阅读说明：本技术 熵稳定陶瓷薄膜涂层，其制备方法以及涂覆有该涂层的元件 (Entropy-stable ceramic thin film coating, method for the production thereof and element coated with such a coating ) 是由 卞海东 赫全锋 李泽彪 吕坚 杨勇 李扬扬 于 2020-04-23 设计创作，主要内容包括：本发明公开了一种制备熵稳定陶瓷薄膜涂层的方法,包括制备由多种金属元素形成的第一层,以及使第一层与阴离子反应从而将第一层的至少一部分转变成第二层。本发明还公开了一种熵稳定陶瓷薄膜涂层以及涂覆有熵稳定陶瓷薄膜涂层的元件。(A method of producing an entropy-stable ceramic thin film coating includes producing a first layer formed from a plurality of metal elements, and reacting the first layer with anions to convert at least a portion of the first layer into a second layer. The invention also discloses an entropy-stable ceramic thin film coating and an element coated with the entropy-stable ceramic thin film coating.)

1. A method of preparing an entropy stable ceramic thin film coating comprising the steps of:

a) preparing a first layer formed of a raw material having a plurality of metal elements; and

b) reacting the first layer with an anion, thereby converting at least a portion of the first layer to a second layer.

2. The method of claim 1, wherein the first layer is arranged to react with anions in a top-down manner.

3. The method of claim 1, wherein the feedstock is provided in approximately equal atomic ratios.

4. The method of claim 1, wherein the raw material is selected from the group consisting of titanium, aluminum, vanadium, iron, cobalt, nickel, chromium, and niobium.

5. The method of claim 1, wherein the second layer is tightly bonded to the first layer.

6. The method of claim 5, wherein step b) further comprises the step of forming a mesoporous structure between the first layer and the second layer.

7. The method of claim 6, wherein the physical properties of the film are related to the morphology of the mesoporous structure.

8. The method of claim 7, wherein the mesoporous structure has a pore size of 10 to 50 nm.

9. The method of claim 1, wherein the first layer comprises an entropy-stabilized alloy.

10. The method of claim 9, wherein the entropy-stable alloy is selected from the group consisting of TiAlV, TiAlVCr, FeCoNi, and TiAlVNbCr.

11. The method of claim 1, wherein step b) further comprises the step of anodizing the first layer with the anions to form the second layer.

12. The method of claim 11, wherein the anions are incorporated into the crystal lattice of the first layer under an anodized electric field to form the second layer.

13. The method of claim 1, wherein the anion comprises an oxyanion.

14. The method of claim 1, wherein the second layer comprises an oxide.

15. The method of claim 11, wherein the physical properties of the thin film are controlled by at least one of an anodic oxidation potential, a type of electrolyte, a concentration of electrolyte, and a duration of anodic oxidation.

16. The method of claim 15, wherein the anodic oxidation potential is 10 to 100V.

17. The method of claim 15, wherein the electrolyte comprises an acid solution.

18. An entropy-stable ceramic thin film coating prepared by the method of claim 1.

19. The entropy stabilized ceramic thin film coating of claim 18, wherein the hardness is between 9 and 14 GPa.

20. The entropy-stabilized ceramic thin film coating of claim 19, wherein the reduction modulus is between 140 and 190 GPa.

21. An element coated with an entropy-stabilized ceramic thin-film coating according to claim 18.

Technical Field

The invention relates to an entropy-stable ceramic thin-film coating, a method for the production thereof and an element coated with the coating.

Background

Entropy stable ceramics have superior physical and mechanical properties. Current manufacturing methods are limited to additive processes such as sputtering, laser cladding, atomized spray pyrolysis or high temperature sintering processes. However, this method of manufacture has several insurmountable limitations. For example, these entropy-stabilized ceramic techniques typically require expensive equipment such as vacuum, shielding gas, or complex control systems. In addition, these techniques only provide small area manufacturing with low uniformity, small scale production, and in fact the manufacturing process is very cumbersome. Thus, entropy-stable ceramics are only suitable for several entropy-stable alloys and are not suitable for commercialization.

Disclosure of Invention

In one aspect of the invention, there is provided a method of preparing an entropy-stable ceramic thin film coating, comprising the steps of:

a) preparing a first layer formed of a raw material having a plurality of metal elements; and

b) the first layer is reacted with an anion, thereby converting at least a portion of the first layer to a second layer.

In one embodiment, the first layer is arranged to react with the anion in a top-down manner.

In one embodiment, the starting materials are provided in approximately equal atomic ratios.

In one embodiment, the raw material is selected from titanium, aluminum, vanadium, iron, cobalt, nickel, chromium, and niobium.

In one embodiment, the second layer is tightly bonded to the first layer.

In one embodiment, step b) further comprises the step of forming a mesoporous structure between the first layer and the second layer.

In one embodiment, the physical properties of the film are related to the morphology of the mesoporous structure.

In one embodiment, the pore size of the mesoporous structure is from 10 to 50 nm.

In one embodiment, the first layer comprises an entropy stable alloy.

In one embodiment, the entropy-stabilizing alloy is selected from the group consisting of TiAlV, TiAlVCr, FeCoNi, and TiAlVNbCr.

In one embodiment, step b) further comprises the step of anodizing the first layer with anions to form the second layer.

In one embodiment, anions are incorporated into the crystal lattice of the first layer under the electric field of anodization to form a second layer.

In one embodiment, the anion comprises an oxyanion.

In one embodiment, the second layer comprises an oxide.

In one embodiment, the physical properties of the thin film are controlled by at least one of an anodic oxidation potential, a type of electrolyte, a concentration of the electrolyte, and a duration of the anodic oxidation.

In one embodiment, the anodization potential is 10 to 100V.

In one embodiment, the electrolyte comprises an acid solution.

In another aspect of the invention, entropy stable ceramic thin film coatings prepared according to the methods described herein are provided.

In one embodiment, the hardness is between 9 and 14 GPa.

In one embodiment, the reduced modulus is between 140 and 190 GPa.

In yet another aspect of the invention, there is provided an element coated with an entropy-stable ceramic thin film coating as described herein.

Drawings

The invention will be further described with reference to the accompanying drawings which illustrate possible arrangements of the invention. Other arrangements of the invention are possible and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.

FIG. 1 illustrates an entropy-stable alloy, anions, and an entropy-stable ceramic used in a reaction to produce an entropy-stable ceramic in an exemplary embodiment of the invention;

FIG. 2a is a set of grayscale photomicrographs depicting the applied anodization potential of 10 to 100V;

FIG. 2b is a top view of a Scanning Electron Microscope (SEM) image of an entropy-stabilized ceramic produced by the present method at an anodic oxidation potential of 10V for 2 hours;

FIG. 2c is a top view of an SEM image of an entropy-stabilized ceramic produced by the present method at an anodization potential of 20V for 2 hours;

FIG. 2d is a top view of an SEM image of an entropy-stabilized ceramic produced by the present method at an anodization potential of 30V for 2 hours;

FIG. 2e is a top view of an SEM image of an entropy-stabilized ceramic produced by the present method at an anodization potential of 40V for 2 hours;

FIG. 2f is a top view of an SEM image of an entropy-stabilized ceramic produced by the present method at an anodization potential of 50V for 2 hours;

FIG. 2g is a top view of an SEM image of an entropy-stabilized ceramic produced by the present method at an anodization potential of 60V for 2 hours;

FIG. 2h is a top view of an SEM image of an entropy-stabilized ceramic produced by the present method at an anodization potential of 70V for 2 hours;

FIG. 2i is a top view of an SEM image of an entropy-stabilized ceramic produced by the present method at an anodization potential of 80V for 2 hours;

FIG. 2j is a top view of an SEM image of an entropy-stabilized ceramic produced by the present method at an anodization potential of 90V for 2 hours;

FIG. 2k is a top view of an SEM image of an entropy-stabilized ceramic produced by the present method at an anodization potential of 100V for 2 hours;

fig. 3 provides a plurality of images associated with the present method, wherein: image a is an image of the entropy-stabilized ceramic produced by the method; image b is a High Resolution Transmission Electron Microscope (HRTEM) image of the entropy stabilized ceramic of image a and the corresponding selected region electron diffraction (SAED) results; FIG. c is an energy chromatography (EDS) map image of the entropy stabilized ceramic of FIG. a; image d shows only the aluminum content of the entropy-stabilized ceramic in the EDS-mapped image of image c; image e shows only the oxygen content of the entropy-stabilized ceramic in the EDS-mapped image of image c; image f shows only the titanium content of the entropy-stabilized ceramic in the EDS-mapped image of image c; graph g shows only the vanadium content of the entropy-stable ceramic in the EDS map of figure c;

FIG. 4 is TiAlVO prepared at 100V anodic oxidation potential for 2 hours_xAn X-ray photoelectron spectroscopy (XPS) depth profile of an entropy-stabilized oxide (ESO);

FIG. 5a is a graph showing TiAlVO obtained at different anodic oxidation potentials in the range of 10-100V_xHardness profile of ESO; and

FIG. 5b is a graph showing TiAlVO obtained at different anodic oxidation potentials in the range of 10-100V_xGraph of the reduced modulus of ESO.

Detailed Description

The inventor designs the entropy-stable ceramic through own research, experiments and experiments, has excellent mechanical and physical properties, and invents a practical method for preparing the entropy-stable ceramic, which can be used for industrial application.

The inventors have found that the existing major entropy-stable ceramic elements are usually manufactured by combining or sintering several metal salts or ceramics in a "bottom-up" process, often requiring expensive equipment, such as vacuum devices, protective gases or complex control systems, long high temperature treatments and/or complex synthesis processes, to obtain entropy-stable ceramics, which inevitably increases the manufacturing costs of the entropy-stable ceramics and limits their practical applications.

In the present invention, the inventors have devised a completely novel, rapid, yet simple and economical method that consumes less energy to produce entropy-stable ceramic membranes.

Referring first to FIG. 1, there is provided a method of making an entropy stable ceramic thin film coating 100 comprising the steps of: preparing a first layer 102 formed of a raw material having a plurality of metal elements; and reacting the first layer 102 with an anion 120, thereby converting at least a portion of the first layer 102 into the second layer 104.

Turning now to the detailed structure of thin film coating 100, thin film coating 100 preferably comprises at least two layers, a first layer 102 serving as a substrate, a second layer 104 formed on top of first layer 102 as a coating, and a mesoporous structure 106 sandwiched between first layer 102 and second layer 104.

The first layer 102 may be formed of an alloy material (e.g., various entropically stable alloys such as TiAlV, TiAlVCr, FeCoNi, and TiAlVNbCr) made from a raw material selected from a plurality of metals (e.g., titanium, aluminum, vanadium, iron, cobalt, nickel, chromium, and niobium) having approximately equal atomic ratios. Such entropy-stabilized alloys are defined as solid solution alloys containing three or more major elements that are the same or nearly the same in atomic percent. These alloys have a very high entropy of mixing and are thermodynamically very stable. These entropy stable alloys have unique physical and mechanical properties compared to conventional alloys.

To fabricate the second layer 104, the upper surface of the first layer 102 is electrochemically reacted to partially remove metal atoms from the first layer 102 in a "top-down" manner, i.e., from top to bottom. The second layer 104 will be formed and intimately bonded to the underlying first layer 102.

For example, the first layer 102 can be anodized with an anion 120, such as an oxygen anion or a sulfur anion. By anodizing the entropy stable alloy forming the first layer 102 with oxygen or sulfur anions 120, the anions 120 may be incorporated into the crystal lattice of the first layer 102 under an electric field. In turn, the surface of the first layer 102 will form a second layer 104 of oxide or sulfide, i.e., a stable amorphous near equimolar oxide or sulfide, such as TiAlVO_xAn entropy-stable oxide. The oxide or sulfide layer 104 will be coupled to the first layer 102 by a bond therebetween.

To form such a mesoporous structure 106, the first layer 102 (e.g., an entropy-stable alloy) may be anodized within a bipolar battery that typically includes a power source, a cathode, an anode, and an electrolyte. In one exemplary arrangement, the anode may be the entropy stable alloy 102, the cathode may be platinum, and the electrolyte may be an acid solution, such as oxalic acid. The anode 102 may be treated in the electrolyte for a short period of time (e.g., from several minutes to several hours).

During anodization, the mesoporous structure 106 may grow directly on the metal surface of the first layer 102, and thus the second layer 104 will be tightly bonded to the first layer 102. Preferably, the mesoporous structure 106 comprises a plurality of pores 108, each pore 108 having a diameter in the range of 10 to 50 nm.

Alternatively, by adjusting anodization parameters, such as anodization potential, electrolyte concentration, etc., various mesoporous entropy-stable ceramic membranes 100 having different pore sizes, ligament widths, porosities, tunable colors, and mechanical properties can be obtained. For example, as shown in fig. 2a, the anodization may be performed in the range of 10 to 100V for a period of several minutes to several hours, preferably 2 hours at a time. Fig. 2b to 2k depict ten entropy-stable ceramics 104 with different color tones, which were produced at ten different anodization potentials, respectively.

Advantageously, many possible entropy-stable ceramics 104 may be formed by processing different entropy-stable alloys 102 directly in various electrolytes. Thus, for example, the present invention is well suited for the rapid development of new entropy-stable ceramics 100 by using different anodization parameters and selecting different chemicals, such as anodes or electrolytes, for anodization.

In one exemplary embodiment, TiAlVO is fabricated by anodization of the present invention_xProvided is a system. Referring to images a to g of fig. 3, the amorphous character of the prepared entropy stabilized ceramic 104 is revealed by HRTEM and SAED characterization. Elemental mapping results, i.e. TiAlVO_xAnd the electronic images of each of the constituent elements Ti, V, Al, and O, shown in the same scale in each of the corresponding EDS map images, indicate a uniform distribution of the constituent elements.

Referring also to FIG. 4, the same TiAlVO was aligned by X-ray photoelectron spectroscopy (XPS)_xThe system carries out deep analysis and draws the relationship between the element content of each element O, Ti, V and Al and the depth of the film. It is particularly noted that from 0nm to 250nm, the three metal component elements Ti, V, Al have approximately the same element content and the element content of O is substantially the sameGreater than these metal components. This indicates that the metal elements of V, Ti and Al are distributed nearly equimolar on the upper surface of the thin film 100.

Advantageously, the entropy stabilizing ceramic film 104 is tightly bonded to the entropy stabilizing alloy substrate 102. Once the film 104 is bonded to the underlying substrate 102, its mechanical properties and iridescent characteristics, such as the visual color of the film 100, are significantly increased. Such properties enable many potential applications as protective or decorative coatings or coating materials for, for example, cell phone and automobile housings.

Referring to fig. 5a to 5b, the nanoindentation test shows that the hardness (H) of the mesoporous film 100 is in the range of 9 to 14GPa, and the reduced modulus of refraction (Er) is in the range of 140 to 190 GPa. The variable mechanical properties of the entropy-stabilized ceramic membrane 104 depend to a large extent on its morphology, such as pore size, ligament thickness and porosity of the obtained mesoporous entropy-stabilized ceramic. Overall, the prepared entropy-stable ceramic films 100 exhibit excellent mechanical properties; they are inherently stiff and inflexible.

Advantageously, the present invention provides an economical and efficient anodizing process for producing entropy stable ceramic coatings. It aims to reduce the manufacturing cost of the current entropy-stable ceramics and realize various novel entropy-stable oxides. By adjusting the anodic oxidation parameters, the entropy-stable ceramic film can be directly formed on the surface of the entropy-stable alloy.

Advantageously, since the present invention relates to a solution-based approach, it will be highly compatible with various industrial applications. The physical properties of the entropy-stabilized ceramic film 100 obtained by such a manufacturing method are advantageous, and thus practical applications thereof can be realized. For example, the entropy-stabilized ceramic films 100 produced by the present invention are of high quality, have significant mechanical, corrosion-resistant, and physical properties, and interesting optical characteristics, and can be simply produced in film colors over a wide range of the visible spectrum.

Advantageously, the entropy-stable ceramic 104 grown on the substrate 102 from the entropy-stable alloy also exhibits excellent chemical stability. Thus, the protective and decorative layers formed by the present invention are suitable for use in applications under extreme environmental conditions.

From a microscopic perspective, the mesoporous nature of the manufactured entropy-stable ceramic film 100 may also be used for sensors, photocatalysis, and charge storage. In addition, the pores 108 may also serve as efficient templates or hosts for foreign substances, such as filling or trapping various molecules (e.g., catalysts, dyes, or magnetic substances). Advantageously, this allows the entropy-stabilized ceramic films 100 to be manufactured with general functions other than for protection and decoration purposes.

Advantageously, the present invention can support the fabrication of large area films. Since the surface of the entropy-stable alloy is shaped to form an anode and is directly anodized by anions, the physical properties of the film can be precisely controlled, and the prepared film has high uniformity over the entire anodized surface. Therefore, the present invention is highly compatible with mass production on an industrial scale.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Those skilled in the art will also appreciate that the present invention may include additional modifications to the method without affecting the overall functionality of the method.

Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge, unless otherwise indicated. It will be appreciated that, if any prior art information is referred to herein, this reference does not constitute an admission that the information forms part of the common general knowledge in the art (in any other country).