Multi-ion-doped rare earth hafnate ceramic material with high thermal radiation absorption performance under selected wave band and preparation method, design method and application of multi-ion-doped rare earth hafnate ceramic material
By designing and preparing multi-ion-doped rare-earth hafnium salt ceramic materials, the problem of high infrared thermal radiation transmittance of thermal barrier coating materials was solved, achieving high infrared emissivity, low transmittance and high temperature stability over a wide temperature range, thus improving the thermal protection performance of thermal barrier coatings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-01-30
- Publication Date
- 2026-05-01
AI Technical Summary
Existing thermal barrier coating materials have high transmittance to infrared thermal radiation, making it difficult to effectively absorb the broadband thermal radiation energy generated by high-temperature heat sources, thus weakening the thermal protection performance of the coating. Traditional doping methods lack precise design basis and are difficult to improve photon absorption capacity at high temperatures.
By employing multi-ion-doped rare-earth hafnium salt ceramics, and through the regulation of rare-earth energy level structures, combined with Dieke level diagrams and first-principles calculations, the optimal combination of rare-earth ions and doping ratios were screened to prepare multi-ion-doped rare-earth hafnium salt ceramics with pyrochlore or defective fluorite structures. The multi-level synergistic transition system was constructed by utilizing the rare-earth ion orbital energy level effect to enhance infrared thermal radiation absorption performance.
High infrared emissivity, low transmittance, and high-temperature stability were achieved in a wide temperature range and selected bands. The material has an emissivity greater than 0.8 in the 2.5~14μm band and a transmittance less than 0.15 in the 400~2500nm band. After heat treatment at 1500℃ for 100h, it exhibits good phase stability and optical performance changes of less than 5%.
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Abstract
Description
A multi-ion-doped rare-earth hafnium salt ceramic material with high thermal radiation absorption performance in selected wavelength bands, and its preparation method, design method and application. Technical Field
[0001] This invention belongs to the technical field of thermal barrier coating materials, and more specifically relates to a multi-ion-doped rare earth hafnium salt ceramic material with high thermal radiation absorption performance in selected wavelength bands, as well as its preparation method, design method and application. Background Technology
[0002] Currently, thermal barrier coating materials face a key challenge: their intrinsic high transmittance to infrared thermal radiation makes it difficult for the materials to effectively absorb the broadband (from visible light to far infrared) thermal radiation energy generated by high-temperature heat sources, thereby weakening the overall thermal protection performance of the coating.
[0003] Although entropy engineering is considered an effective strategy for controlling material properties, traditional doping methods usually lack precise design basis for ion selection, and therefore cannot stably and universally improve the photon absorption capacity of coatings at high temperatures.
[0004] Against this backdrop, developing a novel multi-ion-doped rare-earth hafnium salt ceramic material that simultaneously possesses high infrared emissivity, low thermal radiation transmittance, and excellent high-temperature stability over a wide temperature range and in selected wavelength bands has become a key technical challenge that urgently needs to be overcome in this field. Summary of the Invention
[0005] The purpose of this invention is to provide a multi-ion-doped rare-earth hafnium salt ceramic material with high thermal radiation absorption performance in selected wavelength bands, as well as its preparation method, design method and application. More specifically, it provides a multi-ion-doped rare-earth hafnium salt high-absorption ceramic material based on rare-earth energy level structure regulation, as well as its preparation method, design method and application, to solve the problems existing in the prior art.
[0006] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of the present invention is to provide a multi-ion-doped rare-earth hafnium salt ceramic material with high thermal radiation absorption performance in a selected wavelength band. The multi-ion-doped rare-earth hafnium salt high-absorption ceramic material has a pyrochlore or defective fluorite structure, with the general formula A₂Hf₂O₇, wherein A is selected from Nd₂. 3+ 、Sm 3+ Eu 3+ Gd 3+ Dy 3+ Ho 3+ Er 3+ Yb 3+ And La in a fully electron-filled state 3+ and Lu 3+ At least two of them.
[0007] The second technical solution of the present invention provides a method for preparing the above-mentioned multi-ion-doped rare earth hafnium oxide ceramic material with high thermal radiation absorption performance in a selected wavelength band. The steps include: mixing rare earth oxides with hafnium oxide, followed by ball milling, drying, sieving, calcining, and crushing to obtain multi-ion-doped rare earth hafnium oxide ceramic precursor powder; pressing the multi-ion-doped rare earth hafnium oxide ceramic precursor powder into sheets, cold isostatically pressing to obtain a green body, and sintering after standing to obtain the multi-ion-doped rare earth hafnium oxide ceramic material with high thermal radiation absorption performance.
[0008] Furthermore, the ball mill operates at a speed of 300-500 rpm for 20-30 hours.
[0009] Optionally, the ball mill rotates at 400 rpm for 24 hours.
[0010] Furthermore, the drying temperature is 80-100℃, and the time is 10-15 hours.
[0011] Optionally, the drying temperature is 90°C and the time is 12 hours.
[0012] Furthermore, the sieving is performed through a 100-200 mesh sieve, preferably 150 mesh.
[0013] Furthermore, the calcination temperature is 1300-1500℃, and the time is 4-8 hours.
[0014] Optionally, the calcination temperature is 1400℃ and the time is 6 hours.
[0015] Furthermore, the pressure for compressing the sheet is 8-12 MPa, and the pressure holding time is 3-6 min.
[0016] Optionally, the pressure for compressing the sheet is 10 MPa, and the pressure holding time is 5 min.
[0017] Furthermore, the pressure of the cold isostatic pressing is 180-250 MPa, and the holding time is 5-10 min.
[0018] Optionally, the pressure of the cold isostatic pressing is 200 MPa, and the holding time is 5 min.
[0019] Furthermore, the settling time is 12-24 hours, preferably 12 hours.
[0020] Furthermore, the sintering temperature is 1600-1700℃, and the time is 8-12h.
[0021] Optionally, the sintering temperature is 1650°C and the time is 10 hours.
[0022] The third technical solution of the present invention provides an application of the above-mentioned multi-ion-doped rare earth hafnium salt ceramic material with high thermal radiation absorption performance in selected bands in the preparation of thermal barrier coatings.
[0023] The fourth technical solution of this invention provides a design method for a multi-ion-doped rare-earth hafnium salt ceramic material with high thermal radiation absorption performance in a selected band, comprising the following steps: S1, determining the target band range of the thermal radiation absorption performance to be regulated; S2, based on the Dieke level diagram, performing multi-ion combination screening, the screening principle being: screening at least one spectrally activated rare-earth ion and at least one crystal field-regulated rare-earth ion for combination; the main characteristic emission peaks of the selected at least two rare-earth ions should cover more than 60% of the target band, and the valley value of the emission peak of any ion pair in the band should not be less than 20% of the peak value; S3, based on the ion combination screened in step S2, calculating the formation energy and band structure of the system under different doping ratios using first-principles calculations, and determining the optimal molar percentage of each rare-earth ion in the multi-ion-doped rare-earth hafnium salt ceramic material with the lowest formation energy and the narrowest band gap as optimization targets.
[0024] Furthermore, the target wavelength range is 0.75-8μm.
[0025] Furthermore, the spectrally activated rare earth ions are rare earth ions with characteristic emission energy levels located within the modulation band range in the Dieke energy level diagram.
[0026] Furthermore, the crystal field-controlled rare earth ions are rare earth ions used to modulate the local crystal field strength of the matrix and actively induce lattice distortion without generating strong competitive emission.
[0027] Furthermore, the rare earth ions are trivalent rare earth ions.
[0028] Optionally, the trivalent rare earth ion is Nd. 3+ 、Sm 3+ Eu 3+ Gd 3+ Dy 3+ Ho 3+ Er 3+ Yb 3+ And La in a fully electron-filled state 3+ and Lu 3+ .
[0029] This invention discloses the following technical effects: Based on the rare earth ion energy level diagram in crystal field theory, this invention uses the rare earth energy level structure as the basis for doping design, and optimizes the molar percentage of dopant ions through first-principles calculations to regulate and modify the infrared thermal radiation performance of rare earth ion-doped hafnium salt thermal barrier coating system. A series of multi-ion-doped modified rare earth hafnium salt ceramic materials with high infrared emissivity, low transmittance, and high-temperature stability in a wide temperature range and customized wavelength band were prepared.
[0030] Based on crystal field theory, this invention utilizes the rare earth ion orbital energy level effect to construct multi-ion doped rare earth hafnium salt ceramic materials with multi-level synergistic enhancement, overcoming the problem that the traditional entropy engineering strategy has an unclear mechanism for regulating the high absorption performance of materials.
[0031] This invention is simple to operate, and the high absorption performance and high temperature stability of multi-ion doped modified rare earth hafnium oxide ceramic materials can be achieved by solid-state sintering, providing a good application prospect for multi-ion doped modified rare earth hafnium oxide ceramic materials with high absorption performance under wide temperature and frequency conditions.
[0032] The multi-ion doped modified rare earth hafnium salt ceramic material prepared by this invention has an emissivity greater than 0.8 in the 2.5~14μm band, a transmittance less than 0.15 in the 400~2500nm band, and is phase stable after heat treatment at 1500℃ for 100h, with optical performance indicators changing by less than 5%. Attached Figure Description
[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 is a SEM image of the materials prepared in Example 1 and Comparative Example 1.
[0034] Figure 2 shows the XRD patterns of the materials prepared in Example 1 and Comparative Example 1.
[0035] Figure 3 is a comparison of the absorption rates of the materials prepared in Example 1 and Comparative Example 1.
[0036] Figure 4 shows the high-temperature emissivity curves and average emissivity comparison of the materials prepared in Example 2 and Comparative Example 2. The left figure is the high-temperature emissivity curve, and the right figure is the average emissivity.
[0037] Figure 5 is a comparison of the transmittance of the materials prepared in Example 1 and Comparative Example 1.
[0038] Figure 6 is a comparison of the transmittance of the materials prepared in Example 1 and Comparative Example 3.
[0039] Figure 7 shows the XRD comparison of the material prepared in Example 1 before and after heat treatment at 1500℃ for 100h.
[0040] Figure 8 is a comparison of the emissivity of the material prepared in Example 1 before and after heat treatment at 1500℃ for 100h.
[0041] Figure 9 is a comparison of the absorption rate of the material prepared in Example 1 before and after heat treatment at 1500℃ for 100h. Detailed Implementation
[0042] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0043] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0044] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0045] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0046] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0047] Unless otherwise specified, all raw materials and reagents involved in the specific embodiments of this invention are commercially available products.
[0048] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.
[0049] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.
[0050] This invention provides a design method for multi-ion-doped rare-earth hafnium salt ceramic materials with high absorption performance. The steps include: S1, determining the control band: determining the target band range of the thermal radiation absorption performance of the material system to be controlled; the maximum band range of the thermal radiation absorption performance of the material system to be controlled is 0.75-8 μm; S2, based on the Dieke level diagram, performing multi-ion combination screening, the screening principle being: selecting at least one spectrally activated rare-earth ion and at least one crystal field-controlled rare-earth ion for combination; the main characteristic emission peaks of the selected at least two rare-earth ions should cover more than 60% of the target band, and the emission peak valley value of any ion pair in this band should not be lower than... The peak value is 20% to ensure the continuity and high intensity of the spectrum; the spectrally activated rare earth ions are rare earth ions with characteristic emission energy levels located in the modulation band range in the Dieke energy level diagram; the crystal field modulated rare earth ions are rare earth ions used to modulate the local crystal field intensity of the matrix and actively induce lattice distortion without generating strong competitive emission; S3, based on the ion combinations screened in step S2, the formation energy and band structure of the system under different doping ratios are calculated using first-principles calculations, with the lowest formation energy and the narrowest band gap as optimization targets, to determine the optimal molar percentage of each rare earth ion in the multi-ion doped rare earth hafnium salt ceramic material; the rare earth ions are trivalent rare earth ions, including Nd 3+ 、Sm 3+ Eu 3+ Gd 3+ Dy 3+ Ho 3+ Er 3+ Yb 3+ And La in a fully electron-filled state 3+ and Lu 3+ .
[0051] S4. Prepare multi-ion-doped rare-earth hafnium carbonate ceramic materials according to the optimal molar percentage of each rare-earth ion determined in step S3. The material selected is a rare-earth hafnium carbonate ceramic with a pyrochlore / defective fluorite structure that has low thermal conductivity, high melting point, no phase transformation at high temperature, and good high-temperature thermal stability. Its general chemical formula is A2Hf2O7, where A is selected from Nd. 3+ 、Sm 3+ Eu 3+ Gd 3+ Dy 3+ Ho 3+ Er 3+ Yb 3+ And La in a fully electron-filled state 3+ and Lu 3+At least two of them are used, and the preparation steps are as shown in Examples 1-4.
[0052] Based on crystal field theory calculations, multi-ion doped rare earth hafnium salt ceramic materials for regulating thermal radiation absorption performance were selected. The design theory of multi-ion doped rare earth hafnium salt ceramic materials is based on the fact that the 4f shell electrons of trivalent rare earth ions are not full and have abundant transition energy levels, which can be used as sites for regulating thermal radiation absorption performance. Therefore, rare earth element doping is selected as the regulation method.
[0053] The selection criteria based on crystal field theory mainly include the regulation of rare earth ion orbital energy level effects, that is, based on the Dieker level diagram, rare earth elements with less overlap between characteristic energy levels are selected.
[0054] In some specific embodiments, the present invention provides a method for preparing multi-ion-doped rare-earth hafnium salt ceramic materials with high thermal radiation absorption performance, the steps of which include: S1, preparing metal oxide powder according to the general formula A2Hf2O7, including HfO2 and rare-earth oxides corresponding to the A site; A is a trivalent rare-earth ion selected from Nd 3+ 、Sm 3+ Eu 3+ Gd 3+ Dy 3+ Ho 3+ Er 3+ Yb 3+ And La in a fully electron-filled state 3+ and Lu 3+ At least two of the following: S2. Metal oxide powder, anhydrous ethanol, and zirconium oxide grinding balls are placed in a ball mill jar at a mass ratio of 1:0.3:6 and ball milled at 300-500 rpm for 20-30 hours to obtain a metal oxide powder mixture slurry; S3. The metal oxide powder mixture slurry is dried at 80-100℃ for 10-15 hours, then sieved through a 100-200 mesh sieve, calcined at 1300-1500℃ for 4-8 hours, and finally crushed using a wall-breaking machine or mortar and sieved through a 150 mesh sieve to obtain multi-ion doped rare earth hafnium salt ceramic precursor powder; S4. Multi-ion doped rare earth hafnium salt ceramic precursor powder is further crushed through a wall-breaking machine or mortar and sieved through a 150 mesh sieve to obtain multi-ion doped rare earth hafnium salt ceramic precursor powder; The precursor powder of multi-ion-doped rare earth hafnium oxide ceramics is cold-pressed into sheets at a pressure of 8-12 MPa for 3-6 min, followed by cold isostatic pressing to obtain a green body at a pressure of 180-250 MPa for 5-10 min. After cold isostatic pressing, the green body is allowed to stand for 12-24 h to release the internal stress during the static pressing process. Then, it is sintered at 1600-1700℃ for 8-12 h. Finally, it is polished with sandpaper of grits of 240#, 400#, 1000#, and 1500# to ensure a consistent surface condition, thus obtaining a multi-ion-doped rare earth hafnium oxide ceramic material with high thermal radiation absorption performance.
[0055] This invention successfully fabricates a multi-ion-doped rare-earth hafnium salt ceramic material with excellent thermal radiation absorption performance over a wide temperature range using a solid-state sintering process. The material's design is based on crystal field theory, introducing various rare-earth ions to construct a multi-level synergistic transition system, effectively enhancing the material's absorption capability for infrared thermal radiation photons in selectable wavelength ranges. The dopant ions form specific energy level structures in the hafnium salt lattice, significantly increasing the electron transition probability and free carrier concentration, thereby synergistically improving the material's intrinsic photon absorption performance in selectable high-temperature wavelength ranges.
[0056] The obtained multi-ion-doped rare-earth hafnium oxide ceramics exhibit high infrared emissivity (greater than 0.8) in the 2.5–14 μm wavelength range and low transmittance (less than 0.15) in the 400–2500 nm wavelength range. After heat treatment at 1500 °C for 100 hours, the material still maintains excellent phase structure stability, with its optical performance indicators changing by less than 5%, achieving the design goal of synergistic optimization of high infrared emissivity, low transmittance, and high-temperature stability over a wide temperature range and selectable wavelength bands.
[0057] Example 1: The preparation steps of multi-ion-doped rare earth hafnium salt ceramic material with high thermal radiation absorption performance include: S1, according to the chemical formula (La 0.25 Sm 0.25 Eu 0.25 Gd 0.25 S1) Prepare metal oxide powders, including La2O3, Sm2O3, Eu2O3, Gd2O3, and HfO2, in a molar ratio of 1:1:1:1:8; S2) Place the metal oxide powders, anhydrous ethanol, and zirconium oxide grinding balls in a ball mill jar at a mass ratio of 1:0.3:6 and ball mill at 400 rpm for 24 hours to obtain a metal oxide powder mixture slurry; S3) Dry the metal oxide powder mixture slurry at 90℃ for 12 hours, then sieve it through a 150-mesh sieve, calcine it at 1400℃ for 6 hours, and finally crush it using a high-speed blender and sieve it through a 150-mesh sieve to obtain a multi-ion doped product. Rare earth hafnium carbonate ceramic precursor powder; S4, the multi-ion doped rare earth hafnium carbonate ceramic precursor powder is cold-pressed into sheets at 10 MPa pressure for 5 min, followed by cold isostatic pressing to obtain a green body. The cold isostatic pressing pressure is 200 MPa, the holding time is 5 min, and the pressure increase / decrease time is 200 s. After the cold isostatic pressing is completed, it is allowed to stand for 12 h to release the internal stress during the static pressing process. Then it is sintered at 1650℃ for 10 h. Finally, it is polished with sandpaper with mesh numbers of 240#, 400#, 1000#, and 1500# in sequence to ensure that its surface condition is consistent, and a multi-ion doped rare earth hafnium carbonate ceramic material with high thermal radiation absorption performance is obtained.
[0058] Example 2: The preparation steps of multi-ion-doped rare-earth hafnium salt ceramic materials with high thermal radiation absorption performance include: S1, according to the chemical formula (La 0.25 Nd 0.25 Sm 0.25 Gd 0.25 Prepare metal oxide powders, including La2O3, Nd2O3, Sm2O3, Gd2O3, and HfO2, in a molar ratio of 1:1:1:1:8; S2, mix the metal oxide powders with anhydrous ethanol and zirconium oxide grinding balls in a ball mill jar at a mass ratio of 1:0.3:6 and ball mill at 400 rpm for 24 hours to obtain a metal oxide powder mixture slurry; S3, dry the metal oxide powder mixture slurry at 90℃ for 12 hours, then sieve it through a 150-mesh sieve, calcine it at 1400℃ for 6 hours, and finally crush it using a high-speed blender and sieve it through a 150-mesh sieve to obtain a multi-ion doped powder. Rare earth hafnium carbonate ceramic precursor powder; S4, the multi-ion doped rare earth hafnium carbonate ceramic precursor powder is cold-pressed into sheets at 10 MPa pressure for 5 min, followed by cold isostatic pressing to obtain a green body. The cold isostatic pressing pressure is 200 MPa, the holding time is 5 min, and the pressure increase / decrease time is 200 s. After the cold isostatic pressing is completed, it is allowed to stand for 12 h to release the internal stress during the static pressing process. Then it is sintered at 1650℃ for 10 h. Finally, it is polished with sandpaper with mesh numbers of 240#, 400#, 1000#, and 1500# in sequence to ensure that its surface condition is consistent, and a multi-ion doped rare earth hafnium carbonate ceramic material with high thermal radiation absorption performance is obtained.
[0059] Example 3: The preparation steps of multi-ion-doped rare earth hafnium salt ceramic materials with high thermal radiation absorption performance include: S1, according to the chemical formula (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2Prepare metal oxide powders, including La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, and HfO2, in a molar ratio of 1:1:1:1:1:10; S2, mix the metal oxide powders with anhydrous ethanol and zirconium oxide grinding balls in a ball mill jar at a mass ratio of 1:0.3:6, and ball mill at 400 rpm for 24 hours to obtain a metal oxide powder mixture slurry; S3, dry the metal oxide powder mixture slurry at 90℃ for 12 hours, then sieve it through a 150-mesh sieve, calcine it at 1400℃ for 6 hours, and finally crush it using a high-speed blender and sieve it through a 150-mesh sieve to obtain... Multi-ion-doped rare-earth hafnium carbonate ceramic precursor powder; S4, the multi-ion-doped rare-earth hafnium carbonate ceramic precursor powder is cold-pressed into sheets at 10 MPa pressure for 5 min, followed by cold isostatic pressing to obtain a green body. The cold isostatic pressing pressure is 200 MPa, the holding time is 5 min, and the pressure increase / decrease time is 200 s. After the cold isostatic pressing is completed, it is left to stand for 12 h to release the internal stress during the static pressing process. Then it is sintered at 1650℃ for 10 h. Finally, it is polished with sandpaper with mesh numbers of 240#, 400#, 1000#, and 1500# in sequence to ensure that its surface condition is consistent, thus obtaining a multi-ion-doped rare-earth hafnium carbonate ceramic material with high thermal radiation absorption performance.
[0060] Example 4: The preparation steps of multi-ion-doped rare earth hafnium salt ceramic materials with high thermal radiation absorption performance include: S1, according to the chemical formula (Nd... 0.25 Sm 0.25 Eu 0.25 Gd 0.25Prepare metal oxide powders, including Nd₂O₃, Sm₂O₃, Eu₂O₃, Gd₂O₃, and HfO₂, in a molar ratio of 1:1:1:1:8; S2, mix the metal oxide powders with anhydrous ethanol and zirconium oxide grinding balls in a ball mill jar at a mass ratio of 1:0.3:6, and ball mill at 400 rpm for 24 hours to obtain a metal oxide powder mixture slurry; S3, dry the metal oxide powder mixture slurry at 90℃ for 12 hours, then sieve it through a 150-mesh sieve, calcine it at 1400℃ for 6 hours, and finally crush it using a high-speed blender and sieve it through a 150-mesh sieve to obtain a multi-ion doped powder. Rare earth hafnium carbonate ceramic precursor powder; S4, the multi-ion doped rare earth hafnium carbonate ceramic precursor powder is cold-pressed into sheets at 10 MPa pressure for 5 min, followed by cold isostatic pressing to obtain a green body. The cold isostatic pressing pressure is 200 MPa, the holding time is 5 min, and the pressure increase / decrease time is 200 s. After the cold isostatic pressing is completed, it is allowed to stand for 12 h to release the internal stress during the static pressing process. Then it is sintered at 1650℃ for 10 h. Finally, it is polished with sandpaper with mesh numbers of 240#, 400#, 1000#, and 1500# in sequence to ensure that its surface condition is consistent, and a multi-ion doped rare earth hafnium carbonate ceramic material with high thermal radiation absorption performance is obtained.
[0061] The preparation steps of the rare earth hafnium salt ceramic material in Comparative Example 1 include: S1, preparing metal oxide powder according to the chemical formula La2Hf2O7, including La2O3 and HfO2, with a molar ratio of 1:2; S2, placing the metal oxide powder, anhydrous ethanol, and zirconium oxide grinding balls into a ball mill jar at a mass ratio of 1:0.3:6, and ball milling at 400 rpm for 24 hours to obtain a metal oxide powder mixture slurry; S3, drying the metal oxide powder mixture slurry at 90℃ for 12 hours, then sieving it through a 150-mesh sieve, calcining it at 1400℃ for 6 hours, and finally crushing it using a wall-breaking machine and sieving it through a 150-mesh sieve. The precursor powder of multi-ion doped rare earth hafnium oxide ceramics was obtained by sieving. S4. The precursor powder of multi-ion doped rare earth hafnium oxide ceramics was cold-pressed into sheets under a pressure of 10 MPa for 5 min. Then, it was cold isostatically pressed to obtain a green body. The pressure of cold isostatic pressing was 200 MPa, the holding time was 5 min, and the pressure increase / decrease time was 200 s. After the cold isostatic pressing was completed, it was allowed to stand for 12 h to release the internal stress during the static pressing process. Then, it was sintered at 1650℃ for 10 h. Finally, it was polished with sandpaper with mesh numbers of 240#, 400#, 1000#, and 1500# in sequence to ensure that its surface condition was consistent, and rare earth hafnium oxide ceramic material was obtained.
[0062] Comparative Example 2: The preparation steps of rare earth hafnium salt ceramic materials include: S1, according to the chemical formula (La... 0.25 Sm 0.25 Gd0.25 Y 0.25 Prepare metal oxide powders, including La2O3, Sm2O3, Gd2O3, Y2O3, and HfO2, in a molar ratio of 1:1:1:1:8; S2, mix the metal oxide powders with anhydrous ethanol and zirconium oxide grinding balls in a ball mill jar at a mass ratio of 1:0.3:6 and ball mill at 400 rpm for 24 hours to obtain a metal oxide powder mixture slurry; S3, dry the metal oxide powder mixture slurry at 90℃ for 12 hours, then sieve it through a 150-mesh sieve, calcine it at 1400℃ for 6 hours, and finally crush it using a high-speed blender and sieve it through a 150-mesh sieve. S4. The multi-ion-doped rare earth hafnium oxide ceramic precursor powder was cold-pressed into sheets at 10 MPa for 5 min, followed by cold isostatic pressing to obtain a green body. The cold isostatic pressing pressure was 200 MPa, the holding time was 5 min, and the pressure increase / decrease time was 200 s. After the cold isostatic pressing was completed, the green body was allowed to stand for 12 h to release the internal stress during the static pressing process. Then it was sintered at 1650℃ for 10 h. Finally, it was polished with sandpaper with mesh numbers of 240#, 400#, 1000#, and 1500# in sequence to ensure that its surface condition was consistent, and rare earth hafnium oxide ceramic material was obtained.
[0063] Comparative Example 3: The preparation steps of rare earth hafnium salt ceramic materials include: S1, according to the chemical formula (La 0.4 Sm 0.2 Eu 0.1 Gd 0.3Prepare metal oxide powders, including La2O3, Sm2O3, Eu2O3, Gd2O3, and HfO2, in a molar ratio of 4:2:1:3:20; S2, mix the metal oxide powders with anhydrous ethanol and zirconium oxide grinding balls in a ball mill jar at a mass ratio of 1:0.3:6, and ball mill at 400 rpm for 24 hours to obtain a metal oxide powder mixture slurry; S3, dry the metal oxide powder mixture slurry at 90℃ for 12 hours, then sieve it through a 150-mesh sieve, calcine it at 1400℃ for 6 hours, and finally crush it using a high-speed blender and sieve it through a 150-mesh sieve. S4. The multi-ion-doped rare earth hafnium oxide ceramic precursor powder was cold-pressed into sheets at 10 MPa for 5 min, followed by cold isostatic pressing to obtain a green body. The cold isostatic pressing pressure was 200 MPa, the holding time was 5 min, and the pressure increase / decrease time was 200 s. After the cold isostatic pressing was completed, the green body was allowed to stand for 12 h to release the internal stress during the static pressing process. Then it was sintered at 1650℃ for 10 h. Finally, it was polished with sandpaper with mesh numbers of 240#, 400#, 1000#, and 1500# in sequence to ensure that its surface condition was consistent, and the rare earth hafnium oxide ceramic material was obtained.
[0064] The transmittance test band in the attached figures below is 400~2500nm, with a sample thickness of 1mm; the absorbance test band is 200~2500nm, with a sample thickness of 2mm; and the emissivity test band is 2.5~14μm, with a sample thickness of 2mm.
[0065] Figure 1 shows SEM images of the materials prepared in Example 1 and Comparative Example 1. As can be seen from the figure, the material prepared in Example 1 has good density and no obvious pores or cracks on its surface. Compared to Comparative Example 1, the grain size of Example 1 is larger and the surface is more dense.
[0066] Figure 2 shows the XRD patterns of the materials prepared in Example 1 and Comparative Example 1. As can be seen from the figure, Example 1 successfully prepared a multi-ion-doped modified rare earth hafnium salt ceramic material with a pyrochlore structure, which has the same phase structure as Comparative Example 1. This indicates that multi-rare earth ion doping can prepare a stable phase structure without generating multiphase.
[0067] The room temperature absorbance of the samples prepared in Example 1 and Comparative Example 1 was measured using a PerkinElmer LAMBDA 750 spectrophotometer, and the results are shown in Figure 3.
[0068] Figure 3 shows a comparison of the absorption rates of the materials prepared in Example 1 and Comparative Example 1. As can be seen from the figure, Example 1 exhibits a significant absorption peak across the entire test wavelength range. When the wavelength is >1000 nm, the absorption rate of Example 1 is significantly higher than that of Comparative Example 1, indicating that Example 1 possesses excellent absorption performance.
[0069] The high-temperature infrared emissivity of the samples prepared in Example 2 and Comparative Example 2 at 400℃ was measured using a high-temperature emissivity meter, and the results are shown in Figure 4.
[0070] Figure 4 shows the high-temperature emissivity curves and average emissivity comparison of the materials prepared in Example 2 and Comparative Example 2. The left figure shows the high-temperature emissivity curve, and the right figure shows the average emissivity. As can be seen from the figure, the emissivity of Example 2 is significantly higher than that of Comparative Example 2 within the test wavelength range, especially in the 2.5-8 μm short-wavelength range. Furthermore, the average emissivity across the entire test wavelength range reaches 0.86, far exceeding the 0.42 of Comparative Example 2. This indicates that Example 2 possesses excellent broadband infrared high absorption performance at high temperatures.
[0071] The room temperature transmittance of the samples prepared in Example 1 and Comparative Example 1 was measured using a PerkinElmer LAMBDA 1050 spectrophotometer, and the results are shown in Figure 5.
[0072] Figure 5 shows a comparison of the transmittance of the materials prepared in Example 1 and Comparative Example 1. As can be seen from the figure, the transmittance of Comparative Example 1 steadily increases with the increase of wavelength, eventually reaching 0.13, while Example 1 has obvious low transmittance peaks and valleys, and its transmittance is significantly lower than 0.1 in most test wavelength ranges, indicating that Example 1 has good low transmittance potential.
[0073] The room temperature transmittance of the samples prepared in Example 1 and Comparative Example 3 was measured using a PerkinElmer LAMBDA 1050 spectrophotometer, and the results are shown in Figure 6.
[0074] Figure 6 shows a comparison of the transmittance of the materials prepared in Example 1 and Comparative Example 3. As can be seen from the figure, the transmittance of Comparative Example 3 is significantly higher than that of Example 1, and the transmittance is significantly higher than 0.1 in most test wavelength ranges, indicating that Example 1 has the optimal rare earth molar ratio.
[0075] The material prepared in Example 1 was heat-treated at 1500℃ for 100h. The XRD patterns before and after heat treatment are shown in Figure 7, the emissivity comparison diagram is shown in Figure 8, and the absorptivity comparison diagram is shown in Figure 9.
[0076] The room-temperature infrared emissivity of the samples before and after heat treatment was measured using a Bruker VERTEX 70 Fourier transform infrared spectrometer; the room-temperature infrared emissivity of the samples before and after heat treatment was measured using a PerkinElmer LAMBDA 750 spectrophotometer.
[0077] Figure 7 shows the XRD patterns of the material prepared in Example 1 before and after heat treatment at 1500℃ for 100h. As can be seen from the figure, the phase of the material in Example 1 did not change after heat treatment at 1500℃ for 100h, indicating that Example 1 has excellent high-temperature stability.
[0078] Figure 8 shows a comparison of the emissivity of the material prepared in Example 1 before and after heat treatment at 1500℃ for 100 hours. As can be seen from the figure, the infrared emissivity of Example 1 did not decrease after heat treatment at 1500℃ for 100 hours, and the change in value was less than 5%, indicating that the thermo-optical properties of Example 1 also have excellent high-temperature stability.
[0079] Figure 9 shows a comparison of the absorption rates of the material prepared in Example 1 before and after heat treatment at 1500℃ for 100 hours. As can be seen from the figure, after heat treatment at 1500℃ for 100 hours, the high absorption peak of Example 1 did not show a significant shift, and the absorption rate did not decrease; the change in value was less than 5%. Combined with the results in Figure 7, this indicates that Example 1 exhibits excellent high-temperature stability in its broadband thermo-optical properties.
[0080] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0081] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A multi-ion-doped rare-earth hafnium salt ceramic material exhibiting high thermal radiation absorption performance in a selected wavelength band, characterized in that, The multi-ion-doped rare-earth hafnium salt high-absorption ceramic material has a pyrochlore or defective fluorite structure, with the general formula A₂Hf₂O₇, where A is selected from Nd. 3+ 、Sm 3+ Eu 3+ Gd 3+ Dy 3+ Ho 3+ Er 3+ Yb 3+ And La in a fully electron-filled state 3+ and Lu 3+ At least two of them.
2. A method for preparing a multi-ion-doped rare-earth hafnium salt ceramic material with high thermal radiation absorption performance in a selected wavelength band, as described in claim 1, characterized in that the steps include... include: Rare earth oxides were mixed with hafnium oxide, and then ball-milled, dried, sieved, calcined, and crushed to obtain multi-ion-doped rare earth hafnium salt ceramic precursor powder. The multi-ion-doped rare-earth hafnium oxide ceramic precursor powder is pressed into sheets, cold isostatically pressed to obtain a green body, and then sintered after standing to obtain the multi-ion-doped rare-earth hafnium oxide ceramic material with high thermal radiation absorption performance.
3. The preparation method according to claim 2, characterized in that, The ball milling speed is 300-500 rpm, and the time is 20-30 h; and / or, the drying temperature is 80-100℃, and the time is 10-15 h.
4. The preparation method according to claim 2, characterized in that, The calcination temperature is 1300-1500℃, and the time is 4-8 hours.
5. The preparation method according to claim 2, characterized in that, The pressure for pressing the sheet is 8-12 MPa, and the holding time is 3-6 min; and / or, the pressure for cold isostatic pressing is 180-250 MPa, and the holding time is 5-10 min.
6. The preparation method according to claim 2, characterized in that, The settling time is 12-24 hours.
7. The preparation method according to claim 2, characterized in that, The sintering temperature is 1600-1700℃ and the time is 8-12h.
8. The application of the multi-ion-doped rare-earth hafnium salt ceramic material with high thermal radiation absorption performance in a selected wavelength band, as described in claim 1, in the preparation of thermal barrier coatings.
9. A design method for a multi-ion-doped rare-earth hafnium salt ceramic material with high thermal radiation absorption performance in a selected wavelength band, as described in claim 1, characterized in that... The steps include: S1. Determine the target wavelength range for the thermal radiation absorption performance that needs to be regulated; S2. Based on the Dieker level diagram, perform multi-ion combination screening. The screening principle is: screen for at least one spectrally activated rare earth ion and at least one crystal field-regulated rare earth ion for combination; the main characteristic emission peaks of the selected at least two rare earth ions should cover more than 60% of the target wavelength range, and the valley value of the emission peak of any ion pair in this wavelength range should not be less than 20% of the peak value; the rare earth ions are trivalent rare earth ions; S3. Based on the ion combinations screened in step S2, calculate the formation energy and band structure of the system under different doping ratios using first-principles calculations. With the lowest formation energy and the narrowest band gap as optimization targets, determine the optimal molar percentage of each rare earth ion in the multi-ion doped rare earth hafnium salt ceramic material.
10. The design method as described in claim 9, characterized in that, The target wavelength range is 0.75-8 μm; and / or, the spectrally activated rare earth ion is a rare earth ion with a characteristic emission energy level located within the modulated wavelength range in the Dieke level diagram; and / or, the crystal field modulated rare earth ion is a rare earth ion used to modulate the local crystal field intensity of the matrix, actively inducing lattice distortion without generating strong competitive emission; and / or, the trivalent rare earth ion is Nd. 3+ 、Sm 3+ Eu 3+ Gd 3+ Dy 3+ Ho 3+ Er 3+ Yb 3+ And La in a fully electron-filled state 3+ and Lu 3+ .