CN117757558A

CN117757558A - Nanoscale graphite emulsion and preparation method and application thereof

Info

Publication number: CN117757558A
Application number: CN202311753080.3A
Authority: CN
Inventors: 夏莉红; 廖寄乔; 陈达; 林朋; 刘言
Original assignee: Hunan Jingzhou Co ltd
Current assignee: Hunan Jingzhou Co ltd
Priority date: 2023-12-20
Filing date: 2023-12-20
Publication date: 2024-03-26

Abstract

The invention discloses nanoscale graphite emulsion and a preparation method and application thereof. The nano-scale graphite emulsion comprises nano-scale graphite particles, a surfactant, a dispersing agent, a binder, a thickener, an emulsifying agent, a film forming agent, a stabilizing agent, a preservative, a defoaming agent and water, has the characteristics of excellent lubricity, good dispersibility, small sedimentation degree, high stability and the like, is used for drawing metal materials such as fine tungsten and molybdenum wires at high temperature, has excellent coating rate and adhesiveness, has shallow scratches on the surface of drawn metal wires, and greatly improves the quality of the drawn metal wires and the service life of a die.

Description

Nanoscale graphite emulsion and preparation method and application thereof

Technical Field

The invention relates to nanoscale graphite emulsion, a preparation method thereof and application of the nanoscale graphite emulsion in a metal wire drawing process, and belongs to the field of high-temperature-resistant lubricants.

Background

The lubricant is simply a substance interposed between two objects in relative motion, which reduces friction and wear due to contact, and is classified according to physical conditions: gaseous, liquid, semi-solid, solid lubricants. The graphite emulsion is a colloid solution formed by suspending graphite particles in water, belongs to a liquid lubricant, and is widely applied to the drawing process of metal wires, so that the metal wires are prevented from breaking in the high-temperature drawing process.

Chinese patent CN115463986a proposes that the quality of graphite emulsion not only seriously affects the quality of drawn molybdenum wire, but also affects the service life of the die; chinese patent CN110628497a proposes a high temperature resistant lubricant, which can be used at high temperature, has a good lubricating effect, and is not attenuated when used for a long time, so as to effectively protect a lubricating part, but does not disclose specific formulas thereof, such as inorganic separating agents, dispersing agents, etc., and does not define specific use scenes, so that users need to further search, and waste manpower, material resources and financial resources; chinese patent CN103058181a proposes a preparation method of a nano graphene emulsion, which is mainly applied to preparation of composite battery materials, ceramic materials and catalysts, and is not suitable for drawing metal wires; the Chinese patent No. CN104403771A proposes a refractory lubricant for drawing refractory metal and its preparation process, and the particle size of graphite powder is 0.15-1.2 microns, and as known in the industry, the particle size of graphite powder D50 is about 0.932 microns, and the nano level graphite particle is critical to drawing metal filament and is shown in the quality of drawn metal filament: the smaller the particle size of the graphite particles, the shallower the scratches to the wire and the higher the wire quality, but if the particle size of the graphite particles is too small, it is easily oxidized at high temperature to lose the lubrication effect, and the wire may be broken, so that it is important to control the graphite particles in a proper particle size range for the metal drawing process.

Disclosure of Invention

In order to meet the current industrial production needs, the first aim of the invention is to overcome the defects of the prior art, and to provide a nano-scale graphite emulsion which contains nano-scale graphite particles, has the characteristics of excellent lubricity, good dispersibility, small sedimentation degree, high stability and the like, can be used for drawing metal materials such as tungsten filaments, molybdenum filaments and the like at high temperature, and improves the quality of the metal filaments.

The second aim of the invention is to provide a preparation method of nano-scale graphite emulsion, which is simple to operate, low in cost and beneficial to industrial production.

The third purpose of the invention is to provide an application of the nano-scale graphite emulsion, wherein the nano-scale graphite emulsion is used as a high-temperature lubricant to be applied to drawing metal materials such as fine tungsten and molybdenum wires at high temperature, the nano-scale graphite emulsion has excellent coating rate and adhesiveness, scratches on the surface of drawn metal wires are shallower, and the quality of the drawn metal wires and the service life of a die are greatly improved.

In order to achieve the technical purpose, the invention provides nano-scale graphite emulsion which comprises nano-scale graphite particles, a surfactant, a dispersing agent, a binder, a thickening agent, an emulsifying agent, a film forming agent, a stabilizing agent, a preservative, an antifoaming agent and water.

The nano-scale graphite emulsion provided by the invention adopts nano-scale graphite particles, the nano-scale graphite particles are small in particle size and easy to agglomerate, the nano-scale graphite emulsion with good dispersibility, small sedimentation degree and high stability is difficult to form, and the key point of the invention is that a plurality of auxiliary agents such as a surfactant, a dispersing agent, a thickening agent, an emulsifying agent and the like are adopted, and the dispersibility and the stability of the nano-scale graphite particles in water are improved by utilizing the synergistic effect among the auxiliary agents. The surfactant has the function of reducing the surface tension of solid-liquid two phases, and can be modified on the surfaces of the nano graphite particles to improve the surface hydrophilicity of the nano graphite particles; the dispersing agent has the function of reducing clusters among graphite particles and promoting the uniform dispersion of the graphite particles in an aqueous medium; the thickener has the function of reducing the fluidity of the nano-scale graphite emulsion, thereby reducing the sedimentation degree; the emulsifier is used for emulsifying the nano-scale graphite particles into small liquid drops which are uniformly dispersed in the water medium; the stabilizing agent has the functions of improving the chemical stability of the nano-scale graphite emulsion and prolonging the shelf life, and the nano-scale graphite emulsion with good dispersibility, low sedimentation degree and high stability can be formed by compounding the auxiliary agents. In addition, the nano-scale graphite particles have the characteristics of high temperature resistance, friction resistance, good lubricity and the like, but are difficult to uniformly form a film on the surface of a metal wire in the use process, so that the use effect of the nano-scale graphite particles can be influenced. Wherein, the binder has the function of improving the coating rate of the nano-scale graphite emulsion on the metal wire; the film forming agent has the function of forming an interfacial film, which is beneficial to the uniform film forming of nano-scale graphite particles on the surface of the metal wire; the defoamer is used for preventing the nanoscale graphite emulsion from generating bubbles in the use process, so that the coating rate is improved. The auxiliary agents are compounded and used, so that the nano-scale graphite emulsion can be uniformly formed on the surface of the metal wire, the stability of the nano-scale graphite particles is improved, and the lubricating effect of the nano-scale graphite particles is better exerted.

As a preferable scheme, the particle size of the nano-scale graphite particles satisfies D50 less than or equal to 0.5 mu m. Further preferably, the nano-sized graphite particles have a particle diameter satisfying a D50 value of 0.10 to 0.3 μm and a D90 value of 0.90 μm or less. The smaller the particle size of the nano-scale graphite particles, the better the lubrication effect in the drawing process, the shallower the scratches on the metal wire, the higher the quality of the obtained metal wire, but the smaller the particle size of the graphite particles, for example, smaller than 0.1 μm, the graphite particles are easily oxidized at high temperature to lose the lubrication effect, the metal wire is likely to be broken, and the smaller the particle size of the graphite particles is, the easier the agglomeration is, and the stable graphite emulsion is difficult to disperse. The invention controls the graphite particles within the preferable particle size range, not only can obtain stable graphite emulsion, but also is beneficial to improving the metal drawing effect and improving the quality of the metal wire.

As a preferred embodiment, the surfactant is methylene dinaphthyl sulfonate and/or petroleum sulfonate. The preferable surfactant is easy to modify on the surface of nano-scale graphite particles, improves the surface wettability of the nano-scale graphite particles, and improves the dispersibility of the nano-scale graphite particles in an aqueous medium.

As a preferable scheme, the dispersing agent is at least one of sodium carboxymethyl cellulose, sodium dodecyl benzene sulfonate, sodium tripolyphosphate and calcium lignin sulfonate. The preferable dispersing agent is modified on the surface of the nano-scale graphite particles, and clusters among the nano-scale graphite particles are reduced through the actions of static electricity and the like.

As a preferred embodiment, the binder is polyvinyl alcohol and/or polyvinylpyrrolidone. The preferred binder can increase the coating rate of the nano-sized graphite particles on the surface of the wire.

As a preferable scheme, the thickener is at least one of sodium alginate, methylcellulose, hydroxypropyl methylcellulose and polyacrylamide. Preferred thickeners are capable of reducing the fluidity of the nano-scale graphite emulsion, thereby reducing the sedimentation of the nano-scale graphite particles.

As a preferable scheme, the emulsifier is at least one of sodium metasilicate, sodium pyrophosphate and tween 60. Preferred emulsifiers are advantageous for improving the stability of the two-phase system.

As a preferred scheme, the film forming agent is styrene acrylate emulsion and/or epoxy resin. The preferred film former facilitates the formation of an interfacial film and improves the film forming properties of the nano-sized graphite particles on the surface of the wire.

As a preferable scheme, the stabilizer is ammonia water. The preferred stabilizers are advantageous for improving the chemical stability of the nano-scale graphite emulsion. The concentration of ammonia is preferably 25%.

As a preferred embodiment, the preservative is sodium benzoate and/or 5, 5-dimethylhydantoin. Preferred preservatives enhance the shelf life of the product.

As a preferred embodiment, the antifoaming agent is a polysiloxane-based antifoaming agent. The preferred defoamer is advantageous in preventing the nanoscale graphite emulsion from generating bubbles during use, thereby improving the coating rate.

As a preferred scheme, the nano-scale graphite emulsion comprises the following components in percentage by mass: 13% -35% of nano-scale graphite particles; 0.3 to 3 percent of surfactant; 0.1% -3% of dispersing agent; 0.1% -2% of adhesive; 0.2% -5% of thickening agent; 0.1 to 15 percent of emulsifying agent; 0.5 to 10 percent of film forming agent; 2% -5% of stabilizer; 0.1 to 0.5 percent of preservative and 0.1 to 3 percent of defoamer; the balance being water. The surfactant and the dispersing agent with one hydrophilic end and one hydrophobic end in the nano-scale graphite emulsion can promote the affinity of graphite particles and water molecules, the content of the surfactant and the dispersing agent is too low, and the nano-scale graphite particles are easy to agglomerate and are easy to delaminate with water. The content of the binder and the film forming agent is too low, the film forming strength, the wear resistance and the friction force of the nano-scale graphite emulsion are insufficient, and if the content of the binder and the film forming agent is too high, the lubricity of the graphite emulsion is poor. The stabilizer is used for adjusting the pH of the system, and if the pH is too high, the working environment is highly irritant; if the pH is too low, the dispersant and thickener are liable to deteriorate, resulting in coagulation of graphite particles. The film forming agent is used for adjusting the liquid phase density of the system and improving the drying rate of the nano-scale graphite emulsion; the defoamer is used for eliminating bubbles generated by the emulsifier or the adhesive, so that the coating rate of the nano-scale graphite emulsion is improved.

The invention also provides a preparation method of the nanoscale graphite emulsion, which comprises the following steps: 1) Uniformly mixing graphite powder and sodium hydroxide, calcining, and sequentially washing, pickling, washing, drying and crushing a calcined product to obtain graphite particles; 2) Dispersing graphite particles into water under the action of a dispersing agent and a stabilizing agent, adding an emulsifying agent, a binder, a thickening agent, a preservative, a surfactant, a film forming agent and water, and uniformly stirring to form emulsion; 3) Ball milling the emulsion to obtain the nano-scale graphite emulsion.

As a preferable scheme, the mass ratio of the graphite powder to the sodium hydroxide is 1-3:1.

As a preferred embodiment, the conditions for the calcination are: calcining at 500-700 deg.c for 0.5-1.5 hr. The graphite powder and sodium hydroxide are calcined at high temperature, so that metal impurities in the graphite, such as Si, al, fe, ca and Mg, can form silicate and hydroxide, and subsequent washing and removal are facilitated.

As a preferred embodiment, the ball milling conditions are as follows: the rotating speed is 1000-1400 rpm, the ball milling medium is zirconia balls,zirconia beads according to mass ratioThe volume of the zirconia beads accounts for 40-60% of the total volume of the ball milling tank, and the ball milling time is 40-80 h. The ball milling condition is very important for the particle size distribution of the nano-scale graphite particles and the formation of stable emulsion, and under the preferable ball milling condition, the particle size of the obtained nano-scale graphite particles meets the D50 value of 0.10-0.3 mu m and the D90 value of below 0.90 mu m, so that the quality of drawn metal filaments can be ensured. Meanwhile, the ball milling is beneficial to the effect of the auxiliary agent on the nano-scale graphite particles, and the dispersion of the nano-scale graphite particles is promoted to form stable emulsion.

The graphite powder is natural crystalline flake graphite.

The invention also provides application of the nano-scale graphite emulsion, which is used as a high-temperature lubricant to apply a metal wire drawing process.

The invention provides a preparation method of nanoscale graphite emulsion, which comprises the following specific operation processes:

1) Purifying graphite:

high-temperature melting: 100g of graphite powder and 50g of sodium hydroxide are respectively weighed and placed in a crucible, the graphite powder and the sodium hydroxide are uniformly stirred and mixed, and the crucible containing the sample is placed in a muffle furnace at 600 ℃ for calcination for 1 hour, so that metal impurities in the graphite, such as Si, al, fe, ca, mg and the like, form silicate and hydroxide.

Washing: the crucible is cooled to room temperature, the materials are transferred into a polyethylene centrifuge tube, deionized water is added, the suspension is centrifuged in the centrifuge, and then filtered, and filter residues are collected, so that the aim of washing out soluble silicate, hydroxide and most of sodium hydroxide is achieved.

Acid washing: the filter residue after water washing is transferred to a polyethylene centrifuge tube again, and is washed by adding 6% dilute hydrochloric acid for a plurality of times (centrifugation). The pH value of the aqueous phase is tested by using a pH test paper until the solution is acidic, and the washing is stopped, so that the residual sodium hydroxide and insoluble silicate (such as calcium silicate and the like) in the graphite powder are washed off. The sodium hydroxide is melted and then agglomerated, even coated in the graphite inner layer, and cannot be completely removed by water washing.

Washing: and (3) collecting acid-washing filter residues, transferring the materials to a polyethylene centrifuge tube, adding deionized water, centrifuging the suspension in the centrifuge, filtering, testing the pH value of the water phase by using pH test paper, filtering if the water phase is neutral, and collecting the filter residues, otherwise, washing for multiple times. The aim is to remove acid.

And (3) drying: the filter residue was dried for 3 hours at 300℃in a drying oven with the aim of removing water.

Carbon content test: fixed carbon = 1-ash-volatiles. For specific test method, refer to GB/T3518-2008 crystalline flake graphite.

2) Crushed graphite

Wet grinding: taking 100-mesh graphite powder, adding a dispersing agent and water, and putting into a ball mill for ball milling for 60 hours, wherein the ball milling conditions are as follows: the rotation speed is 1200rpm, the ball milling medium is zirconia beads, the mass ratio is 5mm to 1mm to 0.6mm=1 to 3 to 5, and the volume of the zirconia beads is 50% of the volume of the nylon pot.

3) Synthetic graphite emulsion

Preparing milk: placing graphite particles into a nylon tank, adding a dispersing agent, ammonia water, an emulsifying agent, a binding agent, a thickening agent, a preservative, a surfactant, styrene acrylic emulsion, a polysilane defoamer and water, placing the nylon tank filled with the materials into a ball mill for ball milling for 24 hours, and collecting the emulsion.

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

1) The nano-scale graphite emulsion has the characteristics of good dispersibility, low sedimentation degree, high stability and the like, and can be stably stored for a long time.

2) The nano-scale graphite emulsion has the characteristic of excellent lubricity, can be used for drawing metal materials such as fine tungsten and molybdenum wires at high temperature, and improves the quality of the metal wires, wherein the quality is particularly characterized by better wire diameter uniformity, shallower scratch depth and smaller probability of being broken.

3) The preparation method of the nano-scale graphite emulsion is simple to operate, low in cost and capable of meeting the industrial production.

Drawings

FIG. 1 is a scanning electron microscope image of nano graphite particles in nano-scale graphite emulsion; FIG. (a) is the product of example 1; FIGS. (b) - (d) are prior commercial products (TR-26, TR-16 and TR-21); the electron microscope image is obtained by directly drying graphite emulsion at 150 ℃ for 12 hours and testing.

FIG. 2 shows the film formation of the graphite emulsion prepared in comparative example 1 and example 1.

FIG. 3 is a drawing of a wire with application of graphite emulsion; FIGS. (a) and (c) are preparations of example 1; panels (b) and (d) show the prior commercial product preparation (TR-16).

Fig. 4 is a drawing process simple model.

Detailed Description

The following specific examples are intended to illustrate the present invention in further detail, but are not intended to limit the scope of the claims.

The materials referred to in the following specific examples are conventional commercially available materials unless otherwise specified.

Example 1

The nano-scale graphite emulsion for drawing comprises the following main functional components and additives in percentage by mass: 14.3% of graphite particles, 2.2% of sodium carboxymethyl cellulose, 2.1% of ammonia water with the mass fraction of 25%, 2.6% of sodium pyrophosphate, 1.5% of PVP, 1.7% of hydroxypropyl methyl cellulose, 0.2% of 5, 5-dimethyl hydantoin, 2.2% of calcium lignosulfonate, 5.7% of styrene acrylate emulsion (solid content of 45%), 2.19% of polysilane defoamer (medium federal fine chemical Co., ltd.) and the water content of 100%.

1) Purifying graphite:

high-temperature melting: respectively weighing 100g of graphite powder and 50g of sodium hydroxide in a crucible, stirring and mixing the graphite powder and the sodium hydroxide uniformly, and placing the crucible containing the sample in a muffle furnace at 600 ℃ for calcining for 1 hour.

Washing: and cooling the crucible to room temperature, transferring the materials into a polyethylene centrifuge tube, adding deionized water, centrifuging the suspension in a centrifuge, filtering, and collecting filter residues.

Acid washing: the filter residue after water washing is transferred to a polyethylene centrifuge tube again, and is washed by adding 6% dilute hydrochloric acid for a plurality of times (centrifugation). And testing the pH value of the water phase by using pH test paper until the solution is acidic, and stopping washing.

Washing: and (3) collecting acid-washing filter residues, transferring the materials to a polyethylene centrifuge tube, adding deionized water, centrifuging the suspension in the centrifuge, filtering, testing the pH value of the water phase by using pH test paper, filtering if the water phase is neutral, and collecting the filter residues, otherwise, washing for multiple times.

2) Crushed graphite

Wet grinding: taking 30g of graphite powder, adding 3.0g of dispersing agent and 40mL of water, and putting into a ball mill for ball milling for 60 hours, wherein the ball milling conditions are as follows: the rotation speed is 1200rpm, the ball milling medium is zirconia beads, the mass ratio of the zirconia beads is 5mm to 1mm to 0.6mm=1 to 3 to 5, and the filling volume of the zirconia beads is 50% of the volume of the nylon pot.

3) Synthetic graphite emulsion

The graphite emulsion (taking 30g of graphite powder as a reference) is prepared according to the raw material ratio: placing graphite particles into a nylon tank, adding sodium carboxymethyl cellulose, ammonia water, sodium pyrophosphate, PVP, hydroxypropyl methylcellulose, 5-dimethyl hydantoin, calcium lignosulfonate, styrene acrylate emulsion, polysilane defoamer and water, placing the nylon tank filled with the materials into a ball mill, ball milling for 24 hours, and collecting the emulsion.

Example 2

The nano-scale graphite emulsion for drawing comprises the following main functional components and additives in percentage by mass: 21.4% of graphite particles, 2.2% of sodium carboxymethyl cellulose, 2.1% of ammonia water with the mass fraction of 25%, 3.7% of sodium pyrophosphate, 0.7% of PVP, 0.24% of hydroxypropyl methyl cellulose, 0.25% of 5, 5-dimethyl hydantoin, 2.2% of calcium lignosulfonate, 6.7% of styrene acrylate emulsion (solid content of 45%), 2.19% of polysilane defoamer (medium federal fine chemical Co., ltd.) and the water content of 100%.

1) The method of purifying graphite and pulverizing graphite is the same as in example 1, and will not be described again.

2) Synthetic graphite emulsion

Example 3

The nano-scale graphite emulsion for drawing comprises the following main functional components and additives in percentage by mass: 21.4% of graphite particles, 2.7% of sodium dodecyl benzene sulfonate, 3.0% of ammonia water with the mass fraction of 25%, 5.7% of sodium metasilicate, 0.5% of polyvinyl alcohol, 0.24% of sodium alginate, 0.3% of sodium benzoate, 2.7% of calcium lignin sulfonate, 6.7% of styrene acrylate emulsion (solid content of 45%), 2.19% of polysilane defoamer (medium federal fine chemical Co., ltd.) and the water content of the polysilane defoamer to be 100%.

2) Synthetic graphite emulsion

The graphite emulsion (taking 30g of graphite powder as a reference) is prepared according to the raw material ratio: putting graphite particles into a nylon pot, adding sodium dodecyl benzene sulfonate, ammonia water, sodium metasilicate, polyvinyl alcohol, sodium alginate, sodium benzoate, calcium lignin sulfonate, styrene acrylate emulsion, polysilane defoamer and water, putting the nylon pot with the materials into a ball mill for ball milling for 24 hours, and collecting emulsion.

The results of the nano-scale graphite emulsion physical and chemical item test for drawing described in the above examples 1 to 3 are shown in Table 1.

TABLE 1

The physicochemical results of examples 1 to 3 were obtained by testing according to GB/T15064-2008 and GB/T15064.4-1994.

Comparative example 1

In contrast to example 1, no styrene acrylate emulsion was added. As shown in fig. 2, it can be seen that the film formed was not uniform and had a large number of cracks without using the styrene acrylate emulsion.

Application examples

To draw and drawThe wire-cutting tungsten filament with the specification is taken as an example, and the wire drawing structure is shown in figure 3.

1. The nano-scale graphite emulsion of the example 1 and pure water are mixed according to the weight ratio of 1:4, and are stirred for 6-7 hours by a mechanical stirrer at the rotation speed of 1200rpm for later use.

2. A 59.00mg/200mm tungsten wire is fixed on paying-off equipment, a heating die is started, the temperature is set to be 750-850 ℃, and the compression ratio is 20%.

3. And filling the graphite emulsion into a groove at the front end of the heating and drying zone so as to dry in the heating zone.

4. Passing tungsten wire to be drawn throughAnd the hard alloy die with the aperture is connected to the wire connecting equipment.

5. Starting a wire drawing machine, enabling a tungsten wire to be drawn to pass through a 650cm heating and drying area at a constant speed of 10m/min, passing through a hard alloy die, and finally collecting on a wire collecting device to obtainTungsten wire of a specification.

With the existing commercial graphite emulsion product (TR-16) as a control.

The drawing effect is shown in fig. 2, and it can be seen from fig. 2 that the graphite emulsion of example 1 was used in the drawing process, and the scratch depth on the surface of the wire was shallower.

Claims

1. A nanoscale graphite emulsion, which is characterized in that: comprises nano-scale graphite particles, a surfactant, a dispersing agent, a binder, a thickening agent, an emulsifying agent, a film forming agent, a stabilizing agent, a preservative, a defoaming agent and water.

2. The nanoscale graphite emulsion of claim 1, wherein: the particle size of the nano-scale graphite particles meets the requirement that D50 is less than or equal to 0.5 mu m.

3. The nanoscale graphite emulsion of claim 1, wherein:

the surfactant is at least one of methylene dinaphthyl sulfonate, calcium lignosulfonate, petroleum sulfonate and sodium dodecyl sulfate;

the dispersing agent is at least one of sodium carboxymethyl cellulose and/or sodium dodecyl benzene sulfonate;

the binder is polyvinyl alcohol and/or polyvinylpyrrolidone;

the thickener is at least one of sodium alginate, methyl cellulose, hydroxypropyl methyl cellulose and polyacrylamide;

the emulsifier is at least one of sodium metasilicate, sodium pyrophosphate and tween 60;

the film forming agent is styrene acrylic ester emulsion and/or epoxy resin;

the stabilizer is ammonia water;

the preservative is sodium benzoate and/or 5, 5-dimethyl hydantoin;

the defoaming agent is polysiloxane defoaming agent.

4. A nanoscale graphite emulsion according to any one of claims 1 to 3, wherein: comprises the following components in percentage by mass:

13% -35% of nano-scale graphite particles;

0.3 to 3 percent of surfactant;

0.1% -3% of dispersing agent;

0.1% -2% of adhesive;

0.2% -5% of thickening agent;

0.1 to 15 percent of emulsifying agent;

0.5 to 10 percent of film forming agent;

2% -5% of stabilizer;

0.1 to 0.5 percent of preservative;

0.1% -3% of defoaming agent;

the balance being water.

5. The method for preparing nano-scale graphite emulsion according to any one of claims 1 to 4, wherein: the method comprises the following steps:

1) Uniformly mixing graphite powder and sodium hydroxide, calcining, and sequentially washing, pickling, washing, drying and crushing a calcined product to obtain graphite particles;

2) Dispersing graphite particles into water under the action of a dispersing agent and a stabilizing agent, adding an emulsifying agent, a binder, a thickening agent, a preservative, a surfactant, a film forming agent, a defoaming agent and water, and uniformly stirring to form turbid liquid;

3) Ball milling the turbid liquid to obtain the nano-scale graphite emulsion.

6. The method for preparing nano-scale graphite emulsion according to claim 5, wherein: the mass ratio of the graphite powder to the sodium hydroxide is 1-3:1.

7. The method for preparing nano-scale graphite emulsion according to claim 5, wherein: the conditions of the calcination are as follows: calcining at 500-700 deg.c for 0.5-1.5 hr.

8. The method for preparing nano-scale graphite emulsion according to claim 5, wherein: the ball milling conditions are as follows: the rotating speed is 1000-1400 rpm, the ball milling medium is zirconia beads, the zirconia beads are formed by the mass ratio phi 5mm, phi 1mm, phi 0.6 mm=1:2-4:4-6, the volume of the zirconia beads accounts for 40-60% of the total volume of the ball milling tank, and the ball milling time is 40-80 h.

9. Use of a nano-scale graphite emulsion as claimed in any one of claims 1 to 4, characterized in that: the wire drawing process is applied as a high temperature lubricant.