High-entropy oxide ceramic reinforced alloy composite coating as well as preparation method and application thereof

Abstract

The invention discloses a high-entropy oxide ceramic reinforced alloy composite coating and a preparation method thereof, and belongs to the technical field of metal-based composite coatings. The composite coating is composed of an alloy phase and a high-entropy oxide ceramic phase, and the ceramic phase is a five-element high-entropy ferrite oxide. The preparation method of the composite coating comprises the following steps: weighing the raw materials, and carrying out ball-milling mixing and drying treatment; the base body is pretreated; an adhesive is added into the mixed raw material powder to be blended into paste, the paste is pressed on the surface of a base body and dried to form a preset coating, and cladding is directly conducted on the preset coating; or cladding the mixed raw material powder on the surface of the matrix by adopting a synchronous powder feeding technology through a laser cladding process to obtain the final composite coating. The cocktail effect of the high-entropy oxide ceramic is utilized, the prepared composite coating is well combined with a matrix, and the comprehensive performance is excellent. In addition, the technological process is simple and environmentally friendly, and has the flexibility advantages of efficient preparation and performance regulation and control.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal-based composite coatings, and specifically relates to a high-entropy oxide ceramic reinforced alloy composite coating and a preparation method thereof, and also relates to the application of the high-entropy oxide ceramic reinforced alloy composite coating in the protection of inert anodes for electrolytic aluminum. Background Art

[0002] The main aluminum production method currently used in the aluminum electrolysis industry is the Hall-Héorult process, which is a method of producing aluminum by electrolyzing alumina-cryolite melt. 2 O 3 +3C→4Al+3CO 2 Not only does it produce a lot of CO 2 Greenhouse gases, fluorine-containing pollutants and asphalt fumes and other harmful substances will also be released. At the same time, the poor conductivity of the carbon anode leads to low electrical efficiency. The inert anode reacts 2Al 2 O 3 →4Al+3O 2 It can completely eliminate carbon emissions and become a key research direction for green metallurgy. However, the inert anode needs to work stably for a long time in high-temperature, highly corrosive cryolite molten salt, which places strict requirements on the material's conductivity, resistance to molten salt corrosion, and interface bonding strength.

[0003] Metal ceramic materials are considered ideal candidates for inert anode materials because they have both high conductivity of the metal phase and corrosion resistance of the ceramic phase. However, the contradiction between their preparation process and performance restricts their industrial application. For example, the nickel-based metal oxide ceramic anode proposed in patent CN107083510A needs to be prepared by pressing and high-temperature sintering, which is a complex process and prone to internal pores; although the precious metal-aluminum oxide composite coating used in patent CN101736368 has excellent corrosion resistance, the high cost of precious metals makes it difficult to apply on a large scale, and the ZrB introduced in patent CN113186569A 2 Although the ceramic phase can improve the corrosion resistance, it is prone to thermal stress cracking due to the difference in thermal expansion coefficient between the ceramic phase and the metal matrix.

[0004] In view of the above-mentioned shortcomings of metal ceramic materials, surface coating technology is an effective way to improve the high-temperature oxidation and molten salt corrosion of inert anodes. For example, the patent with application number 201310671469.3 prepared a composite protective layer composed of a bottom Ni-Fe-based alloy layer and an outer metal ceramic layer, but the interface obtained by spraying is not metallurgical and is prone to peeling under long-term corrosion of molten salt. Laser cladding technology has attracted attention because it can achieve metallurgical bonding. For example, the Chinese invention patent with application number 202310354715.6 discloses a method for preparing high-entropy ceramic reinforced metal-based composite materials using laser cladding, but the performance of the coating prepared by it in the high-temperature molten salt environment of aluminum electrolysis is still limited.

[0005] In summary, the existing inert anode surface coating technology is difficult to balance low cost, high interface bonding strength and long-term stability in molten salt environment. 2 O 3 、NiFe 2 O 4 Based on this, it is an urgent technical problem to provide a composite coating with excellent high temperature stability, electrical conductivity, corrosion resistance and mechanical properties to better meet the application requirements of electrolytic aluminum inert anode protection. Summary of the invention

[0006] One of the purposes of the present invention is to provide a high entropy oxide ceramic reinforced alloy composite coating having excellent high temperature stability, electrical conductivity, corrosion resistance and mechanical properties, and good interface bonding performance with a substrate.

[0007] The second object of the present invention is to provide a method for preparing a high-entropy oxide ceramic reinforced alloy composite coating with a simple and efficient preparation process and good interface bonding performance.

[0008] The third object of the present invention is to provide a high entropy oxide ceramic reinforced alloy composite coating for use in inert anode protection of electrolytic aluminum.

[0009] The technical solution adopted by the present invention to achieve one of the purposes is: to provide a high entropy oxide ceramic reinforced alloy composite coating, which is formed on the surface of the substrate by laser cladding of raw material mixed powder; The raw material mixed powder comprises 60wt%-95wt% of alloy phase and 5wt%-40wt% of ceramic phase in terms of weight percentage; The alloy phase includes at least three metal elements: Cu, Ni and Fe; The ceramic phase is formed by mixing oxides corresponding to any five metal elements of Co, Ni, Cu, Zn, Al, Mn, Ti, Mo, and V with iron oxide in a molar ratio of the metal elements of 1:1:1:1:1:10.

[0010] The overall idea and inventive principle of the present invention are as follows: The present invention aims to solve the problems of high cost and complex process in the existing technology, as well as the problems of poor interface bonding and poor high-temperature stability in traditional metal ceramic coatings, and provides a high-entropy oxide ceramic reinforced alloy composite coating. Based on the excellent temperature resistance and molten salt corrosion resistance of the oxide ceramic phase, the composite coating introduces the concept of "high-entropy oxide ceramic phase", which can not only give play to the corrosion resistance advantages of the spinel structure, but also give play to the enhancement effect of the oxides of various metal elements through the "cocktail effect" of high-entropy ceramics, thereby improving the mechanical properties and high-temperature service capability of the metal-ceramic composite coating under aluminum electrolysis conditions.

[0011] In the selection of alloy phase components, the present invention adopts a Cu-Ni-Fe alloy system that can meet the electrical conductivity and corrosion resistance requirements of the inert anode. At the same time, the three metal elements Cu, Ni and Fe can also achieve cross-phase synergy with the metal elements in the high entropy oxide ceramic phase.

[0012] In terms of the composition design of the ceramic phase, the ceramic phase of the present invention is composed of oxides corresponding to any five metal elements of Co, Ni, Cu, Zn, Al, Mn, Ti, Mo, and V mixed with iron oxide in a certain proportion. After laser cladding, the coating contains a high-entropy ferrite oxide ceramic reinforcement phase, which has both high-entropy effect and spinel structure, significantly improving the comprehensive performance of the coating (including mechanical properties, electrical conductivity, corrosion resistance, etc.).

[0013] Furthermore, in order to ensure the stable formation of the spinel ferrite oxide ceramic structure and to ensure the generation of high entropy effect in the reinforcement phase, the present invention limits the mixing of the oxides corresponding to the metal elements in the ceramic phase and the iron oxide according to the molar ratio of the metal elements of 1:1:1:1:1:10. This ratio can ensure that the metal elements of various oxide ceramics form a spinel structure during the powder mixing process, and the chemical formula is AB 2 O 4 , that is, the octahedral center formed by 6 oxygen atoms, and the iron element occupies the B position; other metal ions are located at the A position, that is, the tetrahedral center formed by 4 oxygen atoms, and the ratio of the sum of the molar ratios of the metal elements occupying the A position to the iron element is 1:2. Because of the requirement of the high entropy effect at the A position, that is, the molar ratios of the elements are equal, it is necessary to control the molar ratio of other metal elements added to the ceramic phase to iron to be "1:1:1:1:1:10". Under the above ratio conditions, after the ceramic phase is laser clad, the interaction of the cations at the AB sites of the spinel structure and the "cocktail effect" of the high entropy ceramic ensure the overall conductivity, mechanical properties and corrosion resistance of the coating, enabling it to play a better role in the protection of the electrolytic aluminum inert anode.

[0014] Further, it is found that for the composition of the raw material mixed powder, when the ceramic phase accounts for less than 5 wt%, it is difficult to detect the high entropy ferrite oxide ceramic phase in the coating, that is, the high entropy ceramic strengthening effect cannot be formed; and as the ceramic phase accounts for more than 15 wt%, the fluidity of the metal ceramic mixed powder gradually deteriorates. Under a specific laser cladding device, it is not suitable to use a laser cladding method with synchronous powder feeding, which limits subsequent processing. At the same time, when the ceramic phase accounts for too high a proportion, exceeding 40wt%, the coating will have more serious process problems, such as cracks and more pores. Preferably, the composition of the raw material mixed powder, by weight percentage, is 60wt%-95wt% for the alloy phase and 5wt%-40wt% for the ceramic phase. More preferably, the alloy phase is 85wt%-95wt% and the ceramic phase is 5wt%-15wt%.

[0015] Furthermore, the composition of the alloy phase is, by weight percentage, 20wt%-35wt% of Cu, 20wt%-40wt% of Ni, and 35wt%-60wt% of Fe.

[0016] Furthermore, the alloy phase also includes Cr and / or Al elements, and the addition amount of Cr and / or Al is 0.01wt%-15wt%. Among them, the introduction of Cr or Al elements can further increase the corrosion resistance of the matrix. Since the metal elements of the alloy phase and the metal elements of the ceramic phase have cross-phase synergy, taking the metal element Al as an example, when the alloy phase contains Al elements when the alloy phase and the ceramic are the same, the Al element is distributed in a gradient in the alloy / ceramic, which can simultaneously achieve the improvement of the oxidation resistance of the alloy side and the enhancement of the high temperature stability of the spinel structure.

[0017] Furthermore, in the high-entropy oxide ceramic reinforced alloy composite coating, the content of high-entropy ferrite oxide is 4.24wt%-46.41wt%.

[0018] The technical solution adopted by the present invention to achieve the second purpose is: to provide a method for preparing the high entropy oxide ceramic reinforced alloy composite coating according to one of the purposes of the present invention, comprising the following steps: S1, weighing and mixing raw materials according to the proportion of each component, and subjecting the raw materials to ball milling and drying to obtain raw material mixed powder; S2, performing surface treatment and preheating on the substrate to obtain a cladding substrate; S3. Laser cladding the surface of the cladding substrate using the raw material mixed powder by synchronous powder feeding; or first forming a pre-coating on the surface of the cladding substrate with the raw material mixed powder, and then laser cladding the pre-coating to obtain a high entropy oxide ceramic reinforced alloy composite coating.

[0019] Furthermore, the drying treatment in step S1 is performed at a temperature of 70-90° C. and for a time of 6-8 hours.

[0020] Furthermore, in step S1, the mesh size of each component raw material powder is 100-300 mesh, the ball-to-material ratio of the ball milling treatment is 1-2:1, the ball milling speed is 280-300 rpm, after 20 minutes of forward rotation, it stops for 10 minutes, and the ball milling time is 6-7 hours.

[0021] Furthermore, in step S2, the surface pretreatment of the metal substrate includes mechanical grinding, the preheating temperature is 700-800°C, and the treatment time is 3-5h.

[0022] Further, in step S3, the parameters of the laser cladding include: laser power of 1200-2000W, scanning speed of 4-10mm / s, defocus of 10-15mm, and spot diameter of 3-4mm. In the laser cladding, argon is used as a protective gas, the argon flow rate is 8-20L / min, and the laser performs multiple overlapping claddings on the substrate from left to right.

[0023] Furthermore, in step S3, the synchronous powder feeding speed is 10-15 g / min.

[0024] Furthermore, in step S3, the preparation method of the pre-coating layer is: mixing the raw material mixed powder with the binder into a paste mixture, applying the paste mixture to the surface of the cladding substrate, pressing and drying to obtain the pre-coating layer. Preferably, the binder is one of polyvinyl alcohol or water glass, the pressing pressure is 100-150Mpa, and the thickness of the pre-coating layer is 0.5-1.5mm.

[0025] In step S3 of the present invention, two laser cladding methods are provided: synchronous powder feeding and pre-coating, which can be flexibly selected according to different application scenarios. Among them, the pre-coating method can avoid the problem of poor fluidity when there is a lot of ceramic powder, reduce the probability of pores, and realize local cladding of special-shaped parts; while synchronous powder feeding can realize efficient and continuous processing of coating, reduce cladding heat accumulation, and improve bonding strength.

[0026] In the preparation method provided by the present invention, the selection and optimization of laser cladding process parameters are based on the coupling mechanism of the thermal sensitivity of the high entropy oxide ceramic reinforcement phase and the melting behavior of the metal matrix. In the traditional process, the conventional laser power is difficult to meet the eutectic requirements of the high entropy ceramic phase and the metal matrix, resulting in low interface bonding strength of the cladding layer and uneven distribution of the ceramic phase; and too high a scanning speed can easily cause the molten pool to solidify too fast, resulting in insufficient cladding layer height and microcracks, while too low a scanning speed can easily lead to excessive dilution of the matrix and thermal decomposition of the high entropy ceramic phase. For the high entropy oxide (pentanoid high entropy ferrite) and alloy system in the present invention, the above-mentioned laser cladding process parameters are determined by pre-analyzing the matrix and raw materials and conducting relevant experiments. It should be noted that the above process parameters do not have a simple linear relationship, and their optimal combination needs to be determined in combination with the composition characteristics and crystal structure stability of the alloy phase and the high entropy ceramic phase, and cannot be obtained by conventional linear extrapolation.

[0027] The technical solution adopted by the present invention to achieve the third purpose is: to provide a high-entropy oxide ceramic reinforced alloy composite coating according to one of the purposes of the present invention or a high-entropy oxide ceramic reinforced alloy composite coating prepared by the preparation method described in the second purpose of the present invention for use in the protection of electrolytic aluminum inert anodes.

[0028] The high-entropy oxide ceramic reinforced alloy composite coating prepared by the present invention has high hardness, excellent high-temperature conductivity and molten salt corrosion resistance. It is coated on the substrate surface of the electrolytic aluminum inert anode assembly (steel claws, anode hangers, etc.), which can improve the high-temperature resistance and resistance to molten salt corrosion of the anode assembly, provide better protection for the anode assembly in the harsh external environment of electrolytic aluminum, and extend the service life of the anode assembly.

[0029] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention introduces a spinel structured high-entropy ferrite oxide ceramic reinforcement phase with excellent electrical conductivity and corrosion resistance into the alloy coating. Through the "cocktail effect" of high-entropy oxide ceramics and the synergistic effect of multi-metal elements, the comprehensive performance of the composite coating is improved while achieving gradient matching of the thermal expansion coefficients of the ceramic phase and the metal matrix.

[0030] (2) The present invention gives full play to the advantages of laser cladding technology, namely, short process and high efficiency. It has a simple preparation process, good coating condition and is environmentally friendly, and can realize in-situ preparation of composite coatings. At the same time, the conductivity, thermal stability and mechanical properties of the coating can be precisely controlled by changing the raw material composition and process parameters, and can adapt to different industrial application scenarios such as electrolytic aluminum and chlor-alkali industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1A process flow chart of a high entropy oxide ceramic reinforced alloy composite coating and a preparation method thereof provided in an embodiment of the present invention; Figure 2 is a cross-sectional metallographic image of the high entropy oxide ceramic reinforced alloy composite coating in Example 1; Figure 3 The microstructure scanning electron microscope (SEM) image of the interface transition zone of the composite coating of Example 1; Figure 4 The microhardness distribution curves from the substrate to the surface layer of the composite coating prepared in Example 1 and the comparative example are shown; Figure 5 The conductivity of the composite coating prepared in Example 1 and the comparative example varies with temperature; Figure 6 The graph is a quality change curve of the composite coating prepared in Example 1 and the comparative example during the corrosion process. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] 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.

[0034] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0035] The compositions of the alloy phase and the ceramic phase in each embodiment of the present invention are shown in Table 1 below, and the parameters of the laser cladding in each embodiment are shown in Table 2 below.

[0036] Table 1

[0037] Table 2

[0038] Example 1 This embodiment provides a high entropy oxide ceramic reinforced alloy composite coating, and the preparation method thereof comprises the following steps: Step 1: Determine the alloy phase composition is copper, iron and nickel, weigh the corresponding mass according to Cu 20wt%, Ni 20wt%, Fe 60wt%, and the particle size is 200 mesh. Determine the use of CoO, NiO, CuO, ZnO, Al 2 O 3 , Fe2 O 3 The composition of the high entropy oxide ceramic reinforcement phase is calculated according to the molar ratio of each component. The raw material mass is weighed, and CoO 7.49g, NiO 7.47g, CuO 8g, ZnO 8.14, Al 2 O 3 5.1g, Fe 2 O 3 159.69g (element molar ratio Co: Ni: Cu: Zn: Al: Fe = 1:1:1:1:1:10), the particle size is about 200 mesh; determine the proportion of high entropy oxide ceramic powder to be 5wt%, weigh 95g of copper iron nickel powder and 5g of high entropy oxide ceramic powder, and intermittently ball mill for 7h in a planetary ball mill (ball-to-material ratio 2:1, speed 300rpm) to obtain a uniformly distributed mixed raw material powder. The mixed powder was placed in a vacuum drying oven at 80℃ and dried for 7h.

[0039] Step 2: Select Q235 with a size of 100 mm × 100 mm × 10 mm as the substrate for laser cladding, remove impurities on the surface of the substrate by mechanical grinding, place it in a preheating furnace and heat it to 800 °C at 5 °C / min, and keep it warm for 5 hours.

[0040] Step 3: Add 4% polyvinyl alcohol solution to the mixed raw material powder obtained in step 1, stir until a uniform paste is formed, and then apply it to the surface of the metal substrate pretreated in step 2. Next, place the coated substrate in a mold and press it under a pressure of 150Mpa to form a pre-coating with a thickness of 1mm. The pre-coating was placed in a vacuum drying oven at 80°C and dried for 7h. Using laser cladding technology, the pre-coating was clad under the conditions of process parameters of laser power 1200W, scanning speed 4mm / s, spot diameter 3.2mm, defocus 15mm, and argon protection flow rate 12L / min to obtain a high-entropy oxide ceramic reinforced alloy composite coating. Among them, the content of high-entropy ferrite oxide is 4.24wt%.

[0041] The high entropy oxide ceramic reinforced alloy composite coating prepared in this embodiment was observed using an optical microscope. Figure 2 As shown in the figure, it can be seen that the composite coating is well metallurgically bonded to the substrate, and the grain size distribution in different regions is relatively uniform. The microstructure of the interface transition zone of the composite coating of this embodiment is observed using a scanning electron microscope (SEM). Figure 3 As shown in the figure, it can be seen that the fusion line of the coating is flat and smooth, without defects such as cracks and inclusions, which further indicates that the interface bonding between the two is good.

[0042] In the high entropy oxide ceramic strengthening phase of this embodiment, Cu element forms CuFe 2 O 4The spinel structure can enhance conductivity while reducing the electrochemical corrosion rate. Ni, Zn (sacrificial anode protection) and Al (anti-oxidation layer) can improve corrosion resistance. The Co element produces solid solution strengthening, hinders dislocation diffusion, and thus improves the performance of the coating.

[0043] Example 2 The difference between this embodiment and embodiment 1 is that: The pre-coating preparation process in step 3 was cancelled, and the composite coating was prepared by synchronous powder feeding using laser cladding technology. The powder feeding rate was 10 g / min, and the other parameters (laser power 1200 W, scanning speed 4 mm / s, spot diameter 3.2 mm, argon flow rate 12 L / min) were consistent with those in Example 1 to obtain a high-entropy oxide ceramic reinforced alloy composite coating.

[0044] Example 3 This embodiment provides a high entropy oxide ceramic reinforced alloy composite coating, and the preparation method thereof comprises the following steps: Step 1: Determine the alloy phase composition as copper, iron, nickel, and aluminum. Weigh the corresponding mass according to Cu 20wt%, Ni 30wt%, Fe 35wt%, and Al15wt%, and the particle size is 200 mesh. Determine the use of CoO, NiO, CuO, and MnO 2 、Al 2 O 3 , Fe 2 O 3 The composition of the high entropy oxide ceramic reinforcement phase is calculated and weighed according to the element molar ratio of Co: Ni: Cu: Mn: Al: Fe = 1:1:1:1:1:10, and the particle size is about 200 mesh; the proportion of high entropy oxide ceramic powder is determined to be 15wt%, and 85g of copper, iron, nickel, and aluminum powder and 15g of high entropy oxide ceramic powder are weighed, and intermittent ball milling is performed for 7h in a planetary ball mill (ball-to-material ratio 2:1, speed 300rpm) to obtain a uniformly distributed mixed raw material powder. The mixed powder is placed in a vacuum drying oven at 80℃ and dried for 7h.

[0045] Step 2: Select Q235 with a size of 100 mm × 100 mm × 10 mm as the substrate for laser cladding, remove impurities on the surface of the substrate by mechanical grinding, place it in a preheating furnace and heat it to 700 °C at 5 °C / min, and keep it warm for 5 hours.

[0046] Step 3: Laser cladding technology was used to prepare the composite coating by synchronous powder feeding. The process parameters were as follows: powder feeding rate 15 g / min, laser power 1200 W, scanning speed 6 mm / s, spot diameter 3 mm, defocus 15 mm, argon flow rate 8 L / min to obtain a high entropy oxide ceramic reinforced alloy composite coating.

[0047] Example 4 This embodiment provides a high entropy oxide ceramic reinforced alloy composite coating, and the preparation method thereof comprises the following steps: Step 1: Determine the alloy phase composition as copper, iron, nickel, and chromium. Weigh the corresponding mass according to Cu 35wt%, Ni 20wt%, Fe 40wt%, and Cr 5wt%, and the particle size is 200 mesh. Determine the use of CoO, NiO, CuO, TiO 2 、Al 2 O 3 , Fe 2 O 3 The composition of the high entropy oxide ceramic reinforcement phase is calculated and weighed according to the element molar ratio of Co: Ni: Cu: Ti: Al: Fe = 1:1:1:1:1:10, and the particle size is about 200 mesh; the proportion of high entropy oxide ceramic powder is determined to be 15wt%, and 85g of copper, iron, nickel and chromium powder and 15g of high entropy oxide ceramic powder are weighed, and intermittent ball milling is performed for 7h in a planetary ball mill (ball-to-material ratio 2:1, speed 280 rpm) to obtain a uniformly distributed mixed raw material powder. The mixed powder is placed in a vacuum drying oven at 80℃ and dried for 7h.

[0048] Step 2: Select Q235 with a size of 100mm×100mm×10mm as the substrate for laser cladding, remove impurities on the surface of the substrate by mechanical grinding, place it in a preheating furnace and heat it to 750℃ at 5℃ / min, and keep it warm for 4h.

[0049] Step 3: Add 4% polyvinyl alcohol solution to the mixed raw material powder obtained in step 1, stir until a uniform paste is formed, and then apply it to the surface of the metal substrate pretreated in step 2. Next, place the coated substrate in a mold and press it under a pressure of 130Mpa to form a pre-coating with a thickness of 1mm. Place the pre-coating in a vacuum drying oven at 80℃ and dry it for 7h. Using laser cladding technology, the pre-coating obtained in step 3 is clad under the process parameters of laser power 2000W, scanning speed 10mm / s, spot diameter 4mm, defocus 15mm, and argon protection flow rate 8L / min to obtain a high entropy oxide ceramic reinforced alloy composite coating.

[0050] Example 5 This embodiment provides a high entropy oxide ceramic reinforced alloy composite coating, and the preparation method thereof comprises the following steps: Step 1: Determine the alloy phase composition as copper, iron and nickel, weigh the corresponding mass according to Cu 20wt%, Ni 40wt%, and Fe 40wt%, and the particle size is 200 mesh. Determine the use of CoO, NiO, CuO, MoO 3 、V 2 O 5, Fe 2 O 3 The composition of the high entropy oxide ceramic reinforcement phase is calculated and weighed according to the element molar ratio Co: Ni: Cu: Mo: V: Fe = 1:1:1:1:1:10, and the particle size is about 200 mesh; the proportion of high entropy oxide ceramic powder is determined to be 40wt%, and 60g of copper iron nickel powder and 40g of high entropy oxide ceramic powder are weighed, and intermittent ball milling is performed for 7h in a planetary ball mill (ball-to-material ratio 2:1, speed 290 rpm) to obtain a uniformly distributed mixed raw material powder. The mixed powder is placed in a vacuum drying oven at 80℃ and dried for 7h.

[0051] Step 2: Select Q235 with a size of 100 mm × 100 mm × 10 mm as the substrate for laser cladding, remove impurities on the surface of the substrate by mechanical grinding, place it in a preheating furnace and heat it to 800 °C at 5 °C / min, and keep it warm for 3 hours.

[0052] Step 3: Add 4% polyvinyl alcohol solution to the mixed raw material powder obtained in step 1, stir until a uniform paste is formed, and then apply it to the surface of the metal substrate pretreated in step 2. Next, place the coated substrate in a mold and press it under a pressure of 100Mpa to form a pre-coating with a thickness of 1mm. The pre-coating was placed in a vacuum drying oven at 80°C and dried for 7h. Laser cladding technology was used to clad the pre-coating obtained in step 3 under the conditions of process parameters of laser power 1500W, scanning speed 6mm / s, spot diameter 3.2mm, defocus 15mm, and argon protection flow rate 20L / min to obtain a high-entropy oxide ceramic reinforced alloy composite coating. Among them, the content of high-entropy ferrite oxide is 46.41wt%.

[0053] Comparative Example 1 Only the alloy phase components in Example 1, namely, Cu 20wt%, Ni 20wt%, Fe 60wt%, and the particle size is 200 mesh. The metal substrate is pretreated in the same manner as in Example 1. The pre-coating preparation process is the same as in Example 1. The process parameters used in laser cladding are consistent with those in Example 1.

[0054] Comparative Example 2 The alloy phase composition of Example 1 is adopted, namely, Cu 20wt%, Ni 20wt%, Fe 60wt%, and the ceramic strengthening phase is NiO and Fe 2 O 3 , weighing the element molar ratio of 1:2, the particle size is 200 mesh, and the ceramic phase ratio is 5wt%. The metal substrate is pretreated in the same manner as in Example 1. The pre-coating preparation process is the same as in Example 1. The laser cladding process parameters are consistent with those in Example 1.

[0055] Application performance testing 1. Coating hardness test Figure 4 The hardness comparison curve of the composite coating of Example 1 and Comparative Example 1 shows that the hardness of the composite coating of Example 1 (5wt% (Co, Ni, Cu, Zn, Al)Fe 2 O 4 The hardness of the coating (ceramic + 95wt% 20Cu-20Ni-60Fe alloy) is increased by 48.01% compared with the coating in comparative example 1 (20Cu-20Ni-60Fe alloy), verifying the positive role of the addition of ceramic phase in improving the mechanical properties of the coating.

[0056] (II) High temperature conductivity test Figure 5 The high temperature conductivity test of the composite coating of Example 1 and Comparative Examples 1 and 2 shows that Example 1 (5wt% (Co, Ni, Cu, Zn, Al) Fe 2 O 4 Ceramic + 95wt% 20Cu-20Ni-60Fe alloy) coating is better than comparative example 2 (5wt% NiFe 2 O 4 +95wt% 20Cu-20Ni-60Fe alloy) coating has an increased conductivity of 48.71% at high temperature, which verifies the advantages of high-entropy ceramic reinforcement phase over conventional nickel-iron spinel ceramic reinforcement phase in conductive properties.

[0057] (III) Molten salt corrosion resistance test The cut samples were placed in molten salt for corrosion by static immersion method. The samples were taken out every hour, cleaned, dried, weighed and the weight changes were recorded. The obtained curve is shown in the figure below. Figure 6 The molten salt corrosion rate of the sample was characterized by the weight loss method, and the corrosion rate of the substrate (Q235) was calculated to be 6.75g / m 2 h, Example 1 (5wt% (Co,Ni,Cu,Zn,Al)Fe 2 O 4 The corrosion rate of the ceramic + 95wt% 20Cu-20Ni-60Fe alloy coating is 1.46g / m 2 h, the corrosion rate of the coating in Comparative Example 1 (20Cu-20Ni-60Fe alloy) is 2.88 g / m 2 ·h, Comparative Example 2 (5wt% NiFe 2 O 4 +95wt% 20Cu-20Ni-60Fe alloy) has a corrosion rate of 2.01g / m 2The corrosion rate of the coating in Example 1 is reduced by about 49.3% compared with that in Comparative Example 1, and is better than that in Comparative Example 2, which verifies that the high entropy oxide ceramic reinforced alloy composite coating has a significant effect in improving the molten salt corrosion resistance.

[0058] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A high entropy oxide ceramic reinforced alloy composite coating, characterized in that: The raw material mixed powder is formed on the substrate surface by laser cladding; The raw material mixed powder comprises 60wt%-95wt% of alloy phase and 5wt%-40wt% of ceramic phase in terms of weight percentage; The alloy phase includes at least three metal elements: Cu, Ni and Fe; The ceramic phase is formed by mixing oxides corresponding to any five metal elements of Co, Ni, Cu, Zn, Al, Mn, Ti, Mo, and V with iron oxide in a molar ratio of the metal elements of 1:1:1:1:1:

10.

2. The high entropy oxide ceramic reinforced alloy composite coating according to claim 1, characterized in that: The raw material mixed powder comprises, by weight percentage, 60wt%-95wt% of the alloy phase and 5wt%-40wt% of the ceramic phase.

3. The high entropy oxide ceramic reinforced alloy composite coating according to claim 1, characterized in that: The composition of the alloy phase, by weight percentage, is 20wt%-35wt% for Cu, 20wt%-40wt% for Ni, and 35wt%-60wt% for Fe.

4. The high entropy oxide ceramic reinforced alloy composite coating according to claim 3, characterized in that: The alloy phase also includes Cr and / or Al elements, and the addition amount of Cr and / or Al is 0.01wt%-15wt%.

5. The high entropy oxide ceramic reinforced alloy composite coating according to claim 1, characterized in that: In the high entropy oxide ceramic reinforced alloy composite coating, the content of high entropy ferrite oxide is 4.24wt%-46.41wt%.

6. A method for preparing a high entropy oxide ceramic reinforced alloy composite coating according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, weighing and mixing raw materials according to the proportion of each component, and subjecting the raw materials to ball milling and drying to obtain raw material mixed powder; S2, performing surface treatment and preheating on the substrate to obtain a cladding substrate; S3. Laser cladding the surface of the cladding substrate using the raw material mixed powder by synchronous powder feeding; or first forming a pre-coating on the surface of the cladding substrate with the raw material mixed powder, and then laser cladding the pre-coating to obtain a high entropy oxide ceramic reinforced alloy composite coating.

7. The preparation method according to claim 6, characterized in that: In step S3, the parameters of the laser cladding include: laser power of 1200-2000 W, scanning speed of 4-10 mm / s, defocusing amount of 10-15 mm, and spot diameter of 3-4 mm.

8. The preparation method according to claim 6, characterized in that: In step S3, the synchronous powder feeding speed is 10-15 g / min.

9. The preparation method according to claim 6, characterized in that: In step S3, the preparation method of the pre-coating layer is as follows: the raw material mixed powder is blended with a binder to form a paste mixture, the paste mixture is applied to the surface of the cladding substrate, and the pre-coating layer is obtained by pressing and drying.

10. Use of the high entropy oxide ceramic reinforced alloy composite coating according to any one of claims 1 to 5 or the high entropy oxide ceramic reinforced alloy composite coating prepared by the preparation method according to any one of claims 6 to 9 in the protection of inert anodes for electrolytic aluminum.

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