A preparation method of a medium-entropy or high-entropy alloy cladding layer

Abstract

This invention belongs to the field of alloy coating preparation technology, specifically relating to a method for preparing a medium-entropy or high-entropy alloy cladding layer. The invention involves mixing at least three elemental metal powders to obtain a mixed metal powder; depositing the mixed metal powder on a substrate surface to obtain a mixed metal powder layer; and performing radio frequency plasma cladding on the mixed metal powder layer using mixed plasma to obtain a medium-entropy or high-entropy radio frequency plasma cladding layer. The mixed plasma includes inert gas plasma and water vapor plasma. This invention utilizes water vapor plasma to assist inert gas plasma, and simultaneously leverages the high-temperature effect of radio frequency plasma to achieve rapid in-situ preparation of a medium-entropy or high-entropy radio frequency plasma cladding layer. Furthermore, the medium-entropy or high-entropy alloy cladding layer obtained with the assistance of water vapor plasma exhibits characteristics of low porosity, uniform microstructure, and high density.

Description

Technical Field

[0001] This invention belongs to the field of alloy coating preparation technology, specifically relating to a method for preparing a medium-entropy or high-entropy alloy cladding layer. Background Technology

[0002] Medium-entropy and high-entropy alloys are concentrated solid solution alloys composed of three, four, or more metallic elements in equimolar or near-equimolar ratios. Due to their excellent mechanical and physicochemical properties, such as high strength, high hardness, high wear resistance, and high corrosion resistance, they hold promise as important advanced coating materials. However, the preparation of high-performance medium-entropy / high-entropy alloy coatings is quite difficult. Currently, there is an urgent need for technologies that can significantly improve the preparation efficiency of these coatings to accelerate the experimental research and engineering applications of high-performance medium-entropy / high-entropy alloy coatings. Therefore, many researchers are attempting to optimize coating preparation methods to improve the preparation efficiency of these alloy coatings.

[0003] Currently, there are two main methods for preparing medium-entropy / high-entropy alloy coatings: laser cladding and plasma cladding. Among them, laser cladding for preparing high-entropy alloy coatings has been the most widely studied. However, medium-entropy / high-entropy alloy coatings prepared by laser cladding have problems such as uneven microstructure and easy formation of pores and inclusions. Moreover, the size of the high-energy laser beam is in the micrometer range, which results in low cladding efficiency for large-area alloy coatings.

[0004] Plasma cladding technology, developed from thermal spraying, is an emerging coating preparation technology with significant advantages in the preparation of medium-entropy / high-entropy alloy coatings. While direct current plasma can achieve rapid and efficient preparation of these alloy coatings, excessively high cladding temperatures can cause the anode material to melt, contaminating the medium-entropy or high-entropy alloy coating. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a medium-entropy or high-entropy alloy cladding layer. The preparation method provided by this invention is highly efficient, and the obtained medium-entropy or high-entropy alloy cladding layer has the characteristics of low porosity, uniform microstructure, high density and low impurity content.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing a medium-entropy or high-entropy alloy cladding layer, comprising the following steps:

[0008] Mixing at least three elemental metal powders yields a mixed metal powder.

[0009] A mixed metal powder layer is obtained by distributing mixed metal powder on the surface of a substrate.

[0010] A mixed plasma is generated using radio frequency (RF) and then the mixed plasma is used to perform RF plasma cladding on the mixed metal powder layer to obtain a medium-entropy or high-entropy alloy cladding layer. The mixed plasma includes inert gas plasma and water vapor plasma.

[0011] Preferably, the method for generating hybrid plasma using radio frequency includes the following steps:

[0012] A dual-channel torch tube and a radio frequency generator disposed on the outer periphery of the dual-channel torch tube are provided. The dual-channel torch tube includes a central channel and a peripheral channel arranged in concentric circles.

[0013] Atomized water and a first inert gas are introduced into the central channel, while a second inert gas is introduced into the outer channel.

[0014] An inert gas plasma is obtained by ionizing the second inert gas in the peripheral channel using a radio frequency generator.

[0015] Near the outlet of the dual-channel torch, the inert gas plasma ejected from the outer channel plasma vaporizes the atomized water ejected from the central channel and the first inert gas plasma, resulting in a mixed plasma.

[0016] Preferably, the first inert gas is argon; the flow rate of the first inert gas is 0.4 to 0.5 L / min.

[0017] Preferably, the second inert gas is argon; the flow rate of the second inert gas is 10-12 L / min.

[0018] Preferably, the droplet diameter of the atomized water is ≤5μm; the flow rate is 0.1~0.3mL / min.

[0019] Preferably, the operating power of the radio frequency generator is 900-1000W.

[0020] Preferably, the particle size of the elemental metal powder is ≤50μm.

[0021] Preferably, the thickness of the mixed metal powder layer is 1 to 3 mm.

[0022] Preferably, the vertical distance between the mixed plasma and the surface of the mixed metal powder layer is 8 to 15 mm.

[0023] Preferably, the relative velocity between the mixed plasma and the mixed metal powder layer is 0.1 to 0.5 mL / min.

[0024] This invention provides a method for preparing a medium-entropy or high-entropy alloy cladding layer, comprising the following steps: mixing at least three elemental metal powders to obtain a mixed metal powder; depositing the mixed metal powder on a substrate surface to obtain a mixed metal powder layer; generating a mixed plasma using radio frequency (RF) and then performing RF plasma cladding on the mixed metal powder layer to obtain a medium-entropy or high-entropy alloy cladding layer, wherein the mixed plasma includes inert gas plasma and water vapor plasma. This invention utilizes the high enthalpy and high chemical reactivity of water vapor plasma, combined with the assistance of inert gas plasma, and the high-temperature effect of RF plasma, to achieve rapid in-situ preparation of the medium-entropy or high-entropy alloy cladding layer. Furthermore, the medium-entropy or high-entropy alloy cladding layer obtained with the assistance of water vapor plasma exhibits low porosity, uniform microstructure, and high density. Moreover, because this invention uses RF plasma as the heat source for cladding the mixed metal powder, the heating method greatly avoids the influence of electrode melting on the coating purity, resulting in a medium-entropy or high-entropy alloy cladding layer with low impurity content. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the apparatus used in the rapid preparation method of spray-assisted medium-entropy / high-entropy radio frequency plasma cladding layer of the present invention;

[0026] Figure 1 In the middle: 1 is a water mist generator, 2 is a flow meter, 3 is a radio frequency generator, 4 is a gas cylinder, 5 is a torch tube, 6 is a three-axis moving platform, and 7 is a cooling circulation machine;

[0027] Figure 2 This is a preparation roadmap for the rapid preparation method of spray-assisted medium-entropy / high-entropy radio frequency plasma cladding layer of the present invention;

[0028] Figure 3 This is a metallurgical bonding diagram of the CuFeNi medium-entropy alloy cladding coating in Example 1;

[0029] Figure 4 The image shows the BSE diagram of the CuFeNi medium-entropy alloy cladding coating in Example 1.

[0030] Figure 5 The image shows the BSE pattern of the FeCoNiCuAl high-entropy alloy cladding coating in Example 2.

[0031] Figure 6 An optical photograph of the CuFeNi medium-entropy alloy cladding coating prepared for Comparative Example 1. Detailed Implementation

[0032] This invention provides a method for preparing a medium-entropy or high-entropy alloy cladding layer, comprising the following steps:

[0033] Mixing at least three elemental metal powders yields a mixed metal powder.

[0034] A mixed metal powder layer is obtained by distributing mixed metal powder on the surface of a substrate.

[0035] A mixed plasma is generated using radio frequency (RF) and then the mixed plasma is used to perform RF plasma cladding on the mixed metal powder layer to obtain a medium-entropy or high-entropy alloy cladding layer. The mixed plasma includes inert gas plasma and water vapor plasma.

[0036] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0037] The present invention mixes at least three elemental metal powders to obtain mixed metal powder.

[0038] In this invention, the particle size of the elemental metal powder is preferably ≤50μm, and more preferably 10~50μm.

[0039] In this invention, the purity of the elemental metal powder is preferably ≥99.99%.

[0040] In this invention, the elemental metal powder preferably includes at least three of Al, Ti, Cu, Fe, Co, Cr and Ni; specifically, it is preferably Cu, Fe and Ni, or Al, Cu, Fe, Co and Ni.

[0041] In specific embodiments of the present invention, the elemental metal powders used to prepare the medium-entropy alloy cladding layer are preferably Cu, Fe, and Ni. The elemental metal powders used to prepare the high-entropy alloy cladding layer are preferably Al, Cu, Fe, Co, and Ni.

[0042] In this invention, during the mixing process, the elemental metal powders are mixed in an equiatomic or near-equiatomic ratio.

[0043] In a preferred embodiment of the present invention, the mixing is preferably mechanical mixing, preferably carried out in a powder mixer, the mixing speed is preferably 80-100 r / min, more preferably 80 r / min; the mixing time is preferably ≥30 min, to ensure that the elemental metal powder is mixed uniformly.

[0044] After obtaining the mixed metal powder, the present invention distributes the mixed metal powder on the surface of the substrate to obtain a mixed metal powder layer.

[0045] In this invention, the substrate is preferably made of low-carbon steel. Pre-treatment of the substrate is preferred. Pre-treatment preferably includes: sequentially grinding, washing, and drying the surface of the substrate. Grinding is preferably performed using sandpaper. Washing is preferably performed by immersing the ground substrate in an organic solvent for ultrasonic cleaning; the organic solvent is preferably anhydrous ethanol. Drying is preferably performed in a dryer.

[0046] The present invention does not have any special requirements for the specific implementation of the arrangement; the mixed metal powder can simply be spread evenly on the surface of the substrate.

[0047] In this invention, the thickness of the mixed metal powder layer is preferably 1 to 3 mm, and more preferably 2 mm.

[0048] In a specific embodiment of the present invention, the size of the mixed metal powder layer is preferably 20mm × 5mm × 2mm.

[0049] After obtaining the mixed metal powder layer, the present invention uses radio frequency to generate mixed plasma, and then uses the mixed plasma to perform radio frequency plasma cladding on the mixed metal powder layer to obtain a medium-entropy or high-entropy alloy cladding layer. The mixed plasma includes inert gas plasma and water vapor plasma.

[0050] In this invention, the method for generating hybrid plasma using radio frequency preferably includes the following steps:

[0051] A dual-channel torch tube and a radio frequency generator disposed on the outer periphery of the dual-channel torch tube are provided. The dual-channel torch tube includes a central channel and a peripheral channel arranged in concentric circles.

[0052] Atomized water and a first inert gas are introduced into the central channel, while a second inert gas is introduced into the outer channel.

[0053] An inert gas plasma is obtained by ionizing the second inert gas in the peripheral channel using an activated radio frequency generator.

[0054] Near the outlet of the dual-channel torch, the inert gas plasma ejected from the outer channel plasma vaporizes the atomized water ejected from the central channel and the first inert gas plasma, resulting in a mixed plasma.

[0055] This invention provides a dual-channel torch and a radio frequency generator disposed on the outer periphery of the dual-channel torch. The dual-channel torch includes a central channel and a peripheral channel arranged in concentric circles. In this invention, the dual-channel torch and the radio frequency generator can be equipment components well known to those skilled in the art.

[0056] The present invention introduces atomized water and a first inert gas into the central channel, and simultaneously introduces a second inert gas into the outer channel.

[0057] In this invention, the atomized water is preferably atomized distilled water. The droplet diameter of the atomized water is preferably ≤5μm, more preferably 1-5μm; the flow rate of the atomized water entering the central channel is preferably 0.1-0.3mL / min, more preferably 0.3mL / min. In this invention, the atomized water is preferably generated by a water mist generator.

[0058] In this invention, the first inert gas is argon; the flow rate of the first inert gas is preferably 0.4 to 0.5 L / min, more preferably 0.42 to 0.46 L / min.

[0059] In this invention, the central channel of the dual-channel torch is filled with atomized water and a first inert gas. The first inert gas serves as the carrier gas for the atomized water, carrying it through the dual-channel torch and mixing it with the inert gas plasma formed in the outer channel. Simultaneously, the atomized water is plasma-ionized by the inert gas plasma formed in the outer channel, resulting in water vapor plasmaization. At the same time, the first inert gas is also plasma-ionized by the inert gas plasma formed in the outer channel, forming inert gas plasma.

[0060] In this invention, the second inert gas is argon; the flow rate of the second inert gas is preferably 10-12 L / min, more preferably 10.5-11.5 L / min.

[0061] In the preparation method provided by this invention, the flow rate of the second inert gas cannot be too high or too low. If the flow rate of the second inert gas is too high, it cannot be fully ionized by the radio frequency generator to form inert gas plasma. If the flow rate of the second inert gas is too low, the formed inert gas plasma cannot fully plasmaize the atomized water and the first inert gas, resulting in water vapor plasma and inert gas plasma. This leads to a low water vapor plasma content, low temperature, and low chemical activity in the mixed plasma, making the formed medium-entropy / high-entropy alloy cladding layer prone to pore formation, incomplete reaction of the elemental metal powder, and uneven microstructure.

[0062] Meanwhile, the preparation method provided by the present invention, by controlling the droplet diameter and flow rate of the atomized water, the flow rate of the first inert gas, and the flow rate of the second inert gas in coordination, realizes the inert gas plasma formed by the ionization of the second inert gas under the action of the radio frequency generator. The atomized water and the first inert gas are fully mixed and plasmaized near the outlet of the dual-channel torch, resulting in a mixed plasma with high chemical activity and high temperature. This provides a guarantee for the preparation of an entropy or high-entropy radio frequency plasma cladding layer with low porosity, uniform structure, high density and low impurity content.

[0063] This invention employs a radio frequency generator to ionize a second inert gas within a peripheral channel to obtain inert gas plasma. In this invention, the operating power of the radio frequency generator is preferably 900–1000 W, more preferably 900 W.

[0064] In this invention, near the outlet of the dual-channel torch, the inert gas plasma ejected from the outer channel plasma plasmas the atomized water ejected from the central channel plasma and the first inert gas plasma plasma to obtain a mixed plasma.

[0065] In this invention, a substrate with a mixed metal powder layer on its surface is preferably placed on a three-axis moving platform for radio frequency plasma cladding. During the radio frequency plasma cladding process, this invention preferably uses a cooling medium to cool the substrate.

[0066] In this invention, the vertical distance between the mixed plasma and the surface of the mixed metal powder layer is preferably 8-10 mm, more preferably 10 mm. This vertical distance ensures that the mixed powder can be fully melted to form a coating.

[0067] In this invention, the relative motion speed between the mixed plasma and the mixed metal powder layer is preferably 0.1–0.5 mL / min, more preferably 0.3 mL / min. This invention preferably utilizes the three-axis moving platform driven by a motor to achieve translational motion in the XYZ directions, thereby realizing the relative motion between the mixed plasma and the mixed metal powder layer.

[0068] After obtaining the medium-entropy or high-entropy alloy cladding layer, the present invention preferably cools the medium-entropy or high-entropy alloy cladding layer to room temperature in a protective gas atmosphere. The protective gas is preferably an inert gas, more preferably argon. In a specific embodiment of the present invention, the present invention preferably continues to supply a second inert gas to the medium-entropy or high-entropy alloy cladding layer through the peripheral channel of the dual-channel torch to form a protective gas atmosphere.

[0069] In a specific embodiment of the present invention, the radio frequency plasma cladding preferably employs, as shown in the following... Figure 1 The radio frequency plasma cladding apparatus shown is used for this process. The following is in conjunction with... Figure 1 The radio frequency plasma cladding apparatus used in this invention will be described in detail.

[0070] The radio frequency plasma cladding device provided by this invention includes a torch 5, which is a dual-channel torch comprising a central channel and an outer channel arranged concentrically. In a specific embodiment of this invention, the central channel of the dual-channel torch is vented with atomized water and a first inert gas (the first inert gas being the central gas in this embodiment), and the outer channel of the dual-channel torch is vented with a second inert gas (the first inert gas being the outer gas in this embodiment). The first inert gas serves as a carrier for the atomized water, carrying it through the torch 5 and mixing it with the inert gas plasma formed in the outer channel. The atomized water is plasma-purified by the inert gas plasma formed in the outer channel, ultimately generating water vapor plasma.

[0071] The radio frequency plasma cladding device provided by the present invention includes a water mist generator 1, wherein the atomization outlet of the water mist generator 1 is connected to the gas inlet of the central channel of the torch tube 5. In the present invention, the water mist generator 1 is used to generate atomized water.

[0072] The radio frequency plasma cladding apparatus provided by this invention includes a three-axis moving platform 6. The three-axis moving platform 6 is located below the torch tube 5. The three-axis moving platform 6 is used to place a substrate with a mixed metal powder layer on its surface, and radio frequency plasma cladding is performed under the action of the mixed plasma formed near the outlet of the torch tube 5 to obtain a medium-entropy or high-entropy radio frequency plasma cladding layer.

[0073] In this invention, the three-axis moving platform 6 can achieve XYZ three-degree-of-freedom translation under the drive of the motor.

[0074] As one or more embodiments of the present invention, the three-axis moving platform 6 is provided with a cooling medium channel inside, and when a cooling medium is introduced into the cooling medium channel, it is used to cool the substrate.

[0075] The radio frequency plasma cladding apparatus provided by this invention includes a cooling circulation machine 7. The cooling circulation machine 7 is connected to the inlet and outlet of the cooling medium channel of the three-axis moving platform 6.

[0076] The radio frequency plasma cladding device provided by the present invention includes a gas cylinder 4. The gas cylinder 4 is used to store inert gas.

[0077] In this invention, the gas cylinder 4 is connected to both the central channel and the peripheral channel of the torch. Flow meters 2 are installed on the pipelines connecting the gas cylinder 4 to the central channel and the peripheral channel of the torch.

[0078] This invention provides a rapid preparation method for spray-assisted medium-entropy / high-entropy radio frequency plasma cladding layers. Utilizing the high-temperature effect of radio frequency plasma and the high enthalpy of water vapor plasma, this invention achieves in-situ preparation of complex medium-entropy and high-entropy alloys. The preparation method specifically includes: substrate pretreatment; powder mixing; radio frequency plasma preparation; and cladding coating preparation. In the plasma preparation step for high-entropy alloys, both the peripheral gas introduced into the outer channel of the torch and the central gas introduced into the central channel are argon. Plasma is generated by ionizing the argon gas using a radio frequency generator. The spray droplets are distilled water, which, under the entrainment of the peripheral gas, mixes with the inert gas plasma formed by the central gas near the torch outlet. The spray-doped plasma can form a mixture of inert gas plasma and water vapor plasma, thereby forming a higher-temperature plasma flame that rapidly melts the mixed metal powder spread on the substrate, ultimately forming a cladding coating. This invention enables rapid in-situ cladding preparation of alloy coatings, forming a dense medium-entropy / high-entropy coating structure, greatly improving the cladding efficiency of alloy coatings. The present invention features a rationally arranged process and is simple to implement. It can be used to prepare various types of medium-entropy / high-entropy alloy coatings, significantly improving the coating preparation efficiency. The prepared medium-entropy / high-entropy alloy coatings have low porosity and uniform microstructure.

[0079] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0080] Example 1

[0081] The rapid preparation method for spray-assisted CuFeNi medium-entropy alloy radio frequency plasma cladding layer described in this embodiment adopts... Figure 1 The preparation apparatus shown is prepared according to Figure 2 The preparation process shown includes the following steps:

[0082] (a) Substrate pretreatment: First, cut the low-carbon steel into 60mm×20mm×5mm plates; then use sandpaper to polish the surface of the low-carbon steel to remove the oxide layer until the metallic luster is exposed; next, immerse the polished substrate in anhydrous ethanol for ultrasonic cleaning; finally, place the cleaned substrate in a dryer to dry, obtaining the pretreated substrate. Mount the substrate on a three-axis moving platform;

[0083] (b) Powder mixing: Weigh Cu, Fe, Ni, and elemental metal powders with a purity of 99.99% and a particle size of 50 μm according to their equiatomic ratio and place them in a medicine bottle. Place the medicine bottle horizontally in a powder mixer and mechanically mix at a speed of 80 r / min for 30 min to ensure that the mixed powder is thoroughly shaken in the powder mixer. Use a sample spoon to take out 5 g of the shaken powder and spread it evenly on the substrate treated in step (a) to form a mixed powder layer of 20 mm × 5 mm × 2 mm.

[0084] (c) Radio Frequency Plasma Preparation: Adjust the flow rates of the peripheral and central gases. Argon is used for the central gas, peripheral gas, and protective gas during subsequent cooling. Argon flow rate is controlled by a flow meter, with the central gas flow rate at 0.4 L / min and the peripheral gas flow rate at 10 L / min. Turn on the water chiller and the radio frequency generator (900W) to ignite the radio frequency plasma. Atomize distilled water using a water mist generator to achieve droplet diameters of 5 μm. The flow rate of the atomized distilled water is controlled by a flow meter at 0.3 mL / min. Mix the atomized distilled water with the central gas and then spray it out.

[0085] (d) Preparation of cladding coating: The motor drives the three-axis moving platform to translate along the XYZ directions, moving the mixed powder layer laid on the substrate to below the radio frequency plasma, ensuring that the working distance between the radio frequency plasma and the mixed powder is 10 mm, so as to realize the radio frequency plasma cladding preparation of CuFeNi medium entropy alloy coating. The working time of radio frequency plasma is 10 seconds to ensure that the mixed powder is completely melted and clad on the substrate surface. The power supply of the radio frequency generator and the water mist generator is turned off, and the argon gas is continued to be supplied to the surrounding gas, so that the alloy melt is cooled in the argon environment for 20 seconds, and the substrate with CuFeNi medium entropy alloy cladding coating is obtained.

[0086] according to Figure 3 The metallurgical bonding images of the coating show that the CuFeNi medium-entropy alloy cladding coating exhibits a metallurgical bond with the substrate, and the bonding surface is dense. According to... Figure 4 BSE micrographs of the coating show that the CuFeNi medium-entropy alloy cladding coating has low internal porosity and uniform grain size.

[0087] Example 2

[0088] The rapid preparation method for spray-assisted FeCoNiCuAl high-entropy alloy radio frequency plasma cladding layer described in this embodiment adopts... Figure 1 The preparation apparatus shown is prepared according to Figure 2 The preparation process shown includes the following steps:

[0089] (a) Substrate pretreatment: First, the low-carbon steel is cut into 60×20×5mm plates; then, the surface of the low-carbon steel is polished with sandpaper to remove the oxide layer until the metallic luster is exposed; next, the polished substrate is immersed in anhydrous ethanol for ultrasonic cleaning; finally, the cleaned substrate is placed in a dryer to dry, obtaining the pretreated substrate. The substrate is then mounted on a three-axis moving platform;

[0090] (b) Powder mixing: Fe, Co, Ni, Cu, and Al elemental metal powders with a purity of 99.99% and a particle size of 50 μm were weighed according to their equiatomic ratio and placed in medicine bottles. The medicine bottles were placed horizontally in a powder mixer and mechanically mixed at a speed of 80 r / min for 30 min to ensure that the mixed powder was thoroughly shaken in the powder mixer. Using a sample spoon, 6 g of the shaken powder was taken out and spread evenly on the substrate treated in step (a) to form a mixed powder layer of 20 mm × 5 mm × 2 mm.

[0091] (c) Radio Frequency Plasma Preparation: Adjust the flow rates of the peripheral and central gases. The central gas, peripheral gas, and protective gas used in the subsequent cooling process are all argon. Argon gas flow rate is controlled by a flow meter, with the central gas flow rate at 0.5 L / min and the peripheral gas flow rate at 10 L / min. Turn on the water chiller and the radio frequency power supply to ignite the radio frequency plasma. The radio frequency plasma power is 900 W. Distilled water is atomized using a water mist generator to achieve a droplet diameter of 5 μm. The flow rate of the atomized distilled water is controlled by a flow meter at 0.3 mL / min. The atomized distilled water is mixed with the central gas and then sprayed out.

[0092] (d) Preparation of cladding coating: The motor drives the three-axis moving platform to translate along the XYZ directions, moving the mixed powder layer laid on the substrate to below the radio frequency plasma. The working distance between the radio frequency plasma and the mixed powder is 10 mm to ensure that the mixed powder can melt and fuse quickly, thus realizing the radio frequency plasma cladding preparation of FeCoNiCuAl high-entropy alloy coating. The working time of the radio frequency plasma is 10 seconds to ensure that the mixed powder is completely melted and clad on the substrate surface. The power of the radio frequency generator and the water mist generator is turned off, and the argon gas is continued to be supplied to the surrounding gas, so that the alloy melt is cooled in the argon environment for 20 seconds, thus obtaining the substrate with FeCoNiCuAl high-entropy alloy cladding coating.

[0093] according to Figure 5 BSE micrographs of the coating show that the FeCoNiCuAl high-entropy alloy cladding coating has low internal porosity and uniform grain size.

[0094] Comparative Example 1

[0095] The rapid preparation method of spray-assisted CuFeNi medium-entropy alloy radio frequency plasma cladding layer described in this comparative example adopts... Figure 1 The preparation apparatus shown specifically includes the following steps:

[0096] (a) Substrate pretreatment: First, cut the low-carbon steel into 60mm×20mm×5mm plates; then use sandpaper to polish the surface of the low-carbon steel to remove the oxide layer until the metallic luster is exposed; next, immerse the polished substrate in anhydrous ethanol for ultrasonic cleaning; finally, place the cleaned substrate in a dryer to dry, obtaining the pretreated substrate. Mount the substrate on a three-axis moving platform;

[0097] (b) Powder mixing: Weigh Cu, Fe, Ni, and elemental metal powders with a purity of 99.99% and a particle size of 50 μm according to their equiatomic ratio and place them in a medicine bottle. Place the medicine bottle horizontally in a powder mixer and mechanically mix at a speed of 80 r / min for 30 min to ensure that the mixed powder is thoroughly shaken in the powder mixer. Use a sample spoon to take out 5 g of the shaken powder and spread it evenly on the substrate treated in step (a) to form a mixed powder layer of 20 mm × 5 mm × 2 mm.

[0098] (c) Radio Frequency Plasma Preparation: Adjust the flow rates of the peripheral and central gases. The central gas, peripheral gas, and protective gas used in the subsequent cooling process are all argon. Argon gas flow rate is controlled by a flow meter, with the central gas flow rate at 0.4 L / min and the peripheral gas flow rate at 10 L / min. Turn on the water chiller and activate the radio frequency generator (900W) to ignite the radio frequency plasma. The central gas is ejected separately.

[0099] (d) Preparation of cladding coating: The motor drives the three-axis moving platform to translate along the XYZ directions, moving the mixed powder layer laid on the substrate to below the radio frequency plasma, ensuring that the working distance between the radio frequency plasma and the mixed powder is 10 mm, so as to realize the radio frequency plasma cladding preparation of CuFeNi medium entropy alloy coating. The working time of radio frequency plasma is 10 seconds to ensure that the mixed powder is completely melted and clad on the substrate surface. The power supply of the radio frequency generator and the water mist generator is turned off, and the argon gas is continued to be supplied to the surrounding gas, so that the alloy melt is cooled in the argon environment for 20 seconds, and the substrate with CuFeNi medium entropy alloy cladding coating is obtained.

[0100] according to Figure 6 As can be seen from the optical photographs of the coating, compared with the preparation method provided in Example 1, the CuFeNi medium-entropy alloy coating of Comparative Example 1 without spray assistance contains a large number of pores and unmelted metal powder, and the performance of the prepared CuFeNi medium-entropy alloy coating is worse than that of Example 1.

[0101] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a medium-entropy or high-entropy alloy cladding layer, characterized in that, Includes the following steps: Mixing at least three elemental metal powders yields a mixed metal powder. A mixed metal powder layer is obtained by distributing mixed metal powder on the surface of a substrate. A mixed plasma is generated using radio frequency (RF) and then the mixed plasma is used to perform RF plasma cladding on the mixed metal powder layer to obtain a medium-entropy or high-entropy alloy cladding layer. The mixed plasma includes inert gas plasma and water vapor plasma.

2. The preparation method according to claim 1, characterized in that, The method for generating hybrid plasma using radio frequency includes the following steps: A dual-channel torch tube and a radio frequency generator disposed on the outer periphery of the dual-channel torch tube are provided. The dual-channel torch tube includes a central channel and a peripheral channel arranged in concentric circles. Atomized water and a first inert gas are introduced into the central channel, while a second inert gas is introduced into the outer channel. An inert gas plasma is obtained by ionizing the second inert gas in the peripheral channel using a radio frequency generator. Near the outlet of the dual-channel torch, the inert gas plasma ejected from the outer channel plasma vaporizes the atomized water ejected from the central channel and the first inert gas plasma, resulting in a mixed plasma.

3. The preparation method according to claim 2, characterized in that, The first inert gas is argon; the flow rate of the first inert gas is 0.4 to 0.5 L / min.

4. The preparation method according to claim 2 or 3, characterized in that, The second inert gas is argon; the flow rate of the second inert gas is 10-12 L / min.

5. The preparation method according to claim 2 or 3, characterized in that, The droplet diameter of the atomized water is ≤5μm; the flow rate is 0.1~0.3mL / min.

6. The preparation method according to claim 2, characterized in that, The operating power of the radio frequency generator is 900-1000W.

7. The preparation method according to claim 1, characterized in that, The particle size of the elemental metal powder is ≤50μm.

8. The preparation method according to claim 1, characterized in that, The thickness of the mixed metal powder layer is 1 to 3 mm.

9. The preparation method according to claim 1 or 8, characterized in that, The vertical distance between the mixed plasma and the surface of the mixed metal powder layer is 8–15 mm.

10. The preparation method according to claim 1, characterized in that, The relative velocity between the mixed plasma and the mixed metal powder layer is 0.1–0.5 mL / min.

Images