Preparation method of Cr and Cu co-doped composite nitride film on fluoroether rubber surface

Abstract

The invention discloses a preparation method of a Cr and Cu co-doped composite nitride film on the surface of fluoroether rubber, which comprises the following steps: cleaning and blow-drying a fluoroether rubber base material, putting the fluoroether rubber base material into a magnetron sputtering cavity, pumping to a high vacuum condition, and introducing argon to clean the substrate; and obtaining the modified Cr and Cu co-doped composite nitride film by adopting a cathode arc magnetic filtration technology. The friction performance of the obtained Cr and Cu co-doped composite nitride thin film is obviously improved, meanwhile, the density of the thin film is kept, and the binding force between the Cr and Cu co-doped composite nitride thin film and a fluoroether rubber 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 Cr, Cu co-doped composite nitride film on the surface of fluororubber. Background Art

[0002] Fluororubber (FKM) is widely used as a sealing material in the fields of aerospace, automotive, chemical engineering, etc. due to its good chemical stability, oil resistance and sealing performance. However, in actual use, when its surface slides relative to engineering materials such as ceramics and steel, high friction coefficients and severe wear will occur, affecting service life and reliability, and restricting its application in high-performance fields. To improve its tribological properties, current research mostly adopts surface modification technologies, such as depositing hard films (metal nitride films or diamond-like carbon films). These films have wear-resistant and low-friction characteristics and can improve the surface properties of fluororubber to a certain extent. However, traditional film preparation technologies have deficiencies when applied to the surface of fluororubber: weak film adhesion, uneven deposition, and complex processes. Due to the chemical inertness of the fluororubber surface, the interfacial bonding force between the film and the substrate is low, and it is easy to peel off or fail. In addition, it is difficult to achieve high-quality and uniform film deposition on the surface of flexible substrates, and the complexity and high cost of the preparation process limit its industrial application. Therefore, how to prepare a film with high adhesion, good uniformity and excellent tribological properties on the surface of fluororubber has become an urgent technical problem in this field. Summary of the Invention

[0003] In view of this, the present invention discloses a method for preparing a Cr, Cu co-doped composite nitride film on the surface of fluororubber. The modified Cr, Cu co-doped composite nitride film is obtained by using a cathodic arc magnetic filtering technology. This method can effectively improve the bonding force of the film, ensure the uniformity and stability of the film, and thus significantly improve the wear resistance of fluororubber and reduce its friction coefficient.

[0004] I. Preparation of Cr, Cu co-doped composite nitride film 1) First, ultrasonically clean the fluororubber substrate with alcohol for 10 - 20 min to remove surface contaminants. After drying, 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 be 0.3 - 0.5 Pa, adjust the bias power supply to -500 - 800 V, and perform bias cleaning on the substrate surface to remove surface impurities of the substrate. The treatment duration is 12 - 15 min; 2) First, turn on the Cr target, adjust the Cr arc target current to 100 - 120 A, voltage to 20 - 25 V, introduce argon gas with a flow rate of 200 sccm, maintain the air pressure at 0.50 - 0.55 pa, control the bias voltage at 700 ± 30 V, duty cycle at 60 - 70%, current at 0.1 A, and injection time at 30 min; 3) Deposit the Cr metal layer: Open the baffle, adjust the Cr arc target current to 150 - 170 A, voltage to 30 - 35 V, introduce argon gas with a flow rate of 80 - 120 sccm, air pressure at 0.30 - 0.32 pa, control the deposition bias voltage at 70 - 80 V, duty cycle at 60 - 70%, current at 4.0 - 4.5 A, and deposition time at 20 - 40 min; 4) Deposit the CrN layer: On the basis of step 3), introduce nitrogen gas with a flow rate of 100 - 120 sccm, keep the argon gas flow rate unchanged, maintain the air pressure at 0.30 - 0.35 pa, control the deposition bias voltage at 75 - 80 V, duty cycle at 60 - 70%, current at 4.0 - 4.5 A, and continue deposition for 60 min; 5) Deposit the CuCrN layer: On the basis of step 4), keep the nitrogen gas flow rate unchanged (100 - 120 sccm), maintain the air pressure at 0.40 - 0.45 pa. Turn on the central column target Cu target, control the current at 0.8 - 1.2 A, voltage at 300 - 320 V, duty cycle at 55 - 65%, and deposition time at 50 - 70 min.

[0005] During the above preparation process, the Cr arc target is set on one side of the vacuum chamber and connected to the vacuum chamber through a magnetic filtration elbow. The magnetic field current on the side of the magnetic filtration elbow close to the Cr arc target is 75 - 85 A, and the magnetic field current on the side close to the vacuum chamber is 45 - 55 A; the central column target Cu target is located at the center of the vacuum chamber.

[0006] II. Performance evaluation and structure of Cr and Cu co - doped composite nitride thin films 1. Performance evaluation Use a ball - on - disk tribometer to measure the friction and wear performance of rubber coated with Cr and Cu co - doped composite nitride thin films and uncoated rubber in a dry atmosphere. The selected friction load is 3 N, rotation speed is 1000 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.

[0007] It can be seen through Figure 2 that the friction coefficient of the Cr and Cu co - doped composite nitride thin film is stable between 0.32 and 0.35. Compared with the friction coefficient of the fluorine - ether rubber without the thin film, which fluctuates around 1.35, the lubrication performance and wear resistance of the Cr and Cu co - doped composite nitride thin film are significantly improved.

[0008] The microhardness and elastic modulus of the thin film were measured by a nanoindentation instrument using the continuous indentation method. The maximum indentation depth was set to 150 nm (ensuring that the indentation depth of the indenter during the test was less than 1 / 10 of the thin film thickness to avoid the influence of the substrate on the hardness test); at the same time, to reduce measurement errors, 5 points were selected for measurement for each sample during the test, and their average value was used as the final result of the experiment, as Figure 3 shown. The measured hardness of the Cr, Cu co-doped composite nitride thin film was 31.7 GPa, and the elastic modulus was 351.7 GPa. It exhibited excellent mechanical properties and had extremely high wear resistance and anti-deformation ability.

[0009] 2. Structure of the Cr, Cu co-doped composite nitride thin film Figure 4 This is the surface morphology diagram of the Cr, Cu co-doped composite nitride thin film prepared by the cathode arc magnetic filtering technology of the present invention. It can be intuitively seen the surface morphology of the co-doped thin film. The thin film is relatively uniformly distributed 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.

[0010] Compared with the prior art, the present invention has the following beneficial effects: Through the cathode arc magnetic filtering technology, the present invention can effectively remove the attached microparticles in metal ions, improve the purity of the deposited thin film; make the doping elements uniformly dispersed in the thin film, so as to ensure that a small amount of doping elements can improve the thin film performance; the order degree of the friction interface during the friction process of the thin film is significantly improved, with a low friction coefficient and low wear rate, and the tribological performance of the thin film is improved. This special Cr, Cu co-doped composite nitride thin film can significantly improve the deposition quality of the nitride thin film, with a simple method and controllable cost, and has guiding significance for industrial production. Description of the drawings

[0011] Figure 1 This is the structural schematic diagram of the Cr, Cu co-doped composite nitride thin film prepared by the present invention.

[0012] Figure 2 This is the friction coefficient curve of the Cr, Cu co-doped composite nitride thin film prepared by the present invention.

[0013] Figure 3 This is the hardness and elastic modulus curve of the Cr, Cu co-doped composite nitride thin film prepared by the present invention.

[0014] Figure 4 This is the scanning electron microscope image of the 400 μm Cr, Cu co-doped composite nitride thin film prepared by the present invention. Detailed implementation manners

[0015] The present invention will be further explained and illustrated below in conjunction with specific embodiments. Embodiment

[0016] Referring to Figure 1 the structure shown, the preparation of the Cr, Cu co-doped composite nitride film of the present invention is as follows: 1) First, ultrasonically clean the fluororubber substrate with alcohol for 10 - 20 min to remove surface contaminants. After drying, 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 be 0.3 - 0.5 Pa, adjust the bias power supply to -500 - 800 V, and perform bias cleaning on the substrate surface to remove surface impurities of the substrate. The treatment duration is 12 - 15 min; 2) First, turn on the Cr target, adjust the Cr arc target current to 100 - 120 A, voltage to 20 - 25 V, introduce argon gas at a flow rate of 200 sccm, maintain the pressure at 0.50 - 0.55 pa, control the bias voltage at 700 ± 30 V, duty cycle at 60 - 70%, current at 0.1 A, and injection time at 30 min; 3) Deposit the Cr metal layer: Adjust the Cr arc target current to 150 - 170 A, voltage to 30 - 35 V, introduce argon gas at a flow rate of 80 - 120 sccm, pressure at 0.30 - 0.32 pa, deposit bias voltage controlled at 70 - 80 V, duty cycle at 60 - 70%, current at 4.0 - 4.5 A, and deposition time at 20 - 40 min; 4) Deposit the CrN layer: On the basis of step 3), introduce nitrogen gas at a flow rate of 100 - 120 sccm, keep the argon gas flow rate unchanged, maintain the pressure at 0.30 - 0.35 pa, deposit bias voltage controlled at 75 - 80 V, duty cycle at 60 - 70%, current at 4.0 - 4.5 A, and continue deposition for 60 min; 5) Deposit the CuCrN layer: On the basis of step 4), keep the nitrogen gas flow rate unchanged (100 - 120 sccm), maintain the pressure at 0.40 - 0.45 pa; turn on the central column target Cu target, control the current at 0.8 - 1.2 A, voltage at 300 - 320 V, duty cycle at 55 - 65%, and deposition time at 50 - 70 min.

[0017] For the structure characterization and performance evaluation, refer to the above text.

Claims

1. A method for preparing a Cr and Cu co-doped composite nitride film on the surface of fluoroether rubber, characterized in that: The composite nitride film includes a Cr metal bearing layer, a CrN intermediate transition layer and a CuCrN surface friction reducing layer deposited on the surface of fluoroether rubber. The specific preparation steps are as follows: 1) First, ultrasonically clean the fluoroether rubber substrate with alcohol for 15-20 minutes to remove surface contaminants, blow dry it and place it on the sample holder in the vacuum chamber; evacuate the vacuum chamber to a pressure of less than 5×10 -3 After the vacuum chamber reaches 0.3-0.5 Pa, high-purity argon gas is introduced, the pressure in the vacuum chamber is controlled to be 0.3-0.5 Pa, the bias power supply is adjusted to -500-800 V, and the surface of the substrate is bias cleaned to remove impurities on the surface of the substrate. The treatment time is 12-15 minutes; Cr, Cu co-doped composite nitride films were deposited using cathode arc magnetic filtration technology: 2) First turn on the Cr target, adjust the Cr arc target current to 100~120A, the voltage to 20~25V, 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 60~70%, the current to 0.1A, and the injection time to 30min; 3) Deposition of Cr metal layer: adjust the Cr arc target current to 150~170A, voltage to 30~35V, flow rate of argon gas to 80~120sccm, gas pressure to 0.30~0.32pa, deposition bias to 70~80V, duty cycle to 60~70%, current to 4.0~4.5A, deposition time to 20~40min; 4) Deposition of CrN layer: Based on step 3), the nitrogen flow rate is 100-120sccm, the argon flow rate remains unchanged, 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 CuCrN layer: Based on step 4), the nitrogen flow rate is controlled unchanged and the gas pressure is maintained at 0.40~0.45pa; the central column target Cu target is turned on, the current is controlled to be 0.8~1.2A, the voltage is 300~320V, the duty cycle is 55~65%, and the deposition time is 50~70min.

2. The method for preparing a Cr and Cu co-doped composite nitride film on the surface of fluoroether rubber 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 Cr 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 magnetic filtration elbow close to the Cr arc target is 75~85A, and the magnetic field current on the side close to the vacuum chamber is 45~55A.

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