Composite protective coating and preparation method therefor

Abstract

Disclosed in the present invention is a composite protective coating, comprising an AlCrYN layer, a CrAlNx layer and a CrN layer, which are sequentially arranged from top to bottom, wherein in the AlCrYN layer, the atomic percent content of each element is as follows: N: 30-50%, Al: 25-40%, Cr: 20-30%, and Y: 0.2-7%; the AlCrYN layer is of a face-centered cubic structure and has a (200) preferred orientation; the texture coefficient (TC) is 0.5-0.7; the grain size is 20-180 nm; and a Y solid solution is formed in an AlCrN crystal lattice. Further provided in the present invention is a preparation method for the composite protective coating. Compared with the prior art, the AlCrYN coating prepared by means of a technique used in the present invention has good uniformity, crystal grains in the coating are fine, and there are few crystal defects; and the coating has a good friction coefficient and hydrophobicity, and is reduced in terms of adhesion with molten aluminum. In the present invention, the thickness of the coating can be controlled by controlling the coating time. The present invention is simple and efficient, saves on materials and conforms to the environmental protection concept of sustainable development. The coating has the potential of being applied to the field of molten aluminum contact on a large scale, and can produce huge social and economic benefits.

Description

Composite protective coating and preparation method thereof Technical Field

[0001] The invention belongs to the technical field of surface treatment, and particularly relates to a composite protective coating and a preparation method thereof. Background Art

[0002] Aluminum and aluminum alloy components are widely used in aerospace, automobile, food, and electronic manufacturing due to their low density, good mechanical properties, excellent fatigue and corrosion resistance, and good electrical conductivity.

[0003] Hot molten aluminum is highly corrosive. During the aluminum manufacturing process, materials in direct contact with the molten aluminum, such as molds and crucibles, are subject to corrosion, melting loss, adhesion, and wear. Damage to these materials can lead to molten aluminum contamination, increased production costs, reduced product performance, and decreased production efficiency.

[0004] Currently, surface enhancement techniques can be used to improve substrate surface properties, thereby enhancing their service performance. PVD technology is widely used due to its environmental friendliness and minimal substrate deformation. AlCrN coatings, produced by arc ion plating, are a type of ternary cemented carbide coating that boasts high hardness and strong bonding properties. At high temperatures, they readily form a high-temperature corrosion-resistant Al2O3 phase on the surface, thereby slowing the inward diffusion of oxygen. However, AlCrN coatings exhibit high internal stress, poor wear resistance, a high friction coefficient, and are prone to adhesion to molten aluminum at high temperatures, limiting their application.

[0005] Y is a chemically active rare earth element. TC Rojas et al. successfully prepared AlCrYN coatings with different Al and Y contents by setting different Y target powers. They found that due to the reactive element effect, Y can inhibit the upward diffusion of Fe in the substrate and Cr in the coating, making it easier for the coating to generate a denser and more oxidation-resistant Al2O3 layer at high temperature, rather than a looser (Al,Cr)2O3 layer.

[0006] Currently, reports on AlCrYN coatings focus primarily on their high-temperature oxidation resistance, with less attention paid to improvements in mechanical protection and surface wettability. Furthermore, preparation methods typically rely on controlling target power and coating content, a cumbersome process with long coating cycles and low economic efficiency. Furthermore, single-layer AlCrYN coatings exhibit poor bonding properties and are prone to separation or flaking from the substrate, leading to coating failure.

[0007] Summary of the Invention

[0008] The object of the present invention is to provide a composite protective coating with fine grains inside the coating, few crystal defects, excellent friction coefficient, excellent hydrophobicity, and reduced adhesion to aluminum liquid.

[0009] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a composite protective coating, comprising an AlCrYN layer, a CrAlNx layer and a CrN layer arranged in sequence from top to bottom, wherein the atomic percentage content of each element in the AlCrYN layer is as follows: N: 30-50%, Al: 25-40%, Cr: 20-30%, Y: 0.2-7%, the AlCrYN layer has a face-centered cubic structure with a (200) preferred orientation, a texture coefficient TC of 0.5-0.7, a grain size of 20-180nm, and a Y solid solution formed in the AlCrN lattice.

[0010] The composite protective coating provided by the present invention has a three-layer structure, in which the CrN transition layer is responsible for achieving strong bonding and high toughness functions, the CrAlNx gradient hard support layer achieves high hardness and impact resistance, and the AlCrYN coating achieves wear-resistant lubrication, hydrophobicity and anti-liquid aluminum adhesion functions. According to the Hall-Petch effect, the smaller the grain, the higher the hardness of the coating. Through the solid solution of the Y element, the grain size of the AlCrYN layer is reduced, thereby improving the hardness of the coating. At the same time, the solid solution of the Y element causes the AlCrYN layer to generate a Cr2O3 phase and an Al2O3 amorphous-encapsulated nanocrystalline structure during the friction process. The Cr2O3 phase has a lubricating effect, and the Al2O3 amorphous-encapsulated nanocrystalline structure can prevent the flash temperature friction during the friction process from oxidizing the coating, thereby damaging the coating.

[0011] Preferably, the thickness ratio of the CrN layer to the CrAlNx layer is 1:(2-5), and the thickness ratio of the CrAlNx layer to the AlCrYN layer is (1-2):1. The thickness ratio of the three-layer coating in the present invention has a very important influence on the bonding, friction performance and wettability of the material. By regulating the thickness ratio of the three layers, the surface energy of the coating can be effectively controlled, thereby effectively improving its hydrophobicity. Among them, the thickness ratio of the CrN layer to the CrAlNx layer affects the bonding performance of the coating. The CrN layer, as a transition layer, can effectively be compatible with the Fe and Cr elements in the mold steel, and the CrAlN layer, as a hard support layer, can increase the hardness of the coating and prevent the coating from peeling. By regulating the thickness ratio of the two layers, the bonding, hardness and toughness of the coating can be simultaneously improved. The thickness ratio of the CrAlNx layer to the AlCrYN layer affects the friction performance and wettability of the coating. As a hard supporting layer, the CrAlNx layer can effectively improve the friction performance of the coating by increasing its hardness. The AlCrYN layer can generate a lubricating Cr2O3 phase during the friction process, which can also improve the friction performance of the coating. However, the ratio of the AlCrYN layer to the CrAlNx layer should not be too high, otherwise the overall hardness of the coating will decrease, thus affecting the friction performance. Surface free energy is a key factor affecting the wettability of solid surfaces, and surface free energy is affected by composition, preferred orientation, and microstructure. By adjusting the thickness ratio of the CrAlNx layer to the AlCrYN layer, the CrAlNx layer does not form a completely cubic structure, but a mixed structure of cubic and tetragonal phases, which causes the preferred orientation of the AlCrYN layer to change from (111) to (200), affecting the change in the wettability of the coating.

[0012] Preferably, the CrAlNx layer has a mixed structure of cubic and tetragonal phases, and the mass percentage of nitrogen in the CrAlNx layer is 10-35%. The low nitrogen content results in insufficient bonding of Cr, Al, and nitrogen in the CrAlNx layer, preventing the complete formation of a face-centered cubic structure, with some tetragonal phases forming.

[0013] Preferably, the thickness of the composite protective coating is 0.8-10 μm, the friction coefficient of the composite protective coating is 0.25-0.35, and the contact angle of the composite protective coating with water is 110-125°. Within the above thickness selection range, not only can the obtained composite coating have basic wear resistance and hydrophobicity, but also the economic benefits are maximized, which is conducive to industrial production and application.

[0014] Another object of the present invention is to provide a method for preparing a composite protective coating, which specifically comprises the following steps:

[0015] S1. Place the substrate in a vacuum chamber under vacuum atmosphere and etch the substrate surface using argon ions;

[0016] S2. In a vacuum atmosphere, a cathode arc coating device is used, with a Cr single target as the arc target and N2 as the reaction gas to provide the N element, to deposit a CrN transition layer on the surface of the substrate;

[0017] S3. In a vacuum atmosphere, using a cathode arc coating device, using a CrAl composite target as an arc target and N2 as a reaction gas to provide nitrogen elements, a CrAlNx layer is deposited on the surface of the CrN layer obtained in step S2;

[0018] S4. Under vacuum atmosphere, using a cathode arc coating device, with a CrAl composite target and a CrY composite target as arc targets, and N2 as a reaction gas to provide N element, an AlCrYN layer is deposited on the surface of the CrAlNx layer obtained in step S3 to obtain a composite protective coating.

[0019] Preferably, in step S1, the etching conditions are as follows: the working atmosphere is argon, the flow rate is 30-50 sccm, and the vacuum degree during sputtering is 2.0×10 -5 -4.0×10 -5 Torr, the substrate is preheated to 100-350°C, the deposition bias is -50V to -150V, the linear anode ion source current is 0.2-0.3A, and the substrate sputtering cleaning time is 30-90 minutes. The present invention etches the substrate before depositing the CrN layer, effectively removing the loose layer and oxide scale on the substrate surface. This is equivalent to atomic-level micro-shot peening, activating the substrate surface, improving the film-substrate bonding strength, and also providing efficient pre-ionization for subsequent coating.

[0020] Preferably, in step S2, the conditions for depositing the CrN transition layer are as follows: the working atmosphere is N2, the N2 flow rate is 200-550 sccm, and the pressure is controlled at 30-50 mTorr. Excessive pressure will result in too low kinetic energy of the CrN layer, while too low pressure will result in insufficient plasma concentration, making film formation difficult. The current is 60-90 A, the substrate is preheated to 100-400°C, the deposition bias is -50 V to -500 V, the deposition time is 10-90 min, and the target spacing between the substrate and the Cr target is 10-15 cm. By adjusting the appropriate target surface spacing, the coating can have a faster film formation rate and better film quality, and reduce the generation of large particles by the arc target during the deposition process.

[0021] Preferably, in step S3, the conditions for depositing the CrAlNx layer are as follows: the working atmosphere is N2, the flow rate of N2 is 150-350sccm, the controlled gas pressure is 35-85mTorr, the current is 60-90A, the substrate is preheated to 100-400°C, the deposition bias is -50V to -500V, too low a bias voltage will result in a slow coating deposition rate, but too high a bias voltage will cause excessive compressive stress generated during the deposition process, thereby causing the coating to crack, the deposition time is 60-360min, and the atomic percentage of the elements in the CrAl composite target is Cr:Al=30:70. This element ratio is selected because the generated CrAlNx has a high Al content, resulting in extremely high hardness. At the same time, the Al element exceeds this element ratio and is prone to generate harmful Hcp-AlN phase, thereby reducing the hardness of CrAlNx. The target spacing between the substrate and the CrAl composite target is 15-20cm.

[0022] Preferably, in step S4, the conditions for depositing the AlCrYN layer are as follows: a working atmosphere of N2, an N2 flow rate of 300-650 sccm, a controlled gas pressure of 35-85 mTorr, a substrate preheating to 100-400°C, a deposition bias voltage of -50 V to -500 V, a current of 60-90 A, and a deposition time of 60-360 min. The atomic percentage of the elements in the CrAl composite target is Cr:Al = 30:70, and the atomic percentage of the elements in the CrY composite target is Cr:Y = 90:10. The AlCrYN layer produced under these atomic percentages has optimal phase stability and is less susceptible to element segregation and decomposition. The target spacing between the substrate and the CrY composite target and the CrAl composite target is 15-20 cm.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The composite protective coating produced using the technology employed in this invention exhibits excellent uniformity, fine grains within the coating, and few crystal defects. It also exhibits an excellent coefficient of friction and excellent hydrophobicity, reducing adhesion to molten aluminum. The coating thickness can be controlled by controlling the coating time. Finally, the invention is simple, efficient, and material-efficient, aligning with the environmentally friendly concept of sustainable development. The coating has the potential for large-scale application in areas where contact with molten aluminum is required, potentially generating significant social and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is an XRD structure diagram of the composite protective coating prepared in Example 1 of the present invention;

[0026] FIG2 is a surface morphology and a cross-sectional morphology of the composite protective coating prepared in Example 1 of the present invention;

[0027] FIG3 is a friction curve diagram of the composite protective coating prepared in Example 1 of the present invention and the composite coating prepared in Comparative Example 1;

[0028] FIG4 is a contact angle between the composite coating prepared in Comparative Example 1 of the present invention and water;

[0029] FIG5 is a diagram showing the contact angle between the composite protective coating prepared in Example 1 of the present invention and water. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not intended to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between the intermediate value within any stated value or stated range and any other stated value or intermediate value within the stated range is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope. Without departing from the scope or spirit of the present invention, various modifications and variations can be made to the specific embodiments of the present invention description, which will be apparent to those skilled in the art. Other embodiments obtained from the description of the present invention will be apparent to those skilled in the art. This application description and examples are exemplary only.

[0032] An embodiment of the present invention provides a composite protective coating, comprising an AlCrYN layer, a CrAlNx layer and a CrN layer arranged in sequence from top to bottom. In the AlCrYN layer, the atomic percentage content of each element is as follows: N: 30-50%, Al: 25-40%, Cr: 20-30%, Y: 0.2-7%. The AlCrYN layer has a face-to-cubic structure with a (200) preferred orientation, a texture coefficient TC of 0.5-0.7, a grain size of 20-180 nm, and a Y solid solution formed in the AlCrN lattice.

[0033] The composite protective coating provided by the present invention has a three-layer structure, in which the CrN transition layer is responsible for achieving strong bonding and high toughness functions, the CrAlNx gradient hard support layer achieves high hardness and impact resistance, and the AlCrYN coating achieves wear-resistant lubrication, hydrophobicity and anti-liquid aluminum adhesion functions. According to the Hall-Petch effect, the smaller the grain, the higher the hardness of the coating. Through the solid solution of the Y element, the grain size of the AlCrYN layer is reduced, thereby improving the hardness of the coating. At the same time, the solid solution of the Y element causes the AlCrYN layer to generate a Cr2O3 phase and an Al2O3 amorphous-encapsulated nanocrystalline structure during the friction process. The Cr2O3 phase has a lubricating effect, and the Al2O3 amorphous-encapsulated nanocrystalline structure can prevent the flash temperature friction during the friction process from oxidizing the coating, thereby damaging the coating.

[0034] In a specific embodiment, the thickness ratio of the CrN layer to the CrAlNx layer is 1:(2-5), and the thickness ratio of the CrAlNx layer to the AlCrYN layer is (1-2): 1. By regulating the thickness ratio of the three layers, the surface energy of the coating can be effectively controlled, thereby effectively improving its hydrophobic properties.

[0035] In a specific embodiment, the CrAlNx layer has a cubic and tetragonal mixed structure, and the mass percentage of the N element in the CrAlNx layer is 10-35%.

[0036] In a specific embodiment, the thickness of the composite protective coating is 0.8-10 μm, the friction coefficient of the composite protective coating is 0.25-0.35, and the contact angle of the composite protective coating with water is 110-125°.

[0037] Another object of the present invention is to provide a method for preparing a composite protective coating, which specifically comprises the following steps:

[0038] S1. Place the substrate in a vacuum chamber under vacuum atmosphere and etch the substrate surface with argon ions. The etching conditions are as follows: the working atmosphere is argon gas with a flow rate of 30-50 sccm and a vacuum degree of 2.0×10 -5 -4.0×10 -5 Torr, substrate preheated to 100-350 ° C, deposition bias voltage was -50 V to -150 V, linear anode ion source current was 0.2-0.3 A, and substrate sputter cleaning time was 30-90 min;

[0039] S2. In a vacuum atmosphere, a cathode arc coating device is used, with a Cr target as the arc target and N2 as the reaction gas to provide the nitrogen element, to deposit a CrN transition layer on the surface of the substrate. The conditions for depositing the CrN transition layer are as follows: the working atmosphere is N2, the flow rate of N2 is 200-550 sccm, the pressure is controlled to be 30-50 mTorr, the current is 60-90 A, the substrate is preheated to 100-400°C, the deposition bias is -50 V to -500 V, the deposition time is 10-90 min, and the target distance between the substrate and the Cr target is 10-15 cm;

[0040] S3. In a vacuum atmosphere, a cathodic arc coating device is used, with a CrAl composite target as the arc target and N2 as the reaction gas to provide nitrogen element, to deposit a CrAlNx layer on the surface of the CrN layer obtained in step S2. The conditions for depositing the CrAlNx layer are as follows: a working atmosphere of N2, an N2 flow rate of 150-350 sccm, a controlled gas pressure of 35-85 mTorr, a current of 60-90 A, the substrate is preheated to 100-400° C., a deposition bias of -50 V to -500 V, and a deposition time of 60-360 min. The atomic percentage of the elements in the CrAl composite target is Cr:Al=30:70, and the target distance between the substrate and the CrAl composite target is 15-20 cm.

[0041] S4. Under a vacuum atmosphere, using a cathode arc coating device, with a CrAl composite target and a CrY composite target as arc targets, and N2 as a reaction gas to provide N element, an AlCrYN layer is deposited on the surface of the CrAlNx layer obtained in step S3 to obtain a composite protective coating. The conditions for depositing the AlCrYN layer are as follows: the working atmosphere is N2, the N2 flow rate is 300-650sccm, the gas pressure is controlled to be 35-85mTorr, the substrate is preheated to 100-400°C, the deposition bias is -50V to -500V, the current is 60-90A, and the deposition time is 60-360min. The atomic percentage of the elements in the CrAl composite target is Cr:Al=30:70, and the atomic percentage of the elements in the CrY composite target is Cr:Y=90:10. The target distances between the substrate and the CrY composite target and the CrAl composite target are both 15-20cm.

[0042] In a specific embodiment, the substrate is selected from one of H13 steel, 8407 steel and SKD61 steel.

[0043] The technical effects of the present invention are described below with reference to specific embodiments.

[0044] Example 1

[0045] In this embodiment, the substrate is H13 steel with a grade of 4Cr5MoSiV1, and the composite protective coating on the substrate surface is prepared as follows:

[0046] S1. Place the cleaned, degreased and dried substrate into the chamber, parallel to the top edge of the CrAl target in the vertical direction and 12.53 cm in the horizontal direction. Wait until the vacuum pressure in the chamber reaches 3.0×10 -5 Below 100 Torr, 33.2 sccm of argon gas was introduced into the vacuum chamber, the linear anode ion source current was set to 0.2 A, the substrate bias voltage was set to -200 V, and the 100°C substrate was etched with ionized argon ions for 30 min;

[0047] S2. In 550 sccm N2, the gas valve was controlled to 50 mTorr, the temperature was 200°C, a Cr element target was installed on the arc source as a Cr source, the target power was 1.0 kW, the current was 70 A, the deposition time was 10 min, the substrate bias voltage was -500 V, and during the coating deposition process, the substrate was rotated at a constant speed in the chamber to obtain a CrN transition layer;

[0048] S3. In 250 sccm N2, the gas valve was controlled to 35 mTorr, the temperature was 200°C, a CrAl target was installed on the arc source, the target power was 1.0 kW, the current was 60 A, the deposition bias was -50 V, and the deposition time was 60 min. During the deposition process, the substrate was rotated at a constant speed in the chamber to obtain a CrAlNx layer.

[0049] S4. In 650 sccm of N2, the gas valve was controlled to 80 mTorr, the temperature was 200°C, a CrAl target and a CrY target were installed on the arc source, the target power was 1.0 kW, the current was 60 A, and the deposition was performed for 60 minutes. During the deposition of the coating, the substrate was rotated at a constant speed in the cavity to obtain an AlCrYN layer.

[0050] FIG1 is an XRD diagram of the composite protective coating prepared in this embodiment, FIG2 is a surface morphology diagram and a cross-sectional morphology diagram of the composite protective coating prepared in this embodiment, wherein FIG2a is a surface morphology diagram of the composite protective coating prepared in this embodiment, FIG2b is a cross-sectional morphology diagram of the composite protective coating prepared in this embodiment, FIG3 is a friction curve diagram of the composite protective coating prepared in this embodiment and the composite coating prepared in Comparative Example 1, and FIG5 is a contact angle between the composite protective coating prepared in this embodiment and water; It can be seen from FIG1, FIG2, FIG3, FIG5 and the relevant test results that the composite protective coating of this embodiment has a The total thickness is 3.83 μm, and the thickness ratio is approximately CrN:CrAlNx:AlCrYN=1:3:3. The Cr content of the innermost layer of the coating is 51.64 at.%, and the N content is 48.36 at.%. The Al content of the middle layer is 19.63 at.%, the Cr content is 39.05 at.%, and the N content is 41.32 at.%. The Al content of the outermost layer is 38.00 at.%, the Cr content is 20.05 at.%, and the N content is 41.32 at.%. The Y content is 0.63 at.%. The bonding strength between the composite protective coating and the substrate is 85.9 N. The friction coefficient of the composite protective coating at room temperature is 0.27. The CrAlNx layer of the composite protective coating has a mixed structure of cubic and tetragonal phases. The texture coefficient of the composite protective coating (200) is 0.69. The contact angle of the composite protective coating with water is 125°.

[0051] Example 2

[0052] In this embodiment, the substrate is H13 steel with a grade of 4Cr5MoSiV1, and the composite protective coating on the substrate surface is prepared as follows:

[0053] S1. Place the cleaned, degreased and dried substrate into the cavity. The vertical height is 3.5 cm lower than the top edge of the CrAl target and the horizontal distance is 12.53 cm. Wait until the vacuum pressure in the cavity reaches 3.0×10 -5 Below 100 Torr, 33.2 sccm of argon gas was introduced into the vacuum chamber, the linear anode ion source current was set to 0.2 A, the substrate bias voltage was set to -200 V, and the 200°C substrate was etched with ionized argon ions for 30 min;

[0054] S2. In 550 sccm N2, the gas valve was controlled to 50 mTorr, the temperature was 200°C, a Cr element target was installed on the arc source as a Cr source, the target power was 1.0 kW, the current was 70 A, the deposition time was 10 min, the substrate bias voltage was -150 V, and during the coating deposition process, the substrate was rotated at a constant speed in the chamber to obtain a CrN transition layer;

[0055] S3. In 250 sccm N2, the gas valve was controlled to 35 mTorr, the temperature was 200°C, a CrAl target was installed on the arc source, the target power was 1.0 kW, the current was 60 A, and the deposition was carried out for 60 min. During the deposition of the coating, the substrate was rotated at a constant speed in the chamber to obtain a CrAlNx layer.

[0056] S4. In 650 sccm of N2, the gas valve is controlled to 80 mTorr, the temperature is 200°C, a CrAl target and a CrY target are installed on the arc source, the target power is 1.0 kW, the current is 60 A, the deposition time is 60 min, the deposition bias is -500 V, and during the deposition of the coating, the substrate is rotated at a constant speed in the cavity to obtain an AlCrYN layer.

[0057] After testing, the total thickness of the composite protective coating in this embodiment is 3.56 μm, and the thickness ratio is approximately CrN:CrAlNx:AlCrYN=1:3:3. The Cr element content of the innermost layer of the composite protective coating is 54.92 at.%, and the N element content is 45.08 at.%. The Al element content of the middle layer is 18.04 at.%, the Cr element content is 38.05 at.%, and the N element content is 43.91 at.%. The Al element content of the outermost layer is 36.05 at.%, the Cr element content is 17.08 at.%, and the N element content is 40.74 at.%. The Y element content is 6.13 at.%. The bonding strength between the composite protective coating and the substrate is 71.6 N. The friction coefficient of the composite protective coating at room temperature is 0.39. The CrAlNx layer of the composite protective coating has a mixed structure of cubic and tetragonal phases. The texture coefficient of the composite protective coating (200) is 0.57. The contact angle of the composite protective coating with water is 118°.

[0058] Example 3

[0059] In this embodiment, the substrate is 8407 steel, and the composite protective coating on the substrate surface is prepared as follows:

[0060] S1. Place the cleaned, degreased and dried substrate into the chamber, parallel to the top edge of the CrAl target in the vertical direction and 12.53 cm in the horizontal direction. Wait until the vacuum pressure in the chamber reaches 3.0×10 -5 Below 100 Torr, 33.2 sccm of argon gas was introduced into the vacuum chamber, the linear anode ion source current was set to 0.2 A, the substrate bias voltage was set to -200 V, and the 350°C substrate was etched with ionized argon ions for 30 min;

[0061] S2. In 550 sccm N2, the gas valve was controlled to 50 mTorr, the temperature was 200°C, a Cr element target was installed on the arc source as a Cr source, the target power was 1.0 kW, the current was 70 A, the deposition time was 10 min, the substrate bias voltage was -200 V, and during the coating deposition process, the substrate was rotated at a constant speed in the chamber to obtain a CrN transition layer;

[0062] S3. In 250 sccm N2, the gas valve was controlled to 35 mTorr, the temperature was 200°C, a CrAl target was installed on the arc source, the target power was 1.0 kW, the deposition bias was -250 V, the current was 60 A, and the deposition was carried out for 90 min. During the deposition of the coating, the substrate was rotated at a constant speed in the chamber to obtain a CrAlNx layer.

[0063] S4. In 650 sccm N2, the gas valve was controlled to 80 mTorr, the temperature was 200°C, a CrAl target and a CrY target were installed on the arc source, the target power was 1.0 kW, the current was 60 A, and the deposition was performed for 90 minutes. During the deposition of the coating, the substrate was rotated at a constant speed in the cavity to obtain an AlCrYN layer.

[0064] After testing, the total thickness of the composite protective coating of this embodiment is 5.31 μm, and the thickness ratio is approximately CrN:CrAlNx:AlCrYN=1:5:5. The Cr element content of the innermost layer of the composite protective coating is 51.73 at.%, and the N element content is 48.27 at.%. The Al element content of the middle layer is 19.83 at.%, the Cr element content is 32.91 at.%, and the N element content is 47.26 at.%. The Al element content of the outermost layer is 34.97 at.%, the Cr element content is 20.62 at.%, and the N element content is 43.62 at.%. The Y element content is 0.79 at.%. The bonding strength between the composite protective coating and the substrate is 82.5 N, the friction coefficient of the composite protective coating at room temperature is 0.29, the CrAlNx layer of the composite protective coating is a mixed structure of cubic and tetragonal phases, the texture coefficient of the composite protective coating (200) is 0.52, and the contact angle of the composite protective coating with water is 110°.

[0065] Example 4

[0066] In this embodiment, the substrate is H13 steel with a grade of 4Cr5MoSiV1, and the composite protective coating on the substrate surface is prepared as follows:

[0067] S1. Place the cleaned, degreased and dried substrate into the chamber, parallel to the top edge of the CrAl target in the vertical direction and 12.53 cm in the horizontal direction. Wait until the vacuum pressure in the chamber reaches 3.0×10 -5Below 100 Torr, 33.2 sccm of argon gas was introduced into the vacuum chamber, the linear anode ion source current was set to 0.2 A, the substrate bias voltage was set to -200 V, and the 200°C substrate was etched with ionized argon ions for 30 min;

[0068] S2. In 550 sccm N2, control the gas valve to 50 mTorr, the temperature to 200°C, install a Cr element target on the arc source as a Cr source, the target power is 1.0 kW, the current is 70 A, the deposition is carried out for 10 minutes, the substrate bias voltage is -50 V, and during the deposition process, the substrate is rotated at a constant speed in the chamber to obtain a CrN transition layer;

[0069] S3. In 250 sccm N2, the gas valve was controlled to 35 mTorr, the temperature was 200°C, a CrAl target was installed on the arc source, the target power was 1.0 kW, the current was 60 A, the deposition bias was -50 V, and the deposition was carried out for 120 min. During the deposition of the coating, the substrate was rotated at a constant speed in the chamber to obtain a CrAlNx layer.

[0070] S4. In 650 sccm of N2, the gas valve was controlled to 80 mTorr, the temperature was 200°C, a CrAl target and a CrY target were installed on the arc source, the target power was 1.0 kW, the current was 60 A, and the deposition was performed for 60 minutes. During the deposition of the coating, the substrate was rotated at a constant speed in the cavity to obtain an AlCrYN layer.

[0071] After testing, the total thickness of the composite protective coating prepared in this embodiment is 4.97um, and the thickness ratio is approximately CrN:CrAlNx:AlCrYN=1:4:2. The Cr element content of the innermost layer of the composite protective coating is 50.25at.%, and the N element content is 49.75at.%; the Al element content of the middle layer is 19.66at.%, the Cr element content is 30.71at.%, and the N element content is 49.63at.%; the Al element content of the outermost layer is 34.63at.%, the Cr element content is 20.85at.%, and the N element content is 43.74at.%; and the Y element content is 0.78at.%. The bonding strength between the composite protective coating and the substrate is 75.4N, the friction coefficient of the composite protective coating at room temperature is 0.34, the CrAlNx layer of the composite protective coating is a mixed structure of cubic and tetragonal phases, the texture coefficient of the composite protective coating (200) is 0.56, and the contact angle between the composite protective coating and water is 110°.

[0072] Comparative Example 1

[0073] In this comparative example, the substrate is H13 steel with a grade of 4Cr5MoSiV1. The specific preparation process of the composite coating of this comparative example is as follows:

[0074] S1. Place the cleaned, degreased and dried substrate into the cavity and wait until the vacuum pressure in the cavity reaches 3.0×10 -5 Below 100 Torr, 33.2 sccm of argon gas was introduced into the vacuum chamber, the linear anode ion source current was set to 0.2 A, the substrate bias voltage was set to -200 V, and the substrate was etched with ionized argon ions for 30 min;

[0075] S2. In 550 sccm N2, the gas valve was controlled to 50 mTorr, the temperature was 200°C, a Cr element target was installed on the arc source as a Cr source, the target power was 1.0 kW, the current was 70 A, and the deposition was carried out for 10 minutes. During the deposition process, the substrate was rotated at a constant speed in the chamber to obtain a CrN transition layer.

[0076] S3. In 650 sccm N2, the gas valve was controlled to 80 mTorr, the temperature was 200°C, a CrAl target was installed on the arc source, the target power was 1.0 kW, the current was 60 A, and the deposition was performed for 120 min. During the coating deposition process, the substrate was rotated at a constant speed in the cavity to obtain an AlCrN layer.

[0077] Figure 3 is a friction curve diagram of the composite protective coating prepared in Example 1 of the present invention and the composite coating prepared in Comparative Example 1, and Figure 4 is a contact angle between the composite coating prepared in this comparative example and water; it can be concluded from Figures 3, 4 and related test results that the total thickness of the composite coating in this comparative example is 3.14um, the Al element content in the composite coating is 14.80at.%, the Cr element content is 39.37at.%, and the N element content is 45.83at.%; the bonding strength between the composite coating and the substrate is 68.9N, the friction coefficient of the composite coating at room temperature is 0.45, the composite coating (111) texture coefficient is 0.86, and the contact angle between the composite coating and water is 70°. It can be seen from the results of Example 1 and this comparative example that the AlCrYN coating plays an indispensable role in the three-layer composite coating of the present invention and directly affects the physical and mechanical properties of the composite coating.

[0078] Comparative Example 2

[0079] In this comparative example, the substrate is H13 steel with a grade of 4Cr5MoSiV1. The specific preparation process of the composite coating of this comparative example is as follows:

[0080] S1. Place the cleaned, degreased and dried substrate into the chamber. The vertical height difference between the substrate and the top edge of the CrAl target is 5.5 cm and the horizontal distance is 12.53 cm. Wait until the vacuum pressure in the chamber reaches 3.0×10 -5Below 100 Torr, 33.2 sccm of argon gas was introduced into the vacuum chamber, the linear anode ion source current was set to 0.2 A, the substrate bias voltage was set to -200 V, and the substrate was etched with ionized argon ions for 30 min;

[0081] S2. In 550 sccm N2, the gas valve was controlled to 50 mTorr, the temperature was 200°C, a Cr element target was installed on the arc source as a Cr source, the target power was 1.0 kW, the current was 70 A, and the deposition was carried out for 10 minutes. During the deposition process, the substrate was rotated at a constant speed in the chamber to obtain a CrN transition layer.

[0082] S3. In 250 sccm N2, the gas valve was controlled to 35 mTorr, the temperature was 200°C, a CrAl target was installed on the arc source, the target power was 1.0 kW, the current was 60 A, and the deposition was carried out for 60 min. During the deposition of the coating, the substrate was rotated at a constant speed in the chamber to obtain a CrAlNx layer.

[0083] S4. In 650 sccm of N2, the gas valve was controlled to 80 mTorr, the temperature was 200°C, a CrAl target and a CrY target were installed on the arc source, the target power was 1.0 kW, the current was 60 A, and the deposition was performed for 60 minutes. During the deposition of the coating, the substrate was rotated at a constant speed in the cavity to obtain an AlCrYN layer.

[0084] After testing, the total thickness of the composite coating prepared in this comparative example is 3.76um, the thickness ratio is approximately CrN:CrAlNx:AlCrYN=1:3:3, the Cr element content of the innermost layer of the coating is 51.55at.%, and the N element content is 48.45at.%; the Al element content of the middle layer is 19.03at.%, the Cr element content is 39.02at.%, and the N element content is 41.95at.%; the Al element content of the outermost layer is 35.65at.%, the Cr element content is 18.19at.%, and the N element content is 37.62at.%; and the Y element content is 8.54at.%. The bonding strength between the composite coating and the substrate is 67.7N, the friction coefficient of the composite coating at room temperature is 0.40, the CrAlNx layer of the composite coating is a mixed structure of cubic and tetragonal phases, the texture coefficient of the composite coating (200) is 0.47, the texture coefficient of the composite coating (111) is 0.55, and the contact angle between the composite coating and water is 87°. It can be seen from the results of Example 1 and this comparative example that the doping amount of the Y element has an impact on the performance of the composite coating. When the content of the Y element is not within the range of the present invention, the mechanical properties and hydrophobic properties of the obtained composite coating are reduced.

[0085] Comparative Example 3

[0086] In this comparative example, the substrate is H13 steel with a grade of 4Cr5MoSiV1. The specific preparation process of the composite coating of this comparative example is as follows:

[0087] S1. Place the cleaned, degreased and dried substrate into the chamber. The vertical height difference between the substrate and the top edge of the CrAl target is 5.5 cm and the horizontal distance is 12.53 cm. Wait until the vacuum pressure in the chamber reaches 3.0×10 -5 Below 100 Torr, 33.2 sccm of argon gas was introduced into the vacuum chamber, the linear anode ion source current was set to 0.2 A, the substrate bias voltage was set to -200 V, and the substrate was etched with ionized argon ions for 30 min;

[0088] S2. In 550 sccm N2, the gas valve was controlled to 50 mTorr, the temperature was 200°C, a Cr element target was installed on the arc source as a Cr source, the target power was 1.0 kW, the current was 70 A, and the deposition was carried out for 5 minutes. During the deposition process, the substrate was rotated at a constant speed in the chamber to obtain a CrN transition layer.

[0089] S3. In 250 sccm N2, the gas valve was controlled to 35 mTorr, the temperature was 200°C, a CrAl target was installed on the arc source, the target power was 1.0 kW, the current was 60 A, and the deposition was carried out for 120 min. During the deposition of the coating, the substrate was rotated at a constant speed in the chamber to obtain a CrAlNx layer.

[0090] S4. In 650 sccm of N2, the gas valve was controlled to 80 mTorr, the temperature was 200°C, a CrAl target and a CrY target were installed on the arc source, the target power was 1.0 kW, the current was 60 A, and the deposition was performed for 60 minutes. During the deposition of the coating, the substrate was rotated at a constant speed in the cavity to obtain an AlCrYN layer.

[0091] After testing, the total thickness of the composite coating in this comparative example is 4.87um, and the thickness ratio is approximately CrN:CrAlNx:AlCrYN=1:8:4. The Cr element content of the innermost layer of the composite coating is 50.15at.%, and the N element content is 49.85at.%; the Al element content of the middle layer is 20.85at.%, the Cr element content is 33.22at.%, and the N element content is 45.93at.%; the Al element content of the outermost layer is 37.65at.%, the Cr element content is 17.00at.%, and the N element content is 40.62at.%; and the Y element content is 4.73at.%. The bonding strength between the composite coating and the substrate is 62.5N, the friction coefficient of the composite coating at room temperature is 0.43, the CrAlNx layer of the composite coating is a mixed structure of cubic and tetragonal phases, the composite coating (111) texture coefficient is 0.67, and the contact angle of the composite coating with water is 80°. It can be seen from the results of Example 1 and this comparative example that the thickness of the three-layer coating directly affects the performance of the composite coating finally obtained by the present invention. In this comparative example, CrN:CrAlNx:AlCrYN=1:8:4, and the bonding strength of the obtained composite coating decreases while the hydrophobicity also decreases.

[0092] In summary, the present invention adopts CrN coating, CrAlNx coating and AlCrYN coating, and rationally configures the Y element doping content and the thickness of the three-layer coating to obtain a composite protective coating with excellent friction coefficient and hydrophobicity, as well as bonding strength with the substrate.

[0093] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A composite protective coating, characterized in that: It includes an AlCrYN layer, a CrAlNx layer and a CrN layer arranged in sequence from top to bottom. In the AlCrYN layer, the atomic percentage content of each element is as follows: N: 30-50%, Al: 25-40%, Cr: 20-30%, Y: 0.2-7%. The AlCrYN layer is a face-centered cubic structure with a (200) preferred orientation, a texture coefficient TC of 0.5-0.7, a grain size of 20-180nm, and a Y solid solution is formed in the AlCrN lattice. The thickness ratio of the CrN layer to the CrAlNx layer is 1:(2-5), and the thickness ratio of the CrAlNx layer to the AlCrYN layer is (1-2):

1.

2. The composite protective coating according to claim 1, characterized in that: The CrAlNx layer is a mixed structure of cubic and tetragonal phases, and the mass percentage of N element in the CrAlNx layer is 10-35%.

3. The composite protective coating according to claim 1, characterized in that: The thickness of the composite protective coating is 0.8-10 μm, the friction coefficient of the composite protective coating is 0.25-0.35, and the contact angle between the composite protective coating and water is 110-125°.

4. A method for preparing a composite protective coating according to any one of claims 1 to 3, characterized in that: The preparation method specifically comprises the following steps: S1. Under vacuum atmosphere, placing the substrate in a vacuum chamber, and etching the surface of the substrate using argon ions; S2. In a vacuum atmosphere, a cathode arc coating device is used, a Cr single target is used as an arc target, and N2 is used as a reaction gas to provide N elements to deposit a CrN transition layer on the surface of the substrate; S3, in a vacuum atmosphere, using a cathode arc coating device, using a CrAl composite target as an arc target, and N2 as a reaction gas to provide N elements, to deposit a CrAlNx layer on the surface of the CrN layer obtained in step S2; S4. Under vacuum atmosphere, using a cathode arc coating device, with CrAl composite target and CrY composite target as arc targets, and N2 as a reaction gas to provide N element, an AlCrYN layer is deposited on the surface of the CrAlNx layer obtained in step S3 to obtain a composite protective coating.

5. The method for preparing the composite protective coating according to claim 4, characterized in that: In step S1, the etching conditions are as follows: the working atmosphere is argon gas, the flow rate is 30-50 sccm, and the vacuum degree during sputtering is 2.0×10 -5 -4.0×10 -5 Torr, the substrate is preheated to 100-350°C, the deposition bias is -50V to -150V, the linear anode ion source current is 0.2-0.3A, and the substrate sputtering cleaning time is 30-90min.

6. The method for preparing the composite protective coating according to claim 4, characterized in that: In the step S2, the conditions for depositing the CrN transition layer are as follows: the working atmosphere is N2, the flow rate of N2 is 200-550sccm, the gas pressure is controlled to be 30-50mTorr, the current is 60-90A, the substrate is preheated to 100-400°C, the deposition bias is -50V to -500V, the deposition time is 30-90min, and the target distance between the substrate and the Cr target is 10-15cm.

7. The method for preparing the composite protective coating according to claim 4, characterized in that: In the step S3, the conditions for depositing the CrAlNx layer are as follows: the working atmosphere is N2, the flow rate of N2 is 150-350sccm, the gas pressure is controlled to be 40-85mTorr, the current is 60-90A, the substrate is preheated to 100-400°C, the deposition bias is -50V to -500V, the deposition time is 60-360min, the atomic percentage of the elements in the CrAl composite target is Cr:Al=30:70, and the target distance between the substrate and the CrAl composite target is 15-20cm.

8. The method for preparing the composite protective coating according to claim 4, characterized in that: In the step S4, the conditions for depositing the AlCrYN layer are as follows: the working atmosphere is N2, the flow rate of N2 is 300-650sccm, the gas pressure is controlled to be 40-85mTorr, the substrate is preheated to 100-400°C, the deposition bias is -50V to -500V, the current is 60-90A, the deposition time is 60-360min, the atomic percentage of the elements in the CrAl composite target is Cr:Al=30:70, the atomic percentage of the elements in the CrY composite target is Cr:Y=90:10, and the target spacing between the substrate and the CrY composite target and the CrAl composite target is 15-20cm.

Images