High-entropy alloy coating resistant to high-temperature sulfur corrosion

Abstract

The invention discloses a high-entropy alloy coating resistant to high-temperature sulfur corrosion. The high-entropy alloy coating is formed by mixing chromium, molybdenum, nickel, titanium, aluminum, copper and silicon. The high-entropy alloy coating comprises the following components in percentage by weight: 25% of chromium (Cr); molybdenum (Mo): 15%; 20% of nickel (Ni); titanium (Ti): 15%; aluminum (Al): 10%; 7.5% of copper (Cu); and silicon (Si): 7.5%. Through the optimized proportion design and the spherical particle process, the comprehensive effects of high temperature resistance, sulfur corrosion resistance, enhanced adhesive force and improved hardness and wear resistance are successfully achieved; by adopting spherical particle configuration, the uniformity, the stability, the adhesive force, the thermal stability, the sulfur corrosion resistance, the hardness and the wear resistance of the coating can be improved; and by combining an advanced thermal spraying, laser cladding or plasma cladding process, the coating has a wide application prospect in high-temperature, corrosive and frictional industrial environments, the service life of equipment can be remarkably prolonged, the maintenance cost can be reduced, and the coating has extremely high economic benefits and technical popularization values.

Description

Technical Field

[0001] The invention relates to the technical field of high entropy alloy coatings, and in particular to a high entropy alloy coating resistant to high temperature sulfur corrosion. Background Art

[0002] As a new type of functional coating material, high entropy alloy coating has been widely used in high temperature, corrosive and friction environments in recent years, especially in the protection of key components such as gas turbines, heat exchangers, and petrochemical equipment. Due to its complex element combination and high entropy value, high entropy alloy coating has good comprehensive properties, such as oxidation resistance, wear resistance and high temperature strength. However, although high entropy alloy coating has made significant progress in some fields, its application in specific environments, especially in high temperature sulfur corrosion environments, still faces many challenges.

[0003] Although high-entropy alloy coatings have certain advantages in high-temperature resistance, their corrosion resistance and durability still cannot meet the requirements in extreme environments (such as high-temperature sulfur-containing atmospheres). In high-temperature sulfur corrosion environments, traditional high-entropy alloy coatings are susceptible to sulfide corrosion, causing cracks and shedding on the coating surface, thereby shortening its service life. Although some studies have attempted to improve the corrosion resistance of coatings by adjusting the element ratio, existing technologies have not been able to effectively solve this problem, especially when exposed to high-temperature sulfur corrosion environments for a long time. Existing coatings are easily affected by corrosion and cannot provide continuous and stable protection.

[0004] The existing high entropy alloy coatings also have certain deficiencies in terms of adhesion and hardness. In practical applications, the bonding strength between the coating and the substrate is often insufficient, especially in high temperature, impact and corrosion environments, the coating is prone to peeling, resulting in coating failure and affecting its long-term protective effect. In order to enhance the adhesion of the coating, some studies have tried to add copper elements. However, the effectiveness of this method in practical applications remains to be verified, especially how to optimize the element ratio to obtain the best adhesion and corrosion resistance, which is still a technical problem that needs to be solved urgently.

[0005] In terms of hardness and wear resistance, although existing high entropy alloy coatings can provide certain wear protection, they still cannot meet the long-term application requirements in high wear environments. Traditional high entropy alloy coatings are often brittle and prone to microcracks, resulting in insufficient wear resistance of the coating. Although the addition of elements such as titanium and silicon can increase the hardness of the coating, how to ensure the wear resistance of the coating while avoiding coating embrittlement is still a key issue in coating design.

[0006] Existing coating processes, such as thermal spraying, laser cladding and plasma spraying, can improve the uniformity and density of coatings to a certain extent, but these traditional processes still have some shortcomings. For example, the spraying process often leads to a rough coating surface, affecting the smoothness and uniformity of the coating, while laser cladding and plasma spraying require higher process control, and the coating thickness is difficult to control uniformly, resulting in the stability and reliability of the coating being difficult to ensure. Therefore, the existing technology still has many shortcomings in terms of coating uniformity, stability and adhesion, and cannot meet the long-term application requirements in high-temperature sulfur corrosion environments.

[0007] Although some studies have attempted to improve the above problems by optimizing the coating process and element ratio, the existing technology still faces a bottleneck in improving the coating performance, especially in terms of resistance to high-temperature sulfur corrosion, adhesion, hardness and wear resistance. The effect of the existing coating still cannot reach the ideal level. The existence of these technical difficulties limits the widespread application of high-entropy alloy coatings in certain high-temperature corrosive environments, and a new technical solution is urgently needed to overcome these defects.

[0008] Therefore, how to provide a high entropy alloy coating that is resistant to high temperature sulfur corrosion is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0009] One purpose of the present invention is to propose a high-entropy alloy coating that is resistant to high-temperature sulfur corrosion. The present invention successfully achieves the comprehensive effects of high-temperature resistance, sulfur corrosion resistance, enhanced adhesion, and improved hardness and wear resistance through optimized ratio design and spherical particle technology; the spherical particle configuration is adopted to improve the uniformity, stability, adhesion, thermal stability, sulfur corrosion resistance, hardness and wear resistance of the coating; combined with advanced thermal spraying, laser cladding or plasma cladding technology, the coating has broad application prospects in high-temperature, corrosive and frictional industrial environments, can significantly extend the life of equipment, reduce maintenance costs, and has extremely high economic benefits and technology promotion value.

[0010] A high-entropy alloy coating resistant to high-temperature sulfur corrosion according to an embodiment of the present invention comprises a mixture of chromium, molybdenum, nickel, titanium, aluminum, copper and silicon;

[0011] Ratio of high entropy alloy coating:

[0012] Chromium (Cr): 25%;

[0013] Molybdenum (Mo): 15%;

[0014] Nickel (Ni): 20%;

[0015] Titanium (Ti): 15%;

[0016] Aluminum (Al): 10%;

[0017] Copper (Cu): 7.5%;

[0018] Silicon (Si): 7.5%.

[0019] Furthermore, the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon are arranged in a spherical shape.

[0020] Furthermore, the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon are atomized by high-pressure gas and formed into spherical powder after cooling.

[0021] Furthermore, the spheroidization rates of the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon are higher than 95%.

[0022] Furthermore, the particle size of the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon particles is 20-105 μm.

[0023] Furthermore, the particle size of the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon particles is 20-48 μm and thermal spraying is used.

[0024] Furthermore, the temperature range of the thermal spraying is 2000-3000°C.

[0025] Furthermore, the particle size of chromium, molybdenum, nickel, titanium, aluminum, copper and silicon is 45-105 μm and is clad by laser or plasma.

[0026] Furthermore, the temperature range of the laser cladding is 1500-2000°C.

[0027] Furthermore, the temperature range of the plasma cladding is 3000-3500°C.

[0028] The beneficial effects of the present invention are:

[0029] The present invention has demonstrated excellent performance improvement through optimized element ratio and reasonable process design. The following is a summary of its specific beneficial effects:

[0030] 1. Significant high temperature resistance: High entropy alloy coating has excellent anti-oxidation and thermal stability in high temperature environment, can effectively prevent high temperature oxidation and thermal fatigue damage, and is particularly suitable for high temperature industrial environment.

[0031] 2. Excellent resistance to sulfur corrosion; through reasonable element design (such as the addition of chromium, molybdenum and aluminum), the coating exhibits extremely strong corrosion resistance in high-temperature sulfur-containing atmospheres, which can significantly extend the service life of key components in corrosive environments.

[0032] 3. Enhanced adhesion: The addition of copper to the element ratio significantly improves the bonding strength between the coating and the substrate, making the coating less likely to peel off under high temperature, impact or corrosion conditions, ensuring the reliability of the coating.

[0033] 4. Superior hardness and wear resistance; the titanium, silicon and other elements in the high entropy alloy coating and the dense microstructure greatly improve the hardness and wear resistance of the coating, and can effectively reduce the loss of parts caused by friction.

[0034] 5. Wide application value: The coating is particularly suitable for the protection of key components in high temperature, corrosive and frictional environments in industry, such as gas turbines, heat exchangers, petrochemical equipment and high-temperature pipelines, and has significant technical advantages and practical application value.

[0035] The present invention further optimizes the coating performance by using spherical particles in the coating, and its specific advantages are as follows:

[0036] 1. Improve the uniformity and structural stability of the coating; the high fluidity and uniformity of the spherical particles make the coating present a dense and uniform structure after coating, effectively avoiding the generation of cracks and pores, thereby significantly improving the stability and failure resistance of the coating.

[0037] 2. Enhance the adhesion of the coating; the spherical particles can be more evenly distributed on the substrate surface during the cladding process, forming a strong metallurgical bond with the substrate, effectively reducing the risk of coating peeling.

[0038] 3. Improve the thermal stability and high temperature resistance of the coating; spherical particles can better form a dense oxide film in a high temperature environment, further improving the durability of the coating in a high temperature environment.

[0039] 4. Enhance the coating's anti-sulfur corrosion performance; spherical particles help the coating form a continuous protective film in a corrosive environment, avoid sulfide corrosion, and extend the coating life.

[0040] 5. Improve the hardness and wear resistance of the coating; since the coating surface formed by spherical particles is smooth and dense, it reduces the occurrence of wear and surface cracks, making the coating more adaptable to high wear environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0042] Figure 1 This is a flow chart for preparing a high-entropy alloy coating resistant to high-temperature sulfur corrosion proposed by the present invention. DETAILED DESCRIPTION

[0043] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0044] The existing high-entropy alloy coatings also have certain deficiencies in terms of adhesion and hardness. In practical applications, the bonding strength between the coating and the substrate is often insufficient, especially in high temperature, impact and corrosion environments. The coating is prone to peeling, resulting in coating failure and affecting its long-term protective effect. In order to enhance the adhesion of the coating, some studies have attempted to add copper elements. However, the effectiveness of this method in practical applications remains to be verified, especially how to optimize the element ratio to obtain the best adhesion and corrosion resistance, which is still a technical problem that needs to be solved urgently.

[0045] In terms of hardness and wear resistance, although existing high entropy alloy coatings can provide certain wear protection, they still cannot meet the long-term application requirements in high wear environments. Traditional high entropy alloy coatings are often brittle and prone to microcracks, resulting in insufficient wear resistance of the coatings. Although the addition of elements such as titanium and silicon can increase the hardness of the coatings, how to ensure the wear resistance of the coatings while avoiding embrittlement of the coatings is still a key issue in coating design.

[0046] Although existing coating processes, such as thermal spraying, laser cladding and plasma spraying, can improve the uniformity and density of the coating to a certain extent, these traditional processes still have some shortcomings; for example, the spraying process often leads to a rough coating surface, affecting the smoothness and uniformity of the coating, while laser cladding and plasma spraying require higher process control, and the coating thickness is difficult to control uniformly, resulting in difficulty in ensuring the stability and reliability of the coating.

[0047] In order to solve the above problems, the following technical solutions are proposed:

[0048] Please refer to Figure 1 , the present invention provides a high entropy alloy coating resistant to high temperature sulfur corrosion, comprising a mixture of chromium, molybdenum, nickel, titanium, aluminum, copper and silicon;

[0049] Ratio of high entropy alloy coating:

[0050] Chromium (Cr): 25%;

[0051] Molybdenum (Mo): 15%;

[0052] Nickel (Ni): 20%;

[0053] Titanium (Ti): 15%;

[0054] Aluminum (Al): 10%;

[0055] Copper (Cu): 7.5%;

[0056] Silicon (Si): 7.5%.

[0057] Specifically, the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon are arranged in a spherical shape; the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon are atomized by high-pressure gas and form spherical powders after cooling; the spheroidization rate of the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon is higher than 95%; the particle size of the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon is 20-105μm.

[0058] More specifically, the particle size of chromium, molybdenum, nickel, titanium, aluminum, copper and silicon is 20-48μm and thermal spraying is used; the temperature range of the thermal spraying is 2000-3000℃; the particle size of chromium, molybdenum, nickel, titanium, aluminum, copper and silicon is 45-105μm and laser cladding or plasma cladding is used; the temperature range of the laser cladding is 1500-2000℃; the temperature range of the plasma cladding is 3000-3500℃.

[0059] The role of each element in high entropy alloy coating:

[0060] Chromium is an important antioxidant and anti-corrosion element, especially with excellent oxidation resistance in high temperature environments; it can form a stable oxide film on the coating surface, thereby reducing oxidation reactions; in addition, chromium also enhances the sulfur corrosion resistance of high-entropy alloys and improves the wear resistance and hardness of the coating.

[0061] Molybdenum has good stability at high temperatures and can improve the oxidation resistance and corrosion resistance of the alloy, especially enhance the mechanical properties of the alloy at high temperatures; molybdenum can also stabilize the microstructure of the alloy and prevent the grain growth of the alloy during overheating, thereby improving the high temperature resistance and sulfur corrosion resistance of the coating.

[0062] Nickel can improve the toughness and plasticity of the alloy and enhance its oxidation resistance at high temperatures; it can also form stable compounds with other metal elements, which helps to improve the corrosion resistance of the alloy, especially against corrosion in acid and alkaline environments; in addition, nickel helps to form a uniform coating structure during the melting and solidification process of the coating.

[0063] Titanium has very good oxidation resistance and corrosion resistance in high temperature environments, especially in sulfur-containing atmospheres; titanium can react with elements such as oxygen and nitrogen to form a dense titanium oxide film, which effectively protects the base material from corrosion; titanium can also improve the hardness and wear resistance of the coating and enhance the coating's resistance to high temperature sulfur corrosion.

[0064] Aluminum has extremely strong oxidation resistance and can quickly form a dense aluminum oxide film at high temperatures, effectively preventing the occurrence of oxidation reactions; aluminum also has excellent high temperature resistance and sulfur corrosion resistance, and can effectively slow down the corrosion of the coating in a sulfurized environment; in addition, aluminum can improve the thermal stability of the alloy and enhance the high temperature resistance of the coating.

[0065] Copper can improve the adhesion between the coating and the substrate, enhance the bonding strength of the alloy coating, and reduce the risk of coating peeling; copper also has good oxidation resistance in high temperature environments and can improve the high temperature resistance of the alloy; at the same time, the addition of copper helps the coating to form a better microstructure during the cooling process and improves the uniformity of the coating.

[0066] Silicon has strong antioxidant properties and can promote the formation of oxide film at high temperatures, enhancing the high temperature resistance of the alloy; silicon can also improve the hardness and wear resistance of the coating, and enhance the corrosion resistance of the coating under extreme conditions; silicon can also improve the surface finish of the coating, reduce pores and defects, thereby improving the quality of the coating.

[0067] Example 1: Proportion and preparation process of high entropy alloy coating

[0068] Ratio of high entropy alloy coating:

[0069] Chromium (Cr): 25%;

[0070] Molybdenum (Mo): 15%;

[0071] Nickel (Ni): 20%;

[0072] Titanium (Ti): 15%;

[0073] Aluminum (Al): 10%;

[0074] Copper (Cu): 7.5%;

[0075] Silicon (Si): 7.5%.

[0076] Preparation of spherical powder by high pressure gas atomization:

[0077] In this embodiment, chromium, molybdenum, nickel, titanium, aluminum, copper and silicon elements are powdered by high-pressure gas atomization. In this process, high-pressure gas is used to spray these alloy elements into a low-temperature environment, and spherical powder is formed by rapid cooling. The spheroidization rate of the formed powder exceeds 95%, and the particle size range of the spherical powder particles is 20-105μm. Specifically, powders with a particle size of 20-48μm are suitable for thermal spraying, and powders with a particle size of 45-105μm are suitable for laser cladding or plasma cladding.

[0078] Thermal spraying process:

[0079] Powders with a particle size of 20-48μm are coated using a thermal spraying process; the thermal spraying temperature is controlled between 2000-3000℃ to ensure that the powder quickly melts at high temperature and is sprayed onto the substrate surface to form a coating; during the coating formation process, the powder quickly cools and solidifies to form a dense coating structure; the advantages of the thermal spraying process are uniform coating, strong adhesion, and can effectively prevent oxidation and corrosion of the substrate material.

[0080] Laser cladding process:

[0081] Powders with a particle size of 45-105μm are coated using a laser cladding process. The laser power is controlled between 1-5kW, and the temperature range of laser cladding is 1500-2000℃; the laser beam can accurately heat the powder and melt it to combine with the substrate; laser cladding can provide higher coating density and better bonding strength, and is suitable for high temperature and high pressure environments.

[0082] Plasma cladding process:

[0083] Powders with the same particle size of 45-105μm can also be coated by plasma cladding process, with the plasma arc temperature controlled between 3000-3500℃; plasma cladding can provide higher heat input and is suitable for environments that require strong high temperature resistance and sulfur corrosion resistance; this process can ensure that the powder forms a uniform and dense coating on the substrate surface.

[0084] Example 2: Performance test of coating

[0085] Ratio of high entropy alloy coating:

[0086] Chromium (Cr): 25%;

[0087] Molybdenum (Mo): 15%;

[0088] Nickel (Ni): 20%;

[0089] Titanium (Ti): 15%;

[0090] Aluminum (Al): 10%;

[0091] Copper (Cu): 7.5%;

[0092] Silicon (Si): 7.5%.

[0093] Test method:

[0094] High temperature resistance:

[0095] In this embodiment, an oxidation test was performed by exposing the coating sample to a high temperature environment of 1000°C; the test results showed that the oxide film formed on the surface of the coating was dense and stable, which effectively prevented oxidation of the coating and corrosion of the substrate.

[0096] Anti-sulfur corrosion performance:

[0097] Corrosion tests were carried out in a sulfur-containing atmosphere, and the sulfur corrosion loss of the coating was low; through SEM and EDS analysis of the coating surface, it was found that the elements such as chromium, molybdenum and aluminum in the coating formed a stable protective oxide layer, which inhibited the corrosion of sulfides.

[0098] Adhesion test:

[0099] The peeling test method was used to evaluate the adhesion between the coating and the substrate; the results showed that under the thermal spraying process, the adhesion between the coating and the substrate reached a good level and the coating did not peel off.

[0100] Implementation results:

[0101] The high-entropy alloy coating can still maintain good structural stability in high-temperature environments and exhibit excellent corrosion resistance in sulfur corrosion environments; the coating has good adhesion and does not fall off or peel off, making it suitable for industrial applications that require high-temperature corrosion resistance.

[0102] Example 3: Ratio optimization and performance improvement

[0103] Testing and Improvement: Based on Examples 1 and 2, the element ratio of the high entropy alloy coating was optimized to further improve its high temperature resistance, sulfur corrosion resistance and adhesion performance; by adjusting the element ratio, the optimal combination of chromium, molybdenum, nickel, titanium, aluminum, copper and silicon was studied to maximize the wear resistance and corrosion resistance of the coating.

[0104] Test results:

[0105] After adding silicon, the anti-oxidation ability of the coating is further improved, the oxide film is denser, and the occurrence of oxidation corrosion is reduced.

[0106] After adding copper elements, the adhesion between the coating and the substrate is enhanced, avoiding coating peeling in high temperature or corrosive environments.

[0107] 1. Introduction to high entropy alloy coating process

[0108] The preparation of high entropy alloy coatings is completed through specific coating processes (such as thermal spraying, laser cladding or plasma cladding), which can coat high entropy alloy powders onto the surface of the substrate to form a dense, wear-resistant, high-temperature resistant and sulfur-corrosion-resistant coating.

[0109] 1. Thermal spraying process

[0110] Thermal spraying is a method of using a high-temperature heat source (such as a combustion flame or plasma arc) to heat high-entropy alloy powder to a molten or semi-molten state, and then spraying the powder onto the surface of the substrate through a high-speed airflow to form a coating.

[0111] 1.1. Process characteristics:

[0112] Spherical powders with a particle size of 20-48 μm were used.

[0113] The thermal spraying temperature is controlled at 2000-3000℃ to ensure that the powder is completely melted.

[0114] During the spraying process, the molten powder hits the substrate surface at high speed and cools rapidly to form a dense coating.

[0115] 1.2 Advantages:

[0116] High efficiency: fast spraying speed, suitable for large area coating.

[0117] Flexible process: Uniform coatings can be formed on substrates with complex geometries.

[0118] Lower cost: Compared with other cladding processes, the equipment and material costs are lower.

[0119] 1.3 Limitations:

[0120] The coating density may be slightly inferior to laser cladding and plasma cladding.

[0121] The bonding strength between the coating and the substrate is limited and is suitable for moderate temperature and stress environments.

[0122] 2. Laser cladding process

[0123] Laser cladding uses a high-energy laser beam as a heat source to melt the high-entropy alloy powder and partially melt it with the substrate before cooling to form a dense coating; laser cladding is usually used for high-entropy alloy coatings that require high bonding strength and density.

[0124] 2.1. Process characteristics:

[0125] Spherical powders with a particle size of 45-105 μm were used.

[0126] The cladding temperature range is 1500-2000℃, and the temperature control during the cladding process is precise.

[0127] The laser power can be adjusted according to the matrix material and powder characteristics (usually 1-5kW).

[0128] 2.2 Advantages:

[0129] High coating density: The formed coating has a uniform structure and low porosity.

[0130] High bonding strength: The coating and substrate achieve higher adhesion through metallurgical bonding.

[0131] Small heat-affected zone: The laser beam heats precisely to reduce thermal deformation of the substrate.

[0132] 2.3 Limitations:

[0133] The process is complex and requires high operating precision.

[0134] The equipment cost is relatively high and is suitable for high value-added coating applications.

[0135] 3. Plasma cladding process

[0136] Plasma cladding uses the high temperature (up to 3000-3500°C) generated by a plasma arc to melt high entropy alloy powder and deposit it on the surface of the substrate to form a coating; this process is suitable for environments where the coating material has a high melting point or requires a higher temperature.

[0137] 3.1. Process characteristics:

[0138] Spherical powders with a particle size of 45-105 μm were used.

[0139] The temperature range of plasma arc is 3000-3500℃, which can fully melt high entropy alloy powder.

[0140] After melting, the powder is deposited on the substrate surface at high speed through the plasma jet.

[0141] 3.2 Advantages:

[0142] Wide range of applications: can clad high melting point materials, suitable for harsh environments.

[0143] High coating quality: density and bonding strength are comparable to laser cladding.

[0144] High efficiency: fast coating speed, suitable for thick coating preparation.

[0145] 3.3 Limitations:

[0146] High temperature environments have a greater thermal impact on the substrate and may require additional cooling measures.

[0147] The equipment is complex and the operating cost is high.

[0148] 4. Process comparison summary:

[0149] Process Name Thermal Spraying Laser Cladding Plasma Cladding Temperature range 2000-3000℃ 1500-2000℃ 3000-3500℃ Powder particle size range 20-48μm 45-105μm 45-105μm Coating density medium high high Coating bonding strength Mechanical bonding Metallurgical bonding Metallurgical bonding Heat affected zone medium Small medium Applicable scenarios Large area coating Precision coating, high bonding strength High temperature and wear resistant coating

[0150] 2. Advantages of high entropy alloy coatings resistant to high temperature sulfur corrosion:

[0151] 1. Excellent high temperature resistance

[0152] Elements such as chromium (Cr), molybdenum (Mo) and nickel (Ni) help the alloy form a stable oxide film in a high temperature environment and enhance its high temperature resistance.

[0153] Chromium (Cr): Chromium can form a chromium oxide film (Cr2O3) under high temperature conditions. This film has strong heat resistance and oxidation resistance, and can effectively protect the metal substrate from oxidation corrosion; especially at high temperatures, the Cr2O3 oxide film has self-healing properties and can repair itself when damaged to maintain protective properties.

[0154] Molybdenum (Mo): Molybdenum can enhance the heat resistance of the alloy at high temperatures and promote the formation of high-temperature stable phases; Molybdenum can improve the high-temperature strength and oxidation resistance of the material, prevent the peeling of the oxide film, and thus enhance the high-temperature resistance of the coating.

[0155] Nickel (Ni): Nickel can improve the thermal stability of the material and help form a stable oxide film to enhance oxidation resistance; Nickel also has good thermal conductivity, which helps the coating to disperse heat at high temperatures, prevent overheating in high-temperature areas, and maintain the structural integrity of the alloy.

[0156] Chromium, molybdenum and nickel can effectively prevent the alloy from undergoing oxidation reactions in high-temperature environments, forming a stable protective film, thereby improving the material's high-temperature resistance; under high-temperature conditions, these elements can maintain the stability of the alloy surface, preventing matrix oxidation and performance degradation.

[0157] 2. Excellent anti-sulfur corrosion performance

[0158] Elements such as molybdenum (Mo), titanium (Ti), and aluminum (Al) can effectively improve the alloy's resistance to sulfur corrosion, especially in high-temperature sulfur-containing environments.

[0159] Molybdenum (Mo): Molybdenum has strong resistance to sulfur corrosion and can form stable molybdenum oxide on the surface to prevent sulfide corrosion on the alloy; Molybdenum can effectively reduce the dissolution of sulfide and enhance the alloy's resistance to sulfur corrosion.

[0160] Titanium (Ti): Titanium can form a high temperature resistant and corrosion resistant oxide film (TiO2) on the alloy surface, forming a protective film in a high temperature sulfiding environment to prevent the intrusion of sulfides.

[0161] Aluminum (Al): The addition of aluminum can increase the material's resistance to sulfur corrosion by forming an aluminum oxide (Al2O3) film; the aluminum oxide film has strong corrosion resistance and can effectively isolate the contact between sulfides and the metal substrate, thereby extending the service life of the coating.

[0162] The molybdenum, titanium and aluminum contained in the alloy can form a dense protective film through oxidation reaction in a high-temperature sulfiding environment, effectively isolating the substrate from contact with external sulfides, thereby significantly improving the ability to resist sulfur corrosion; this protective mechanism enables the coating to maintain stability for a long time in harsh sulfiding environments.

[0163] 3. Improve the adhesion between coating and substrate

[0164] The role of copper (Cu) in the alloy is mainly reflected in enhancing the adhesion between the coating and the substrate; copper can form a metallurgical bond with the substrate surface, improve the adhesion of the coating, and prevent the coating from falling off in a high temperature environment.

[0165] Copper (Cu): Copper has a strong lubricating effect and can promote diffusion reactions between metals to form good metallurgical bonding. Copper can fill the tiny gaps between the coating and the substrate, enhance its bonding strength, and reduce the risk of coating peeling and falling off. The addition of copper can also increase the flexibility of the coating and improve the coating's crack resistance.

[0166] Copper forms metallurgical bonding force, making the coating more firmly bonded to the substrate, reducing the possibility of coating peeling under high temperature or harsh environment; under the action of friction or external force, the lubricating effect of copper can reduce the cracking of the coating and extend the service life of the coating.

[0167] 4. Improve oxidation resistance, high temperature resistance, hardness and wear resistance

[0168] Silicon (Si) can improve the oxidation resistance, hardness and wear resistance of the coating through multiple mechanisms, thereby enhancing the overall performance of the coating.

[0169] Silicon (Si): Silicon plays a significant antioxidant role in the alloy. It can form a dense silicon oxide (SiO2) film at high temperatures to protect the coating from oxidation corrosion. The addition of silicon can also increase the hardness of the coating, making it more wear-resistant in a friction environment. Silicon can also enhance the high-temperature stability of the coating and slow down its degradation at high temperatures.

[0170] Silicon oxide film (SiO2) has excellent oxidation resistance and can effectively protect the coating at high temperatures and prevent erosion by oxygen and other harmful gases; the addition of silicon improves the hardness and wear resistance of the alloy coating, allowing the coating to maintain good performance in long-term wear and high-temperature environments.

[0171] 3. Advantages and proof of spherical element configuration of high-entropy alloy coatings resistant to high-temperature sulfur corrosion

[0172] The high entropy alloy coating has a ratio of chromium (Cr), molybdenum (Mo), nickel (Ni), titanium (Ti), aluminum (Al), copper (Cu) and silicon (Si), and each element is arranged in a spherical shape; the application of the spherical configuration in the coating brings the following significant advantages, and its effect is proved by specific principles and experimental results.

[0173] Advantage 1: Improve coating uniformity and structural stability

[0174] Principle: The configuration of spherical particles helps to improve the uniform distribution of elements in the alloy coating; when the elements form spherical particles, these particles can be evenly fused during the melting and coating process, avoiding coating defects caused by uneven particles, such as cracks, pores and other uneven distribution problems; therefore, the coating has better structural stability and can better cope with the test of high temperature and sulfur corrosion.

[0175] Experimental proof: Experiments show that when high-entropy alloy powder exists in the form of spherical particles during thermal spraying, the coating has stronger adhesion, fewer pores, and a denser and more uniform surface than irregular particles; the uniform element distribution greatly reduces the corrosion loss of the coating in a high-temperature sulfur corrosion environment.

[0176] Advantage 2: Enhance the adhesion of the coating

[0177] Principle: The spherical particle shape makes it easier to achieve enhanced surface bonding during coating. In thermal spraying or laser cladding processes, spherical particles can flow better and form a more uniform metallurgical bond with the substrate surface, which enhances the adhesion between the coating and the substrate metal and effectively prevents the coating from falling off.

[0178] Experiments have shown that: in multiple experiments, after the coating adopts the configuration of spherical particles, the bonding force between the coating and the substrate is significantly improved; especially in high temperature and sulfur corrosion environment, the interface strength between the spherical coating and the substrate is increased, which significantly reduces the occurrence of peeling.

[0179] Advantage 3: Improve the thermal stability and high temperature resistance of the coating

[0180] Principle: The coating surface formed by the cladding process of spherical particles is smoother, which can better form a dense oxide film and improve the oxidation resistance of the alloy in a high temperature environment; in addition, spherical particles are easier to melt evenly during heating at high temperatures, reducing the negative impact of temperature fluctuations on coating performance.

[0181] Experimental proof: thermal cycle tests show that the coating formed by spherical particles exhibits strong heat resistance and stability in a high-temperature oxidative environment; its thermal expansion coefficient is relatively close to that of the substrate, which reduces the impact of thermal stress on the coating and extends the service life of the coating.

[0182] Advantage 4: Enhance the coating's anti-sulfur corrosion performance

[0183] Principle: The uniformity of spherical particles helps the coating form a stable protective film in a sulfur corrosion environment; the oxides of chromium, molybdenum, titanium and aluminum can effectively isolate the substrate from the external sulfur source, and the spherical particles can better form a complete oxide film on the coating surface, reducing the corrosion of the coating.

[0184] Experimental proof: Sulfur corrosion tests show that high-entropy alloy coatings with spherical configurations can more effectively prevent sulfide corrosion than particles of other shapes (such as irregular shapes), have stronger resistance to sulfur corrosion, and extend the service life of the coating.

[0185] Advantage 5: Improve the hardness and wear resistance of the coating

[0186] Principle: The spherical particle shape helps to improve the hardness and wear resistance of the coating; since the coating surface is smoother and denser after melting, the hardness of the coating is enhanced, reducing the coating loss caused by wear; in addition, after the density of the coating surface is improved, the friction contact between the particles is reduced, and the wear resistance is stronger.

[0187] Experiments have shown that through friction and wear tests, the hardness of the spherical high-entropy alloy coating is significantly higher than that of the coating using non-spherical particles; the wear rate of the coating is significantly reduced, showing strong wear resistance.

[0188] The high-entropy alloy coating for high-temperature sulfur corrosion of the present invention successfully achieves the comprehensive effects of high temperature resistance, sulfur corrosion resistance, enhanced adhesion, and improved hardness and wear resistance through optimized ratio design and spherical particle process; the spherical particle configuration can improve the uniformity, stability, adhesion, thermal stability, sulfur corrosion resistance, hardness and wear resistance of the coating; combined with advanced thermal spraying, laser cladding or plasma cladding technology, the coating has broad application prospects in high-temperature, corrosive and frictional industrial environments, can significantly extend the life of equipment, reduce maintenance costs, and has extremely high economic benefits and technology promotion value.

[0189] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A high entropy alloy coating resistant to high temperature sulfur corrosion, characterized in that: It includes a mixture of chromium, molybdenum, nickel, titanium, aluminum, copper and silicon; Ratio of high entropy alloy coating: Chromium (Cr): 25%; Molybdenum (Mo): 15%; Nickel (Ni): 20%; Titanium (Ti): 15%; Aluminum (Al): 10%; Copper (Cu): 7.5%; Silicon (Si): 7.5%.

2. The preparation of a high-entropy alloy coating resistant to high-temperature sulfur corrosion according to claim 1, characterized in that: The chromium, molybdenum, nickel, titanium, aluminum, copper and silicon are arranged in a spherical shape.

3. The preparation of a high-entropy alloy coating resistant to high-temperature sulfur corrosion according to claim 2, characterized in that: The chromium, molybdenum, nickel, titanium, aluminum, copper and silicon are atomized by high-pressure gas and formed into spherical powder after cooling.

4. The preparation of a high-entropy alloy coating resistant to high-temperature sulfur corrosion according to claim 1, characterized in that: The spheroidization rates of chromium, molybdenum, nickel, titanium, aluminum, copper and silicon are higher than 95%.

5. The preparation of a high-entropy alloy coating resistant to high-temperature sulfur corrosion according to claim 1, characterized in that: The particle size of the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon particles is 20-105 μm.

6. The method for preparing a high-entropy alloy coating resistant to high-temperature sulfur corrosion according to claim 1, characterized in that: The particle size of the chromium, molybdenum, nickel, titanium, aluminum, copper and silicon particles is 20-48 μm and thermal spraying is used.

7. The method for preparing a high-entropy alloy coating resistant to high-temperature sulfur corrosion according to claim 6, characterized in that: The temperature range of the thermal spraying is 2000-3000°C.

8. The method for preparing a high-entropy alloy coating resistant to high-temperature sulfur corrosion according to claim 5, characterized in that: The particle size of chromium, molybdenum, nickel, titanium, aluminum, copper and silicon is 45-105 μm and is clad by laser or plasma.

9. The method for preparing a high-entropy alloy coating resistant to high-temperature sulfur corrosion according to claim 8, characterized in that: The temperature range of the laser cladding is 1500-2000°C.

10. The method for preparing a high-entropy alloy coating resistant to high-temperature sulfur corrosion according to claim 9, characterized in that: The temperature range of the plasma cladding is 3000-3500°C.

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