阅读说明：本技术 一种高分散无定形碳包覆六方氮化硼纳米片及其制备方法 (High-dispersion amorphous carbon coated hexagonal boron nitride nanosheet and preparation method thereof ) 是由 宋浩杰 张远超 杨进 贾晓华 王思哲 李永 于 2020-12-23 设计创作，主要内容包括：本发明公开一种高分散无定形碳包覆六方氮化硼纳米片及其制备方法,制备方法包括步骤1)按质量比为1：(5～15)的六方氮化硼粉末和糖均匀混合,球磨得到混合粉体；2)将混合粉体分散在水中经超声、离心处理取离心产物得到糖接枝氮化硼纳米片；3)将糖接枝氮化硼纳米片放入反应釜中以2～4℃/min升温速率升温至180～220℃,保温2～6h,即得到高分散无定形碳包覆的六方氮化硼纳米片；本发明通过球磨工艺和超声法在氮化硼表面接枝糖,其反应过程简单、不需要大型的设备,糖在球磨过程中充当表面改性物质,在水热碳化过程中充当碳源使得氮化硼表面包覆一层水热碳层提高其在水中的分散稳定性。(The invention discloses a high-dispersion amorphous carbon-coated hexagonal boron nitride nanosheet and a preparation method thereof, wherein the preparation method comprises the following steps of 1) by mass: (5-15) uniformly mixing the hexagonal boron nitride powder and sugar, and performing ball milling to obtain mixed powder; 2) dispersing the mixed powder in water, and performing ultrasonic and centrifugal treatment to obtain a centrifugal product to obtain a sugar grafted boron nitride nanosheet; 3) putting the sugar grafted boron nitride nanosheets into a reaction kettle, heating to 180-220 ℃ at a heating rate of 2-4 ℃/min, and preserving heat for 2-6 hours to obtain highly dispersed amorphous carbon coated hexagonal boron nitride nanosheets; the sugar is grafted on the surface of the boron nitride through a ball milling process and an ultrasonic method, the reaction process is simple, large-scale equipment is not needed, the sugar serves as a surface modification substance in the ball milling process, and serves as a carbon source in the hydrothermal carbonization process, so that the surface of the boron nitride is coated with a hydrothermal carbon layer to improve the dispersion stability of the boron nitride in water.)

1. A preparation method of a high-dispersion amorphous carbon-coated hexagonal boron nitride nanosheet is characterized by comprising the following steps: the method specifically comprises the following steps:

step 1: uniformly mixing hexagonal boron nitride powder and sugar according to the mass ratio of 1: 5-15, and performing ball milling to obtain mixed powder;

step 2: dispersing the mixed powder in water, and performing ultrasonic and centrifugal treatment to obtain a centrifugal product to obtain a sugar grafted boron nitride nanosheet;

and step 3: and (3) putting the sugar grafted boron nitride nanosheets into a reaction kettle, heating to 180-220 ℃ at a heating rate of 2-4 ℃/min, and preserving heat for 2-6 hours to obtain the high-dispersion amorphous carbon coated hexagonal boron nitride nanosheets.

2. The preparation method of the highly dispersed amorphous carbon coated hexagonal boron nitride nanosheet according to claim 1, wherein: the diameter of the hexagonal boron nitride powder in the step 1 is 20-30 μm.

3. The preparation method of the highly dispersed amorphous carbon coated hexagonal boron nitride nanosheet according to claim 1, wherein: the sugar in the step 1 is sucrose, fructose, glucose, honey, starch or cellulose.

4. The preparation method of the highly dispersed amorphous carbon coated hexagonal boron nitride nanosheet according to claim 1, wherein: the ball milling speed in the step 1 is 400-700 rpm, and the ball milling time is 8-16 h.

5. The preparation method of the highly dispersed amorphous carbon coated hexagonal boron nitride nanosheet according to claim 1, wherein: the ultrasonic power in the step 2 is 100-500W, and the ultrasonic time is 1-2 h.

6. The preparation method of the highly dispersed amorphous carbon coated hexagonal boron nitride nanosheet according to claim 5, wherein: the centrifugation speed in the step 2 is 3000-8000 rpm, and the centrifugation time is 15-30 min.

7. Highly dispersed amorphous carbon-coated hexagonal boron nitride nanoplates prepared according to the preparation method of any one of claims 1-6.

Technical Field

The invention relates to a boron nitride nanosheet, in particular to a high-dispersion amorphous carbon-coated hexagonal boron nitride nanosheet and a preparation method thereof.

Background

Boron nitride of "white graphene" hereinafter abbreviated as h-BN is a two-dimensional layered nanomaterial having high insulation, thermal stability, strong oxidation resistance and corrosion resistance. However, strong van de Waals acting force and acting force with local ionic bond property exist between the BN atomic layers in the BN atomic layer, so that the BN atomic layer is difficult to peel off, and only the BN atomic layerThe interlayer distance of (A) is easy to agglomerate, so that the solubility of h-BN in polar solvents such as organic solvents or water is limited.

The preparation method of h-BN is divided into a top-down ball milling method, a fluid method, a liquid phase stripping method, an ion intercalation method, a bottom-up chemical vapor deposition method and an epitaxial growth method. However, the "bottom-up" method has high requirements for experimental equipment, requires high temperature and high pressure for reaction, has high energy consumption, greatly increases production cost, and has more limitations for subsequent applications. Therefore, the ball milling method and the liquid phase method are mostly selected as the preparation method of h-BN.

The chinese patent document CN106554514A discloses a method for preparing boron nitride nanosheets by a mechanical method, which has complex steps and requires an alkaline solution to perform a modification process on the boron nitride surface at a later stage.

Chinese patent document CN104803363A discloses that hexagonal boron nitride powder is mixed with a polar organic solvent such as dodecyl pyrrolidone, isopropyl alcohol, N-methyl pyrrolidone, dimethyl formamide, N-methyl formamide, etc. in a certain proportion, and then the mixture is sheared and peeled by a high shear dispersion emulsifier under a certain temperature, shearing speed and shearing time.

The Chinese patent document CN104803363A discloses a method for preparing hexagonal boron nitride nanosheets by using intercalation and a surfactant through ultrasonic and hydrothermal reactions, wherein a dispersion prepared by the method is obviously precipitated after standing for one week, and a polar organic solvent mentioned in CN104803363A is required in the later period, is difficult to remove and harmful to a human body, causes pollution to the environment, and increases the post-treatment steps of experiments.

Disclosure of Invention

The invention aims to provide an amorphous carbon-coated hexagonal boron nitride nanosheet and a preparation method thereof, wherein the amorphous carbon-coated hexagonal boron nitride nanosheet is simple in preparation process, low in cost and environment-friendly, and has good dispersibility and lubricating and antifriction effects in water.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of a high-dispersion amorphous carbon-coated hexagonal boron nitride nanosheet specifically comprises the following steps:

step 1: according to the mass ratio of 1: (5-15) uniformly mixing the hexagonal boron nitride powder and sugar, and performing ball milling to obtain mixed powder;

step 2: dispersing the mixed powder in water, performing ultrasonic and centrifugal treatment, and taking a centrifugal product to obtain a sugar grafted hexagonal boron nitride nanosheet;

and step 3: heating the sugar grafted hexagonal boron nitride nanosheet to 180-220 ℃ at a heating rate of 2-4 ℃/min, and preserving heat for 2-6 hours to obtain the highly dispersed amorphous carbon coated hexagonal boron nitride nanosheet.

Further, the diameter of the hexagonal boron nitride powder in the step 1 is 20-30 μm.

Further, the sugar in the step 1 is sucrose, fructose, glucose, honey, starch or cellulose.

Further, the ball milling speed in the step 1 is 400-700 rpm, and the ball milling time is 8-16 h.

Further, the ultrasonic power in the step 2 is 100-500W, and the ultrasonic time is 1-2 h.

Further, the centrifugation speed in the step 2 is 3000-8000 rpm, and the centrifugation time is 15-30 min.

A highly dispersed amorphous carbon coated hexagonal boron nitride nanosheet prepared according to the preparation method.

Compared with the prior art, the invention has the beneficial effects that:

1) according to the invention, sugar is grafted on the surfaces of the hexagonal boron nitride nanosheets by a ball milling process and an ultrasonic method, and the amorphous carbon-coated hexagonal boron nitride nanosheets with good dispersibility in water and excellent lubricating and antifriction effects are prepared after hydrothermal carbonization treatment is carried out by synergistically regulating and controlling the carbonization temperature and time, so that the preparation method is simple in operation steps, does not need large experimental equipment, and reduces the preparation cost;

2) in the preparation process, sugar serves as a surface modification substance in the ball milling process and serves as a carbon source in the hydrothermal carbonization process, so that a hydrothermal carbon layer is coated on the surface of the prepared hexagonal boron nitride nanosheet, and the dispersion stability of the hexagonal boron nitride nanosheet in water is improved; the problems that the lubricating performance of the boron nitride nanosheet is reduced due to the breakage of the grafted long molecular chain in the friction process, and the boron nitride nanosheet dispersion liquid is agglomerated in the friction process are solved;

3) according to the amorphous carbon-coated hexagonal boron nitride nanosheet prepared by the invention, sugar molecules are carbonized to serve as amorphous carbon, so that disordered carbon becomes ordered under the action of shearing force, the lubricating property of h-BN is improved, the amorphous carbon-coated hexagonal boron nitride nanosheet is directly used as a lubricating additive, secondary treatment is not needed, the environmental pollution is reduced, and the friction coefficient of lubricating grease is greatly reduced.

Drawings

FIG. 1 is a schematic representation of the present invention for preparing a modified exfoliated hexagonal boron nitride dispersion;

FIG. 2 is a schematic representation of an amorphous carbon coated hexagonal boron nitride nanosheet dispersion prepared in accordance with the present invention;

FIG. 3 is a schematic diagram showing no delamination of BN atomic layer after the dispersion liquid of amorphous carbon-coated hexagonal boron nitride nanosheets prepared according to the present invention is uniformly dispersed for 45 days;

FIG. 4 is an SEM image of amorphous carbon coated hexagonal boron nitride nanoplates made by the present invention;

FIG. 5 is an XRD pattern of amorphous carbon coated hexagonal boron nitride nanoplates prepared in accordance with the present invention;

FIG. 6 is a graph of a frictional wear test of an amorphous carbon-coated hexagonal boron nitride nanosheet prepared according to the present invention and a control.

Detailed Description

The present invention will be described in further detail with reference to the following examples, which are not intended to limit the invention thereto.

Example 1:

1) uniformly mixing commercial hexagonal boron nitride with the particle size of 20-30 mu m and cane sugar according to the mass ratio of 1: 7.

2) And ball-milling the uniformly mixed hexagonal boron nitride and sucrose for 6 hours in a planetary ball mill with the ball-milling speed of 400-700 rpm, wherein the finally obtained ball-milled mixed powder is beige.

3) And dispersing the mixed powder into water for ultrasonic treatment for 2 hours, centrifuging the ultrasonic hexagonal boron nitride dispersion liquid at 6000rpm for 20min, and taking supernatant.

4) And (3) carrying out hydrothermal carbonization on the centrifuged supernatant, wherein the hydrothermal temperature is 180 ℃, the heating rate is 2 ℃/min, the heat preservation time is 2h, naturally cooling to room temperature after the hydrothermal reaction is finished, then taking out the product after the reaction, and carrying out ultrasonic dispersion again to obtain the high-dispersion amorphous carbon-coated hexagonal boron nitride nanosheet.

Example 2:

1) uniformly mixing commercial hexagonal boron nitride with the particle size of 20-30 mu m and glucose according to the mass ratio of 1: 7.

2) And ball-milling the uniformly mixed hexagonal boron nitride and glucose for 16 hours in a planetary ball mill with the ball-milling speed of 400-700 rpm, wherein the finally obtained ball-milled mixed powder is beige.

3) And dispersing the mixed powder into water for ultrasonic treatment for 2 hours, centrifuging the ultrasonic hexagonal boron nitride dispersion liquid at 6000rpm for 20min, and taking supernatant.

4) And (3) carrying out hydrothermal carbonization on the centrifuged supernatant, wherein the hydrothermal temperature is 180 ℃, the heating rate is 2 ℃/min, the heat preservation time is 4h, naturally cooling to room temperature after the hydrothermal reaction is finished, then taking out the product after the reaction, and carrying out ultrasonic dispersion again to obtain the amorphous carbon coated hexagonal boron nitride nanosheet.

Example 3:

11) uniformly mixing commercial hexagonal boron nitride with the particle size of 20-30 mu m with fructose according to the mass ratio of 1: 7.

2) And ball-milling the uniformly mixed hexagonal boron nitride and fructose in a planetary ball mill with the ball-milling speed of 400-700 rpm for 16 hours to finally obtain the ball-milled mixed powder in beige color.

3) And dispersing the mixed powder into water for ultrasonic treatment for 2 hours, centrifuging the ultrasonic hexagonal boron nitride dispersion liquid at 6000rpm for 20min, and taking supernatant.

4) And (3) carrying out hydrothermal carbonization on the centrifuged supernatant, wherein the hydrothermal temperature is 190 ℃, the heating rate is 2 ℃/min, the heat preservation time is 2h, naturally cooling to room temperature after the hydrothermal reaction is finished, then taking out the product after the reaction, and carrying out ultrasonic dispersion again to obtain the amorphous carbon coated hexagonal boron nitride nanosheet.

Example 4:

1) uniformly mixing commercial hexagonal boron nitride with the particle size of 20-30 mu m with starch according to the mass ratio of 1: 7.

2) And ball-milling the uniformly mixed hexagonal boron nitride and starch for 16 hours in a planetary ball mill with the ball-milling speed of 400-700 rpm, wherein the finally obtained ball-milled mixed powder is beige.

3) And dispersing the mixed powder into water for ultrasonic treatment for 2 hours, centrifuging the ultrasonic hexagonal boron nitride dispersion liquid at 6000rpm for 20min, and taking supernatant.

4) And (3) carrying out hydrothermal carbonization on the centrifuged supernatant, wherein the hydrothermal temperature is 190 ℃, the heating rate is 2 ℃/min, the heat preservation time is 4h, naturally cooling to room temperature after the hydrothermal reaction is finished, then taking out the product after the reaction, and carrying out ultrasonic dispersion again to obtain the amorphous carbon coated hexagonal boron nitride nanosheet.

Example 5:

1) uniformly mixing commercial hexagonal boron nitride with the particle size of 20-30 mu m with honey according to the mass ratio of 1: 7.

2) And ball-milling the uniformly mixed hexagonal boron nitride and the honey for 16 hours in a planetary ball mill with the ball-milling speed of 400-700 rpm, wherein the finally obtained ball-milled mixed powder is beige.

3) And dispersing the mixed powder into water for ultrasonic treatment for 2 hours, centrifuging the ultrasonic hexagonal boron nitride dispersion liquid at 6000rpm for 20min, and taking supernatant.

4) And (3) carrying out hydrothermal carbonization on the centrifuged supernatant, wherein the hydrothermal temperature is 210 ℃, the heating rate is 2 ℃/min, the heat preservation time is 2h, naturally cooling to room temperature after the hydrothermal reaction is finished, then taking out the product after the reaction, and carrying out ultrasonic dispersion again to obtain the amorphous carbon coated hexagonal boron nitride nanosheet.

Example 6:

1) uniformly mixing commercial hexagonal boron nitride with the particle size of 20-30 mu m with cellulose according to the mass ratio of 1: 7.

2) And ball-milling the uniformly mixed hexagonal boron nitride and cellulose for 16 hours in a planetary ball mill with the ball-milling speed of 400-700 rpm, wherein the finally obtained ball-milled mixed powder is beige.

3) And dispersing the mixed powder into water, carrying out ultrasonic treatment for 2 hours, centrifuging the ultrasonic hexagonal boron nitride nanosheet dispersion liquid at 6000rpm for 20min, and taking supernatant.

4) And (3) carrying out hydrothermal carbonization on the centrifuged supernatant, wherein the hydrothermal temperature is 210 ℃, the heating rate is 2 ℃/min, the heat preservation time is 4h, naturally cooling to room temperature after the hydrothermal reaction is finished, then taking out the product after the reaction, and carrying out ultrasonic dispersion again to obtain the amorphous carbon coated hexagonal boron nitride nanosheet.

In summary, the modified hexagonal boron nitride dispersions obtained in examples 1-6 are shown in FIG. 1.

The amorphous carbon-coated hexagonal boron nitride nanosheet dispersion prepared in the examples 1-6 is shown in fig. 2, and the BN atomic layer is free of delamination after being uniformly dispersed for 45 days is shown in fig. 3.

SEM images of the amorphous carbon-coated hexagonal boron nitride nanosheets prepared in the examples 1-6 are shown in FIG. 4, wherein BN atom lamellae are thin and have no agglomeration, and the carbonized lamellae are obviously black.

The XRD patterns of the amorphous carbon-coated hexagonal boron nitride nanosheets prepared in examples 1-6 are shown in fig. 5, and the characteristic peaks of the XRD curves of pure boron nitride are almost negligible in slight shift at the position of 26 ℃ due to the ionic bond characteristics of hexagonal boron nitride. And the sugar was successfully grafted onto the hexagonal boron nitride sheet by comparison with the sugar curve.

The friction and wear experimental curve graphs of the amorphous carbon-coated hexagonal boron nitride nanosheets prepared in the embodiments 1-6 and the three control groups are shown in fig. 6, and the amorphous carbon-coated hexagonal boron nitride nanosheets have friction coefficients respectively reduced by 88%, 83% and 79% compared with the three control groups. The water dispersion of the hexagonal boron nitride nanosheet coated with amorphous carbon has a good lubricating effect.

Example 7:

step 1: taking 20-30 mu m hexagonal boron nitride powder and sucrose according to a mass ratio of 1: 5, and then ball-milling for 8 hours by a planetary ball mill with the ball-milling speed of 400-700 rpm to obtain beige mixed powder.

Step 2: taking out the beige mixed powder, dispersing the beige mixed powder in water, putting the beige mixed powder into a cell disruption ultrasonic instrument with the ultrasonic power of 100-500W for ultrasonic treatment for 1 hour, and centrifuging the mixture for 15min at 3000-8000 rpm after the ultrasonic treatment to obtain the sugar-grafted hexagonal boron nitride nanosheet.

And step 3: and (3) putting the sugar grafted hexagonal boron nitride nanosheets into a polytetrafluoroethylene reaction kettle, heating to 180 ℃ at a speed of 4 ℃/min for hydrothermal carbonization, keeping the temperature for 6 hours, naturally cooling to room temperature after the hydrothermal reaction is finished, taking out the reacted products, and performing ultrasonic dispersion again to obtain the high-dispersion amorphous carbon coated hexagonal boron nitride nanosheets.

Example 8:

step 1: taking 20-30 mu m hexagonal boron nitride powder and glucose according to a mass ratio of 1: 15, and then ball-milling for 12 hours by a planetary ball mill with the ball-milling speed of 400-700 rpm to obtain beige mixed powder.

Step 2: taking out the beige mixed powder, dispersing the beige mixed powder in water, putting the beige mixed powder into a cell disruption ultrasonic instrument with ultrasonic power of 100-500W for ultrasonic treatment for 1.5h, and centrifuging the mixture for 20min at 3000-8000 rpm after the ultrasonic treatment to obtain the sugar-grafted hexagonal boron nitride nanosheet.

And step 3: heating the sugar grafted hexagonal boron nitride nanosheet to 220 ℃ at a speed of 3 ℃/min in a polytetrafluoroethylene reaction kettle, carrying out hydrothermal carbonization treatment, keeping the temperature for 3h, naturally cooling to room temperature after the hydrothermal reaction is finished, taking out a product after the reaction, and carrying out ultrasonic dispersion again to obtain the high-dispersion amorphous carbon coated hexagonal boron nitride nanosheet.

Example 9:

step 1: taking 20-30 mu m hexagonal boron nitride powder and honey according to a mass ratio of 1: 11, and then ball-milling for 14 hours by a planetary ball mill with the ball-milling speed of 400-700 rpm to obtain beige mixed powder.

Step 2: taking out the beige mixed powder, dispersing the beige mixed powder in water, putting the beige mixed powder into a cell disruption ultrasonic instrument with ultrasonic power of 100-500W for ultrasonic treatment for 1 hour, and centrifuging the mixture for 24min at 3000-8000 rpm after the ultrasonic treatment to obtain the sugar-grafted hexagonal boron nitride nanosheet.

And step 3: heating the sugar grafted hexagonal boron nitride nanosheet to 210 ℃ at a speed of 3 ℃/min in a polytetrafluoroethylene reaction kettle, carrying out hydrothermal carbonization treatment, keeping the temperature for 4h, naturally cooling to room temperature after the hydrothermal reaction is finished, taking out a product after the reaction, and carrying out ultrasonic dispersion again to obtain the high-dispersion amorphous carbon coated hexagonal boron nitride nanosheet.

The present invention is described in detail with reference to the above embodiments, and those skilled in the art will understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.