A method for preparing a macroscopic super-lubricating solid-liquid composite film

Abstract

The present invention relates to a method for preparing a macroscopic superlubricating solid-liquid composite film, which method includes: firstly, preparing an amorphous nanocrystalline multilayer composite film structure by changing the bias voltage and nitrogen flow rate; secondly, adding hydrogen peroxide to a polyethylene glycol and phosphoric acid mixed solution to react in situ to generate a phosphate ester hydrate solution; finally, uniformly dripping, smearing or dipping the mixed solution on the film to obtain a solid-liquid composite film. The method of the present invention is simple and efficient, and the obtained solid-liquid composite film can achieve stable macroscopic superlubricity in an atmospheric environment, providing basic data and ideas for engineering applications.

Description

Technical Field

[0001] The invention belongs to the technical field of tribology and relates to a super-lubricating coating / film, in particular to a method for preparing a macroscopic super-lubricating solid-liquid composite film. Background Art

[0002] Tribology is a science and technology that studies friction, wear and lubrication between two surfaces in relative motion. Friction is closely related to our lives. The study of tribology has promoted the development of science and technology and civilization. Friction is a double-edged sword. Automobile driving and human movement are inseparable from friction, but friction restricts the development of human society. About 30% of the world's primary energy is consumed due to friction every year, about 60% of machine parts fail due to wear, and about 50% of serious accidents in mechanical equipment originate from lubrication failure and excessive wear. Therefore, the research and development of new lubricating materials and technologies is crucial to reducing friction and loss, and is of great significance to the development of modern industry, the improvement of people's lives, and the creation of a green economy.

[0003] As early as in ancient times, people have learned to use lubricating materials and technologies to reduce friction and wear, such as the ancient Egyptians who coated wooden boards with olive oil to carry giant stone statues. To date, lubricating materials can be divided into solid lubricating materials and liquid lubricating materials according to their physical state. Liquid lubricating materials mainly include water-based and oil-based lubricating materials. By virtue of their fluidity, they can enter the gap between friction pairs, play a lubricating role, and can quickly transfer and dissipate heat, becoming one of the most widely used lubrication methods. However, most mechanical parts have low surface strength and hardness, and even under liquid lubrication conditions, they are still prone to wear under high loads. Solid lubricating materials mainly include solid powders, films or block materials, and are mainly used in conditions that are difficult to meet with liquid lubrication, such as vacuum, high temperature and other harsh environments. In particular, solid lubricating films greatly reduce friction without changing the original structural design and materials, becoming a hot spot for research and application. Although solid lubricating films have higher strength and hardness than the base materials of mechanical parts, they are difficult to meet the requirements of long-life service under atmospheric dry friction. Therefore, combining solid lubricating film with lubricating liquid is an effective way to solve the above problems, and the research on macroscopic superlubricating solid-liquid composite film is particularly important. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a macroscopic superlubricating solid-liquid composite film, which has the advantages of both solid and liquid lubricating materials.

[0005] 1. Preparation of superlubricating solid-liquid composite film

[0006] 1) Preparation of amorphous nanocrystalline multilayer composite films

[0007] Titanium target and silicon target were used, and high-power magnetron sputtering was used to generate a Ti substrate layer-TiN intermediate layer-Si transition layer-SiN on the surface of the steel substrate by changing the bias voltage and nitrogen flow rate. x The surface layer consists of an amorphous nanocrystalline multilayer composite film structure;

[0008] The specific steps of preparing amorphous nanocrystalline multilayer composite film structure by high-power magnetron sputtering are as follows: the first step is to clean the contaminants on the surface of the steel block under a bias voltage of -600V; the second step is to sputter a titanium target under a bias voltage of -70V to prepare a Ti substrate layer on the surface of the steel block; the third step is to keep the bias voltage of -70V unchanged, pass 30sccm of nitrogen to prepare a TiN film; the fourth step is to increase the bias voltage to -100V, sputter a silicon target, and grow a Si transition layer on the basis of titanium nitride; the fifth step is to keep the bias voltage of -100V unchanged, pass 50sccm of nitrogen to prepare SiN x film.

[0009] During the above preparation process, the rotation speeds of the target and the workbench were 0.132 m / s and 0.079 m / s respectively, the distance between the target and the workbench was controlled to be 110 mm, and both the titanium target and the silicon target used NdFeB magnets with a magnetic flux of 5000.

[0010] 2) Preparation of superlubricating solid-liquid composite films

[0011] The lubricating liquid obtained by physical ultrasonic mixing is dripped, spread or immersed in the amorphous nanocrystalline multilayer composite film structure prepared in step 1) for 5-10 minutes, taken out and dried, so as to obtain a super lubricating solid-liquid composite film.

[0012] The specific steps of preparing the lubricating fluid by the physical ultrasonic mixing method are as follows: polyethylene glycol, phosphoric acid, and hydrogen peroxide in a mass ratio of (1-1.2):(1-1.2):(0.2-0.4) are weighed, the polyethylene glycol and phosphoric acid are first subjected to ultrasonic mixing for 10-15 minutes, and then the hydrogen peroxide is added to the mixed solution and ultrasonic treatment is continued for 30-40 minutes to promote the reaction of polyethylene glycol and phosphoric acid to generate a phosphate-like lubricating fluid.

[0013] 2. Characterization of the structure of superlubricating solid-liquid composite films

[0014] Figure 1 This is a transmission electron microscope image of the amorphous nanocrystalline multilayer composite film structure prepared by the present invention. It can be seen that by controlling the bias voltage and nitrogen flow rate during the magnetron sputtering process, an amorphous nanocrystalline multilayer composite film structure as shown in the figure can be obtained.

[0015] Figure 2 The lubricating fluid prepared by the present invention 1H NMR spectrum. Compared with the NMR spectrum of polyethylene glycol, the newly prepared lubricating fluid has a phosphate-like structure, which acts as a shear layer to reduce friction and achieve superlubricity.

[0016] 3. Performance evaluation of superlubricating solid-liquid composite films

[0017] The solid-liquid composite film obtained by the present invention was fixed on a friction machine, and a 440C ball with a diameter of 6 mm was selected as a dual ball for CSM friction test. The experimental parameters were set as follows: friction load of 3 N, rotation speed of 500 rpm, radius of 4 mm, atmospheric atmosphere, friction time of 30 min, room temperature friction, and the following results were obtained: Figure 3 The CSM friction curve is shown. During the friction process, due to the physical adsorption of polyethylene glycol on the surface of the friction pair, a tribochemical reaction occurs on the two contact surfaces to generate a quasi-phosphate ester in situ. The generated quasi-phosphate ester acts as a new oil film, which can block the direct contact between the film and the dual ball, thereby generating a lower shear force between the interfaces. The solid-liquid composite film obtained by the present invention has almost no running-in period during the friction process, and can achieve stable superlubricity with a friction coefficient of about 0.005.

[0018] In summary, the present invention has the following advantages:

[0019] 1. The present invention uses a high-power magnetron sputtering method to prepare a thin film of a composite multilayer structure of amorphous nanocrystals, and then obtains a solid-liquid composite thin film by uniformly dripping, applying or immersing a mixed lubricating liquid. The method is not only simple but also highly efficient.

[0020] 2. In the solid-liquid composite film obtained by the present invention, the polyethylene glycol in the lubricating liquid is physically adsorbed on the contact interface of the dual balls during the friction process, generating a layer of polymer brush-like substances, thereby blocking the direct contact between the friction pairs. At the same time, during the friction process, since the lubricating liquid can react in situ to generate phosphate-like esters under the action of hydrogen peroxide, the generated phosphate-like esters can serve as a new oil film on the surface of the friction pair to block the direct contact between the film and the dual balls, thereby achieving macroscopic superlubrication.

[0021] 3. The solid-liquid composite film obtained by the present invention can achieve macroscopic superlubrication in a stable atmospheric environment, providing basic data and ideas for engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a 20nm transmission electron microscope image of the amorphous nanocrystalline multilayer composite film structure prepared by the present invention.

[0023] Figure 2 The lubricating fluid prepared by the present invention 1 H NMR spectrum.

[0024] Figure 3This is the friction coefficient curve of the solid-liquid composite film prepared by the present invention. DETAILED DESCRIPTION

[0025] The preparation method of the macroscopic superlubricating solid-liquid composite film of the present invention and the friction performance are described in detail below through specific examples. Example

[0026] (1) Preparation before coating: The steel block was ultrasonically cleaned in acetone and ethanol for 15 min respectively, and then dried in a vacuum oven at 50 °C for 10 min. The dried steel block was mounted on the sample holder, and the distance between the sample holder and the target was controlled to be 110 mm.

[0027] (2) Preparation of amorphous nanocrystalline multilayer composite film structure: The chamber is evacuated to a vacuum degree better than 5×10 -3 Pa, 150 sccm of Ar was introduced, and sputtering was performed at a bias of -500 V for 30 min to remove oxides and impurities on the target surface. During the entire deposition process, the gas pressure in the chamber was always maintained at 1.1 Pa. Titanium targets and silicon targets were used, and high-power magnetron sputtering was used. In the first step, the contaminants on the surface of the steel block were cleaned at a bias of -600V; in the second step, the titanium target was sputtered at a bias of -70V to prepare a Ti substrate layer on the surface of the steel block; in the third step, the bias of -70V was kept unchanged, 30sccm of nitrogen was introduced, and TiN film was prepared; in the fourth step, the bias was increased to -100V, and a Si transition layer was grown on the basis of titanium nitride; in the fifth step, the bias of -100V was kept unchanged, and 50sccm of nitrogen was introduced to prepare SiN x film( Figure 1 ).

[0028] (3) Preparation of lubricating fluid: The lubricating fluid was prepared by physical ultrasonic mixing method as follows: polyethylene glycol, phosphoric acid and hydrogen peroxide were weighed in a mass ratio of 1:1:0.2. The polyethylene glycol and phosphoric acid were first ultrasonically mixed for 10 min, and then hydrogen peroxide was added to the mixed solution and ultrasonic treatment was continued for 30 min. The addition of hydrogen peroxide can promote the reaction between polyethylene glycol and phosphoric acid to generate phosphate esters ( Figure 2 ).

[0029] (4) Preparation method of solid-liquid composite film: The lubricating liquid obtained by ultrasonic mixing is dripped, applied or immersed in the prepared amorphous nanocrystalline composite multilayer film structure for 5 minutes, taken out and dried to obtain a solid-liquid composite film. This film can be directly rubbed against a steel ball to achieve stable superlubrication without a running-in period.

[0030] (5) Friction performance test: Using CSM, a 440C steel ball and a solid-liquid composite film based on amorphous nanocrystalline composite multilayer film were selected as the friction pair. The friction coefficient was measured in an atmospheric environment with a load of 3N and a humidity of 30-40%. Figure 3 ). The prepared solid-liquid composite film samples can reach a superlubricity state in the atmospheric environment.

Claims

1. A method for preparing a macroscopic superlubricating solid-liquid composite film, characterized in that: The following steps are involved: 1) Preparation of amorphous nanocrystalline multilayer composite films Titanium target and silicon target were used, and high-power magnetron sputtering was used to generate a Ti substrate layer-TiN intermediate layer-Si transition layer-SiN on the surface of the steel substrate by changing the bias voltage and nitrogen flow rate. x The surface layer consists of an amorphous nanocrystalline multilayer composite film structure; The specific steps of preparing amorphous nanocrystalline multilayer composite film structure by high-power magnetron sputtering are as follows: the first step is to clean the contaminants on the surface of the steel block under a bias voltage of -600V; the second step is to sputter a titanium target under a bias voltage of -70V to prepare a Ti substrate layer on the surface of the steel block; the third step is to keep the bias voltage of -70V unchanged, pass 30sccm of nitrogen to prepare a TiN film; the fourth step is to increase the bias voltage to -100V, sputter a silicon target, and grow a Si transition layer on the basis of titanium nitride; the fifth step is to keep the bias voltage of -100V unchanged, pass 50sccm of nitrogen to prepare SiN x Thin film; during the preparation process, the rotation speeds of the target and the workbench were 0.132 m / s and 0.079 m / s respectively, the distance between the target and the workbench was 110 mm, and both the titanium target and the silicon target used NdFeB magnets with a magnetic flux of 5000; 2) Preparation of superlubricating solid-liquid composite films The lubricating liquid obtained by physical ultrasonic mixing is dripped, smeared or immersed in the amorphous nanocrystalline multilayer composite film structure prepared in step 1) for 5-10 minutes, taken out and dried, so as to obtain a super lubricating solid-liquid composite film; The specific steps of preparing the lubricating fluid by the physical ultrasonic mixing method are as follows: polyethylene glycol, phosphoric acid, and hydrogen peroxide in a mass ratio of (1-1.2):(1-1.2):(0.2-0.4) are weighed, the polyethylene glycol and phosphoric acid are first subjected to ultrasonic mixing for 10-15 minutes, and then the hydrogen peroxide is added to the mixed solution and ultrasonic treatment is continued for 30-40 minutes to promote the reaction of polyethylene glycol and phosphoric acid to generate a phosphate-like lubricating fluid.

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