Laser heat protection high-entropy oxide coating and method of making same

Abstract

Embodiments of the present application provide a kind of laser heat protection high-entropy oxide coating and its preparation method. Applied to involve laser protection material technical field, method includes: according to quality proportioning, the raw material powder is weighed;The well weighed powder is placed in horizontal ball mill and stirred, after mixing uniformly, it is placed in blast drying oven and is dried, after drying is completed, it is placed in high temperature box muffle furnace and is carried out solid phase synthesis, with furnace cooling to room temperature after, mixed powder, deionized water and binder are broken using horizontal ball mill, after the material is broken is refined using vertical sand mill, and mixed powder is obtained;The mixed powder is placed in blast drying oven and is dried, to obtain the powder for spraying;The powder for spraying after drying is loaded into powder feeder;Adopting plasma physical vapor deposition method is sprayed on the surface of the sample to be sprayed substrate coating.The heat protection coating of the present application has good effect on laser irradiation heat protection, with the characteristics of high reflection, low absorption, simple structure, wide application range.

Description

Technical Field

[0001] This invention relates to the field of laser protection materials technology, and in particular to a high-entropy oxide coating for laser thermal protection and its preparation method. Background Technology

[0002] One of the main applications of laser technology is in various laser weapons that use laser beams as energy carriers; this is a high-tech method that utilizes the enormous energy carried by high-brightness, high-intensity laser beams to destroy or kill targets. High-energy laser beams cause complex damage and destruction effects on irradiated targets, resulting in instantaneous damage and destruction.

[0003] Existing laser protective coatings are typically ablation-resistant, but their thermal protection effectiveness decreases significantly after reaching thermal equilibrium over a certain period, and they also suffer from poor stability and are prone to peeling. Therefore, providing a protective coating with superior thermal protection and better stability is an urgent problem to be solved. By integrating existing yttrium-stabilized zirconia (YSZ) ceramic coatings, a novel high-entropy oxide coating material will be developed, which will effectively improve the laser protection capabilities of weapon platforms and payloads, achieving effective protection against high-energy laser irradiation. Summary of the Invention

[0004] This invention provides a high-entropy oxide coating for laser thermal protection and its preparation method, which solves the technical problems of existing laser protective coatings, which are usually ablation-resistant, whose thermal protection effect decreases significantly after reaching thermal equilibrium over a certain period of time, and which have poor stability and are prone to peeling off.

[0005] According to a first aspect of the present invention, a laser thermal protection high-entropy oxide coating is provided, which belongs to a high-entropy rare earth oxide ceramic powder material with a multi-component disordered single-phase structure, and the surface average reflectivity of the coating is higher than 75%.

[0006] High-entropy rare earth oxide ceramic powder materials in equal mass ratios include yttrium, gadolinium, erbium, ytterbium, and lutetium.

[0007] Of these, yttrium, gadolinium, erbium, ytterbium, and lutetium each account for 20% of the total mass.

[0008] According to a second aspect of the present invention, a method for preparing a laser-thermal-protective high-entropy oxide coating is provided, comprising: Weigh the raw material powder according to the mass ratio; The proportioned powder is placed in a horizontal ball mill and stirred until evenly mixed. Then it is placed in a forced-air drying oven for drying. The dried powder was placed in a high-temperature box-type muffle furnace for high-temperature sintering solid-phase synthesis, and then cooled to room temperature with the furnace. The mixed powder, deionized water, and binder are placed into a horizontal ball mill for crushing; The crushed material is put into a vertical sand mill for further crushing and refining to obtain a mixed powder; Dry the spray powder using a forced-air drying oven, and then load the dried spray powder into the powder feeder; The thermal protective coating was prepared by spraying the material onto the surface of the substrate sample using plasma physical vapor deposition (PS-PVD).

[0009] Compared with existing technologies, the advantages and positive effects of this invention are: Compared with traditional metal coating materials, this invention uses ceramic materials with high melting points and excellent chemical stability, overcoming the disadvantages of low melting points and easy oxidation at high temperatures of metal materials, while maintaining high laser reflectivity. The high temperature and relatively concentrated heat of the plasma flame can melt most high-melting-point and high-hardness powder materials. Using plasma spraying technology ensures that the sprayed particles are fully melted during the spraying process, resulting in effective and tight bonding between the layered structures within the coating, reducing the formation of pores and lowering the surface roughness. Furthermore, the use of inert gases (He, Ar, N2, or mixtures thereof) as the working gas for plasma spraying effectively protects the workpiece surface and the sprayed powder particles from oxidation in the high-temperature environment during spraying, maintaining good mechanical properties.

[0010] The high-entropy oxide coating for laser protection and its preparation method proposed in this invention have the advantages of simple preparation method, significant protection effect and wide applicability. It can be widely used for laser protection of weapons and payload platforms such as spacecraft, missiles and hypersonic platforms.

[0011] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0012] The above and other features, advantages, and aspects of the various embodiments of the present invention will become more apparent from the accompanying drawings and the following detailed description. The drawings are provided for a better understanding of the invention and are not intended to limit the invention. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein: Figure 1 A flowchart illustrating a method for preparing a laser thermal protection high-entropy oxide coating according to an embodiment of the present invention is shown; Figure 2 A schematic diagram illustrating a laser thermal protection high-entropy oxide coating and its preparation method according to an embodiment of the present invention is shown. Figure 3 A schematic diagram of thermal shock according to an embodiment of the present invention is shown; Figure 4 A schematic diagram showing a comparison of thermal shock results according to an embodiment of the present invention is provided. Figure 5 A schematic diagram of laser irradiation before the present invention is shown; Figure 6 A schematic diagram of laser irradiation according to an embodiment of the present invention is shown; Figure 7 A schematic diagram of laser irradiation according to an embodiment of the present invention is shown. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0015] The laser thermal protection high-entropy oxide coating in this embodiment of the invention belongs to a high-entropy rare earth oxide ceramic powder material with a multi-component disordered single-phase structure, and the average surface reflectivity of the coating is higher than 75%.

[0016] High-entropy rare earth oxide ceramic powder materials include yttrium (Y), gadolinium (Gd), erbium (Er), ytterbium (Yb), and lutetium (Lu).

[0017] Among them, yttrium (Y), gadolinium (Gd), erbium (Er), ytterbium (Yb), and lutetium (Lu) each account for 20% of the mass.

[0018] Figure 1 This diagram illustrates a process flow chart of a method 100 for preparing a laser thermal protection high-entropy oxide coating according to an embodiment of the present invention. The principle is described in the appendix. Figure 2 ,like Figure 1 As shown, method 100 includes: S110: Weigh the raw material powder according to the mass ratio.

[0019] S120: Put the proportioned powder into a horizontal ball mill and stir. After mixing evenly, place it in a forced-air drying oven for drying.

[0020] S130: The dried powder is placed in a high-temperature box-type muffle furnace for high-temperature sintering solid-phase synthesis, and then cooled to room temperature with the furnace.

[0021] It should be noted that, in the embodiments, the sintering temperature is 1500℃ and the sintering time is 3 to 5 hours, forming a single-phase defect fluorite (disordered) structure with a grain size of 100 to 200 nm, and the five rare earth elements are uniformly distributed.

[0022] S140: The mixed powder, deionized water and binder are put into a horizontal ball mill for crushing.

[0023] It should be noted that, in the embodiments, the mass of the binder is 3% to 5% of the mass of the mixed powder.

[0024] S150: The crushed material is put into a vertical sand mill for further crushing and refining to obtain a mixed powder.

[0025] S160: Use a blower oven to dry the powder for spraying, and then load the dried powder for spraying into the powder feeder.

[0026] S170: The thermal protective coating is prepared by spraying the material onto the surface of the substrate sample using plasma physical vapor deposition (PS-PVD).

[0027] It should be noted that, in the embodiments, plasma physical vapor deposition technology encompasses plasma spraying and electron beam physical vapor deposition processes, which can uniformly prepare coatings around the surface of parts with complex shapes and achieve high deposition rates.

[0028] In the plasma physical vapor deposition spraying process, the main gas is Ar, the auxiliary gas is H2, and the carrier gas is Ar.

[0029] During the spraying process: the current is 500-600A, the main air flow rate is 30-40NLPM, the powder feeding speed is 3-5r / min, and the spraying distance is 90-110mm.

[0030] The prepared coating powder has a particle size D50≤2um and a high-entropy ceramic phase content >99%.

[0031] Optionally, in some embodiments, the horizontal ball mill is a conventional grinding equipment, consisting of a horizontally placed rotating cylinder and grinding balls inside the cylinder, such as steel balls or ceramic balls. Its working principle is as follows: when the cylinder rotates, the grinding balls are lifted to a certain height by centrifugal force and then fall freely, crushing the material through impact and grinding. In this embodiment, the horizontal ball mill undertakes two core tasks: mechanical alloying and slurry preparation. In S120, it promotes the uniform mixing of five rare earth oxide powders at the atomic level through high-energy mechanical force, which is an important prerequisite for forming a uniform high-entropy single-phase structure. In S140, it is again used to crush the mixed powder together with deionized water and binder to form a stable and well-dispersed slurry, preparing for fine grinding and spraying. The forced-air drying oven uses a built-in fan to force the hot air inside the oven to circulate, achieving rapid and uniform heating and drying effects. Its core features are uniform temperature field and precise temperature control; the forced-air drying oven is mainly used to remove moisture to ensure powder quality; in S120, it is used to dry the mixed powder after ball milling, removing introduced moisture and preventing cracking or component segregation due to moisture evaporation during subsequent high-temperature sintering; in S160, it performs secondary drying on the powder for spraying, ensuring that the powder has good flowability and dispersibility to meet the stringent requirements of plasma physical vapor deposition for powder feeding. The high-temperature box-type muffle furnace is a closed high-temperature heat treatment device. Its furnace chamber isolates the sample from the heating element, providing a precise and controllable high-temperature environment; it is the core equipment for heat treatment such as calcination, sintering, and solid-state reaction of materials; the muffle furnace is used to perform key high-temperature sintering solid-state synthesis; it provides a stable and uniform high-temperature environment for the solid-state reaction of five rare earth oxides, transforming mechanically mixed multiple oxide powders into high-entropy ceramic phases with a single rock salt or fluorite structure through atomic diffusion and chemical reconstruction; it is a decisive step in obtaining the target high-entropy oxide phase. Solid-phase synthesis is a traditional method for preparing ceramic materials, referring to the mixing and reaction of solid raw material powders at high temperatures, forming new compounds or solid solutions through interatomic diffusion and migration. Solid-phase synthesis specifically refers to reactions occurring in high-temperature box-type muffle furnaces. Its key lies in utilizing the thermodynamic driving force of the high-entropy effect to promote the interdiffusion of five equimolar ratio rare earth oxides at high temperatures, forming a single, stable high-entropy ceramic phase. This high-entropy single-phase structure is the foundation for coatings to achieve excellent properties, such as low thermal conductivity and high phase stability. Binders are substances added during the preparation of spray slurries or powders. Their main function is to temporarily bind solid particles together to improve the rheological properties, suspension, and formability of the slurry. The binder is added to a horizontal ball mill along with the mixed powder and deionized water in S140. Its role is to form a slurry with good flowability and stability, ensuring that the powder particles remain uniformly distributed during subsequent vertical milling and drying processes, ultimately obtaining a fine-grained, highly flowable spray powder.Spray coating powder refers to powder materials that, after a series of pretreatments such as mixing, synthesis, crushing, classification, and drying, meet the requirements of specific thermal spraying processes and are used for final spray coating deposition. The powder processed through all steps S110 to S160 is the spray coating powder, and its quality directly determines the structure and performance of the final coating. Through strict process control, this powder possesses the precise chemical composition, single high-entropy phase, suitable particle size distribution, and good flowability required by the PS-PVD process, making it a key link between powder preparation and coating deposition. Plasma physical vapor deposition is a relatively new thermal barrier coating preparation technology that combines the characteristics of plasma spraying (APS) and physical vapor deposition (PVD). Its core is to use a high-energy plasma beam in a low-pressure environment to instantly heat the injected powder material to a vaporized state, and then the gaseous particles epitaxially grow on the substrate surface to form a coating. PS-PVD is a key technology for final film formation. Its low-pressure, high-energy environment allows for the full vaporization of high-entropy oxide powder. During deposition, gaseous particles grow epitaxially on the substrate surface, forming a dense columnar crystalline structure. The unique microstructure, through a multiple light scattering mechanism, endows the coating with an average reflectivity exceeding 75% in the infrared to visible spectral range, which is crucial for achieving excellent laser thermal protection performance. Compared to traditional methods, PS-PVD-prepared coatings exhibit lower thermal conductivity and better thermal shock resistance.

[0032] In this embodiment of the invention, the high-reflectivity laser thermal protective coating achieves functional optimization through the following mechanisms: Raw material ratio control ensures that the five rare earth oxides form a high-entropy single-phase structure in an equimolar ratio; the multi-component solid solution significantly improves the phase stability and thermodynamic stability of the coating through lattice distortion effects, providing a homogeneous precursor. Horizontal ball milling achieves mechanical alloying of the powder, promoting atomic-level mixing of each component; combined with forced-air drying to remove moisture, it avoids component segregation during subsequent high-temperature sintering; solid-phase synthesis in a high-temperature box-type muffle furnace forms a single rock salt or fluorite structure high-entropy ceramic phase through diffusion-dominated reactions; furnace cooling controls grain size to reduce internal stress. Secondary ball milling, combined with deionized water and binder, forms a stable slurry; vertical sand milling further reduces particle size to submicron levels, enhancing particle fluidization characteristics during spraying; secondary drying in a forced-air oven ensures powder flowability and adaptability to plasma spraying. The low-pressure environment and high-energy plasma beam of plasma physical vapor deposition technology enable the powder to be fully vaporized. During the deposition process, gaseous particles grow epitaxially on the substrate surface to form a dense columnar crystal structure. The microstructure enables the coating to achieve an average reflectance of more than 75% in the infrared to visible spectrum range through multiple light scattering mechanisms.

[0033] In summary, this embodiment, through component design, microstructure regulation, and deposition kinetics optimization, ultimately obtains a rare-earth high-entropy oxide protective coating with high thermal conductivity, low thermal expansion coefficient, and high laser reflectivity.

[0034] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0035] The above is an introduction to the method embodiments. The following specific embodiments will further illustrate the solution of the present invention.

[0036] Optionally, in some embodiments, this embodiment provides a heat-protective coating, the preparation method of which includes: Step 1: Weigh the raw material powder according to the mass ratio.

[0037] Step 2: Put the proportioned powder into a horizontal ball mill and stir. After mixing evenly, place it in a forced-air drying oven for drying.

[0038] Step 3: Place the dried powder in a high-temperature box-type muffle furnace for high-temperature sintering solid-phase synthesis. The sintering temperature is 1500℃ and the sintering time is 3-5h to form a single-phase defect fluorite (disordered) structure with a grain size of 100-200nm. The five rare earth elements are uniformly distributed. Then, the furnace is cooled to room temperature.

[0039] Step 4: Place the mixed powder, deionized water, and binder into a horizontal ball mill for crushing.

[0040] Step 5: Put the crushed material into a vertical sand mill for further crushing and refining to obtain a mixed powder.

[0041] Step 6: Dry the spray powder using a forced-air drying oven, and then load the dried spray powder into the powder feeder.

[0042] Step 7: Apply the material to the surface of the substrate sample using plasma physical vapor deposition (PS-PVD) to complete the preparation of the thermal protective coating. During the PS-PVD spraying process, the main gas is Ar, the auxiliary gas is H2, and the carrier gas is Ar. The current is 500–600 A, the main gas flow rate is 30–40 NLPM, the powder feed rate is 3–5 r / min, and the spraying distance is 90–110 mm.

[0043] The final coated powder has a particle size D50 ≤ 2 μm and a high-entropy ceramic phase content > 99%.

[0044] like Figures 3-7 As shown, the coated sample was subjected to 1000 cycles of 1200℃ flame thermal shock, and the coating did not peel off or crack.

[0045] Optionally, in some embodiments, this embodiment provides a heat-protective coating, the preparation method of which is the same as that of Embodiment 1 above, and the specific process parameters are as follows: Step 1: Weigh the raw material powder according to the mass ratio.

[0046] Step 2: Put the proportioned powder into a horizontal ball mill and stir. After mixing evenly, place it in a forced-air drying oven for drying.

[0047] Step 3: Place the dried powder in a high-temperature box-type muffle furnace for high-temperature sintering solid-phase synthesis. The sintering temperature is 1500℃ and the sintering time is 3-5h to form a single-phase defect fluorite (disordered) structure with a grain size of 100-200nm. The five rare earth elements are uniformly distributed. Then, the furnace is cooled to room temperature.

[0048] Step 4: Place the mixed powder, deionized water, and binder into a horizontal ball mill for crushing.

[0049] Step 5: Put the crushed material into a vertical sand mill for further crushing and refining to obtain a mixed powder.

[0050] Step 6: Dry the spray powder using a forced-air drying oven, and then load the dried spray powder into the powder feeder.

[0051] Step 7: Apply the material to the surface of the alloy substrate sample using plasma physical vapor deposition (PS-PVD) to complete the preparation of the thermal protective coating. During the PS-PVD spraying process, the main gas is Ar, the auxiliary gas is H2, and the carrier gas is Ar. The current is 500–600 A, the main gas flow rate is 30–40 NLPM, the powder feed rate is 3–5 r / min, and the spraying distance is 90–110 mm.

[0052] The final coated powder has a particle size D50 ≤ 2 μm and a high-entropy ceramic phase content > 99%.

[0053] like Figures 5-7 As shown, a high-energy laser was used to conduct an impact test on the coated sample. The laser spot size was 12 mm and the laser power density was 500 W / cm². 2 The irradiation time was 180 seconds, and the coating did not peel off or crack after laser irradiation.

[0054] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the described module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0055] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0056] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A laser-thermal protective high-entropy oxide coating, characterized in that, It is a high-entropy rare earth oxide ceramic powder material with a multi-component disordered single-phase structure, and the average surface reflectivity of the coating is higher than 75%.

2. The laser thermal protection high-entropy oxide coating according to claim 1, characterized in that, High-entropy rare earth oxide ceramic powder materials in equal mass ratios include yttrium, gadolinium, erbium, ytterbium, and lutetium.

3. The laser thermal protection high-entropy oxide coating according to claim 2, characterized in that, in, Yttrium, gadolinium, erbium, ytterbium, and lutetium each account for 20% of the total mass.

4. The method for preparing a laser thermal protection high-entropy oxide coating according to claim 1, characterized in that, The prepared coating powder has a particle size D50≤2um and a high-entropy ceramic phase content >99%.

5. A method for preparing a laser-thermal protective high-entropy oxide coating, characterized in that, The preparation of the laser thermal protection high-entropy oxide coating according to any one of claims 1-4 comprises: Weigh the raw material powder according to the mass ratio; The proportioned powder is placed in a horizontal ball mill and stirred until evenly mixed. Then it is placed in a forced-air drying oven for drying. The dried powder was placed in a high-temperature box-type muffle furnace for high-temperature sintering solid-phase synthesis, and then cooled to room temperature with the furnace. The mixed powder, deionized water, and binder are placed into a horizontal ball mill for crushing; The crushed material is put into a vertical sand mill for further crushing and refining to obtain a mixed powder; Dry the spray powder using a forced-air drying oven, and then load the dried spray powder into the powder feeder; The thermal protective coating was prepared by spraying the material onto the surface of the substrate sample using plasma physical vapor deposition.

6. The method for preparing a laser thermal protection high-entropy oxide coating according to claim 5, characterized in that, The sintering temperature of the high-temperature box-type muffle furnace is 1500℃, forming a single-phase defect fluorite structure, and the five rare earth elements are evenly distributed.

7. The method for preparing a laser thermal protection high-entropy oxide coating according to claim 6, characterized in that, High-temperature box-type muffle furnaces are used to perform high-temperature sintering solid-phase synthesis; they provide a high-temperature environment for the solid-phase reaction of five high-entropy rare earth oxides, and transform mechanically mixed high-entropy rare earth oxide powders into high-entropy ceramic phases through atomic diffusion and chemical reconstruction.

8. The method for preparing a laser thermal protection high-entropy oxide coating according to claim 5, characterized in that, The mass of the binder is 3% to 5% of the mass of the mixed powder.

9. The method for preparing a laser thermal protection high-entropy oxide coating according to claim 5, characterized in that, In the plasma physical vapor deposition spraying process, the main gas is Ar, the auxiliary gas is H2, and the carrier gas is Ar.

10. The method for preparing a laser thermal protection high-entropy oxide coating according to claim 9, characterized in that, During the spraying process: the current is 500-600A, the main air flow rate is 30-40NLPM, the powder feeding speed is 3-5r / min, and the spraying distance is 90-110mm.

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