A novel microstructural design to improve the oxidation resistance of ZrB2-SiC ultra-high temperature ceramics (UHTCs)

JOURNAL OF ALLOYS AND COMPOUNDS

卷:785

Article

Zhang, Haiwen¹  Jayaseelan, D. D.²  Bogomol, I³  Reece, M. J.⁴  Hu, Chunfeng¹  Grasso, S.¹  Lee, W. E.⁵ 

[1] Southwest Jiaotong Univ, Sch Mat Sci & Engn, Key Lab Adv Technol Mat, Minist Educ, Chengdu 610031, Sichuan, Peoples R China

[2] Kingston Univ London, Dept Aircraft & Aerosp Engn, London SW15 3DW, England

[3] Natl Tech Univ Ukraine KPI, Peremogy Av 37, UA-03056 Kiev, Ukraine

[4] Queen Mary Univ London, London, England

[5] Imperial Coll London, Ctr Adv Struct Ceram, Dept Mat, London SW7 2AZ, England

关键词: Eutectic structure;    ZrB2-SiC;    Microstructure;    Oxidation;   

DOI  :  10.1016/j.jallcom.2019.01.208

来源: Elsevier

【 摘 要 】

Directionally Solidified 72.8 mol% ZrB2 - 27.2 mol% SiC (equivalent to 20 vol%) composite was fabricated using a crucibleless-melting technique. Microstructural and XRD analyses confirmed the texturing of grains and lamellar structure. The Lotgering (001) orientation factor was as high as 0.97. The thickness of the lamellae was about 5 mu m. Bright-field TEM images confirmed that the eutectic composite has continuous ZrB2 and SiC phases. Electron diffraction patterns from both the ZrB2 and SiC phases were indexed as hexagonal and 3C-cubic structures, respectively. Line defects such as dislocations, planar defects such as stacking faults and twins were observed in the SiC. Oxidation studies performed at 1873K for 1 h demonstrated that the samples obtained by melting showed an improved oxidation resistance compared to ZrB2-SiC composites obtained via sintering due to the formation of a passivating continuous SiO2 layer. The oxidation mechanisms are discussed, the orientation and SiC lamellae acted as an effective barrier to the inward oxygen flux and played a key role in retarding oxidation. Crown Copyright (C) 2019 Published by Elsevier B.V. All rights reserved.

【 授权许可】

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