A high-entropy alloy coating and a method of making the same

Abstract

This invention discloses a high-entropy alloy coating and its preparation method, belonging to the field of protective coating preparation technology. The preparation method of the high-entropy alloy coating of this invention includes the following steps: mixing elemental powders of Al, Co, Cr, Fe, Mo, Ni, Ti, and Cu to obtain cladding raw material powder; wherein the molar ratio of Al, Co, Cr, Fe, Mo, Ni, Ti, and Cu elemental powders is 1:1:1:1:1:1:1:0.25-1; and preparing a high-entropy alloy coating by cladding the cladding raw material powder onto the surface of a substrate. This invention uses traditional carbon steel as the substrate, employs a simple mechanical ball milling method to prepare the cladding raw material powder, and utilizes a coaxial powder feeding high-speed laser cladding device to efficiently prepare AlCoCrFeMoNiTiCu coatings with adjustable thickness. x The single-phase high-entropy alloy coating has high hardness and exhibits excellent corrosion resistance and gas-liquid erosion resistance. It can be used as a surface protective coating for downhole tubing and surface pipeline steel in the oil and gas industry.

Description

Technical Field

[0001] This invention relates to the field of protective coating preparation technology, specifically to a high-entropy alloy coating and its preparation method. Background Technology

[0002] In oil and gas exploration and development operations, pipeline engineering is an indispensable facility in oil and gas fields and a key to transportation. Currently, oil and gas exploration and development is moving towards "ultra-deep, low-temperature, low-volume, marine, and unconventional" directions, leading to increasingly complex and demanding service environments for oil pipelines. Corrosion-induced failures not only cause huge economic losses but also lead to ecological damage and threaten public safety. Furthermore, the wear and erosion accompanying corrosion conditions further exacerbate the frequency and consequences of failures, placing higher demands on pipeline material selection. Traditional oil pipelines are mostly made of ordinary carbon steel, with a small amount of 13Cr and 316L stainless steel. Currently, in conditions with high sulfur and carbon dioxide content, the use of iron-nickel-based and nickel-based alloys is gradually increasing. While these corrosion-resistant alloys possess excellent corrosion resistance, their high price and poor machinability hinder their widespread application. Therefore, judging from the research situation at home and abroad, preparing high-performance protective coatings on low-cost carbon steel pipe substrates to meet the harsh service environment under the coupled conditions of corrosion, wear, and erosion is an inevitable trend to promote the economical, long-term and safe service of pipelines.

[0003] Currently, epoxy powder coatings are widely used on oil pipelines. While these coatings offer good corrosion resistance, their poor high-temperature resistance, weak adhesion, and insufficient wear resistance severely limit their application prospects in harsh operating conditions. Therefore, seeking a metallic material that provides high corrosion resistance and strong wear resistance in harsh oil and gas service environments, and selecting appropriate preparation techniques to achieve a coating with sufficient thickness and good bonding with the substrate, is fundamental to promoting the practical application of high-performance coating technology on oil and gas pipelines. In recent years, high-entropy alloys have rapidly become one of the research hotspots in the field of engineering materials both domestically and internationally due to their unique alloy phase structure and excellent comprehensive performance. Compared to bulk high-entropy alloys, preparing high-entropy alloy coatings can achieve excellent performance while reducing the amount of precious metal materials used, thus saving costs. Currently, common preparation methods for high-entropy alloy coatings include laser cladding, vapor deposition, and magnetron sputtering. Among these, laser cladding produces coatings with a high-strength metallurgical bond to the substrate, resulting in a fine and dense structure that is beneficial for coating performance. Building on this, the emerging ultra-high-speed laser cladding technology has broken through the low efficiency of traditional cladding, with a cladding speed of up to 200m / min, achieving better surface quality and lower dilution rate, and showing significant prospects for industrial applications.

[0004] AlCoCrFeNi 2.1The alloy is a typical eutectic high-entropy alloy, possessing excellent comprehensive mechanical properties and corrosion resistance, making it suitable for high-speed laser cladding technology. However, AlCoCrFeNi 2.1 High-entropy alloys have low hardness, resulting in poor wear resistance and erosion resistance. Even with adjustments using Al elements, their properties remain unsatisfactory (AlCoCrFeNi). 2.1 The ratio of BCC to FCC in high entropy alloys is used to increase hardness, but the hardness is still relatively low. For example, patent CN115287652A discloses an erosion-resistant and cavitation-resistant high entropy alloy-based coating and its preparation method. Specifically, it discloses a nickel-coated high entropy alloy coating reinforced with multiple nano-alumina particles, but the high entropy alloy coating prepared by this patent has low hardness. Summary of the Invention

[0005] The purpose of this invention is to provide a high-entropy alloy coating and its preparation method, which solves the technical problems of poor high-temperature and corrosion resistance, insufficient wear resistance, and poor adhesion of existing oil pipeline coatings.

[0006] To achieve the above objectives, one embodiment of the present invention provides a method for preparing a high-entropy alloy coating, comprising the following steps:

[0007] The powders of elemental elements Al, Co, Cr, Fe, Mo, Ni, Ti and Cu are mixed to obtain the cladding raw material powder; wherein the molar ratio of elemental elemental powders of Al, Co, Cr, Fe, Mo, Ni, Ti and Cu is 1:1:1:1:1:1:1:0.25-1;

[0008] A high-entropy alloy coating is prepared by cladding raw material powder onto the surface of a substrate.

[0009] In one preferred embodiment of the present invention, the cladding process parameters are as follows: laser cladding power of 1kW-2.5kW, laser scanning rate of 3000mm / min-10000mm / min, and cladding overlap rate of 60%-90%.

[0010] One preferred embodiment of the present invention involves mixing elemental powders of Al, Co, Cr, Fe, Mo, Ni, Ti, and Cu to obtain cladding raw material powder, comprising: mixing elemental powders of Al, Co, Cr, Fe, Mo, Ni, Ti, and Cu and ball milling them to obtain cladding raw material powder.

[0011] In one preferred embodiment of the present invention, the particle size of the elemental powder is 53μm-105μm.

[0012] In one preferred embodiment of the present invention, the ball-to-material ratio of the ball mill is 3-10:1, the ball milling speed is 100r / min-300r / min, and the ball milling time is 3h-12h.

[0013] In one preferred embodiment of the present invention, argon gas is introduced during the ball milling process.

[0014] In one preferred embodiment of the present invention, the raw material powder for cladding is dried before cladding, and the substrate is pretreated and preheated before cladding.

[0015] The present invention also discloses a high-entropy alloy coating, which is prepared by the above-described method for preparing a high-entropy alloy coating.

[0016] In one preferred embodiment of the present invention, the high-entropy alloy coating is AlCoCrFeMoNiTiCu x High-entropy alloy coating, where x ranges from 0.25 to 1.0.

[0017] In one preferred embodiment of the present invention, the thickness of the high-entropy alloy coating is 100μm-600μm.

[0018] In summary, the beneficial effects of the present invention are as follows:

[0019] 1. The method for preparing the high-entropy alloy coating of this invention uses traditional carbon steel as the substrate, and prepares the cladding raw material powder by a simple mechanical ball milling method. Then, it efficiently prepares AlCoCrFeMoNiTiCu coatings with adjustable thickness using a coaxial powder feeding high-speed laser cladding device. x The single-phase high-entropy alloy coating has high hardness and exhibits excellent corrosion resistance and gas-liquid erosion resistance. It can be used as a surface protective coating for downhole tubing and surface pipeline steel in the oil and gas industry.

[0020] 2. The AlCoCrFeMoNiTiCu prepared by this invention x In single-phase high-entropy alloy coatings, the x-value ranges from 0.25 to 1.0. The Cu content is controlled to produce a single-phase BCC microstructure, achieving high hardness and improving erosion resistance. (AlCoCrFeMoNiTiCu) x In high-entropy alloy coatings, x ≤ 1.0 ensures the coating possesses certain ductility and toughness, thus avoiding severe cracking during high-speed cladding. This invention, through high-entropy alloy composition design, achieves AlCoCrFeMoNiTiCu... x The reduced coefficient of thermal expansion between the coating and carbon steel significantly reduces the stress at the coating interface during high-speed cladding, thus decreasing the tendency to crack.

[0021] 3. The preparation method of the high-entropy alloy coating of the present invention utilizes high-speed laser cladding technology to prepare a high-entropy alloy coating of AlCoCrCuFeMoNiTi system with high corrosion resistance and wear resistance. By micro-adjusting the composition and preparation process parameters, the coating achieves a synergistic effect of high corrosion resistance and strong wear resistance, so that the coating can meet the harsh working conditions of oil and gas pipelines with high temperature, high acidity, high sulfur content, high carbon dioxide content and high chloride ion content.

[0022] 4. This invention improves wear resistance by controlling the microstructure of high-entropy alloys through microalloying. The addition of Al, Ti, and Cu metal elements induces the formation of hard phases and increases their volume fraction, thereby improving hardness. At the same time, Al and Ti elements are beneficial to the hardness and corrosion resistance of the alloy. By controlling the Cu element content, the ratio of BCC and FCC phases in the high-entropy alloy can be adjusted, thereby improving hardness and overall performance.

[0023] 5. The high-entropy alloy coating prepared by this invention has high hardness and high bonding strength, exhibiting excellent wear resistance and gas-liquid erosion resistance. The hardness is 650HV-800HV, and the wear resistance and gas-liquid erosion resistance are more than 20 times higher than those of traditional carbon steel. It is of great significance for improving the service life of oil and gas pipelines under harsh oil and gas conditions such as high temperature, high acid, high sulfur content, high carbon dioxide content, and high chloride ion content.

[0024] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention will be apparent from the effects described in the description and the accompanying drawings. Attached Figure Description

[0025] Figure 1 This is a macroscopic morphology diagram of the surface of the high-entropy alloy coating in Example 3 of the present invention;

[0026] Figure 2 This is a microscopic image of the surface morphology after the high-entropy alloy coating was prepared in Example 3 of the present invention;

[0027] Figure 3 This is a cross-sectional microstructure diagram of the high-entropy alloy coating in Example 3 of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0030] This invention provides a method for preparing a high-entropy alloy coating, such as... Figure 1 As shown, it includes the following steps:

[0031] Step (1): Mix the elemental powders of Al, Co, Cr, Fe, Mo, Ni, Ti and Cu to obtain cladding raw material powder; specifically, mix the elemental powders of Al, Co, Cr, Fe, Mo, Ni, Ti and Cu and ball mill them to obtain cladding raw material powder;

[0032] Among them, Al, Co, Cr, Fe, Mo, Ni, Ti and Cu elemental powders are spherical raw material powders with a particle size range of 53μm-105μm. During the ball milling process, the ball-to-material ratio is 3-10:1, the ball milling speed is 100r / min-300r / min, and the ball milling time is 3h-12h. This is to ensure good sphericity while ensuring uniform powder mixing, thereby controlling the uniform distribution of composition, structure and thickness of the cladding coating.

[0033] Furthermore, argon gas is introduced during the ball milling process to maintain good sphericity while ensuring uniform powder mixing;

[0034] Furthermore, the raw material powder for cladding is dried before cladding. The drying process involves baking the mixed powder in a vacuum drying oven at 80℃-150℃ for more than 50 minutes to remove moisture, ensure good powder flowability, and reduce the formation of pore defects inside the coating during the cladding process.

[0035] Step (2): The cladding raw material powder is clad onto the surface of the substrate to prepare a high-entropy alloy coating. The cladding process parameters are: laser cladding power of 1kW-2.5kW, laser scanning rate of 3000mm / min-10000mm / min, and cladding overlap rate of 60%-90%. By designing a higher laser scanning rate, the coating cladding preparation efficiency can be improved, and fine microstructure can be obtained. On the other hand, by optimizing the laser power and cladding rate, the internal defects of pores and cracks in the single-phase BCC coating during high-speed cladding can be avoided. By designing the overlap rate, the coating thickness and surface roughness can be controlled in a wide range, while the dilution rate during the coating cladding process can be kept low.

[0036] The substrate is traditional carbon steel. Before deposition on the substrate surface, the surface of the substrate material is first subjected to rust removal, grinding, polishing, cleaning and baking pretreatment to ensure good bonding performance between the cladding coating and the substrate.

[0037] Furthermore, the substrate needs to be preheated before laser cladding, with a preheating temperature of 200℃-500℃, in order to reduce the cracking of the high-hardness coating during high-speed cladding.

[0038] This invention also discloses a high-entropy alloy coating, prepared using the aforementioned method, wherein the high-entropy alloy coating is AlCoCrFeMoNiTiCu. x A single-phase high-entropy alloy coating, wherein x ranges from 0.25 to 1.0, and the thickness of the high-entropy alloy coating is 100 μm to 600 μm.

[0039] The high-entropy alloy coating prepared by this invention has high hardness and high bonding strength, exhibiting excellent wear resistance and gas-liquid erosion resistance. The hardness is 650HV-800HV, and the wear resistance and gas-liquid erosion resistance are more than 20 times higher than those of traditional carbon steel.

[0040] Example 1

[0041] A method for preparing a high-entropy alloy coating includes the following steps:

[0042] (1) Using L360N steel pipe as the base, the surface of the pipe is ground, sandblasted and cleaned with anhydrous ethanol to obtain a clean metal surface, and then dried.

[0043] (2) Al, Co, Cr, Fe, Mo, Ni, Ti, and Cu elemental powders with an average particle size of 53 μm were weighed at a molar ratio of 1:1:1:1:1:1:1:0.25. The powders were then placed in a polytetrafluoroethylene-lined vacuum ball mill jar. The ball-to-powder ratio was set to 3:1, the milling speed was 300 r / min, and the milling time was 12 h. Argon gas was used for protection during the milling process to obtain AlCoCrFeMoNiTiCu. 0.25 High-entropy alloy cladding powder;

[0044] (3) Before laser cladding, the spherical mixed high-entropy alloy cladding powder is baked in a vacuum drying oven at 100°C for 100 min; at the same time, the substrate needs to be preheated at 200°C.

[0045] (4) The laser power was set to 2.5kW, the laser scanning rate to 10000mm / min, and the cladding overlap rate to 90%. Argon was used as the powder feed gas (5L / min) and the protective gas (12L / min) to prepare AlCoCrFeMoNiTiCu on the surface of the substrate tube. 0.25 High-entropy alloy coating;

[0046] (5) The high-entropy alloy coating has good metallurgical bonding with the substrate and no defects inside the high-entropy alloy coating; the high-entropy alloy coating has a single-phase BCC structure and an average hardness of 650HV. The corrosion and erosion resistance of the high-entropy alloy coating is 5 times higher than that of L360N.

[0047] Example 2

[0048] A method for preparing a high-entropy alloy coating includes the following steps:

[0049] (1) Using L360N steel pipe as the base, the surface of the pipe is ground, sandblasted and cleaned with anhydrous ethanol to obtain a clean metal surface, and then dried.

[0050] (2) Al, Co, Cr, Fe, Mo, Ni, Ti, and Cu elemental powders with an average particle size of 53 μm were weighed at a molar ratio of 1:1:1:1:1:1:1:0.5. The powders were then placed in a polytetrafluoroethylene-lined vacuum ball mill jar. The ball-to-powder ratio was set to 3:1, the milling speed was 300 r / min, and the milling time was 6 h. Argon gas was used for protection during the milling process to obtain AlCoCrFeMoNiTiCu. 0.5 High-entropy alloy cladding powder;

[0051] (3) Before laser cladding, the spherical mixed high-entropy alloy cladding powder is baked in a vacuum drying oven at 100°C for 100 min; at the same time, the substrate needs to be preheated at 200°C.

[0052] (4) The laser power was set to 2.5kW, the laser scanning rate to 10000mm / min, and the cladding overlap rate to 90%. Argon was used as the powder feed gas (5L / min) and the protective gas (12L / min) to prepare AlCoCrFeMoNiTiCu on the surface of the substrate tube. 0.5 High-entropy alloy coating;

[0053] (5) The high-entropy alloy coating obtained exhibits good metallurgical bonding with the substrate, and there are no defects inside the high-entropy alloy coating; the coating has a single-phase BCC structure, and the average hardness of the high-entropy alloy coating is 700HV. The corrosion resistance and erosion resistance of the high-entropy alloy coating are 10 times higher than those of L360N.

[0054] Example 3

[0055] (1) Using L360N steel pipe as the base, the surface of the pipe is ground, sandblasted and cleaned with anhydrous ethanol to obtain a clean metal surface, and then dried.

[0056] (2) Al, Co, Cr, Fe, Mo, Ni, Ti and Cu elemental powders with an average particle size of 53 μm were weighed in a molar ratio of 1:1:1:1:1:1:1:1. The powders were then placed in a vacuum ball mill jar lined with polytetrafluoroethylene. The ball-to-material ratio was set to 3:1, the ball milling speed was 300 r / min, and the ball milling time was 3 h. Argon gas was used for protection during the ball milling process to obtain AlCoCrFeMoNiTiCu high-entropy alloy cladding powder.

[0057] (3) Before laser cladding, the spherical mixed high-entropy alloy cladding powder is baked in a vacuum drying oven at 100°C for 100 min; at the same time, the substrate needs to be preheated at 200°C.

[0058] (4) Set the laser power to 2.5kW, the laser scanning rate to 10000mm / min, the cladding overlap rate to 90%, and use argon as the powder feeding gas (5L / min) and protective gas (12L / min) to prepare an AlCoCrFeMoNiTiCu high-entropy alloy coating on the surface of the substrate tube.

[0059] (5) The high-entropy alloy coating has a good metallurgical bond with the substrate and no defects inside the high-entropy alloy coating; the high-entropy alloy coating has a single-phase BCC structure and an average hardness of 800HV. The corrosion resistance and erosion resistance of the high-entropy alloy coating are 20 times higher than those of L360N.

[0060] Comparative Example 1

[0061] (1) Using TP347 steel pipe as the base, the surface of the pipe is ground, sandblasted and cleaned with anhydrous ethanol to obtain a clean metal surface, and then dried.

[0062] (2) Al, Co, Cr, Fe, and Ni elemental powders with an average particle size of 53 μm were weighed at a molar ratio of 1.3:1:1:1.5:2.1. The powders were then placed in a polytetrafluoroethylene-lined vacuum ball mill jar. The ball-to-powder ratio was set to 3:1, the milling speed to 300 r / min, and the milling time to 12 h. Argon gas was used for protection during the milling process to obtain Al… 1.3 CoCrFe 1.5 Ni 2.1 High-entropy alloy cladding powder;

[0063] (3) Before laser cladding, the spherical mixed powder is baked in a vacuum drying oven at 100°C for 100 min; at the same time, the substrate needs to be preheated at 200°C.

[0064] (4) The laser power was set to 2.5kW, the laser scanning rate to 10000mm / min, and the cladding overlap rate to 90%. Argon was used as the powder feed gas (5L / min) and the protective gas (12L / min) to prepare Al on the surface of the substrate tube. 1.3 CoCrFe 1.5 Ni 2.1 Single-phase high-entropy alloy coating;

[0065] (5) The coating and the substrate exhibit good metallurgical bonding and there are no defects inside the coating; the coating is a single-phase BCC structure and the average hardness of the coating is 602HV. The coating's resistance to high-temperature solid particle erosion is 5 times higher than that of the substrate.

[0066] Comparative Example 2

[0067] (1) Using TP347 steel pipe as the base, the surface of the pipe is ground, sandblasted and cleaned with anhydrous ethanol to obtain a clean metal surface, and then dried.

[0068] (2) Al, Co, Cr, Fe, and Ni elemental powders with an average particle size of 65 μm were weighed at a molar ratio of 1.5:1:1:1.5:2.1. The powders were then placed in a polytetrafluoroethylene-lined vacuum ball mill jar. The ball-to-powder ratio was set to 10:1, the milling speed to 100 r / min, and the milling time to 6 h. Argon gas was used for protection during the milling process to obtain Al... 1.5 CoCrFe 1.5 Ni 2.1 High-entropy alloy cladding powder;

[0069] (3) Before laser cladding, the spherical mixed powder is baked in a vacuum drying oven at 120°C for 80 minutes; at the same time, the substrate needs to be preheated at 300°C.

[0070] (4) The laser power was set to 1.5kW, the laser scanning rate to 6000mm / min, and the cladding overlap rate to 80%. Argon was used as the powder feeding gas (5L / min) and the protective gas (12L / min) to prepare Al on the surface of the substrate tube. 1.5 CoCrFe 1.5 Ni 2.1 Single-phase high-entropy alloy coating;

[0071] (5) The coating and the substrate exhibit good metallurgical bonding and there are no defects inside the coating; the coating is a single-phase BCC structure and the average hardness of the coating is 600HV. The coating's resistance to high-temperature solid particle erosion is 7.4 times higher than that of the substrate.

[0072] By comparing the average hardness of the high-entropy alloy coatings prepared in Examples 1-3 and Comparative Examples 1-2, it can be seen that the average hardness of the high-entropy alloy coatings prepared in Examples 1-3 is significantly higher than that of the high-entropy alloy coatings prepared in the comparative examples.

[0073] In summary, the high-entropy alloy coating prepared by this invention has high hardness and high bonding strength, exhibiting excellent wear resistance and resistance to gas-liquid erosion.

[0074] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a high-entropy alloy coating, characterized in that, Includes the following steps: The powders of elemental elements Al, Co, Cr, Fe, Mo, Ni, Ti and Cu are mixed to obtain the cladding raw material powder; wherein the molar ratio of elemental elemental powders of Al, Co, Cr, Fe, Mo, Ni, Ti and Cu is 1:1:1:1:1:1:1:0.25-1; High-entropy alloy coatings are prepared by cladding raw material powder onto the surface of a substrate.

2. The method for preparing a high-entropy alloy coating as described in claim 1, characterized in that, The cladding process parameters are as follows: laser cladding power is 1kW-2.5kW, laser scanning rate is 3000mm / min-10000mm / min, and cladding overlap rate is 60%-90%.

3. The method for preparing a high-entropy alloy coating as described in claim 1, characterized in that, The process of mixing Al, Co, Cr, Fe, Mo, Ni, Ti and Cu elemental powders to obtain cladding raw material powder includes: mixing Al, Co, Cr, Fe, Mo, Ni, Ti and Cu elemental powders and ball milling them to obtain cladding raw material powder.

4. The method for preparing a high-entropy alloy coating as described in claim 3, characterized in that: The particle size of the elemental powder is 53μm-105μm.

5. The method for preparing a high-entropy alloy coating as described in claim 3, characterized in that: The ball-to-material ratio of the ball mill is 3-10:1, the ball milling speed is 100r / min-300r / min, and the ball milling time is 3h-12h.

6. The method for preparing a high-entropy alloy coating as described in claim 3, characterized in that: Argon gas is introduced during the ball milling process.

7. The method for preparing a high-entropy alloy coating as described in claim 1, characterized in that: The cladding raw material powder is dried before cladding, and the substrate is pretreated and preheated before cladding.

8. A high-entropy alloy coating, characterized in that: It is prepared by the method for preparing a high-entropy alloy coating according to any one of claims 1-7.

9. The high-entropy alloy coating as described in claim 8, characterized in that: The high-entropy alloy coating is AlCoCrFeMoNiTiCu x High-entropy alloy coating, where x ranges from 0.25 to 1.

0.

10. The high-entropy alloy coating as described in claim 8, characterized in that: The thickness of the high-entropy alloy coating is 100μm-600μm.

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