bonding strength of traditional solid lubricants graphite, MoS2 and Nb2CSe2 was compared, and it was found that the interlayer bonding energy of these materials is comparable, and the interlayer bonding of Nb2CSe2 is slightly stronger, indicating that Nb2CSe2 is also suitable as a solid lubricant.

[0047] like Figure 7 As shown in Figure 2, we tested the friction coefficient of Nb2CSe2 and found that the friction coefficient of this material is only 0.175, which is significantly lower than that of traditional solid lubricant graphite (the friction coefficient of graphite is 0.23).

[0048] Example 2

[0049] In this embodiment, the specific steps of the preparation method of a new type of solid lubricant Ta2CSe2 are as follows:

[0050] The only difference from Example 1 is that 18.1 g Ta powder, 7.9 g Se powder, 0.6 g C powder, and polytetrafluoroethylene powder are weighed as reactants, and the particle sizes of Ta powder, C powder, Se powder, and polytetrafluoroethylene powder are 40 μm, 20 nm, 200 μm, and 200 nm, respectively. Other than that, the method steps are the same, and a pure phase Ta2CSe2 solid lubricant can be obtained, such as Figure 8 The prepared Ta2CSe2 solid lubricant grains are regular flakes with a grain size of about 300nm and a thickness of 25nm. Figure 9 shown.

[0051] Example 3

[0052] In this embodiment, a new type of solid lubricant (Nb 0.5 Ta 0.5 )2CSe2 preparation method specific steps are as follows:

[0053] The only difference from Example 1 is that 9.1g Ta powder, 4.7g Nb powder, 7.9g Se powder, 0.6g C powder and polytetrafluoroethylene powder are weighed as reactants. The particle sizes of Nb powder, Ta powder, C powder, Se powder and polytetrafluoroethylene powder are 40μm, 40μm, 20μm, 200μm and 200nm respectively. After heat treatment and natural cooling to room temperature, the solid lubricant (Nb 0.5 Ta 0.5 )2CSe2. Figure 10 As shown, pure phase (Nb 0.5 Ta 0.5 )2CSe2 solid lubricant, its grain size is about 200nm, thickness is about 10nm, such as Figure 11 shown.

[0054] Example 4

[0055] In this embodiment, the specific steps of the preparation method of a new type of solid lubricant Nb2CSe2 are as follows:

[0056] The only difference from Example 1 is that a mixture of NaCl and KCl is used as the salt shell, with a mass ratio of NaCl to KCl of 2:1, and a mass ratio of the salt shell to the reactants of 1:2. Finally, the salt shell-coated reactant disc is sealed in a quartz tube. In this example, the Nb2CSe2 solid lubricant prepared has a grain size of 300 nm and a thickness of 20 nm.

[0057] The results of the examples show that the new solid lubricant (Nb x Ta 1-x )2CSe2 preparation method is simple, fast and low cost, and (Nb x Ta 1-x )2CSe2 has a typical layered structure. The layers are bonded by van der Waals forces and can slip. The layers are bonded by Se-Nb / Ta-C-Nb / Ta-Se covalent bonds, which makes the layers have high chemical stability. Therefore, (Nb x Ta 1-x )2CSe2 has potential applications as a solid lubricant in harsh working conditions such as vacuum, low temperature, and high temperature. The present invention is applicable to a variety of lubrication fields, including lubricant additives and solid lubricant coatings, and has broad application prospects in the field of solid lubrication technology.

[0058] The above description is only a preferred embodiment of the present invention, but the implementation of the present invention is not limited to the above embodiment. Any obvious improvements, replacements, or modifications made by those skilled in the art on the basis of the present invention fall within the scope of protection of the present invention.

Claims

1. A type of solid lubricant (Nb x Ta 1-x )2CSe2 preparation method, characterized in that, The steps include: (1) Weigh Nb powder, Ta powder, C powder, Se powder, and polytetrafluoroethylene powder as reactants and place them in a ball mill. The molar ratio of Nb powder, Ta powder, C powder, Se powder, and polytetrafluoroethylene powder is (0-2.2): (0-2.2): (0.85-1.2): (1.85-2.5): (0-0.01). Add anhydrous ethanol and ball mill for 2-8 h to mix well. (2) After drying, the mixture is pressed into a reactant disc, and a layer of salt shell of a mixture of KCl and NaCl is coated on the surface of the reactant disc, and the reactant disc coated with the salt shell is sealed in a quartz tube; (3) The quartz tube sealed with the reactant disc is heat-treated in a tubular atmosphere furnace at a temperature of 1000-1300°C for 2-10 h; after cooling naturally to room temperature, the salt is removed by washing to obtain (Nb x Ta 1-x )2CSe2 solid lubricant.

2. The solid lubricant (Nb) according to claim 1 x Ta 1-x )2CSe2 preparation method, characterized in that, In step (1), the molar ratio of Nb powder and Ta powder to anhydrous ethanol is 1:(0.05~0.1).

3. The solid lubricant (Nb) according to claim 1 x Ta 1-x )2CSe2 preparation method, characterized in that, In step (1), the particle sizes of Nb powder, Ta powder, C powder, Se powder and polytetrafluoroethylene powder are 5~40 μm, 5~40 μm, 10~60 nm, 20~200 μm and 100~250 nm, respectively.

4. The solid lubricant (Nb) according to claim 1 x Ta 1-x )2CSe2 preparation method, characterized in that, In step (2), the diameter of the pressed reactant disc is 8 to 16 mm, and the thickness of the reactant disc is 1 to 10 mm.

5. The solid lubricant (Nb) according to claim 1 x Ta 1-x )2CSe2 preparation method, characterized in that, In step (2), the mass ratio of KCl, NaCl and reactant disc is (0.5~1.5):(0.5~1.5):

1.

6. The solid lubricant (Nb) according to claim 1 x Ta 1-x )2CSe2 preparation method, characterized in that, In step (3), the heat treatment adopts a protective atmosphere of a mixture of argon and hydrogen, and the volume ratio of argon to hydrogen is (95~100): (0~5).

7. The solid lubricant (Nb) according to claim 1 x Ta 1-x )2CSe2 preparation method, characterized in that, In step (3), the prepared (Nb x Ta 1-x )2CSe2 solid lubricant has a grain size of 100~500 nm and a thickness of 5~50 nm.

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