Journal of Inorganic Materials, Volume. 40, Issue 7, 817(2025)

ZrB2-HfSi2 Ceramics: Microstructure and Formation Mechanism of Core-rim Structure

Zhifan WEI, Guoqing CHEN*, Yufei ZU, Yuan LIU, Minghao LI, Xuesong FU, and Wenlong ZHOU
Author Affiliations
  • School of Materials Science and Engineering, Dalian University of Technology, Dalian 116085, China
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    In recent years, ZrB2, as a representative material of ultra-high temperature ceramics (UHTCs), has become an important candidate material system for components of new generation aerospace vehicles. However, its practical application is limited by difficulties in material preparation and processing of complex components. This study aims to optimize sintering process of ZrB2-based UHTCs by introducing HfSi2 as a sintering aid, specifically addressing the challenge of densification caused by low intrinsic diffusion coefficient of traditional ZrB2 ceramics. The research focuses on elucidating formation mechanism of core-rim structured borides and their role in enhancing densification of ZrB2-HfSi2 ceramics. Dense ZrB2-HfSi2 ceramics were successfully fabricated via hot-press sintering at 1600 ℃. The results reveal that softening of HfSi2 phase during sintering effectively fills interparticle gaps, thereby facilitating low-temperature densification. Furthermore, during the holding stage, interdiffusion of Hf and Zr atoms through a dissolution-reprecipitation mechanism facilitates formation of a core-rim structured ZrB2/(Zr,Hf)B2 composite. This core-rim structure consists of ZrB2 core encased by a (Zr,Hf)B2 rim, characterized by a fully coherent interface (hexagonal P6/mmm symmetry) with a low lattice mismatch (<5%), ensuring interfacial stability. The ZrB2-HfSi2 ceramic exhibits a compressive strength of (1333±83) MPa, a Vickers hardness of (15.86±0.72) GPa, and a fracture toughness of (2.01±0.36) MPa·m1/2. The ZrB2-HfSi2 ceramic demonstrates typical intergranular fracture behavior, with only a limited number of cleavage planes displaying core-rim structural features. These findings provide critical insights into low-temperature sintering of UHTCs and underscore potential of core-rim structures in advancing the preparation of high-performance ceramics.

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    Zhifan WEI, Guoqing CHEN, Yufei ZU, Yuan LIU, Minghao LI, Xuesong FU, Wenlong ZHOU. ZrB2-HfSi2 Ceramics: Microstructure and Formation Mechanism of Core-rim Structure [J]. Journal of Inorganic Materials, 2025, 40(7): 817

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    Paper Information

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    Received: Feb. 17, 2025

    Accepted: --

    Published Online: Sep. 3, 2025

    The Author Email: Guoqing CHEN (gqchen@dlut.edu.cn)

    DOI:10.15541/jim20250060

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