CN117947381A - TiZrNbTa-based high-entropy nitride coating and preparation method thereof - Google Patents

Abstract

The invention discloses a TiZrNbTa-based high-entropy nitride coating which is characterized in that the chemical formula of the TiZrNbTa-based high-entropy nitride coating is Ti _aZr_bNb_cTa_dM_eN_f, wherein M is Mo or Cr or V or W, the atomic percentages of all elements are that a is more than or equal to 10 and less than or equal to 18, b is more than or equal to 10 and less than or equal to 18, c is more than or equal to 10 and less than or equal to 18, d is more than or equal to 10 and less than or equal to 18, e is more than or equal to 10 and less than or equal to 18, f is more than or equal to 10 and less than or equal to 50, and a+b+c+d+e+f=100. The coating has higher strength and toughness. The invention also discloses a preparation method of the TiZrNbTa-based high-entropy nitride coating.

Description

A TiZrNbTa-based high-entropy nitride coating and preparation method thereof

Technical Field

The invention belongs to the technical field of surface coatings, and in particular relates to a TiZrNbTa-based high-entropy nitride coating and a preparation method thereof.

Background technique

Lightweight alloys (Ti, Al) are widely used in aerospace, marine, automotive, and electronic manufacturing industries due to their low density, good mechanical properties, and easy processing. Especially for the automotive industry, lightweighting is an important development direction in the future, and the demand for lightweight alloy materials will increase greatly in the future.

However, the reliability of lightweight alloy materials such as titanium alloys faces major challenges in harsh service environments such as road gravel impact, friction and wear, acid, alkali and salt corrosion. In particular, automotive chassis parts such as clutches, transmissions, drive shafts, half shafts, screws, bolts, bearings and other moving parts are prone to corrosion and wear failure due to external environmental factors, and effective surface protection is urgently needed.

At present, the use of high-value, multifunctional and green PVD surface coating material technology is a technical approach to break through the performance limits of traditional metal materials and achieve high performance, long life and reliable service in harsh and complex environments.

At present, binary and ternary transition metal nitrides (TMN), such as TiN, CrN, and CrAlN coatings, are widely used due to their high melting point, thermal stability, and high hardness. However, the intrinsic brittleness of traditional TMN coatings often causes cracks and failures, limiting their application in harsh environments. In recent years, the rise of high entropy alloys has provided new ideas for the design of high-performance surface protective coatings.

Complex alloys with multiple principal components composed of five or more elements in equal or nearly equal molar ratios exhibit high entropy effect, slow diffusion effect, lattice distortion effect and "cocktail effect" in performance. These effects make it easy to form a single-phase solid solution structure, overcome the limitations of single-element alloying, and enable the alloy to obtain excellent comprehensive properties. Introducing nitrogen into high-entropy alloy coatings can obtain high-entropy nitride ceramic coatings.

The patent application with publication number CN105734312A discloses a biomedical TiZrNbTa high entropy alloy and a preparation method thereof. The chemical formula of the high entropy alloy is (TiaZrb)x(NbcTad)yMz, and the atomic percentages of the various components are: 0≤a≤35at%, 0≤b≤35at%, 0≤c≤35at%, 0≤d≤35at%, a+b＝x, c+d＝y, 5≤x≤70at%, 5≤y≤70at%, M is any one or more of V, Mo, Sn, W, Mn, Al, Fe, Co, Ni, Cu, Cr and Zn, 0≤z≤35at%, and x+y+z＝100. However, the alloy structure is a coarse columnar crystal structure, and the strength and toughness still have room for improvement.

The high entropy nitride coatings reported so far are mainly loose and coarse columnar crystal structures, and the intrinsic brittleness of the nitride ceramic phase and other problems make it insufficiently tough and cannot meet the requirements of high strength and toughness integration. In addition, it is difficult to obtain a dense, strong film-based coating at room temperature using traditional nitride coating preparation methods such as arc ion plating. The prepared coatings inevitably have some defects, which become the key technical bottleneck limiting their application.

Summary of the invention

The invention provides a TiZrNbTa-based high-entropy nitride coating, which has higher strength and toughness.

The invention provides a TiZrNbTa-based high-entropy nitride coating. The chemical formula of the TiZrNbTa-based high-entropy nitride coating is Ti _a Zr _b Nb _c Ta _{d Me} N _f , wherein M is Mo or Cr or V or W, the atomic percentage of each element is 10≤a≤18, 10≤b≤18, 10≤c≤18, 10≤d≤18, 10≤e≤18, 10≤f≤50, and a+b+c+d+e+f=100.

The present invention provides a higher content of N element, so that the metal element provided by the present invention and having a higher bonding strength with N forms more covalent bonds with the N element, thereby improving the mechanical properties of the coating. In addition, since the present invention provides Ta and M elements with a high valence electron concentration to form multiple metal components, the content of metal bonds is guaranteed, which helps to achieve toughening of the hard coating.

Preferably, the microstructure of the TiZrNbTa-based high entropy nitride coating is a face-centered cubic structure with a (111) preferred orientation.

Due to the appropriate amount of N element provided by the present invention, the structure of the coating provided by the present invention is a face-centered cubic structure, which is beneficial to provide the density and hardness of the coating, while inhibiting the initiation and expansion of cracks, thereby providing the hardness, toughness and wear resistance of the coating provided by the present invention.

Furthermore, the coating provided by the present invention has a (111) preferred orientation, which can inhibit the growth of cracks and increase the strength of the coating compared with other orientations.

Preferably, the atomic percentage of the N element is 40≤f≤50. Under this N element content, the hardness of the surface coating is 20-22GPa, the size of the radial crack is 3.8-4.2μm under a force of 50mN, and the coating exhibits high strength and toughness. The main reason is that the high nitrogen content promotes the formation of a single-phase FCC nitride phase in the coating, as well as the solid solution strengthening effect of the multi-metal components, while the (111) preferred orientation can effectively inhibit crack propagation and improve its toughness.

Preferably, the atomic percentage of the N element is 10≤f≤25. At this N element content, the hardness of the surface coating is 28-32GPa, and the size of the radial crack is 3-3.5μm under a force of 50mN. The TiZrNbTa-based high entropy nitride coating at this nitrogen content has optimal mechanical properties, and its toughening mechanism can be attributed to the grain refinement and solid solution strengthening brought about by the introduction of an appropriate amount of N element and the formation of a multi-component metal nitride hard phase.

Preferably, the high entropy nitride coating is nanocrystalline or amorphous nanocrystalline, and the grain size is 5-100 nm.

Preferably, the thickness of the TiZrNbTa-based high entropy nitride coating is 1-5 μm. At a suitable thickness, (111)-oriented grains are easily grown in the coating, thereby improving the strength and toughness of the coating.

The present invention also provides a method for preparing the TiZrNbTa-based high entropy nitride coating, comprising:

S1, cleaning and drying the substrate, and performing plasma glow etching treatment on the dried substrate using ionized argon gas to obtain a pretreated substrate;

S2. Depositing the TiZrNbTa-based high entropy nitride coating on the surface of the pretreated substrate obtained in step S1 by a DC magnetron sputtering method, wherein the DC magnetron sputtering target is a TiZrNbTaM alloy target, and the working gas is a mixture of nitrogen and argon.

The present invention adopts direct current magnetron sputtering technology to prepare the coating at room temperature, which can greatly improve the density and uniformity of the coating, make the coating surface smooth and the structure dense. The method is green, energy-saving and pollution-free. The coating composition, structure and comprehensive performance are controlled by adjusting the distance between the target material and the workpiece, the sputtering current, the bias voltage applied to the substrate and the working gas flow rate.

Preferably, the process parameters of DC magnetron sputtering are: the power of DC magnetron sputtering is 1-3 kW, the test current is 1-5 A, the applied bias voltage is -300--50 V, and the sputtering time is 60-180 min.

The present invention provides a suitable DC magnetron sputtering time to form a suitable coating thickness, and combines suitable current and power, so that TiZrNbTaM atoms obtain sufficient migration energy during the deposition process, and then can diffuse to low surface energy positions for nucleation and growth. Therefore, the obtained coating exhibits a (111) surface preferred orientation, which can effectively improve the hardness of the coating.

Preferably, the flow rate of argon in the working gas is 10-50 sccm, and the flow rate of nitrogen is 10-50 sccm. The present invention controls the nitrogen content and organizational structure in the coating by controlling the flow rate of nitrogen, thereby regulating the comprehensive performance of the coating.

Preferably, the process parameters of plasma glow etching are: etching time of 5-40 min, applied bias of -300--100 V, linear anode ion source current of 0.1-0.4 A, vacuum degree of 2.0×10 ^-5 to 3×10 ^-5 Torr, and argon flow rate of 30-60 sccm.

The present invention etches the substrate before depositing the high entropy nitride coating, which can effectively remove the loose layer and oxide scale on the substrate surface, which is equivalent to atomic-level micro-shot peening, activates the substrate surface, improves the film-substrate bonding strength, and also provides efficient pre-ionization for the subsequent deposition process.

Preferably, in S1, the cleaning conditions of the substrate are as follows: ultrasonic cleaning in a degreasing agent, acetone, ethanol and ultrapure water for 5-30 minutes respectively.

Preferably, the matrix material is selected from any one or more combinations of titanium, titanium alloy and aluminum alloy.

Compared with the prior art, the method for preparing the hard and tough TiZrNbTa-based high entropy nitride coating has the following advantages:

First, compared with the prior art, the present invention adopts DC magnetron sputtering technology, which has a simple process, is easy to evenly deposit large-area complex structural parts, has good controllability, saves materials, is green and environmentally friendly, pollution-free, and has an environmental protection concept of sustainable development. It is suitable for surface protection of automotive machinery parts, molding molds and other products.

Second, the TiZrNbTa-based high entropy nitride coating prepared by the present invention has uniform element distribution, and can form a high-strength and tough coating containing a large amount of high-valence electron concentration elements Ta, W, and Mo.

Third, during the deposition process of the TiZrNbTa-based high-entropy nitride coating prepared by the method of the present invention, atoms obtain sufficient migration energy and can diffuse to low surface energy positions for nucleation and growth. Therefore, the resulting coating exhibits a (111) surface preferential orientation, which can effectively improve the hardness of the coating.

Fourth, since N has a strong binding force with components such as Ti, Zr, Nb, Ta, Mo, Cr, V, and W, the nitrogen content and organizational structure in the coating can be controlled by adjusting the nitrogen flow rate during the deposition process, thereby regulating the comprehensive performance of the coating.

Compared with the prior art, the present invention has the following beneficial effects:

In the present invention, Ti, Zr, Nb, Ta, Mo, Cr, and V are strong nitride-forming elements. The introduction of N element forms a strong covalent bond with the metal component element, which is conducive to the formation of a nitride ceramic phase, so that the coating has high hardness. The present invention also facilitates the formation of a metal-metal bonding bond (Me—Me) through the high valence electron concentration of elements such as Ta, Mo, V, and W, which helps to achieve toughening of the hard coating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a morphology diagram of a TiZrNbTaMoN high entropy nitride coating prepared in Example 1 of the present invention, FIG1(a) is a surface morphology diagram, and FIG1(b) is a cross-sectional morphology diagram;

FIG2 is an XRD spectrum of the TiZrNbTaMoN high entropy nitride coatings prepared in Examples 1, 2, 3, 4 of the present invention and Comparative Examples 1 and 3;

FIG3 is a TEM image of the TiZrNbTaMoN high entropy nitride coating prepared in Example 1 of the present invention;

FIG4 is a graph showing the hardness of the coatings prepared in Example 1 of the present invention and Comparative Example 1 as a function of depth;

FIG5 is a nanoindentation morphology of the coatings prepared in Example 1 of the present invention and Comparative Example 1 with a cubic indenter at 50 mN.

Detailed ways

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.

It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

Without departing from the scope or spirit of the present invention, various improvements and changes 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 present invention description will be apparent to the technician. The present application description and examples are only exemplary. The present invention will be described in detail below in conjunction with the accompanying drawings and specific examples. However, the following examples are limited to explaining the present invention, and the scope of protection of the present invention should cover the entire content of the claims, not just limited to the present examples.

The embodiment of the present invention provides a hard and tough TiZrNbTa-based high entropy nitride coating, the chemical formula of the high entropy nitride coating is Ti _a Zr _b Nb _c Ta _{d Me} N _f , wherein M is Mo or Cr or V or W; a, b, c, d, e, and f are all atomic percentages, 10≤a≤18, 10≤b≤18, 10≤c≤18, 10≤d≤18, 10≤e≤18, 10≤f≤50, and a+b+c+d+e+f＝100, presenting an amorphous/nanocrystalline composite structure or a face-centered cubic nano-polycrystalline structure, having a (111) preferred orientation, and a grain size of 5-100nm. In the present invention, Ti, Zr, Nb, Ta, Mo, Cr, and V are strong nitride-forming elements, and the introduction of N element forms a strong covalent bond with the metal component element, which is conducive to the formation of a nitride ceramic phase, so that the coating has high hardness. At the same time, the high valence electron concentration of elements such as Ta, Mo, V, and W makes it easier to form metal-to-metal bonds, which helps to achieve toughening of the hard coating. In addition, compared with the columnar crystal structure, the amorphous/nanocrystalline composite structure or face-centered cubic nano-polycrystalline structure is conducive to improving the hardness of the coating and inhibiting the initiation and expansion of cracks, thereby giving the high entropy nitride coating excellent comprehensive mechanical properties, that is, both high hardness and high toughness.

In a specific embodiment, the hard and tough TiZrNbTa-based high entropy nitride coating has a thickness of 1 to 5 μm, a hardness of up to 32 GPa, and excellent toughness.

A specific embodiment of the present invention provides a method for preparing a hard and tough TiZrNbTa-based high entropy nitride coating, comprising the following steps:

S1. Provide a substrate, clean and dry the substrate and place it in a vacuum coating chamber;

In a specific embodiment, step S1 ultrasonically cleans the substrate, mechanically polishes any one or more of titanium, titanium alloy, and aluminum alloy substrates, and then ultrasonically cleans them in a degreasing agent for 10 minutes, then ultrasonically cleans them in acetone for 30 minutes, then ultrasonically cleans them in anhydrous ethanol for 15 minutes, and finally ultrasonically cleans them in ultrapure water for 5 minutes, and then takes them out and dries them in a drying oven. Subsequently, the cleaned and dried substrate is loaded into a magnetron sputtering chamber.

S2. Before coating, argon gas is introduced into the vacuum coating chamber through an anode ion source, and the substrate is subjected to plasma glow etching treatment using ionized argon ions;

In a specific embodiment, the vacuum in the vacuum coating chamber of step S2 is evacuated to 2.0×10 ^-5 ~3×10 ^-5 Torr, the chamber temperature is room temperature, the working atmosphere is argon, the flow rate is 30~60sccm, the substrate bias is -300V~-50V, the linear anode ion source current is 0.1A~0.4A, and the etching and cleaning time is 5~40min.

S3. In an inert gas or vacuum atmosphere, a direct current magnetron sputtering device is used to deposit a TiZrNbTa-based high entropy nitride coating on the surface of the substrate using a TiZrNbTaM (M = Mo, Cr, V, W) alloy target as a direct current magnetron sputtering target.

In a specific embodiment, the working atmosphere of step S3 is a mixed gas of argon and nitrogen, the flow rate of argon is 10-50 sccm, and the flow rate of nitrogen is 10-50 sccm. The sputtering target is a TiZrNbTaM (M=Mo, Cr, V, W) alloy target, and its specific component molar ratio is Ti:Zr:Nb:Ta:M=1:1:1:1:1. The chamber temperature is room temperature, the deposition bias is -300V to -50V, the sputtering power is 1-3kW, the sputtering current is 1-5A, and the sputtering time is 60-180min.

The composition, microstructure and coating thickness of the TiZrNbTa-based high-entropy nitride coating prepared by the above method are adjustable. Specifically, the composition and microstructure of the coating can be controlled by controlling the flow rates of nitrogen and argon to obtain high-entropy nitride coatings with different compositions and organizational structures. The preferred coating composition is a Nb content of 10 to 18 at.%, a Ta content of 10 to 18 at.%, a Ti content of 10 to 18 at.%, a Zr content of 10 to 18 at.%, a M (M = Mo, Cr, V, W) content of 10 to 18 at.%, and a N content of preferably 10% to 50 at.%.

The coating prepared by the above method has good compactness, uniformity and strong film-base bonding. The TiZrNbTa-based high entropy nitride coating is an amorphous/nanocrystalline composite structure or a face-centered cubic nano-polycrystalline structure. Compared with the columnar crystal structure, it improves the hardness of the coating while inhibiting the initiation and expansion of cracks, so that the coating has both high hardness and high toughness and excellent wear resistance. In addition, the above preparation method is simple in process, easy to uniformly deposit large-area complex structural parts, good in controllability, high in efficiency, green and environmentally friendly, pollution-free, and conducive to industrial production. It has broad application prospects in the fields of automotive machinery parts, molding molds and other products.

The technical effects of the present invention are described below in conjunction with specific embodiments.

Example 1

In this embodiment, the substrate is a titanium alloy with a grade of Ti6Al4V, and the TiZrNbTaMoN high entropy nitride coating on the substrate surface is prepared as follows:

S1. The titanium alloy substrate (Ti6Al4V) is polished, and then ultrasonically cleaned in a degreasing agent, acetone, ethanol and ultrapure water for 5 to 30 minutes respectively, and then dried and placed in a vacuum chamber of a DC magnetron sputtering device.

S2. Before coating, the vacuum in the vacuum chamber is below 3.0×10 ^-5 Torr, 60 sccm of argon gas is introduced into the vacuum coating chamber through the anode ion source, the chamber temperature is room temperature, the linear ion source current is set to 0.2A, the substrate bias is -150V, and the substrate is etched with ionized argon ions for 30 minutes.

S3. In an argon protective atmosphere of 50 sccm, the magnetron source is a TiZrNbTaMo alloy target (molar ratio of Ti:Zr:Nb:Ta:Mo=1:1:1:1:1), the target power is 2.0 kW, the current is 5 A, the substrate bias is -150 V, 10 sccm of nitrogen is introduced, and the deposition is carried out for 60 minutes. During the deposition of the coating, the substrate rotates evenly in the cavity to obtain a TiZrNbTaMoN high entropy nitride coating.

After testing, the total thickness of the coating in this embodiment is 2μm, and the contents of each component element are respectively 16at.% Nb, 17at.%, 17at.%, 17at.%, 16at.% Ta, 17at.%, 16at.% Zr and 17at.%. Figure 1 is a surface area cross-sectional morphology of the TiZrNbTaMoN high entropy nitride coating prepared in this embodiment. From the surface morphology of Figure 1 (a), it can be seen that the prepared coating has a uniform and dense surface. From the cross-sectional view of the coating in 1 (b), it can be seen that the thickness of the coating prepared in this embodiment is about 2μm, the coating structure is complete, and it can be clearly observed that the coating is well combined with the substrate without obvious peeling, cracking, holes and other defects. Figure 2 is an XRD spectrum of the prepared coating. It can be seen from the figure that the coating prepared in Example 1 is an amorphous/nanocrystalline composite structure. FIG3 is a TEM image of the coating prepared in this embodiment, in which the amorphous halo and the diffraction ring of the FCC nanocrystal can be found, further proving that the coating is composed of an amorphous/nanocrystalline composite structure, which is consistent with the XRD results. FIG4 is a nanoindenter with a Berkovich diamond indenter for hardness testing of the coating prepared in this embodiment, the test mode is the continuous stiffness method (CSM), the indentation depth is selected as 1000nm, and the hardness value is selected as the value corresponding to the hardness curve platform. The depth value of 150-200nm is about 1/10 of the coating thickness. The test results show that the hardness (H) of the TiZrNbTaMoN high entropy nitride coating prepared in Example 1 reaches 32Gpa, indicating that the coating has high hardness. Combined with the residual morphology of the nanoindentation of the cubic indenter under a force of 50mN (see FIG5). As can be seen from (a) in FIG5, no annular cracks appear around the indentation, and only short radial cracks (~3μm) appear, indicating that the coating has excellent toughness.

Example 2

In this embodiment, the substrate is pure titanium with a grade of TA2, and the TiZrNbTaMoN high entropy nitride coating on the surface of the substrate is prepared as follows:

S1. The pure titanium substrate is polished, and then ultrasonically cleaned in a degreasing agent, acetone, ethanol and ultrapure water for 5 to 30 minutes respectively, and then dried and placed in a vacuum chamber of a DC magnetron sputtering device.

S2. Before coating, the vacuum in the vacuum chamber is below 3.0×10 ^-5 Torr, 43 sccm of argon gas is introduced into the vacuum coating chamber through the anode ion source, the chamber temperature is room temperature, the linear ion source current is set to 0.1A, the substrate bias is -300V, and the substrate is etched with ionized argon ions for 40 minutes.

S3. In a 40sccm argon protective atmosphere, the magnetron source is a TiZrNbTaMo alloy target (molar ratio of Ti:Zr:Nb:Ta:Mo=1:1:1:1:1), the target power is 1.0kW, the current is 1A, the substrate bias is -300V, 20sccm nitrogen is introduced, and the deposition is carried out for 150min. During the deposition of the coating, the substrate rotates evenly in the cavity to obtain a TiZrNbTaMoN high-entropy nitride coating.

After testing, the contents of the components of the coating prepared in this embodiment are respectively 13 at.% Nb, 14 at.% Mo, 13 at.%, 13 at.% Ta, 13 at.% Ti, 12 at.% Zr and 35 at.%. The total thickness of the coating in this embodiment is 5 μm. As shown in FIG. 2 , the coating prepared in this embodiment is a single-phase FCC structure.

The coating prepared in this embodiment is tested for hardness by a nanoindenter with a Berkovich diamond indenter. The test mode is the continuous stiffness method (CSM), the indentation depth is selected as 1000nm, and the hardness value is selected as the value corresponding to the hardness curve platform. The depth value of about 400-500nm is about 1/10 of the coating thickness. The test results show that the hardness (H) of the TiZrNbTaMoN high entropy nitride coating prepared in Example 2 reaches 17Gpa, indicating that the coating has high hardness. Combined with the residual morphology of the nanoindentation of the cubic indenter under a force of 50mN, there is no annular crack around the indentation, and there are only short radial cracks (4.3μm), indicating that the coating has excellent toughness.

Example 3

In this embodiment, the substrate is an aluminum alloy with a grade of 6061, and the TiZrNbTaMoN high entropy nitride coating on the surface of the substrate is prepared as follows:

S1. The aluminum alloy substrate is polished, and then ultrasonically cleaned in a degreasing agent, acetone, ethanol and ultrapure water for 5 to 30 minutes respectively, and then dried and placed in a vacuum chamber of a DC magnetron sputtering device.

S2. Before coating, the vacuum in the vacuum chamber is below 3.0×10 ^-5 Torr, 30 sccm of argon gas is introduced into the vacuum coating chamber through the anode ion source, the chamber temperature is room temperature, the linear ion source current is set to 0.4A, the substrate bias is -100V, and the substrate is etched with ionized argon ions for 10 minutes.

S3. In a 30sccm argon protective atmosphere, the magnetron source is a TiZrNbTaMo alloy target (molar ratio of Ti:Zr:Nb:Ta:Mo=1:1:1:1:1), the target power is 2.0kW, the current is 3.8A, the substrate bias is -50V, 30sccm of nitrogen is introduced, and the deposition is 70min. During the deposition of the coating, the substrate rotates evenly in the cavity to obtain a TiZrNbTaMoN high-entropy nitride coating. The total thickness of the coating in this embodiment is 1μm.

The nanoindenter with a Berkovich diamond indenter performs a hardness test on the coating obtained in this embodiment. The test mode is the continuous stiffness method (CSM), the indentation depth is selected as 500nm, and the hardness value is selected as the value corresponding to the hardness curve platform. The depth value of about 50-100nm is about 1/10 of the coating thickness. The test results show that the hardness (H) of the TiZrNbTaMoN high entropy nitride coating obtained in Example 3 reaches 20GPa, indicating that the coating has high hardness. Combined with the residual morphology of the nanoindentation of the cubic indenter under a force of 50mN, there is no annular crack around the indentation, and there are only short radial cracks (4.5μm), indicating that the coating has excellent toughness.

Example 4

In this embodiment, the substrate is a titanium alloy with a grade of Ti6Al4V, and the TiZrNbTaMoN high entropy nitride coating on the substrate surface is prepared as follows:

S1. The titanium alloy substrate (Ti6Al4V) is polished, and then ultrasonically cleaned in a degreasing agent, acetone, ethanol and ultrapure water for 5 to 30 minutes respectively, and then dried and placed in a vacuum chamber of a DC magnetron sputtering device.

S2. Before coating, the vacuum in the vacuum chamber is below 3.0×10 ^-5 Torr, 60 sccm of argon gas is introduced into the vacuum coating chamber through the anode ion source, the chamber temperature is room temperature, the linear ion source current is set to 0.2A, the substrate bias voltage is -200V, and the substrate is etched with ionized argon ions for 5 minutes.

S3. In an argon protective atmosphere of 10 sccm, the magnetron source is a TiZrNbTaMo alloy target (molar ratio of Ti:Zr:Nb:Ta:Mo=1:1:1:1:1), the target power is 3.0 kW, the current is 3.8 A, the substrate bias is -200 V, 50 sccm of nitrogen is introduced, and the deposition is performed for 180 minutes. During the deposition of the coating, the substrate rotates evenly in the cavity to obtain a TiZrNbTaMoN high-entropy nitride coating.

The contents of the constituent elements of the coating prepared in this embodiment are 10 at.% Nb, 10 at.% Mo, 10 at.% Ta, 10 at.% Ti, 10 at.% Zr, and 50 at.%. The total thickness of the coating in this embodiment is 3 μm. As shown in FIG. 2 , the coating prepared in this embodiment has a single-phase FCC structure.

The nanoindenter with a Berkovich diamond indenter performs a hardness test on the coating obtained in this embodiment. The test mode is the continuous stiffness method (CSM), the indentation depth is selected as 1000nm, and the hardness value is selected as the value corresponding to the hardness curve platform. The depth value of about 200-300nm is about 1/10 of the coating thickness. The test results show that the hardness (H) of the TiZrNbTaMoN high entropy nitride coating obtained in Example 4 reaches 22Gpa, indicating that the coating has high hardness. Combined with the residual morphology of the nanoindentation of the cubic indenter under a force of 50mN, there is no annular crack around the indentation, and there are only short radial cracks (3.9μm), indicating that the coating has excellent toughness.

Example 5

In this embodiment, the substrate is a titanium alloy with a grade of Ti6Al4V, and the TiZrNbTaCrN high entropy nitride coating on the substrate surface is prepared as follows:

S1. The titanium alloy substrate (Ti6Al4V) is polished, and then ultrasonically cleaned in a degreasing agent, acetone, ethanol and ultrapure water for 5 to 30 minutes respectively, and then dried and placed in a vacuum chamber of a DC magnetron sputtering device.

S2. Before coating, the vacuum in the vacuum chamber is below 3.0×10 ^-5 Torr, 60 sccm of argon is introduced into the vacuum coating chamber through the anode ion source, the chamber temperature is room temperature, the linear ion source current is set to 0.2A, the substrate bias voltage is -200V, and the substrate is etched with ionized argon ions for 30 minutes.

S3. In a 30sccm argon protective atmosphere, the magnetron source is a TiZrNbTaCr alloy target (molar ratio of Ti:Zr:Nb:Ta:Cr=1:1:1:1:1), the target power is 2.0kW, the current is 3.8A, the substrate bias is -100V, 30sccm nitrogen is introduced, and the deposition is carried out for 150min. During the deposition of the coating, the substrate rotates evenly in the cavity to obtain a TiZrNbTaCrN high-entropy nitride coating.

The contents of the constituent elements of the coating prepared in this embodiment are 11 at.% Nb, 14 at.% Cr, 11 at.% Ta, 13 at.% Ti, 11 at.% Zr and 40 at.% N. The total thickness of the coating in this embodiment is 2.5 μm. The coating prepared in this embodiment has a single-phase FCC structure.

The nanoindenter with a Berkovich diamond indenter performs a hardness test on the coating obtained in this embodiment. The test mode is the continuous stiffness method (CSM), the indentation depth is selected as 1000nm, and the hardness value is selected as the value corresponding to the hardness curve platform. The depth value of about 150-200nm is about 1/10 of the coating thickness. The test results show that the hardness (H) of the TiZrNbTaMoN high entropy nitride coating obtained in Example 5 reaches 20GPa, indicating that the coating has high hardness. Combined with the residual morphology of the nanoindentation of the cubic indenter under a force of 50mN, there is no annular crack around the indentation, and there are only short radial cracks (4.4μm), indicating that the coating has excellent toughness.

Comparative Example 1

This comparative example is a comparative example of Example 1, the substrate is a titanium alloy with a grade of Ti6Al4V, and the preparation method of the TiZrNbTaMoN high entropy nitride coating on the surface of the substrate is as follows:

S1. The titanium alloy substrate (Ti6Al4V) is polished, and then ultrasonically cleaned in a degreasing agent, acetone, ethanol and ultrapure water for 5 to 30 minutes respectively, and then dried and placed in a vacuum chamber of a DC magnetron sputtering device.

S2. Before coating, the vacuum in the vacuum chamber is below 3.0×10 ^-5 Torr, 60 sccm of argon gas is introduced into the vacuum coating chamber through the anode ion source, the chamber temperature is room temperature, the linear ion source current is set to 0.2A, the substrate bias is -150V, and the substrate is etched with ionized argon ions for 30 minutes.

S3. In an argon protective atmosphere of 60 sccm, the magnetron source is a TiZrNbTaMo alloy target (molar ratio of Ti:Zr:Nb:Ta:Mo = 1:1:1:1:1), the target power is 2.0 kW, the current is 5 A, the deposition time is 60 min, the substrate bias is -150 V, and the deposition time is 60 min. During the deposition of the coating, the substrate rotates evenly in the cavity to obtain a TiZrNbTaMo high entropy coating. The thickness of the coating in this comparative example is 3 μm.

After testing, the contents of each component element in the coating prepared in this comparative example are respectively 20 at.% Nb, 20 at.%, 19 at.%, 21 at.% Ti, and 20 at.%. Referring to Figures 2 and 4, it can be seen that the coating prepared in this comparative example has a BCC structure, which is different from the FCC structure in Example 1, and the hardness of the coating is 8.5 GPa. According to Figure 5 (b), it can be seen that the radial cracks around the nanoindentation residual indentation of the cubic indenter under a force of 50 mN are relatively long (~5 μm), indicating that the toughness of the coating prepared in this comparative example is poor, not as good as the TiZrNbTaMoN high entropy nitride coating obtained in Example 1.

Referring to Figures 1 to 5, it can be seen from the results of Example 1 and this comparative example that the nitrogen flow rate has an effect on the mechanical properties of the coating. When the nitrogen flow rate introduced in the preparation method is not within the scope of the invention patent, the hardness of the obtained coating is greatly reduced.

Comparative Example 2

In this comparative example, the substrate is pure titanium with a grade of TA2, and the preparation method of the TiZrNbTaMoN high entropy nitride coating on the surface of the substrate is as follows:

S1. The titanium alloy substrate (Ti6Al4V) is polished, and then ultrasonically cleaned in a degreasing agent, acetone, ethanol and ultrapure water for 5 to 30 minutes respectively, and then dried and placed in a vacuum chamber of a DC magnetron sputtering device.

S2. Before coating, the vacuum in the vacuum chamber is below 3.0×10 ^-5 Torr, 43 sccm of argon gas is introduced into the vacuum coating chamber through the anode ion source, the chamber temperature is room temperature, the linear ion source current is set to 0.1A, the substrate bias is -300V, and the substrate is etched with ionized argon ions for 40 minutes.

S3. In an argon protective atmosphere of 55 sccm, the magnetron source is a TiZrNbTaMo alloy target (molar ratio of Ti:Zr:Nb:Ta:Mo = 1:1:1:1:1), the target power is 1.0 kW, the current is 1 A, 5 sccm of nitrogen is introduced, and the deposition is 60 minutes. During the deposition of the coating, the substrate rotates evenly in the cavity to obtain a TiZrNbTaMoN high entropy nitride coating. The total thickness of the coating in this comparative example is 2 μm.

After testing, the contents of each component element are respectively 18 at.% Nb, 18 at.% Mo, 19 at.%, 19 at.% Ta, 19 at.% Ti, 19 at.% Zr and 7 at.%. The coating has a BCC structure and the hardness of the coating is 10 GPa. It can be seen from the results of Example 2 and this comparative example that the coating component ratio has an effect on the mechanical properties of the coating. When the content of each component element is not within the range described in the present invention, the hardness and toughness of the obtained coating are both reduced.

In summary, the present invention reasonably adjusts the nitrogen flow rate, controls the composition of the coating, regulates the amorphous/nanocrystalline composite structure or face-centered cubic nano-polycrystalline structure of the coating, and reasonably adjusts the preparation process, so that the obtained high entropy coating has excellent comprehensive mechanical properties of strength and toughness and high bonding strength with the membrane substrate.

Comparative Example 3

In this comparative example, the substrate is a titanium alloy with a grade of Ti6Al4V, and the TiZrNbTaMoN high entropy nitride coating on the substrate surface is prepared as follows:

S1. The titanium alloy substrate (Ti6Al4V) is polished, and then ultrasonically cleaned in a degreasing agent, acetone, ethanol and ultrapure water for 5 to 30 minutes respectively, and then dried and placed in a vacuum chamber of a DC magnetron sputtering device.

S2. Before coating, the vacuum in the vacuum chamber is below 3.0×10 ^-5 Torr, 60 sccm of argon gas is introduced into the vacuum coating chamber through the anode ion source, the chamber temperature is room temperature, the linear ion source current is set to 0.2A, the substrate bias is -150V, and the substrate is etched with ionized argon ions for 30 minutes.

S3. In an argon protective atmosphere of 30 sccm, the magnetron source is a TiZrNbTaMo alloy target (molar ratio of Ti:Zr:Nb:Ta:Mo=1:1:1:1:1), the target power is 2.0 kW, the current is 5 A, the substrate bias is -150 V, 10 sccm of nitrogen is introduced, and the deposition is 200 minutes. During the deposition process of the coating, the substrate rotates evenly in the cavity to obtain a TiZrNbTaMoN high entropy nitride coating.

After testing, the total thickness of the coating in this comparative example is 6 μm, which is different from the coating thickness in Examples 1-5. According to the XRD spectrum of Figure 2, it can be seen that the coating obtained in this comparative example has a (200) orientation, which is different from the (111) preferred orientation of the coating obtained in the example. When the deposition time and thickness of the coating are not within the scope of the invention patent, the texture of the obtained coating is different.

Although the disclosure is disclosed as above, the protection scope of the 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 disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims (10)

1. A TiZrNbTa-based high entropy nitride coating, characterized in that the chemical formula of the TiZrNbTa-based high entropy nitride coating is Ti _a Zr _b Nb _c Ta _{d Me} N _f , wherein M is Mo or Cr or V or W, and the atomic percentage of each element is 10≤a≤18, 10≤b≤18, 10≤c≤18, 10≤d≤18, 10≤e≤18, 10≤f≤50, and a+b+c+d+e+f=100. 2. The TiZrNbTa-based high-entropy nitride coating according to claim 1 is characterized in that the microstructure of the TiZrNbTa-based high-entropy nitride coating is a face-centered cubic structure with a (111) preferred orientation. 3. The TiZrNbTa-based high entropy nitride coating according to claim 1, wherein the atomic percentage of the N element is 40≤f≤50. 4 . The TiZrNbTa-based high entropy nitride coating according to claim 3 , wherein the atomic percentage of the N element is 10≤f≤25. 5 . The TiZrNbTa-based high entropy nitride coating according to claim 1 , wherein the high entropy nitride coating is nanocrystalline or amorphous nanocrystalline, and a grain size is 5-100 nm. 6 . The TiZrNbTa-based high entropy nitride coating according to claim 1 , wherein the thickness of the TiZrNbTa-based high entropy nitride coating is 1-5 μm. 7. A method for preparing a TiZrNbTa-based high entropy nitride coating according to any one of claims 1 to 6, characterized in that it comprises: S1, cleaning and drying the substrate, and performing plasma glow etching treatment on the dried substrate using ionized argon gas to obtain a pretreated substrate; S2. Depositing the TiZrNbTa-based high entropy nitride coating on the surface of the pretreated substrate obtained in step S1 by a DC magnetron sputtering method, wherein the DC magnetron sputtering target is a TiZrNbTaM alloy target, and the working gas is a mixture of nitrogen and argon. 8. The method for preparing a TiZrNbTa-based high entropy nitride coating according to claim 7, characterized in that the process parameters of DC magnetron sputtering are: the power of DC magnetron sputtering is 1-3 kW, the test current is 1-5 A, and the sputtering time is 60-180 min. 9 . The method for preparing a TiZrNbTa-based high entropy nitride coating according to claim 7 , wherein the flow rate of argon gas in the working gas is 10-50 sccm, and the flow rate of nitrogen gas is 10-50 sccm. 10. The method for preparing a TiZrNbTa-based high entropy nitride coating according to claim 7, characterized in that the process parameters of plasma glow etching are: etching time is 5-40 min, applied bias voltage is -300--100 V, linear anode ion source current is 0.1-0.4 A, vacuum degree is 2.0× ^10-5-3 × ^10-5 Torr, and argon flow rate is 30-60 sccm.