Hollow Ce-YAG-based composite thermal barrier coating material and preparation method and application thereof

Abstract

The application discloses a hollow Ce-YAG-based composite heat-insulating coating material and a preparation method and application thereof, and belongs to the technical field of high-temperature heat protection coating. The raw materials comprise heat-insulating aggregates, film-forming aids and fillers in a mass ratio of (25-35):(55-70):(13-20), wherein the heat-insulating aggregates are (Y 0.98 Ce 0.02 )3Al5O 12 hollow ceramic powder; the film-forming aid is an inorganic silica resin film-forming agent, the raw materials comprise polyborosilazane, coupling agent gamma-aminopropyl triethoxysilane and nano-silicon dioxide in a mass ratio of (40-50):(2-5):(10-15); and the fillers are alumina fiber powder and low-melting-point glass powder. Through the design of the above raw material composition, the hollow ceramic powder provides excellent heat-insulating performance, the inorganic silica resin film-forming agent guarantees film-forming compactness, and the mass ratio is accurately controlled, so that the functions of the raw materials are complementary and the performance is synergistic.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature thermal protection coating technology, specifically relating to a hollow Ce-YAG-based composite thermal insulation coating material, its preparation method, and its application. Background Technology

[0002] The core performance indicators of thermal protective coating materials mainly include low thermal conductivity, high-temperature phase stability, and matching with the thermal expansion coefficient of the substrate. Currently, domestic and international research mainly focuses on inorganic thermal / environmental barrier coating materials, organic polymer materials, and aerogel coatings. The current research status and development trends are analyzed below: Inorganic thermal / environmental barrier coating materials have attracted much attention due to their excellent high-temperature stability, mainly including rare earth tantalates (RETaO4, RE3TaO7, and RETa3O9) and rare earth hexaaluminates (REMA1). 11 O 19 Rare earth cerates (RE2Ce2O7), rare earth silicates (RE2SiO5 and RE2Si2O7), rare earth phosphates (REPO4), rare earth stannates (RE2Sn2O7), perovskite (ABO3), yttrium aluminum garnet (YAG), and rare earth aluminates (RE4Al2O9) are among the most common. Rare earth tantalates (RETaO4) have become a research hotspot in the field of thermal / environmental barrier coatings in recent years due to their intrinsically low thermal conductivity, excellent high-temperature phase stability, and tunable coefficient of thermal expansion. Studies have shown that their thermophysical properties can be further optimized through rare earth element doping and high-entropy design strategies, achieving effective reduction of thermal conductivity and directional control of the coefficient of thermal expansion. However, the above-mentioned inorganic coating materials are mainly prepared by atmospheric plasma spraying (APS) or electron beam physical vapor deposition (EB-PVD) techniques. Due to limitations in the preparation process, the coating thickness is usually no more than 0.5 mm, making it difficult to meet the technical requirements of large cooling gradients (>230℃); when the thickness exceeds 1 mm, the coating bonding strength decreases sharply.

[0003] Organic polymer coating materials (such as polyurethane and epoxy resin) have the advantages of intrinsically low thermal conductivity and low coefficient of thermal expansion, and their preparation process is simple and low-cost. However, their inherent drawback lies in insufficient temperature resistance: when the operating temperature exceeds 200℃, organic polymer materials are prone to thermo-oxidative aging, molecular chain breakage, and ablation failure, making it difficult to meet the requirements for long-term high-temperature service. Even with modification using organic-inorganic hybrid technology, it is still difficult to solve the problems of poor ablation resistance and low service temperature.

[0004] Aerogel coatings possess extremely low thermal conductivity and density, and their temperature resistance and thermal insulation properties vary significantly with different inorganic solid content. However, aerogel coatings generally suffer from fatal defects such as extremely low bonding strength and poor erosion resistance, and are currently mainly used in the field of civil insulation materials.

[0005] In summary, current research on thermal protective coatings still has the following shortcomings: (1) Although inorganic thermal / environmental barrier coating materials have excellent high-temperature stability, they are limited by preparation processes such as atmospheric plasma spraying, resulting in thin coating thickness and insufficient cooling gradient; (2) Although organic polymer coating materials can be prepared into thick coatings, they have poor thermal stability and low service temperature, making it difficult to meet the long-term service requirements of medium-temperature operating conditions; (3) Aerogel coatings have extremely low bonding strength and poor erosion resistance, making them difficult to apply to harsh aerospace service environments. Therefore, it is necessary to develop thermal insulation coating materials with high bonding strength and cooling gradient for high-temperature service environments (greater than or equal to 200℃). Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hollow Ce-YAG based composite thermal insulation coating material, its preparation method and application. It is a high bonding strength and high thermal insulation coating material with a temperature resistance of 200~500℃, which solves the problems of low temperature resistance of organic coatings, low cooling gradient of thermal barrier coatings and low bonding strength of aerogel coatings.

[0007] The objective of this invention is achieved through the following technical solution: The first aspect of this invention is to provide a hollow Ce-YAG-based composite thermal insulation coating material, the raw materials comprising: thermal insulation aggregate, film-forming aid, and filler in a mass ratio of (25~35):(55~70):(13~20), wherein the thermal insulation aggregate is (YAG-based composite material) 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder, the raw materials include: Y2O3, Al2O3 and CeO2; the film-forming aid is an inorganic silica resin film-forming agent, the raw materials include: polyborosilazane, coupling agent γ-aminopropyltriethoxysilane and nano silica in a mass ratio of (40~50):(2~5):(10~15).

[0008] This invention addresses the problems of poor thermal stability and low bonding strength with the substrate in existing heat-insulating coatings by designing a coating composition comprising (Y 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder serves as the thermal insulation framework, inorganic silica resin film-forming agent serves as the binder matrix for the coating material, and fillers are used as auxiliary additives to adjust other properties of the coating. Firstly, this application synthesizes (Y... 0.98 Ce 0.02 )3Al5O 12 By reducing the thermal conductivity of YAG through Ce doping, Ce 3+ Replacing Y in the YAG lattice 3+The solid solubility limit is approximately 7.5%, and the 2% doping concentration of this invention ensures both Ce and 3+ Complete solid solution enters the dodecahedral lattice sites to form a stable single phase, which is then maintained at Ce. 3+ / Ce 4+ The optimal window for dynamic valence equilibrium allows for the simultaneous retention of a certain proportion of Ce in the sintered insulating aggregate. 3+ and Ce 4+ They respectively perform radiative heat dissipation and lattice stabilization functions. Furthermore, Ce... 3+ (Radius approximately 1.14 Å) and Y 3+ A difference in ionic radius of approximately 1.02 Å can cause moderate lattice distortion, increasing the phonon scattering cross section and further reducing the intrinsic thermal conductivity of the material; meanwhile, Ce 3+ The 4f→5d electron transition at high temperatures endows ceramic powder with higher infrared emissivity, allowing some heat to be dissipated through radiation. Ce doping reduces the thermal conductivity of YAG to 2.65 W·m at 500℃. -1 ·K -1 Compared to undoped YAG, the thermal conductivity is reduced by approximately 70-80%, while YAG has a high melting point of 1970℃, exhibits no phase transition at 500℃, and has extremely low oxygen ion permeability, significantly improving the high-temperature thermal insulation performance and structural stability of the coating material. The mass fraction of the added thermal insulation aggregate is set between 25 and 35 parts. A fraction below 20 parts leads to increased thermal conductivity and a significant increase in back temperature, while a fraction above 40 parts easily causes increased internal stress in the coating and a decrease in bonding strength.

[0009] Secondly, the use of inorganic silica resin film-forming agent, with its excellent film-forming properties combined with ultrasonic dispersion technology, results in a dense coating structure and allows for uniform coating preparation via air spraying. This ensures even coating on complex surfaces such as fastener protrusions / recesses, without accumulation or missed areas. As a bonding matrix for the coating, it forms a continuous and dense ceramic resin network, not only imparting good film-forming properties and adhesion to the substrate but also uniformly dispersing hollow aggregates and fillers. The addition amount of film-forming aid is set between 55 and 70 parts by weight. A content below 55 parts leads to a significant decrease in coating bonding strength and uneven coating, while an excessively high content results in insufficient thermal insulation filler and a decline in thermal insulation performance.

[0010] Specifically, the film-forming aid in this application is obtained by dispersing and stirring polyborosilicate (PBSZ), coupling agent γ-aminopropyltriethoxysilane, and nano-silica until homogeneous. This invention uses PBSZ as the main film-forming agent, achieving a ceramicization yield of 63-71.1% at 500℃, forming ultra-high temperature stable SiBNC amorphous ceramics. Compared to SiO2 ceramics formed by ordinary PBSZ, it exhibits higher thermal stability (>1500℃), superior dielectric properties, and oxidation resistance. The high ceramicization yield effectively reduces the risk of coating volume shrinkage and cracking during high-temperature pyrolysis, ultimately resulting in a coating material that combines ultra-high temperature structural stability, excellent high-temperature oxidation resistance, and stable low dielectric properties, maintaining the integrity of the coating structure and function over a long period under harsh high-temperature conditions.

[0011] Finally, regarding the surfaces of metal and other substrates, the interfacial bonding between rare earth insulating aggregates and the substrate suffers from weak adhesion. Relying solely on insulating aggregates or film-forming base materials cannot simultaneously achieve both insulating performance and bonding strength, and it is difficult to balance these two properties. Furthermore, the poor dispersion and compatibility of components within the coating system are problematic. Firstly, the large polarity difference between inorganic rare earth aggregates and organic film-forming base materials leads to weak interfacial bonding, easily forming interfacial defects and weakening both coating adhesion and insulating performance. Secondly, aggregate powders are prone to agglomeration, resulting in uneven dispersion within the base material and inconsistent coating performance. Thirdly, the proportions are difficult to balance; a high aggregate content can cause film embrittlement, while a high base material content results in insufficient insulating effect, ultimately leading to uneven coating structure and performance. This application discovers a synergistic effect between the insulating aggregates and film-forming agents used and amplifies this synergistic effect through formulation ratio control.

[0012] Specifically, the hollow aggregate and film-forming aids of this application form a synergistic effect during preparation and high-temperature service: using polyborosilicate as a film-forming precursor, a SiBNC amorphous ceramic matrix can be formed through room temperature curing and high-temperature ceramization, with a ceramization yield of 63%~71.1% at 500℃; nano-SiO2, after modification with a coupling agent, is uniformly dispersed in the matrix through covalent bonds to construct a composite precursor resin system; the metal hydroxyl groups on the surface of the hollow Ce-YAG insulating aggregate can react with the SiBNC matrix to generate Si-OM chemical bonds, achieving a strong interfacial bond between the aggregate and the matrix. This multiphase composite structure can effectively alleviate the volume shrinkage during the ceramization process and reduce interfacial defects, ultimately resulting in a coating that possesses excellent interfacial bonding strength, ultra-high temperature structural stability, and high-efficiency thermal insulation performance, maintaining the structural integrity and thermal insulation protection function of the coating for a long time under harsh high-temperature service environments.

[0013] Preferably, the (Y) 0.98 Ce 0.02 )3Al5O 12 The hollow ceramic powder has a particle size of 20~80μm and a purity ≥99.9%. It is understandable that even strictly following (Y)...0.98 Ce 0.02 )3Al5O 12 Raw materials are prepared by weighing them according to stoichiometry. Impurities may still be introduced into the raw materials themselves or during the preparation process. Using the above-mentioned high-purity inorganic raw materials can avoid the introduction of impurities that may affect the heat insulation and high-temperature stability of the coating. The inorganic silica resin film-forming agent with appropriate solid content can ensure film formation and the dispersibility of each component of the coating, thus ensuring the forming quality of the coating.

[0014] Preferably, the inorganic silica resin film-forming agent has a solid content of 30-50%. Using an inorganic silica resin film-forming agent with an appropriate solid content can ensure film-forming properties and the dispersibility of each component in the coating, thus ensuring the coating forming quality.

[0015] Preferably, the filler is alumina fiber powder and low-melting-point glass powder, with a mass ratio of alumina fiber powder : low-melting-point glass powder = (5~8) : (8~12). Alumina fiber powder is preferred as the toughening component, as it can construct a three-dimensional fiber skeleton network in the coating. Utilizing its high elastic modulus (approximately 380 GPa) and large aspect ratio (>15), it efficiently dissipates fracture energy through mechanisms such as fiber pull-out, bridging, and crack deflection, significantly absorbing thermal shock energy and improving the coating's impact toughness and thermal shock resistance. When its mass fraction is less than 5 parts, the toughening effect is weak; when it is more than 8 parts, the poor fiber dispersion and increased entanglement and agglomeration lead to increased coating porosity and a significant increase in internal defects.

[0016] Low-melting-point glass powder is preferred as a self-healing filler. The low-melting-point glass powder used in this application is a type of glassy powder with a low softening point, ranging from 200 to 500°C. During the high-temperature service of the coating, the low-melting-point glass powder melts upon heating to form a high-viscosity liquid phase, which fills the pores and microcracks in the coating through viscous flow, achieving coating densification and self-repair of defects; simultaneously, the molten low-melting-point glass powder... 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder and metal substrates exhibit excellent wettability and spreadability, enabling the formation of a dense glassy sealing layer that prevents oxygen from diffusing into the coating, thereby improving the coating's high-temperature oxidation resistance and sealing performance. Low-melting-point glass powder demonstrates good chemical stability, low volatility at high temperatures, and does not undergo harmful chemical reactions with Ce-YAG aggregates.

[0017] More preferably, the alumina fiber powder has a length of 50-150 μm, a diameter of 5-10 μm, and an aspect ratio of (15-30):1; the low-melting-point glass powder has a particle size of 10-30 μm. Using raw materials with the above-mentioned particle size and morphology allows for the close packing of the solid components, reducing internal porosity in the coating. Simultaneously, the alumina fiber powder can be uniformly dispersed to form a tough support, further improving the coating's density and mechanical properties.

[0018] Specifically, the viscosity of the heat insulation coating material is 0.93~0.96 Pa·s, which can ensure good atomization and uniform distribution of filler while achieving effective film formation in a single pass, avoiding common process defects such as sagging, gun clogging and filler protrusion.

[0019] A second aspect of the present invention is to provide a method for preparing the above-mentioned hollow Ce-YAG-based composite thermal insulation coating material, achieving a strong bond between the coating and the substrate and densification of the internal structure of the coating, comprising the following steps: Preparation of insulating aggregate: This application describes the preparation of hollow insulating aggregate by combining solid-phase method and centrifugal spray granulation, according to (Y 0.98 Ce 0.02 )3Al5O 12 Y₂O₃, Al₂O₃, and CeO₂ were weighed according to their stoichiometric ratio and ball-milled in a planetary ball mill for 10-12 hours at a speed of 300-350 r / min. The mixture was then calcined in a high-temperature box furnace at 1400℃ for 5 hours, and after furnace cooling, sieved through a 180-mesh sieve to obtain coarse powder. This coarse powder was granulated using a centrifugal spray granulator with an alcohol content of 20%-60% and a spray nozzle frequency of 33-35 Hz to obtain the (Y₂O₃)₂O₃. 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder.

[0020] This application describes the preparation of hollow insulating aggregate (Y) using a combination of solid-state method and centrifugal spray granulation. 0.98 Ce 0.02 )3Al5O 12 This application finds that the proportion of hollow spheres can be effectively controlled by adjusting the nozzle frequency and solvent type. When the solvent is alcohol with an alcohol content of 20% to 60% and the nozzle frequency is higher than 33Hz, the proportion of hollow spheres in the aggregate is larger. However, when the solvent is changed to alcohol with an alcohol content of more than 60% and the nozzle frequency is 29 to 33Hz, the proportion of solid spheres in the aggregate is larger.

[0021] Raw material pretreatment: the (Y) 0.98 Ce 0.02 )3Al5O 12The hollow ceramic powder and the filler were dried at 100~120℃ for 2~4h to remove moisture. The polyborosilazane, the coupling agent γ-aminopropyltriethoxysilane, and the nano silica were placed in a room temperature dry environment for later use.

[0022] Preparation of film-forming aid: The polyborosilazane, the coupling agent γ-aminopropyltriethoxysilane, and the nano-silica were weighed according to the mass ratio, mixed, and then ultrasonically dispersed at 150-300W for 15-30 minutes under water bath protection at 5-10℃, and stirred until homogeneous to obtain the inorganic silica resin film-forming agent. Ultrasonic dispersion at 150-300W utilizes the ultrasonic cavitation effect to break up the agglomeration of nanoparticles; no organic dispersant needs to be added during the process.

[0023] Preparation of heat-insulating coating material: Weigh the following (Y) according to the mass ratio 0.98 Ce 0.02 )3Al5O 12 The hollow ceramic powder, the inorganic silica resin film-forming agent, and the filler are ultrasonically dispersed at a power of 150-300W for 10-30 minutes under a water bath protection at 5-10℃ to obtain the heat insulation coating material.

[0024] Preferably, the ultrasonic power in both the preparation steps of the film-forming aid and the preparation steps of the heat-insulating coating material is 180W. First, the nano-silica and the coupling agent γ-aminopropyltriethoxysilane are ultrasonically dispersed in a solvent for 15 min; then, polyborosilazane is added and magnetically stirred for 10 min; finally, the (γ-aminopropyltriethoxysilane) is added. 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder, alumina fiber powder, and low-melting-point glass powder are further ultrasonically dispersed for 10-15 minutes, with the temperature controlled at ≤40℃ throughout the entire process. First, nano-SiO2 and the coupling agent γ-aminopropyltriethoxysilane are ultrasonically premixed in a solvent, allowing γ-aminopropyltriethoxysilane to preferentially adsorb onto the SiO2 surface, avoiding premature cross-linking and gelation of PBSZ caused by amino groups when directly mixed with polyborosilazane. Subsequently, PBSZ is added using magnetic stirring to avoid dehydrogenation coupling induced by high-intensity ultrasound. Finally, the ceramic powder and fibers are introduced for final ultrasonic mixing, ensuring that solid fillers of different sizes and densities are uniformly dispersed sequentially, preventing fiber entanglement and powder sedimentation. It is understood that temperature control throughout the process (≤40℃) effectively suppresses the accumulation of ultrasonic cavitation heat and reaction exothermics, maintains a low viscosity state of the system, and ensures the storage stability and film leveling properties of the final coating slurry. A commonly used intermittent ultrasonic mode, such as 5 seconds on, 5 seconds off, can be used to control the system temperature. Furthermore, the stepwise addition and dispersion method is more reasonable and can further shorten the preparation process time.

[0025] A third aspect of the present invention is to provide an application of the above-mentioned hollow Ce-YAG-based composite thermal insulation coating material, wherein the thermal insulation coating material is coated onto the surface of a metal substrate using air spraying technology, and after curing, a thermal insulation coating is formed. The bonding strength of the thermal insulation coating is 5~8MPa, and the back temperature is below 70℃ within a test temperature of 200~500℃ and a test time of 1800s.

[0026] The substrate is pretreated before the heat-insulating coating material is applied, including the following steps: The surface of the metal substrate is roughened using a sandblasting process, with sand particles of 0.1-0.3 mm, preferably 0.15-0.25 mm, to remove oil and dust from the surface and achieve a suitable surface roughness, thereby increasing the physical bonding strength between the coating and the substrate. Subsequently, a layer of diluted polyborosilazane primer is applied and cured at room temperature for 10-20 minutes, typically within 12-18 minutes. The main component of the film-forming aid in this application includes polyborosilazane. Diluting the polyborosilazane improves its fluidity and permeability, and its use as a primer further buffers thermal expansion, ensuring interfacial compatibility during subsequent application of the heat-insulating coating. It is understood that the primer can be diluted using any dilution method acceptable in the art solely for improving fluidity, such as mixing polyborosilazane with anhydrous ethanol at a volume ratio of 1:1.

[0027] Specifically, when spraying the heat-insulating coating material, the spray gun distance is 200-250mm, the spray gun nozzle diameter is 1.3-1.8mm, the spraying pressure is 0.3-0.5MPa, the moving speed is 30-60cm / s, and the spray thickness is 2-3mm. This meets the basic requirements of the heat-insulating coating and prevents sagging or uneven coating, ensuring good bonding strength between the coating materials. Finally, curing at room temperature for 20-24 hours or heating at 80-150℃ for 2-4 hours ensures full cross-linking and curing of the coating, forming a dense and stable coating structure.

[0028] The beneficial effects of this invention are: (1) This invention utilizes hollow Ce-YAG, polyborosilazane-nano SiO2 composite resin film-forming agent, alumina fiber powder, and low-melting-point glass powder as main raw materials to achieve complementary performance and synergistic effect among the functional components: hollow Ce-YAG provides a highly efficient thermal insulation barrier, inorganic silica resin film-forming agent ensures the density of the coating film and the interfacial bonding strength, alumina fiber powder significantly improves the thermal shock resistance of the coating through fiber pull-out and bridging mechanisms, and low-melting-point glass powder generates SiO2 through oxidation reaction during high-temperature service, accompanied by volume expansion, filling microcracks and pores in the coating in situ, achieving dynamic self-healing. Compared with the prior art, the composite thermal insulation coating prepared by this invention has excellent high-temperature thermal insulation, thermal shock resistance, high-temperature self-healing ability, and interfacial bonding strength.

[0029] (2) The coating of the present invention, after multi-component synergistic optimization, can control the back temperature to ≤70℃ and the thermal conductivity to ≤0.3W•m under a high-temperature thermal environment of 500℃. -1 •K -1 The interface bonding strength is ≥6MPa, and the coating thickness can be kept uniform on irregularly shaped surfaces such as protrusions / depressions, without local accumulation or peeling.

[0030] (3) The coating of the present invention is easy to spray and the preparation process is simple and controllable. It can form an effective coating with high bonding strength by using only air spraying process. It is easy to implement in engineering and is suitable for coating the surface of connection and separation devices of different sizes and structures. Attached Figure Description

[0031] Figure 1 This invention (Y) 0.98 Ce 0.02 )3Al5O 12 SEM image of hollow ceramic powder.

[0032] Figure 2 The thermal performance curves of the heat insulation coatings in Examples 1 and 1-6 are shown.

[0033] Figure 3 The graph shows a comparison of the thermal conductivity of the heat insulation coatings in Examples 1-4 at different temperatures.

[0034] Figure 4 The graph shows a comparison of the thermal conductivity of the heat insulation coatings of Example 1 and Comparative Example 3 at different temperatures. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0036] See Figure 1-4 The present invention provides a technical solution: A hollow Ce-YAG-based composite thermal insulation coating material comprises: thermal insulation aggregate, film-forming aid, and filler in a mass ratio of (25~35):(55~70):(13~20), wherein the thermal insulation aggregate is (YAG) 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder, the raw materials include: Y2O3, Al2O3 and CeO2; The film-forming aid is an inorganic silica resin film-forming agent, and the raw materials include: polyborosilazane, coupling agent γ-aminopropyltriethoxysilane, and nano silica in a mass ratio of (40~50):(2~5):(10~15).

[0037] Preferably, the (Y) 0.98 Ce 0.02 )3Al5O 12 The hollow ceramic powder has a particle size of 20~80μm and a purity of ≥99.9%.

[0038] Preferably, the solid content of the inorganic silica resin film-forming agent is 30-50%.

[0039] Preferably, the filler is alumina fiber powder and low melting point glass powder, and the mass ratio of the two is alumina fiber powder: low melting point glass powder = (5~8): (8~12).

[0040] More preferably, the alumina fiber powder has a length of 50~150μm, a diameter of 5~10μm, and an aspect ratio of (15~30):1; the low melting point glass powder has a particle size of 10~30μm.

[0041] Preferably, the viscosity of the heat-insulating coating material is 0.93~0.96 Pa·s.

[0042] A method for preparing the above-mentioned hollow Ce-YAG-based composite thermal insulation coating material includes the following steps: Preparation of insulating aggregate: according to (Y 0.98 Ce 0.02 )3Al5O 12Y₂O₃, Al₂O₃, and CeO₂ were weighed according to their stoichiometric ratio and ball-milled in a planetary ball mill for 10-12 hours at a speed of 300-350 r / min. The mixture was then calcined in a high-temperature box furnace at 1400℃ for 5 hours, furnace-cooled, and sieved through a 180-mesh sieve to obtain coarse powder. This coarse powder was then granulated using a centrifugal spray granulator to obtain the (Y₂O₃)₂O₃. 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder.

[0043] Raw material pretreatment: the (Y) 0.98 Ce 0.02 )3Al5O 12 The hollow ceramic powder and the filler were dried at 100~120℃ for 2~4h to remove moisture. The polyborosilazane, the coupling agent γ-aminopropyltriethoxysilane, and the nano silica were placed in a room temperature dry environment for later use.

[0044] Preparation of film-forming aid: Weigh the polyborosilazane, the coupling agent γ-aminopropyltriethoxysilane and the nano silica according to the mass ratio, mix them, and then ultrasonically disperse them at a power of 150-300W for 15-30 minutes under the protection of a water bath at 5-10℃ to obtain the inorganic silica resin film-forming agent.

[0045] Preparation of heat-insulating coating material: Weigh the following (Y) according to the mass ratio 0.98 Ce 0.02 )3Al5O 12 The hollow ceramic powder, the inorganic silica resin film-forming agent, and the filler are ultrasonically dispersed at a power of 150-300W for 10-30 minutes under a water bath protection at 5-10℃ to obtain the heat insulation coating material.

[0046] Preferably, the ultrasonic power in both the preparation steps of the film-forming aid and the preparation steps of the heat-insulating coating material is 180W. First, the nano-silica and the coupling agent γ-aminopropyltriethoxysilane are ultrasonically dispersed in a solvent for 15 min; then, polyborosilazane is added and magnetically stirred for 10 min; finally, the (γ-aminopropyltriethoxysilane) is added. 0.98 Ce 0.02 )3Al5O 12 The hollow ceramic powder, the alumina fiber powder, and the low melting point glass powder are further ultrasonically dispersed for 10-15 minutes, with the temperature controlled at ≤40℃ throughout the entire process.

[0047] An application of the above-mentioned hollow Ce-YAG-based composite thermal insulation coating material is to coat the thermal insulation coating material onto the surface of a metal substrate using air spraying technology, and form a thermal insulation coating after curing. The bonding strength of the thermal insulation coating is 5~8MPa, and the back temperature is below 70℃ within a test temperature of 200~500℃ and a test time of 1800s.

[0048] Pre-treatment of the substrate before applying the heat-insulating coating material includes the following steps: The surface of the metal substrate is roughened by sandblasting with a particle size of 0.1~0.3mm to remove oil and dust from the surface of the metal substrate. Then, a layer of diluted polyborosilazane primer is brushed on and cured at room temperature for 10~20 minutes.

[0049] Specifically, when spraying the heat-insulating coating material, the spray gun distance is 200~250mm, the spray gun nozzle diameter is 1.3~1.8mm, the spraying pressure is 0.3~0.5MPa, the moving speed is 30~60cm / s, and the spraying thickness is 2~3mm; it is cured at room temperature for 20~24h or heated and cured at 80~150℃ for 2~4h.

[0050] Example 1

[0051] The preparation process and spraying method of the hollow Ce-YAG-based composite thermal insulation coating material in this embodiment 1 are basically the same as those in the specific implementation method, and the specific implementation is as follows: The hollow Ce-YAG-based composite thermal insulation coating material of this embodiment 1 has the following raw material mass ratio: (Y 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder : Inorganic silica resin film-forming agent : Alumina fiber powder : Low melting point glass powder = 25 : 55 : 5 : 8.

[0052] The inorganic silica resin film-forming agent is composed of polyborosilazane, γ-aminopropyltriethoxysilane, and nano silica in a mass ratio of 40:2:10.

[0053] The preparation steps are as follows: Preparation of insulating aggregate: according to (Y 0.98 Ce 0.02 )3Al5O 12 Y₂O₃, Al₂O₃, and CeO₂ were weighed according to their stoichiometric ratio and ball-milled in a planetary ball mill for 10-12 hours at a speed of 300-350 r / min. The mixture was then calcined in a high-temperature box furnace at 1400℃ for 5 hours, furnace-cooled, and sieved through a 180-mesh sieve to obtain coarse powder. This coarse powder was then granulated using a centrifugal spray granulator to obtain the (Y₂O₃)₂O₃. 0.98 Ce 0.02 )3Al5O 12Hollow ceramic powder. Electron microscopy was performed on this hollow ceramic powder; the electron micrograph is shown below. Figure 1 As shown, by Figure 1 It can be seen that ceramic powder with a distinct hollow structure can be obtained by using the raw material formulation and preparation method of this application. The (Y) 0.98 Ce 0.02 )3Al5O 12 The hollow ceramic powder and the filler were dried at 110°C for 3 hours to remove moisture. The polyborosilazane, the coupling agent γ-aminopropyltriethoxysilane, and the nano-silica were then placed in a room temperature dry environment for later use.

[0054] Preparation of film-forming aid: Weigh the polyborosilazane, the coupling agent γ-aminopropyltriethoxysilane and the nano silica according to the mass ratio, mix them, and then ultrasonically disperse them at a power of 150-300W for 15-30 minutes under the protection of a water bath at 5-10℃ to obtain the inorganic silica resin film-forming agent.

[0055] Preparation of film-forming aids and heat-insulating coating materials: (1) Add nano silica (5g) and γ-aminopropyltriethoxysilane (1g) to 20ml of anhydrous ethanol and ultrasonically disperse for 15min at 180W power under ice-water bath protection.

[0056] (2) Add polyborosilicate (20g) and stir magnetically for 10min.

[0057] (3) Add (Y) 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder (25g), alumina fiber powder (5g), and low melting point glass powder (8g) were ultrasonically dispersed for 10 minutes. The temperature was controlled at ≤40℃ throughout the process. The viscosity was adjusted to 0.96 Pa·s.

[0058] Substrate pretreatment: A carbon steel plate of grade Q235B with dimensions of 200mm×200mm×2mm was used as the substrate. It was sandblasted with 0.2mm sand to Ra=8μm, and then a diluted polyborosilazane primer (polyborosilazane: anhydrous ethanol = 1:1) was brushed on and cured at room temperature for 15min.

[0059] Coating preparation: The obtained heat insulation coating material was sprayed onto the above-mentioned metal substrate using air spraying technology. The spray gun nozzle diameter was 1.5 mm, the spraying pressure was 0.4 MPa, the spray gun distance was 220 mm, the moving speed was 45 cm / s, the dry film thickness of a single spray was 1 mm, two coats were sprayed, and the total coating thickness was controlled to be 2 mm with an interval of 30 min between coats. Then it was cured at room temperature for 20 hours.

[0060] Example 2

[0061] The preparation process and spraying method of the hollow Ce-YAG-based composite thermal insulation coating material in Example 2 are consistent with those in Example 1, except that the mass ratio of each raw material is: (Y 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder : Inorganic silica resin film-forming agent : Alumina fiber powder : Low melting point glass powder = 30 : 60 : 6 : 10.

[0062] Example 3

[0063] The preparation process and spraying method of the hollow Ce-YAG-based composite thermal insulation coating material in Example 3 are consistent with those in Example 1, with the only difference being: (Y 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder : Inorganic silica resin film-forming agent : Alumina fiber powder : Low melting point glass powder = 35 : 65 : 8 : 12.

[0064] Example 4

[0065] The raw material formulation and preparation process of the hollow Ce-YAG-based composite thermal insulation coating material in Example 4 are basically the same as those in Example 1. The only difference is that during spraying, the dry film thickness of a single spray is 1.5 mm, two coats are applied, and the total coating thickness is 3 mm.

[0066] Comparative Example 1

[0067] The preparation process and spraying method of the heat insulation coating material in Comparative Example 1 are the same as those in Example 1, except that: no low-melting-point glass powder self-healing filler is added.

[0068] Comparative Example 2

[0069] The preparation process and spraying method of the heat-insulating coating material in Comparative Example 2 are consistent with those in Example 1, the only difference being: the mass ratio of each raw material is: (Y 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder : Inorganic silica resin film-forming agent : Alumina fiber powder : Low melting point glass powder = 20 : 55 : 5 : 8.

[0070] Comparative Example 3

[0071] The preparation process and spraying method of the heat-insulating coating material in Comparative Example 3 are consistent with those in Example 1, the only difference being that undoped hollow Y3Al5O4 is used. 12 Replace (Y) 0.98 Ce 0.02 )3Al5O 12The hollow ceramic powder, the mass ratio of other raw materials, and the preparation process are the same as in Example 1.

[0072] Comparative Example 4

[0073] The raw material formulation and spraying method of the heat insulation coating material in Comparative Example 4 are the same as those in Example 1. The only difference is that a traditional dispersant (LMA-MMA-silane copolymer) is used instead of the dispersant-free ultrasonic dispersion process, and only simple stirring is used. The mass ratio of other raw materials and the preparation process are the same as those in Example 1.

[0074] Comparative Example 5

[0075] The raw materials and preparation process of the heat insulation coating material in Comparative Example 5 are the same as those in Example 1, except that the coating thickness is 4 mm during spraying.

[0076] Comparative Example 6

[0077] The raw materials and preparation process of the heat insulation coating material in Comparative Example 6 are the same as those in Example 1, except that the coating thickness is 1 mm during spraying.

[0078] Test case

[0079] Core performance tests were conducted on the coatings of Examples 1-4 and Comparative Examples 1-6. The tests included: the back surface temperature (°C) of the coatings in Examples 1-4 and Comparative Examples 1-6 at 500°C, thermal conductivity, coating-substrate bonding strength, and coating uniformity on raised surfaces. The test methods were as follows: (1) Back temperature (substrate temperature) test: Fix the gun distance and sample position, place the substrate sample, test the coating surface temperature and back temperature through thermocouple, turn on the hot air gun, the heating rate is 100℃ / min, start timing when the coating surface temperature is 500℃, and keep warm for 10min.

[0080] (2) Thermal conductivity test: The thermal diffusivity of the thermal insulation coating material was determined using a laser thermal conductivity analyzer (LFA, Laser Flash Analyzer, NETZSCH LFA427, Germany). α Archimedes' drainage method for testing coating thermal conductivity ( ρ ), Popular science law for calculating coating heat capacity (C) p According to the formula κ= ρ C p α Calculate the thermal conductivity of the coating ( κ ), and analyze the thermal insulation performance of the coating.

[0081] (3) Adhesion test: The heat insulation coating material is sprayed onto a carbon steel plate substrate with a size of 200mm×200mm×2mm. The adhesion strength is tested using a universal testing machine and the standard test method of ASTM C633–2008 for the adhesion or bonding strength of thermal spray coatings is adopted.

[0082] (4) Coating condition: Visually inspect the coating sample to see if it shows any damage such as cracking, bubbling, or peeling after the test.

[0083] The test results are shown in Table 1-3. Figure 2 , 4 As shown in Table 1, the back temperature (substrate temperature) changes and bonding strength of Examples 1-4 and Comparative Examples 1-6 at a test temperature of 500°C are illustrated. Table 2 and... Figure 2 The table shows the changes in back temperature (substrate temperature) of Examples 1 and Comparative Examples 1-6 at test temperatures of 300-500℃. Figure 3 The thermal conductivity of the heat-insulating coatings of Examples 1 and Comparative Examples 1-4 at different temperatures is shown in the comparison graph.

[0084] Table 1. Backside temperature and adhesion strength of coatings under different conditions at a test temperature of 500℃.

[0085] Table 2. Back temperature of coatings in Examples 1 and Comparative Examples 1-6 at test temperatures of 300~500℃

[0086] Table 3 Thermal conductivity of the insulating coatings of Examples 1 and Comparative Examples 1-4 at different temperatures

[0087] From Tables 1, 2, and 3, Figure 2 , 3 As can be seen from point 4: 1. Compared with Examples 1-3, the thermal insulation coating of this application is within the required range in terms of back temperature at 500℃, thermal conductivity (500℃), bonding strength between coating and substrate, and coating density.

[0088] 2. Compared with Example 1 and Comparative Example 1, the absence of low-melting-point glass powder self-healing filler will cause the long-term thermal insulation performance of the coating to decrease, the thermal conductivity to increase and the bonding strength to decrease under thermal testing.

[0089] 3. Compared with Example 1 and Comparative Example 2, the reduction in the content of hollow ceramic powder led to an increase in the thermal conductivity of the coating, an increase in the internal temperature of the substrate at 500°C, and a decrease in uniformity.

[0090] 4. Compared with Example 1 and Comparative Example 3, replacing Ce-doped YAG with undoped hollow YAG significantly increased the thermal conductivity, and the internal temperature of the substrate increased dramatically at 500°C.

[0091] 5. Compared with Example 1 and Comparative Example 4, the use of traditional dispersants to replace the dispersant-free ultrasonic process resulted in a significant decrease in coating uniformity and a slight reduction in heat insulation and bonding strength.

[0092] 6. Compared with Example 1 and Comparative Example 5, although increasing the coating thickness to 4mm can reduce the internal temperature, the bonding strength between coating molecules is greatly reduced, and the uniformity of the protrusions is severely deteriorated.

[0093] 7. Compared with Example 1 and Comparative Example 6, when the coating thickness is reduced to 1 mm, the thermal insulation temperature difference is significantly reduced, and the internal temperature at 500°C is significantly increased.

[0094] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A hollow Ce-YAG-based composite thermal insulation coating material, characterized in that: Raw materials include: The composition comprises insulating aggregate, film-forming aid, and filler in a mass ratio of (25~35):(55~70):(13~20), wherein the insulating aggregate is (Y 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder, the raw materials include: Y2O3, Al2O3 and CeO2; The film-forming aid is an inorganic silica resin film-forming agent, and the raw materials include: polyborosilazane, coupling agent γ-aminopropyltriethoxysilane, and nano silica in a mass ratio of (40~50):(2~5):(10~15). The filler is alumina fiber powder and low melting point glass powder, and the mass ratio of the two is alumina fiber powder: low melting point glass powder = (5~8): (8~12). The softening point of the low melting point glass powder is 200~500℃.

2. The hollow Ce-YAG-based composite thermal insulation coating material according to claim 1, characterized in that: The (Y) 0.98 Ce 0.02 )3Al5O 12 The hollow ceramic powder has a particle size of 20~80μm and a purity of ≥99.9%.

3. The hollow Ce-YAG-based composite thermal insulation coating material according to claim 1, characterized in that: The inorganic silica resin film-forming agent has a solid content of 30-50%.

4. The hollow Ce-YAG-based composite thermal insulation coating material according to claim 1, characterized in that: The alumina fiber powder has a length of 50~150μm, a diameter of 5~10μm, and an aspect ratio of (15~30):1; the low melting point glass powder has a particle size of 10~30μm.

5. The hollow Ce-YAG-based composite thermal insulation coating material according to claim 1, characterized in that: The viscosity of the heat-insulating coating material is 0.93~0.96 Pa·s.

6. A method for preparing a hollow Ce-YAG-based composite thermal insulation coating material as described in any one of claims 1-5, characterized in that: Includes the following steps: Preparation of insulating aggregate: according to (Y 0.98 Ce 0.02 )3Al5O 12 Y₂O₃, Al₂O₃, and CeO₂ were weighed according to their stoichiometric ratio and ball-milled in a planetary ball mill for 10-12 hours at a speed of 300-350 r / min. The mixture was then calcined in a high-temperature box furnace at 1400℃ for 5 hours, followed by furnace cooling and sieving through a 180-mesh sieve to obtain coarse powder. This coarse powder was then granulated using a centrifugal spray granulator with an alcohol content of 20%-60% and a spray nozzle frequency of 33-35 Hz. 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder; Raw material pretreatment: the (Y) 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder and filler are dried at 100~120℃ for 2~4h to remove moisture. The polyborosilazane, the coupling agent γ-aminopropyltriethoxysilane and the nano silica are placed in a room temperature dry environment for later use. Preparation of film-forming aid: Weigh the polyborosilazane, the coupling agent γ-aminopropyltriethoxysilane and the nano silica according to the mass ratio, mix them, and then ultrasonically disperse them for 15-30 min under the protection of a water bath at 5-10℃ and stir evenly to obtain the inorganic silica resin film-forming agent. Preparation of heat-insulating coating material: Weigh the following (Y) according to the mass ratio 0.98 Ce 0.02 )3Al5O 12 Hollow ceramic powder, the inorganic silica resin film-forming agent, and the filler are ultrasonically dispersed at a power of 150-300W for 10-30 minutes under a water bath protection at 5-10℃ to obtain the heat insulation coating material. When spraying the heat insulation coating material, the spraying thickness is controlled to be 2-3mm.

7. The method for preparing the hollow Ce-YAG-based composite thermal insulation coating material according to claim 6, characterized in that: The ultrasonic power in both the preparation steps of the film-forming aid and the preparation steps of the heat-insulating coating material is 180W. First, the nano-silica and the coupling agent γ-aminopropyltriethoxysilane are ultrasonically dispersed in a solvent for 15 min; then, polyborosilazane is added and magnetically stirred for 10 min; finally, the (Y) 0.98 Ce 0.02 )3Al5O 12 The hollow ceramic powder, the alumina fiber powder, and the low melting point glass powder are further ultrasonically dispersed for 10-15 minutes, with the temperature controlled at ≤40℃ throughout the entire process.

8. The application of a hollow Ce-YAG-based composite thermal insulation coating material as described in any one of claims 1-5, characterized in that: The heat insulation coating material is applied to the surface of a metal substrate using air spraying technology, and the spraying thickness is controlled to be 2-3 mm. After curing, a heat insulation coating is formed. The bonding strength of the heat insulation coating is 5-8 MPa, and the back temperature is below 70°C within a test temperature of 200-500°C and a test time of 1800 s. Pre-treatment of the substrate before applying the heat-insulating coating material includes the following steps: The surface of the metal substrate is roughened by sandblasting with a particle size of 0.1~0.3mm to remove oil and dust from the surface of the metal substrate. Then, a layer of diluted polyborosilazane primer is brushed on and cured at room temperature for 10~20 minutes.

9. The application of the hollow Ce-YAG-based composite thermal insulation coating material according to claim 8, characterized in that: When spraying the heat-insulating coating material, the spray gun distance is 200~250mm, the spray gun nozzle diameter is 1.3~1.8mm, the spraying pressure is 0.3~0.5MPa, and the moving speed is 30~60cm / s; it is cured at room temperature for 20~24h or heated and cured at 80~150℃ for 2~4h.

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