阅读说明：本技术 一种润滑剂及其制备方法和应用 (Lubricant as well as preparation method and application thereof ) 是由 高原 吴彤 潘奘 赵省良 王伟 王快社 于 2021-01-16 设计创作，主要内容包括：本发明公开了一种润滑剂及其制备方法和应用,本发明润滑剂的结构为核壳结构,其中,核心为二硫化钼颗粒,外壳为包覆于二硫化钼颗粒外部的二氧化硅。制备本发明的润滑剂的步骤包括：将二硫化钼加入一种强氧化性溶液中,连续搅拌一定时间,再进行洗涤和干燥；向处理过后的二硫化钼中加入去离子水,超声分散,粗配成悬浊液,再与无水乙醇混合,加入正硅酸乙酯、氨水后在一定温度下开始反应,电磁搅拌下反应数小时；分离上述反应产物,用无水乙醇洗数次,再用去离子水洗数次,然后真空干燥,即得所述润滑剂。本发明制备的润滑剂可以作为热挤压等金属材料加工润滑剂,本发明方法具有工艺简单、原料易得、成本低、润滑性能好等特点。(The invention discloses a lubricant, a preparation method and application thereof. The steps for preparing the lubricant of the present invention include: adding molybdenum disulfide into a strong oxidizing solution, continuously stirring for a certain time, and then washing and drying; adding deionized water into the treated molybdenum disulfide, performing ultrasonic dispersion, roughly preparing a suspension, mixing the suspension with absolute ethyl alcohol, adding tetraethoxysilane and ammonia water, starting reaction at a certain temperature, and reacting for several hours under electromagnetic stirring; and separating the reaction product, washing the reaction product with absolute ethyl alcohol for a plurality of times, washing the reaction product with deionized water for a plurality of times, and then drying the reaction product in vacuum to obtain the lubricant. The lubricant prepared by the method can be used as a lubricant for processing metal materials such as hot extrusion and the like, and the method has the characteristics of simple process, easily obtained raw materials, low cost, good lubricating property and the like.)

1. The lubricant is characterized by comprising a core and a shell, wherein the core is a molybdenum disulfide particle, and the shell is silicon dioxide coated outside the molybdenum disulfide particle.

2. The lubricant of claim 1, wherein the volume percent of the molybdenum disulfide particles is 40-60%, the volume percent of the silica is 60-40%, and the lubricant has a particle size of 0.2-0.4 μm.

3. A method for preparing the lubricant according to claim 1 or 2, comprising the steps of:

preparing a silica shell on the surface of the molybdenum disulfide particles with hydroxylated surfaces to obtain the lubricant.

4. The preparation method according to claim 3, wherein the molybdenum disulfide is added into the piranha solution for reaction, and after the reaction is finished, the molybdenum disulfide particles with hydroxylated surfaces are obtained by washing and drying.

5. The process according to claim 4, wherein the reaction time of the molybdenum disulfide with the piranha solution is 5-10min, and the stirring is continued during the reaction.

6. The method of claim 3, wherein the step of preparing the silica shell on the surface of the surface-hydroxylated molybdenum disulfide particles comprises:

mixing the suspension of the molybdenum disulfide particles with hydroxylated surfaces with ethanol, and adding tetraethoxysilane and ammonia water for reaction; and after the reaction is finished, carrying out solid-liquid separation, and washing and drying the obtained solid to obtain the lubricant.

7. The method according to claim 6, wherein the volume ratio of ethanol to water in the suspension of the surface-hydroxylated molybdenum disulfide particles is (2-5): 1, the dosage proportion of the molybdenum disulfide particles with hydroxylated surfaces, ammonia water and ethyl orthosilicate satisfies the following relationship: and correspondingly adding 20-40 ml of ammonia water and 15-35 ml of ethyl orthosilicate into each gram of the surface hydroxylated molybdenum disulfide particles, wherein the mass percentage of the solute of the ammonia water is 25% -28%.

8. The method according to claim 6, wherein the reaction temperature is room temperature and the reaction time is 6 to 24 hours.

9. The method according to claim 6, wherein the obtained solid is dried under vacuum to remove moisture.

10. Use of the lubricant according to claim 1 or 2 for extrusion lubrication.

Technical Field

The invention belongs to the technical field of lubricating materials, and particularly relates to a lubricant, and a preparation method and application thereof.

Background

Molybdenum disulfide is taken as a typical transition metal binary compound, has a graphene-like structure, and Mo and S atoms in a layer form a covalent bond, so that the structure is stable. With the rapid development of science and technology, MoS₂Nanomaterials have important applications in many areas, such as: lubricants, catalysts, coating materials, electron probes, and the like; in addition, MoS₂Is a P-type narrow-band-gap semiconductor nano material, and is also widely applied to the aspects of solar cells, photoelectric devices and the like. Molybdenum disulfide overcomes the defects of the zero-band-gap graphene material by virtue of unique structural properties, and simultaneously has a plurality of advantages, and has huge potential in a plurality of fields, but the research of the novel molybdenum disulfide nano material has a plurality of scientific problems to be solved.

MoS₂The lubricating oil is widely applied to lubrication as a solid lubricant due to good lubricating property, but is difficult to play a role in lubrication of a plurality of metal material processing techniques due to easy oxidation failure at high temperature.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a lubricant, a preparation method and application thereof, so as to solve the problem that molybdenum disulfide is easy to oxidize in the lubricant.

In order to solve the technical problems, the invention is realized by the following technical scheme.

The lubricant is of a core-shell structure and comprises a core and a shell, wherein the core is molybdenum disulfide particles, and the shell is silicon dioxide coated outside the molybdenum disulfide particles.

Preferably, in the lubricant, the volume percentage of the molybdenum disulfide particles is 40-60%, the volume percentage of the silicon dioxide is 60-40%, and the particle size of the lubricant is 0.2-0.4 μm.

The preparation method of the lubricant comprises the following steps:

preparing a silica shell on the surface of the molybdenum disulfide particles with hydroxylated surfaces to obtain the lubricant.

Preferably, the molybdenum disulfide is added into the piranha solution for reaction, and after the reaction is finished, the molybdenum disulfide is washed and dried to obtain the surface hydroxylated molybdenum disulfide particles.

Preferably, the reaction time of the molybdenum disulfide and the piranha solution is 5-10min, and the molybdenum disulfide and the piranha solution are continuously stirred in the reaction process.

Preferably, the process for preparing a silica shell on the surface of the surface hydroxylated molybdenum disulfide particles comprises:

mixing the suspension of the molybdenum disulfide particles with hydroxylated surfaces with ethanol, and adding tetraethoxysilane and ammonia water for reaction; and after the reaction is finished, carrying out solid-liquid separation, and washing and drying the obtained solid to obtain the lubricant.

Preferably, the volume ratio of the ethanol to the water in the suspension of the surface hydroxylated molybdenum disulfide particles is (2-5): 1, the dosage proportion of the molybdenum disulfide particles with hydroxylated surfaces, ammonia water and ethyl orthosilicate satisfies the following relationship: and correspondingly adding 20-40 ml of ammonia water and 15-35 ml of ethyl orthosilicate into each gram of the surface hydroxylated molybdenum disulfide particles, wherein the mass percentage of the solute of the ammonia water is 25-28%.

Preferably, the reaction temperature of the molybdenum disulfide particles subjected to surface hydroxylation, ethanol, ethyl orthosilicate and ammonia water is room temperature, and the reaction time is 6-24 hours.

Preferably, the resulting solid is dried under vacuum to remove water.

The lubricant of the invention can be applied to extrusion lubrication.

The invention has the following beneficial effects:

the structure of the lubricant is a core-shell structure, wherein the core is molybdenum disulfide particles, the shell is silicon dioxide coated outside the molybdenum disulfide particles, and the friction coefficient of the lubricant is reduced and the compression resistance and wear resistance are enhanced through the coating of the silicon dioxide on the molybdenum disulfide particles and the synergistic effect of the silicon dioxide and the nano molybdenum disulfide; and the melting point of the silicon dioxide is high, and the coated molybdenum disulfide is not easy to oxidize, so that the molybdenum disulfide particles in the lubricant are not easy to oxidize and lose efficacy at high temperature, and can play a good lubricating role. In conclusion, the lubricant disclosed by the invention solves the problem of oxidative decomposition of molybdenum disulfide under a high-temperature working condition.

In the preparation method of the lubricant, the silicon dioxide shell is prepared on the surface of the molybdenum disulfide particles with hydroxylated surfaces, so that the silicon dioxide is easier to coat the surface of the molybdenum disulfide particles. In the preparation method, the composite material generated by the reaction does not need to be sintered at high temperature, so that the oxidation failure of the molybdenum disulfide during roasting is prevented. The silicon dioxide is used for coating the surface of the molybdenum disulfide, so that the molybdenum disulfide is prevented from decomposing and losing efficacy at high temperature in the processing process of metal materials such as hot extrusion.

Further, adding molybdenum disulfide into the piranha solution for reaction, and washing and drying after the reaction is finished to obtain the surface hydroxylated molybdenum disulfide particles. The piranha solution is a mixed solution of hydrogen peroxide and concentrated sulfuric acid, has strong oxidizability, and can remove most impurities on the surface of the molybdenum disulfide and hydroxylate the surface of the molybdenum disulfide by treating the surface of the molybdenum disulfide with the piranha solution.

Further, the process for preparing the silica shell on the surface of the surface-hydroxylated molybdenum disulfide particles comprises the following steps: mixing the suspension of the molybdenum disulfide particles with hydroxylated surfaces with ethanol, and adding tetraethoxysilane and ammonia water for reaction; and after the reaction is finished, carrying out solid-liquid separation, and washing and drying the obtained solid to obtain the lubricant. The tetraethoxysilane can be hydrolyzed and condensed under the acidic and alkaline environment, and the hydrolysis and condensation reaction are a pair of competitive reactions. Under the same concentration and acidic condition, the hydrolysis speed is higher than the polycondensation speed; under alkaline conditions, the rate of polycondensation is greater than the rate of hydrolysis. The invention selects alkaline condition, and provides hydroxide radical by ammonia water. The low reaction temperature, the alkaline reaction environment, the low ethyl orthosilicate concentration and the high hydrophilicity of the nucleation interface are favorable for the non-spontaneous nucleation process, so that the nucleation is formed on the existing interface.

Further, the volume ratio of the ethanol to the water in the suspension of the surface hydroxylated molybdenum disulfide particles is (2-5): 1, the dosage proportion of the molybdenum disulfide particles with hydroxylated surfaces, ammonia water and ethyl orthosilicate satisfies the following relationship: and correspondingly adding 20-40 ml of ammonia water and 15-35 ml of ethyl orthosilicate into each gram of the surface hydroxylated molybdenum disulfide particles, wherein the mass percentage of the solute of the ammonia water is 25-28%. Only one part of the raw material of the tetraethoxysilane participates in the reaction, the utilization rate is greatly changed along with the ratio of the feeding concentration of the tetraethoxysilane, and if the feeding concentration is high, the loss rate of the tetraethoxysilane is high and the utilization rate is lower.

Drawings

FIG. 1 is a field emission electron microscope (TEM) image of the silica-coated molybdenum disulfide composite prepared in example 1,

FIG. 2 is a field emission electron microscope (TEM) image of the silica-coated molybdenum disulfide composite prepared in example 2,

fig. 3 is a field emission projection electron microscope (TEM) image of the silica-coated molybdenum disulfide composite prepared in example 3.

Detailed Description

The invention is further described below with reference to the figures and examples.

The preparation method of the lubricant comprises the following steps:

(1) adding molybdenum disulfide into the piranha solution, continuously stirring for 5-10min, and then washing and drying to obtain surface hydroxylated molybdenum disulfide particles;

(2) ultrasonically dispersing the surface-hydroxylated molybdenum disulfide particles obtained in the step (1) in deionized water to prepare a suspension, mixing the suspension with absolute ethyl alcohol, adding tetraethoxysilane and ammonia water, starting reaction at a certain temperature, and reacting for 6-24 hours under electromagnetic stirring;

(3) and (3) after the reaction in the step (2) is finished, separating the reaction product in the step (2), washing the reaction product with absolute ethyl alcohol and deionized water in sequence, and then carrying out vacuum drying to obtain the silicon dioxide-coated molybdenum disulfide composite material (namely the lubricant of the invention).

In the piranha solution adopted by the invention, the volume ratio of concentrated sulfuric acid to hydrogen peroxide is 3: 1. the volume ratio of the ethanol to the deionized water in the step (2) is 2: 1, the dosage proportion of the molybdenum disulfide, ammonia water and ethyl orthosilicate in the step (2) is 1 g: 20-40 ml: 15-35 ml. The reaction temperature in the step (2) is 25 ℃, and the reaction time is 6-24 hours.

According to the invention, after the molybdenum disulfide is pretreated by the strong oxidation solution, the surface of the molybdenum disulfide is hydroxylated and is easier to coat. The silicon dioxide coated molybdenum disulfide composite material prepared by the invention has better dispersibility in a lubricant and is not easy to agglomerate. The composite material generated by the reaction does not need to be sintered at high temperature, so that the oxidation failure of the molybdenum disulfide during roasting is prevented. The silicon dioxide is used for coating the surface of the molybdenum disulfide, so that the molybdenum disulfide is prevented from decomposing and losing efficacy at high temperature in the processing process of metal materials such as hot extrusion. The coated molybdenum disulfide has good dispersibility in the lubricant, stable property and difficult decomposition.

When the lubricant is used as an additive in other lubricants, the molybdenum disulfide particles are wrapped by the silicon dioxide, so that the dispersibility of the molybdenum disulfide in the lubricant is promoted, the agglomeration phenomenon is avoided, the lubricant can be better applied, and the integral high-temperature service capacity of the lubricant can be improved.

Example 1

The preparation method of the lubricant of the embodiment comprises the following steps:

(1) adding 0.003g of molybdenum disulfide powder into the prepared piranha solution, continuously stirring for 5min, washing and drying;

(2) adding 15ml of deionized water into the molybdenum disulfide treated in the step (1), performing ultrasonic dispersion for 10min to prepare a suspension roughly, mixing the suspension with 30ml of absolute ethanol, adding 0.3ml of tetraethoxysilane and 0.5ml of ammonia water, starting reaction at 25 ℃, and reacting for 16 hours under electromagnetic stirring;

(3) and (3) separating the reaction product, washing the reaction product with absolute ethyl alcohol for 2 times, then washing the reaction product with deionized water for 2 times, and then drying the reaction product in vacuum to obtain the silicon dioxide-coated molybdenum disulfide composite material (namely the lubricant of the invention).

Fig. 1 is a transmission electron microscope image of the silica-coated molybdenum disulfide composite material prepared in example 1 of the method of the present invention. Molybdenum disulfide powder is coated with SiO with the thickness of about 30nm₂The coating layer is compact and continuous, and the thickness is relatively uniform.

Example 2

The preparation method of the lubricant of the embodiment comprises the following steps:

(1) adding 0.003g of molybdenum disulfide powder into the prepared piranha solution, continuously stirring for 5min, washing and drying;

(2) adding 10ml of deionized water into the molybdenum disulfide treated in the step (1), performing ultrasonic dispersion for 10min to prepare a suspension roughly, mixing the suspension with 20ml of absolute ethanol, adding 0.8ml of tetraethoxysilane and 0.6ml of ammonia water, starting reaction at 25 ℃, and reacting for 6 hours under electromagnetic stirring;

(3) and (3) separating the reaction product, washing the reaction product with absolute ethyl alcohol for 2 times, then washing the reaction product with deionized water for 2 times, and then drying the reaction product in vacuum to obtain the silicon dioxide-coated molybdenum disulfide composite material (namely the lubricant of the invention).

Fig. 2 is a transmission electron microscope image of the silica-coated molybdenum disulfide composite material prepared in example 2 of the method of the present invention. The coating layer is compact and continuous, and the thickness is uniform. And the coating layer is relatively thin, so that the morphological characteristics of the molybdenum disulfide are maintained.

Example 3

The preparation method of the lubricant of the embodiment comprises the following steps:

(1) adding 0.02g of molybdenum disulfide powder into the prepared piranha solution, continuously stirring for 10min, washing and drying;

(2) adding 20ml of deionized water into the molybdenum disulfide treated in the step (1), performing ultrasonic dispersion for 10min to prepare a suspension roughly, mixing the suspension with 40ml of absolute ethanol, adding 2.0ml of tetraethoxysilane and 1.0ml of ammonia water, starting reaction at 25 ℃, and reacting for 24 hours under electromagnetic stirring;

(3) and (3) separating the reaction product, washing the reaction product with absolute ethyl alcohol for 2 times, then washing the reaction product with deionized water for 2 times, and then drying the reaction product in vacuum to obtain the silicon dioxide-coated molybdenum disulfide composite material (namely the lubricant of the invention).

Fig. 3 is a transmission electron microscope image of the silica-coated molybdenum disulfide composite material prepared in example 3 of the method of the present invention. The coating layer is relatively thin, and the thickness is uniform and continuous. The morphological characteristics of the molybdenum disulfide are maintained.