阅读说明：本技术 一种石墨烯负载球状金属的制备方法 (Preparation method of graphene loaded spherical metal ) 是由 戴乐阳 廖海峰 于 2019-09-30 设计创作，主要内容包括：本发明涉及石墨烯复合材料技术领域,特别涉及一种石墨烯负载球状金属的制备方法,包括：制备膨胀石墨；利用等离子体辅助高能球磨装置,以油酸作为湿磨介质和表面修饰剂,将铜和锡的混合金属粉末进行球磨,并进行高压放电处理,以Ar气作为放电气体；在离子体辅助高能球磨装中,加入膨胀石墨,进行球磨处理和高压放电处理,以Ar气作为放电气体；将冷却后得到的球磨混合物与石油醚混合后,进行相应处理,即获得石墨烯负载球状金属。本发明所制备的石墨烯负载球状金属,能够作为润滑油的添加剂使用,提高润滑油的减摩抗磨性能,减少机械零件的磨损,不仅能够修复基材表面的受损面,还能够对基材表面形成良好的薄膜保护,具有重要的实际应用价值。(The invention relates to the technical field of graphene composite materials, in particular to a preparation method of graphene loaded spherical metal, which comprises the following steps: preparing expanded graphite; performing ball milling on mixed metal powder of copper and tin by using a plasma-assisted high-energy ball milling device and oleic acid as a wet milling medium and a surface modifier, and performing high-pressure discharge treatment, wherein Ar gas is used as discharge gas; adding expanded graphite into the plasma-assisted high-energy ball milling device, and performing ball milling treatment and high-voltage discharge treatment by using Ar gas as discharge gas; and mixing the ball-milled mixture obtained after cooling with petroleum ether, and performing corresponding treatment to obtain the graphene loaded spherical metal. The graphene loaded spherical metal prepared by the invention can be used as an additive of lubricating oil, the antifriction and antiwear performance of the lubricating oil is improved, the abrasion of mechanical parts is reduced, the damaged surface of the surface of a base material can be repaired, good film protection can be formed on the surface of the base material, and the graphene loaded spherical metal has important practical application value.)

1. A preparation method of graphene loaded spherical metal is characterized by comprising the following preparation steps:

step a, preparing expanded graphite;

b, ball milling mixed metal powder of copper and tin by using a plasma auxiliary high-energy ball milling device and oleic acid as a wet milling medium and a surface modifier, wherein high-voltage discharge treatment is carried out in the ball milling process, and the discharge voltage is 25 KV-28 KV; ar gas is filled in the ball milling tank to be used as discharge gas, and the pressure in the ball milling tank is controlled to be 0.01-0.03 MPa;

c, adding expanded graphite into the plasma-assisted high-energy ball milling device, performing ball milling treatment, and performing high-pressure discharge treatment, wherein the discharge voltage is 18 KV-20 KV, Ar gas is filled in the ball milling tank as discharge gas, and the pressure in the ball milling tank is controlled to be 0.10-0.50 Mpa;

and d, mixing the ball-milled mixture obtained after cooling with petroleum ether, performing ultrasonic oscillation, then performing precipitation, collecting supernatant liquid, performing centrifugal treatment, and drying a centrifugal product to obtain powder, namely the graphene loaded spherical metal.

2. The method for producing a graphene-supported spherical metal according to claim 1, characterized in that: the mass ratio of copper to tin is 1.0-1.5: 1.

3. the method for producing a graphene-supported spherical metal according to claim 1, characterized in that:

in the step a, the preparation method of the expanded graphite comprises the following steps: heating the box-type resistance furnace to 1000-1200 ℃, adding expandable graphite into the furnace, and expanding at high temperature to obtain the expanded graphite.

4. The method for producing a graphene-supported spherical metal according to claim 1, characterized in that: in the step b, the ball milling time is 5-10 h; in the step c, the ball milling time is 5-10 h.

5. The method for producing a graphene-supported spherical metal according to claim 1, characterized in that:

in the step b and the step c, the vertical vibration frequency of the ball mill is 20-25 Hz, and the amplitude is 10-13 mm.

6. The method for producing a graphene-supported spherical metal according to claim 1, characterized in that: in the step c, the mass ratio of the mixed metal powder to the expanded graphite is 1: 5 to 10.

7. The method for producing a graphene-supported spherical metal according to claim 1, characterized in that: in the step c, before adding the expanded graphene, adding fatty acid polyglycol ester into a plasma-assisted high-energy ball milling device, wherein the mass ratio of the metal powder to the fatty acid polyglycol ester is 1: 1 to 1.5.

8. The method for producing a graphene-supported spherical metal according to claim 1, characterized in that:

in the step d, the drying temperature is 100-120 ℃ when the drying treatment is carried out.

9. The method for producing a graphene-supported spherical metal according to claim 1, characterized in that:

in the step e, the mixing ratio of the ball-milling mixture to the petroleum ether is 1: 1.

Technical Field

The invention relates to the technical field of graphene composite materials, in particular to a preparation method of graphene loaded spherical metal.

Background

The piston ring-cylinder sleeve is one of the main moving pairs of the marine diesel engine, and the lubrication of the piston ring-cylinder sleeve directly influences the fuel economy, the durability and even the service life of the whole marine diesel engine. If the piston ring-cylinder sleeve is not properly lubricated, not only can the fuel consumption be increased, but also the components can be excessively worn, so that the clearance between the piston and the cylinder sleeve is too large, and even a serious accident such as cylinder pulling can occur, and the dynamic property of the diesel engine is lost.

In order to control the emission of the marine diesel engine, the IMO requires that the marine diesel engine uses low-sulfur fuel oil, but the marine diesel engine uses the low-sulfur fuel oil to cause abnormal wear of key parts such as a piston ring, a cylinder sleeve and the like to become very prominent, because the low-base-number lubricating oil matched with the low-sulfur fuel oil has relatively poor detergency and thermal stability, the pollution of a piston ring groove, the adhesion of a piston ring and a paint film on the inner wall of the cylinder sleeve are easily caused; secondly, the high content of aluminum/silicon particles in the low-sulfur fuel oil enters the combustion chamber to increase abrasive wear of the cylinder sleeve, and in severe cases, cylinder pulling and even cylinder biting are induced. It follows that the use of low sulphur fuels causes severe wear of the cylinder liners of diesel engines, increases the difficulty and intensity of the management of the turbines and may cause sudden stops in SECA areas or in severe sea conditions, seriously jeopardizing the safety of the ship.

The current nano lubricating oil additive mainly comprises metal, oxide, sulfide, graphene and the like. Wherein, the nano metal as the lubricant additive has obvious abrasion resistance and repair function on the abrasion surface of the steel substrate. However, most metal particles are hydrophilic on their surface, are difficult to disperse in lubricating oils, and are prone to agglomeration and precipitation, thereby affecting the quality of the lubricating oils.

The existing lubricant additive exists in the form of irregular particles, and the nano metal can not only repair the surface of a worn rigid base material but also cannot form a long-term protection effect on a steel base material.

Disclosure of Invention

In order to solve the problems mentioned in the background art, the invention provides a preparation method of graphene loaded spherical metal, which comprises the following preparation steps:

step a, preparing expanded graphite;

b, ball milling mixed metal powder of copper and tin by using a plasma auxiliary high-energy ball milling device and oleic acid as a wet milling medium and a surface modifier, wherein high-voltage discharge treatment is carried out in the ball milling process, and the discharge voltage is 25 KV-28 KV; ar gas is filled in the ball milling tank to be used as discharge gas, and the pressure in the ball milling tank is controlled to be 0.01-0.03 MPa;

c, adding expanded graphite into the plasma-assisted high-energy ball milling device, performing ball milling treatment, and performing high-pressure discharge treatment, wherein the discharge voltage is 18 KV-20 KV, Ar gas is filled in the ball milling tank as discharge gas, and the pressure in the ball milling tank is controlled to be 0.10-0.50 Mpa;

and d, mixing the ball-milled mixture obtained after cooling with petroleum ether, performing ultrasonic oscillation, then performing precipitation, collecting supernatant liquid, performing centrifugal treatment, and drying a centrifugal product to obtain powder, namely the graphene loaded spherical metal.

On the basis of the scheme, the mass ratio of copper to tin is 1.0-1.5: 1.

on the basis of the scheme, in the step a, the preparation method of the expanded graphite comprises the following steps: heating the box-type resistance furnace to 1000-1200 ℃, adding expandable graphite into the furnace, and expanding at high temperature to obtain the expanded graphite.

On the basis of the scheme, further, in the step b, the ball milling time is 5-10 h; in the step c, the ball milling time is 5-10 h.

On the basis of the scheme, in the step b and the step c, the vertical vibration frequency of the ball mill is 20-25 Hz, and the amplitude is 10-13 mm.

On the basis of the scheme, in the step c, the mass ratio of the mixed metal powder to the expanded graphite is 1: 5 to 10.

On the basis of the scheme, further, in the step c, before adding the expanded graphene, adding fatty acid polyglycol ester into a plasma-assisted high-energy ball milling device, wherein the mass ratio of the metal powder to the fatty acid polyglycol ester is 1: 1 to 1.5.

On the basis of the above scheme, further, in the step d, when the drying treatment is performed, the drying temperature is 100 ℃ to 120 ℃.

On the basis of the scheme, in the step e, the mixing ratio of the ball-milling mixture to the petroleum ether is 1: 1.

the graphene loaded spherical metal prepared by the preparation method provided by the invention can be used as an additive of lubricating oil, so that the lubricating and antifriction wear-resisting properties of the lubricating oil can be greatly improved, the wear of mechanical parts is reduced, the damaged surface of the base material can be repaired, a good film protection is formed on the surface of the base material, a long-term protection effect is achieved, and the preparation method has an important practical application value.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description will be given below to the drawings required for the description of the embodiments or the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is an SEM image of expandable graphite and expanded graphite;

fig. 2 is TEM images before and after modification of graphene oxide with oleic acid;

fig. 3 is a SEM image of a product prepared by the preparation method provided by the present invention, which is a graphene-loaded spherical metal;

fig. 4 is a TEM image of a product prepared by the preparation method provided in example 1, the product being a graphene-supported spherical metal;

fig. 5 is a TEM image of a product prepared by the preparation method provided in example 2, the product being a graphene-supported spherical metal;

FIG. 6 is a graph showing a precipitation dispersion experiment performed on samples prepared in comparative example 1, example 1 and example 2;

FIG. 7 is a comparative plot of scrub radius tests conducted on base lubricant R3209 and a compounded oil of example 1 sample added in an amount of 0.05 wt.%, example 2 sample and comparative example 1 sample added in an amount of 0.05 wt.% in base lubricant R3209;

FIG. 8 is a graph showing the friction coefficient test conducted on base lubricant R3209, and the compounded oil of the sample of example 1 added in an amount of 0.05 wt%, the sample of example 2, and the sample of comparative example 1 added in an amount of 0.05 wt% in base lubricant R3209.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The present invention provides the following examples:

example 1

Step a, preparing expanded graphite:

heating a box type resistance furnace to 1000 ℃, adding 20g of expandable graphite into the furnace, and expanding at high temperature for 80s to obtain expanded graphite;

b, mixing 1.5g of copper and 1.5g of tin metal powder by using a plasma-assisted high-energy ball milling device and using 500ml of oleic acid as a wet milling medium and a surface modifier, and then carrying out ball milling in the plasma-assisted high-energy ball milling device, wherein high-pressure discharge treatment is carried out in the ball milling process, and the discharge voltage is 25 KV; ar gas is filled in the ball milling tank as discharge gas, and the pressure in the ball milling tank is controlled to be 0.03 MPa;

the vertical vibration frequency of the ball mill is 22Hz, the amplitude is 10mm, and the ball milling time is 10 h;

c, adding 15g of expanded graphite into the plasma-assisted high-energy ball milling device, performing ball milling treatment, performing high-pressure discharge treatment, wherein the discharge voltage is 20KV, Ar gas is filled in the ball milling tank as discharge gas, and the pressure in the ball milling tank is controlled to be 0.20 Mpa; the vertical vibration frequency of the ball mill is 22Hz, the amplitude is 10mm, and the ball milling time is 6 h;

and d, mixing the ball-milled mixture obtained after cooling with petroleum ether 1: 1, mixing, carrying out ultrasonic oscillation for 2 hours, placing into a centrifuge tube, standing for 1.5 hours to allow the mixture to naturally settle, removing the sediments with larger particles at the lower layer, carrying out centrifugal treatment on the upper layer solution at a centrifugal rate of 9500r/m for 30min by using a Hunan instrument H1850 desktop high-speed centrifuge, and drying the centrifugal product at 110 ℃ to obtain powder, namely the graphene-loaded spherical metal.

Example 2

Step a, preparing expanded graphite:

heating a box type resistance furnace to 1000 ℃, adding 20g of expandable graphite into the furnace, and expanding at high temperature for 80s to obtain expanded graphite;

b, mixing 1.0g of copper and 1.5g of tin metal powder by using a plasma-assisted high-energy ball milling device and using 500ml of oleic acid as a wet milling medium and a surface modifier, and then carrying out ball milling in the plasma-assisted high-energy ball milling device, wherein high-pressure discharge treatment is carried out in the ball milling process, and the discharge voltage is 25 KV; ar gas is filled in the ball milling tank as discharge gas, and the pressure in the ball milling tank is controlled to be 0.01 Mpa;

the vertical vibration frequency of the ball mill is 22Hz, the amplitude is 10mm, and the ball milling time is 10 h;

step c, weighing 15g of fatty acid polyglycol ester, adding the weighed fatty acid polyglycol ester into a plasma-assisted high-energy ball milling device, adding 15g of expanded graphite, carrying out ball milling treatment, and carrying out high-pressure discharge treatment, wherein the discharge voltage is 20KV, Ar gas is filled in a ball milling tank as discharge gas, and the pressure in the ball milling tank is controlled to be 0.30 Mpa; the vertical vibration frequency of the ball mill is 22Hz, the amplitude is 10mm, and the ball milling time is 6 h;

and d, mixing the ball-milled mixture obtained after cooling with petroleum ether 1: 1, mixing, carrying out ultrasonic oscillation for 2 hours, placing into a centrifuge tube, standing for 1.5 hours to allow the mixture to naturally settle, removing the sediments with larger particles at the lower layer, carrying out centrifugal treatment on the upper layer solution at a centrifugal rate of 9500r/m for 30min by using a Hunan instrument H1850 desktop high-speed centrifuge, and drying the centrifugal product at 115 ℃ to obtain powder, namely the graphene-loaded spherical metal.

Comparative example 1

Step a, preparing expanded graphite:

heating a box type resistance furnace to 1000 ℃, adding 15g of expandable graphite into the furnace, and expanding at high temperature for 80s to obtain expanded graphite;

b, using a plasma-assisted high-energy ball milling device, using 500ml of oleic acid as a wet milling medium and a surface modifier, and using 1.5g of copper and 1.5g of tin metal powder which are mixed and 5g of expanded graphite as raw materials to perform ball milling to obtain a ball milling mixture;

ar gas is filled in the ball milling tank as protective gas, the pressure in the ball milling tank is controlled to be 0.1Mpa, the vertical vibration frequency of the ball mill is 16Hz, the amplitude is 10mm, and the ball milling time is 10 h;

step c, cooling after the ball milling is finished;

and d, mixing the ball-milled mixture obtained after cooling with petroleum ether 1: 1, mixing, performing ultrasonic oscillation for 2 hours, placing into a centrifuge tube, standing for 1 hour to allow the centrifuge tube to naturally settle, removing sediments with larger particles at the lower layer, centrifuging the upper layer solution for 30min at a centrifuging speed of 9500r/m by using a Hunan instrument H1850 desktop high-speed centrifuge, and drying the centrifuged product at 153 ℃ to obtain powder, namely the graphene-loaded spherical metal.

In the preparation method provided by the invention, expandable graphite is added into a box-type resistance furnace after the furnace is heated to 1000-1200 ℃, and the expandable graphite is obtained after high-temperature expansion. Specifically, as shown in FIG. 1, FIG. 1(a) shows expandable graphite, and FIG. 1(b) shows the prepared expandable graphite; the expandable graphite is in a planar flake structure, the lamellar structure is compact, the thickness of the lamellar is in a micron level, and the particle size is about 300 mu m. After high-temperature treatment, the surface appearance of the expanded graphite is loose honeycomb, the thickness of a lamella is still in a micron level, and the particle size is crushed to about 10 mu m. This is because the structural layers of the expandable graphite are connected by weak van der waals force, and a large amount of carbon dioxide and sulfur dioxide gas is generated during high-temperature treatment, so that the expandable graphite is expanded and broken in a direction perpendicular to the carbon-based surface to form the expanded graphite. The expanded graphite subjected to expansion treatment has the advantages that the structural layer spacing is increased, the particle size is greatly reduced, and the graphene can be more favorably peeled.

According to the preparation method, oleic acid is used as a wet grinding medium and a surface modifier, expanded graphite and mixed metal powder are treated by a ball milling process, wherein the expanded graphite can be scraped and embedded by the metal powder, and then the stripping of graphene is effectively promoted by utilizing a thermal explosion effect, so that the metal powder can be loaded on the surface of the graphene.

Fig. 2 is SEM expanded graphite images of ball milling for 5h (a) and ball milling for 10h (b), and it can be seen from fig. 2 that the expanded graphite with micron size is refined to nanometer size, and after 5h of plasma-assisted ball milling, the graphite layer structure is largely stripped, and the edge part is stripped to form a thin yarn-like graphene structure; with the increase of the ball milling time to 10h, the corrugation and undulation of the graphene are more obvious and are semitransparent, which means that the number of graphite layers is continuously reduced and thinned, and it can be seen that with the increase of the plasma-assisted ball milling time, the positive stress and the shearing force generated by the impact between the stainless steel grinding balls enable the graphene sheet layers to be gradually stripped from the expanded graphite, and the heat effect of the plasma and the micro-area thermal explosion effect help to overcome the weak bonding force between the graphite sheet layers, so that the distance between the expanded graphite sheet layers is further expanded, and the expansion stripping of the graphite is promoted.

In the ball milling process, oleic acid is used as a graphite medium and a surface modifier, the ball milling is assisted by 10 hours of plasma, and under the synergistic action of the impact of grinding balls and the pulse and bombardment of the plasma on molecular bonds of the oleic acid, the oleic acid is gasified and cracked to obtain a large amount of-CH-containing substances₂Long alkanes, -these-CH₂The functional groups are grafted to the surface of the (oxidized) graphene, modifying the sample to a non-polar structure, which in turn makes it oleophilic and hydrophobic.

In the scheme of the invention, mixed metal powder of copper and tin is adopted for ball milling, wherein the melting point of tin is 231 ℃, and the Mohs hardness is 1.5; the melting point of copper is 1083 ℃, the Mohs hardness is 3, and the high-pressure discharge thermal explosion treatment is carried out in the ball milling process by utilizing the difference between the melting point and the hardness of the two metals, so that the copper is used as an inner core, and the tin metal is attached to the surface of the copper; the ductility of tin is excellent, can form preliminary restoration to impaired steel surface, and copper metal powder can guarantee the rolling friction on steel surface under certain frictional pressure as the kernel, guarantees the lubricity, and after pressure reaches certain intensity, the copper powder that the mohs hardness is 3 can prevent that steel surface form from causing the granule to rub, and the ductility of copper also can form secondary restoration to impaired steel surface simultaneously.

According to the technical scheme provided by the invention, mixed metal is subjected to high-pressure discharge ball milling, then expanded graphite is added for high-pressure discharge ball milling, the discharge parameters and the pressure in a ball milling tank are controlled, and simultaneously, the expanded graphene is directly subjected to ball milling and scraping to prepare graphene, so that the prepared product is in the form of graphene-loaded spherical metal, specifically shown in figure 3, namely spherical metal particles are loaded on the surface of the graphene with a certain surface, wherein figure 4 is a sample prepared in example 1; the lubricant additive prepared from the product in the form can improve the lubricity by utilizing spherical metal particles, and relatively expanded graphene can better form a coating on the surface of a steel material, so that the surface of the steel material is protected. The lubricating property of graphene can also be improved, and meanwhile, metal particles attached to the surface of graphene and in contact with the surface of steel can also repair the damaged surface of steel.

Preferably, as shown in example 2, before the expanded graphene is added, the fatty acid polyglycol ester is added into the plasma-assisted high-energy ball milling device, and compared with the sample prepared in example 1, the fatty acid polyglycol ester has a dispersion property that the mixed metal powder can be more uniformly dispersed on the surface of the graphene (as shown in fig. 5).

The samples prepared in example 1, example 2 and comparative example 1 are added to lubricating oil of base oil R3209 in an amount of 0.05 wt% and mixed uniformly, and then the mixture is left to stand for one week, and the test observation result is shown in FIG. 6, wherein FIG. 6 is a precipitation dispersion experimental diagram, and the samples in the diagram are sequentially as follows from left to right: comparative example 1, example 2; as can be seen from fig. 6, the high-pressure discharge ball milling method provided by the present invention can better improve the dispersibility and stability of the sample, while as shown in the embodiment of example 2, the stability and dispersibility of the sample are better improved after the fatty acid polyglycol ester is added.

A base lubricating oil R3209 and a composite oil which is added with 0.05 wt% of the sample of the embodiment 1, the sample of the embodiment 2 and the sample of the comparative example 1 are added into the base lubricating oil R3209, a vertical universal friction wear testing machine (MM-W1A) is utilized, a four-ball friction experiment is carried out under the working conditions that the test load is 300N and the rotating speed is 500R/min, and the grinding spot experiment of steel balls is carried out, the grinding spot radius is tested, as shown in figure 7, compared with the base oil and the comparative example, the additive provided by the invention can obviously reduce the grinding spot radius and better improve the lubricating property.

The CFT-1 material surface property comprehensive tester is used for testing the friction coefficients of the base oil R3209 and the compound oil of the sample of example 1, the sample of example 2 and the sample of comparative example 1 in an amount of 0.05 wt% added into the base lubricating oil R3209 respectively, and the test result is shown in figure 8.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.