Modified high-temperature-resistant ceramic-based antioxidant composite coating material and preparation method thereof

Abstract

The invention relates to the technical field of thermal spraying powder materials, and discloses a modified high-temperature-resistant ceramic-based antioxidant composite coating material and a preparation method thereof.The modified high-temperature-resistant ceramic-based antioxidant composite coating material comprises composite powder, and particles of the composite powder are formed by coating a latent reducing agent core with a ceramic shell layer; during spraying, the shell layer is molten to trigger the inner core to perform in-situ reduction, in-situ oxidation is repaired, and the coating is self-reinforced by utilizing a byproduct; according to the method, through an internal chemical self-healing mechanism, the anti-oxidation function is converted from a spraying process depending on external high energy consumption and high stress into a process of autonomously completing the material at the melting moment, and the anti-oxidation function is achieved at the melting moment. The contradiction between the cost efficiency and the coating quality in the traditional process is solved, and a chemically-bonded tough interface is constructed while the chemical purity of the coating is realized.

Description

Technical Field

[0001] This invention relates to a modified high-temperature resistant ceramic-based antioxidant composite coating material and its preparation method, belonging to the technical field of thermal spray powder materials. Background Technology

[0002] Currently, plasma spraying is a commonly used technology for obtaining dense, high-performance protective coatings. Its principle is to heat ceramic powder to a molten or semi-molten state in a high-temperature jet and then deposit it into a film by impacting the substrate surface at high speed. The final performance of the coating largely depends on the maintenance of the chemical purity of the coating material during the deposition process.

[0003] However, this technological approach has a fundamental inherent constraint: the high-temperature conditions required for powder melting directly conflict with the goal of maintaining the chemical purity of the material, most notably in the oxidation during powder flight. To alleviate this problem, the industry commonly adopts a high-energy, high-speed process strategy, which involves increasing the power and velocity of the plasma jet to shorten the residence time of powder particles in the high-temperature zone, as a conventional solution to suppress in-transit oxidation. While this approach controls oxidation to some extent, the manufacturing process itself generates several systemic negative effects. Specifically, its inherent limitations are: 1. High operating power and high consumption of valuable plasma gas directly increase manufacturing costs; 2. Excessively high particle flight velocity causes some molten particles to bounce off the substrate surface, resulting in reduced deposition efficiency and material loss; 3. The excessive kinetic energy of the molten droplets impacting the substrate and rapid cooling accumulate residual stress within the coating, adversely affecting the long-term reliability of the coating.

[0004] To address the aforementioned constraints, engineers have attempted improvements by optimizing the external protective atmosphere or physically blending conventional reducing agents into the powder. However, these linear improvement approaches have failed to fundamentally solve the problem. The former suffers from difficulty in completely isolating oxygen due to the inherent entrainment effect of the jet and is also costly, while the latter has limited effectiveness due to the premature failure of the reducing agent at high temperatures or poor compatibility with functional ceramics. Analysis shows that both approaches treat in-transit oxidation as an issue that needs to be countered or avoided through external process parameters. This external countermeasure approach creates an irreconcilable negative correlation between process cost, deposition efficiency, and coating quality. Therefore, the technical problem to be solved by this invention is how to construct an intrinsic mechanism that proactively addresses in-transit oxidation by designing the powder material itself, thereby enabling thermal spraying processes to avoid relying on high-energy-consuming, high-cost, and high-stress process parameters to ensure coating quality. Summary of the Invention

[0005] This invention provides a modified high-temperature resistant ceramic-based antioxidant composite coating material and its preparation method. Its main purpose is to solve the problem that existing thermal spray powders rely excessively on external high-energy-consuming and high-stress process parameters when suppressing oxidation in transit, thus causing an inherent contradiction between cost efficiency and coating quality.

[0006] To achieve the above objectives, the present invention provides a modified high-temperature resistant ceramic-based antioxidant composite coating material, which is a composite powder. The particles of the composite powder have the following chemical composition and structural limitations: A ceramic shell primarily composed of yttrium-stabilized zirconium oxide; The reducing core is composed of rare earth metal borides and is completely covered by a ceramic shell. The chemical reaction of the reducing core is configured to be triggered only after the ceramic shell reaches the melting temperature and forms a liquid phase in the thermal spray jet. It undergoes an in-situ reduction reaction with the molten ceramic shell to repair the oxygen deficiency formed by oxidation in transit. The rare earth oxides, a byproduct of the in-situ reduction reaction, are dissolved in the zirconium oxide lattice as a stabilizer, while the byproduct boron segregates at the grain boundaries after solidification. Furthermore, the content of rare earth metal borides in the reducing core is excessive relative to the stoichiometry required to completely repair the oxidation in transit. This allows the residual active boron after the in-situ reduction reaction to react in-situ at the interface when the particles are deposited on the metal substrate, generating a continuous metal boride metallurgical bonding layer that serves as the chemical bonding interface between the coating and the substrate.

[0007] Preferably, the rare earth metal borides are lanthanum hexaboride or cerium hexaboride; the metallurgical bonding layer of the metal borides is a nickel-based metal boride or a cobalt-based metal boride, and the thickness of the bonding layer between the coating and the metal substrate is 50 nanometers to 200 nanometers.

[0008] Preferably, the reducing core further includes an aluminothermic component composed of nano-aluminum powder and nano-metal oxides; the aluminothermic component is configured to be triggered synchronously with the chemical reaction of the reducing core, providing an endogenous heat source for the molten droplets through an instantaneous exothermic reaction to prolong their solidification time, thereby providing a sufficient reaction time window for the in-situ reduction reaction and the formation of the metallurgical bonding layer of metal boride.

[0009] Preferably, the ceramic shell is a multi-layer structure comprising: an inner shell layer composed of yttrium-stabilized zirconium oxide that is in direct contact with the reducing core; and an outer sacrificial layer composed of molybdenum disilicide or silicon carbide that covers the inner shell layer; the outer sacrificial layer is configured to preferentially oxidize to form a dense silica glassy film when entering the thermal spray jet, in order to undertake the first stage of anti-oxidation function.

[0010] Preferably, the reducing core contains at least two reducing agents with different reduction potentials, including: a first reducing agent with a lower reduction potential, which is zirconium hydride or silicon nitride; and a second reducing agent with a higher reduction potential, which is a rare earth metal boride; the first reducing agent is configured to preferentially undergo a reduction reaction under mild oxidation conditions, and the second reducing agent initiates a reduction reaction under severe oxidation conditions after the first reducing agent is consumed.

[0011] Preferably, the ceramic shell is further doped with a second rare earth oxide as a spectral tracer; the reference characteristic spectral intensity emitted by the spectral tracer is The characteristic spectral intensity of the rare earth oxide emission byproduct of the in-situ reduction reaction is: The ratio of the two is used to calculate a dimensionless index characterizing the healing strength of a unit of powder. The calculation rules are as follows: in, and To obtain the integrated intensity of the characteristic spectral lines of the corresponding elements in real time during the thermal spraying process using a spectrometer, the ceramic shell further contains a colorimetric indicator sensitive to redox atmosphere, namely cobalt oxide or manganese oxide. The colorimetric indicator is configured such that when the in-situ reduction reaction occurs successfully, it is reduced to a metallic state in the reducing atmosphere inside the molten droplet, making the final deposition point appear white; while when the in-situ reduction reaction fails, it reacts with zirconium oxide in an oxidizing atmosphere to form a blue cobalt-zirconium spinel or a brown manganese-zirconium solid solution, thereby optically marking the failed deposition point.

[0012] Preferably, based on 100 parts by weight of the total composite powder, it comprises: 85 to 95 parts by weight of a ceramic shell; and 5 to 15 parts by weight of a reducing core.

[0013] Preferably, the boron segregated at the grain boundaries exists in the form of an amorphous or nanocrystalline boride phase, which is used to pin the grain boundaries and suppress the growth of zirconia grains at high temperatures.

[0014] Preferably, the metal boride metallurgical bonding layer is a gradient layer, the composition of which gradually changes from the boron-rich metal phase near the metal matrix to the metal boride phase near the ceramic shell, thereby achieving a smooth transition from metal to ceramic in terms of thermal expansion coefficient and elastic modulus.

[0015] A method for preparing a modified high-temperature resistant ceramic-based antioxidant composite coating material, the method comprising the following steps: Step 1: Provide a modified high-temperature resistant ceramic-based antioxidant composite coating material as a spraying raw material; Step 2: Using plasma spraying, the raw material is heated to a molten state and deposited onto the metal substrate. The operating power and gas flow rate of the plasma spraying process are set within a process window that is lower than the parameters required to suppress the oxidation of conventional yttrium-stabilized zirconia powder in transit. The energy input of this process window only needs to meet the condition of completely melting the ceramic shell of the raw material.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. A reducing agent that is activated only at melting temperature is placed in the core, and coated with a high-temperature resistant ceramic material as the shell. During the thermal spraying process, when the powder particles are heated to a molten state, the shell material mixes with the core reducing agent. The latter immediately undergoes an in-situ reduction reaction with the shell oxides formed during flight. This inherent spontaneous chemical repair process transforms the control of powder oxidation during flight from relying on external high-energy and high-speed spraying processes to being completed autonomously by the powder material itself at the moment of melting. This allows the thermal spraying process to be carried out under milder energy and speed conditions to obtain a coating with lower residual stress and higher deposition efficiency.

[0017] 2. By setting the content of rare earth metal borides in the core within a specific range that exceeds the stoichiometry required for complete reduction of the shell oxide, after the powder droplet completes its primary internal self-healing reaction, the remaining highly active boron elements will preferentially accumulate at the interface between the coating and the substrate when the droplet impacts the substrate. These boron elements can remove transient oxides on the surface of the metal substrate on the one hand, and react with the cleaned metal substrate surface on the other hand to generate a dense metal boride transition layer in situ. This transition layer establishes a continuous chemical bond between the ceramic coating and the metal substrate, transforming the traditional physical interlocking interface into a chemical metallurgical bonding interface.

[0018] 3. In addition to the high-temperature resistant ceramic shell, a non-oxide ceramic sacrificial layer that is more easily oxidized than the ceramic material is further coated, thus forming a double-shell structure. When the powder particles carrying this structure enter the high-temperature jet, the outermost sacrificial shell takes effect first, forming a dense glassy film through self-oxidation. This film undertakes the first-stage protection of blocking most of the external oxygen. This protects the inner high-temperature resistant ceramic main shell and functional core from the direct impact of extreme oxidation environment, and uses the in-situ reduction self-healing mechanism of the internal core as the second-stage repair method to deal with residual oxidation that has penetrated the first-stage protection. Thus, a single powder particle has the ability to respond in stages to both conventional and extreme oxidation environments.

[0019] 4. A colorimetric indicator sensitive to redox atmosphere is doped into the high-temperature resistant ceramic shell. The chemical valence state and color of this indicator are directly related to the chemical atmosphere inside the droplet. When the latent reducing agent in the core is successfully activated and completes the in-situ reduction reaction, the inside of the droplet is in a strong reducing atmosphere, and the indicator is simultaneously reduced to present the first color. Conversely, if the reduction reaction fails for some reason, the inside of the droplet maintains a strong oxidizing atmosphere, and the indicator reacts with the matrix at high temperature to form a second stable phase with a significant color contrast. This mechanism enables the manufacturing quality of each micron-level deposition point in the coating to be irreversibly self-marked by its final color, realizing direct visualization of internal chemical defects. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the composite powder design and intrinsic chemical self-healing mechanism of the present invention. Figure 2 This diagram illustrates the effect of the self-healing mechanism of this invention on improving the key performance of the coating. Figure 3 This is a schematic diagram of the in-situ reaction of the composite powder and the formation of the coating microstructure of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that the specific embodiments described below are explanations of the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0022] This invention discloses a modified high-temperature resistant ceramic-based antioxidant composite coating material and its preparation method. The material is a composite powder with a specific core-shell structure. Through the material's inherent chemical mechanism, it achieves in-situ repair of oxidation during thermal spraying and self-enhancing of coating performance, while constructing a chemical-metallurgical interface. The particle structure of this composite powder material includes a shell composed of a ceramic matrix and a core composed of a latent reducing agent completely encapsulated by the shell. The coating preparation method utilizes the chemical properties of the composite powder to complete plasma spraying deposition within a low-energy-consumption process window. This invention addresses a key technical challenge in the preparation of thermal barrier coatings for components such as aero-engine turbine blades. The challenge lies in suppressing the oxidation and decomposition of yttrium-stabilized zirconia powder, the main component of the coating, during its journey to the substrate under the high-temperature environment of a plasma jet. To address this challenge, the present invention provides a composite powder material with particles configured in a core-shell structure. The ceramic shell, primarily composed of yttrium-stabilized zirconia, provides the final thermal insulation and structural functions of the coating. The core, completely encapsulated by this ceramic shell, is composed of one or more latent reducing agents. "Latent" means that the reducing agent remains chemically inert during powder storage, transport, and the initial heating phase of the plasma jet; its chemical reaction only occurs when the ceramic shell of the entire powder particle reaches its melting temperature (approximately 2700 °C for yttrium-stabilized zirconia). The reduction is triggered only after the liquid phase is formed; the reducing core can be a rare earth metal boride, such as lanthanum hexaboride (…). ) or cerium hexaboride ( When the yttrium-stabilized zirconium oxide shell melts into droplets, the core... When mixed with and activated by high temperature, oxygen deficiencies are formed in the molten droplets due to oxidation during the process, which are chemically represented as follows: Non-stoichiometric oxides of lanthanum will undergo an in-situ reduction reaction with lanthanum, the reaction diagram of which is as follows: This restores zirconium oxide that deviates from its stoichiometric ratio to pure zirconium oxide. This chemical self-healing mechanism means that the inhibition of oxidation during the process no longer depends on external high-energy and high-speed spraying processes, but is completed autonomously by the material itself at the moment of melting.

[0023] In the above-mentioned in-situ reduction reaction, the byproducts are also designed as reinforcing components beneficial to coating performance; among them, rare earth oxides, such as lanthanum oxide (… As a zirconia stabilizer, it can dissolve in the zirconia lattice after the reaction, improving the phase stability of the coating under long-term high-temperature service. Boron, a byproduct, has a small atomic radius and limited solubility in oxide melts. During the rapid solidification of the coating droplets, it segregates and eventually accumulates at the grain boundaries of the solidified zirconia grains. This segregated boron can exist as amorphous or nanocrystalline boride phases, pinning the grain boundaries and inhibiting the coarsening and growth of zirconia grains at high temperatures, thereby improving the coating's toughness. To achieve the above functions, the composite powder... The composition of the composite powder is defined as follows: based on a total weight of 100 parts, it contains 85 to 95 parts by weight of a ceramic shell and 5 to 15 parts by weight of a reducing core. The determination of this ratio range is based on the fact that when the content of the reducing core is less than 5 parts by weight, the total amount of reducing agent is insufficient to completely repair the oxidation in transit under typical plasma spraying conditions; while when its content is greater than 15 parts by weight, excessive byproducts may form a continuous network at the grain boundaries, which will have an adverse effect on the mechanical properties of the coating. Therefore, this range is a range that balances the self-healing ability and the final mechanical properties of the coating.

[0024] Regarding the bonding strength between the coating and the metal substrate, the conventional physical interlocking interface is a weak point in coating failure. This invention achieves in-situ chemical metallurgical bonding at the interface by configuring the reducing agent content in the reducing core. The content of rare earth metal borides in the core is set to be excessive relative to the stoichiometry required for complete repair of ongoing oxidation. This ensures that after the powder droplets complete their internal self-healing reaction, the residual active boron elements preferentially accumulate at the coating-substrate interface when the droplets impact and spread onto the metal substrate surface. These highly active boron elements can remove transient oxygen from the metal substrate surface (such as nickel-based or cobalt-based superalloys). On the one hand, the boron compound reacts in situ with the cleaned metal substrate surface to generate a continuous metal boride metallurgical bonding layer with a thickness between 50 and 200 nanometers. The phase of this layer is either nickel-based or cobalt-based metal boride. This metallurgical bonding layer connects the ceramic coating to the metal substrate through chemical bonds. Furthermore, this metal boride metallurgical bonding layer can be constructed as a gradient layer, with its composition gradually changing from a boron-rich metal phase near the metal substrate side to a metal boride-rich phase near the ceramic coating side. This achieves a transition from metal to ceramic in terms of thermal expansion coefficient and elastic modulus, alleviating stress concentration at the interface.

[0025] To cope with the more severe or dynamically changing oxidation environment during thermal spraying, the structure of the composite powder can be further configured; in one embodiment, to address the problem of shortened reaction time due to excessively rapid droplet cooling when sprayed onto thin-walled structures or high thermal conductivity substrates, the reducing core may further include nano-aluminum powder and nano-metal oxides (such as... The thermite component is configured to trigger the chemical reaction of the reduction core simultaneously, providing a supplementary heat source for the molten droplets about to solidify through an instantaneous exothermic reaction, thereby extending the duration of its molten state and providing more sufficient reaction time for the in-situ reduction reaction and the formation of the metallurgical bonding layer of the metal boride. In another embodiment, to cope with the oxidation shock that may occur during the non-steady-state stages such as the start and stop of the spray gun, the ceramic shell can be designed as a multi-layer structure, which includes an inner shell layer made of yttrium-stabilized zirconium oxide in direct contact with the reduction core, and a layer of molybdenum disilicide (…) covering the inner shell layer. ) or silicon carbide ( The outer shell sacrificial layer is composed of ); when powder particles carrying this structure enter the thermal spray jet, the more easily oxidized outer shell sacrificial layer will preferentially oxidize itself to form a dense layer of silicon dioxide () A glassy thin film serves as the first-stage oxygen barrier, employing an internal in-situ reduction and self-healing mechanism as a second-stage repair method to address residual oxidation that has penetrated the first-stage protection. This enables a single powder particle to possess a graded response capability to oxidation environments of varying intensities. In another embodiment, to achieve adaptive repair to oxidation environments of different degrees, the reduction core may contain at least two reducing agents with different reduction potentials. For example, a first reducing agent with a lower reduction potential (such as zirconium hydride) or silicon nitride ), and a second reducing agent with a high reduction potential (rare earth metal borides) This configuration allows the more chemically reactive first reducing agent to preferentially undergo reduction under mild oxidation conditions, while the second reducing agent only initiates reduction under severe oxidation conditions after the first reducing agent has been consumed.

[0026] To achieve online diagnosis and quality control of the thermal spraying process, the composite powder material of this invention can also integrate information tracing functionality; one technical solution is to further dope the ceramic shell with a second rare earth oxide (such as...) as a spectral tracer. Its reference characteristic spectral intensity emitted in plasma is The in-situ reduction reaction byproducts are rare earth oxides (such as...) The emission response characteristic spectral intensity is By acquiring the integrated intensity of the characteristic spectral lines of these two corresponding elements in real time using a spectrometer and calculating their ratio, a dimensionless index characterizing the healing strength of a unit powder can be obtained. The calculation rules are as follows: In the formula, The reference characteristic spectral intensity of the emission of the spectral tracer. The index represents the characteristic spectral intensity emitted by rare earth oxides, a byproduct of the in-situ reduction reaction. This index eliminates the influence of system noise such as plasma temperature fluctuations and powder feeding rate jitter through an internal reference, transforming the chemical repair process into a quantifiable digital indicator that can be read in real time. Another technical solution involves further including a colorimetric indicator sensitive to redox atmosphere, such as cobalt oxide, in the ceramic shell. ) or manganese oxide ( The colorimetric indicator is configured such that, when the in-situ reduction reaction occurs successfully, it is reduced to a metallic state (such as metallic cobalt) in the reducing atmosphere inside the molten droplet, making the final deposition point appear white as the ceramic matrix itself; while when the in-situ reduction reaction fails, it reacts with the zirconium oxide matrix in the oxidizing atmosphere inside the molten droplet to form a blue cobalt-zirconium spinel or a brown manganese-zirconium solid solution, thereby optically marking the failed deposition point; the present invention also provides a method for preparing a coating using any of the modified high-temperature resistant ceramic matrix antioxidant composite coating materials, the method comprising the following steps: first, providing a composite powder material as a spraying raw material; then, using a plasma spraying process, heating the spraying raw material to a molten state and High-speed deposition onto a metal substrate; due to the inherent antioxidant and self-healing capabilities of the coating material itself, the operating parameters of this plasma spraying process, especially the operating power and plasma gas flow rate, can be set within a process window lower than the parameters required to suppress the in-transit oxidation of conventional yttrium-stabilized zirconia powder; the energy input within this process window only needs to meet the condition of completely melting the ceramic shell of the coating material, without needing to shorten the residence time of the powder in the high-temperature zone through high-energy and high-speed methods; this spraying process reduces energy consumption and gas costs, and improves deposition efficiency due to the lower particle flight velocity. At the same time, the reduced kinetic energy of the molten droplets impacting the substrate results in a relatively gentle cooling rate, reducing the residual stress inside the final coating.

[0027] Example 1: This example illustrates the application of a technical solution in a specific industrial scenario. In the repair of a heavy-duty gas turbine blade, the application involves a nickel-based superalloy blade requiring a new thermal barrier coating due to long-term service, particularly its complex geometry and a trailing edge region with a thickness of only 0.5 mm. The technical challenge in this scenario lies in the quenching effect of the sprayed droplets on the thin-walled trailing edge structure. Furthermore, the high-power plasma spraying used to suppress the oxidation of conventional yttrium-stabilized zirconia powder causes erosion damage to this thin-walled structure due to its high-speed particle flow. Additionally, the excessively high cooling rate accumulates residual stress within the coating, making the physical interface between the coating and the substrate more fragile. To address this situation, a composite material as described in the specific embodiment is selected. The composite powder consists of a yttrium-stabilized zirconia ceramic shell and a multi-component core containing lanthanum hexaboride and nano-aluminothermic agents. The lanthanum hexaboride content is excessive relative to the stoichiometry required for repairing in-transit oxidation. Plasma spraying is used for the coating operation, but its operating power and gas flow rate are set at a low energy input window, which is only sufficient to completely melt the ceramic shell of the composite powder. When the composite powder particles enter the plasma jet and fly towards the blade trailing edge substrate, the surface of its yttrium-stabilized zirconia shell comes into contact with oxygen entrained in the environment, resulting in a certain degree of in-transit oxidation. When the molten particles carrying oxides collide with and spread on the cold metal substrate trailing edge surface, the rapid absorption of heat by the substrate triggers a quenching process.

[0028] In the instant before the molten droplet rapidly solidifies, a series of synergistic chemical and physical processes occur within it. First, the melting activates the nano-aluminothermic component in the core, whose instantaneous exothermic reaction provides a supplementary heat source for the droplet, slowing down its solidification rate and creating a time window for subsequent reactions. Then, within this extended time window, lanthanum hexaboride in the core undergoes an in-situ reduction reaction with oxygen-deficient sites formed during oxidation, restoring zirconium oxide to a stoichiometrically correct phase. After completing the internal self-healing reaction, the residual active boron released from the excess lanthanum hexaboride in the core migrates in the liquid phase to the interface between the coating and the substrate. This reduces and removes transient oxides from the metal substrate surface and reacts with the clean nickel-based metal substrate surface, generating a continuous nickel layer in situ. A metal boride metallurgical bonding layer was formed on the blade trailing edge. After the spraying operation, the coating was inspected, and the results showed that the thermal barrier coating was dense and crack-free. Metallographic analysis showed that the zirconium oxide inside the coating was a chemically pure and stable phase. A continuous, defect-free metal boride metallurgical bonding layer with a thickness of about 100 nanometers was formed between the coating and the nickel-based superalloy substrate. The coating bonding strength test showed that its bonding force was higher than that of coatings prepared by conventional processes. At the same time, the geometric dimensions and contour accuracy of the blade trailing edge were maintained, and no erosion damage caused by the spraying process or deformation caused by thermal stress was observed. This process solved the problem of preparing high-quality coatings on thin-walled parts, and also improved the powder deposition efficiency and reduced the manufacturing cost by using a lower energy input process window.

[0029] To counteract the shortened reaction time window caused by rapid quenching when molten droplets impact a low-temperature or high-thermal-conductivity substrate, the reducing core may further contain an aluminothermic component composed of nano-aluminum powder and nano-ferric oxide. This aluminothermic component functions as a one-time endogenous heat source, triggered synchronously with the chemical reaction in the reducing core. Through a solid-state exothermic reaction, it provides additional enthalpy to the molten droplets to compensate for the heat lost during conduction to the substrate, thereby extending the time from initial spreading to complete solidification. The weight percentage of this aluminothermic component in the reducing core is limited to 15% to 40%. When the component content is below 15%, the total heat released by the reaction is insufficient to macroscopically alter the solidification curve of the droplets, and its effect on extending the liquid phase existence time is not significant, resulting in a discontinuous metallurgical bonding layer at the interface under quenching conditions. When the component content is above 40%, excessive instantaneous exothermic reaction can cause the internal temperature of the droplets to exceed 3000°C. This temperature can cause partial vaporization of boron, a reduction product, or macroscopic segregation during solidification, which reduces the effective boron concentration at the interface. This results in an uneven thickness and porosity in the final metal boride layer, leading to a decrease in coating bonding strength. Therefore, a weight ratio of 15% to 40% represents a technical balance between ensuring sufficient reaction time and avoiding thermal damage to the material. To enable the composite powder to adaptively cope with different intensities and types of oxidation environments in the thermal spray jet, the reduction core may contain at least two reducing agents with different reduction potentials, wherein the first reducing agent is zirconium hydride. Its chemical properties are highly reactive, and it can decompose and undergo a reduction reaction even at relatively low oxidizing atmospheres and temperatures; the second reducing agent is lanthanum hexaboride. Its chemical properties are relatively stable, but it requires higher oxidizing atmospheres and temperatures to be activated. In this configuration, zirconium hydride, as a sacrificial reducing agent, preferentially consumes the small amount of oxygen entrained in the environment during the initial or stable stages of the powder particle flight path; while lanthanum hexaboride, as the main functional reducing agent, is protected in the previous stage and only initiates a deep reduction reaction under severely oxidizing conditions caused by drastic fluctuations in process parameters such as the start and stop of the spray gun, or after the zirconium hydride has been completely consumed, while also undertaking the function of interfacial metallurgical bonding; in the above multi-stage reducing agent system, the molar ratio of the first reducing agent (zirconium hydride) to the second reducing agent (lanthanum hexaboride) is limited to 1. Within the range of 2:2 to 2:1, if the molar ratio is lower than 1:2, the content of the first reducing agent, which acts as a sacrificial agent, is insufficient. It is quickly depleted in a normal oxidizing environment and cannot effectively protect the second reducing agent, which acts as the main functional agent. This reduces the repair margin of the coating when facing instantaneous strong oxidizing shocks. If the molar ratio is higher than 2:1, the content of the second reducing agent, which acts as the main functional agent, is relatively insufficient. Although the pre-stage protection is sufficient, the total amount of excess active boron that it can provide decreases in the final interface reaction stage. This is insufficient to form a metal boride layer with optimal thickness and continuity at the interface between the coating and the substrate, affecting the final coating bonding strength.

[0030] Example 2: To quantify the performance of the composite powder material of the present invention in inhibiting in-transit oxidation and enhancing interfacial bonding, and to determine the core component ratio range, the following comparative experiment was conducted; an atmospheric plasma spraying system was used, with an adjustable spray gun power range of 30kW to 50kW and a powder feeder with an accuracy of ±2%. The substrate used was an Inconel 718 nickel-based high-temperature alloy specimen, and its spraying surface was sandblasted with alumina sand particles, with a surface roughness of Ra6.0±0.5μm; five groups of sprayed powders were prepared, of which control group 1 was commercially available conventional yttrium-stabilized zirconia powder; control group 2 was a core-shell structure powder, with a ceramic shell of yttrium-stabilized zirconia and a core of lanthanum hexaboride, but the core content was only sufficient to theoretically completely repair the... The required stoichiometry for oxidation was determined. The sample group of this invention is a composite powder prepared according to a specific embodiment, comprising 90 parts by weight of a yttrium-stabilized zirconia ceramic shell and 10 parts by weight of a lanthanum hexaboride reducing core. The powder structures of control groups 3 and 4 are the same as those of the sample group of this invention, but the contents of their reducing cores are 3 parts by weight and 20 parts by weight, respectively. All five powder groups were deposited on the substrate specimen using the same plasma spraying process parameters. The energy input of this process window was set at a low level (spraying power 35kW, argon flow rate 45L / min, hydrogen flow rate 8L / min, powder feed rate 25g / min, spraying distance 100mm). This setting was intended to simulate a spraying condition that does not cause excessive heat load to the substrate and saves costs.

[0031] The prepared coating samples were subjected to cross-sectional analysis and performance testing. The microstructure, interface morphology and chemical composition of the coating cross-section were characterized by scanning electron microscopy and energy dispersive spectroscopy. The phase composition of the coating was analyzed by X-ray diffraction. The bonding strength of the coating was measured by tensile testing machine according to ASTM C633 standard. Five samples were tested in each group and the average value was calculated. The comparative data of the coating performance of each group are shown in Table 1.

[0032] Based on microscopic analysis, the conventional yttrium-stabilized zirconia coating in control group 1 showed the presence of some non-stoichiometric phases in its XRD pattern, and EDS analysis also confirmed oxygen depletion within the coating, with simple mechanical intercalation at the interface, resulting in the lowest bonding strength. The coating in control group 2 essentially restored oxygen content to stoichiometry, but due to the lack of excess boron, a continuous metal boride layer did not form at the interface, resulting in a lower bonding strength. The coating of the present invention not only maintained a stoichiometric pure phase but also formed a uniformly thick and dense metal boride metallurgical bonding layer at the coating-substrate interface, correspondingly exhibiting higher bonding strength than control groups 1 and 2. Control group 3, due to reduction... The low core content resulted in insufficient in-situ reduction reaction, failing to resolve the oxygen deficiency problem in the coating. Although control group 4 resolved the oxidation problem, its excessively high core content led to an excessively thick and brittle metal boride layer at the interface, resulting in lower bonding strength compared to the sample group of this invention. The experimental results show that the composite powder material provided by this invention, with its internal self-healing and interface self-bonding mechanisms, and the core component core content ranging from 5 to 15 parts by weight, can synergistically maintain the chemical purity of the coating and transform the interface bonding mode from physical interlocking to chemical metallurgical bonding under low energy input spraying conditions, thereby obtaining a coating with higher bonding strength.

[0033] To further verify from the reverse perspective the indispensability of the latent reduced core in the core-shell structure powder of the present invention under a low-energy-consumption process window, the following comparative examples are provided.

[0034] Comparative Example 1: This comparative example aims to verify whether the final coating performance can meet the requirements when spraying is performed using commercially available conventional yttrium-stabilized zirconia powder used in Control Group 1 of Example 2, instead of the core-shell structure powder of the present invention. Except for replacing the spraying powder with conventional yttrium-stabilized zirconia powder without any reduced core, all other test conditions, including substrate material (Inconel 718 nickel-based superalloy specimen), substrate surface treatment (alumina sandblasting, surface roughness Ra 6.0 ± 0.5 μm), plasma spraying system, and spraying process parameters (spraying power 35 kW, argon flow rate 45 L / min, hydrogen flow rate 8 L / min, powder feed rate 25 g / min, spraying distance 100 mm), are strictly consistent with the present invention sample group in Example 2. This combination of process parameters represents a low-energy spraying condition aimed at reducing manufacturing costs and reducing residual stress in the coating.

[0035] The prepared coating samples were subjected to the same testing and characterization as in Example 2. The results showed that due to the low spraying power and gas flow rate, the powder particles had a relatively slow flight speed in the plasma jet, resulting in a prolonged residence time in the high-temperature zone and significant in-transit oxidation. Specific performance data are as follows: X-ray diffraction (XRD) was used to analyze the coating phase, and obvious diffraction peaks of non-stoichiometric oxides were observed in the spectrum. Quantitative analysis of the micro-area chemical composition of the coating cross-section was performed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), confirming that the average oxygen content inside the coating was approximately 8.2% lower than the theoretical stoichiometric value. Metallographic images of the cross-section showed that the interface between the coating and the substrate was a typical mechanical interlocking, and no continuous metallurgical bonding layer generated by chemical reaction was observed. According to ASTM C633 standard, the coating bonding strength of five samples was measured, and the average value was 39.2 MPa, with large data dispersion, indicating poor bonding stability.

[0036] The comparative experimental results show that although the low-energy spraying process has significant advantages in cost control and residual stress reduction, its direct application to conventional yttrium-stabilized zirconia powder cannot avoid the problems of decreased coating chemical purity and phase degradation caused by in-transit oxidation. The resulting coating, due to numerous oxidation defects and purely physical bonding at the interface, cannot even consistently achieve the bonding strength required by conventional high-energy processes. This result conversely demonstrates that the "in-situ reduction self-healing" mechanism proposed in this invention, which involves constructing a "in-situ reduction self-healing" mechanism within the powder material, is key to achieving the preparation of high-quality, high-bonding-strength ceramic coatings within a low-energy, low-cost process window.

[0037] Example 3: This example combines Figures 1 to 3 This document describes a modified high-temperature resistant ceramic-based antioxidant composite coating material and its preparation method, such as... Figure 1 As shown, the process is divided into three stages. Stage one involves the design and preparation of the composite powder material, the core of which is a core-shell structured composite powder particle. This particle consists of a ceramic shell (A) made of yttrium-stabilized zirconium oxide and a reduced core (B) made of latent rare-earth metal borides. Optional enhancement designs are also available, including a double-shell structure with a sacrificial outer shell layer, or a multi-component core containing a biphasic reducing agent or aluminothermic agent, to achieve adaptive repair and endogenous heat compensation. Stage two involves a low-energy plasma spraying process and internal chemical mechanism. In this stage, the composite powder particle is fed into a plasma jet and heated until the shell melts, thereby activating the core and triggering an in-situ reaction. Subsequently, the molten droplets impact the substrate for deposition. During this process, the healing index is calculated in real time using spectral tracing. Alternatively, optical marking of failed deposition points can be achieved through colorimetric indicators, thereby enabling online diagnosis and quality control of the process. Inside the molten droplet, chemical self-healing occurs simultaneously to repair oxidation in transit, in-situ interface reactions utilize excess reducing agents to react with the matrix, and a byproduct self-reinforcing mechanism is employed, namely, solid solution reinforcement and grain boundary pinning using byproducts. Through these mechanisms, a chemically pure coating free of oxygen-deficient defects is ultimately obtained. This coating possesses a strong and tough interface with gradient transition achieved through chemical metallurgy bonding, thus exhibiting excellent mechanical and thermal stability, ultimately forming a high-performance coating.

[0038] like Figure 2 As shown in the figure, the horizontal axis represents five sample groups: control group 1, control group 2, the present invention sample group, control group 3, and control group 4. The vertical axis is divided into left and right axes. The left axis represents the bonding strength (MPa), and the right axis represents the oxidation degree index and interface quality score. The chart contains three performance indicators. The circular data points connected by solid lines represent the bonding strength, the triangular data points connected by dashed lines represent the oxidation degree index, and the square data points connected by dotted lines represent the interface quality score. The chart data shows that the bonding strength of the present invention sample group reaches approximately 72.3 MPa, and its interface quality score also reaches the highest value. At the same time, its oxidation degree index is maintained at a level close to 1.0. This indicates that its comprehensive performance in the three dimensions of bonding strength, interface quality, and oxidation resistance is significantly better than that of the baseline control group 1, as well as control group 3 with insufficient reducing agent content, control group 2 without excessive reducing agent to form a metallurgical bonding layer, and control group 4 with excessive reducing agent content leading to interface embrittlement.

[0039] like Figure 3 As shown, the composite powder particles on the left are constructed into a multi-layered core-shell structure, with a reduced core composed of lanthanum hexaboride (LHB). ) or cerium hexaboride ( From the outside, the layers are: a ceramic shell layer (yttrium-stabilized zirconium oxide) serving as the main coating, and an outermost sacrificial shell layer (molybdenum disilicide). ) or silicon carbide ( The composite powder particles are deposited onto a metal substrate using a thermal spraying process, forming a multi-layered coating structure as shown on the right. The bottom layer is either nickel-based or cobalt-based. A metal matrix composed of an alloy is on which a layer with a thickness of 50 nanometers to 200 nanometers is formed through an in-situ reaction. The metal boride metallurgical bonding layer is formed by the repaired zirconium oxide (ZrO2) on top of the bonding layer. The ceramic coating is composed of boron that is dispersed at the grain boundaries, which together constitute the total thickness of the coating.

[0040] Example 4: This example discloses an engineering procedure for determining the process window of the composite powder material of the present invention in a specific application, and for calibrating key parameters for online quality monitoring. In the process debugging of a plasma spraying production line, the technical problem is how to quickly and non-destructively determine a process parameter window that minimizes energy consumption and ensures the internal chemical quality of the coating, given the specific thermal spraying equipment and workpiece conditions. The challenge here is that traditional process optimization methods rely on extensive destructive testing of samples prepared under different parameters, which is time-consuming and costly. To solve this problem, a system integrating online diagnostic functions is adopted. The calibration process is as follows: The initial state is defined as follows: The equipment used is an atmospheric plasma spraying system, with a fiber-coupled emission spectrometer installed at the spray gun exit. The spectrometer's field of view is focused on the core region of the plasma jet 80mm from the spray gun exit, enabling real-time acquisition of spectral data in this region and calculation of integrated intensity. Its spectral resolution is 0.1nm. The material used is a composite powder as described in the specific embodiment, with a ceramic shell of yttrium-stabilized zirconium oxide doped with europium oxide as a spectral tracer, and a reducing core of lanthanum hexaboride. This process first requires calibrating a benchmark threshold characterizing the healing quality of the coating. ; The calibration process is as follows: First, a set of process parameters (spraying power 40kW, hydrogen flow rate 10L / min) was selected. Under these parameters, the first batch of coating samples was prepared, and the oxygen content inside the coating was confirmed to maintain the stoichiometry by scanning electron microscopy and energy dispersive spectroscopy. At the same time, the healing index measured by online emission spectrometer was recorded. The stability value was 0.95; subsequently, the process parameters were reduced to a level known to cause oxidation defects (spraying power 28kW, hydrogen flow rate 4L / min), and a second batch of coating samples was prepared. Destructive testing revealed an oxygen deficiency within the coating, at which point the recorded values ​​were... The stable value is 0.60; by conducting such comparative tests at multiple process points and establishing correlations, the stability value was determined. When the value is not lower than 0.85, the microchemical quality of the final coating is acceptable; therefore, Set to 0.85.

[0041] exist Once identified, the optimization procedure within the process window is executed; this procedure involves adjusting key process parameters and monitoring them in real time. The response is achieved; taking spraying power and hydrogen flow rate as an example, keeping other parameters constant, the spraying power is adjusted downwards from 40kW in 1kW increments, running stably for 30 seconds at each power point, and the corresponding data is recorded. Average value; when monitored The value is lower than the first time When the current power value is reached, the downward adjustment is stopped, and the previous step value of the current power value, i.e., 34kW, is determined as the minimum usable power at that hydrogen flow rate. For different hydrogen flow rates, i.e., adjusting downwards in steps of 1L / min from 10L / min, the above power scanning process is repeated. Finally, a graph containing multiple combinations of process parameters that meet the requirements can be plotted. A two-dimensional process window diagram showing the conditions; by executing the above procedures, operators can select the parameter combination with the lowest total energy input within the boundaries from this process window diagram, such as the combination of spraying power of 34kW and hydrogen flow rate of 7L / min, as the standard production process. This ensures coating quality and reduces production costs without destructive testing. In subsequent batch production processes, this can be utilized... This quantitative standard enables real-time quality monitoring of the spraying process.

[0042] Example 5: In the industrial production of composite powder materials, to ensure that each powder particle forms a complete core-shell coating structure, that is, to ensure that the rare earth metal boride, which serves as the reducing core, is completely coated by the ceramic shell, so as to avoid premature failure of the reducing agent in the subsequent thermal spraying process, a preparation method combining chemical co-precipitation and spray drying is adopted. The initial materials of this procedure include: a mixed aqueous solution of zirconium oxychloride and yttrium nitrate with a concentration of 0.5 mol / L, and an ethanol suspension of lanthanum hexaboride particles with an average particle size of 200 nm. During preparation, the ethanol suspension of lanthanum hexaboride is added to the aforementioned mixed aqueous solution, and under vigorous stirring, the pH value of the solution is slowly adjusted to 9.0 by adding ammonia dropwise. This process causes the hydrated zirconium oxide and hydrated yttrium oxide precursors to undergo heterogeneous nucleation and growth on the surface of lanthanum hexaboride particles, thereby forming an initial core-shell structure in the liquid phase with lanthanum hexaboride as the core and the precursor as the shell.

[0043] After the co-precipitation step, the resulting slurry is fed into a spray drying tower for drying and granulation. The inlet temperature of the spray dryer is set to 220°C. The outlet temperature is 110°C. The atomization pressure is 0.2 MPa. This step allows for rapid dehydration and solidification of the precursor shell, forming spherical particles with a certain strength. Finally, the powder obtained after spray drying is calcined in air at a rate of 5 kPa / min. Heating rate to 800 The precursor shell is then kept at this temperature for 2 hours. This step completely transforms the precursor shell into crystalline yttrium-stabilized zirconium oxide. At the same time, the calcination temperature is lower than the activation temperature of the reduced core. By performing the above procedure, the final composite powder material has a core integrity rate of more than 99% when the particles are observed in cross-section by scanning electron microscopy.

[0044] Example 6: On a continuously operating automated plasma spraying production line, to address the risk of momentary deviations in process parameters due to accidental equipment failures, such as minor leaks in the air supply pipeline causing oxygen-containing air to be entrained into the plasma jet in a short time, thereby preventing the formation of oxidation defect zones in the corresponding coating area, it is necessary to verify the impact oxidation resistance of the composite powder material. The test object used in this verification procedure is a composite powder with a two-stage defense mechanism, specifically composed of: an outermost sacrificial shell layer made of molybdenum disilicide, a middle main shell layer made of yttrium-stabilized zirconium oxide, and a core containing zirconium hydride and lanthanum hexaboride with different reduction potentials. During the stable operation of the standard spraying process, an air pulse with a duration of 500 milliseconds and a flow rate of 5 L / min is precisely injected into the plasma jet through a high-speed solenoid valve to simulate transient extreme oxidation conditions. During this period, particles carrying the powder fly through the oxygen-rich area.

[0045] In the oxygen-enriched jet, the outermost molybdenum disilicide sacrificial layer of the powder particles reacts first with oxygen, rapidly generating a flowing silica glassy film. This film consumes most of the instantaneously influxed oxygen, providing a dual shielding effect of initial physical barrier and chemical consumption for the inner layers. Residual oxygen penetrating this shielding layer continues to react with the intermediate yttrium-stabilized zirconia main shell, causing it to undergo a certain degree of in-transit oxidation. When the molten particles impact the matrix, the biphase reducing agent in the core is activated. Among them, zirconium hydride, with a lower reduction potential, reacts preferentially, repairing most of the oxidation damage. Subsequently, lanthanum hexaboride, with a higher reduction potential, performs deep reduction on the remaining, more difficult-to-repair oxides. After the experiment, Raman spectroscopy was used to perform point-by-point scanning analysis on the coating surface, especially high-density scanning in the region corresponding to the air pulse injection time period. The analysis results show that the zirconia on the entire coating surface exhibits characteristic peaks of monoclinic and tetragonal phases with correct stoichiometry, and no metastable phase characteristic peaks caused by oxygen deficits were detected in any region.

[0046] Example 7: This example discloses a procedure for offline rapid screening of coating micro-area quality using a colorimetric indicator integrated in a composite powder material. On a workpiece that has already been coated, to perform non-destructive evaluation of the coating's micro-defects, an optical microscope equipped with a high-resolution charge-coupled device (CCD) camera is used to automatically scan and image the coating surface. The composite powder used has cobalt oxide doped in its ceramic shell as a colorimetric indicator. In the acquired digital images, image processing software is used to analyze the color information, and the results show that over 99.9% of the coating surface area... The coating appears uniformly white, but in some isolated micron-sized areas, the software identifies and marks several discrete points that are blue. To verify the marking points, one of the blue points was randomly selected, and its micro-area composition was analyzed using scanning electron microscopy and energy dispersive spectroscopy. The analysis results confirmed that the point was a cobalt zircon spinel phase, and that the surrounding zirconium oxide matrix was oxygen-deficient. This result confirmed that the in-situ reduction reaction at the deposition point failed to occur. This procedure shows that the color difference generated by the colorimetric indicator can be used to quickly and non-destructively locate and identify micron-sized chemical defects in the coating.

[0047] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A modified high-temperature resistant ceramic-based antioxidant composite coating material, which is a composite powder, wherein the particles of the composite powder have the following chemical composition and structural limitations: A ceramic shell primarily composed of yttrium-stabilized zirconium oxide; The reducing core is composed of rare earth metal borides and is completely covered by a ceramic shell. The chemical reaction of the reducing core is configured to be triggered only after the ceramic shell reaches the melting temperature and forms a liquid phase in the thermal spray jet. It undergoes an in-situ reduction reaction with the molten ceramic shell to repair the oxygen deficiency formed by oxidation in transit. The rare earth oxides, a byproduct of the in-situ reduction reaction, are dissolved in the zirconium oxide lattice as a stabilizer, while the byproduct boron segregates at the grain boundaries after solidification. Furthermore, the content of rare earth metal borides in the reducing core is excessive relative to the stoichiometry required to completely repair the oxidation in transit. This allows the residual active boron after the in-situ reduction reaction to react in-situ at the interface when the particles are deposited on the metal substrate, generating a continuous metal boride metallurgical bonding layer that serves as the chemical bonding interface between the coating and the substrate.

2. The modified high-temperature resistant ceramic-based antioxidant composite coating material according to claim 1, characterized in that, The rare earth metal borides are lanthanum hexaboride or cerium hexaboride; the metallurgical bonding layer of the metal borides is a nickel-based metal boride or a cobalt-based metal boride, and the thickness of the bonding layer between the coating and the metal substrate is 50 nanometers to 200 nanometers.

3. The modified high-temperature resistant ceramic-based antioxidant composite coating material according to claim 1, characterized in that, The reducing core further includes an aluminothermic component composed of nano-aluminum powder and nano-metal oxides; the aluminothermic component is configured to be triggered synchronously with the chemical reaction of the reducing core, providing an endogenous heat source for the molten droplets through an instantaneous exothermic reaction to prolong their solidification time.

4. The modified high-temperature resistant ceramic-based antioxidant composite coating material according to claim 1, characterized in that, The ceramic shell is a multi-layer structure comprising: an inner shell layer composed of yttrium-stabilized zirconium oxide that is in direct contact with the reduced core; and an outer sacrificial layer composed of molybdenum disilicide or silicon carbide that covers the inner shell layer; the outer sacrificial layer is configured to preferentially oxidize to form a dense silica glassy film when entering the thermal spray jet.

5. The modified high-temperature resistant ceramic-based antioxidant composite coating material according to claim 1, characterized in that, The reducing core contains at least two reducing agents with different reduction potentials, including: a first reducing agent with a lower reduction potential, which is zirconium hydride or silicon nitride; and a second reducing agent with a higher reduction potential, which is a rare earth metal boride; the first reducing agent is configured to preferentially undergo a reduction reaction under mild oxidation conditions, and the second reducing agent initiates a reduction reaction under severe oxidation conditions after the first reducing agent is consumed.

6. The modified high-temperature resistant ceramic-based antioxidant composite coating material according to claim 1, characterized in that, The ceramic shell is further doped with a second rare-earth oxide as a spectral tracer; the reference characteristic spectral intensity of the emitted spectral tracer is... The characteristic spectral intensity of the rare earth oxide emission byproduct of the in-situ reduction reaction is: The ratio of the two is used to calculate a dimensionless index characterizing the healing strength of a unit of powder. The calculation rules are as follows: in, and To obtain the integrated intensity of the characteristic spectral lines of the corresponding elements in real time during the thermal spraying process using a spectrometer, the ceramic shell further contains a colorimetric indicator that is sensitive to redox atmosphere, namely cobalt oxide or manganese oxide. The colorimetric indicator is configured such that when the in-situ reduction reaction occurs successfully, it is reduced to a metallic state in the reducing atmosphere inside the molten droplet, making the final deposition point appear white; while when the in-situ reduction reaction fails, it reacts with zirconium oxide in an oxidizing atmosphere to form a blue cobalt-zirconium spinel or a brown manganese-zirconium solid solution.

7. The modified high-temperature resistant ceramic-based antioxidant composite coating material according to claim 1, characterized in that, The composite powder comprises, by weight of 100 parts, 85 to 95 parts by weight of a ceramic shell and 5 to 15 parts by weight of a reducing core.

8. The modified high-temperature resistant ceramic-based antioxidant composite coating material according to claim 1, characterized in that, Boron segregated at grain boundaries exists in the form of amorphous or nanocrystalline borate phases.

9. The modified high-temperature resistant ceramic-based antioxidant composite coating material according to claim 1, characterized in that, The metal boride metallurgical bonding layer is a gradient layer, with its composition gradually changing from the boron-rich metal phase near the metal matrix side to the metal boride-rich phase near the ceramic shell side.

10. A method for preparing a modified high-temperature resistant ceramic-based antioxidant composite coating material, characterized in that, The method includes the following steps: Step 1: Provide a modified high-temperature resistant ceramic-based antioxidant composite coating material according to any one of claims 1 to 10 as a spraying raw material; Step 2: Using plasma spraying, the raw material is heated to a molten state and deposited onto the metal substrate. The operating power and gas flow rate of the plasma spraying process are set within a process window that is lower than the parameters required to suppress the oxidation of conventional yttrium-stabilized zirconia powder in transit. The energy input of this process window only needs to meet the condition of completely melting the ceramic shell of the raw material.

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