CN102093081A - Adaptive graphite-like carbon-based film material for mechanical seal and preparation method thereof - Google Patents

Abstract

The invention discloses an adaptive graphite-like carbon-based thin film material for mechanical sealing and a preparation method thereof. The material is sequentially composed of a matrix material, an underlying adhesive layer with a thickness of 0.1-0.2 microns and a graphite-like carbon surface layer with a thickness of 1.5-2.5 microns. The hardness of the material of the present invention is as high as 25GPa, and its wear life is more than 2 orders of magnitude higher than that of the uncoated substrate. The friction coefficient is stable at 0.04-0.06 under dry friction and water lubrication conditions, and it has stable low friction and multi-environment friction under variable working conditions Wear Adaptive Features. It can be used for self-lubrication and life extension treatment of moving parts such as ceramic mechanical seals such as sealing rings, shaft sleeves and water-lubricated ceramic bearings.

Description

Self-adaptive graphite-like carbon-based film material for mechanical seal and preparation method thereof

technical field

The invention relates to a self-adaptive graphite-like carbon-based film material and a preparation method thereof, specifically obtaining a graphite-like carbon-based self-lubricating film on the surface of a mechanical ceramic seal, belonging to the field of surface treatment.

Background technique

In order to reduce or reduce the friction, wear, vibration, impact, noise, poor reliability and short life of various mechanical seal friction pairs caused by movement, in the manufacture of key parts of mechanical seals, the surface film technology of friction pairs has gradually become An important way to improve the service performance of the mechanical seal system. Variable working conditions (frequent start and stop, low speed/high speed, boundary lubrication/near-dry friction, etc.) are the main characteristics of the operation of modern mechanical seal systems, and are also one of the key issues restricting their life and reliability. With the development of modern mechanical sealing systems towards high efficiency and energy saving, diversified working conditions, and ultra-long service life requirements, its surface film processing technology is facing the development trend of the following two aspects: ① The surface film is required to have ultra-high hardness and ultra-high toughness And ultra-low friction and excellent anti-wear performance; ②The surface film is required to have certain adaptive characteristics of variable working conditions and excellent self-lubricating characteristics under boundary lubrication conditions. Among them, surface carbon-based films (such as diamond films, diamond-like films, graphite-like films, etc.) have been widely valued for their excellent anti-friction, anti-wear and corrosion resistance properties in fluids. In terms of processing carbon-based films on the surface of mechanical seals, currently only patent CN101133184A uses chemical vapor deposition technology to coat diamond films on the surface of mechanical seals or bearings. However, there are high costs, rough surface of the film layer, and difficulty in polishing ultra-high hardness diamond films. Big and other shortcomings.

Graphite-like carbon film is a newly developed new type of solid lubricating material, which has the advantages of smoothness, high hardness, low friction and long life, and is an ideal material for surface modification of ceramic seals. The advantages of ceramic seals and plain bearings are their high wear resistance and low coefficient of friction in wet or chemically aggressive environments. However, under dry running and insufficient lubrication conditions, the performance of these components is not satisfactory. If a high-hardness graphite film can be coated on the surface of ceramic seals, it will significantly improve its reliable life under variable working conditions (frequent start and stop, low speed/high speed, boundary lubrication/near-dry friction, etc.), making its Under the conditions of mixed friction and dry operation, stable low friction is obtained and certain multi-environment adaptive characteristics are displayed. At present, there is no relevant patent report on the self-lubricating modification of self-lubricating ceramic parts using self-adaptive graphite-like carbon film.

Contents of the invention

The purpose of the present invention is to provide a mechanical seal surface self-adaptive film with high hardness, high wear resistance and self-lubricating performance under dry friction or water lubrication and its surface processing method, so as to improve ceramic mechanical seals Problems such as poor reliability caused by parts under variable working conditions such as initial run-in, frequent start and stop, low speed/high speed, and short-term overload.

To achieve the above object, the technical solution provided by the invention is:

An adaptive graphite-like carbon-based film material for mechanical seals, which is sequentially composed of a base material, an underlying adhesive layer with a thickness of 0.1-0.2 microns, and a graphite-like carbon surface layer with a thickness of 1.5-2.5 microns; the base material is selected from From a kind of in cemented carbide, silicon carbide and silicon nitride ceramics, the bottom bonding layer is Ti or Si; the sp2 bond content in the C-C structure of graphite in the described graphite-like carbon surface layer is 60 ~80%, which belongs to the typical hydrogen-free graphitic carbon structure.

A method for preparing an adaptive graphite-like carbon-based film material for mechanical seals, characterized in that the steps of the method are: (1) cleaning the base material by plasma sputtering, placing the base material in a magnetron sputtering vapor deposition system, and performing argon plasma Bulk sputtering cleaning, the flow rate of argon gas is 50-70sccm, the bias voltage is 800-1000V, and the processing time is 30-40min; (2) Ti or Si bonding layer is deposited by magnetron sputtering, and the metal Ti target or Si target is Cathode, the working gas is argon, the control power is 300~500W, the bias voltage is -300V, and the processing time is 30~50min; (3) Magnetron sputtering deposits graphite-like carbon film. During the deposition process, the vacuum chamber The bottom vacuum is 5×10-4Pa, the discharge pressure is 0.5Pa, the high-purity graphite target is the cathode, the target current is 1-1.2A, the bias voltage is 300-500V applied to the substrate, and the deposition time is 120-150min. Obtain high-hardness adaptive graphite-like carbon-based thin film materials.

Adopt Raman spectrum, X-ray photoelectron energy spectrometer and high-resolution projection electron microscope (HRTEM) to test the prepared graphitic carbon film of the present invention, the sp2 bond content in the C-C structure of graphitic class in the graphitic carbon surface layer is 60 ~80%, which belongs to the typical hydrogen-free graphitic carbon structure. HRTEM analysis shows that its structure is: there are many nano-graphite clusters and diamond particles with a particle size of 3-8nm dispersed in the amorphous carbon matrix, which is the main reason for the high hardness of the film (25GPa).

Carry out ball-on-disk reciprocating friction and wear test (as shown in Table 1) in atmosphere (HR=30 ± 5%) and water respectively to the high-hardness graphite-like carbon-based film prepared in the embodiment: the result shows that this film material is under dry friction condition Under the condition of water lubrication, the friction coefficient can be stabilized at about 0.06, and under the condition of water lubrication, the friction coefficient can reach 0.04. Compared with uncoated ceramic matrix silicon nitride, silicon carbide and cemented carbide, the wear resistance of the high-hardness graphite-like carbon-based film obtained by the present invention is improved by 1-2 orders of magnitude, and its performance under dry friction and water lubrication The friction coefficient and wear rate are not much different, indicating that it has excellent low friction and stable solid lubrication characteristics under variable working conditions, highlighting certain multi-environmental friction and wear adaptive characteristics. The high-hardness graphite-like carbon-based film material of the present invention has excellent variable-condition self-lubricating behavior (dry friction/water environment) and high wear resistance, and can be used for ceramic mechanical seals such as seal rings, shaft sleeves and water-lubricated ceramic bearings, etc. Self-lubricating and life-extending treatment of moving parts.

Table 1

Detailed ways

Example 1:

The self-adaptive graphite-like carbon-based film material on the surface of silicon nitride for mechanical sealing is composed of a silicon nitride substrate, an underlying Si bonding layer with a thickness of 0.2 microns, and a graphite-like carbon surface layer with a thickness of 1.5 microns.

The treatment process of high-hardness graphite-like carbon-based film materials on the surface of silicon nitride is carried out according to the following steps: (1) Plasma sputtering cleans the silicon nitride substrate, puts the substrate in a magnetron sputtering vapor deposition system, and conducts argon plasma Sputtering cleaning, the argon gas flow rate is 60sccm, the bias voltage is 1000V, and the processing time is 30min; (2) magnetron sputtering deposits the Si bonding layer, the Si target is the cathode, the working gas is argon, and the power of the radio frequency power supply is controlled as 500W, the applied bias voltage of the substrate is 500V, and the processing time is 50min; (3) Magnetron sputtering deposits graphite-like carbon film. During the deposition process, the background vacuum of the vacuum chamber is 5×10-4Pa, and the discharge pressure is 0.5Pa. The high-purity graphite target is the cathode, the target current is 1.2A, the substrate is biased at 300V, and the deposition time is 150min. Finally, a high-hardness adaptive graphite-like carbon-based film material is obtained on the surface of the silicon nitride substrate.

Example 2:

The self-adaptive graphite-like carbon-based film material on the surface of silicon carbide for mechanical seals is sequentially composed of a silicon carbide substrate, an underlying Si bonding layer with a thickness of 0.2 microns, and a graphite-like carbon surface layer with a thickness of 2 microns.

The treatment process of high-hardness graphite-like carbon-based film materials on the surface of silicon carbide is carried out according to the following steps: (1) plasma sputtering to clean the silicon carbide substrate, place the substrate in a magnetron sputtering vapor deposition system, and perform argon plasma sputtering Cleaning, the argon gas flow rate is 60sccm, the bias voltage is 1000V, and the processing time is 30min; (2) Magnetron sputtering deposits the Si bonding layer, the Si target is the cathode, the working gas is argon, and the power of the radio frequency power supply is controlled to 500W, The bias voltage applied to the substrate was 500V, and the processing time was 50min; (3) The graphite-like carbon film was deposited by magnetron sputtering. During the deposition process, the background vacuum of the vacuum chamber was 5×10-4Pa, and the discharge pressure was 0.5Pa. The graphite target is the cathode, the target current is 1.2A, the substrate is biased at 300V, and the deposition time is 240min. Finally, a high-hardness adaptive graphite-like carbon-based film material is obtained on the surface of the silicon carbide substrate.

Example 3:

The self-adaptive graphite-like carbon-based film material on the surface of WC cemented carbide for mechanical seals is composed of a cemented carbide substrate, a bottom Ti bonding layer with a thickness of 0.1 microns, and a graphite-like carbon surface layer with a thickness of 2 microns.

The treatment process of high-hardness graphite-like carbon-based film materials on the surface of WC cemented carbide is carried out according to the following steps: (1) Plasma sputtering cleans the silicon carbide substrate, puts the substrate in a magnetron sputtering vapor deposition system, and conducts argon plasma Sputtering cleaning, the argon gas flow rate is 60sccm, the bias voltage is 1000V, and the processing time is 30min; (2) Ti bonding layer is deposited by magnetron sputtering, the metal Ti target is the cathode, the working gas is argon, and the target current is controlled as 2.0A, the applied bias voltage of the substrate is 500V, and the processing time is 20min; (3) Magnetron sputtering deposits graphite-like carbon film. During the deposition process, the background vacuum of the vacuum chamber is 5×10-4Pa, and the discharge pressure is 0.5Pa , the high-purity graphite target is the cathode, the target current is 1.2A, the substrate is biased at 300V, and the deposition time is 240min. Finally, a high-hardness adaptive graphite-like carbon-based film material is obtained on the surface of the silicon carbide substrate.

Claims (2)

1. A self-adaptive graphite-like carbon-based film material for mechanical sealing, which is successively composed of a base material, a thickness of 0.1 to 0.2 microns, an underlying adhesive layer, and a thickness of 1.5 to 2.5 microns of graphite-like carbon surface layer; the substrate The material is selected from one of cemented carbide, silicon carbide and silicon nitride ceramics, the bottom bonding layer is Ti or Si; the sp2 bond content in the graphite-like C-C structure in the graphite-like carbon surface layer It is 60-80%, which belongs to the typical hydrogen-free graphitic carbon structure. 2. the preparation method of coating as claimed in claim 1 is characterized in that this method step is: (1) plasma sputtering cleans base material, base material is placed in magnetron sputtering vapor deposition system, carries out argon plasma Bulk sputtering cleaning, the flow rate of argon gas is 50-70sccm, the bias voltage is 800-1000V, and the processing time is 30-40min; (2) Ti or Si bonding layer is deposited by magnetron sputtering, and the metal Ti target or Si target is Cathode, the working gas is argon, the control power is 300~500W, the bias voltage is -300V, and the processing time is 30~50min; (3) Magnetron sputtering deposits graphite-like carbon film. During the deposition process, the vacuum chamber The bottom vacuum is 5×10-4Pa, the discharge pressure is 0.5Pa, the high-purity graphite target is the cathode, the target current is 1-1.2A, the bias voltage is 300-500V applied to the substrate, and the deposition time is 120-150min. Obtain high-hardness adaptive graphite-like carbon-based thin film materials.