Effect of reaction routes on the porosity and permeability of porous high entropy(Y_0.2Yb_0.2Sm_0.2Nd_0.2Eu_0.2)B₆ for transpiration cooling

Heng Chen^1,2，Zifan Zhao²，Huimin Xiang²，Fu-Zhi Dai²，Jie Zhang³，Shaogang Wang³，Jiachen Liu¹，Yanchun Zhou²

1. Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials Science and Engineering, Tianjin University2. Science and Technology on Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials & Processing Technology3. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences

摘 要：Transpiration cooling technique is a reusable and high-efficiency thermal protection system（TPS）, which is potential to improve the reusability and security of re-entry space vehicle. Relatively low density, high permeability and high porosity are general requirements for porous media of transpiration cooling systems. In this work, a new porous high entropy metal hexaboride(Y_0.2Yb_0.2Sm_0.2Nd_0.2Eu_0.2)B₆ is designed and prepared by the in-situ reaction/partial sintering method. Two reaction routes are designed to synthesize(Y_0.2Yb_0.2Sm_0.2Nd_0.2Eu_0.2)B₆, including boron thermal reduction and borocarbon thermal reduction.The as-prepared porous HE(Y_0.2Yb_0.2Sm_0.2Nd_0.2Eu_0.2)B₆ ceramics possess homogeneous microstructure and exhibit low density, high porosity, high compressive strength and high permeability. The combination of these properties makes porous HE(Y_0.2Yb_0.2Sm_0.2Nd_0.2Eu_0.2)B₆ promising as a candidate porous media for various transpiration cooling applications.

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