Pt-doped perovskite ceramic composite material, preparation method and application thereof

Abstract

The present application relates to the technical field of ceramic materials and its preparation, in particular to a kind of Pt doped perovskite ceramic composite material and its preparation method and application.The Pt doped perovskite ceramic composite material provided by the present application uses platinum (Pt) as doped phase, simultaneously combines sol-gel assisted doping method and solid phase method two-step sintering, and evenly distributes Pt in the form of nanoparticle in Sm 0.5 Sr 0.5 ZrO3 Ceramic grain boundary region (forms grain boundary nanometer Pt phase), to realize on the basis of maintaining main phase lattice stability, enhance near-infrared reflection ability, reduce heat radiation absorption;The present application reduces the thermal conductivity of ceramic composite material while improving high temperature stability through the interface regulation effect of grain boundary nanometer Pt phase;The present application constructs Pt nanoparticle in ceramic "grain boundary pinning" to hinder crack propagation, significantly improves the toughness and crack resistance of Pt doped perovskite ceramic composite material, and overcomes the intrinsic brittleness defect of ceramic material.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials and their preparation technology, and in particular to a platinum (Pt) doped perovskite ceramic composite material, its preparation method and application. Background Technology

[0002] Sm of perovskite structure 0.5 Sr 0.5 ZrO3 ceramics are considered a highly promising infrared reflective and heat-insulating material due to their excellent high-temperature stability, low coefficient of thermal expansion, and good chemical inertness.

[0003] However, traditional unmodified Sm 0.5 Sr 0.5 ZrO3 ceramics have two main limitations: First, their infrared reflectivity is low, especially in the near-infrared band (1~2.5 μm) where the reflectivity is only 0.5, which leads to significant thermal radiation penetration damage to the matrix in high-temperature applications; second, this material has high intrinsic brittleness, poor toughness, and weak crack resistance, which seriously restricts its structural integrity and service life under complex thermal stress environments.

[0004] To address the aforementioned issues, enhancing its near-infrared reflectivity and improving its toughness and crack resistance are problems faced by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a Pt-doped perovskite ceramic composite material, its preparation method and application. The Pt-doped perovskite ceramic composite material provided by the present invention has strong near-infrared reflectivity, high toughness and crack resistance.

[0006] This invention provides a Pt-doped perovskite ceramic composite material, comprising perovskite-type Sm 0.5 Sr 0.5 ZrO3 ceramics and doped in perovskite-type Sm 0.5 Sr 0.5 Pt nanoparticles in the grain boundary region of ZrO3 ceramics; these Pt nanoparticles exist in a grain boundary pinning manner, forming a Pt-grain boundary dislocation source structure, distributed in Sm 0.5 Sr 0.5 Grain boundaries of ZrO3 ceramics.

[0007] Preferably, the average particle size of the Pt nanoparticles is 300~500 nm.

[0008] Preferably, the content of Pt nanoparticles in the Pt-doped perovskite ceramic composite material is 5~25 mol.

[0009] This invention also provides a method for preparing a Pt-doped perovskite ceramic composite material, wherein the Pt-doped perovskite ceramic composite material is the Pt-doped perovskite ceramic composite material described in the above-mentioned scheme, comprising the following steps:

[0010] (1) Platinum source, sodium citrate and water were mixed and subjected to complexation reaction, gelation reaction and first calcination in sequence to obtain Pt nanoparticles;

[0011] (2) SrCO3, ZrO2 and Sm2O3 were mixed and subjected to wet ball milling, first drying and second calcination to obtain Sm 0.5 Sr 0.5 ZrO3 ceramics;

[0012] (3) The Pt nanoparticles and Sm 0.5 Sr 0.5 ZrO3 ceramic mixtures were sequentially ball-milled, dried, pressed, pre-sintered, heated, and sintered to obtain the Pt-doped perovskite ceramic composite material. The pre-sintering temperature was 790~810 ℃, and the holding time was 1.8~2.1 hours. The heating rate was 4.5~5.5 ℃ / min. The sintering temperature was 1640~1660 ℃, and the holding time was 7~10 hours.

[0013] There is no requirement for the time order of steps (1) and (2).

[0014] Preferably, the sodium citrate and platinum source contain platinum ions (Pt). 4+ The molar ratio of the platinum source to the water is 2-4:1; the molar ratio of the platinum source to the water volume is (0.01-0.05) mol:1 L.

[0015] Preferably, the temperature of the complexation reaction is 78~82 ℃, and the holding time is 1~2 hours; the pH value of the complexation reaction is 5~7.

[0016] Preferably, the gelation reaction is carried out at a temperature of 78~82 ℃ and a holding time of 12~24 hours; the gelation reaction is carried out under static and natural air-drying conditions.

[0017] Preferably, the first calcination temperature is 280~320 ℃, and the holding time is 110~130 minutes; the calcination is carried out in a protective atmosphere.

[0018] Preferably, the second calcination temperature is 1390~1410 ℃, and the holding time is 6~8 hours.

[0019] This invention also provides an application of a Pt-doped perovskite ceramic composite material in a thermal stress environment. The Pt-doped perovskite ceramic composite material is the Pt-doped perovskite ceramic composite material described in the above-described scheme or the Pt-doped perovskite ceramic composite material prepared by the above-described method. The near-infrared reflectivity in the 1.2–2.5 μm wavelength range is increased to over 85%, and the fracture toughness is improved to 11.75 MPa·m. 1 / 2 above.

[0020] This invention provides a Pt-doped perovskite ceramic composite material. The Pt-doped perovskite ceramic composite material provided by this invention uses Pt as the dopant phase and combines a sol-gel assisted doping method with a two-step sintering method to uniformly distribute Pt in the form of nanoparticles on Sm... 0.5 Sr 0.5 ZrO3 ceramic grain boundary regions (forming grain boundary nano-Pt phases) are used to enhance near-infrared reflectivity and reduce thermal radiation absorption while maintaining the stability of the main phase lattice. Figure 8 (As shown in the figure) This invention improves the thermal conductivity stability and thermal shock response of Pt-doped perovskite ceramic composites by the interfacial regulation effect of the grain boundary nano-Pt phase; this invention significantly improves the toughness and crack resistance of Pt-doped perovskite ceramic composites by constructing Pt nanoparticles to "pinneck" cracks at the grain boundaries of ceramics, thus overcoming the intrinsic brittleness of ceramic materials.

[0021] Specifically: in perovskite-type Sm 0.5 Sr 0.5 In the crystal structure of ZrO3 ceramics, Sm and Sr are located at the A-sites, Zr is located at the B-sites, and O forms octahedral coordination. This structure exhibits good thermal stability and optical transparency, but its intrinsic ceramic properties determine its low thermal conductivity, high infrared absorption, and brittleness. Pt, as a high-conductivity, high-density noble metal, has an atomic radius similar to Zr. 4 + 、Sr 2+ Significant differences exist, making it difficult for Pt to stably substitute within the crystal lattice in a large proportion. This invention, by controlling the incorporation of Pt in nanoparticle form, induces Pt particles to segregate to grain boundary regions during sintering, rather than occupying lattice positions. The core principle of this invention lies in the active construction of a "Pt nanoparticle-grain boundary composite structure" through an innovative sol-gel and interface matching method, achieving a synergistic improvement in mechanical and thermo-optical properties at the mesoscale. Specifically, uniformly sized Pt nanoparticles can be controlled and prepared using a sodium citrate-assisted low-temperature reduction method. Subsequently, an interface energy matching and two-step ball milling composite method is used to preferentially anchor the Pt nanoparticles to Sm... 0.5 Sr 0.5On the surface of ZrO3 ceramic powder, during the subsequent low-temperature pre-sintering followed by high-temperature short-time sintering, Pt nanoparticles are displaced and stably pinned to the grain boundary regions of the Pt-doped perovskite ceramic composite material, rather than entering the lattice, thus forming a continuous "grain boundary decoration" structure. At the atomic scale, the introduction of Pt nanoparticles alters the local electron density and phonon propagation paths at the grain boundaries. The outer electrons of Pt atoms are 5d... 9 6s 1 Pt, possessing abundant free electrons, exhibits a strong electromagnetic response in the infrared band, thereby enhancing the infrared radiation reflection performance of Pt-doped perovskite ceramic composites. Furthermore, Pt grain boundary enrichment also improves the thermal conductivity channels at the interface, partially compensating for the intrinsic grain boundary thermal resistance of Pt-doped perovskite ceramic composites and maintaining the overall thermal conductivity stability of the composite material. More importantly, Pt interacts with the surrounding Sm... 0.5 Sr 0.5 The interfaces between ZrO3 ceramic matrices form atomic-level stress gradients, which can induce microstructural defects such as dislocations and stacking faults near grain boundaries. These structures help to blunt crack propagation paths and improve fracture toughness under external loads. The above-mentioned mechanism of the present invention overcomes the problem of poor toughness in Pt-doped perovskite ceramic composites at the atomic scale.

[0022] This invention also provides a method for preparing the Pt-doped perovskite ceramic composite material described above. The Pt-doped perovskite ceramic composite material provided by this invention utilizes Pt nanoparticles doped with perovskite-type Sm... 0.5 Sr 0.5 ZrO3 ceramics endow it with high toughness, high temperature resistance, high reflectivity, and infrared stealth properties. This invention uses Sm... 0.5 Sr 0.5 Using ZrO3 ceramic as a matrix, Pt nanoparticles were incorporated in a specific ratio (5-15 mol%) for doping. Through sol-gel synthesis, high-temperature solid-state synthesis, uniform dispersion treatment, and densification sintering, multiple synergistic optimizations were effectively achieved in Pt-doped perovskite ceramic composites, including improved reflectivity in the near-infrared band, reduced infrared absorption, enhanced thermal conductivity stability, and improved mechanical properties. The introduction of Pt nanoparticles, on the one hand, in Sm 0.5 Sr 0.5 The electronic state modulation effect formed in the ZrO3 ceramic lattice enhances the near-infrared light reflectivity of Pt-doped perovskite ceramic composites, achieving a measured near-infrared reflectivity of over 90%. It exhibits excellent low absorptivity characteristics in the 1.5–2.5 μm band and effectively shields infrared radiation at both room and high temperatures, demonstrating significant infrared stealth and thermal shielding capabilities; specifically, the infrared emissivity in the 2.5–14 μm band is ≤0.3 (room temperature–1000 ℃). The grain boundary nano-Pt phase in Sm... 0.5 Sr0.5 The distribution of ZrO3 ceramic grain boundaries within the matrix effectively suppresses the growth of grain boundary thermal resistance, improving the stability of thermal conductivity at high temperatures. This allows it to maintain a low-fluctuation thermal conductivity curve within the 300–1000 °C temperature range, making it suitable for thermal management and high-temperature protection applications. Furthermore, Pt nanoparticle doping improves the performance of Sm... 0.5 Sr 0.5 The traditional brittleness problem of ZrO3 ceramics is addressed by the addition of Pt nanoparticles, which promotes grain refinement and grain boundary structure regulation, inhibits microcrack propagation and stress concentration, thereby significantly improving the fracture toughness (≥11.75 MPa·m) of Pt-doped perovskite ceramic composites. 1 / 2 The fracture mode gradually shifts from brittle fracture to a ductile-brittle hybrid mode, resulting in superior structural stability and impact resistance in Pt-doped perovskite ceramic composites. This invention provides a ceramic preparation route that achieves synergistic optimization of thermo-optical and mechanical properties through doping control, possessing broad engineering application prospects and market value.

[0023] This invention also provides the application of the Pt-doped perovskite ceramic composite material described in the above-described scheme or the Pt-doped perovskite ceramic composite material prepared by the above-described method in thermal stress environments. The Pt-doped perovskite ceramic composite material provided by this invention exhibits strong near-infrared reflectivity, high toughness and crack resistance, and can overcome harsh conditions in high-temperature or complex thermal stress environments, showing broad application prospects.

[0024] Overall, the present invention achieves the following beneficial effects:

[0025] I. Structural Innovation: The breakthrough of this invention lies in the successful construction of a unique "Pt nanoparticle-grain boundary three-dimensional network" structure. Through the sol-gel method and interface matching approach, Pt nanoparticles with a particle size of 300-500 nm were successfully constructed in Sm... 0.5 Sr 0.5 The precise positioning and uniform distribution of Pt nanoparticles on the grain boundaries of ZrO3 ceramics. This structure is not a simple physical mixture, but rather a continuous three-dimensional grain boundary network structure formed by guiding the directional aggregation of Pt nanoparticles through a specific two-step sintering method. In this network, the Pt nanoparticles simultaneously play an optical function and a mechanical strengthening role, providing microstructural support for improving the overall performance of Pt-doped perovskite ceramic composite materials.

[0026] II. Performance Enhancement: The aforementioned special structure represents a significant breakthrough in the performance of Pt-doped perovskite ceramic composites. In terms of optical properties, the Pt nanoparticles enriched at the grain boundaries enhance the near-infrared reflectivity of the Pt-doped perovskite ceramic composite to >85% in the 1.2–2.5 μm wavelength range through a strong localized surface plasmon resonance effect. In terms of mechanical properties, the Pt nanoparticles, acting as efficient "grain boundary pinning points," significantly improve the fracture toughness of the Pt-doped perovskite ceramic composite to >11.75 MPa·m through crack bridging, deflection, and their own minute plastic deformation. 1 / 2 This successfully solved the inherent brittleness problem of high-performance ceramics. Furthermore, the aforementioned structure creates additional heat transport channels at grain boundaries, ensuring the stability of the thermal conductivity of Pt-doped perovskite ceramic composites at high temperatures. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of this invention, the accompanying drawings used in the embodiments of this invention or in the prior art are briefly described below. For those skilled in the art, other drawings can be derived from the following drawings without creative effort, and all such drawings are within the protection scope of this invention.

[0028] Figure 1 Scanning electron microscope image (a) and statistical particle size distribution histogram (b) of Pt nanoparticles prepared in Example 3;

[0029] Figure 2 Scanning electron microscope image of the Pt-doped perovskite ceramic composite material prepared in Example 3;

[0030] Figure 3 The thermal conductivity comparison diagram is shown between the Pt-doped perovskite ceramic composite material prepared in Example 3 and the single-phase ceramic material prepared in Comparative Example 1.

[0031] Figure 4 The graph shows a comparison of the thermal diffusivity of the Pt-doped perovskite ceramic composite material prepared in Example 3 and the single-phase ceramic material prepared in Comparative Example 1.

[0032] Figure 5 The graph shows a comparison of the average infrared emissivity of the Pt-doped perovskite ceramic composite material prepared in Example 3 and the single-phase ceramic material prepared in Comparative Example 1 at room temperature (a) and high temperature (b).

[0033] Figure 6 The room-temperature infrared reflectance spectra of the Pt-doped perovskite ceramic composite material prepared in Example 3 and the single-phase ceramic material prepared in Comparative Example 1 are shown.

[0034] Figure 7The diagram shows a comparison of the flexural strength and fracture toughness of the Pt-doped perovskite ceramic composite material prepared in Example 3 and the single-phase ceramic material prepared in Comparative Example 1.

[0035] Figure 8 This is a schematic diagram illustrating the working mechanism of the Pt-doped perovskite ceramic composite material provided by the present invention. Detailed Implementation

[0036] This invention provides a Pt-doped perovskite ceramic composite material, comprising perovskite-type Sm 0.5 Sr 0.5 ZrO3 ceramics and doped in perovskite-type Sm 0.5 Sr 0.5 Pt nanoparticles in the grain boundary region of ZrO3 ceramics; these Pt nanoparticles exist in a grain boundary pinning manner, forming a Pt-grain boundary dislocation source structure, distributed in Sm 0.5 Sr 0.5 Grain boundaries of ZrO3 ceramics.

[0037] In this invention, the average particle size of the Pt nanoparticles is preferably 300-500 nm, more preferably 350-450 nm, and even more preferably 400 nm.

[0038] In this invention, the content of Pt nanoparticles in the Pt-doped perovskite ceramic composite material is preferably 5-25 mol%, more preferably 5-15 mol%, and even more preferably 10 mol.

[0039] The Pt-doped perovskite ceramic composite material provided by this invention uses Sm 0.5 Sr 0.5 ZrO3 ceramic is used as the matrix, and 5-15 mol of Pt nanoparticles are incorporated through doping. The Pt nanoparticles are distributed in the Sm... 0.5 Sr 0.5 The grain boundary regions of ZrO3 ceramics are improved, thereby enhancing the thermo-optical and mechanical properties of Pt-doped perovskite ceramic composites. Pt nanoparticles are prepared using a sodium citrate-assisted low-temperature sol-gel reduction method, and then composited with Sm+ through interfacial energy matching and a two-step ball milling process. 0.5 Sr 0.5 The uniform mixing and interfacial bonding of ZrO3 ceramics can effectively improve the near-infrared reflectivity, thermal conductivity and infrared absorption of Pt-doped perovskite ceramic composites, and enhance the toughness of Pt-doped perovskite ceramic composites.

[0040] The Pt-doped perovskite ceramic composite material provided by this invention possesses the following thermo-optical properties: In the near-infrared band of 1.2–2.5 μm, the reflectivity reaches 80–90%; under conditions ranging from room temperature (25 °C) to high temperature (1000 °C), the infrared absorptivity remains ≤20% and is stable with temperature changes, exhibiting low temperature dependence; the thermal conductivity of the Pt-doped perovskite ceramic composite material is stable within the temperature range of 300–1000 °C, with a variation not exceeding 15%, and within this temperature range, its thermal conductivity remains between 1.5 and 2.0 W·m. -1 ·K -1 between.

[0041] This invention also provides a method for preparing a Pt-doped perovskite ceramic composite material, wherein the Pt-doped perovskite ceramic composite material is the Pt-doped perovskite ceramic composite material described in the above-mentioned scheme, comprising the following steps:

[0042] (1) Platinum source, sodium citrate and water were mixed and subjected to complexation reaction, gelation reaction and first calcination in sequence to obtain Pt nanoparticles;

[0043] (2) SrCO3, ZrO2 and Sm2O3 were mixed and subjected to wet ball milling, first drying and second calcination to obtain Sm 0.5 Sr 0.5 ZrO3 ceramics;

[0044] (3) The Pt nanoparticles and Sm 0.5 Sr 0.5 ZrO3 ceramic mixture was subjected to ball milling, second drying, pressing, pre-sintering and sintering in sequence to obtain the Pt-doped perovskite ceramic composite material.

[0045] There is no requirement for the time order of steps (1) and (2).

[0046] This invention involves mixing a platinum source, sodium citrate (Na3C6H5O7·2H2O), and water (denoted as the first mixture) and sequentially performing a complexation reaction, a gelation reaction, and a first calcination to obtain Pt nanoparticles. In this invention, the platinum source is preferably a platinum salt; the platinum salt is preferably sodium hexachloroplatinate; and the sodium hexachloroplatinate is preferably H2PtCl6·6H2O.

[0047] In this invention, the sodium citrate and platinum ions (Pt) in the platinum source 4+ The molar ratio of () is preferably 2 to 4:1, more preferably 3:1.

[0048] In this invention, the water is preferably deionized water.

[0049] In this invention, the molar ratio of the platinum source to the volume of water is preferably (0.01~0.05) mol:1 L, more preferably (0.02~0.04) mol:1 L, and even more preferably 0.03 mol:1 L.

[0050] In this invention, the first mixing preferably includes the following steps: mixing a platinum source and water to obtain a platinum source solution, and then stirring and mixing the platinum source solution with sodium citrate. This invention, through the first mixing, obtains a homogeneous sol.

[0051] In this invention, the temperature of the complexation reaction is preferably 78-82 °C, more preferably 80 °C, and the holding time is preferably 1-2 hours, more preferably 2 hours; the pH value of the complexation reaction is preferably 5-7, more preferably 6. This invention promotes the complexation reaction and preliminary gel formation through the above conditions.

[0052] In this invention, the temperature of the gelation reaction is preferably 78~82 ℃, more preferably 80 ℃, and the holding time is preferably 12~24 hours, more preferably 18 hours; the gelation reaction is preferably carried out under static and natural air-drying conditions; the gelation reaction is preferably carried out in a desiccator.

[0053] In this invention, the gelation reaction preferably includes drying the resulting product; the drying temperature is preferably 55~65 ℃, more preferably 60 ℃, and the holding time is preferably 10~14 hours, more preferably 12 hours.

[0054] In this invention, the preferred calcination temperature is 280~320 °C, more preferably 300 °C, and the preferred holding time is 110~130 minutes, more preferably 120 minutes; the calcination is preferably carried out in a protective atmosphere; the protective atmosphere is preferably nitrogen. This invention uses calcination to reduce Pt nanoparticles, obtaining ferrous metallic Pt nanoparticles.

[0055] In this invention, the first calcination process preferably further includes sonicating the resulting product in ethanol to improve the dispersibility of Pt nanoparticles.

[0056] This invention involves mixing SrCO3, ZrO2, and Sm2O3 and sequentially subjecting them to wet ball milling, a first drying process, and a second calcination to obtain Sm2O3. 0.5 Sr 0.5 ZrO3 ceramics. In this invention, the amounts of SrCO3, ZrO2, and Sm2O3 are preferably calculated according to the ratio of Sm... 0.5 Sr 0.5 The stoichiometric ratio of ZrO3 (the molar ratio of SrCO3, ZrO2 and Sm2O3 is 1:2:1).

[0057] In this invention, the mass fraction of SrCO3, ZrO2 and Sm2O3 is preferably not less than 99.9%.

[0058] In this invention, the conditions for wet ball milling include: the grinding aid is preferably ethanol; the ethanol is preferably anhydrous ethanol; the mass ratio of raw materials (SrCO3, ZrO2, and Sm2O3) to the grinding aid is preferably 1:0.2~1.5, more preferably 1:1; the grinding media is preferably zirconia balls; the ball-to-material ratio is preferably 4~6:1, more preferably 5:1; the ball milling speed is preferably 300~400 rpm, more preferably 350 rpm; and the ball milling time is preferably 10~24 hours, more preferably 16 hours.

[0059] In this invention, the temperature of the first drying is preferably 88~93 ℃, more preferably 90 ℃, and the heat preservation time is preferably 11~13 hours, more preferably 12 hours.

[0060] In this invention, the first drying process preferably includes sieving the resulting product; the sieve aperture is preferably 300 mesh (0.05 mm).

[0061] In this invention, the second calcination temperature is preferably 1390~1410 ℃, more preferably 1400 ℃, and the holding time is preferably 6~8 hours, more preferably 7 hours.

[0062] In this invention, the calcination process preferably includes crushing or grinding the resulting product and then sieving it; the crushing or grinding equipment is preferably a high-speed blender or a mortar and pestle; the sieve aperture is preferably 300 mesh (0.05 mm). This invention obtains a uniform fine powder through crushing and grinding.

[0063] Pt nanoparticles and Sm were obtained 0.5 Sr 0.5 Following ZrO3 ceramics, this invention incorporates the Pt nanoparticles and Sm... 0.5 Sr 0.5 ZrO3 ceramic mixtures are sequentially ball-milled, dried, pressed, pre-sintered, and sintered to obtain the Pt-doped perovskite ceramic composite material. In this invention, the Pt nanoparticles and Sm... 0.5 Sr 0.5 ZrO3 ceramics are preferably selected based on the Pt nanoparticle content in Pt-doped perovskite ceramic composites being 5-25 mol%.

[0064] In this invention, the parameters of the ball milling include: the preferred method is wet ball milling; the preferred grinding aid is ethanol; the preferred ethanol is anhydrous ethanol; the raw materials (Pt nanoparticles and Sm...) 0.5 Sr 0.5The preferred mass ratio of ZrO3 ceramic and grinding aid is 1:0.2~0.3, more preferably 1:0.2; the preferred grinding balls are zirconia grinding balls; the preferred ball-to-material ratio is 4~6:1, more preferably 5:1; the preferred grinding speed is 300~400 rpm, more preferably 350 rpm; the preferred grinding time is 12~24 hours, more preferably 18 hours.

[0065] In this invention, the temperature of the second drying is preferably 88~93 ℃, more preferably 90 ℃, and the heat preservation time is preferably 11~13 hours, more preferably 12 hours.

[0066] In this invention, the second drying process preferably further includes sieving the resulting product; the target pore size of the sieve is preferably 300 mesh (0.05 mm).

[0067] In this invention, the pressed product preferably includes the following steps: pressing and cold isostatic pressing of the dried product in sequence.

[0068] In this invention, the pressing pressure is preferably 9.5~10.5 MPa, more preferably 10 MPa, and the holding time is preferably 2~4 minutes, more preferably 3 minutes. This invention obtains a disc through pressing, the size of which is, for example, [missing information]. 30 mm.

[0069] In this invention, the pressure of the cold isostatic pressing is preferably 190~210 MPa, more preferably 200 MPa, the pressure holding time is preferably 4~6 minutes, more preferably 5 minutes, and the pressure increase time or pressure decrease time is preferably 175~185 seconds, more preferably 180 seconds.

[0070] In this invention, the process of pressing the billet preferably includes allowing the resulting product to stand; the standing time is preferably 12 hours or more, more preferably 12 to 13 hours. This invention releases the internal stress generated during the hydrostatic pressing process by allowing the billet to stand.

[0071] In this invention, the pre-sintering temperature is preferably 790~810 ℃, more preferably 800 ℃, and the holding time is preferably 1.8~2.1 hours, more preferably 2 hours.

[0072] In this invention, the pre-sintering process preferably includes heating; the heating rate is preferably 5.5°C / min.

[0073] In this invention, the sintering temperature is preferably 1640~1660 ℃, more preferably 1650 ℃, and the holding time is preferably 7~10 hours, more preferably 8 hours.

[0074] In this invention, the process before and after sintering preferably includes heating; the heating rate is preferably 4.5°C / min.

[0075] In this invention, the sintering process preferably includes surface polishing of the resulting product; the tool used for surface polishing is preferably sandpaper; the grit of the sandpaper is preferably 80#, 240#, 400#, 800# and 1500#.

[0076] This invention employs a low-temperature pre-sintering + high-temperature short-time sintering method. Pre-sintering removes organic matter and initially forms a grain boundary structure. By controlling the heating rate and the holding time during sintering, the growth of Pt nanoparticles is effectively suppressed, ensuring that they exist stably at the grain boundaries with a particle size of 300~500 nm, forming a "Pt nanoparticle-grain boundary composite structure".

[0077] The preparation method provided by this invention has the advantage of low-cost preparation of Pt nanoparticles; the Pt nanoparticles and ceramics are uniformly mixed (interface matching). In the Pt-doped perovskite ceramic composite material prepared by this invention, the Pt nanoparticles exist in the form of "grain boundary pinning," which improves the microstructure of the Pt-doped perovskite ceramic composite material and forms a special "Pt nanoparticle-grain boundary dislocation source" structure. Under stress, this structure can stimulate dislocation multiplication and slip, absorb crack propagation energy, and improve the fracture toughness to >11.75 MPa·m. 1 / 2 The fracture mode changes from pure brittle to a ductile-brittle hybrid, making it suitable for high-temperature or high-impact environments.

[0078] In the microstructure of the Pt-doped perovskite ceramic composite material prepared by this invention, Pt nanoparticles are uniformly distributed in a grain boundary pinning structure on Sm 0.5 Sr 0.5 The pinning structure, located at the grain boundaries of ZrO3 ceramics rather than dissolved within the crystal lattice, effectively suppresses grain boundary migration and abnormal grain growth. It also controls the average particle size of Pt nanoparticles to 300-500 nm by deflecting the crack path through the stress field, resulting in uniform and stable morphology.

[0079] In the Pt-doped perovskite ceramic composite material prepared by this invention, Pt nanoparticles enhance near-infrared reflectivity through the synergistic effect of surface plasmon resonance and interface scattering. Pt nanoparticles form localized surface plasmon resonance structures at grain boundaries, enhancing the reflection of infrared photons. This results in the Pt-doped perovskite ceramic composite material having an infrared reflectivity ≥90% in the 200~2500nm band and an infrared emissivity ≤0.3 in the 2.5~14μm band (room temperature~1000℃).

[0080] This invention also provides an application of a Pt-doped perovskite ceramic composite material in a thermal stress environment. The Pt-doped perovskite ceramic composite material is the Pt-doped perovskite ceramic composite material described in the above-described scheme or the Pt-doped perovskite ceramic composite material prepared by the above-described method. The near-infrared reflectivity in the 1.2–2.5 μm wavelength range is increased to over 85%, and the fracture toughness is improved to 11.75 MPa·m. 1 / 2 above.

[0081] The Pt-doped perovskite ceramic composite material provided by this invention has strong near-infrared reflectivity, high toughness and crack resistance, and can overcome harsh conditions such as high temperature or complex thermal stress environment, and has broad application prospects.

[0082] To further illustrate the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments.

[0083] Example 1:

[0084] This embodiment prepares a Pt-doped perovskite ceramic composite material, wherein Pt nanoparticles are doped at 5 mol%, and the particle size of the Pt nanoparticles is between 330 and 510 nm, with an average particle size of 414.88 nm. The specific steps are as follows:

[0085] (1) Preparation of Pt nanoparticles:

[0086] Using the sol-gel method, according to Pt 4+ Sodium citrate and hexachloroplatinic acid were weighed out in a molar ratio of 1:4. The hexachloroplatinic acid powder was dissolved in deionized water to obtain a 0.03 mol / L hexachloroplatinic acid solution. Sodium citrate was then slowly added to the prepared hexachloroplatinic acid solution, and the mixture was heated and magnetically stirred, maintaining the pH between 5 and 7 to obtain a stable organometallic complex solution. The prepared organometallic complex solution was heated to 80 °C and stirred continuously for 2 hours until it became viscous and transformed into a homogeneous sol. Stirring was then stopped, and the solution was allowed to air dry for 12 hours to form a gel. The prepared gel was dried at 60 °C for 12 hours to obtain a gray dry gel block. The dry gel block was calcined at 300 °C for 2 hours under a nitrogen atmosphere to reduce the concentration of Pt nanoparticles, yielding black Pt nanoparticles. The black Pt nanoparticles were ultrasonicated in ethanol to improve their dispersibility, resulting in Pt nanoparticles.

[0087] (2) Diffuse phase Sm 0.5 Sr 0.5 Preparation of ZrO3 ceramic powder:

[0088] Solid-state sintering method was adopted, according to Sm 0.5 Sr0.5 The ZrO3 stoichiometric ratio (molar ratio of SrCO3, ZrO2, and Sm2O3 is 1:2:1) was determined by weighing SrCO3, ZrO2, and Sm2O3. The weighed powders were then mixed with anhydrous ethanol and zirconium oxide grinding balls at a mass ratio of 1:0.2:4 in a ball mill jar and ball-milled at 400 rpm for 24 hours to obtain a metal oxide powder mixture slurry. This slurry was dried at 90 °C for 12 hours to obtain a uniformly mixed metal oxide powder. The dried metal oxide powder was then sieved through a 300-mesh sieve and calcined at 1400 °C for 6 hours to obtain Sm2O3. 0.5 Sr 0.5 ZrO3 ceramic powder. Sm 0.5 Sr 0.5 ZrO3 ceramic powder was crushed using a high-speed blender and then sieved through a 300-mesh sieve to obtain the dispersed phase Sm. 0.5 Sr 0.5 ZrO3 ceramic powder.

[0089] (3) Preparation of Pt-doped perovskite ceramic composite materials:

[0090] Using solid-state sintering, Pt nanoparticles and dispersed Sm were weighed out according to a Pt nanoparticle doping ratio of 5 mol%. 0.5 Sr 0.5 ZrO3 ceramic powder was mixed with anhydrous ethanol and zirconium oxide grinding balls at a mass ratio of 1:0.2:4 in a ball mill jar and ball-milled at 400 rpm for 24 hours to obtain a ceramic powder slurry. The ceramic powder slurry was dried at 90 °C for 12 hours to obtain a uniformly mixed ceramic powder. The dried ceramic powder was sieved through a 300-mesh sieve. The sieved ceramic powder was then placed in a mold and pressed into a block at 10 MPa for 3 minutes. This block was then further pressed using a cold isostatic press, with a maximum pressure of 200 MPa, a holding time of 5 minutes, and a pressure increase / decrease time of 180 seconds. The cold isostatically pressed block was heated to 800 °C at a heating rate of 5.5 °C / min and pre-sintered at 800 °C for 2 hours. Then, the temperature was increased to 1650 °C at a heating rate of 4.5 °C / min and sintered at 1650 °C for 10 hours to obtain a dense block ceramic. The surface of the bulk ceramic was polished with sandpaper of grits 80#, 240#, 400#, 800#, and 1500# to ensure a uniform surface finish. This yielded a Pt-doped perovskite ceramic composite material, denoted as Sm. 0.5 Sr 0.5 ZrO3@5 mol.

[0091] Example 2:

[0092] This embodiment prepares a Pt-doped perovskite ceramic composite material, wherein Pt nanoparticles are doped at 10 mol%, and the particle size of the Pt nanoparticles is between 330 and 510 nm, with an average particle size of 414.88 nm. The specific steps are as follows:

[0093] (1) Preparation of Pt nanoparticles:

[0094] Using the sol-gel method, according to Pt 4+ Sodium citrate and hexachloroplatinic acid were weighed out in a molar ratio of 1:4. The hexachloroplatinic acid powder was dissolved in deionized water to obtain a 0.03 mol / L hexachloroplatinic acid solution. Sodium citrate was then slowly added to the hexachloroplatinic acid solution while heating and magnetic stirring, maintaining the pH between 5 and 7 to obtain a stable organometallic complex solution. The organometallic complex solution was heated to 80 °C and stirred continuously for 2 hours until it became viscous and transformed into a homogeneous sol. Stirring was then stopped, and the solution was allowed to air dry for 12 hours to form a gel. The gel was dried at 60 °C for 12 hours to obtain a gray dry gel block. The dry gel block was pyrolyzed at 300 °C for 2 hours under a nitrogen atmosphere to reduce the powder, yielding black Pt nanoparticles. The black Pt nanoparticles were then sonicated in ethanol to further improve the dispersibility of the Pt nanoparticles, resulting in Pt nanoparticles.

[0095] (2) Diffuse phase Sm 0.5 Sr 0.5 Preparation of ZrO3 ceramic powder:

[0096] Solid-state sintering method was adopted, according to Sm 0.5 Sr 0.5 The ZrO3 stoichiometric ratio (molar ratio of SrCO3, ZrO2, and Sm2O3 is 1:2:1) was determined by weighing SrCO3, ZrO2, and Sm2O3. The weighed metal oxide powders were then mixed with anhydrous ethanol and zirconium oxide grinding balls at a mass ratio of 1:0.2:4 in a ball mill jar and ball-milled at 400 rpm for 24 hours to obtain a metal oxide powder slurry. The metal oxide powder slurry was dried at 90 °C for 12 hours to obtain a uniformly mixed metal oxide powder. The dried metal oxide powder was then sieved through a 300-mesh sieve. Finally, the sieved metal oxide powder was calcined at 1400 °C for 6 hours to obtain Sm2O3. 0.5 Sr 0.5 ZrO3 ceramic powder. Sm 0.5 Sr 0.5 ZrO3 ceramic powder was crushed using a high-speed blender and then sieved through a 300-mesh sieve to obtain the dispersed phase Sm. 0.5 Sr 0.5 ZrO3 ceramic powder.

[0097] (3) Preparation of Pt-doped perovskite ceramic composite materials:

[0098] Using solid-state sintering, Pt nanoparticles and dispersed Sm were weighed according to a Pt nanoparticle doping ratio of 10 mol%. 0.5 Sr 0.5 ZrO3 ceramic powder was mixed with anhydrous ethanol and zirconium oxide grinding balls at a mass ratio of 1:0.2:4 in a ball mill jar and ball-milled at 400 rpm for 24 hours to obtain a ceramic powder slurry. The ceramic powder slurry was dried at 90℃ for 12 hours to obtain a uniformly mixed ceramic powder. The dried ceramic powder was sieved through a 300-mesh sieve. The sieved ceramic powder was then placed in a mold and cold-pressed into a block at 10 MPa for 3 minutes. This block was then further pressed using a cold isostatic press, with a maximum pressure of 200 MPa, a holding time of 5 minutes, and a pressure increase / decrease time of 180 seconds. The cold-isostatically pressed block was heated to 800℃ at a heating rate of 5.5℃ / min and pre-sintered at 800℃ for 2 hours. Then, the temperature was increased to 1650℃ at a heating rate of 4.5℃ / min and sintered at 1650℃ for 10 hours to obtain a dense block ceramic. The surface of the bulk ceramic was polished with sandpaper of grits 80#, 240#, 400#, 800#, and 1500# to ensure a uniform surface finish. This yielded a Pt-doped perovskite ceramic composite material, denoted as Sm. 0.5 Sr 0.5 ZrO3@10 mol.

[0099] Example 3:

[0100] This embodiment prepares a Pt-doped perovskite ceramic composite material, wherein Pt nanoparticles are doped at 25 mol%, the particle size of the Pt nanoparticles is between 330 and 510 nm, and the average particle size is 414.88 nm. The specific steps are as follows:

[0101] (1) Preparation of Pt nanoparticles:

[0102] Using the sol-gel method, according to Pt 4+Sodium citrate and hexachloroplatinic acid were weighed out in a molar ratio of 1:4. The hexachloroplatinic acid powder was dissolved in deionized water to obtain a 0.03 mol / L hexachloroplatinic acid solution. Sodium citrate was then slowly added to the hexachloroplatinic acid solution while heating and magnetic stirring, maintaining the pH between 5 and 7 to obtain a stable organometallic complex solution. The organometallic complex solution was heated to 80 °C and stirred continuously for 2 hours until it became viscous and transformed into a homogeneous sol. Stirring was then stopped, and the solution was allowed to air dry for 12 hours to form a gel. The gel was dried at 60 °C for 12 hours to obtain a gray dry gel block. The dry gel block was pyrolyzed at 300 °C for 2 hours under a nitrogen atmosphere to reduce the concentration of Pt nanoparticles, yielding black Pt nanoparticles. The black Pt nanoparticles were then sonicated in ethanol to further improve the dispersibility of the Pt nanoparticles, resulting in Pt nanoparticles.

[0103] (2) Diffuse phase Sm 0.5 Sr 0.5 Preparation of ZrO3 ceramic powder:

[0104] Solid-state sintering method was adopted, according to Sm 0.5 Sr 0.5 The ZrO3 stoichiometric ratio (molar ratio of SrCO3, ZrO2, and Sm2O3 is 1:2:1) was determined by weighing SrCO3, ZrO2, and Sm2O3. The weighed metal oxide powders were then mixed with anhydrous ethanol and zirconium oxide grinding balls at a mass ratio of 1:0.2:4 in a ball mill jar and ball-milled at 400 rpm for 24 hours to obtain a metal oxide powder slurry. This slurry was dried at 90 °C for 12 hours to obtain a uniformly mixed metal oxide powder. The dried metal oxide powder was then sieved through a 300-mesh sieve. Finally, the sieved metal oxide powder was calcined at 1400 °C for 6 hours to obtain Sm2O3. 0.5 Sr 0.5 ZrO3 ceramic powder. Sm 0.5 Sr 0.5 ZrO3 ceramic powder was crushed using a high-speed blender and then sieved through a 300-mesh sieve to obtain the dispersed phase Sm. 0.5 Sr 0.5 ZrO3 ceramic powder.

[0105] (3) Preparation of Pt-doped perovskite ceramic composite materials:

[0106] Using solid-state sintering, Pt nanoparticle powder and dispersed Sm were weighed according to a Pt nanoparticle doping ratio of 25 mol%. 0.5 Sr 0.5ZrO3 ceramic powder was mixed with anhydrous ethanol and zirconium oxide grinding balls at a mass ratio of 1:0.2:4 in a ball mill jar and ball-milled at 400 rpm for 24 hours to obtain a ceramic powder slurry. The ceramic powder slurry was dried at 90 °C for 12 hours to obtain a uniformly mixed ceramic powder. The dried ceramic powder was sieved through a 300-mesh sieve. The sieved ceramic powder was then placed in a mold and cold-pressed into a block at 10 MPa for 3 minutes. This block was then further pressed using a cold isostatic press, with a maximum pressure of 200 MPa, a holding time of 5 minutes, and a pressure increase / decrease time of 180 seconds. The cold-isostatically pressed block was heated to 800 °C at a heating rate of 5.5 °C / min and pre-sintered at 800 °C for 2 hours. Then, the temperature was increased to 1650 °C at a heating rate of 4.5 °C / min and sintered at 1650 °C for 10 hours to obtain a dense block ceramic. The surface of the bulk ceramic was polished with sandpaper of grits 80#, 240#, 400#, 800#, and 1500# to ensure a uniform surface finish. This yielded a Pt-doped perovskite ceramic composite material, denoted as Sm. 0.5 Sr 0.5 ZrO3@25 mol.

[0107] Comparative Example 1:

[0108] This comparative example prepared a single-phase Sm 0.5 Sr 0.5 ZrO3 ceramic material, the specific steps are as follows:

[0109] (1) Single-phase Sm 0.5 Sr 0.5 Preparation of ZrO3 ceramic powder:

[0110] Using solid-state sintering, Sm 0.5 Sr 0.5 The ZrO3 stoichiometric ratio (molar ratio of SrCO3, ZrO2, and Sm2O3 is 1:2:1) was determined by weighing SrCO3, ZrO2, and Sm2O3. The weighed metal oxide powders were then mixed with anhydrous ethanol and zirconium oxide grinding balls at a mass ratio of 1:0.2:4 in a ball mill jar and ball-milled at 400 rpm for 24 hours to obtain a metal oxide powder slurry. The metal oxide powder slurry was dried at 90℃ for 12 hours to obtain a uniformly mixed metal oxide powder. The dried metal oxide powder was then sieved through a 300-mesh sieve. The sieved metal oxide powder was then calcined at 1400℃ for 6 hours to obtain Sm2O3. 0.5 Sr 0.5 ZrO3 ceramic powder. Sm 0.5 Sr 0.5ZrO3 ceramic powder was crushed using a high-speed blender and then sieved through a 300-mesh sieve to obtain single-phase Sm. 0.5 Sr 0.5 ZrO3 ceramic powder.

[0111] (2) Single-phase Sm 0.5 Sr 0.5 Preparation of ZrO3 ceramic bulk:

[0112] The single-phase Sm was sintered using a solid-state sintering method. 0.5 Sr 0.5 ZrO3 ceramic powder was mixed with anhydrous ethanol and zirconium oxide grinding balls at a mass ratio of 1:0.2:4 in a ball mill jar and ball-milled at 400 rpm for 24 hours to obtain a ceramic powder slurry. The ceramic powder slurry was dried at 90℃ for 12 hours to obtain a uniformly mixed ceramic powder. The dried ceramic powder was sieved through a 300-mesh sieve. The sieved ceramic powder was then placed into a mold and cold-pressed into a block, which was further pressed using a cold isostatic press. The maximum pressure was 200 MPa, the holding time was 5 minutes, and the pressure increase / decrease time was 180 seconds. The cold isostatically pressed block was heated to 1650℃ at a heating rate of 4.5℃ / min and sintered at 1650℃ for 10 hours to obtain a dense block ceramic. The surface of the bulk ceramic was polished with sandpaper of grits 80#, 240#, 400#, 800#, and 1500# to ensure a uniform surface finish, yielding single-phase Sm. 0.5 Sr 0.5 ZrO3 ceramic bulk.

[0113] Test Example 1:

[0114] The morphology of the Pt nanoparticles prepared in Example 3 of this invention was observed using a scanning electron microscope, and the particle size distribution was statistically analyzed. The results are as follows: Figure 1 As shown.

[0115] according to Figure 1 It can be seen that the Pt nanoparticles prepared by this invention are round and complete, with uniform particle size and no obvious agglomeration. Their particle size distribution is in the range of 330~510 nm, mainly in the range of 370~450 nm, and the average particle size is 414.88 nm. It can be seen that this invention has successfully prepared Pt nanoparticles.

[0116] Test Example 2:

[0117] The Pt-doped perovskite ceramic composite material prepared in Example 3 was observed using a scanning electron microscope, and the results are as follows: Figure 2 As shown. According to Figure 2 It can be seen that Sm 0.5 Sr 0.5ZrO3 ceramic grain stacking, grain boundary connection of Pt nanoparticles forming a three-dimensional grain boundary network structure, and Pt nanoparticles successfully distributed in Sm... 0.5 Sr 0.5 The ZrO3 grain boundaries are filled, and the Pt nanoparticles have a grain size of less than 1 μm, while the matrix phase Sm 0.5 Sr 0.5 The grain size of ZrO3 ceramics is less than 5 μm.

[0118] Test Example 3:

[0119] The thermal conductivity and thermal diffusivity of the Pt-doped perovskite ceramic composite material prepared in Example 3 and the single-phase ceramic material prepared in Comparative Example 1 were tested using an LFA457 laser thermal conductivity meter. The results are as follows: Figures 3-4 As shown.

[0120] according to Figures 3-4 It can be seen that the thermal conductivity and thermal diffusivity of the Pt-doped perovskite ceramic composite material prepared in Example 3 are significantly reduced: its room temperature thermal conductivity is 2.096 W / (m·K), and its high temperature thermal conductivity further decreases to 1.413 W / (m·K); the room temperature thermal diffusivity is 1.396 mm. 2 ·s -1 The high-temperature thermal diffusivity is only 0.653 mm. 2 ·s -1 The decrease in the aforementioned thermophysical parameters provides a foundation for achieving excellent infrared thermal shielding performance in Pt-doped perovskite ceramic composites.

[0121] Test Example 4:

[0122] The infrared emissivity of the Pt-doped perovskite ceramic composite material prepared in Example 3 and the single-phase ceramic material prepared in Comparative Example 1 were measured at room temperature and high temperature using a Bruker VERTEX 70 Fourier transform infrared spectrometer and a high-temperature emissivity meter from Bohai University, respectively. The results are as follows: Figure 5 As shown. According to Figure 5 It can be seen that the Pt-doped perovskite ceramic composite material prepared in Example 3 has a room temperature infrared emissivity of less than 0.2 and a high temperature emissivity of less than 0.3 in the 2.5~5 μm wavelength range, both of which are significantly lower than the single-phase ceramic material prepared in Comparative Example 1.

[0123] Test Example 5:

[0124] Using a Bruker VERTEX 70 Fourier transform infrared spectrometer, the reflectance properties of the Pt-doped perovskite ceramic composite material prepared in Example 3 and the single-phase ceramic material prepared in Comparative Example 1 were tested in the 400–2500 nm wavelength range. The results are as follows: Figure 6 As shown. According to Figure 6 It can be seen that the infrared reflectance of the Pt-doped perovskite ceramic composite material prepared in Example 3 is higher than 0.95 in this wavelength range, which is significantly higher than that of the single-phase ceramic material prepared in Comparative Example 1.

[0125] Test Example 6:

[0126] The mechanical properties of the Pt-doped perovskite ceramic composite material prepared in Example 3 and the single-phase ceramic material prepared in Comparative Example 1 were tested at room temperature using the three-point bending method. An Instron electronic universal testing machine was used with a loading rate of 0.5 mm / min. The results are as follows: Figure 7 As shown. According to Figure 7 It can be seen that the flexural strength of the Pt-doped perovskite ceramic composite material prepared in Example 3 reaches 236 MPa, which is more than 34% higher than the 176 MPa of Comparative Example 1; at the same time, its fracture toughness is 11.85 MPa·m. 1 / 2 It is significantly higher than the 2.32 MPa·m of Comparative Example 1. 1 / 2 Therefore, it can be seen that the doping of Pt nanoparticles effectively improves the brittleness problem of Pt-doped perovskite ceramic composites.

[0127] The embodiments of the present invention have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. All other embodiments obtained by those skilled in the art based on the above embodiments of the present invention without inventive effort are within the protection scope of the present invention.

Claims

1. A Pt-doped perovskite ceramic composite material, characterized in that, Including perovskite-type Sm 0.5 Sr 0.5 ZrO3 ceramics and doped in perovskite-type Sm 0.5 Sr 0.5 Pt nanoparticles in the grain boundary region of ZrO3 ceramics; The Pt nanoparticles exist in a grain boundary pinning manner, forming a Pt-grain boundary dislocation source structure, distributed in Sm 0.5 Sr 0.5 Grain boundaries of ZrO3 ceramics; The average particle size of the Pt nanoparticles is 300~500 nm. The Pt nanoparticle content in the Pt-doped perovskite ceramic composite material is 5-25 mol%. The preparation method of the Pt-doped perovskite ceramic composite material includes the following steps: (1) Platinum source, sodium citrate and water were mixed and subjected to complexation reaction, gelation reaction and first calcination in sequence to obtain Pt nanoparticles; (2) SrCO3, ZrO2 and Sm2O3 were mixed and subjected to wet ball milling, first drying and second calcination to obtain Sm 0.5 Sr 0.5 ZrO3 ceramics; (3) The Pt nanoparticles and Sm 0.5 Sr 0.5 ZrO3 ceramic mixture was subjected to ball milling, second drying, pressing, pre-sintering, heating and sintering in sequence to obtain the Pt-doped perovskite ceramic composite material. The pre-sintering temperature is 790~810℃, and the holding time is 1.8~2.1 hours; The heating rate is 4.5~5.5℃ / min; The sintering temperature is 1640~1660℃, and the holding time is 7~10 hours; There is no requirement for the time order of steps (1) and (2).

2. A method for preparing a Pt-doped perovskite ceramic composite material, wherein the Pt-doped perovskite ceramic composite material is the Pt-doped perovskite ceramic composite material according to claim 1, characterized in that, Includes the following steps: (1) Platinum source, sodium citrate and water were mixed and subjected to complexation reaction, gelation reaction and first calcination in sequence to obtain Pt nanoparticles; (2) SrCO3, ZrO2 and Sm2O3 were mixed and subjected to wet ball milling, first drying and second calcination to obtain Sm 0.5 Sr 0.5 ZrO3 ceramics; (3) The Pt nanoparticles and Sm 0.5 Sr 0.5 ZrO3 ceramic mixture was subjected to ball milling, second drying, pressing, pre-sintering, heating and sintering in sequence to obtain the Pt-doped perovskite ceramic composite material. The pre-sintering temperature is 790~810℃, and the holding time is 1.8~2.1 hours; The heating rate is 4.5~5.5℃ / min; The sintering temperature is 1640~1660℃, and the holding time is 7~10 hours; There is no requirement for the time order of steps (1) and (2).

3. The preparation method according to claim 2, characterized in that, The molar ratio of sodium citrate to platinum ions in the platinum source is 2~4:1; The molar ratio of the platinum source to the volume of water is (0.01~0.05) mol:1L.

4. The preparation method according to claim 2, characterized in that, The complexation reaction is carried out at a temperature of 78~82℃ for 1~2 hours. The pH value of the complexation reaction is 5-7.

5. The preparation method according to claim 2, characterized in that, The gelation reaction is carried out at a temperature of 78~82℃ and the holding time is 12~24 hours. The gelation reaction was carried out under static and natural air-drying conditions.

6. The preparation method according to claim 2, characterized in that, The first calcination temperature is 280~320℃, and the holding time is 110~130 minutes; The calcination is carried out in a protective atmosphere.

7. The preparation method according to claim 2, characterized in that, The second calcination temperature is 1390~1410℃, and the holding time is 6~8 hours.

8. The application of a Pt-doped perovskite ceramic composite material in a thermal stress environment, characterized in that, The Pt-doped perovskite ceramic composite material is the Pt-doped perovskite ceramic composite material according to claim 1 or the Pt-doped perovskite ceramic composite material obtained by the preparation method according to any one of claims 2 to 7. Its near-infrared reflectivity in the 1.2–2.5 μm wavelength range is increased to over 85%, and its fracture toughness is increased to 11.75 MPa·m. 1 / 2 above.

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