A corrosion-resistant, wear-resistant, low-friction carbon composite film and its preparation and application on the surface of rolling bearings

Abstract

The present invention discloses a corrosion-resistant, wear-resistant, low-friction carbon composite film, which is applied to the surface of rolling bearings in marine environments and has the characteristics of excellent corrosion resistance, low friction coefficient, long wear-resistant life, etc., and belongs to the field of vacuum coating technology and the field of bearing surface treatment technology. The present invention adopts a closed magnetic field-multi-target sputtering deposition technology, with Ti and graphite as sputtering targets, argon as sputtering gas, and methane as reaction gas, and is prepared by a reaction + sputtering co-deposition method. Its structure is Ti bonding layer, TiN bearing layer, TiNC gradient layer, TiC / C functional layer from the inside to the outside of the workpiece surface. This multi-layer gradient structure effectively improves the film's load-bearing capacity and wear resistance; at the same time, the dispersion strengthening effect of nanocrystalline TiC / amorphous carbon in the functional layer improves the film's corrosion resistance and low friction performance, and is applied to the surface of rolling bearings to improve the long life and high-reliability lubrication service performance of the bearing in a corrosive environment.

Description

Technical Field

[0001] The present invention relates to a corrosion-resistant, wear-resistant, low-friction carbon composite film and a preparation method thereof, which is applied to the surface of rolling bearings in marine environments and has the characteristics of excellent corrosion resistance, low friction coefficient, long wear life, etc., and belongs to the technical field of vacuum coating and the technical field of bearing surface treatment. Background Art

[0002] With the implementation of my country's strategy of building a strong maritime nation and the expansion of the use of marine resources, more and more marine equipment, such as ships, carrier-based aircraft, and marine engineering equipment, need to serve for a long life and high reliability in a marine corrosive environment. Among them, bearings, as key basic components of marine equipment, directly determine the performance, quality, and reliability of marine equipment. When bearings serve in a marine environment, they will inevitably be coupled with chemical corrosion and mechanical wear, resulting in more severe corrosion and wear damage to the bearings than in an inland environment, seriously affecting the reliability and service life of related equipment. According to statistics, bearing failures due to corrosion, friction, and wear in a marine environment account for more than 60% of the total bearing failures.

[0003] In order to improve the corrosion resistance, wear resistance and self-lubricating performance of bearings, bearing companies such as Germany's Schaeffler, Sweden's SKF, the United States' Timken, and Japan's NSK have developed reliable bearing surface treatment technologies and surface film materials, including chemical plating of ZnNi, ZnFe, NiP, ZnP, Cr and other corrosion-resistant films, vacuum ion plating of TiN, CrN, CrCN wear-resistant films, magnetron sputtering MoS2-based films, plasma chemical vapor deposition (PECVD) diamond-like carbon-based films, and spraying of polytetrafluoroethylene and other lubricating films. In recent years, China has also begun to pay attention to the application of film materials on bearing surfaces.

[0004] When bearings are in service in marine environments, they are subject to the interactive damage of corrosion and wear. At the same time, dry friction conditions exist when the oil is poor and lacks oil. Therefore, there is a clear demand for film materials that have excellent corrosion resistance, high wear resistance and low friction coefficient (dry friction self-lubricating performance). However, the films currently developed only consider the performance requirements of one aspect. For example, ZnNi and others only have good corrosion resistance but do not have wear resistance and self-lubricating performance. TiN and others have high hardness and good wear resistance but poor self-lubricating and corrosion resistance. MoS2 films have excellent self-lubricating performance in vacuum but their performance drops sharply in corrosive environments. Polytetrafluoroethylene has good self-lubricating and corrosion resistance but has low hardness and poor wear resistance. The high-hardness diamond-like carbon-based film prepared by PECVD has good mechanical and chemical inertness properties. It has attracted attention as a wear-resistant protective film and has been applied in the field of high-end bearings. However, the high-hardness carbon-based film still has the following problems: ① It has very high internal stress, resulting in poor bonding between the film and the substrate. ② Low toughness and high brittleness, prone to brittle peeling under strong impact. ③ Large friction coefficient under dry friction (>0.2). Therefore, how to achieve the integrated design of high corrosion resistance, high wear resistance and low friction functions of carbon-based composite films through carbon film structure regulation has not been properly solved. Summary of the invention

[0005] The purpose of the present invention is to provide a corrosion-resistant, wear-resistant and low-friction carbon composite film and a preparation method thereof, which is mainly used for the corrosion resistance, wear resistance and self-lubrication of the rolling bearing surface in the marine environment.

[0006] 1. Structure and preparation of corrosion-resistant, wear-resistant and low-friction carbon composite films

[0007] The corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention has a structure that is Ti bonding layer, TiN bearing layer, TiNC gradient layer and TiC / C functional layer from the inside to the outside of the workpiece surface. Figure 1 As shown. Among them, the role of the Ti bonding layer is to improve the bonding strength of the film substrate, and its T thickness is 300~500 nm. The role of the TiN bearing layer is to improve the high load bearing capacity of the overall composite film layer and improve the wear resistance, and its thickness is 1200~2000 nm. The role of the TiNC gradient layer is to reduce the stress caused by lattice mismatch between the TiN layer and the TiC / C functional layer. The role of the TiC / C functional layer is to provide excellent corrosion resistance and lubrication performance, and its thickness is 1200~2000nm.

[0008] The method for preparing the corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention comprises the following steps:

[0009] (1) Surface activation of workpieces: The cleaned workpiece to be plated is fixed on the sample holder in the closed magnetic field-reactive magnetron sputtering vacuum deposition chamber and rotated at a speed of 3 to 5 rpm; the vacuum deposition chamber is evacuated to a pressure of no more than 4.0×10 -3 Pa, high-purity argon gas is introduced, the deposition gas pressure is controlled to be 0.5~1.0 Pa, and a negative bias voltage of 400~600V is applied to the substrate of the plated workpiece for plasma cleaning for 20~40 min.

[0010] The materials of the plated workpieces are high carbon chromium bearing steel (GCr15, GCr18SiMo), carburized bearing steel (G20CrMo, G20CrNiMo), austenitic stainless steel (1Cr18Ni9Ti), martensitic stainless steel (9Cr18, 9Cr18Mo), high speed steel (8Cr4Mo4V), high nitrogen steel (40Cr15Mo2VN). The cleaning of the plated workpiece is to ultrasonically clean the plated workpiece in petroleum ether and acetone for 20 to 30 minutes.

[0011] (2) Preparation of Ti bonding layer: adjust the argon flow rate to 30-50 sccm, control the deposition gas pressure to 0.1-0.3 Pa, turn on the Ti target sputtering power supply, control the sputtering current to 3-5 A, adjust the substrate negative bias voltage to 100-200 V, and deposit the Ti bonding layer.

[0012] (3) Preparation of TiN carrier layer: Keep the above conditions unchanged, introduce N2 at a flow rate of 5-10 sccm, and deposit the TiN carrier layer.

[0013] (4) Preparation of TiNC gradient layer: Keep the above conditions unchanged, turn on the graphite target power supply, control the sputtering current to 4-6A, and deposit the TiNC gradient layer.

[0014] (5) Preparation of TiC / C functional layer: turn off N2 and introduce CH4 gas, adjust the volume ratio of CH4 gas to argon gas to 4:2~4:3, adjust the Ti target sputtering current to 1~2 A, the graphite target sputtering current to 4~6 A, and the substrate negative bias voltage to 100~300 V; deposit the TiC / C functional layer.

[0015] Experiments show that as the ratio of CH4 to argon increases, the Ti target sputtering current, graphite target sputtering current and substrate negative bias voltage increase accordingly, which ensures that there is enough hydrocarbon source to decompose into hydrocarbon active ions, while ensuring that the Ti target and graphite target are in a slightly poisoned condition, ensuring that there are sufficient hydrocarbon active ions and sufficient ion energy to grow into nanocrystalline TiC / amorphous carbon composite films.

[0016] Figure 2 This is a high-resolution transmission electron morphology image of the TiC / C functional layer of the corrosion-resistant, wear-resistant and low-friction carbon composite film. Figure 2It can be seen that the TiC / C functional layer is a nanocomposite structure in which TiC nanocrystals are embedded in an amorphous carbon film, in which the TiC nanocrystals play a role of dispersion strengthening, making the TiC / C functional layer have excellent anti-friction and wear properties and corrosion resistance.

[0017] 2. Performance of corrosion-resistant, wear-resistant and low-friction carbon composite films

[0018] The tribological properties of the corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention were tested under dry friction and grease lubrication. A ball-disc friction tester was used, the friction pair was a GCr15 steel ball of Φ 8 mm, the contact pressure was 5N, the rotation speed was 1000 rpm, the dry friction was 6×10 5 Stop test after rotation, grease lubrication 1.5×10 6 The test is stopped after the switch. Figure 3 The film friction coefficient under dry friction is 0.06, and the film friction coefficient under dry friction is 0.06. 5 The wear depth after rotational friction is 1.62 μm, and the corresponding wear rate is 1.6×10 -7 mm 3 / Nm. The film friction coefficient under grease lubrication is 0.03, and the friction coefficient of 1.5×10 6 The wear depth after rotational friction is 0.84 μm, and the corresponding wear rate is 0.4×10 -7 mm 3 / Nm. The film has excellent low friction, self-lubrication, high wear resistance and long wear life characteristics.

[0019] Acidic salt spray tests were performed on high nitrogen steel (40Cr15Mo2VN) specimens and high nitrogen steel bearings treated with the corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention. A salt spray corrosion test chamber was used, and a sodium chloride aqueous solution was prepared with a concentration of 5%±1% in accordance with the provisions of GB / T 10125-2012. An appropriate amount of acetic acid was added to ensure that the pH value of the solution was 3.5±0.5, and the test temperature was 35±2°C. With reference to the provisions of GJB150 150.11A-2009, the specimens were placed in a salt spray test chamber and subjected to 24-hour salt spraying and 24-hour drying. This was one cycle. Four cycles were performed continuously for a total of 192 hours of testing (four spray wetting stages and four drying stages). The test was rated after the test in accordance with the provisions of GB / T 6461-2002. The test results are as follows: Figure 4 After the 192 acid salt spray test, the high nitrogen steel (40Cr15Mo2VN) sample plated with corrosion-resistant, wear-resistant and low-friction carbon composite film and the high nitrogen steel bearing surface were free of corrosion, and the corrosion resistance grade was 10.

[0020] A neutral salt spray test was conducted on the high nitrogen steel (40Cr15Mo2VN) sample and bearing treated with the corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention. A salt spray corrosion test chamber was used, and according to the provisions of GB / T 10125-2012, a sodium chloride aqueous solution was prepared with a concentration of 5%±1%, pH=6.8, and a test temperature of 35±2°C. According to the provisions of GJB150 150.11A-2009, the sample was placed in the salt spray test chamber for 1500 hours, and the appearance was observed. The results are as follows: Figure 5 After 1500 h of neutral salt spray test, the high nitrogen steel (40Cr15Mo2VN) specimens and high nitrogen steel bearing surfaces coated with corrosion-resistant, wear-resistant and low-friction carbon composite films showed no corrosion.

[0021] In summary, the present invention adopts a closed magnetic field-multi-target sputtering deposition technology, with Ti and graphite as sputtering targets, argon as sputtering gas, and methane as reaction gas, and prepares a multi-layer gradient carbon composite film by a reaction + sputtering co-deposition method, which effectively improves the film's load-bearing capacity and wear resistance; at the same time, the dispersion strengthening effect of the functional layer of nanocrystalline TiC / amorphous carbon improves the film's corrosion resistance and low friction performance, and its application to the surface of rolling bearings can improve the bearing's long life and high-reliability lubrication service performance in corrosive environments (such as marine environments). BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a cross-sectional view of the corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention.

[0023] Figure 2 This is a high-resolution transmission electron morphology image of the TiC / C functional layer of the corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention.

[0024] Figure 3 The friction coefficient curves and wear scar depths of the corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention under dry friction and grease lubrication respectively.

[0025] Figure 4 These are photos of high nitrogen steel (40Cr15Mo2VN) samples and high nitrogen steel bearings treated with the corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention after 192 hours of acidic salt spray test.

[0026] Figure 5 These are photos of high nitrogen steel (40Cr15Mo2VN) samples and high nitrogen steel bearings treated with the corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention after 1500 hours of neutral salt spray test. DETAILED DESCRIPTION

[0027] In order to better understand the present invention, the preparation and performance of the corrosion-resistant, wear-resistant and low-friction carbon composite film of the present invention are further described below through specific examples.

[0028] Example 1

[0029] (1) Select 40Cr15Mo2VN high nitrogen steel specimens and bearings, place them in petroleum ether and acetone for ultrasonic cleaning for 30 min respectively, then move them into a closed magnetic field-reactive magnetron sputtering vacuum deposition chamber and fix them on a sample holder to ensure that the bearings can revolve and rotate;

[0030] (2) Evacuate the vacuum deposition chamber to 2.0×10 -3 Pa; the test piece and the bearing rotate at a speed of 5 rpm; high-purity argon gas is introduced, the deposition pressure is controlled at 1.0 Pa, a negative bias of 600 V is applied to the test piece and the bearing substrate, and plasma cleaning is performed for 20 min;

[0031] (3) Adjust the argon gas flow rate to 50 sccm, control the deposition gas pressure to 0.3 Pa, turn on the Ti target sputtering power supply, control the sputtering current to 5 A, adjust the substrate negative bias voltage to 200 V, and deposit a 500 nm Ti bonding layer;

[0032] (4) Keeping the above conditions unchanged, N2 flow rate was 10 sccm, and a TiN carrier layer of 2000 nm was deposited;

[0033] (5) Keeping the above conditions unchanged, turn on the graphite target power supply to control the sputtering current to 6A and deposit a 400nm TiNC gradient layer;

[0034] (6) Turn off N2 and introduce CH4 gas, adjusting the ratio of CH4 to argon to 4:2. Regulate the sputtering current of Ti target to 2 A, the sputtering current of graphite target to 6 A, and the negative bias voltage of substrate to 300 V. Deposit 2000 nm TiC / C functional layer.

[0035] The properties of the obtained composite film are as follows: black, dense and smooth appearance, film thickness 4.9 μm, dry friction coefficient 0.05, dry wear life 9.6×10 5 There is no corrosion after 192h acid salt spray test and 1500h neutral salt spray test.

[0036] Example 2

[0037] (1) Select 9Cr18 stainless steel specimens and bearings, place them in petroleum ether and acetone for ultrasonic cleaning for 20 min respectively, then move them into a closed magnetic field-reactive magnetron sputtering vacuum deposition chamber and fix them on a sample holder to ensure that the bearings can revolve and rotate;

[0038] (2) Evacuate the vacuum deposition chamber to 1.0×10 -3Pa; the test piece and the bearing rotate at a speed of 3 rpm; high-purity argon gas is introduced, the deposition pressure is controlled to be 0.5 Pa, a negative bias of 400 V is applied to the test piece and the bearing substrate, and plasma cleaning is performed for 20 min;

[0039] (3) Adjust the argon gas flow rate to 30 sccm, control the deposition gas pressure to 0.1 Pa, turn on the Ti target sputtering power supply, control the sputtering current to 3 A, adjust the substrate negative bias voltage to 100 V, and deposit a 300 nm Ti bonding layer;

[0040] (4) Keeping the above conditions unchanged, N2 flow rate was 5 sccm, and a TiN carrier layer of 1200 nm was deposited;

[0041] (5) Keeping the above conditions unchanged, turn on the graphite target power supply, control the sputtering current to 4 A, and deposit a 200 nm TiNC gradient layer;

[0042] (6) Turn off N2, introduce CH4 gas and adjust the ratio of CH4 to argon to 4:3, adjust the Ti target sputtering current to 1 A, the graphite target sputtering current to 4 A, and the substrate negative bias voltage to 100 V. Deposit a 1200 nm TiC / C functional layer.

[0043] The properties of the obtained composite film are as follows: black, dense and smooth appearance, film thickness 2.9 μm, dry friction coefficient 0.07, dry wear life 6.5×10 5 There is no corrosion after 192h acid salt spray test and 1500h neutral salt spray test.

[0044] Example 3

[0045] (1) Select 1Cr18Ni9Ti stainless steel specimens and bearings, place them in petroleum ether and acetone for ultrasonic cleaning for 25 min respectively, then move them into a closed magnetic field-reactive magnetron sputtering vacuum deposition chamber and fix them on a sample holder to ensure that the bearings can revolve and rotate;

[0046] (2) Evacuate the vacuum deposition chamber to a pressure no greater than 3.0×10 -3 Pa; the test piece and the bearing body rotate at a speed of 4 rpm; high-purity argon gas is introduced, the deposition pressure is controlled to be 0.8 Pa, a negative bias of 500 V is applied to the test piece and the bearing substrate, and plasma cleaning is performed for 30 min;

[0047] (3) Adjust the argon gas flow rate to 40 sccm, control the deposition gas pressure to 0.2 Pa, turn on the Ti target sputtering power supply, control the sputtering current to 4 A, adjust the substrate negative bias voltage to 150 V, and deposit a 400 nm Ti bonding layer;

[0048] (4) Keeping the above conditions unchanged, N2 flow rate was 8 sccm, and a TiN carrier layer of 1500 nm was deposited;

[0049] (5) Keeping the above conditions unchanged, turn on the graphite target power supply to control the sputtering current to 5A and deposit a 300nm TiNC gradient layer;

[0050] (6) Turn off N2, introduce CH4 gas and adjust the ratio of CH4 to argon to 4:2.5, adjust the Ti target sputtering current to 1.5 A, the graphite target sputtering current to 5 A, the substrate negative bias voltage to 200 V, and deposit a 1500 nm TiC / C functional layer.

[0051] The properties of the obtained composite film are as follows: black, dense and smooth appearance, film thickness 3.7 μm, dry friction coefficient 0.06, dry wear life 8.4×10 5 There is no corrosion after 192h acid salt spray test and 1500h neutral salt spray test.

Claims

1. A method for preparing a corrosion-resistant, wear-resistant and low-friction carbon composite film, comprising the following steps: (1) Cleaning and placement of the plated bearings: The plated bearings are placed in petroleum ether and acetone for ultrasonic cleaning for 20 to 30 minutes respectively, and then moved to the closed magnetic field-reactive magnetron sputtering vacuum deposition chamber and fixed on the sample holder to ensure that the bearings can revolve and rotate; (2) Activation of the plated bearing surface: Evacuate the vacuum deposition chamber to a pressure not greater than 4.0×10 -3 Pa; the plated bearing rotates at a speed of 3-5 rpm; high-purity argon gas is introduced, the deposition pressure is controlled at 0.5-1.0 Pa, a negative bias voltage of 400-600 V is applied to the bearing substrate, and plasma cleaning is performed for 20-40 min; (3) Preparation of Ti bonding layer: adjust the argon flow rate to 30-50 sccm, control the deposition gas pressure to 0.1-0.3 Pa, turn on the Ti target sputtering power supply, control the sputtering current to 3-5 A, adjust the substrate negative bias voltage to 100-200 V, and deposit a Ti bonding layer of 300-500 nm to improve the film-substrate bonding strength; (4) Preparation of TiN carrier layer: Keep the conditions unchanged, introduce N2 at a flow rate of 5-10 sccm, and deposit a TiN carrier layer of 1200-2000 nm; (5) Preparation of TiNC gradient layer: Keep the conditions unchanged, turn on the graphite target power supply, control the sputtering current to 4-6A, and deposit a TiNC gradient layer of 300-500 nm; (6) Preparation of TiC / C functional layer: turn off N2 and introduce CH4 gas to adjust the ratio of CH4 to argon to 4:2~4:3, adjust the Ti target sputtering current to 1~2 A, the graphite target sputtering current to 4~6 A, the substrate negative bias voltage to 100~300 V, and deposit a TiC / C functional layer of 1200~2000 nm.

2. The method for preparing the corrosion-resistant, wear-resistant and low-friction carbon composite film according to claim 1, characterized in that: In step (1), the bearing material to be plated is high carbon chromium bearing steel GCr15, high carbon chromium bearing steel GCr18SiMo, carburized bearing steel G20CrMo, carburized bearing steel G20CrNiMo, austenitic stainless steel 1Cr18Ni9Ti, martensitic stainless steel 9Cr18, martensitic stainless steel 9Cr18Mo, high speed steel 8Cr4Mo4V, and high nitrogen steel 40Cr15Mo2VN.

3. Application of the corrosion-resistant, wear-resistant and low-friction carbon composite film as claimed in claim 1 or 2 on the surface of rolling bearings in marine environments.

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