A multi-sublayer cyclic graphitic carbon / molybdenum disulfide composite coating, a preparation method and application thereof

Abstract

The application discloses a kind of with multi-sublayer circulation amorphous carbon / molybdenum disulfide composite coating and its preparation method and application, belong to coating material technical field.The application adopts multi-target magnetron sputtering system to construct multi-sublayer circulation graphite-like carbon / molybdenum disulfide composite coating, sequentially including substrate surface treatment, chromium metal bonding layer and gradient transition layer (Cr→Cr / a-C→a-C) are deposited on substrate surface, high-hardness a-C support layer (a-C) is deposited on the surface of gradient transition layer (Cr→Cr / a-C→a-C), graphite-like carbon sublayer (GLC), sulfur-doped graphite-like carbon sublayer (S / GLC) and molybdenum disulfide sublayer (MoS2) are alternately deposited on the surface of a-C layer, and graphite-like carbon top layer is deposited on the surface of circulation multi-sublayer.The multi-sublayer circulation graphite-like carbon / molybdenum disulfide composite coating significantly improves the environmental sensitivity of traditional hydrogen-free amorphous carbon and molybdenum disulfide coating, and can realize excellent lubrication and wear resistance in vacuum, dry and humid atmosphere and other environments.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coating material preparation, and relates to a multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating suitable for multiple environments such as atmosphere and vacuum, and a preparation method and application thereof. BACKGROUND

[0002] Molybdenum disulfide is a typical "layered" solid lubricant material, and the weak van der Waals force between layers endows it with an ultra-low friction coefficient (lower than 0.01) in a vacuum environment, and it has been successfully applied in the field of aerospace lubrication. However, the lubricating performance of molybdenum disulfide significantly degrades in a humid atmosphere environment, mainly due to the oxidation induced by water and oxygen, and therefore it cannot be used in a humid atmosphere environment. Generally, before being launched into space, aerospace mechanical components need to go through ground atmospheric environment tests, debugging, transportation and other links, and the environmental sensitivity of traditional molybdenum disulfide coatings seriously limits their application in the field of aerospace.

[0003] Research shows that doping metal elements (Ti, Pb, Au, etc.) can improve the tribological performance of molybdenum disulfide coatings in atmospheric environments, but the friction coefficient of the doped coating is still relatively high in a humid atmosphere, and the hardness of the doped coating is usually lower than 6 GPa, and the mechanical properties and load capacity of the doped coating still need to be enhanced. Chinese patent (CN102994947A) proposes a diamond-like composite molybdenum disulfide nano-multilayer film, which has high hardness (>10 GPa) and can have an ultra-low friction coefficient in atmospheric and high vacuum environments. However, the tribological performance of hydrogen-free diamond-like carbon and pure molybdenum disulfide coatings in a humid atmosphere environment is poor, and therefore they may not be suitable for use in a humid atmosphere environment.

[0004] In summary, the sensitivity of molybdenum disulfide coatings to a humid atmosphere environment and the poor load capacity are the key bottlenecks that limit their application in high-end equipment fields. Therefore, it is of great significance to further improve the multi-environment adaptability and mechanical properties of molybdenum disulfide-based coatings by designing the coating structure and composition, so as to expand their application in high-end equipment fields. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating and a preparation method and application thereof, so as to solve the technical problems of the sensitivity of existing molybdenum disulfide coatings to a humid atmosphere environment and poor load capacity.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] The application discloses a multi-sublayer circulation graphite-like carbon / molybdenum disulfide composite coating, which is composed of a chromium metal adhesive layer, a gradient transition layer, a hard amorphous carbon support layer, a multi-sublayer circulation target layer and a graphite-like carbon top layer arranged above a substrate in sequence.

[0008] The gradient transition layer is composed of a chromium-doped amorphous carbon layer with linearly reduced chromium content, and the linearly reduced chromium content is used to form a composition gradient change from the chromium adhesive layer to the a-C layer, so that the adhesion is improved.

[0009] The hard amorphous carbon support layer is composed of hydrogen-free amorphous carbon or high-hardness amorphous carbon with a hydrogen content lower than 10%, and the nanohardness of the hydrogen-free amorphous carbon or the low-hydrogen amorphous carbon is not lower than 20 GPa; the hydrogen-free amorphous carbon or the low-hydrogen amorphous carbon has high hardness, and a too high hydrogen content can reduce the hardness of the amorphous carbon.

[0010] The multi-sublayer circulation target layer comprises a plurality of layers, each layer is sequentially deposited by a graphite-like carbon sublayer, a sulfur-doped graphite-like carbon sublayer and a molybdenum disulfide sublayer from bottom to top, and the modulation period of the multi-sublayer circulation target layer is 4.5 nm to 30 nm; the atomic percentage of S element in the sulfur-doped graphite-like carbon sublayer is 2% to 10%.

[0011] The modulation period of 4.5 nm to 30 nm means that the total thickness is less than 30 nm, so that the three-sublayer structure is a nanometer multi-layer structure, the organic integration of the characteristics of each sublayer can be better realized, and an excellent comprehensive performance is difficult to obtain when the period is too large. A too high S element content can cause the mechanical performance of S / a-C to degrade and the wear resistance to decrease.

[0012] Preferably, the total thickness of the composite coating is 1.0 µm to 6.0 µm.

[0013] The application further discloses a preparation method of the multi-sublayer circulation graphite-like carbon / molybdenum disulfide composite coating.

[0014] 1) performing argon ion (Ar + ) etching on the surface of the substrate after drying treatment;

[0015] 2) depositing a chromium metal adhesive layer on the surface of the substrate after Ar + etching;

[0016] 3) depositing a gradient transition layer of Cr→Cr / a-C→a-C on the surface of the chromium metal adhesive layer;

[0017] 4) depositing a hard amorphous carbon support layer on the surface of the gradient transition layer;

[0018] 5) sequentially depositing a graphite-like carbon sublayer, a sulfur-doped graphite-like carbon sublayer and a molybdenum disulfide sublayer on the surface of the hard amorphous carbon support layer to form a sublayer target layer;

[0019] 6) Repeat step 5) several times until a multi-sublayer cycle target layer is obtained;

[0020] 7) Depositing a graphite-like carbon top layer on the surface of the multi-sublayer cycle target layer to complete the coating preparation.

[0021] Preferably, in step 1), the substrate is sequentially subjected to grinding, polishing, ultrasonic cleaning and drying treatment before etching, and the grinding and polishing is performed to a roughness Ra of less than 0.1 μm.

[0022] Preferably, in step 1), the process parameters of argon ion etching are as follows: argon flow rate is 20-40 sccm, substrate bias voltage is -600 to -750 V, and time length is 1200-2400 s; and in step 2), the process parameters of depositing the chromium metal adhesion layer are as follows: target current is 2.0-4.0 A, and substrate bias voltage is -60 to -100 V.

[0023] Preferably, in step 3), a multi-target non-equilibrium magnetron sputtering system is used to deposit a gradient transition layer on the surface of the chromium metal adhesion layer, and the process parameters are as follows: chromium target current is linearly reduced from 2.0-4.0 A to 0 A, while graphite target current is linearly increased from 0 A to 1.5-4.0 A, target current change time is 600-1800 s, and argon flow rate is 10-20 sccm.

[0024] Preferably, in step 4), a multi-target non-equilibrium magnetron sputtering system is used to deposit a hard amorphous carbon support layer on the surface of the gradient transition layer, and the process parameters are as follows: graphite target current is 1.5-4.0 A, bias voltage is -100 to -200 V, argon flow rate is 10-25 sccm, and sample rotation speed is 5-10 rpm; and the thickness of the hard amorphous carbon support layer is 0.3-1.0 μm.

[0025] Preferably, in step 5), a multi-target non-equilibrium magnetron sputtering system is used to sequentially deposit a graphite-like carbon sublayer, a sulfur-doped graphite-like carbon sublayer and a molybdenum disulfide sublayer on the surface of the hard amorphous carbon support layer, and the process parameters are as follows: graphite target current is 1.5-4.0 A, sulfur-graphite mixed target current is 2.0-4.0 A, molybdenum disulfide target current is set to 0.5-1.5 A, bias voltage is -60 to -120 V, and sample rotation speed is 0.5-3 rpm; and the thickness of one sublayer is 1.5-10 nm.

[0026] Preferably, in step 7), a multi-target magnetron sputtering is used to deposit a graphite-like carbon top layer on the surface of the multi-sublayer cycle target layer, and the process parameters are as follows: graphite target current is 1.5-4.0 A, bias voltage is -60 to -100 V, sample rotation speed is 5-10 rpm, and the thickness is 0.1-0.5 μm.

[0027] The application further discloses application of the multi-sublayer cyclic graphite-like carbon / molybdenum disulfide composite coating in preparation of aerospace high-end equipment.

[0028] Compared with the prior art, the application has the following beneficial effects:

[0029] The multi-sublayer cyclic graphite-like carbon / molybdenum disulfide composite coating disclosed by the application combines molybdenum disulfide, graphite-like carbon and sulfur-doped graphite-like carbon three kinds of lubricating materials organically through a nano-composite multi-layer structure design, cooperates tribological properties of each sublayer, effectively improves poor vacuum tribological properties of hydrogen-free amorphous carbon coating, and significantly improves mechanical properties of molybdenum disulfide and tribological properties in humid atmosphere, so that excellent lubrication and wear resistance in various environments such as vacuum, dry / humid atmosphere are realized. The specific innovative advantages are as follows:

[0030] 1) The application designs a multi-sublayer composite structure to combine graphite-like carbon-based materials and molybdenum disulfide organically, so that the application not only has an ultra-low friction coefficient in a vacuum or high vacuum environment, but also has excellent lubrication properties in a dry and humid atmosphere environment, and the average friction coefficient is less than 0.05;

[0031] 2) The application designs a dense graphite-like top layer to prevent oxidation of the molybdenum disulfide layer by humid atmosphere, and the high-hardness amorphous carbon support layer and the graphite-like carbon layer can effectively improve the wear resistance of the molybdenum disulfide-based coating in an atmospheric environment. Compared with hydrogen-free amorphous carbon, the vacuum wear rate of the composite coating is improved by 1-2 orders of magnitude; compared with a pure molybdenum disulfide coating, the wear rate of the composite coating in a humid atmosphere environment is improved by 1 order of magnitude;

[0032] 3) The application introduces a high-hardness amorphous carbon layer and a graphite-like carbon sublayer with relatively high hardness, so that the mechanical properties of the molybdenum disulfide coating are significantly enhanced, the load-carrying capacity of the molybdenum disulfide-based coating is effectively improved, and the molybdenum disulfide-based coating can be applied to medium and high load lubrication working conditions.

[0033] The preparation method of the above-mentioned multi-sublayer circulation graphite-like carbon / molybdenum disulfide composite coating discloses a multi-target magnetron sputtering system, and sequentially comprises substrate surface treatment, deposition of a chromium metal adhesive layer and a gradient transition layer (Cr→Cr / a-C→a-C) on the substrate surface, deposition of a high-hardness a-C support layer (a-C) on the surface of the gradient transition layer (Cr→Cr / a-C→a-C), and deposition of a graphite-like carbon sublayer (GLC), a sulfur-doped graphite-like carbon sublayer (S / GLC) and a molybdenum disulfide sublayer (MoS2) on the surface of the a-C layer in sequence. The multi-sublayer circulation deposition is realized by precisely controlling the rotation speed of a single-axis clamp and the installation design of a multi-target position to realize the deposition of ordered nanometer multi-sublayers. The multi-sublayer is sequentially deposited once every time the sample rotates one round, and the preparation operation is simple. The graphite-like carbon / molybdenum disulfide composite coating has excellent tribological properties in various environments such as vacuum, dry and humid atmosphere. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 A structure schematic diagram of the multi-sublayer circulation graphite-like carbon / molybdenum disulfide composite coating disclosed by the present application is shown in the figure.

[0035] Figure 2 A schematic diagram of a four-target unbalanced magnetron sputtering system for preparing the coating of Example 1 is shown in the figure.

[0036] Figure 3 A nanohardness comparison result graph of Example 1 and Comparative Example 1 of the present application is shown in the figure.

[0037] Figure 4 The average friction coefficient of Example 1 and Comparative Example 1 of the present application in a 50% RH humid atmosphere environment is shown in the figure. DETAILED DESCRIPTION

[0038] In order to enable personnel in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0039] It is to be understood that the terms "first", "second", and the like, used in the description and the claims of the application, as well as the above-described drawings, are used to distinguish between similar objects and are not necessarily used to describe a particular sequential or chronological order. It is to be understood that the use of the terms so-termed "first", "second", etc., can be interchanged with each other, where appropriate, such that the embodiments of the application described herein can be carried out in other than the order shown or described herein. Furthermore, the terms "comprising", "having", and any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or apparatus that comprises a list of steps or units can not necessarily be limited to those steps or units that are clearly recited, but can include other not explicitly recited steps or units, as well as steps or units that are inherent in such process, method, product, or apparatus.

[0040] The application will be further described in detail below with reference to the accompanying drawings:

[0041] Example 1

[0042] The method for preparing a multi-environmentally applicable multi-sublayer circulation graphite carbon / molybdenum disulfide composite coating on the surface of a bearing steel substrate comprises the following steps:

[0043] 1) Surface treatment of the bearing steel substrate

[0044] The surface of the substrate is subjected to grinding and polishing treatment, with a roughness of less than 0.1 μm; then, the substrate surface is ultrasonically cleaned with acetone and anhydrous ethanol solution for 15 min each, and dried with dry nitrogen.

[0045] 2) Argon ion etching

[0046] The bearing steel substrate after ion implantation treatment is installed on the side of the single-axis clamp of the four-target unbalanced magnetron sputtering system, and vacuumized to less than 1×10 -4 Pa, a bias voltage of -650 V is set, and the surface of the bearing steel substrate is subjected to argon ion etching, with an etching duration of 1800 s.

[0047] 3) Deposition of Cr adhesive layer

[0048] A high-purity chromium target installed in the four-target unbalanced magnetron sputtering system is used to deposit a chromium adhesive layer on the etched surface of the bearing steel substrate. The process parameters are: chromium target current 3.0 A, bias voltage -100 V, Ar gas flow rate 16 sccm, sample rotation speed 7 rpm, and deposition time 600 s.

[0049] 4) Deposition of gradient transition layer (Cr→Cr / a-C→a-C)

[0050] A gradient transition layer Cr→Cr / a-C→a-C was deposited on the surface of the chromium adhesive layer using a high-purity chromium target and a graphite target installed in a four-target unbalanced magnetron sputtering system. The process parameters were as follows: the chromium target current was linearly decreased from 3.0 A to 0 A, while the graphite target current was linearly increased from 0 A to 3.0 A, and the change time of each target current was 1200 s.

[0051] 5) Hard amorphous carbon layer deposition

[0052] A hard amorphous carbon layer was deposited on the surface of the gradient transition layer by controlling the graphite target sputtering current and bias voltage. The process parameters were as follows: the graphite target current was 3.5 A, the bias voltage was -150 V, and the deposition time was 1800 s.

[0053] 6) Multi-cycle sublayer GLC-S / GLC-MoS2 deposition

[0054] A nanoscale multi-sublayer cycle target layer was deposited on the surface of the hard amorphous carbon layer using a graphite target, a sulfur / carbon composite target, and a molybdenum disulfide target installed in a four-target unbalanced magnetron sputtering system by precisely controlling the sputtering current of each target and the sample rotation rate. The cycle was deposited for 180 periods. The process parameters were as follows: the graphite target current was 3.5 A, the sulfur / carbon composite target current was 2.0 A, the molybdenum disulfide target current was 1.0 A, the bias voltage was -60 V, the sample rotation rate was 1 rpm, and the deposition time was 10800 s.

[0055] 7) Graphite-like carbon top layer deposition

[0056] A graphite-like carbon top layer was deposited on the surface of the multi-sublayer cycle target layer. The process parameters were as follows: the graphite target current was 3.5 A, the sulfur / carbon composite target and the molybdenum disulfide target current were both 0 A, the bias voltage was -60 V, the sample rotation rate was 7 rpm, and the deposition time was 1200 s.

[0057] Through the above steps, a multi-environmentally applicable multi-sublayer cycle graphite-like carbon / molybdenum disulfide composite coating with a total thickness of about 2.5 μm was prepared on the surface of the bearing steel.

[0058] Example 2

[0059] A method for preparing a multi-environmentally applicable multi-sublayer cycle graphite-like carbon / molybdenum disulfide composite coating on the surface of a 304 stainless steel substrate, comprising the following steps:

[0060] 1) Surface treatment of the stainless steel substrate

[0061] The substrate surface was ground and polished to a roughness of less than 0.05 μm; then, the substrate surface was ultrasonically cleaned with acetone and anhydrous ethanol solution for 20 min each, and dried with dry nitrogen.

[0062] 2) Argon ion etching

[0063] The bearing steel substrate after ion implantation treatment was installed on the side of the single-axis clamp of the four-target unbalanced magnetron sputtering system, and vacuumized to below 1 × 10 -4 At 40 Pa, the bias voltage was set to -600 V, and the bearing steel substrate ion implantation surface was subjected to argon ion etching for 1200 s.

[0064] 3) Cr adhesive layer deposition

[0065] The chromium adhesive layer was deposited on the etched surface of the bearing steel substrate by using the high-purity chromium target installed in the four-target unbalanced magnetron sputtering system. The process parameters were: chromium target current 3.0 A, bias voltage -100 V, Ar gas flow rate 15 sccm, sample rotation speed 7 rpm, and deposition time 750 s.

[0066] 4) Gradient transition layer (Cr→Cr / a-C→a-C) deposition

[0067] The gradient transition layer Cr→Cr / a-C→a-C was deposited on the surface of the chromium adhesive layer by controlling the change of the current of each target over time. The process parameters were: the chromium target current was linearly decreased from 3.0 A to 0 A, while the graphite target current was linearly increased from 0 A to 3.0 A, and the change time of each target current was 1200 s.

[0068] 5) Hard amorphous carbon layer deposition

[0069] The hard amorphous carbon layer was deposited on the surface of the gradient transition layer. The process parameters were: graphite target current 3.5 A, bias voltage -180 V, and deposition time 2400 s.

[0070] 6) Multi-cycle sublayer GLC-S / GLC-MoS2 deposition

[0071] The multi-sublayer cycle target layer was deposited on the surface of the hard amorphous carbon layer by using the four-target unbalanced magnetron sputtering system to accurately control the sputtering current of each target and the sample rotation speed, and the cycle deposition was performed for 105 periods. The process parameters were: graphite target current 3.5 A, sulfur / carbon composite target current 2.5 A, molybdenum disulfide target current 0.8 A, bias voltage -70 V, sample rotation speed 0.5 rpm, and deposition time 12600 s.

[0072] 7) Graphite-like carbon top layer deposition

[0073] The graphite-like carbon top layer was deposited on the surface of the multi-sublayer cycle target layer. The process parameters were: graphite target current 3.0 A, sulfur / carbon composite target and molybdenum disulfide target current both 0 A, bias voltage -70 V, sample rotation speed 7 rpm, and deposition time 1800 s.

[0074] A multi-environmentally applicable multi-sublayer cyclic graphitic carbon / molybdenum disulfide composite coating with a total thickness of about 3.0 μm was prepared on the surface of 304 stainless steel by the above method.

[0075] Example 3

[0076] A method for preparing a multi-environmentally applicable multi-sublayer cyclic graphitic carbon / molybdenum disulfide composite coating on the surface of a surface metal-modified zirconia ceramic substrate comprises the following steps:

[0077] 1) Surface treatment of the zirconia ceramic substrate

[0078] The ceramic surface was polished to a roughness of less than 0.1 μm, and then sequentially ultrasonically cleaned with acetone and anhydrous ethanol solution for 15 min each, and the substrate surface was dried with dry nitrogen.

[0079] 2) Argon ion etching

[0080] The ion-implanted bearing steel substrate was installed on the side of a single-axis clamp of a four-target unbalanced magnetron sputtering system, and vacuumed to less than 1 x 10 -4 Pa, a bias voltage of -700 V was set, and the ion-implanted surface of the bearing steel substrate was subjected to argon ion etching for 1800 s.

[0081] 3) Deposition of a Cr adhesive layer

[0082] A high-purity chromium target installed in the four-target unbalanced magnetron sputtering system was used to deposit a chromium adhesive layer on the etched surface of the substrate. The process parameters were: chromium target current 3.0 A, bias voltage -100 V, Ar gas flow rate 15 sccm, sample rotation speed 7 rpm, and deposition time 900 s.

[0083] 5) Deposition of a gradient transition layer (Cr→Cr / a-C→a-C)

[0084] A high-purity chromium target and a graphite target installed in the four-target unbalanced magnetron sputtering system were used to deposit a gradient transition layer Cr→Cr / a-C→a-C by controlling the change of the current of each target with time. The process parameters were: the chromium target current was linearly decreased from 3.0 A to 0 A, while the graphite target current was linearly increased from 0 A to 3.0 A, and the change time of the current of each target was 900 s.

[0085] 4) Deposition of a gradient transition layer (Cr→Cr / a-C→a-C)

[0086] A gradient transition layer Cr→Cr / a-C→a-C was deposited on the surface of the chromium adhesive layer by controlling the change of the current of each target with time. The process parameters were: the chromium target current was linearly decreased from 3.0 A to 0 A, while the graphite target current was linearly increased from 0 A to 3.0 A, and the change time of the current of each target was 900 s.

[0087] 5) Hard amorphous carbon layer deposition

[0088] A hard amorphous carbon layer was deposited on the surface of the gradient transition layer. The process parameters were: graphite target current 3.5 A, bias voltage -130 V, sample rotation speed 7 rpm, and deposition time 1200 s.

[0089] 6) Multi-cycle sublayer GLC-S / GLC-MoS2 deposition

[0090] A multi-sublayer cycle target layer was deposited on the surface of the hard amorphous carbon layer by controlling the sputtering current of each target and the sample rotation speed, and the cycle deposition was performed for 180 cycles. The process parameters were: graphite target current 3.0 A, sulfur / carbon composite target current 2.0 A, molybdenum disulfide target current 0.8 A, bias voltage -70 V, sample rotation speed 1.2 rpm, and deposition time 9000 s.

[0091] 7) Graphite-like carbon top layer deposition

[0092] A graphite-like carbon top layer was deposited on the surface of the multi-sublayer cycle target layer. The process parameters were: graphite target current 3.5 A, sulfur / carbon composite target and molybdenum disulfide target current 0 A, bias voltage -70 V, sample rotation speed 7 rpm, and deposition time 900 s.

[0093] The above method prepared a multi-environmentally applicable multi-sublayer cycle graphite-like carbon / molybdenum disulfide composite coating with a total thickness of about 2.0 μm on the surface of the surface metallized zirconia ceramic substrate.

[0094] Comparative Example 1

[0095] A traditional MoS2 lubricating coating was prepared on the surface of a bearing steel substrate using a four-target magnetron sputtering system, including the following steps:

[0096] 1) Surface treatment of bearing steel substrate

[0097] The surface of the substrate was ground and polished to a roughness of less than 0.1 μm, and then sequentially ultrasonically cleaned with acetone and anhydrous ethanol solution for 15 min each, and the surface of the substrate was blown dry with dry nitrogen.

[0098] 2) Argon ion etching

[0099] The bearing steel substrate after ion implantation was installed on the side of the single-axis clamp of the four-target unbalanced magnetron sputtering system, and vacuumed to less than 1 × 10 -4 Pa, a bias voltage of -650 V was set, and the surface of the bearing steel substrate was ion implanted and argon ion etched for 1800 s.

[0100] 3) Cr adhesion layer deposition

[0101] A high purity chromium target was installed in a four-target unbalanced magnetron sputtering system to deposit a chromium adhesion layer on the etched surface of a bearing steel substrate. The process parameters were as follows: chromium target current 3.0 A, bias voltage -100 V, Ar gas flow rate 16 sccm, sample rotation speed 7 rpm, and deposition time 600 s.

[0102] 4) Preparation of a gradient transition layer (Cr→Cr / MoS2→MoS2)

[0103] A high purity chromium target and a molybdenum disulfide target were installed in a four-target unbalanced magnetron sputtering system to prepare a gradient transition layer Cr→Cr / MoS2→MoS2. The process flow was as follows: the chromium target current was linearly reduced from 3.0 A to 0 A, while the molybdenum disulfide target current was linearly increased from 0 A to 0.8 A, and the change time of each target current was 1200 s.

[0104] 5) Preparation of a MoS2 layer

[0105] A high purity molybdenum disulfide target was installed in a four-target unbalanced magnetron sputtering system to deposit a MoS2 layer on the surface of the gradient transition layer (Cr→Cr / MoS2→MoS2). The process parameters were as follows: molybdenum disulfide target current 0.8 A, bias voltage -60 V, and sample rotation speed 7 rpm.

[0106] Figure 1 A schematic diagram of the multi-environmentally applicable multi-sublayer cyclic graphite carbon / molybdenum disulfide composite coating structure of the present application is shown. Figure 2 The relative positions of the targets installed in the four-target unbalanced magnetron sputtering system used in Example 1 are shown.

[0107] As shown in Table 1, the nano-hardness comparison results of Example 1 and Comparative Example 1 are shown. The nano-indentation system was used for testing, and the testing depth was less than one-tenth of the film thickness to avoid the influence of the substrate. The results showed that the nano-hardness of Example 1 was 9.3 GPa, and the nano-hardness of Comparative Example 1 was 4.7 GPa. It can be seen that Example 1 has a higher nano-hardness than Comparative Example 1. Figure 3 As shown in Table 2, the average friction coefficient comparison of Example 1 and Comparative Example 1 under the same matching pairs and test parameters is shown. The results showed that under the conditions of 50% RH atmospheric environment, 5 N normal load, GCr15 matching pair (GCr15) (mm), the average friction coefficient of Example 1 was 0.035, and the average friction coefficient of Comparative Example 1 was 0.08. It indicated that Example 1 had better lubrication performance in a humid atmospheric environment.

[0108] Figure 4

[0109] ​​​In summary, the method disclosed by the application is prepared by using a multi-target magnetron sputtering system, and sequentially includes substrate surface treatment, deposition of a chromium metal bonding layer and a gradient transition layer (Cr→Cr / a-C→a-C) on the substrate surface, deposition of a high-hardness a-C support layer (a-C) on the surface of the gradient transition layer (Cr→Cr / a-C→a-C), deposition of a graphite-like carbon sublayer (GLC), a sulfur-doped graphite-like carbon sublayer (S / GLC) and a molybdenum disulfide sublayer (MoS2) on the surface of the a-C layer in sequence, and deposition of a graphite-like carbon top layer on the surface of the multi-cycle sublayer. The graphite-like carbon / molybdenum disulfide composite coating has excellent tribological properties in various environments such as vacuum, dry and humid atmosphere.

[0110] The above is only used for describing the technical idea of the application, and cannot be used to limit the protection scope of the application. Any modification made according to the technical idea of the application and based on the technical scheme falls within the protection scope of the claims of the application.

Claims

1. A multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating, characterized in that, The composite coating consists of a chromium metal bonding layer, a gradient transition layer, a hard amorphous carbon support layer, a multi-sublayer circulating target layer, and a graphite-like carbon top layer sequentially disposed on the substrate; wherein: The gradient transition layer is composed of a chromium-doped amorphous carbon layer with a linearly decreasing chromium content; The hard amorphous carbon support layer is composed of hydrogen-free amorphous carbon or high-hardness amorphous carbon with a hydrogen content of less than 10%, and its nanohardness is not less than 20 GPa. The multi-sublayer cyclic target layer comprises several layers, each of which is formed by the sequential deposition of a graphite-like carbon sublayer, a sulfur-doped graphite-like carbon sublayer, and a molybdenum disulfide sublayer from bottom to top. The modulation period of the multi-sublayer cyclic target layer is 4.5 nm to 30 nm. The percentage of sulfur atoms in the sulfur-doped graphite-like carbon sublayer is 2% to 10%.

2. The multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating according to claim 1, characterized in that, The total thickness of the composite coating is 1.0 μm to 6.0 μm.

3. The method for preparing the multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating according to claim 1 or 2, characterized in that, Includes the following steps: 1) Argon ion etching is performed on the surface of the dried substrate; 2) In Ar + A chromium metal bonding layer is deposited on the etched substrate surface; 3) Deposit a gradient transition layer of Cr→Cr / aC→aC on the surface of the chromium metal bonding layer; 4) Deposit a hard amorphous carbon support layer on the surface of the gradient transition layer; 5) A graphite-like carbon sublayer, a sulfur-doped graphite-like carbon sublayer, and a molybdenum disulfide sublayer are sequentially deposited on the surface of a hard amorphous carbon support layer to form a sublayer target layer. 6) Repeat step 5) several times until the multi-sublayer cyclic target layer is obtained; 7) Deposit a graphite-like carbon top layer on the surface of the multi-sublayer circulating target layer to complete the coating preparation.

4. The method for preparing the multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating according to claim 3, characterized in that, In step 1), the substrate is subjected to grinding, polishing, ultrasonic cleaning and drying treatments in sequence before etching, and the roughness Ra is reduced to less than 0.1 μm.

5. The method for preparing the multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating according to claim 3, characterized in that, In step 1), the process parameters for argon ion etching are: argon flow rate of 20 sccm to 40 sccm, substrate bias voltage of -600V to -750V, and duration of 1200s to 2400s; in step 2), the process parameters for depositing the chromium metal binder layer are: target current of 2.0A to 4.0A and substrate bias voltage of -60V to -100V.

6. The method for preparing the multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating according to claim 3, characterized in that, In step 3), a gradient transition layer is deposited on the surface of the chromium metal binder using a multi-target unbalanced magnetron sputtering system. The process parameters are as follows: the chromium target current is linearly reduced from 2.0A to 4.0A to 0A, while the graphite target current is linearly increased from 0A to 1.5A to 4.0A. The target current change time is 600s to 1800s, and the argon flow rate is 10sccm to 20sccm.

7. The method for preparing the multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating according to claim 3, characterized in that, In step 4), a hard amorphous carbon support layer is deposited on the surface of the gradient transition layer using a multi-target unbalanced magnetron sputtering system. The process parameters are: graphite target current 1.5A~4.0A, bias voltage -100V~-200V, argon flow rate 10sccm~25sccm, sample rotation speed 5rpm~10rpm, and the thickness of the hard amorphous carbon support layer is 0.3μm~1.0μm.

8. The method for preparing the multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating according to claim 3, characterized in that, In step 5), a multi-target unbalanced magnetron sputtering system is used to sequentially deposit a graphite-like carbon sublayer, a sulfur-doped graphite-like carbon sublayer, and a molybdenum disulfide sublayer on the surface of a hard amorphous carbon support layer. The process parameters are as follows: graphite target current is 1.5A to 4.0A, sulfur-graphite mixed target current is 2.0A to 4.0A, molybdenum disulfide target current is set to 0.5A to 1.5A, bias voltage is -60V to -120V, and sample rotation speed is 0.5rpm to 3rpm; the thickness of one sublayer is 1.5nm to 10nm.

9. The method for preparing a multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating according to claim 3, characterized in that, In step 7), a graphite-like carbon top layer is deposited on the surface of the multi-sublayer circulating target layer using multi-target magnetron sputtering. The process parameters are: graphite target current 1.5A~4.0A, bias voltage -60V~-100V, sample rotation speed 5rpm~10rpm, and thickness 0.1μm~0.5μm.

10. The application of the multi-sublayer circulating graphite carbon / molybdenum disulfide composite coating as described in claim 1 or 2 in the preparation of high-end aerospace equipment.

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