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CN-121974721-A - High-entropy hafnate fiber aerogel facing high-temperature thermal protection and preparation method thereof

CN121974721ACN 121974721 ACN121974721 ACN 121974721ACN-121974721-A

Abstract

The invention belongs to the technical field of inorganic fiber material preparation and thermal protection, and discloses high-entropy hafnate fiber aerogel for high-temperature thermal protection and a preparation method thereof. The method comprises the steps of taking a hafnium source and a multi-rare earth chloride (or a hydrate thereof) as metal sources, introducing acetylacetone and triethylamine into an alcohol solvent to form a complex polymer, purifying by a nonpolar solvent such as acetone and the like to obtain a polymer precursor, adding a small amount of spinning auxiliary agent to prepare a spinning solution, carrying out electrostatic spinning in a controlled water vapor environment to enable water vapor to serve as the nonsolvent to induce jet flow to generate phase separation and form a nano-pore fiber precursor, forming a three-dimensional porous network precursor by self-stacking in a fiber collecting process, and calcining in a segmented manner to obtain the defect fluorite type rare earth high-entropy hafnate ceramic core-shell nano-pore fiber aerogel. Compared with the prior art, the invention realizes high-temperature phase stabilization and simultaneously combines low heat conduction (about 97 mW.m ‑1 ·k ‑1 at 1000 ℃) and excellent deformation recovery capability (complete rebound under 98% compressive strain), and is suitable for high-temperature heat insulation, extreme heat protection and other scenes.

Inventors

  • ZHANG YONGSHENG
  • SU YUNFENG
  • FAN HENGZHONG
  • Yue Difan
  • ZHANG QIANGQIANG
  • ZHU XIAOXIA
  • MA XIAOLI
  • FENG YAOFEI
  • HA HAIRONG
  • ZHOU JIANSONG

Assignees

  • 中国科学院兰州化学物理研究所
  • 中国船舶重工集团公司第七0五研究所

Dates

Publication Date
20260505
Application Date
20260209

Claims (10)

  1. 1. The preparation method of the high-entropy hafnate fiber aerogel for high-temperature heat protection is characterized by comprising the following steps of: (1) Dissolving hafnium source chloride and at least five rare earth metal chlorides or hydrates thereof in an alcohol solvent to obtain a metal source solution; (2) Adding acetylacetone and triethylamine into the metal source solution to carry out a complex reaction to obtain a complex product; (3) Purifying the complex product by using a nonpolar solvent to obtain a polymer precursor; (4) Dissolving the polymer precursor in an alcohol solvent, and adding a spinning auxiliary agent to prepare spinning solution; (5) Carrying out electrostatic spinning on the spinning solution in a controlled water vapor environment with the relative humidity of 55% -70%, so that water vapor induces jet flow to generate phase separation to form precursor fibers with a nano-pore structure, and forming three-dimensional porous network fiber precursors by self-stacking in a collecting process; (6) And (3) carrying out sectional calcination on the three-dimensional porous network fiber precursor to obtain the defect fluorite type rare earth high-entropy hafnate ceramic fiber aerogel with the core-shell nano-pore structure.
  2. 2. The method of claim 1, wherein in step (1), the rare earth metal is at least five of lanthanum, cerium, samarium, gadolinium, yttrium, holmium, erbium, ytterbium, thulium, lutetium, and each rare earth element is equimolar or near equimolar.
  3. 3. The method according to claim 1, wherein in the step (2), the molar ratio of the total metal ions in the metal source solution to the acetylacetone and triethylamine is 1 (0.9-1.1): 2-3.
  4. 4. The method of claim 1, wherein in step (3), the nonpolar solvent is one or more of acetone, ethyl acetate, and tetrahydrofuran.
  5. 5. The method of claim 1, wherein in the step (4), the spinning auxiliary agent is polyethylene oxide, and the mass ratio of the spinning auxiliary agent, the polymer precursor and the solvent in the spinning solution is (0.001-0.02): 1 (1-2).
  6. 6. The method according to claim 1, wherein the parameters of the electrostatic spinning in the step (5) are that the voltage is 10-15 kV, the propelling flow is 1-3 mL/h, and the distance from the needle head to the collector is 15-40 cm.
  7. 7. The method of claim 1, wherein the staged calcination of step (6) comprises: the first stage, heating to 150-200 ℃ at 5-10 ℃ per min; the second stage, heating to 900-1000 ℃ at 1-3 ℃ per minute; And in the third stage, the temperature is raised to 1000-1200 ℃ at 5-15 ℃ per minute, the temperature is kept for 10-120 min, and the furnace is cooled.
  8. 8. The method of claim 7, wherein the heat preservation time is prolonged during the heat preservation at 1000-1200 ℃ to cause the fiber sheath to gradually thicken, and the temperature exceeding 1200 ℃ causes the nano-pores to aggregate and coarsen.
  9. 9. The defect fluorite type rare earth high-entropy hafnate ceramic fiber aerogel is characterized by being prepared by adopting the method according to any one of claims 1 to 8, being of a three-dimensional self-supporting communication porous network structure, formed by mutually overlapping and stacking a plurality of ceramic fibers and having a multi-stage pore structure formed by intercommunicating pores among the fibers and pores inside the fibers, wherein the chemical composition of the ceramic fibers is A 2 Hf 2 O 7 , wherein A sites are occupied by at least five rare earth elements together to form a high-entropy solid solution, the diameter of the ceramic fibers is 700-160 nm, the ceramic fibers are of a core-shell structure on the cross section, an outer shell layer is a continuous relatively dense layer, and an inner core layer contains dispersed nano pores.
  10. 10. Use of the ceramic fiber aerogel of claim 9 in high temperature insulation, thermal protection, or thermal shock insulation components.

Description

High-entropy hafnate fiber aerogel facing high-temperature thermal protection and preparation method thereof Technical Field The invention belongs to the technical field of inorganic fiber material preparation and thermal protection, and relates to high-entropy hafnate fiber aerogel for high-temperature thermal protection and a preparation method thereof. Background High entropy ceramics are a class of advanced inorganic materials that co-occupy lattice sites with equimolar or near equimolar amounts of a plurality of principal elements and form single-phase or quasi-single-phase solid solutions. The high entropy effect, lattice distortion effect, diffusion hysteresis effect and cocktail effect brought by the random multi-component occupation are generally superior to the traditional few-component ceramic in the aspects of high-temperature phase stabilization, sintering coarsening resistance, lattice heat conduction reduction and the like, and a new material design path is provided for the thermal insulation and thermal protection materials in extreme thermal environments. Aiming at the heat insulation requirement of higher service temperature upper limit, the intrinsic temperature resistance of a material system is an important factor for determining the service boundary, and the rare earth hafnate system is considered as an important candidate for high-temperature heat protection and heat insulation application due to the fact that hafnium and rare earth elements have higher melting points and good high-temperature structure stability potential, however, the related research and engineering application of the rare earth hafnate and the high-entropy system thereof are mainly concentrated in the forms of powder, blocks or coatings and the like, the systematic research on fiber forms and light heat insulation structures thereof is relatively insufficient, and the popularization and application of the high-temperature resistant system in light heat insulation structural members and heat protection components with complex configurations are limited. At present, the high-entropy ceramic fiber mostly adopts a solution electrostatic spinning combined heat treatment route to realize multi-component introduction and ceramization, such as a plurality of systems such as high-entropy oxide, rare earth zirconate, rare earth niobate/tantalate and the like covered in Chinese patent documents CN113307632A, CN114751737B, CN115467048B and the like, and advances in fiber continuity, component expansion and application scene. However, the prior art is still more focused on the process closed loop of 'spinnable system construction-fiber forming-inorganization', the forming mechanism, scale level and repeatable regulation and control of the microstructure and pore morphology in the fiber are relatively insufficient, so that the structural consistency and performance stability of the material under different process windows still have a further improvement space, and meanwhile, when the material is applied to higher-temperature heat insulation and thermal protection, the material not only needs intrinsic temperature resistance and low lattice heat conduction, but also needs to maintain the cooperative stability of the structure and performance under the conditions of high-temperature long time or heat flux density fluctuation. Thus, there remains a need for a high entropy ceramic fiber manufacturing route that is more suitable for use in high temperature insulation structures to achieve more reliable insulation performance and structural stability over a higher service temperature range. Disclosure of Invention Aiming at the problems that the prior high-entropy ceramic fiber preparation technology focuses on realizing fiber forming and ceramization and is difficult to cooperatively realize 'selection of a higher temperature resistant material system, controllable preparation of a microstructure in a fiber and integrated forming of a three-dimensional light heat insulation structure' in the preparation process, the invention provides a method for preparing high-entropy hafnate core-shell nano-pore ceramic fiber aerogel by steam-induced phase separation electrostatic spinning. The method aims at solving the challenges that the heat insulation efficiency, the high-temperature phase stability and the mechanical reliability of the high-temperature heat insulation material in the prior art are difficult to cooperatively improve. In order to achieve the above purpose, the invention adopts the following technical scheme: The preparation method of the defect fluorite type rare earth high-entropy hafnate core-shell nano-pore ceramic fiber aerogel comprises the following steps: (1) The preparation of the polymer precursor comprises the steps of dissolving hafnium source chloride and at least five rare earth metal chlorides or hydrates thereof in an alcohol solvent to form a metal source solution, adding acetylacetone and triethylamine into