Preparation method of Ti and Cu co-doped composite nitride film on fluororubber surface

Abstract

The invention discloses a preparation method of a Ti and Cu co-doped composite nitride film on the surface of fluororubber, which comprises the following steps: cleaning and blow-drying a fluororubber substrate, putting the fluororubber substrate into a magnetron sputtering cavity, pumping to a high vacuum condition, and introducing Ar gas to clean the substrate; and then the modified Ti and Cu co-doped composite nitride film is obtained by adopting a cathode arc magnetic filtration technology. The friction performance of the obtained Ti and Cu co-doped composite nitride thin film is obviously improved, meanwhile, the density of the thin film is kept, and the binding force of the Ti and Cu co-doped composite nitride thin film and a fluororubber substrate is improved; the cathode arc magnetic filtration technology enables the doped elements to be uniformly dispersed in the film, so that the performance of the film can be improved with a small amount of doped elements, and the tribological performance of the film is improved.

Description

Technical Field

[0001] The present invention belongs to the technical fields of vacuum coating and rubber sealing, and particularly relates to a method for preparing a Ti, Cu co-doped composite nitride film on the surface of fluororubber. Background Art

[0002] As a high-performance elastomer material, fluoroether rubber (FKM) has been widely used in the fields of aerospace, automotive manufacturing, petrochemical industry, etc. due to its excellent chemical stability, oil resistance, high temperature resistance, and outstanding sealing performance. Especially in the aerospace field, fluoroether rubber is used to manufacture key components such as engine seals and fuel system seals to cope with the environment of extreme temperature, high pressure, and corrosive media. In the automotive industry, fluoroether rubber is used to manufacture oil seals, O-rings and other components to meet the high requirements of the engine and transmission system for sealing materials. However, although fluoroether rubber performs well in static sealing applications, under dynamic conditions, especially when sliding relative to engineering materials such as ceramics and steel, its surface often exhibits a high friction coefficient and severe wear phenomenon. This not only reduces the service life of the material, but also affects the reliability and operating efficiency of the equipment, restricting the further application of fluoroether rubber in high-performance fields.

[0003] In order to improve the tribological properties of fluoroether rubber, current research mainly focuses on surface modification technologies. Among them, depositing hard films (such as metal nitride films or diamond-like carbon films) is a relatively common method. These films have high hardness, low friction coefficient, and excellent wear resistance, and can improve the surface properties of fluoroether rubber to a certain extent, reducing friction and wear. However, traditional film preparation technologies face many challenges when applied to the surface of fluoroether rubber. First, due to the chemical inertness of the fluoroether rubber surface, the interfacial bonding force between the film and the substrate is weak, resulting in insufficient film adhesion and easy peeling or failure. Second, as a flexible material, the surface of fluoroether rubber is prone to deformation during film deposition, making it difficult to achieve high-quality and uniform film deposition. In addition, traditional film preparation processes are usually complex and costly, which further limits their application in industrial production.

[0004] In recent years, researchers have tried a variety of improvement methods to address the above problems. For example, surface pretreatment techniques (such as plasma treatment, chemical treatment, etc.) are used to enhance the activity of the fluoroether rubber surface, thereby improving the bonding force between the film and the substrate. In addition, the use of new deposition techniques (such as magnetron sputtering, ion beam assisted deposition, etc.) has also been shown to improve the uniformity and adhesion of the film to a certain extent. However, these methods still have certain limitations in practical applications, such as complex processes, high costs, and difficulty in large-scale production. Therefore, how to prepare a film with high adhesion, good uniformity and excellent tribological properties on the surface of fluoroether rubber is still a key technical problem that needs to be solved in this field.

[0005] In summary, as an important sealing material, the improvement of the tribological properties of fluoroether rubber is of great significance for its application in high-end fields. Although current research has made some progress, it is still necessary to further explore new surface modification technologies and film preparation methods to achieve a comprehensive improvement in the surface properties of fluoroether rubber and promote its widespread application in high-performance fields. Summary of the invention

[0006] The invention discloses a method for preparing a Ti and Cu co-doped composite nitride film on the surface of fluororubber. A cathode arc magnetic filtering technology is adopted to obtain a modified Ti and Cu co-doped composite nitride film. The method can effectively improve the bonding force of the film, ensure the uniformity and stability of the film, thereby significantly improving the wear resistance of the fluororubber and reducing its friction coefficient.

[0007] 1. Preparation of Ti and Cu co-doped composite nitride films 1) First, the fluororubber substrate was ultrasonically cleaned with alcohol for 20 minutes to remove surface contaminants, and then placed on the sample holder in the vacuum chamber after drying; the vacuum was evacuated to a pressure of less than 5×10 -3 After the vacuum chamber reaches 0.4-0.5 Pa, high-purity argon gas is introduced, the pressure in the vacuum chamber is controlled to be 0.4-0.5 Pa, the bias power supply is adjusted to -600-800 V, and the surface of the substrate is bias cleaned to remove impurities on the surface of the substrate. The treatment time is 10-15 minutes; 2) First turn on the Ti target, adjust the Ti arc target current to 80~100A, the voltage to 22~25V, the argon flow rate to 200sccm, maintain the gas pressure at 0.50~0.55pa, the bias voltage to 700±30V, the duty cycle to 60~65%, the current to 0.2~0.25A, and the injection time to 25~30min; 3) Depositing a Ti metal layer: Open the baffle, adjust the Ti arc target current to 150 - 170 A, voltage to 30 - 33 V, the flow rate of argon introduced is 80 - 120 sccm, the air pressure is 0.25 - 0.30 pa, the deposition bias voltage is controlled at 70 - 75 V, the duty cycle is 60 - 70%, the current is controlled at 4.5 - 5.0 A, and the deposition time is 30 - 40 min; 4) Depositing a TiN layer: On the basis of step 3), the flow rate of nitrogen introduced is 100 - 120 sccm, the flow rate of argon remains unchanged, the voltage is 30 - 32 V, the air pressure is maintained at 0.30 - 0.35 pa, the deposition bias voltage is controlled at 75 - 80 V, the duty cycle is 60 - 70%, the current is controlled at 4.0 - 4.5 A, and continue the deposition for 60 min; 5) Depositing a CuTiN layer: On the basis of step 4), control the nitrogen flow rate unchanged (100 - 120 sccm) and the argon flow rate unchanged (100 - 120 sccm), the air pressure is maintained at 0.40 - 0.45 pa, the deposition bias voltage is controlled at 75 - 80 V, the duty cycle is 60 - 70%, the current is controlled at 4.0 - 4.5 A; Turn on the Cu target of the central column target, control the current to 1.0 - 1.2 A, the voltage to 310 - 320 V, the duty cycle to 60 - 65%, and the deposition time to 60 - 70 min.

[0008] During the above preparation process, the Ti arc target is arranged on one side of the vacuum chamber and connected to the vacuum chamber through a magnetic filtration elbow, and the magnetic field current on the side of the magnetic filtration elbow close to the Ti arc target is 75 - 85 A, and the magnetic field current on the side close to the vacuum chamber is 45 - 55 A; The Cu target of the central column target is located at the center of the vacuum chamber.

[0009] II. Performance evaluation and structure of the Ti, Cu co - doped composite nitride film 1. Performance evaluation Use a ball - on - disk tribometer to measure the friction and wear performance of the fluororubber coated with the Ti, Cu co - doped composite nitride film and the uncoated rubber in a dry air environment. The selected friction load is 3 N, the rotation speed is 500 r / min, the friction counter - part is a Φ6 mm 440c stainless steel ball, and the rotation radius is 4 mm; The friction coefficient curve is as follows Figure 2 as shown.

[0010] Through Figure 2 it can be known that the friction coefficient of the obtained Ti, Cu co - doped composite nitride film is stable between 0.30 and 0.32. Compared with the friction coefficient of the fluororubber without the film, which fluctuates around 1.35, the lubrication performance and wear resistance of the Ti, Cu co - doped composite nitride film are significantly improved.

[0011] 2. Structure of the Ti, Cu co - doped composite nitride film Figure 3 This is the surface morphology diagram of the Ti, Cu co-doped composite nitride film prepared by the cathode arc magnetic filtering technology of the present invention. It can be intuitively seen that the surface morphology of the co-doped film is relatively uniform on the substrate surface, and the particle size and distribution in the film layer are relatively consistent, which means that the film layer has a moderate thickness and good compactness, and the adhesion between the film layer and the substrate is good.

[0012] Figure 4 This is the X-cut trace of the Ti, Cu co-doped composite nitride film prepared by the cathode arc magnetic filtering technology of the present invention. It can be intuitively seen that obvious "X"-shaped cracks occurred during the cutting process, brittle fracture occurred, and this fracture extended to both sides of the incision, and no obvious serrated cracks were observed, which indicates that the film has good adhesion.

[0013] Compared with the prior art, the present invention has the following beneficial effects: Through the cathode arc magnetic filtering technology, the present invention has achieved several important breakthroughs in film preparation. First, this technology can effectively remove particulate impurities in metal ions, significantly improve the purity of the film, reduce internal defects, and lay a foundation for the excellent performance of the film. Second, by precisely controlling the distribution of doping elements, the present invention realizes the uniform dispersion of doping elements inside the film, so that a small amount of doping can significantly improve the mechanical properties and tribological properties of the film, avoiding the performance fluctuation problem caused by uneven doping in the traditional method.

[0014] In terms of interface bonding, the present invention innovatively adopts the combination of hard and soft metals (such as Ti, Cu), significantly enhancing the interface bonding force between the film and the fluororubber substrate. This design not only solves the problem that traditional nitride films are easily peeled off on flexible substrates, but also endows the film with better toughness and fatigue resistance, making it show stronger adaptability under dynamic working conditions.

[0015] In terms of tribological properties, the film prepared by the present invention forms a highly ordered interface structure during friction, showing a low friction coefficient and a low wear rate. In addition, the cathode arc magnetic filtering technology adopted by the present invention has a simple process and controllable cost, and is suitable for large-scale industrial production. By optimizing the proportion and distribution of doping elements, the present invention effectively controls the production cost while ensuring performance improvement, providing a feasible technical path for industrial application.

[0016] In summary, the Ti, Cu co-doped composite nitride film prepared by the cathode arc magnetic filtration technology of the present invention has achieved remarkable improvements in terms of film purity, interfacial bonding strength, tribological properties, etc. This method not only solves the peeling problem of traditional nitride films on flexible substrates, but also provides reliable technical support for the application of fluororubber in high-performance fields, and has important industrial application value and promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. is a schematic structural diagram of the Ti, Cu co-doped composite nitride film prepared by the present invention.

[0018] Figure 2 FIG. is a friction coefficient curve of the Ti, Cu co-doped composite nitride film prepared by the present invention.

[0019] Figure 3 FIG. is a scanning electron microscope image of the Ti, Cu co-doped composite nitride film with a thickness of 100 μm prepared by the present invention.

[0020] Figure 4 FIG. is a X-cut method cutting trace diagram of the Ti, Cu co-doped composite nitride film prepared by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The present invention will be further explained and described below with reference to specific embodiments. Embodiment

[0022] Refer to Figure 1 the structure shown, the preparation of the Ti, Cu co-doped composite nitride film of the present invention is as follows: 1) First, ultrasonically clean the fluororubber with alcohol for 20 min to remove surface contaminants, dry it and place it on the sample rack in the vacuum chamber; evacuate to a pressure less than 5×10 -3 Pa, then introduce high-purity argon gas, control the pressure in the vacuum chamber to 0.4~0.5 Pa, adjust the bias power supply to -600~-800 V, and perform bias cleaning on the substrate surface to remove surface impurities of the substrate, with a treatment duration of 10~15 min; 2) First, turn on the Ti target, adjust the Ti arc target current to 80~100 A, voltage to 20~25 V, the argon gas flow rate to 200 sccm, maintain the gas pressure at 0.50~0.55 Pa, the bias voltage is controlled at 700±30 V, the duty cycle is 60~65%, the current is controlled at 0.2~0.25 A, and the injection time is 25~30 min; 3) Depositing a Ti metal layer: Open the baffle, adjust the Ti arc target current to 150 - 170 A, voltage to 30 - 33 V, the flow rate of argon introduced is 80 - 120 sccm, the air pressure is 0.25 - 0.30 pa, the deposition bias voltage is controlled at 70 - 75 V, the duty cycle is 60 - 70%, the current is controlled at 4.5 - 5.0 A, and the deposition time is 30 - 40 min; 4) Depositing a TiN layer: On the basis of step 3), the flow rate of nitrogen introduced is 100 - 120 sccm, the flow rate of argon remains unchanged, the voltage is 30 - 32 V, the air pressure is maintained at 0.30 - 0.35 pa, the deposition bias voltage is controlled at 75 - 80 V, the duty cycle is 60 - 70%, the current is controlled at 4.0 - 4.5 A, and continue the deposition for 60 min; 5) Depositing a CuTiN layer: On the basis of step 4), keep the flow rate of nitrogen unchanged (100 - 120 sccm) and the flow rate of argon unchanged (100 - 120 sccm), the air pressure is maintained at 0.40 - 0.45 pa, the deposition bias voltage is controlled at 75 - 80 V, the duty cycle is 60 - 70%, the current is controlled at 4.0 - 4.5 A. Turn on the central column target Cu target, control the current at 1.0 - 1.2 A, the voltage at 310 - 320 V, the duty cycle at 60 - 65%, and the deposition time at 60 - 70 min.

[0023] For the structural characterization and performance evaluation, see above.

Claims

1. A method for preparing a Ti and Cu co-doped composite nitride film on a fluororubber surface, characterized in that: The composite nitride film includes a Ti metal bearing layer, a TiN intermediate transition layer and a CuTiN surface friction reducing layer deposited on the surface of fluororubber, and the specific steps are as follows: 1) First, the fluororubber substrate was ultrasonically cleaned with alcohol for 20 minutes to remove surface contaminants, and then placed on the sample holder in the vacuum chamber after drying; the vacuum was evacuated to a pressure of less than 5×10 -3 After the vacuum chamber reaches 0.4-0.5 Pa, high-purity argon gas is introduced, the pressure in the vacuum chamber is controlled to be 0.4-0.5 Pa, the bias power supply is adjusted to -600-800 V, and the surface of the substrate is bias cleaned to remove impurities on the surface of the substrate. The treatment time is 10-15 minutes; Ti and Cu co-doped composite nitride films were deposited using cathode arc magnetic filtration technology: 2) First turn on the Ti target, adjust the Ti arc target current to 80~100A, the voltage to 22~25V, the argon flow rate to 200sccm, maintain the gas pressure at 0.50~0.55pa, the bias voltage to 700±30V, the duty cycle to 60~65%, the current to 0.2~0.25A, and the injection time to 25~30min; 3) Deposition of Ti metal layer: open the baffle, adjust the Ti arc target current to 150~170A, the voltage to 30~33V, the flow rate of argon gas to 80~120sccm, the gas pressure to 0.25~0.30pa, the deposition bias to 70~75V, the duty cycle to 60~70%, the current to 4.5~5.0A, and the deposition time to 30~40min; 4) Deposition of TiN layer: Based on step 3), the nitrogen flow rate is 100~120sccm, the argon flow rate remains unchanged, the voltage is 30~32V, the gas pressure is maintained at 0.30~0.35pa, the deposition bias is controlled at 75~80V, the duty cycle is 60~70%, the current is controlled at 4.0~4.5A, and the deposition time is continued for 60min; 5) Deposition of CuTiN layer: Based on step 4), the flow rate of nitrogen and argon is controlled unchanged, the gas pressure is maintained at 0.40~0.45pa, the deposition bias is controlled at 75~80V, the duty cycle is 60~70%, and the current is controlled at 4.0~4.5A; turn on the central column target Cu target, control the current to 1.0~1.2A, the voltage to 310~320V, the duty cycle to 60~65%, and the deposition time to 60~70min.

2. The method for preparing a Ti and Cu co-doped composite nitride film on the surface of fluororubber as claimed in claim 1, characterized in that: During the above preparation process, the central column target Cu target is located in the center of the vacuum chamber, the Ti arc target is connected to the vacuum chamber through a magnetic filtration elbow, and the magnetic field current on the magnetic filtration elbow close to the Ti arc target is 75~85A, and the magnetic field current on the side close to the vacuum chamber is 45~55A.

Images