Hexagonal boron nitride coated tungsten disulfide composite powder and preparation method thereof

Abstract

The invention relates to the technical field of nano composite powder materials, and provides hexagonal boron nitride coated tungsten disulfide composite powder and a preparation method thereof.The preparation method comprises the steps that hexagonal boron nitride sol is prepared through a sol-gel method, the hexagonal boron nitride sol is coated on the surface of tungsten disulfide through an in-situ adsorption gel method to form a hexagonal boron nitride precursor, and the hexagonal boron nitride precursor is prepared; and the hexagonal boron nitride precursor on the surface of the tungsten disulfide powder is sintered and converted into a compact hexagonal boron nitride coating layer through heat treatment. According to the hexagonal boron nitride coated tungsten disulfide composite powder and the preparation method thereof disclosed by the invention, hexagonal boron nitride with high chemical property stability and high temperature resistance on the outer layer can be used as a physical barrier layer, so that direct contact between external oxygen and an internal tungsten disulfide core layer is effectively isolated.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of nanocomposite powder materials, and particularly relates to a hexagonal boron nitride coated tungsten disulfide composite powder and a preparation method thereof. BACKGROUND

[0002] Tungsten disulfide (WS2) is an important layered transition metal disulfide, and the crystal structure of the tungsten disulfide is that tungsten atom layers are sandwiched between two sulfur atom layers, and the tungsten disulfide presents a unique "sandwich" layered structure. The inherent anisotropic structure endows the tungsten disulfide with excellent friction reduction performance, and the friction coefficient of the tungsten disulfide can be as low as 0.03. With the excellent performance, the tungsten disulfide is widely regarded as a high-performance solid lubricant, and is often used as a key lubricating component in composite self-lubricating materials and iron-based powder metallurgy materials to improve the tribological performance of the materials.

[0003] In modern high-performance equipment, such as engine valve seat rings and other iron-based powder metallurgy parts, the tungsten disulfide is often used as a solid lubricant additive. However, the stability of the tungsten disulfide in a high-temperature environment is a core challenge in the application of the tungsten disulfide. The initial oxidation temperature of the tungsten disulfide in an air atmosphere is 450 DEG C, and the tungsten disulfide is completely decomposed into sulfur dioxide and tungsten trioxide at 650 DEG C; in a vacuum environment, the tungsten disulfide begins to slowly decompose into sulfur and tungsten at 1100 DEG C, and the tungsten disulfide is completely decomposed at 1250 DEG C; in a hydrogen atmosphere, the tungsten disulfide reacts with hydrogen to generate hydrogen sulfide and metallic tungsten at about 80 DEG C; in a nitrogen atmosphere, the tungsten disulfide shows excellent high-temperature resistance, and the tungsten disulfide can be up to 1500 DEG C without decomposition, and the complete decomposition needs more than 2000 DEG C and the sulfur release amount is extremely low; in an argon environment, the tungsten disulfide gradually loses sulfur above 1000 DEG C. In addition, the tungsten disulfide loses lubrication at high temperatures, and the decomposition products also react with the iron-based material, affecting the overall performance of the material. Therefore, improving the high-temperature stability of the tungsten disulfide solid lubricant, preventing the failure and decomposition of the tungsten disulfide and the mutual reaction between the decomposition products and the base material have a positive significance for preparing high-performance iron-based powder metallurgy materials.

[0004] A Chinese patent with the publication number CN109174128A discloses a modification method of tungsten disulfide and application thereof, and the tungsten disulfide is treated by a mixed solution of concentrated sulfuric acid and concentrated nitric acid to obtain a green powder by using a liquid phase oxidation exfoliation method, and the green powder is mainly used for ultrasonic catalytic degradation of dye wastewater. However, the method belongs to an exfoliation type modification, and an external protective layer is not introduced, so the stability of the tungsten disulfide in a high-temperature, oxidation or friction environment cannot be effectively improved, the application scene is significantly different from the demand of the high-temperature solid lubricant, and the post-treatment cost of the strong acid waste liquid is high, which is not conducive to large-scale production.

[0005] A Chinese patent with publication number CN102836996A discloses a solid lubricating high-temperature wear-resistant powder composition and a preparation method of a composite coating thereof. A nickel-phosphorus alloy is coated on the surface of tungsten disulfide by electroless plating, forming a dense metal shell and being used for laser cladding high-temperature wear-resistant coating. However, the Ni-P layer has high hardness and no lubricity, and is easy to crack and peel off under frictional shear. The plating solution needs to be reduced by sodium hypophosphite, and the treatment of phosphorus-containing wastewater is difficult, which puts a great pressure on environmental protection.

[0006] A Chinese patent with publication number CN111850527A discloses a preparation method of copper-plated tungsten disulfide, copper-plated tungsten disulfide and its application. A metal copper coating layer is formed on the surface of tungsten disulfide powder by electroless copper plating, aiming to improve the electrical conductivity of the material and the compatibility with the metal matrix. Although it is a coating structure, the protective layer is metal copper, which has a relatively low melting point and is easy to oxidize to abrasive oxide under a friction condition higher than 500 ℃, which in turn aggravates the wear of the counterpart. In addition, the electroless plating process is complex and easy to cause non-uniformity of the coating, affecting the protection effect. These existing modification schemes either fail to provide comprehensive and durable protection or introduce new process or cost barriers, and fail to fundamentally solve the performance bottleneck of tungsten disulfide under extreme working conditions.

[0007] Therefore, how to efficiently and economically solve the decomposition problem of tungsten disulfide in a high-temperature oxidizing atmosphere to meet the urgent needs of industrial applications has become a technical problem to be solved. SUMMARY

[0008] Therefore, in order to overcome the shortcomings of the prior art, the present application aims to provide a hexagonal boron nitride coated tungsten disulfide composite powder and a preparation method thereof.

[0009] According to a first aspect of the present application, a preparation method of a hexagonal boron nitride coated tungsten disulfide composite powder is provided, which comprises: preparing a hexagonal boron nitride sol by a sol-gel method, coating the hexagonal boron nitride sol on the surface of tungsten disulfide to form a hexagonal boron nitride precursor by an in-situ adsorption gel method, and sintering the hexagonal boron nitride precursor on the surface of the tungsten disulfide powder to a dense hexagonal boron nitride coating layer by heat treatment.

[0010] Optionally, in the preparation method of the hexagonal boron nitride coated tungsten disulfide composite powder of the present application, boric acid is used as a boron source and urea is used as a nitrogen source to prepare a mixed solution, and the mixed solution with adjusted pH value is aged in a water bath to obtain the hexagonal boron nitride sol.

[0011] Optionally, in the preparation method of the hexagonal boron nitride coated tungsten disulfide composite powder of the present application, the hexagonal boron nitride sol is prepared as follows: A mixed solution A was prepared by adding 4.95 g of boric acid and 9.61 g of urea into 1000 mL of deionized water, cooling to room temperature after magnetic stirring at 300 rpm for 20 min at 65°C, and diluting with deionized water to 1000 mL; The pH value of the mixed solution A was adjusted to 8.7-9.0 with ammonia water under magnetic stirring at 200 rpm, and a hexagonal boron nitride sol was prepared by water bath aging at 60-75°C for 2-3.5 h at a stirring speed of 250-400 rpm.

[0012] Alternatively, in the method for preparing the hexagonal boron nitride coated tungsten disulfide composite powder, the tungsten disulfide suspension was added dropwise into the hexagonal boron nitride sol to prepare a mixed solution B, and the hexagonal boron nitride sol was adsorbed and gelled on the surface of the tungsten disulfide to form a hexagonal boron nitride precursor under water bath heating.

[0013] Alternatively, in the method for preparing the hexagonal boron nitride coated tungsten disulfide composite powder, the tungsten disulfide suspension was prepared by adding 0.05-0.2 g of polyvinylpyrrolidone and 0.01-0.04 g of sodium dodecylbenzenesulfonate into 450-600 mL of deionized water, magnetic stirring at a speed of 150-300 rpm for 25-40 min, adding 10 g of tungsten disulfide powder with an average particle size of 1-5 µm into the solution system in four times within the last 10 min of magnetic stirring, and ultrasonic dispersion of the solution system at a frequency of 60-60 kHz for 50-80 min after stirring to prepare the tungsten disulfide suspension.

[0014] Alternatively, in the method for preparing the hexagonal boron nitride coated tungsten disulfide composite powder, the hexagonal boron nitride precursor was formed on the surface of the tungsten disulfide as follows: The 450-600 mL of tungsten disulfide suspension was added dropwise into 1000 mL of the hexagonal boron nitride sol at 60°C to prepare a mixed solution B; The mixed solution B was magnetically stirred at a speed of 150-300 rpm for 5-8 h under a water bath at 60-75°C to prepare a coated material, and the tungsten disulfide powder coated with the hexagonal boron nitride precursor was prepared after centrifugal dispersion, washing, and drying of the coated material in sequence.

[0015] Alternatively, in the method for preparing the hexagonal boron nitride coated tungsten disulfide composite powder, after preparation of the coated material, the coated material was centrifuged at a speed of 2500-4000 rpm for 5-20 min, deionized water was added in sufficient amount after removal of the centrifugal supernatant, and the coated material was centrifuged again at a speed of 2500-4000 rpm for 5-20 min, and the precipitate was transferred to a vacuum condition at 75-90°C for drying for 10-16 h after washing and removal of impurities.

[0016] Optionally, the preparation method of the hexagonal boron nitride coated tungsten disulfide composite powder of the present application, the tungsten disulfide powder coated with the hexagonal boron nitride precursor is subjected to heat treatment in a nitrogen atmosphere, and before the heat treatment, the tungsten disulfide powder coated with the hexagonal boron nitride precursor is ground to an average particle size of 1-5 µm.

[0017] Optionally, the preparation method of the hexagonal boron nitride coated tungsten disulfide composite powder of the present application, the ground tungsten disulfide powder coated with the hexagonal boron nitride precursor is placed in a nitrogen atmosphere, heated to 970-1000 ℃ at a heating rate of 5-10 ℃ / min, and then held for 90-180 min, and then cooled to room temperature to obtain the hexagonal boron nitride coated tungsten disulfide composite powder.

[0018] According to a second aspect of the present application, a hexagonal boron nitride coated tungsten disulfide composite powder is provided, which is prepared according to the above method.

[0019] The hexagonal boron nitride coated tungsten disulfide composite powder and the preparation method thereof of the present application have the following beneficial technical effects: 1. The process is simple and economical, and a one-step sol-gel method is used, which avoids complex equipment and toxic waste liquid, meets the green environmental protection requirements, and is suitable for industrialized popularization and application.

[0020] 2. The sol-gel in-situ adsorption method is used, the pH value and temperature are adjusted, the hexagonal boron nitride precursor is nucleated, grown and gelled in-situ on the surface of the tungsten disulfide, and the problem of uneven coating caused by physical mixing is avoided.

[0021] 3. The prepared composite powder uses the highly stable and high-temperature resistant hexagonal boron nitride (h-BN) as a physical barrier layer, which effectively isolates the direct contact between external oxygen and the internal tungsten disulfide core layer. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 A flowchart of a preparation method of a hexagonal boron nitride coated tungsten disulfide composite powder according to an exemplary embodiment 1 of the present application; Figure 2 A SEM morphology diagram of a hexagonal boron nitride coated tungsten disulfide composite powder prepared according to an exemplary embodiment 3 of the present application; Figure 3An EDS pattern of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to Example 3 of the present application; Figure 4 A TEM pattern of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to Example 3 of the present application; Figure 5 An XRD pattern of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to Example 3 and Example 5 of the present application; Figure 6 A full spectrum of XPS of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to Example 5 of the present application; Figure 7 A W element fine spectrum of XPS of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to Example 5 of the present application; Figure 8 A S element fine spectrum of XPS of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to Example 5 of the present application; Figure 9 A B element fine spectrum of XPS of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to Example 5 of the present application; Figure 10 A N element fine spectrum of XPS of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to Example 5 of the present application. DETAILED DESCRIPTION

[0024] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0025] It should be noted that the following examples and features in the examples can be combined with each other without conflict unless otherwise noted; and based on the examples in the present disclosure, all other examples obtained by those of ordinary skill in the art without creative effort are within the scope of the present disclosure.

[0026] It should be noted that various aspects of the embodiments described below are within the scope of the appended claims. It should be apparent that the aspects described herein can be embodied in a wide variety of forms and that any specific structure and / or function described herein is merely illustrative. Based on the teachings herein one skilled in the art should appreciate that an aspect described herein can be implemented independently of any other aspects and that an aspect described herein can be implemented both as any claim and over multiple claims. For example, an apparatus can be implemented using any number of the aspects described herein. In addition, an apparatus can be implemented using any number of the aspects described herein in combination with one another. Example 1

[0027] Example 1 of the present application provides a preparation method of a hexagonal boron nitride coated tungsten disulfide composite powder, Figure 1 A flowchart example of the preparation method of a hexagonal boron nitride coated tungsten disulfide composite powder according to Example 1 of the present application is shown in FIG. 1. Figure 1 As shown in the figure, in this embodiment, the hexagonal boron nitride coated tungsten disulfide composite powder is prepared in the following manner: First, in this embodiment, a hexagonal boron nitride sol is prepared by a sol-gel method. As an optional example, in this embodiment, boric acid is used as a boron source and urea is used as a nitrogen source to prepare a mixed solution, and the mixed solution is aged in a water bath after pH adjustment to obtain a hexagonal boron nitride sol.

[0028] Secondly, in this embodiment, the hexagonal boron nitride sol is coated on the surface of the tungsten disulfide to form a hexagonal boron nitride precursor by in-situ adsorption gelation. As an optional example, in this embodiment, the tungsten disulfide suspension is added dropwise to the hexagonal boron nitride sol to obtain a mixed solution B, and the hexagonal boron nitride sol is adsorbed and gelled on the surface of the tungsten disulfide to form a hexagonal boron nitride precursor under water bath heating conditions.

[0029] Then, in this embodiment, the hexagonal boron nitride precursor on the surface of the tungsten disulfide powder is sintered to convert into a dense hexagonal boron nitride coating layer by heat treatment. Example 2

[0030] Step 1, preparation of a hexagonal boron nitride sol 4.95 g of boric acid and 9.61 g of urea were added to 1000 mL of deionized water, and after magnetic stirring at 300 rpm for 20 min at 65°C, the solution was cooled to room temperature. Deionized water was used to make up to 1000 mL to obtain a mixed solution A; The pH value of the mixed solution A was adjusted to 8.7 by adding ammonia under magnetic stirring at 200 rpm, and the mixed solution was aged in a water bath at 60°C under stirring at a speed of 400 rpm for 2 h to obtain a hexagonal boron nitride sol.

[0031] Step 2, preparation of tungsten disulfide powder coated with a hexagonal boron nitride precursor 0.05 g of polyvinylpyrrolidone and 0.01 g of sodium dodecylbenzenesulfonate were added to 450 mL of deionized water, and the solution was stirred at a speed of 150 rpm for 25 min. During the last 10 min of magnetic stirring, 10 g of tungsten disulfide powder with an average particle size of 1-5 µm was added to the solution system in four portions. After stirring, the solution system was ultrasonically dispersed at a frequency of 60 kHz for 50 min to obtain a tungsten disulfide suspension; The 450 mL of tungsten disulfide suspension was added dropwise to 1000 mL of the hexagonal boron nitride sol at 60°C to obtain a mixed solution B; The mixed solution B was magnetically stirred at 300 rpm for 5 h in a water bath at 75 °C to prepare a coating material. After the coating material was prepared, it was centrifuged at a speed of 2500 rpm for 20 min. After the supernatant was removed, a sufficient amount of deionized water was added, and the coating material was centrifuged again at a speed of 2500 rpm for 20 min. After washing and removing impurities, the precipitate was transferred to a vacuum dryer at 90 °C and dried for 10 h to prepare a tungsten disulfide powder coated with a hexagonal boron nitride precursor.

[0032] Step three, sintering heat treatment The tungsten disulfide powder coated with a hexagonal boron nitride precursor was ground to an average particle size of 1-5 µm. The ground tungsten disulfide powder coated with a hexagonal boron nitride precursor was heated to 970 °C at a heating rate of 5 °C / min in a nitrogen atmosphere, and then held for 180 min. After cooling to room temperature, a hexagonal boron nitride-coated tungsten disulfide composite powder was prepared. Example 3

[0033] Step one, preparation of a hexagonal boron nitride sol 4.95 g of boric acid and 9.61 g of urea were added to 1000 mL of deionized water. After being magnetically stirred at 300 rpm for 20 min at 65 °C, the solution was cooled to room temperature, and deionized water was added to make the volume 1000 mL to prepare a mixed solution A. The pH value of the mixed solution A was adjusted to 8.8 using ammonia water under magnetic stirring at 200 rpm. The solution was aged in a water bath at 65 °C for 2.5 h with stirring at a speed of 350 rpm to prepare a hexagonal boron nitride sol.

[0034] Step two, preparation of a tungsten disulfide powder coated with a hexagonal boron nitride precursor 0.1 g of polyvinylpyrrolidone and 0.02 g of sodium dodecylbenzenesulfonate were added to 500 mL of deionized water, and magnetically stirred at 200 rpm for 20 min. During the last 10 min of magnetic stirring, 10 g of tungsten disulfide powder with an average particle size of 1-5 µm was added to the solution system in four portions. After stirring, the solution system was ultrasonically dispersed at a frequency of 50 kHz for 60 min to prepare a tungsten disulfide suspension. 500 mL of the tungsten disulfide suspension was added dropwise to 1000 mL of the hexagonal boron nitride sol at 60 °C to prepare a mixed solution B. The mixed solution B was magnetically stirred at 250 rpm for 6 h under the condition of a water bath at 70 °C to prepare a coating material. After the preparation of the coating material, the coating material was centrifuged at a speed of 3000 rpm for 15 min. After removing the centrifugal supernatant, a sufficient amount of deionized water was added, and the coating material was centrifuged again at a speed of 3000 rpm for 15 min. After washing and removing the impurities, the precipitate was transferred to a vacuum condition at 85 °C and dried for 12 h to prepare a tungsten disulfide powder coated with a hexagonal boron nitride precursor on the surface.

[0035] Step three, sintering heat treatment The tungsten disulfide powder coated with a hexagonal boron nitride precursor on the surface was ground to an average particle size of 1-5 µm. The ground tungsten disulfide powder coated with a hexagonal boron nitride precursor on the surface was heated to 980 °C at a heating rate of 5 °C / min in a nitrogen atmosphere, and then held for 150 min. After cooling to room temperature, a hexagonal boron nitride-coated tungsten disulfide composite powder was prepared. Example 4

[0036] Step one, preparation of a hexagonal boron nitride sol 4.95 g of boric acid and 9.61 g of urea were added to 1000 mL of deionized water. After being magnetically stirred at 300 rpm for 20 min at 65 °C, the solution was cooled to room temperature, and deionized water was added to make the volume to 1000 mL to prepare a mixed solution A. The pH value of the mixed solution A was adjusted to 8.9 using ammonia water under magnetic stirring at 200 rpm. The solution was aged in a water bath at 70 °C for 3 h at a stirring speed of 300 rpm to prepare a hexagonal boron nitride sol.

[0037] Step two, preparation of a tungsten disulfide powder coated with a hexagonal boron nitride precursor on the surface 0.15 g of polyvinylpyrrolidone and 0.03 g of sodium dodecylbenzenesulfonate were added to 550 mL of deionized water, and magnetically stirred at 250 rpm for 15 min. During the last 10 min of magnetic stirring, 10 g of tungsten disulfide powder with an average particle size of 1-5 µm was added to the solution system in four portions. After stirring, the solution system was ultrasonically dispersed at a frequency of 40 kHz for 70 min to prepare a tungsten disulfide suspension. 550 mL of the tungsten disulfide suspension was added dropwise to 1000 mL of the hexagonal boron nitride sol at 60 °C to prepare a mixed solution B. The mixed solution B was magnetically stirred at 200 rpm for 7 h under the condition of a water bath at 65 °C to prepare a coating material. After the preparation of the coating material, the coating material was centrifuged at a speed of 3500 rpm for 10 min. After removing the centrifugal supernatant, a sufficient amount of deionized water was added, and the coating material was centrifuged again at a speed of 3500 rpm for 10 min. After washing and removing the impurities, the precipitate was transferred to a vacuum condition at 80 °C for drying for 14 h to prepare a tungsten disulfide powder coated with a hexagonal boron nitride precursor.

[0038] Step three, sintering heat treatment The tungsten disulfide powder coated with a hexagonal boron nitride precursor was ground to an average particle size of 1-5 µm. The ground tungsten disulfide powder coated with a hexagonal boron nitride precursor was heated to 990 °C at a heating rate of 10 °C / min in a nitrogen atmosphere, and then held for 120 min. After cooling to room temperature, a hexagonal boron nitride-coated tungsten disulfide composite powder was prepared. Example 5

[0039] Step one, preparation of a hexagonal boron nitride sol 4.95 g of boric acid and 9.61 g of urea were added to 1000 mL of deionized water. After magnetic stirring at 300 rpm for 20 min at 65 °C, the solution was cooled to room temperature, and deionized water was added to make the volume to 1000 mL to prepare a mixed solution A. The pH value of the mixed solution A was adjusted to 9.0 using ammonia water under magnetic stirring at 200 rpm. The solution was aged in a water bath at 75 °C for 3.5 h with stirring at a speed of 250 rpm to prepare a hexagonal boron nitride sol.

[0040] Step two, preparation of a tungsten disulfide powder coated with a hexagonal boron nitride precursor 0.2 g of polyvinylpyrrolidone and 0.04 g of sodium dodecylbenzenesulfonate were added to 600 mL of deionized water, and the solution was magnetically stirred at 250 rpm for 15 min. During the last 10 min of magnetic stirring, 10 g of tungsten disulfide powder with an average particle size of 1-5 µm was added to the solution system in four portions. After stirring, the solution system was ultrasonically dispersed at a frequency of 30 kHz for 80 min to prepare a tungsten disulfide suspension. 600 mL of the tungsten disulfide suspension was added dropwise to 1000 mL of the hexagonal boron nitride sol at 60 °C to prepare a mixed solution B. Mixed solution B was magnetically stirred at 150 rpm for 8 h in a water bath at 60℃ to obtain the coated material. After obtaining the coated material, it was centrifuged at 4000 rpm for 5 min. After removing the supernatant, sufficient deionized water was added, and the coated material was centrifuged again at 4000 rpm for 5 min. After washing and removing impurities, the precipitate was transferred to a vacuum condition at 75℃ and dried for 16 h to obtain tungsten disulfide powder with hexagonal boron nitride precursor on the surface.

[0041] Step 3: Sintering heat treatment Tungsten disulfide powder coated with hexagonal boron nitride precursor was ground to an average particle size of 1-5 µm. The ground tungsten disulfide powder coated with hexagonal boron nitride precursor was placed in a nitrogen atmosphere and heated to 1000 °C at a heating rate of 10 °C / min, held at that temperature for 90 min, and then cooled to room temperature to obtain hexagonal boron nitride coated tungsten disulfide composite powder. Example 6

[0042] The microstructure and chemical composition of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared in Example 3 of this invention were characterized using a Hitachi SU-8020 scanning electron microscope (SEM) and an energy dispersive spectroscopy (EDS) instrument. The energy dispersive spectroscopy was also analyzed at a magnification of 35,000 and a voltage of 15 kV. Figure 2 SEM image of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to exemplary embodiment 3 of the present invention; Figure 3 EDS image of hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to exemplary embodiment 3 of the present invention.

[0043] like Figure 2 and Figure 3 As shown, the hexagonal boron nitride-coated tungsten disulfide composite powder prepared in Example 3 of this invention is made from... Figure 2 It can be seen that the composite powder exhibits a regular and clear hexagonal plate-like crystal structure, with a particle size distribution between 1-3 μm, consistent with the morphological characteristics of the original tungsten disulfide powder; after high-temperature sintering, the particles still maintain good plate-like independence, with sharp edges, and no obvious melting, collapse, or severe agglomeration phenomena are observed. Figure 3 The EDS elemental distribution mapping spectrum shows that the signals of tungsten and sulfur are dense and bright, clearly defining the skeletal range of the particles. The signal points of boron and nitrogen are uniformly and diffusely covered on the particle outline determined by W and S elements, and their spatial distributions highly overlap.

[0044] The micro-morphology of the hexagonal boron nitride coated tungsten disulfide composite powder prepared in Example 3 of the present application was characterized by using a Japanese Electronics 2100F type field emission transmission electron microscope (TEM), a ZrO / W (100) Schottky thermal field emission electron gun, a magnification of 20,000 times, and an accelerating voltage of 120 kV. Figure 4 A TEM image of the hexagonal boron nitride coated tungsten disulfide composite powder prepared according to Example 3 of the present application.

[0045] As shown in Figure 4 , the hexagonal boron nitride coated tungsten disulfide composite powder prepared in Example 3 of the present application has a dark and opaque electron high-contrast feature in the core area of the image due to the strong scattering ability of tungsten atoms with high atomic number, and retains the original geometric edges and corners of the tungsten disulfide particles. In contrast, the edges and surfaces of the particles are wrapped in a thin layer of material with a lighter color and a translucent appearance, which is caused by the low atomic number of boron and nitrogen atoms and the high electron transmittance. In addition, the outer coating is not free-standing but closely adheres to the surface of the tungsten disulfide particles, forming a continuous and dense nanoscale protective shell layer that effectively improves the decomposition temperature of the tungsten disulfide material.

[0046] The phase composition of the hexagonal boron nitride coated tungsten disulfide composite powder prepared in Example 3 and Example 5 of the present application was characterized by using a Dutch Panalytical X'Pert PRO MPD type X-ray diffractometer (XRD), a scanning range of 10-90°, a further angle of 0.02°, and a scanning speed of 5° / min. Figure 5 XRD patterns of the hexagonal boron nitride coated tungsten disulfide composite powder prepared according to Example 3 and Example 5 of the present application.

[0047] As shown in Figure 5 , the XRD spectra of the hexagonal boron nitride coated tungsten disulfide composite powder prepared in Example 3 and Example 5 of the present application both have characteristic diffraction peaks that are highly consistent with the standard PDF cards of tungsten disulfide and hexagonal boron nitride, indicating that the crystal structure of tungsten disulfide is retained in the sample after high-temperature treatment, and crystalline hexagonal boron nitride phase is generated.

[0048] The elemental composition of the hexagonal boron nitride coated tungsten disulfide composite powder prepared in Example 5 of the present application was characterized by using an American Thermo Fisher ESCALAB 250Xi type X-ray photoelectron spectrometer (XPS). Figure 6 A full spectrum of XPS of the hexagonal boron nitride coated tungsten disulfide composite powder prepared according to Example 5 of the present application; Figure 7 A W element fine spectrum of XPS of the hexagonal boron nitride coated tungsten disulfide composite powder prepared according to Example 5 of the present application; Figure 8An S element fine spectrum of XPS of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to the example 5 of the present application; Figure 9 A B element fine spectrum of XPS of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to the example 5 of the present application; Figure 10 A N element fine spectrum of XPS of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared according to the example 5 of the present application.

[0049] As shown in Figures 6-10 , the XPS results of the hexagonal boron nitride-coated tungsten disulfide composite powder prepared by the example 5 of the present application show that, in the full spectrum scan, Figure 6 , the characteristic electronic peaks of W 4f, S 2p, B 1s and N 1s are detected, as well as the C 1s peak for charge correction. Figure 7 The high-resolution spectrum of W 4f shows two characteristic peaks with binding energy at about 32.5 eV and 34.6 eV, respectively, corresponding to W 4f 7 / 2 and W 4f 5 / 2 orbit, which is consistent with the valence state characteristics of W 4+ in the tungsten disulfide. Figure 8 The high-resolution spectrum of S 2p matches the characteristic binding energy of S 2- in the tungsten disulfide, and the chemical state of the tungsten disulfide phase is consistent with its inherent properties. Figure 9 , 10 The binding energy values of the two correspond to the binding energy positions of B-N chemical bond and N-B chemical bond in the hexagonal boron nitride lattice structure.

[0050] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed by the present application can be easily thought by those skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for producing a hexagonal boron nitride-coated tungsten disulfide composite powder, characterized by, The method comprises the following steps: The hexagonal boron nitride sol is prepared by a sol-gel method, the hexagonal boron nitride sol is coated on the surface of the tungsten disulfide by an in-situ adsorption gel method to form a hexagonal boron nitride precursor, and the hexagonal boron nitride precursor on the surface of the tungsten disulfide powder is sintered and converted into a dense hexagonal boron nitride coating layer by heat treatment.

2. The method of producing a hexagonal boron nitride-coated tungsten disulfide composite powder according to claim 1, characterized by, A mixed solution is prepared by using boric acid as a boron source and urea as a nitrogen source, and the mixed solution is aged in a water bath after pH value regulation to obtain the hexagonal boron nitride sol.

3. The method of producing a hexagonal boron nitride-coated tungsten disulfide composite powder according to claim 2, characterized by, The hexagonal boron nitride sol is prepared in the following manner: 4.95 g of boric acid and 9.61 g of urea are added to 1000 mL of deionized water, and after magnetic stirring at a speed of 300 rpm for 20 min at 65 ℃, the solution is cooled to room temperature, and deionized water is added to make the total volume of the solution to 1000 mL to obtain a mixed solution A; The pH value of the mixed solution A is adjusted to 8.7-9.0 by using ammonia water under magnetic stirring at a speed of 200 rpm, and the mixed solution is aged in a water bath at a stirring speed of 250-400 rpm for 2-3.5 h at 60-75 ℃ to obtain the hexagonal boron nitride sol.

4. The method of claim 1, wherein the hexagonal boron nitride-coated tungsten disulfide composite powder is prepared by the steps of: The tungsten disulfide suspension is prepared in the following manner: 0.05-0.2 g of polyvinylpyrrolidone and 0.01-0.04 g of sodium dodecylbenzenesulfonate are added to 450-600 mL of deionized water, and the solution is stirred at a speed of 150-300 rpm for 25-40 min; 10 g of tungsten disulfide powder with an average particle size of 1-5 µm is added to the solution in four portions in the last 10 min of magnetic stirring; and the solution is ultrasonically dispersed at a frequency of 60-60 kHz for 50-80 min after the stirring to obtain the tungsten disulfide suspension.

5. The method of producing a hexagonal boron nitride-coated tungsten disulfide composite powder according to claim 4, characterized by, The hexagonal boron nitride precursor is formed on the surface of the tungsten disulfide in the following manner:

6. The method of producing a hexagonal boron nitride-coated tungsten disulfide composite powder according to claim 4, characterized by, 450-600 mL of the tungsten disulfide suspension is added dropwise to 1000 mL of the hexagonal boron nitride sol at 60 ℃ to obtain a mixed solution B; The mixed solution B is magnetically stirred at a speed of 150-300 rpm for 5-8 h in a water bath at 60-75 ℃ to obtain coated material, and the coated material is centrifugally dispersed, washed and dried in sequence to obtain the tungsten disulfide powder coated with the hexagonal boron nitride precursor. After the coated material is obtained, the coated material is centrifuged at a speed of 2500-4000 rpm for 5-20 min, and after the centrifugal supernatant is removed, a sufficient amount of deionized water is added, and the coated material is centrifuged again at a speed of 2500-4000 rpm for 5-20 min; after washing and removing impurities, the precipitate is transferred to a vacuum drying oven at 75-90 ℃ and dried for 10-16 h.

7. The method of producing a hexagonal boron nitride-coated tungsten disulfide composite powder according to claim 6, characterized by, The tungsten disulfide powder coated with the hexagonal boron nitride precursor is heat-treated in a nitrogen atmosphere, and before the heat treatment, the tungsten disulfide powder coated with the hexagonal boron nitride precursor is ground to an average particle size of 1-5 µm.

8. The method of producing a hexagonal boron nitride-coated tungsten disulfide composite powder according to claim 1, characterized by, ​ 9. The method of producing a hexagonal boron nitride-coated tungsten disulfide composite powder according to claim 8, characterized by, The ground surface coated with the hexagonal boron nitride precursor of the tungsten disulfide powder is placed in a nitrogen atmosphere, heated to 970-1000℃ at a heating rate of 5-10℃ / min, and then kept for 90-180min, and cooled to room temperature to obtain the hexagonal boron nitride coated tungsten disulfide composite powder.

10. A hexagonal boron nitride-coated tungsten disulfide composite powder, characterized by, The hexagonal boron nitride coated tungsten disulfide composite powder is prepared according to the method of any one of claims 1 to 9.

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