阅读说明：本技术 一种石墨烯/金属氧化物纳米复合润滑材料制备方法 (Preparation method of graphene/metal oxide nano composite lubricating material ) 是由 赵军 黄轶遥 李英儒 刘益江 高彤 李庆展 李双喜 于 2019-11-02 设计创作，主要内容包括：本发明提供了制备一种低缺陷二维石墨烯/金属氧化物纳米复合润滑材料的方法,该方法包括：(1)对石墨进行高度氧化处理,得到充分氧化石墨；(2)对所述氧化石墨与可溶性金属盐球磨混合,使得氧化石墨充分剥离成氧化石墨烯,同时将金属离子充分附着在氧化石墨烯表面和层间；(3)对所述溶液进行水解和定向聚合处理,将氧化石墨烯上附着的金属离子转化为纳米氢氧化物；(4)对所述反应后的黑色浆状物进行加热和除杂处理,得到低缺陷二维石墨烯/金属氧化物纳米复合润滑材料。通过该方法能够快速有效的制备性能优异的低缺陷石墨烯/金属氧化物纳米复合润滑材料,步骤简单、操作方便,绿色环保,可批量生产且经济性好。(The invention provides a method for preparing a low-defect two-dimensional graphene/metal oxide nano composite lubricating material, which comprises the following steps: (1) carrying out high-degree oxidation treatment on graphite to obtain sufficient graphite oxide; (2) ball-milling and mixing the graphite oxide and soluble metal salt to fully strip the graphite oxide into graphene oxide, and simultaneously fully attaching metal ions to the surface and the layers of the graphene oxide; (3) carrying out hydrolysis and directional polymerization treatment on the solution, and converting metal ions attached to the graphene oxide into nano hydroxide; (4) and heating and impurity removal treatment are carried out on the reacted black slurry to obtain the low-defect two-dimensional graphene/metal oxide nano composite lubricating material. The method can be used for quickly and effectively preparing the low-defect graphene/metal oxide nano composite lubricating material with excellent performance, has simple steps, is convenient to operate, is green and environment-friendly, can be used for batch production, and is good in economical efficiency.)

1. A preparation method of a low-defect two-dimensional graphene/metal oxide nano composite lubricating material is characterized by comprising the following steps:

(1) carrying out high-degree oxidation treatment on graphite to obtain sufficient graphite oxide;

(2) performing ball milling mixing reaction on the graphite oxide and soluble metal salt to obtain graphene oxide with metal ions fully attached to the surface and the layers;

(3) fully hydrolyzing and directionally polymerizing the reacted solution to convert metal ions attached to the graphene into nano hydroxide;

(4) heating the reacted black slurry to uniformly load nano metal oxide on the surface and between layers of the graphene;

(5) and performing ball milling and crushing treatment on the graphene/metal oxide nano composite lubricating material to obtain the low-defect two-dimensional graphene/metal oxide nano composite lubricating material.

2. The method of claim 1, wherein step (1) further comprises:

(1-1) mixing a mixture of sulfuric acid and potassium permanganate with graphite at 0-5 ℃, and carrying out an oxidation reaction on the obtained mixture at 40-60 ℃ for 2-10 hours;

(1-2) mixing the reaction product obtained in the step (1-1) with deionized water, and preserving heat for 0.5-5 hours at the temperature of 60-80 ℃;

and (1-3) mixing the reaction product obtained in the step (1-2) with hydrogen peroxide to obtain the graphite oxide.

3. The method according to claim 2, wherein in the step (1-1), the mass ratio of the sulfuric acid to the potassium permanganate is 2-6: 1, the mass ratio of the mixture of sulfuric acid and potassium permanganate to the graphite is 50-100: 1.

4. the method according to claim 2, wherein in the step (1-2), the mass ratio of the deionized water to the graphite is 200-1000: 1.

5. the method of claim 2, wherein step (1) further comprises:

(1-4) washing and drying the graphite oxide.

6. The method of claim 1, wherein step (2) further comprises:

(2-1) after filtration, the mixture was filtered by a filtration method using 1: and (5) washing 1000-5000 ml of HCl solution of 10 to remove residual manganese ions to obtain a golden yellow filter cake.

And (2-2) re-dispersing the golden yellow filter cake into 500-5000 ml of deionized water, uniformly stirring, and slowly adding soluble metal salt to form a mixture. The mass ratio of the filter cake to the metal salt is 1: 1-50, the metal salt can be CuCl2, CuSO4, FeCl3 and the like.

And (2-3) fully stirring and mixing the mixture in a high-energy ball mill to obtain fully stripped graphene oxide, and fully attaching metal ions to the surface and the layers of the graphene oxide. The mixing speed is 300-1000 rpm, and the mixing time is 4-40 hours.

7. The method of claim 1, wherein step (3) is specifically operative to:

and slowly adding a strong base solution, controlling the final pH to be 8-14, converting the dispersion liquid into a black suspension, and standing the dispersion liquid for 2-20 hours.

8. The method of claim 1, wherein step (4) is specifically operative to:

the black suspension was heated to boiling until the suspension completely evaporated to a black solid.

9. The method of claim 1, wherein step (5) is specifically operative to:

washing and filtering the black slurry, drying the filtered black slurry in an oven at 80 ℃, and then performing ball milling and sieving treatment.

10. A low-defect two-dimensional graphene/metal oxide nanocomposite lubricant material, characterized by being prepared by the method of any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of nano materials, in particular to a preparation method of a low-defect two-dimensional graphene/metal oxide nano composite lubricating material. .

Background

Graphene is a two-dimensional crystal formed by close packing of carbon atoms, the carbon atoms in the graphene are arranged in a manner of sp2 hybrid orbital bonding, and the graphene has the following characteristics: the carbon atom has 4 valence electrons, wherein 3 electrons generate sp2 bonds, i.e., each carbon atom contributes an unbound electron located on the pz orbital, the pz orbitals of neighboring atoms form pi bonds in a direction perpendicular to the plane, and the newly formed pi bonds are in a half-filled state. The coordination number of carbon atoms in graphene is 3, and the bond length between every two adjacent carbon atoms is 1.42 × 10^-10Rice, the included angle between the keys is 120 degrees. The delta bonds are bonded to other carbon atoms in a hexagonal honeycomb layered structure, and the pz orbitals of the perpendicular layer planes for each carbon atom can form large pi bonds (similar to benzene rings) throughout the multi-atoms of the entire layer. Graphene is one of the materials with the highest known strength, has good toughness and can be bent, the theoretical Young modulus is 1.0TPa, and the inherent tensile strength is 130 GPa. The carrier mobility of graphene at room temperature is about 15000cm²V.s, up to 250000cm under certain specific conditions, e.g. low temperature²V.s. Unlike many materials, the electron mobility of graphene is less affected by temperature changes, and the electron mobility of single-layer graphene is kept at 15000cm at any temperature between 50 and 500K²And (V.s) is about good in conductivity. Meanwhile, the graphene has good heat conduction performance, the heat conductivity coefficient of pure defect-free single-layer graphene reaches 5300W/mK, and the graphene is a carbon material with the highest heat conductivity coefficient at present and is higher than that of a single-wall carbon nanotube (3500W/mK) and a multi-wall carbon nanotube (3000W/mK). The graphene has very good optical performance and can be used for a wide range of wavelengthsIn the range, the systemic yield is about 2.3%, and it appears almost transparent. In the range of several layers of graphene, the absorption increases by about 2.3% for each additional layer in thickness. Due to the excellent characteristics, the graphene has a very wide application prospect. The pure graphene and the friction pair can only form a physical adsorption film through Van der Waals force, the adsorption force is small and easy to damage, meanwhile, the pure graphene is easy to agglomerate and difficult to enter the surface of the contact pair, and compared with the traditional lubricating additive such as molybdenum disulfide, the lubricating effect is not ideal. Therefore, increasing the adsorption capacity of graphene and reducing the agglomeration phenomenon as much as possible become a research trend for further improving the lubricating performance of graphene.

The composite material formed by the graphene and the metal oxide loaded on the graphene can show a synergistic effect under certain conditions. The nano particles existing between the graphene layers play a role in separating adjacent graphene sheets and preventing agglomeration. Therefore, the graphene/metal oxide can enter a friction contact surface more easily to form a continuous physical adsorption friction film, so that the direct contact with the surface of a friction pair is prevented, the lubricating capability is improved, and the friction and the abrasion are reduced. The current methods for preparing graphene/metal oxide composite materials are divided into solid-phase methods and liquid-phase methods, and the two methods mainly comprise high-temperature solid-phase methods, sol-gel methods, chemical precipitation methods, hydrothermal methods, direct thermal reduction methods and the like. The high-temperature solid phase method is a method for generating a product through contact, reaction, nucleation and crystal growth reaction between solid interfaces at high temperature, and has the characteristics of low cost, high yield, simple preparation process and the like; its disadvantages include high energy consumption, easy agglomeration of sample, and easy doping of impurities during reaction. The sol-gel method comprises the steps of dissolving an ester compound or metal alkoxide in an organic solvent to form a uniform solution, adding other components, reacting at a certain temperature to form gel, and finally drying to prepare a sample, wherein the sol-gel method has the advantages of simple reaction steps, good uniformity and lower temperature required by reaction; the disadvantages are that the starting materials for the reaction are expensive and partly toxic and that the reaction time is relatively long. The chemical precipitation method is to precipitate a sample by using a precipitant in a solution state, and then dry or roast the sample to obtain a corresponding sample. The hydrothermal method is characterized in that a sample is heated in a closed container to create a high-temperature and high-pressure environment, so that crystals are dissolved and recrystallized in the reaction process, and the sample prepared by the hydrothermal method has the characteristics of good dispersity, high crystallinity of the crystals, medium and low reaction temperature, simple equipment, convenience in operation and the like, but also has the defects of toxicity of a chemical reducing agent in the reaction and the like (the preparation of a polypyrrole/graphene oxide/copper oxide nanorod composite material and the research on the catalytic performance of glucose [ J ] a metal functional material, 2013,20(5):27-31. Wangying, Liyong, Zhujing, and the like, and the research on the graphene/CuO lithium ion battery cathode material is advanced [ J ] a material guide report, 2018,32(21): 38-45.). The direct thermal reduction method overcomes the toxicity problem of a chemical reducing agent, but has the defect that high-pressure reducing gas generated in the heating process influences the quality of products (sunstroke, youth, guo, and the like, preparation and performance of a graphene/tin oxide composite transparent conductive film [ J ]. reported by Harbin Ridgery university, 2017(1), and an improved preparation method ZL application No. 201810434656.2 of a graphene oxide/nano copper oxide composite material.

Disclosure of Invention

The invention aims to provide a preparation method for efficiently preparing a graphene/metal oxide nano lubricating material, so that the graphene/metal oxide nano lubricating material is more in line with the requirements of modern green production, and meanwhile, the structural defects are reduced and the product quality is improved.

The invention provides a method for preparing a low-defect two-dimensional graphene/copper oxide nano composite lubricating material. The method comprises the following steps: (1) carrying out high oxidation treatment on graphite by adopting an improved Hummers method to obtain fully oxidized graphite; (2) mixing the graphite oxide and a soluble salt solution, and carrying out ball milling to ensure that the graphite oxide is fully stripped into graphene oxide, and metal ions are attached to the surface and the layers of the graphene oxide; (3) adding excessive strong base solution into the solution to hydrolyze and directionally polymerize the solution, so that metal ions attached to the surface and the interlayer of the graphene are converted into nano hydroxide; (4) heating the black slurry after the reactionObtaining the graphene/metal oxide nano composite material; (5) the product was washed thoroughly with water and filtered, and dried. (6) Ball-milling and crushing the graphene/copper oxide nano composite material to obtain graphene/copper oxide nano composite material particles. The inventor finds that the method can meet the requirement of green environmental protection better. For example, the conventional preparation method of the graphene composite material is generally a hydrothermal method, but the hydrothermal method has certain defects, such as the toxicity of hydrazine hydrate, which is a chemical reducing agent of the hydrothermal method. The method adopts a direct thermal reduction method, effectively solves the problem of toxicity of the chemical reducing agent, and is more environment-friendly. On the other hand, most of the nano particles in the previous research are attached to the surface of graphene, but the invention finally enables metal ions to be attached to the surface of the graphene and fully intercalated between the surfaces of the graphene through high-energy ball milling of graphite oxide and metal ion mixture. In addition, the traditional thermal reduction process can cause defects such as fold holes and the like of the graphene, so that a large number of structural defects of the graphene nano composite are generated. In order to solve this problem, the present invention proposes a solution to add an excessive amount of strong base to the reaction. The excessive alkali after the reaction can be adsorbed and coated on the surface of the graphene, and can play a role in inhibiting high-pressure reducing gas (such as H) in the subsequent high-temperature reduction process₂O、CO₂CO, etc.) to prevent damage to the structure, ensure that graphene has few defects and exhibits a two-dimensional nanostructure.

According to an embodiment of the present invention, the step (1) further comprises: (1-1) mixing a mixture of sulfuric acid and potassium permanganate with the graphite at 0-5 ℃, and carrying out an oxidation reaction on the obtained mixture at 40-60 ℃ for 2-10 hours; (1-2) mixing the reaction product obtained in the step (1-1) with deionized water, and preserving heat for 0.5-5 hours at the temperature of 60-80 ℃; and (1-3) mixing the reaction product obtained in the step (1-2) with hydrogen peroxide to obtain the graphite oxide.

According to the embodiment of the invention, in the step (1-1), the mass ratio of the sulfuric acid to the potassium permanganate is 2-6: 1, the mass ratio of the mixture of sulfuric acid and potassium permanganate to the graphite is 50-100: 1.

according to the embodiment of the invention, in the step (1-2), the mass ratio of the deionized water to the graphite is 200-1000: 1.

according to an embodiment of the present invention, the step (1) further comprises: (1-4) washing and drying the graphite oxide.

According to an embodiment of the present invention, in the step (1-2), the soluble metal salt may be CuCl₂，CuSO₄And FeCl₃And the like.

According to the embodiment of the invention, in the step (3), the pH value of the solution is controlled to be between 8 and 14.

According to the embodiment of the invention, in the step (4), the thermal reduction reaction temperature is above 100 ℃ until the water is evaporated to dryness to form a black solid.

According to the embodiment of the invention, in the step (5-6), the mixture is mixed in a high-energy ball mill at the rotating speed of 300-1000 rpm for 2-40 hours. .

Drawings

Fig. 1 shows a schematic flow diagram of a method for preparing a low-defect two-dimensional graphene/metal oxide nanocomposite lubricant according to an embodiment of the present invention.

Fig. 2 shows a schematic flow diagram of a method for preparing a graphene/metal oxide nanocomposite lubricant according to another embodiment of the present invention.

Fig. 3 shows a schematic flow diagram of a method for preparing a graphene/metal oxide nanocomposite lubricant according to yet another embodiment of the present invention.

Fig. 4 shows a scanning electron microscope photograph of the graphene/metal oxide nanocomposite lubricant material prepared according to one embodiment of the present invention.

Fig. 5 shows a projection electron microscope picture of the graphene/metal oxide nanocomposite lubricant material prepared according to one embodiment of the present invention.

Fig. 6 shows a graph of the coefficient of friction contrast for an additivated graphene/metal oxide nanocomposite lubricant according to an embodiment of the present invention.

Fig. 7 shows a contrast plot of ink mark profiles with the addition of graphene/metal oxide nanocomposite lubricant and base oil according to one embodiment of the present invention.

Fig. 8 shows a comparative table of XPS elemental composition of graphene/metal oxide nanocomposite lubricant prepared according to an embodiment of the present invention.

Detailed Description

The following describes embodiments of the present invention in detail. The following examples are illustrative only and are not to be construed as limiting the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

The technical solution of the present invention will be further described with reference to the following embodiments and the accompanying drawings.