Silicon-chromium-titanium-zirconium-hafnium alloy powder and preparation method thereof

Abstract

The invention provides silicon-chromium-titanium-zirconium-hafnium alloy powder and a preparation method thereof, belongs to the technical field of high-temperature coatings, and aims to optimize the comprehensive performance of a niobium alloy spray pipe and increase the use temperature of the niobium alloy spray pipe. The invention provides silicon-chromium-titanium-zirconium-hafnium alloy powder which comprises the following components in percentage by weight: 50 to 73 weight percent of silicon, 15 to 25 weight percent of chromium, 5 to 10 weight percent of titanium, 5 to 10 weight percent of zirconium, 1 to 5 weight percent of hafnium and less than 0.315 weight percent of impurities. According to the high-temperature anti-oxidation coating obtained through the method, a quinary alloy system can generate a high-entropy effect, and the generated composite coating has excellent thermal stability and is good in binding force with a niobium alloy matrix. The alloy system has good high-temperature strength and oxidation resistance, and is suitable for protective coatings of high-temperature parts such as spaceflight rocket engines, aero-engines, nuclear energy equipment and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of metal powders, and in particular to silicon-chromium-titanium-zirconium-hafnium alloy powder and a preparation method thereof. Background Art

[0002] Niobium metal has a melting point of 2468°C. Niobium alloys maintain excellent strength and stability in high-temperature environments, allowing them to withstand the extremely high temperatures generated by rocket engines, ensuring that components do not deform, melt, or fail under extreme conditions. Niobium alloys are used in rocket engine combustion chambers, but they are not resistant to high-temperature oxidation.

[0003] Niobium oxidizes primarily to form niobium pentoxide (Nb2O5). The volume of this oxide is larger than that of metallic niobium, generating significant internal stress within the oxide film. This internal stress can easily lead to rupture of the oxide film. The ruptured oxide film cannot fully cover the niobium alloy surface, preventing oxygen from continuing to react with the metal within, leading to further oxidation. Rapid oxidation reaction rate: The niobium element in niobium alloys is highly chemically active at high temperatures and readily reacts with oxygen. Niobium alloys begin to oxidize rapidly at temperatures exceeding 600°C. Crystal structure and electronic properties: Niobium's crystal structure allows oxygen atoms to easily diffuse into the alloy through interstitial channels, such as the crystal gaps, in the presence of high-temperature oxygen, reacting with niobium atoms. Electronically, the outer electrons of niobium atoms readily interact with those of oxygen atoms at high temperatures, forming chemical bonds and initiating oxidation reactions. Lack of self-repairing ability: Unlike some metals with good oxidation resistance, such as aluminum and chromium, the oxide film formed after oxidation of niobium alloys lacks self-repairing capabilities. When the oxide film is damaged, it cannot quickly repair itself under the influence of the external environment like the oxide films of metals such as aluminum and chromium, and continue to provide protection for the substrate.

[0004] Existing high-temperature oxidation-resistant coatings on niobium alloy surfaces are primarily silicide coatings. Under high-temperature conditions, silicides form a dense, continuous, low-oxygen-permeability oxide film, effectively preventing oxygen from contacting the niobium alloy substrate and providing excellent antioxidant properties. They possess high melting points, hardness, and chemical stability, maintaining structural stability at high temperatures and exhibiting certain thermal shock and corrosion resistance. Si-Cr-Ti or Si-Cr-Fe coatings, prepared using a slurry sintering method, can produce multi-component silicide coatings (Nb, Ti, Cr)Si2 or (Nb, Cr, Fe)Si2, providing effective protection for niobium alloys below 1300°C.

[0005] In the 1970s, Sylavania developed two niobium alloy protective coatings: R512A, primarily composed of Si-20Cr-5Ti, and R512E, primarily composed of Si-20Cr-20Fe. The R512A coating demonstrated a protective lifespan of 100 hours at 1371°C and 1-4 hours at 1649°C. It was successfully applied to the engines of the Apollo lunar module and service module. R512E, capable of withstanding hundreds of thermal shock cycles at 1400°C in air or combustion atmospheres, maintained its remarkably stable performance and was successfully applied to the niobium nozzle protective coating of the F100 rocket engine. However, there remains a need for improved niobium alloy high-temperature protective coatings with higher protection temperatures and longer lifespans. Summary of the Invention

[0006] In response to the above-mentioned problems existing in the prior art, the present invention provides a silicon-chromium-titanium-zirconium-hafnium alloy powder and a preparation method thereof to solve the problem that the high-temperature anti-oxidation coating on the surface of the existing niobium alloy still has room for improvement in terms of high-temperature performance. The use of this alloy powder to prepare a high-temperature anti-oxidation coating can increase the operating temperature of the existing niobium alloy and improve the overall performance of the rocket nozzle.

[0007] The specific content of the invention is as follows: In a first aspect, the present invention provides a silicon-chromium-titanium-zirconium-hafnium alloy powder. Based on 100wt% of the powder, the alloy powder contains 50-73wt% of silicon, 15-25wt% of chromium, 5-10wt% of titanium, 5-10wt% of zirconium, 1-5wt% of hafnium and less than 0.315wt% of impurities.

[0008] Optionally, the alloy powder is irregular or spherical in shape, with a particle size of less than 75 μm, and a bulk density of 1-1.5 g / cm 3 , the tap density is 1.7-1.9g / cm 3 ;Specific surface area 2.5-2.8m 2 / g.

[0009] Optionally, in the alloy powder, the impurities include Fe, Al, Cu, C and O, the Fe content is less than 0.02wt%, the Al content is less than 0.005wt%, the Cu content is less than 0.005wt%, the C content is less than 0.035wt%, and the O content is less than 0.25wt%.

[0010] In a second aspect, the present invention provides a method for preparing the silicon-chromium-titanium-zirconium-hafnium alloy powder according to the first aspect, the method comprising the following steps: S1: Weigh 50-74 wt% of silicon, 15-25 wt% of metallic chromium, 5-10 wt% of metallic titanium, 5-10 wt% of metallic zirconium, and 1-5 wt% of metallic hafnium, add them into an induction melting crucible, and perform vacuum melting to obtain a liquid alloy; S2: atomizing the liquid alloy to obtain a coarse alloy powder, or crushing the liquid alloy by ball milling after casting. S3: Screening the coarse alloy powder to obtain the alloy powder with a particle size less than 75 μm.

[0011] Optionally, in step S1, the vacuum melting is carried out in an argon atmosphere, the melting temperature is 1700-2300°C, and the vacuum degree of the vacuum melting is not higher than 10 -2 Pa.

[0012] Optionally, in step S1 , the purity of the silicon is not less than 5N, and the purity of the metal chromium, metal titanium, metal zirconium and metal hafnium is not less than 3N.

[0013] In a third aspect, the present invention proposes a silicon-chromium-titanium-zirconium-hafnium high-temperature oxidation-resistant coating, which is prepared on the surface of a niobium alloy by a slurry sintering method using the silicon-chromium-titanium-zirconium-hafnium alloy powder described in the first aspect as a raw material; the coating has a thickness of 60-100 μm, and provides effective protection for the niobium alloy material under heating conditions not exceeding 1700°C.

[0014] In a fourth aspect, the present invention provides a method for preparing a silicon-chromium-titanium-zirconium-hafnium high-temperature oxidation-resistant coating, the method comprising the following steps: T1: mixing the silicon-chromium-titanium-zirconium-hafnium alloy powder described in the first aspect with a binder and a solvent in a mass ratio of 4-5:1:3-4 to prepare a slurry; T2: coating the slurry on the surface of the niobium alloy, drying it, and then sintering it to form the high-temperature anti-oxidation coating.

[0015] Optionally, in step T1, the binder is varnish or polyethylene glycol; and the solvent is ethyl acetate, acetone or ethanol.

[0016] Optionally, in step T2, the following specific steps are included: The slurry is sprayed onto the surface of the niobium alloy and vacuum sintered. The sintering temperature is raised from room temperature to 1500-1650°C and kept at 1500-1650°C for 30-60 minutes. The vacuum degree is less than 5×10 -2 Pa.

[0017] Compared with the prior art, the present invention has the following advantages: The present invention provides a silicon-chromium-titanium-zirconium-hafnium alloy powder, a preparation method thereof, and an application thereof, to obtain a high-temperature oxidation-resistant coating. Metal zirconium and metal hafnium elements are added to existing silicon-chromium-titanium alloy powder. Existing niobium alloys such as Nb521 (mainly composed of 5wt% W, 2wt% Mo, and 1wt% Zr, with the balance being Nb) and C103 (10wt% Hf, 1wt% Ti, less than 0.7wt% Zr, less than 0.5wt% Ta, and less than 0.5wt% W, with the balance being Nb) are currently mainly used. Both contain zirconium and hafnium. The silicon-chromium-titanium-zirconium-hafnium alloy powder can improve the bonding strength between the coating and the base niobium alloy. At the same time, Zr and Hf are rare high-melting-point metals, and their oxides ZrO2 and HfO2 have excellent thermal stability and thermal barrier properties, and can form stable oxides (such as ZrO2 and HfO2) on the surface of niobium alloys. Since the melting points of ZrO2 and HfO2 are higher than TiO2, the performance of the original silicon-chromium-titanium alloy powder is further improved.

[0018] If the existing silicon-chromium-titanium alloy powder is mixed with a certain proportion of metal zirconium powder and metal hafnium powder to prepare a silicon-chromium-titanium-zirconium-hafnium high-temperature anti-oxidation coating, it will have better protection effect than the existing coating prepared with only silicon-chromium-titanium powder. However, there are problems of uneven powder distribution and high impurity oxygen content.

[0019] To further optimize the high-temperature oxidation resistance of coatings prepared from SiCrTiZrHf alloy powders, this paper proposes a method for preparing uniform SiCrTiZrHf alloy powders through smelting. This quinary alloy system produces a "high entropy effect," enhancing solid solution strengthening. After smelting, a uniform and stable SiCrTiZrHf alloy powder is obtained, improving the material's overall mechanical properties and thermal stability. This alloy system exhibits excellent high-temperature strength and oxidation resistance, making it suitable for protective coatings on high-temperature components such as rocket engine nozzles, aircraft engines, and nuclear power equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A flow chart of a method for preparing silicon-chromium-titanium-zirconium-hafnium alloy powder provided in an embodiment of the present invention is shown; Figure 2 A flow chart of a method for preparing a silicon-chromium-titanium-zirconium-hafnium high-temperature oxidation-resistant coating provided by an embodiment of the present invention is shown; Figure 3A scanning electron microscope image of a silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by crushing and ball milling according to an embodiment of the present invention is shown; Figure 4 The scanning electron microscope images of the silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by crushing and ball milling according to the embodiment of the present invention at different magnifications are shown; Figure 5 A scanning electron microscope image of a silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by gas atomization according to an embodiment of the present invention is shown; Figure 6 The scanning electron microscope images of the silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by gas atomization according to the embodiment of the present invention at different magnifications are shown; Figure 7 The figure shows a silicon-chromium-titanium-zirconium-hafnium high-temperature oxidation-resistant coating provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present invention and its application or use. Based on the embodiments of the present invention, any product that is identical or similar to the present invention and is obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts falls within the scope of protection of the present invention. In addition, all other embodiments obtained by ordinary technicians in this field without carrying out creative work fall within the scope of protection of the present invention.

[0023] Where specific experimental steps or conditions are not specified in the examples, the conventional experimental steps or conditions described in the prior art in the art may be used. Reagents and other instruments used, for which the manufacturer is not specified, are commercially available conventional reagent products. Furthermore, the accompanying drawings are merely schematic illustrations of embodiments of the present invention and are not necessarily drawn to scale. Identical reference numerals in the figures denote identical or similar parts, and their repeated descriptions will be omitted. Some block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0024] Technologies, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies, methods, and equipment should be considered part of the description of the present invention.

[0025] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0026] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Before describing in detail the silicon-chromium-titanium-zirconium-hafnium alloy powder provided by the present invention, its preparation method, and application, it is necessary to describe the related technologies as follows: Niobium metal has a melting point of 2468°C. Niobium alloys maintain excellent strength and stability in high-temperature environments, allowing them to withstand the extremely high temperatures generated by rocket engines, ensuring that components do not deform, melt, or fail under extreme conditions. Niobium alloys are used in rocket engine combustion chambers, but they are not resistant to high-temperature oxidation.

[0028] Niobium oxidizes primarily to form niobium pentoxide (Nb2O5). The volume of this oxide is larger than that of metallic niobium, generating significant internal stress within the oxide film. This internal stress can easily lead to rupture of the oxide film. The ruptured oxide film cannot fully cover the niobium alloy surface, preventing oxygen from continuing to react with the metal within, leading to further oxidation. Rapid oxidation reaction rate: The niobium element in niobium alloys is highly chemically active at high temperatures and readily reacts with oxygen. Niobium alloys begin to oxidize rapidly at temperatures exceeding 600°C. Crystal structure and electronic properties: Niobium's crystal structure allows oxygen atoms to easily diffuse into the alloy through interstitial channels, such as the crystal gaps, in the presence of high-temperature oxygen, reacting with niobium atoms. Electronically, the outer electrons of niobium atoms readily interact with those of oxygen atoms at high temperatures, forming chemical bonds and initiating oxidation reactions. Lack of self-repairing ability: Unlike some metals with good oxidation resistance, such as aluminum and chromium, the oxide film formed after oxidation of niobium alloys lacks self-repairing capabilities. When the oxide film is damaged, it cannot quickly repair itself under the influence of the external environment like the oxide films of metals such as aluminum and chromium, and continue to provide protection for the substrate.

[0029] Existing high-temperature oxidation-resistant coatings on niobium alloy surfaces are primarily silicide coatings. Under high-temperature conditions, silicides form a dense, continuous, low-oxygen-permeability oxide film, effectively preventing oxygen from contacting the niobium alloy substrate and providing excellent antioxidant properties. They possess high melting points, hardness, and chemical stability, maintaining structural stability at high temperatures and exhibiting certain thermal shock and corrosion resistance. Si-Cr-Ti or Si-Cr-Fe coatings, prepared using a slurry sintering method, can produce multi-component silicide coatings (Nb, Ti, Cr)Si2 or (Nb, Cr, Fe)Si2, providing effective protection for niobium alloys below 1300°C.

[0030] In the 1970s, Sylavania developed two niobium alloy protective coatings: R512A, primarily composed of Si-20Cr-5Ti, and R512E, primarily composed of Si-20Cr-20Fe. The R512A coating demonstrated a protective lifespan of 100 hours at 1371°C and 1-4 hours at 1649°C. It was successfully applied to the engines of the Apollo lunar module and service module. R512E, capable of withstanding hundreds of thermal shock cycles at 1400°C in air or combustion atmospheres, maintained its remarkably stable performance and was successfully applied to the niobium nozzle protective coating of the F100 rocket engine. However, there remains a need for improved niobium alloy high-temperature protective coatings with higher protection temperatures and longer lifespans.

[0031] In order to enable those skilled in the art to more clearly understand the present invention, the silicon-chromium-titanium-zirconium-hafnium alloy powder, its preparation method and application according to the present invention are now described in detail through the following examples.

[0032] In a first aspect, the present invention provides a silicon-chromium-titanium-zirconium-hafnium alloy powder, which, based on 100 wt%, contains 50-73 wt% silicon, 15-25 wt% chromium, 5-10 wt% titanium, 5-10 wt% zirconium, 1-5 wt% hafnium and less than 0.315 wt% impurities.

[0033] Using this technical solution, the quinary alloy system can produce a "high entropy effect," enhancing solid solution strengthening and improving the material's overall mechanical properties and thermal stability. This alloy system possesses excellent high-temperature strength and oxidation resistance, making it suitable for protective coatings on high-temperature components such as aircraft engines and nuclear power equipment.

[0034] In some embodiments, the alloy powder is irregular or spherical in shape, with a particle size of less than 75 μm; the alloy powder has a bulk density of 1-1.5 g / cm 3 , the tap density is 1.7-1.9g / cm 3 ;Specific surface area 2.5-2.8m 2 / g.

[0035] Using this technical solution, fine powders facilitate slurry dispersion and spray uniformity, making them suitable for thermal spraying or vacuum sintering film formation. Spherical powders are more suitable for automated spraying and powder conveying, while irregularly shaped powders offer stronger adhesion, facilitating coating bonding. Moderate bulk and tap densities indicate good filling properties, facilitating subsequent sintering densification. Excessively high specific surface area may lead to agglomeration, while too low a specific surface area can negatively impact reactivity. This range balances powder flowability and sintering activity.

[0036] In some embodiments, in addition to the impurities introduced in the raw materials, some impurities are also introduced into the alloy powder during the preparation process of the alloy powder. It is necessary to control the total content of major impurities to be less than 0.315wt%. The impurities include Fe, Al, Cu, C and O. The Fe content is less than 0.02wt%, the Al content is less than 0.005wt%, the Cu content is less than 0.005wt%, the C content is less than 0.035wt%, and the O content is less than 0.25wt%.

[0037] With this technology, impurity elements such as Fe and Al can promote unintended phase transformations or the formation of brittle compounds, degrading material properties. Carbon and oxygen can easily form inclusions, affecting density and the quality of the antioxidant film. Low impurities contribute to a more uniform microstructure and prevent localized corrosion or oxidation failure.

[0038] Secondly, Figure 1 FIG. 1 shows a flow chart of a method for preparing silicon-chromium-titanium-zirconium-hafnium alloy powder according to an embodiment of the present invention. Figure 1 As shown, the present invention also proposes a method for preparing the silicon-chromium-titanium-zirconium-hafnium alloy powder according to the first aspect, the method comprising the following steps: S1: Weigh 50-74 wt% of silicon, 15-25 wt% of metallic chromium, 5-10 wt% of metallic titanium, 5-10 wt% of metallic zirconium, and 1-5 wt% of metallic hafnium, add them into an induction melting crucible, and perform vacuum melting to obtain a liquid alloy; S2: atomizing the liquid alloy to obtain a coarse alloy powder, or crushing the liquid alloy by ball milling after casting. S3: Screening the coarse alloy powder to obtain the alloy powder with a particle size less than 75 μm.

[0039] This technical solution is highly efficient and controllable. Induction melting allows for rapid heating in an inert atmosphere, preventing oxidation. Gas atomization produces fine, uniform particles, while ball milling is suitable for crushing large ingots, flexibly adapting to varying production scales. The entire process is conducted in a closed environment, maintaining alloy composition consistency and minimizing compositional segregation and contamination.

[0040] Figure 3-6 The scanning electron microscope images of silicon-chromium-titanium-zirconium-hafnium alloy powders obtained by different powder making methods provided in the embodiments of the present invention at different magnifications are shown. Figure 3 A scanning electron microscope image of a silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by crushing and ball milling according to an embodiment of the present invention is shown; Figure 4 A scanning electron microscope image at another magnification of the silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by crushing and ball milling according to an embodiment of the present invention is shown; Figure 5 A scanning electron microscope image of a silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by gas atomization according to an embodiment of the present invention is shown; Figure 6 FIG2 shows a scanning electron microscope image of the silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by gas atomization provided in an embodiment of the present invention at another magnification; Figure 3 and 4 As shown in the figure, the powder obtained by crushing and ball milling has irregular particle shape, showing polygonal or block structure, relatively uniform particle distribution, size less than 40μm, and no obvious aggregation or separation phenomenon. Figure 5 and 6 As shown, the powder obtained by aerosol pulverization has a clear spherical or nearly spherical structure, a smooth and uniform surface, a relatively uniform particle distribution, a size of less than 70 μm, no obvious aggregation or separation phenomenon, and shows good dispersibility.

[0041] In some embodiments, in S1, the vacuum melting is performed in an argon atmosphere, the melting temperature is 1700-2300°C, and the vacuum degree of the vacuum melting is not higher than 10 -2 Pa.

[0042] With this technical solution, during the smelting process, metals are very likely to react with oxygen, water vapor, nitrogen, etc., forming unintended products such as oxides and nitrides. Using argon inert protection + high vacuum environment can significantly reduce the partial pressure of active gases in the air; inhibit the oxidation, nitridation and carburization of metal elements; reduce the formation of inclusions, and improve material purity. A purer and more uniform alloy structure is obtained. High vacuum conditions (≤10 -2 Argon (Pa) helps lower the boiling point of the material, making it easier for low-boiling-point impurities (such as Pb, Zn, Sn, and Bi) to volatilize and be extracted, further purifying the material. As an inert gas, argon provides a certain stirring effect during the melting process, helping to evenly mix the melt. Furthermore, under vacuum conditions, it effectively removes dissolved gases (such as hydrogen and oxygen) from the melt, preventing defects such as porosity and looseness in the casting. This improves the density and microstructural uniformity of the casting, enhancing mechanical properties. The melting point of silicon (Si) is 1414°C; the melting point of chromium (Cr) is 1907°C; the melting point of titanium (Ti) is 1668°C; the melting point of zirconium (Zr) is 1855°C; and the melting point of hafnium (Hf) is 2233°C. The alloy system can lower the melting point, and the melting temperature is selected between 1700-2300°C to ensure that the above alloy components are fully melted.

[0043] In some embodiments, in S1, the purity of the silicon is not less than 5N, and the purity of the metal chromium, metal titanium, metal zirconium, and metal hafnium is not less than 3N.

[0044] With this technical solution, high-purity raw materials are the prerequisite for obtaining high-performance alloy powder, ensuring that the total amount of impurities in the finished product is less than 0.315% is achieved.

[0045] In some embodiments, in S2, the gas atomization powdering uses argon as the impact fluid, the gas pressure is 5-10 MPa, and the specific pressure is adjusted according to the actual powder particle size, and is cooled at a rate of 104-105 K / s to obtain a coarse alloy powder.

[0046] This technical solution, using high-purity argon as the atomizing medium, provides a low-oxygen, impurity-free environment throughout the entire process. This effectively prevents reactive metals (such as titanium, zirconium, and hafnium) from reacting with oxygen or other reactive gases in the air, reducing the presence of oxides and other impurities. Appropriate gas pressure and flow rate facilitate the formation of nearly spherical powder particles, producing fine particles with a narrow particle size distribution and improving powder fluidity. The argon gas allows for rapid cooling, promoting grain refinement and enhancing the mechanical properties of the powder material.

[0047] In some embodiments, in the crushing ball milling, a jaw crusher or a hammer crusher is first used to crush the smelted alloy block into particles of 5-20 mm, and then the particles are ball milled for 8-12 hours in a planetary ball mill or a vibrating ball mill at a ball-to-material ratio of 5-10:1 and a rotation speed of 200-600 rpm to obtain a crude alloy powder.

[0048] This technical solution uses a jaw crusher or hammer crusher to quickly and effectively reduce the size of the raw materials, significantly shortening the time required for subsequent fine grinding. Ball milling allows for efficient fine grinding in a shorter time. By performing coarse crushing followed by fine grinding, the particle size distribution of the final powder can be better controlled. The initial crushing ensures consistent material size, which helps to produce more uniform powder particles during subsequent ball milling.

[0049] Thirdly, as Figure 6 As shown, the present invention proposes a silicon-chromium-titanium-zirconium-hafnium high-temperature oxidation-resistant coating, which is prepared on the surface of a niobium alloy by a slurry sintering method using the silicon-chromium-titanium-zirconium-hafnium alloy powder described in the first aspect as a raw material; the coating has a thickness of 60-100 μm, and provides effective protection for the niobium alloy material under heating conditions not exceeding 1700°C.

[0050] Using this technical solution, Si forms a dense SiO2 protective film at high temperatures, which is fluid and can fill gaps in the coating. Cr forms a dense Cr2O3 protective film at high temperatures, enhancing oxidation resistance. Ti, Zr, and Hf, as high-melting-point metals, possess excellent thermal stability and can form stable oxides (such as TiO2, ZrO2, and HfO2) on their surfaces, providing thermal barrier properties and further enhancing oxidation resistance and corrosion resistance. This quinary alloy system can produce a "high entropy effect," enhancing solid solution strengthening and improving the material's overall mechanical properties and thermal stability. This alloy system possesses excellent high-temperature strength and oxidation resistance, making it suitable for protective coatings of high-temperature components such as aircraft engines and nuclear power equipment. Existing niobium alloy high-temperature oxidation-resistant protective coatings generally provide long-term protection at temperatures below 1400°C, while the present invention's high-temperature oxidation-resistant protective coating can provide extended protection at temperatures between 1400°C and 1700°C.

[0051] In a fourth aspect, the present invention provides a method for preparing a silicon-chromium-titanium-zirconium-hafnium high-temperature oxidation-resistant coating, the method comprising the following steps: T1: mixing the silicon-chromium-titanium-zirconium-hafnium alloy powder described in the first aspect with a binder and a solvent in a mass ratio of 4-5:1:3-4 to prepare a slurry; T2: coating the slurry on the surface of the niobium alloy, drying it, and then sintering it to form the high-temperature anti-oxidation coating.

[0052] This technical solution produces a slurry with excellent dispersibility and adhesion. The binder and alloy powders are well compatible, resulting in a uniform and stable slurry with strong adhesion after spraying. Sintering ensures full densification and alloying. High-temperature treatment promotes diffusion bonding between powder particles, forming a dense, continuous coating and enhancing the integrity of the anti-oxidation film. The niobium alloy maintains structural stability even at high temperatures, and this process matches its thermal expansion coefficient well, preventing cracking or shedding.

[0053] In some embodiments, in step T1, the binder is varnish or polyethylene glycol; and the solvent is ethyl acetate, acetone, or ethanol.

[0054] The technical solution is environmentally friendly and easy to construct. The selected solvents are all common organic solvents with fast volatility and low toxicity, which are suitable for industrial applications. The binder is reasonably selected and does not affect the subsequent sintering process.

[0055] In some embodiments, step T2 includes the following specific steps: The slurry is sprayed onto the surface of the niobium alloy and vacuum sintered. The sintering temperature is raised from room temperature to 1500-1650°C and kept at 1500-1650°C for 30-60 minutes. The vacuum degree is less than 5×10 -2 Pa.

[0056] The adoption of this technical solution can effectively inhibit secondary oxidation, and sintering in a vacuum environment can minimize the participation of oxygen and avoid the formation of holes or non-dense oxide layers inside the coating.

[0057] Example 1 62wt% silicon, 20wt% chromium, 7.5wt% titanium, 7.5wt% zirconium and 3wt% hafnium were weighed and added into an induction melting crucible at a temperature of 1950-2050℃ and a vacuum degree of 0.5×10 -2 Pa under vacuum melting conditions to obtain a liquid alloy; after the liquid alloy ingot is cast, a jaw crusher is used to crush the molten alloy block into particles of 5-20 mm, and then the molten alloy block is ball-milled in a planetary ball mill at a ball-to-material ratio of 7:1 and a rotation speed of 400 rpm for 10 hours to obtain a crude alloy powder; the crude alloy powder is sieved to obtain the alloy powder with a particle size of less than 75 μm. The silicon-chromium-titanium-zirconium-hafnium alloy powder is mixed with polyethylene glycol and ethyl acetate in a mass ratio of 4.5:1:3.5 to prepare a slurry; the slurry is coated on the surface of the niobium alloy, dried, and then heated from room temperature to 1500-1650°C, kept at 1500-1650°C for 45 minutes, and the vacuum degree is 1×10 -2 Pa, forming the high temperature anti-oxidation coating.

[0058] Figure 3 A scanning electron microscope image of a silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by crushing and ball milling according to an embodiment of the present invention is shown; Figure 4 The scanning electron microscope images of the silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by crushing and ball milling provided in the embodiment of the present invention at different magnifications are shown; Figure 3 and 4 As shown in the figure, the powder is obtained by crushing and ball milling. The particles are irregular in shape, showing a polygonal or blocky structure. The particles are relatively evenly distributed, with a size of less than 40 μm, and there is no obvious aggregation or separation phenomenon.

[0059] Example 2 62wt% silicon, 20wt% chromium, 7.5wt% titanium, 7.5wt% zirconium and 3wt% hafnium were weighed and added into an induction melting crucible at a temperature of 1950-2050℃ and a vacuum degree of 0.5×10 -2Pa, vacuum melting is performed to obtain a liquid alloy; the liquid alloy is atomized and powdered using argon as an impact fluid, the argon gas pressure is 7MPa, and the aerosol particles are cooled at a rate of 104-105K / s to obtain a crude alloy powder; the crude alloy powder is sieved to obtain the alloy powder with a particle size of less than 75μm. The silicon-chromium-titanium-zirconium-hafnium alloy powder is mixed with polyethylene glycol and ethyl acetate in a mass ratio of 4.5:1:3.5 to form a slurry; the slurry is coated on the surface of the niobium alloy, dried, and then heated from room temperature to 1500-1650℃, kept at 1500-1650℃ for 45 minutes, and the vacuum degree is 1×10 -2 Pa, forming the high temperature anti-oxidation coating.

[0060] Figure 5 A scanning electron microscope image of a silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by gas atomization pulverization according to an embodiment of the present invention is shown; Figure 6 The scanning electron microscope images of the silicon-chromium-titanium-zirconium-hafnium alloy powder obtained by gas atomization pulverization provided in the embodiment of the present invention at different magnifications are shown; Figure 5 and 6 As shown in the figure, the powder obtained by aerosol pulverization has a clear spherical or nearly spherical structure, a smooth and uniform surface, a relatively uniform particle distribution, a size of less than 70 μm, no obvious aggregation or separation phenomenon, and good dispersibility.

[0061] Example 3 55wt% silicon, 25wt% chromium, 10wt% titanium, 6wt% zirconium and 4wt% hafnium were weighed and added into an induction melting crucible at a temperature of 1950-2050℃ and a vacuum degree of 0.5×10 -2 Pa, vacuum melting is performed to obtain a liquid alloy; after the liquid alloy ingot is cast, a jaw crusher is used to crush the molten alloy block into particles of 5-20 mm, and then the molten alloy block is ball-milled for 10 hours in a planetary ball mill at a ball-to-material ratio of 7:1 and a rotation speed of 400 rpm to obtain a crude alloy powder; the crude alloy powder is sieved to obtain the alloy powder with a particle size of less than 75 μm. The silicon-chromium-titanium-zirconium-hafnium alloy powder is mixed with varnish and acetone in a mass ratio of 4.5:1:3.5 to form a slurry; the slurry is applied to the surface of the niobium alloy, dried, and then heated from room temperature to 1500-1650°C, kept at 1500-1650°C for 100 minutes, and the vacuum degree is 1×10 -2 Pa, forming the high temperature anti-oxidation coating.

[0062] Example 4 70wt% silicon, 15wt% chromium, 6wt% titanium, 6wt% zirconium and 3wt% hafnium were weighed and added into an induction melting crucible at a temperature of 1950-2050℃ and a vacuum degree of 0.5×10 -2 Pa, vacuum melting is performed to obtain a liquid alloy; the liquid alloy is atomized and powdered using argon as an impact fluid, the argon gas pressure is 7MPa, and the aerosol particles are cooled at a rate of 104-105K / s to obtain a crude alloy powder; the crude alloy powder is sieved to obtain the alloy powder with a particle size of less than 75μm. The silicon-chromium-titanium-zirconium-hafnium alloy powder is mixed with varnish and ethyl acetate in a mass ratio of 4.5:1:3.5 to form a slurry; the slurry is applied to the surface of the niobium alloy, dried, and then heated from room temperature to 1500-1650℃, kept at 1500-1650℃ for 120 minutes, and the vacuum degree is 1×10 -2 Pa, forming the high temperature anti-oxidation coating.

[0063] In order to evaluate the stability and protective performance of the high-temperature oxidation-resistant coating prepared from the silicon-chromium-titanium-zirconium-hafnium alloy powder of the present invention under extremely high temperature conditions, a high-temperature oxidation test was conducted using the following test method: 1. Test conditions Test temperature: 1700°C; Holding time: 10 hours; Atmosphere: Static air atmosphere (i.e., exposed to air at normal pressure without airflow control); Heating method: Electric heating (clamping at both ends); The sample is installed between graphite electrodes and directly heated by electric current; Heating rate: Controlled at 5-10°C / min to avoid thermal shock; The temperature is finally raised to 1700°C and maintained at a constant temperature for 10 hours; Temperature measurement method: Infrared thermometer (non-contact), with a temperature measurement range of 0-2000°C and an accuracy level of not less than ±2°C; The installation position should avoid reflection interference from the heating furnace cavity to ensure accurate measurement.

[0064] 2. Sample preparation: Substrate material: niobium alloy; Coating preparation: Using the high-temperature antioxidant coating preparation method provided in Example 2, spray the slurry on the substrate surface and then vacuum sinter it to form a continuous coating; Specimen shape and size: Niobium alloy with a length of not less than 30 mm and a moderate width for easy clamping and temperature measurement; Before testing, the specimen surface must be cleaned to remove oil stains and impurity particles to ensure test consistency.

[0065] 3. Test device: A high-temperature electric heating furnace system is used, equipped with: a graphite fixture for fixing the sample; an infrared thermometer to monitor the temperature of the central area of the sample in real time; a temperature control system to achieve precise heating and constant temperature control; an observation window or camera system can be used to observe coating changes in situ.

[0066] 4. Test steps Clamp both ends of the sample coated with the high-temperature anti-oxidation coating on a heating device to ensure good conductivity; start the heating program and raise the temperature to 1700°C at a set rate; maintain a constant temperature of 1700°C for 10 hours; continuously monitor the sample temperature using an infrared thermometer during the experiment and record the temperature; naturally cool to room temperature after the experiment; perform a visual inspection of the sample, focusing on observing whether the coating has any failure phenomena such as shedding, cracking, and blistering.

[0067] Whether the coating is completely attached to the substrate surface without obvious peeling or cracking; determine whether the substrate is oxidized through metallographic or composition analysis.

[0068] A 60-100 μm high-temperature oxidation-resistant coating was prepared on the surface of the sample using the preparation methods of Examples 1-4. Following the aforementioned testing procedures, the sample coating remained adhered to the surface of the sample after heating at 1700°C for 10 hours, without any failure phenomena such as shedding, cracking, or bubbling. in, Figure 7 The silicon-chromium-titanium-zirconium-hafnium high-temperature oxidation-resistant coating provided in Example 2 is heated to 1700°C in an air atmosphere for 10 hours. Figure 7 As shown, the sample coating did not fail, such as falling off or cracking, and the base material showed no obvious signs of oxidation, indicating that the high-temperature anti-oxidation coating has excellent high-temperature stability and good interface bonding ability. In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like are intended to mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0069] For simplicity of description, the method embodiments are described as a series of actions. However, those skilled in the art should be aware that the present invention is not limited by the order of the actions described, as certain steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also be aware that the embodiments described in this specification are preferred embodiments, and the actions and components involved are not necessarily required for the present invention.

[0070] The above is a detailed introduction to a silicon-chromium-titanium-zirconium-hafnium alloy powder provided by the present invention, its preparation method and application. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A silicon-chromium-titanium-zirconium-hafnium alloy powder, characterized in that: Based on 100wt% of the powder, the alloy powder contains 50-73wt% of silicon, 15-25wt% of chromium, 5-10wt% of titanium, 5-10wt% of zirconium, 1-5wt% of hafnium and less than 0.315wt% of impurities.

2. The silicon-chromium-titanium-zirconium-hafnium alloy powder according to claim 1, characterized in that: The alloy powder is irregular or spherical in shape, with a particle size of less than 75 μm, and a bulk density of 1-1.5 g / cm 3 , the tap density is 1.7-1.9g / cm 3 ;Specific surface area 2.5-2.8m 2 / g.

3. The silicon-chromium-titanium-zirconium-hafnium alloy powder according to claim 1, characterized in that: In the alloy powder, the impurities include Fe, Al, Cu, C and O, the Fe content is less than 0.02wt%, the Al content is less than 0.005wt%, the Cu content is less than 0.005wt%, the C content is less than 0.035wt%, and the O content is less than 0.25wt%.

4. A method for preparing the silicon-chromium-titanium-zirconium-hafnium alloy powder according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: S1: Weigh 50-74 wt% of silicon, 15-25 wt% of metallic chromium, 5-10 wt% of metallic titanium, 5-10 wt% of metallic zirconium, and 1-5 wt% of metallic hafnium, add them into an induction melting crucible, and perform vacuum melting to obtain a liquid alloy; S2: atomizing the liquid alloy to obtain a coarse alloy powder, or crushing the liquid alloy by ball milling after casting. S3: Screening the coarse alloy powder to obtain the alloy powder with a particle size less than 75 μm.

5. The method for preparing silicon-chromium-titanium-zirconium-hafnium alloy powder according to claim 4, characterized in that: In step S1, the vacuum melting is carried out in an argon atmosphere, the melting temperature is 1700-2300°C, and the vacuum degree of the vacuum melting is not higher than 10 -2 Pa.

6. The method for preparing silicon-chromium-titanium-zirconium-hafnium alloy powder according to claim 4, characterized in that: In step S1 , the purity of the silicon is not less than 5N, and the purity of the metal chromium, metal titanium, metal zirconium and metal hafnium is not less than 3N.

7. A silicon-chromium-titanium-zirconium-hafnium high-temperature oxidation-resistant coating, characterized in that: The coating is prepared on the surface of the niobium alloy by a slurry sintering method using the silicon-chromium-titanium-zirconium-hafnium alloy powder according to any one of claims 1 to 3 as a raw material; the coating has a thickness of 60-100 μm, and the coating provides effective protection for the niobium alloy material under heating conditions not exceeding 1700°C.

8. A method for preparing a silicon-chromium-titanium-zirconium-hafnium high-temperature oxidation-resistant coating, characterized in that: The method comprises the following steps: T1: mixing the silicon-chromium-titanium-zirconium-hafnium alloy powder according to any one of claims 1 to 3 with a binder and a solvent in a mass ratio of 4-5:1:3-4 to prepare a slurry; T2: coating the slurry on the surface of the niobium alloy, drying it, and then sintering it to form the high-temperature anti-oxidation coating.

9. The method for preparing silicon-chromium-titanium-zirconium-hafnium alloy powder according to claim 8, characterized in that: In step T1, the binder is varnish or polyethylene glycol; the solvent is ethyl acetate, acetone or ethanol.

10. The method for preparing silicon-chromium-titanium-zirconium-hafnium alloy powder according to claim 8, characterized in that: In step T2, the following specific steps are included: The slurry is sprayed onto the surface of the niobium alloy and vacuum sintered. The sintering temperature is raised from room temperature to 1500-1650°C and kept at 1500-1650°C for 30-60 minutes. The vacuum degree is less than 5×10 -2 Pa.

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