High-entropy oxide layer in-situ synthesis method based on water vapor oxidation technology and application of high-entropy oxide layer in-situ synthesis method

Abstract

The invention provides a high-entropy oxide layer in-situ synthesis method based on a water vapor oxidation technology, and belongs to the technical field of surface treatment. Aiming at the problems of high preparation temperature, serious component segregation, strong equipment dependence, difficulty in multi-metal synergistic oxidation regulation and the like of the high-entropy oxide layer in the prior art, low-temperature in-situ synthesis of the high-entropy oxide layer with the single-phase spinel or rock salt structure is realized through multi-metal precursor design, water vapor staged oxidation treatment and post-treatment. On the basis of a water vapor staged oxidation strategy, multi-metal synchronous oxidation is achieved by regulating and controlling the oxidation temperature, the oxidation time and the water vapor partial pressure, in the reaction of staged oxidation treatment, hydrogen escapes to inhibit local oxygen partial pressure, and it is ensured that the uniformity and performance of an oxidation layer are controllable. The process is green and environment-friendly, in-situ growth of the oxide layer is free of interface defects, the method is suitable for various metal element precursors, the process is efficient, and a low-cost and environment-friendly solution is provided for large-scale preparation of the high-entropy oxide layer.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of surface treatment, and particularly relates to a high-entropy oxide layer in-situ synthesis method based on water vapor oxidation technology and application thereof. BACKGROUND

[0002] The high-entropy oxide layer can form a dense and chemically inert surface structure due to its unique composition complexity and high configuration entropy effect, and exhibits significant potential in improving the corrosion resistance of materials. However, traditional synthesis methods such as sol-gel method, vapor deposition method and solid phase sintering method usually require complex process treatment or precise equipment, which is high in production cost and difficult to scale. There are already some researches on the preparation of high-entropy oxides using oxidation technology. For example, the patent document with publication number CN 117886590 A oxidizes high-entropy alloy precursor powder at high temperature in air atmosphere to generate high-entropy oxide ceramic, but due to process limitations, the preparation temperature is relatively high, and the prepared oxide ceramic cannot be directly used for surface coating protection. Ceramic materials are difficult to form a single-phase solid solution with uniform composition due to low diffusion rate, and the existing technology has obvious deficiencies in the coordination and regulation of multi-metal oxidation. For example, the patent document with publication number CN 114606457 A grows a high-entropy alloy oxide coating with a composition of (Mn,Cu)3O4 spinel layer, Fe oxide layer and NiCo oxide layer in a high-temperature high-oxygen-pressure environment. Due to the strong oxidizing nature of the oxygen environment, the reaction speed is fast, resulting in composition segregation.

[0003] High-temperature vapor oxidation is a relatively effective method for preparing surface oxides, which is low in cost and high in efficiency, but the oxide layer structure obtained by conventional oxidation often has defects such as poor density. In view of this problem, existing researches, such as the patent document with publication number CN 108517488 A, use ionized water vapor for high-temperature oxidation. The oxide structure prepared can be dense, which can greatly improve the corrosion resistance of the nitride layer, but its process is limited to single metal or simple alloy system, and there is a lack of effective regulation of multi-element synchronous oxidation of five or more high-entropy oxide layers.

[0004] In summary, the current preparation of high-entropy oxide layers is still limited by high energy consumption, high cost and high equipment requirements of high-temperature processes, and there are difficulties in coordinated oxidation regulation, which seriously hinders its industrial application. Therefore, developing a method for realizing multi-element synchronous oxidation at a lower temperature and low cost has become a key to using high-entropy oxide layers to in-situ enhance the corrosion resistance of material surfaces. SUMMARY

[0005] One of the purposes of the present application is to provide a high-entropy oxide layer in-situ synthesis method based on water vapor oxidation technology, which realizes the coordinated oxidation of multiple metals and the uniform distribution of components in the high-entropy oxide layer under the premise of low energy consumption and low cost.

[0006] The second object of the present application is to provide a high-entropy oxide layer based on water vapor oxidation technology, which realizes in-situ enhancement of corrosion resistance of material surface through multi-metal synergistic oxidation mechanism.

[0007] The technical solution adopted by the present application to achieve one of the objects is to provide a high-entropy oxide layer in-situ synthesis method based on water vapor oxidation technology, which uses in-situ alloying treatment to prepare a precursor coating containing any five of Fe, Co, Ni, Cu, Zn, Mn, Cr, and Al on the surface of the substrate; then uses a mixture of water vapor and inert gas to perform staged oxidation treatment on the precursor coating to obtain a high-entropy oxide layer; in the staged oxidation treatment, the temperature of the first stage is 400-600℃, and the volume percentage of water vapor in the mixed gas is 10%-40%; compared with the first stage, the temperature of the second stage is increased by 150-500℃, and the volume percentage of water vapor in the mixed gas is increased by 30%-50%.

[0008] The overall idea and invention principle of the present application are as follows: The present application proposes an innovative solution based on water vapor oxidation technology to solve the technical problem of uniformity of composition in the preparation of high-entropy oxide layer. According to the characteristics of multi-metal precursor composition, the dynamic control of water vapor oxidation process is realized to achieve the synergistic oxidation of high-activity metal elements and transition metal elements, ensuring the formation of single-phase high-entropy oxide layer.

[0009] The metal elements involved in the preparation of the precursor coating include any five of Fe, Co, Ni, Cu, Zn, Mn, Cr, and Al. The inventors have found through a large number of experiments that when five of the above eight metal elements are selected for combination, the oxidation kinetic characteristics of each element in the precursor coating can match the water vapor staged oxidation process proposed by the present application, realizing synchronous and uniform oxidation. Under the condition of water vapor staged oxidation, the oxidation rate difference of each metal element used in the present application is less than 15%, while the addition of other metals (such as Ti, Mo, V) will result in too large oxidation rate difference and cannot form a single-phase high-entropy oxide layer.

[0010] Further, the staged oxidation treatment includes two stages, namely a first stage of initial oxidation and a second stage of stable growth of the oxidation layer. In the first stage, the temperature is set to 400-600 DEG C, the time is 1-2 h, and the volume fraction of water vapor in the mixed gas is 10-40%. At the lower temperature of the first stage of oxidation treatment, the high-activity metal in the precursor coating will be preferentially oxidized and nucleated. Due to the escape of hydrogen during the water vapor oxidation process, the preferentially generated oxidation products will not form a dense layer to inhibit the oxidation of the low-activity metal, and at the same time, provide a diffusion path for the oxidation of the low-activity metal. Then in the second stage of oxidation treatment, the temperature and the volume fraction of water vapor are increased by a certain gradient, respectively. The escaped hydrogen further dilutes the local oxygen partial pressure and inhibits the over-oxidation of the high-activity metal. The low-activity components diffuse in the channels formed by the non-dense oxidation products and are synchronously oxidized. At the same time, the dehydrogenation of the transitional hydroxide also reduces the structural defects caused by hydrogen residues, thereby realizing the regulation of the oxidation degree and structure of the oxidation layer.

[0011] Further, the mixed raw material powder for preparing the precursor coating is composed of one of the following combinations of elemental metal powders: Fe, Cr, Ni, Mn, Zn; Fe, Co, Ni, Al, Cu; Co, Cr, Fe, Mn, Al; Ni, Cu, Cr, Al, Mn; Fe, Ni, Zn, Cr, Co; or Fe, Co, Ni, Cr, Al.

[0012] Further, with respect to the content of each elemental metal in the five-element mixed raw material powder, the present application, in addition to referring to the approximate equality of the molar ratio of each elemental metal in the high-entropy alloy (the content of each metal element is 12 at.%-28 at.%), also combines the characteristics of the water vapor oxidation process of the present application: on the one hand, the water vapor oxidation kinetic curves of each metal element are normalized and calculated to match the reaction rates of the water vapor oxidation reactions of each metal element, so as to obtain the atomic proportions that satisfy the synchronous oxidation of each element, i.e., the proportions of each element in the precursor; on the other hand, according to the calculation results of the thermodynamic compatibility of the oxides corresponding to each metal element with spinel or rock salt structures, the content of each element is adjusted to regulate the charge balance of different valence states, so as to ensure the formation of a uniform single-phase solid solution with thermodynamic metastable state characteristics during the water vapor high-temperature oxidation process, and effectively inhibit the element segregation and phase separation in the oxidation layer.

[0013] Preferably, the mixed raw material powder is a combination of elemental metal powders Fe, Cr, Ni, Mn, and Zn, and the mass percentage of each elemental metal powder is: Fe: 15%-35%, Cr: 10%-20%, Ni: 15%-35%, Mn: 10%-20%, and Zn: 5%-15%. More preferably, in the mixed raw material powder, the mass percentage of each elemental metal powder is: Fe: 20%-35%, Cr: 15%-20%, Ni: 25%-35%, Mn: 10%-15%, and Zn: 8%-15%.

[0014] In the present application, by designing multi-metal precursor components and dynamically controlling the oxidation process, the synergistic oxidation of high-activity elements such as Cr and Al and transition metals such as Fe, Co, and Ni can be achieved to form a single-phase high-entropy oxide layer, and the molar ratio of each metal element in the high-entropy oxide layer is substantially equal. In the staged oxidation process provided in the present application, the main reaction types involved are as follows: xM+yH2O→M x O y +xH2 wherein M is a metal element Fe, Co, Ni, Cu, Zn, Mn, Cr, or Al.

[0015] Further, the mesh number of the elemental metal powder is 100-200 mesh, and the mixed raw material powder is obtained by mixing using ball milling. The ball milling rate is 200-300 rpm, and the ball milling time is 3-5 h. Preferably, the ball milling is performed in an intermittent mode, i.e., the ball milling is performed in a mode of rotating for 20 min, stopping for 10 min, and then continuing to ball mill.

[0016] Further, before preparing the precursor coating, the mixed raw material powder is subjected to drying treatment at a temperature of 80-100°C for 6-8 h.

[0017] Further, the in-situ alloying treatment is performed in a protective gas (such as argon) atmosphere by laser cladding, plasma cladding, or thermal spraying. The present application performs in-situ alloying treatment on the mixed raw material powder containing elemental metal powders, so that each elemental metal is melted during the cladding process to form an alloy coating.

[0018] Preferably, the parameters of the laser cladding include: laser power 600-1200 W, scanning speed 4-8 mm / s, defocusing amount 12-15 mm, spot diameter 3-4 mm, protective atmosphere argon, and flow rate 5-15 L / min.

[0019] Further, the thickness of the precursor coating is 0.5-2 mm.

[0020] Further, the staged oxidation treatment is carried out in a controllable atmosphere reaction device (such as a tube furnace, a controllable atmosphere heat treatment furnace, etc.), and the inert gas in the mixed gas is argon.

[0021] Further, in the staged oxidation treatment, the time of the first stage is 2-4 h, and the time of the second stage is 1-4 h. The suitable oxidation time can make the water vapor diffuse more uniformly in the inside of the precursor coating, and the prepared high-entropy oxide layer has a certain thickness.

[0022] Further, after the oxidation treatment in the second stage, the high-entropy oxide layer is subjected to heat treatment, the heat treatment is carried out in an inert atmosphere, the temperature of the heat treatment is 750-950 DEG C, and the holding time is 0.5-2 h. The high-entropy oxide layer obtained by the heat treatment is subjected to densification treatment, so as to reduce the metastable defects such as micro-cracks and local lattice distortion, and further improve the uniformity and stability of the composition of the high-entropy oxide layer.

[0023] The technical scheme for realizing the second purpose of the present application is to provide a high-entropy oxide layer formed on the surface of a substrate by using the in-situ synthesis method of the high-entropy oxide layer according to the first purpose of the present application.

[0024] Preferably, in the high-entropy oxide layer, the atomic percentage of O element is 25 at.%-30 at.%, and the atomic percentage of each metal element is 14 at.%-15.5 at.%.

[0025] Compared with the prior art, the present application has the following beneficial effects: (1) The in-situ synthesis method of the high-entropy oxide layer provided by the present application uses a combination of metal elements with oxidation kinetic characteristics matched with the water vapor staged oxidation process to prepare a precursor coating, and adjusts the content of each metal element in the precursor coating based on the characteristics of the water vapor oxidation technology, so as to promote the synchronous oxidation of each metal element. In the staged oxidation process, the hydrogen gas generated by the reaction can reduce the local oxygen partial pressure, inhibit the excessive oxidation of the surface, and maintain the reaction uniformity. At the same time, by changing the oxidation temperature, time and water vapor partial pressure and other parameters, the oxidation thermodynamic needs of different metal elements can be met, and the thickness, density and stability of the oxide layer can be controlled.

[0026] (2) The in-situ synthesis method of the high-entropy oxide layer provided by the present application is efficient, the preparation period of the high-entropy oxide layer is short, and the method can be adapted to different methods such as laser cladding and plasma cladding to prepare an alloy precursor. The prepared high-entropy oxide layer grows in-situ on the surface of the substrate, and is combined well without the risk of interface peeling. In addition, water vapor is a green oxidizing agent, the by-product hydrogen gas can be recycled, and there is no toxic gas emission, which provides an efficient, low-cost and environmentally friendly solution for the large-scale preparation of high-entropy oxide layers. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A process flow chart of the in-situ synthesis method of a high entropy oxide layer based on water vapor oxidation technology provided in an embodiment of the present invention; Figure 2 Calculation results of Gibbs free energy of reaction of various metal elements during the preparation of the high entropy oxide layer provided in Example 1 of the present invention; Figure 3 The SEM image and EDS results of the high entropy oxide layer prepared in Example 1; Figure 4 This is the XRD pattern of the high entropy oxide layer prepared in Example 1. DETAILED DESCRIPTION

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0030] like Figure 1 As shown, an embodiment of the present invention provides an in-situ synthesis method of a high entropy oxide layer based on water vapor oxidation technology, comprising the following steps: Step 1: weigh the metal element powders of any five metal elements among Fe, Co, Ni, Cu, Zn, Mn, Cr, and Al in proportion, mix them evenly by ball milling, and dry them to obtain a mixed raw material powder; the mesh size of each metal element powder is 100-200 mesh, and they are mixed by ball milling to obtain a mixed raw material powder; the ball milling rate is 200-300 rpm, and the ball milling time is 3-5 hours; the ball milling treatment adopts an intermittent ball milling method, which rotates forward for 20 minutes, stops for 10 minutes, and then continues the ball milling mode in a cycle; then the mixed raw material powder is dried, and the drying temperature is 80-100°C and the time is 6-8 hours.

[0031] Step 2: The raw material powder obtained in step 1 is in-situ alloyed by laser cladding or plasma spraying technology to prepare a precursor coating with a thickness of 0.5-2 mm on the surface of the substrate.

[0032] Step 3: The precursor coating surface obtained in step 2 is polished flat and placed in a controllable atmosphere reaction device tube furnace, and a mixed gas of water vapor and argon is introduced to obtain a high-entropy oxide layer; in the staged oxidation process, the temperature of the first stage is 400-600 DEG C, the volume percentage of water vapor in the mixed gas is 10%-40% (water vapor partial pressure is 10.13-40.53 kPa; argon partial pressure is 60.80-91.20 kPa), and the time is 2-4h; the temperature of the second stage is increased by 150-500 DEG C relative to the first stage, the volume percentage of water vapor in the mixed gas is increased by 30%-50% (water vapor partial pressure is 40.53-91.19 kPa; argon partial pressure is 10.13-60.80 kPa), and the time is 1-4h.

[0033] Step 4: The high-entropy oxide layer obtained in step 3 is heat treated to achieve densification of the oxide layer; the heat treatment is carried out in an inert atmosphere, the heat treatment temperature is 750-950 DEG C, and the holding time is 0.5-2h.

[0034] The application will be further described below in conjunction with specific examples, but not as a limitation of the application.

[0035] Example 1 The present embodiment provides an in-situ synthesis method of Fe-Cr-Ni-Mn-Zn-O high-entropy oxide layer based on water vapor oxidation technology, and the specific steps are as follows: Step 1: Select Fe, Cr, Ni, Mn and Zn five kinds of metal elements, weigh 100g of elemental metal powder with mass percentage of 20%:20%:35%:10%:15%, particle size of 200 mesh, and obtain mixed raw powder by planetary ball mill with ball-to-material ratio of 2:1 and rotation speed of 300 rpm for 5 hours, and then dry in a 100 DEG C vacuum drying oven for 8 hours.

[0036] Step 2: Select a 100mmx100mmx10mm Q235 stainless steel substrate, and use laser cladding technology to cladding the raw powder on the surface of the substrate to form a precursor coating with a thickness of about 2mm. In the laser cladding, the laser power is 1000W, the scanning speed is 6mm / s, the defocusing amount is 12mm, the spot diameter is 3mm, the protective atmosphere is argon, and the flow rate is 10L / min.

[0037] Step 3: The coating sample is placed in a tube furnace, and a mixed gas of water vapor and argon is introduced, the volume fraction of water vapor is 40%, and the temperature is kept at 600 DEG C for 2 hours; then a mixed gas with a water vapor volume fraction of 90% is introduced, and the temperature is kept at 900 DEG C for 4 hours.

[0038] Step 4: After the oxidation is completed, an argon atmosphere is passed, and the temperature is maintained at 850°C for 2 hours, and finally cooled to room temperature to obtain a high-entropy oxide layer with an average thickness of 0.38 mm.

[0039] The feasibility of the water vapor oxidation reaction in this embodiment is verified by thermodynamic calculation. The Gibbs free energy (ΔG) of each reaction is shown in Table 1. Figure 2 As can be seen, the ΔG of the oxidation reaction of all metal elements is negative within the set temperature range, indicating that the reaction is thermodynamically spontaneous.

[0040] The high-entropy oxide layer prepared in this embodiment is observed by scanning electron microscopy (SEM) and element surface distribution analysis is performed by energy dispersive spectrometer (EDS), as shown in FIG. 2. Figure 3 The results show that the surface of the oxide layer presents a continuous and dense structure without obvious pores or cracks. In the high-entropy oxide layer, the atomic percentage of each element is Fe: 15.56%, Cr: 14.42%, Ni: 14.23%, Mn: 14.87%, Zn: 14.15%, and O: 27.17%. The atomic percentage deviation of Fe, Cr, Ni, Mn, and Zn elements is not more than 5%.

[0041] The high-entropy oxide layer prepared in this embodiment is analyzed by XRD, as shown in FIG. 3. Figure 4 The results show that the composition of the oxide layer is (FeCrNiMnZn)3O4 with a spinel structure, confirming that the high-entropy oxide layer has excellent composition uniformity and structural integrity, enabling simultaneous oxidation of each metal element without element or phase segregation.

[0042] Embodiment 2 This embodiment provides an in-situ synthesis method for Fe-Cr-Ni-Mn-Zn-O high-entropy oxide layer based on water vapor oxidation technology. The specific steps are as follows: Step 1: Select Fe, Cr, Ni, Mn, and Zn metal elements, and weigh 100 g of elemental metal powder with a mass percentage of 35%:15%:25%:15%:10%. The particle size is 100 mesh. The mixed raw material powder is obtained by planetary ball mill with a ball-to-material ratio of 1:1 and a rotation speed of 200 rpm for 3 hours, and then dried in a vacuum drying oven at 80°C for 6 hours.

[0043] Step 2: Select a 100mm×100mm×10mm Q235 stainless steel substrate, and use plasma cladding to clad the raw material powder on the surface of the substrate to form a precursor coating with a thickness of about 0.5 mm.

[0044] Step 3: Place the coating sample in a tube furnace and introduce a mixture of water vapor and argon with a water vapor volume fraction of 10% at 400°C for 4 hours. Then introduce a mixture of water vapor with a volume fraction of 60% at 900°C for 1 hour.

[0045] Step 4: After the oxidation is completed, an argon atmosphere is introduced, and the temperature is kept at 950°C for 0.5 hours, and finally cooled to room temperature to obtain a high entropy oxidation layer with an average thickness of 0.13 mm.

[0046] Testing and analysis showed that the high-entropy oxide layer produced in this embodiment exhibited a continuous, dense structure with no apparent holes or cracks. The atomic percentage of oxygen in the high-entropy oxide layer was 38.09 at.%, and the atomic percentages of the various metal elements ranged from 9.35 at.% to 17.51 ​​at.%, meeting the compositional requirements for a high-entropy oxide layer.

[0047] Example 3 This embodiment provides an in-situ synthesis method of a Fe-Cr-Ni-Mn-Zn-O high entropy oxide layer based on water vapor oxidation technology, and the specific steps are as follows: Step 1: Select five metal elements, Fe, Cr, Ni, Mn, and Zn, and weigh 100 g of single metal powder according to the mass percentage of 35%:15%:30%:12%:8%. The particle size is 100 mesh. Use a planetary ball mill with a ball-to-material ratio of 1:1 and a speed of 200 rpm for 3 hours to obtain a mixed raw material powder, which is then dried in a vacuum drying oven at 80°C for 6 hours.

[0048] Step 2: Select a Q235 stainless steel substrate with a size of 100 mm × 100 mm × 10 mm, and use laser cladding technology to clad the raw material powder on the surface of the substrate to form a precursor coating with a thickness of about 1.5 mm.

[0049] Step 3: Place the coating sample in a tube furnace and introduce a mixture of water vapor and argon with a water vapor volume fraction of 40% at 600°C for 4 hours. Then introduce a mixture of water vapor with a volume fraction of 90% at 750°C for 4 hours.

[0050] Step 4: After the oxidation is completed, an argon atmosphere is introduced, and the temperature is kept at 750°C for 2 hours, and finally cooled to room temperature to obtain a high entropy oxidation layer with an average thickness of 0.25 mm.

[0051] Testing and analysis showed that the high-entropy oxide layer produced in this embodiment exhibited a continuous, dense structure with no apparent holes or cracks. The atomic percentage of oxygen in the high-entropy oxide layer was 46.88 at.%, and the atomic percentages of the various metal elements ranged from 7.69 at.% to 15.39 at.%, meeting the compositional requirements for a high-entropy oxide layer.

[0052] Embodiment 4 The embodiment provides an in-situ synthesis method of a Fe-Co-Ni-Al-Cu-O high-entropy oxide layer based on a water vapor oxidation technology, and specific steps are as follows. Step 1: five metal elements Fe, Co, Ni, Al and Cu are selected, and 100g of elemental metal powder is weighed according to the mass percentage of 35%:15%:15%:15%:20%, the particle size is 200 meshes, the planetary ball mill is used for ball milling at a ball-to-material ratio of 2:1 and a rotating speed of 300 rpm for 5 hours, and then the mixed raw material powder is dried in a 100 DEG C vacuum drying box for 8 hours.

[0053] Step 2: a 100mm*100mm*10mm Q235 stainless steel substrate is selected, the raw material powder is cladded on the surface of the substrate by using a laser cladding technology, and a precursor coating with a thickness of about 2mm is formed.

[0054] Step 3: the coating sample is placed in a tube furnace, a mixed gas of water vapor and argon is introduced, the volume fraction of water vapor is 10%, and the sample is kept at 600 DEG C for 2 hours, then a mixed gas with a water vapor volume fraction of 40% is introduced, and the sample is kept at 900 DEG C for 4 hours.

[0055] Step 4: after the oxidation is completed, argon atmosphere is introduced, the sample is kept at 750 DEG C for 2 hours, and finally cooled to room temperature, and a high-entropy oxide layer with an average thickness of 0.37mm is obtained.

[0056] Through test analysis, the high-entropy oxide layer prepared in the embodiment has a continuous and dense structure and no obvious holes or cracks. In the high-entropy oxide layer, the atomic percentage of O element is 54.77at.%, and the atomic percentage of each metal element is 6.04at.%-14.11at.%, which meets the composition requirement of the high-entropy oxide layer.

[0057] Embodiment 5 The embodiment provides an in-situ synthesis method of a Fe-Co-Ni-Al-Cu-O high-entropy oxide layer based on a water vapor oxidation technology, and specific steps are as follows. Step 1: five metal elements Fe, Co, Ni, Al and Cu are selected, and 100g of elemental metal powder is weighed according to the mass percentage of 15%:35%:20%:5%:25%, the particle size is 200 meshes, the planetary ball mill is used for ball milling at a ball-to-material ratio of 2:1 and a rotating speed of 300 rpm for 5 hours, and then the mixed raw material powder is dried in a 100 DEG C vacuum drying box for 8 hours.

[0058] Step 2: a 100mm*100mm*10mm Q235 stainless steel substrate is selected, the raw material powder is cladded on the surface of the substrate by using a laser cladding technology, and a precursor coating with a thickness of about 1mm is formed.

[0059] Step 3: The coating sample was placed in a tube furnace, and a mixed gas of water vapor and argon was introduced, with a water vapor volume fraction of 20%, at 500°C for 2 hours, and then a mixed gas with a water vapor volume fraction of 60% was introduced, at 900°C for 4 hours.

[0060] Step 4: After oxidation was completed, an argon atmosphere was introduced, at 950°C for 1 hour, and finally cooled to room temperature, to obtain a high-entropy oxide layer with an average thickness of 0.31 mm.

[0061] Through test analysis, the high-entropy oxide layer prepared in this embodiment has a continuous and dense structure on the surface and no obvious pores or cracks. In the high-entropy oxide layer, the atomic percentage of O element is 64.22 at.%, and the atomic percentage of each metal element is 4.74 at.%-10.68 at.%, meeting the composition requirements of the high-entropy oxide layer.

[0062] The above is only the preferred embodiment of the present application, and does not limit the implementation and protection scope of the present application. For those skilled in the art, it should be realized that any equivalent replacement and obvious changes made by applying the content of the present application should be included in the protection scope of the present application.

Claims

1. A method for in-situ synthesis of a high entropy oxide layer based on water vapor oxidation technology, characterized in that: A precursor coating containing any five metal elements of Fe, Co, Ni, Cu, Zn, Mn, Cr, and Al is prepared on the surface of a substrate by an in-situ alloying method; the precursor coating is then oxidized in stages using a mixture of water vapor and an inert gas to obtain a high-entropy oxide layer; In the staged oxidation treatment, the temperature of the first stage is 400-600°C, and the volume percentage of water vapor in the mixed gas is 10%-40%; compared with the first stage, the temperature of the second stage is increased by 150-500°C, and the volume percentage of water vapor in the mixed gas is increased by 30%-50%.

2. The in-situ synthesis method of a high entropy oxide layer according to claim 1, wherein: The mixed raw material powder used to prepare the precursor coating is composed of a combination of the following metal element powders: Fe, Cr, Ni, Mn, Zn; Fe, Co, Ni, Al, Cu; Co, Cr, Fe, Mn, Al; Ni, Cu, Cr, Al, Mn; Fe, Ni, Zn, Cr, Co or Fe, Co, Ni, Cr, Al.

3. The in-situ synthesis method of a high entropy oxide layer according to claim 2, wherein: The mixed raw material powder adopts a combination of metal element powders Fe, Cr, Ni, Mn, and Zn; the mass percentage of each metal element powder is: Fe: 15%-35%, Cr: 10%-20%, Ni: 15%-35%, Mn: 10%-20%, Zn: 5%-15%.

4. The in-situ synthesis method of a high entropy oxide layer according to claim 3, wherein: In the mixed raw material powder, the mass percentage of each metal element powder is: Fe: 20%-35%, Cr: 15%-20%, Ni: 25%-35%, Mn: 10%-15%, Zn: 8%-15%.

5. The in-situ synthesis method of a high entropy oxidation layer according to claim 2, wherein: The mesh number of the metal element powder is 100-200 mesh, and the mixed raw material powder is obtained by ball milling; the ball milling speed is 200-300 rpm, and the ball milling time is 3-5 hours.

6. The in-situ synthesis method of a high entropy oxidation layer according to claim 2, characterized in that: Before preparing the precursor coating, the mixed raw material powder is dried at a temperature of 80-100° C. for 6-8 hours.

7. The in-situ synthesis method of a high entropy oxide layer according to claim 1, characterized in that: The in-situ alloying treatment method includes one of laser cladding and plasma cladding; the thickness of the precursor coating is 0.5-2 mm.

8. The in-situ synthesis method of a high entropy oxide layer according to claim 1, wherein: In the staged oxidation treatment, the first stage lasts for 2-4 hours, and the second stage lasts for 1-4 hours.

9. The in-situ synthesis method of a high entropy oxidation layer according to claim 1, characterized in that: After the second stage of oxidation treatment, the high entropy oxide layer is heat treated; the heat treatment is carried out in an inert atmosphere, the heat treatment temperature is 750-950° C., and the holding time is 0.5-2 hours.

10. A high entropy oxide layer, characterized in that The high entropy oxidation layer is formed on the surface of the substrate by using the in-situ synthesis method according to any one of claims 1 to 9.

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