Ultra-slip diamond-like carbon-based coating, composite coating and preparation method thereof

Abstract

The present application relates to an ultra-slip diamond-like carbon-based coating, a composite coating, and a preparation method thereof. The diamond-like carbon-based coating comprises carbon, hydrogen, and doping elements, wherein the doping elements include a weak carbide-forming metal element, a strong carbide-forming metal element, and a non-metallic element. In the diamond-like carbon-based coating, the atomic percentage of carbon, based on the total atomic weight of carbon and doping elements, is 70% to 90%, the atomic percentage of the weak carbide-forming metal element, based on the total atomic weight of the doping elements, is 50% to 70%, and the atomic percentage of the strong carbide-forming metal element, based on the total atomic weight of the doping elements other than the weak carbide-forming metal element, is 50% to 80%. The coating preparation method comprises: performing pulsed magnetron sputtering deposition using a target containing the doping elements. The coating exhibits both a low coefficient of friction and high hardness, and can achieve ultra-slip properties under low-temperature, wide-temperature, and humid conditions.

Description

Technical Field

[0001] The present application relates to the technical field of solid lubricating coating material preparation, and in particular to a diamond-like carbon-based coating, a composite coating and a preparation method thereof. Background Art

[0002] With the continuous development of aviation and aerospace technology, large-scale equipment often faces the test of complex environments such as high and low temperatures and multiple atmospheres. These complex environments pose significant challenges to the lubrication of mechanical moving parts. Mechanical parts are affected by low temperatures and multiple atmospheres during operation in space, making oil and grease no longer ideal lubricants. Therefore, solid lubricants are often used in moving parts operating in such complex environments.

[0003] Diamond-like carbon-based coating is a common solid lubricant material, which is composed of graphite structure sp 2 Hybridized carbon atoms and sp in diamond structure 3 Hybrid carbon atoms are mixed with each other and usually have the characteristics of high hardness and low friction and wear. 2 、sp 3 Different ratios of hydrogen and hydrogen components can produce diamond-like carbon-based coatings with different properties. Therefore, hydrogen-containing diamond-like carbon-based coatings have a wide range of friction coefficients, hardness ranges, and temperature application ranges. Researchers have achieved super-slippery (friction coefficient less than 0.01) in diamond-like carbon-based coatings through methods such as hydrogen passivation, forming high-quality transfer films, shear localization, and adding two-dimensional material nano-additives. However, this super-slip state depends on a specific gas atmosphere and temperature range. It is difficult to achieve super-slippery in a humid atmosphere containing active oxygen molecules and water vapor, or at lower temperatures (as low as -80°C).

[0004] Element doping is a common method for improving the bonding strength, environmental adaptability, and friction performance of coatings, and it is promising. However, current single-element doping often negatively impacts one coating property while improving another: for example, while doping with Cr or Ti improves bonding strength, it often reduces the friction performance of the coating. Doping with Al or Ag reduces internal stress in the coating while also weakening its mechanical properties (such as hardness and elastic modulus). Diamond-like carbon-based coatings obtained through element doping in current research reports do not yet offer a balance between friction and mechanical properties, making it difficult to achieve the engineering application and promotion of ultra-slip diamond-like carbon-based coatings.

[0005] Therefore, how to prepare a diamond-like carbon-based coating that can achieve ultra-slippery properties in a low-temperature, wide-temperature range and humid atmosphere remains a key technical problem that needs to be solved urgently. Summary of the Invention

[0006] Based on this, it is necessary to provide a diamond-like carbon-based coating and its preparation method that can achieve super-slippery properties in a low temperature, wide temperature range and humid atmosphere, and can simultaneously have excellent friction and mechanical properties.

[0007] In one aspect of the present application, there is provided a diamond-like carbon-based coating, characterized in that the constituent elements include carbon, hydrogen and doping elements, wherein the doping elements include weak carbide-forming metal elements, strong carbide-forming metal elements and non-metallic elements;

[0008] In the diamond-like carbon-based coating, the atomic percentage content of carbon is 70% to 90% based on the total atomic amount of carbon, hydrogen and doping elements, the atomic percentage content of weak carbide-forming metal elements is 50% to 70% based on the total atomic amount of doping elements, and the atomic percentage content of strong carbide-forming metal elements is 50% to 80% based on the total atomic amount of doping elements other than the weak carbide-forming metal elements.

[0009] In one embodiment, the weak carbide-forming metal element is selected from any one of the following:

[0010] (a) Al;

[0011] (b) Combination of Al and Ag;

[0012] (c) Combination of Al and Au;

[0013] (d) Combination of Al and Cu;

[0014] The atomic percentage content of Al element in (b), (c) and (d) is 70% to 90%.

[0015] In some embodiments, the strong carbide-forming metal element is selected from at least one of Cr, Ti, and W.

[0016] In some embodiments, the non-metallic element is selected from Si.

[0017] Another aspect of the present application provides a composite coating, comprising:

[0018] a substrate bonding layer, arranged on the substrate;

[0019] a hard strengthening layer, arranged on the base bonding layer;

[0020] a gradient layer disposed on the hard reinforcement layer; and

[0021] a friction action layer, arranged on the gradient layer;

[0022] Wherein, the material of the hard strengthening layer is nitride, the material of the gradient layer is carbonitride with gradient carbon and nitrogen contents, and the friction effect layer is the diamond-like carbon-based coating.

[0023] In some embodiments, the composite coating further comprises at least one of the following technical features:

[0024] The material of the substrate bonding layer is any one of Cr, Ti, AlCrSi or AlTiSi;

[0025] The material of the hard strengthening layer is any one of nitrides of Cr, Ti, AlCrSi or AlTiSi.

[0026] In some embodiments, from the end close to the hard reinforcement layer to the end close to the friction interaction layer, the nitrogen content gradient of the transition layer material decreases to zero, and the carbon content gradient increases to the same as the carbon content in the friction interaction layer.

[0027] In some embodiments, the thickness of the friction effect layer is 50% to 80% of the thickness of the composite coating.

[0028] In some embodiments, the composite coating further comprises at least one of the following technical features:

[0029] The thickness of the substrate bonding layer is 300nm to 800nm;

[0030] The hard strengthening layer has a thickness of 100 nm to 300 nm;

[0031] The thickness of the gradient layer is 100nm to 300nm;

[0032] The thickness of the friction layer is 500nm to 2000nm.

[0033] In some embodiments, the friction coefficient of the composite coating is no more than 0.01 at 20°C and 0.5% relative humidity; the friction coefficient of the composite coating is no more than 0.01 at 20°C and 52% relative humidity; the friction coefficient of the composite coating is no more than 0.01 at -80°C in nitrogen.

[0034] In some embodiments, the nanohardness of the composite coating is not less than 9 GPa.

[0035] Another aspect of the present application provides a method for preparing a composite coating, wherein at least one of the substrate bonding layer, the hard strengthening layer, the gradient layer and the friction action layer is deposited by high-power pulsed magnetron sputtering.

[0036] In some embodiments, the sputtering deposition parameters are: pulse voltage 500V~900V, pulse length 50μs~200μs, pulse frequency 50Hz~200Hz, substrate bias voltage for preparing substrate bonding layer is 500V~900V, and substrate bias voltage for preparing hard strengthening layer, gradient layer and friction action layer is 50V~200V.

[0037] Compared with the prior art, this application has at least the following beneficial effects:

[0038] The diamond-like carbon-based coating provided by the present application has excellent friction and mechanical properties by adding a specific ratio of weak carbide-forming metal elements, strong carbide-forming metal elements and non-metallic elements. The weak carbide-forming metal elements can induce the coating to accelerate graphitization, that is, induce the carbon atoms in the coating to be sp 2 Hybrid structure (graphite structure), thereby obtaining a low friction coefficient, which also has the effect of reducing the internal stress of the coating and improving its toughness; and strong carbide-forming metal elements can induce carbon atoms in the coating to be sp 3 Hybrid structure (diamond structure), thereby obtaining high hardness; further, non-metallic elements can combine with water molecules to form low-shear hydrates, thereby reducing sensitivity to humid atmospheric environments. During the friction process, the hydrated silica gel formed by non-metallic elements preferentially combines with the grinding pair to form a transfer film, so that the oxidized weak carbide-forming metal elements and strong carbide-forming metal elements are separated from the grinding pair, and are gradually wrapped by the graphite layer on the surface of the transfer film to further reduce friction. Through the synergistic effect of a specific ratio of weak carbide-forming metal elements, strong carbide-forming metal elements and non-metallic elements, the friction coefficient of the diamond-like carbon-based coating can be reduced to an ultra-slip level in a low temperature, wide temperature range and humid atmospheric environment while also having high hardness.

[0039] This application further provides a composite coating comprising a sequentially stacked substrate bonding layer, a hard reinforcement layer, a gradient layer, and a diamond-like carbon-based coating. The layers exhibit good interface compatibility, enhancing the adhesion between the coating and the substrate and further improving the coating's mechanical properties. In particular, the doping elements in the surface diamond-like carbon-based coating are highly correlated with the primary elements in the composite coating's substrate bonding layer, hard reinforcement layer, and gradient layer. Rather than simply adding them together, they combine to improve bonding strength and friction performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0041] Figure 1 This is a schematic structural diagram of a composite coating according to one embodiment of the present application.

[0042] Reference numerals:

[0043] 100: Composite coating

[0044] 110: Matrix bonding layer; 120: Hard reinforcement layer; 130: Gradient layer; 140: Friction action layer. DETAILED DESCRIPTION

[0045] To facilitate understanding of the present application, a more comprehensive description of the present application will be provided below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0047] In this article, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0048] As used herein, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Furthermore, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0049] In this document, when referring to a range, if the unit is followed only by the right endpoint, it means that the units of the left and right endpoints are the same. For example, 0.3-0.5m / s means that the units of the left endpoint "0.3" and the right endpoint "0.5" are both m / s (meters per second).

[0050] Only certain numerical ranges are specifically disclosed herein. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, each individually disclosed point or single value may itself serve as a lower limit or upper limit and be combined with any other point or single value, or with other lower limits or upper limits, to form an unspecified range.

[0051] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0052] The term "weak carbide-forming metal element" refers to a metal element that has a slightly stronger chemical affinity with carbon than iron and thus forms less stable carbides.

[0053] The term "strong carbide-forming metal element" refers to a metal element that has a significantly stronger chemical affinity with carbon than iron, thereby forming stable carbides.

[0054] The term "atomic percentage content" refers to the percentage of atomic number, that is, the percentage of the number of atoms of a particular substance to the total amount of atoms of a specified substance.

[0055] The term "super-lubricant" refers to a coefficient of friction less than 0.01.

[0056] In one aspect, the present application provides a diamond-like carbon-based coating, the constituent elements of which include carbon, hydrogen, and a doping element. The doping element includes a weak carbide-forming metal element, a strong carbide-forming metal element, and a non-metallic element. In the diamond-like carbon-based coating, based on the total atomic content of carbon and the doping element, the atomic percentage content of carbon is 70% to 90%, based on the total atomic content of the doping element, the atomic percentage content of the weak carbide-forming metal element is 50% to 70%, and based on the total atomic content of the remaining doping elements other than the weak carbide-forming metal element, the atomic percentage content of the strong carbide-forming metal element is 50% to 80%.

[0057] In diamond-like carbon-based coatings, weak carbide-forming metal elements mainly exist in the form of metallic state, strong carbide-forming metal elements mainly exist in the form of metal carbide nanocrystals or metal solid solutions, and non-metallic elements mainly exist in the form of amorphous state.

[0058] Specifically, the diamond-like carbon-based coating is composed of an interpenetrating network. The interpenetrating network includes sp 3 A diamond-like carbon network of carbon connected in the form of sp 2 The carbon connected in the form of carbon, weak carbide-forming metal elements, strong carbide-forming metal elements and non-metallic elements are distributed in the above-mentioned interpenetrating network in the form of metal atoms and clusters, metal carbides and solid solutions, non-metallic carbides and amorphous networks, respectively.

[0059] In some embodiments, the weak carbide-forming metal element is Al. In some embodiments, the weak carbide-forming metal element is a combination of Al and Ag, wherein the atomic percentage content of Al in the combination of Al and Ag is 70% to 90%. In some embodiments, the weak carbide-forming metal element is a combination of Al and Au, wherein the atomic percentage content of Al in the combination of Al and Au is 70% to 90%. In some embodiments, the weak carbide-forming metal element is a combination of Al and Cu, wherein the atomic percentage content of Al in the combination of Al and Cu is 70% to 90%. Al can reduce the internal stress of the material and increase the toughness of the material, thereby inducing the coating to accelerate graphitization.

[0060] In some embodiments, the strong carbide-forming metal element is selected from at least one of Cr, Ti, or W. Cr, Ti, or W can improve interface compatibility with steel. Cr is more preferably selected. Cr and C form CrC nanocrystals, which increase the hardness of the coating and provide the coating with higher load-bearing capacity.

[0061] In some embodiments, the non-metallic element is selected from Si. The low-shear hydrated silica gel formed by the combination of Si element and water molecules can greatly improve the friction performance of the coating in a humid atmosphere.

[0062] Furthermore, the strong reactivity of Al, Cr and Si elements with oxygen has an important influence on the low shear graphite layer (sp 2 The indirect protection of the hybrid carbon grid reduces the coating's sensitivity to humid atmospheric environments and gives the coating a lower friction coefficient.

[0063] In some embodiments, the components of the diamond-like carbon-based coating include C, Si, Al, and Cr. During the friction process, the hydrated silica gel formed by the Si element preferentially combines with the grinding pair to form a transfer film, so that the oxidized Al and Cr elements (aluminum oxide, chromium oxide) are isolated from the grinding pair and gradually replaced by the graphite layer (sp) on the surface of the transfer film. 2 Hybrid carbon grid) wrapped around it to effectively reduce friction.

[0064] See also Figure 1 In another aspect, the present application provides a composite coating 100, comprising:

[0065] a substrate bonding layer 110 , arranged on the substrate 10 ;

[0066] A hard reinforcement layer 120 is arranged on the base bonding layer 110;

[0067] The gradient layer 130 is arranged on the hard reinforcement layer 120;

[0068] The friction effect layer 140 is arranged on the gradient layer 130 .

[0069] The material of the substrate bonding layer 110 has a strong bond with the substrate 10. In some embodiments, the material of the substrate bonding layer 110 can be any one of Cr, Ti, AlCrSi, or AlTiSi. The thickness of the substrate bonding layer 110 can be any value between 300 nm and 800 nm, for example, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, or 750 nm.

[0070] The material of the hard reinforcement layer 120 is a nitride, which has high hardness and can improve the mechanical strength of the composite coating and play a role in supporting high loads. In some embodiments, the material of the hard reinforcement layer 120 can be a nitride of any one of Cr, Ti, AlCrSi or AlTiSi. Preferably, the material of the hard reinforcement layer 120 is a nitride of the corresponding substrate bonding layer 110 material. For example, when the substrate bonding layer 110 material is Cr, the material of the hard reinforcement layer 120 is CrN; when the substrate bonding layer 110 material is Ti, the material of the hard reinforcement layer 120 is TiN; when the substrate bonding layer 110 material is AlCrSi, the material of the hard reinforcement layer 120 is AlCrSiN; when the substrate bonding layer 110 material is AlTiSi, the material of the hard reinforcement layer 120 is AlTiSiN. The thickness of the hard reinforcement layer 120 can be any value between 100nm and 300nm, for example, it can also be 150nm, 200nm, or 250nm.

[0071] The gradient layer 130 is made of a carbonitride with a gradient of carbon and nitrogen contents. In some embodiments, the nitrogen content of the gradient layer 130 decreases to zero from the end near the hard reinforcement layer 120 to the end near the friction layer 140, while the carbon content increases to the same level as the carbon content in the friction layer 140. The thickness of the gradient layer 130 can be anywhere between 100 nm and 300 nm, for example, 150 nm, 200 nm, or 250 nm.

[0072] The friction effect layer 140 is a diamond-like carbon-based coating according to any of the above embodiments. The thickness of the friction effect layer 140 is at least half of the thickness of the composite coating 100 , preferably 50% to 80% of the thickness of the composite coating 100 . Specifically, the thickness of the friction action layer 120 can be any value between 500nm and 2000nm, for example, it can also be 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, 1000nm, 1050nm, 110nm, 1150nm, 1200nm, 1250nm, 1300nm, 1350nm, 1400nm, 1450nm, 1500nm, 1550nm, 1600nm, 1650nm, 1700nm, 1750nm, 1800nm, 1850nm, 1900nm, or 1950nm.

[0073] In some embodiments, the composite coating 100 is composed of a substrate bonding layer 110 , a hard reinforcement layer 120 , a gradient layer 130 , and a friction interaction layer 140 stacked in sequence.

[0074] In some embodiments, the composite coating 100 has a friction coefficient of no more than 0.01 at 20°C and 0.5% relative humidity; the composite coating 100 has a friction coefficient of no more than 0.01 at 20°C and 52% relative humidity; and the composite coating 100 has a friction coefficient of no more than 0.01 at -80°C in nitrogen.

[0075] In some embodiments, the composite coating has a hardness of not less than 9 GPa at 100 nm.

[0076] In another aspect, the present application further improves a method for preparing a composite coating, wherein at least one of the substrate bonding layer 110, the hard reinforcement layer 120, the gradient layer 130, and the friction interaction layer 140 is deposited by high-power pulsed magnetron sputtering. This method has the characteristics of high ionization rate and good plating performance, can better facilitate parameterized control of the deposition process, and can be extended to industrial production applications.

[0077] In some embodiments, the sputtering deposition parameters are: pulse voltage 500V~900V, pulse length 50μs~200μs, pulse frequency 50Hz~200Hz, substrate bias voltage for preparing substrate bonding layer is 500V~900V, and substrate bias voltage for preparing hard strengthening layer, gradient layer and friction action layer is 50V~200V.

[0078] In some embodiments, the method for preparing the composite coating comprises:

[0079] (a) placing the substrate to be processed and the target material corresponding to the substrate bonding layer in a pulsed magnetron sputtering device, introducing an inert gas under vacuum conditions, and sputtering and depositing the substrate bonding layer;

[0080] (b) introducing nitrogen gas, increasing the gas pressure, and sputtering and depositing a hard strengthening layer;

[0081] (c) gradually reducing the nitrogen flow rate while gradually increasing the flow rate of the carbon source gas to increase the gas pressure and sputter-deposit the gradient layer;

[0082] (d) The target material is replaced with a target material doped with elements in a diamond-like carbon-based coating, and the friction effect layer is sputtered and deposited.

[0083] In some embodiments, the substrate is pretreated. The pretreatment step may include conventional pretreatment steps such as solvent cleaning, polishing, and glow cleaning. For example, step (e) mechanically polishes the substrate to a surface roughness of less than 400 nm; step (f) ultrasonically cleans the polished substrate using ethanol, acetone, and deionized water, respectively; and step (g) cleans the substrate in a pulsed magnetron sputtering apparatus, introduces an inert gas at a pressure of 1.0 to 2.5 Pa, and maintains a bias voltage of 600 to 1000 V.

[0084] In some embodiments, the gas pressure in step (a) is 1.0 Pa to 2.5 Pa.

[0085] In some embodiments, the gas pressure in step (b) is increased by 0.3 Pa to 0.6 Pa.

[0086] In some embodiments, the gas pressure in step (c) is increased by 0.05 Pa to 0.2 Pa.

[0087] In some embodiments, the gas pressure in step (d) is increased by 0.2 Pa to 0.4 Pa.

[0088] In some embodiments, in step (a), the substrate bonding layer is deposited at a substrate bias voltage of 600-1000 V for 5-10 minutes.

[0089] In some embodiments, in step (c), the flow rate of nitrogen is reduced to zero, and the flow rate of the carbon source gas is increased to the same as the carbon content in the friction interaction layer.

[0090] The following are specific examples. They are intended to further explain this application in detail to help those skilled in the art and researchers further understand it. The relevant technical conditions, etc., do not constitute any limitation on this application. Any modifications made within the scope of the claims of this application are within the scope of protection of the claims of this application.

[0091] Unless otherwise noted, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods. All instruments are conventionally selected in the art. Experimental methods not specified in the examples were performed under conventional conditions, such as those described in literature or books, or methods recommended by the manufacturer.

[0092] Example 1

[0093] (1) Substrate pretreatment

[0094] The surface of GCr15 stainless steel was mechanically polished to a surface roughness of 50 nm to 100 nm, and then the polished stainless steel was ultrasonically cleaned with ethanol, acetone and deionized water for 15 min respectively.

[0095] (2) Glow cleaning

[0096] The cleaned stainless steel was quickly blown dry and fixed on the bracket inside the coating chamber, and then vacuumed to a vacuum degree better than 5×10 -3 Pa, then introduce argon gas to keep the cavity pressure at 1.4 Pa, turn on the bias power supply, set the bias voltage to 900 V, and the working time is 20 min.

[0097] (3) Preparation of substrate bonding layer

[0098] Cr was selected as the target material for the substrate bonding layer, the gas flow rate of argon was changed to keep the gas pressure in the cavity at 0.45 Pa, the high-power pulsed magnetron sputtering power supply was turned on, the pulse voltage was set to 600 V, the pulse length was 100 μs, the pulse frequency was 200 Hz, the substrate bias was set to 800 V, the working time was 5 min, and the layer thickness was 500 nm.

[0099] (4) Preparation of hard reinforcement layer

[0100] The same target material as in step (3) was selected, the gas flow rate of argon remained unchanged, and nitrogen was introduced at the same time. The gas pressure in the chamber was increased to 0.52 Pa. The high-power pulse magnetron sputtering power supply was kept at the same settings and turned on. The substrate bias was maintained at 100 V, the working time was 3 minutes, and the layer thickness was 200 nm.

[0101] (5) Gradient layer preparation

[0102] On the basis of maintaining the working parameters of step (4), the nitrogen flow rate was gradually reduced to zero, and acetylene gas was gradually introduced until the pressure in the cavity increased by 0.8 Pa. The whole time lasted for 3 minutes, and the thickness of the layer was 200 nm.

[0103] (6) Preparation of friction layer

[0104] An AlCrSi composite target 1 (Al:Cr:Si=6:3:1) was used as the element-doped target. The same parameters of the high-power pulsed magnetron sputtering power supply as in step (5) were maintained, the substrate bias voltage remained unchanged, the working time was 15 min, and the thickness was 1500 nm. A diamond-like carbon-based coating doped with Al, Cr, and Si elements was obtained. Energy spectrometer detection showed that the atomic percentages of C, Al, Cr, and Si in the layer were 82 at.%, 12 at.%, 4 at.%, and 2 at.%, respectively.

[0105] Example 2

[0106] The preparation method is basically the same as that in Example 1, except that, in the preparation process of the friction action layer in step (6), an AlCrSi composite target 1 and an Ag single element target are used as element-doped targets. The Ag target uses a high-power pulsed magnetron sputtering power supply, and its pulse voltage is set to 500 V, the pulse length is 100 μs, and the pulse frequency is 200 Hz to obtain a diamond-like carbon-based coating doped with Al, Ag, Cr and Si elements. After detection by an energy spectrometer, the atomic percentages of C, Al, Cr, Si and Ag in the layer are 78 at.%, 14 at.%, 4 at.%, 3 at.% and 1 at.%, respectively.

[0107] Example 3

[0108] The preparation method is essentially the same as that of Example 2, except that, during step (6) of preparing the friction interaction layer, the substrate bias voltage is increased to 200 V, resulting in a diamond-like carbon-based coating doped with Al, Ag, Cr, and Si. Energy dispersive spectrometer analysis revealed that the atomic percentages of C, Al, Cr, Si, and Ag in the layer were 79 at.%, 14 at.%, 4 at.%, 5 at.%, 3 at.%, and 1 at.%, respectively.

[0109] Comparative Example 1

[0110] The preparation method is basically the same as that of Example 1, except that step (4) and step (5) are omitted.

[0111] Comparative Example 2

[0112] The preparation method is essentially the same as that of Example 1, except that AlCrSi composite target 1 is replaced with AlCrSi composite target 2 (Al:Cr:Si = 3:6:1). The atomic percentages of C, Al, Cr, and Si in the prepared diamond-like carbon-based coating are 82 at.%, 4 at.%, 12 at.%, and 2 at.%, respectively.

[0113] Comparative Example 3

[0114] The preparation method is essentially the same as that of Example 1, except that the AlCrSi composite target 1 is replaced with an AlSi composite target (Al:Si = 9:1). The atomic percentages of C, Al, and Si in the prepared diamond-like carbon-based coating are 82 at.%, 14 at.%, and 4 at.%, respectively.

[0115] The friction coefficient and hardness of the composite coatings of Examples 1 to 3 and Comparative Examples 1 to 3 were measured:

[0116] 1. Friction coefficient: The friction coefficient was tested by a ball-on-disc friction test, wherein the disc was 9Cr18 stainless steel with the composite coating prepared on the surface, the ball was a 9Cr18 stainless steel ball with a diameter of 6 mm, the ball-on-disc rotation speed was 100 rpm (corresponding to a linear velocity of 0.21 m / s), and the load was 8 N (corresponding to a contact stress of 1.3 GPa). The friction coefficients were measured at room temperature (20°C), in the atmosphere, and at a relative humidity of 0.5%; at room temperature (20°C), in the atmosphere, and at a relative humidity of 52%; and at a low temperature of -80°C and in a nitrogen environment.

[0117] 2. Hardness: Nanohardness is tested by nanohardness tester (refer to GB / T 25898-2010 for testing).

[0118] 3. Adhesion: Test the adhesion by a scratch tester (refer to JB / T 8554-1997 for testing).

[0119] The results are shown in Table 1:

[0120] Table 1

[0121]

[0122] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0123] The embodiments described above only express several implementation methods of the present application, which are convenient for understanding the technical solutions of the present application in a specific and detailed manner, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all fall within the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description and drawings can be used to interpret the content of the claims.

Claims

1. A composite coating, characterized in that: include: a substrate bonding layer, arranged on the substrate; a hard strengthening layer, arranged on the base bonding layer; a gradient layer, arranged on the hard strengthening layer; as well as a friction action layer, arranged on the gradient layer; Wherein, the material of the hard strengthening layer is nitride, the material of the gradient layer is carbonitride with gradient carbon and nitrogen content, and the friction layer is a diamond-like carbon-based coating; The constituent elements of the diamond-like carbon-based coating include carbon, hydrogen and doping elements, and the doping elements include weak carbide-forming metal elements, strong carbide-forming metal elements and non-metallic elements; In the diamond-like carbon-based coating, the atomic percentage content of carbon is 70% to 90% based on the total atomic amount of carbon and doping elements, the atomic percentage content of weak carbide-forming metal elements is greater than 50% and less than 70% based on the total atomic amount of doping elements, and the atomic percentage content of strong carbide-forming metal elements is 50% to 80% based on the total atomic amount of doping elements other than the weak carbide-forming metal elements. The strong carbide-forming metal element is selected from at least one of Cr, Ti or W; The non-metallic element is selected from Si; The weak carbide-forming metal element is selected from any one of the following: (a) Al; (b) a combination of Al and Ag; (c) a combination of Al and Au; (d) a combination of Al and Cu; wherein the atomic percentage content of Al in (b), (c) and (d) is 70% to 90%; The diamond-like carbon-based coating is composed of an interpenetrating network, and the interpenetrating network includes sp 3 The diamond-like carbon network is formed by carbon atoms connected in a sp 2 formally linked carbons; The preparation method of the diamond-like carbon-based coating comprises: using a target material containing the doping element to perform pulsed magnetron sputtering deposition, wherein the sputtering deposition parameters are: pulse voltage 500V to 900V, pulse length 50μs to 200μs, and pulse frequency 50Hz to 200Hz; The material of the substrate bonding layer is any one of Cr, Ti, AlCrSi or AlTiSi; The material of the hard strengthening layer is any one of nitrides of Cr, Ti, AlCrSi or AlTiSi; From the end close to the hard reinforcement layer to the end close to the friction interaction layer, the nitrogen content of the gradient layer material decreases to zero, and the carbon content increases to the same as the carbon content in the friction interaction layer. The thickness of the friction layer is 500nm to 2000nm. The composite coating has a friction coefficient of no more than 0.01 at 20°C and a relative humidity of 0.5%; a friction coefficient of no more than 0.01 at 20°C and a relative humidity of 52%; and a friction coefficient of no more than 0.01 at -80°C in nitrogen. The nanohardness of the composite coating is not less than 9 GPa and not more than 10.5 GPa.

2. The composite coating according to claim 1, characterized in that The thickness of the friction effect layer is 50% to 80% of the thickness of the composite coating.

3. The composite coating according to claim 2, characterized in that Also includes at least one of the following technical features: The thickness of the substrate bonding layer is 300nm to 800nm; The hard strengthening layer has a thickness of 100 nm to 300 nm; The thickness of the gradient layer is 100nm to 300nm.

4. A method for preparing a composite coating according to any one of claims 1 to 3, characterized in that: At least one of the matrix bonding layer, the hard strengthening layer, the gradient layer and the friction effect layer is made by high-power pulsed magnetron sputtering deposition.

5. The method for preparing the composite coating according to claim 4, characterized in that: The substrate bias voltage for preparing the substrate bonding layer is 500V to 900V, and the substrate bias voltage for preparing the hard strengthening layer, gradient layer and friction action layer is 50V to 200V.

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