材料科学技术(英文版)2022，Vol.104Issue(9) ：131-144.

Improved thermal stability and infrared emissivity of high-entropy REMgAl11O19 and LaMAl11O19(RE=La,Nd,Gd,Sm,Pr,Dy;M=Mg,Fe,Co,Ni,Zn)

Haolin Zhu Ling Liu Huimin Xiang Fu-Zhi Dai Xiaohui Wang Zhuang Ma Yanbo Liu Yanchun Zhou
材料科学技术(英文版)2022，Vol.104Issue(9) ：131-144.
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Improved thermal stability and infrared emissivity of high-entropy REMgAl11O19 and LaMAl11O19(RE=La,Nd,Gd,Sm,Pr,Dy;M=Mg,Fe,Co,Ni,Zn)

Haolin Zhu 1Ling Liu 2Huimin Xiang 3Fu-Zhi Dai 3Xiaohui Wang 4Zhuang Ma 2Yanbo Liu 2Yanchun Zhou3
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作者信息

  • 1. School of Materials Science and Engineering,Beijing Institute of Technology,Beijing 100081,China;Science and Technology on Advanced Functional Composite Laboratory,Aerospace Research Institute of Materials&Processing Technology,Beijing 100076,China;National Key Laboratory of Science and Technology on Materials under Shock and Impact,Beijing 100081,China
  • 2. School of Materials Science and Engineering,Beijing Institute of Technology,Beijing 100081,China;National Key Laboratory of Science and Technology on Materials under Shock and Impact,Beijing 100081,China;Beijing Institute of Technology Chongqing Innovation Center,Chongqing 401120,China
  • 3. Science and Technology on Advanced Functional Composite Laboratory,Aerospace Research Institute of Materials&Processing Technology,Beijing 100076,China
  • 4. Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China
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Abstract

LaMgAl11O19(LMA),characterized by high melting point,low density and thermal conductivity as well as good infrared emissivity,is regarded as a potential candidate for the thermal protection of hyper-sonic vehicles.Nevertheless,the unsatisfied phase stability at high temperature results in declining of the emissivity below 6 μm,which limits the extensive applications of LaMgAl11O19.In order to overcome this obstacle,three dense bulk high-entropy ceramics,(La0.2Nd0.2Gd0.2Sm0.2Pr0.2)MgAl11O19(HE LMA-1),(La0.2Nd0.2Gd0.2Sm0.2Dy0.2)Mg Al11O19(HE LMA-2)and La(Mg0.2Fe0.2Co0.2Ni0.2Zn0.2)Al11O19(HE LMA-3),were designed and successfully prepared through solid state reaction at 1700℃for 4 h in one step.XRD analyses show that the phase compositions of HE LMA-1,HE LMA-2 and HE LMA-3 are single-phase solid solutions with the relative density of 95.61％,95.49％and 94.31％,respectively.Heat treatment experiments demonstrate that the phase composition of HE LMA-1 remains a single phase after high-temperature heating,while second phase appears in other two samples.The stability of HE LMA-1 is attributed to small average size difference δ(～4％)of constitute elements.Intriguingly,the average emissivity of HE LMA-1 in the range of 3-6 μm reaches 0.9,which is significantly higher than that of LMA and other two HE LMA samples.The emissivity of all samples remains above 0.95 from 6 to 10 μm.In the far infrared region(10-14 μm),although the emissivity of these specimens decreases slightly,it still exceeds 0.85.The UV-Vis absorption spectra indicate that the formation of many discrete impurity energy levels with small intervals in HE LMA-1 promotes the f electrons to transit between adjacent impurity energy levels and conduction band,which enhances the infrared emission of HE LMA-1 below 6 μm.In a word,with improved phase stability and thermal emissivity in infrared range,high-entropy REMgAl11O19,especially(La0.2Nd0.2Gd0.2Sm0.2Pr0.2)MgAl11O19(HE LMA-1),is a promising candidate in thermal protection coatings of hypersonic vehicles.

Key words

High-entropy ceramics/LaMgAl11O19/Thermal stability/Infrared emissivity/UV-Vis absorption

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基金项目

National Natural Science Foun-dation of China under grant(51772027)

National Natural Science Foun-dation of China under grant(51972089)

出版年

2022
材料科学技术(英文版)
中国金属学会 中国材料研究学会 中国科学院金属研究所

材料科学技术(英文版)

CSTPCDCSCDSCI
影响因子：0.657
ISSN：1005-0302
参考文献量79
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