Structural self-deterioration mechanism for zirconium diboride in an inert environment

• Published in: Ceramics international Vol. 47; no. 13; pp. 18977 - 18983
• Main Authors: Liu, Zhi-Jie, Xing, Xue-Jing, Jiang, Xian-Yu, Wang, Xin, Zhang, Li, Jian, Xian, Mu, Chun-Hong, Han, Tian-Cheng, Lu, Hai-Peng, Zhang, Lin-Bo, Yin, Liang-Jun, Deng, Long-Jiang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2021
• Subjects: A. Sintering; B. Impurities; C. Electrical conductivity; Microstructure deterioration; Microstructure deterioration; A. Sintering; B. Impurities; C. Electrical conductivity
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2021.03.241

ZrB2 is widely used in refractory linings and electrodes as well as in a range of applications including microelectronics and cutting tools, owing to its excellent characteristics, such as high hardness, high melting point, high strength, high thermal conductivity, and good thermal shock resistance. However, ZrB2 readily oxidizes, especially at high temperatures, which is ascribed to the reaction between ZrB2 and O2 in air. This study shows that a structural self-deterioration phenomenon occurs in ZrB2, even in vacuum or inert atmosphere. ZrB2 exhibits a characteristic, irreversible increase in resistivity in a high vacuum–high temperature environment. During repeated variable temperature resistivity testing, the resistivity of ZrB2 increases by 3.28% in the first cycle and 0.61% in the second. To investigate further, in-situ TEM showed that ZrB2 experiences an unusual phase transition reaction at high temperatures, even under a high vacuum environment. Oxidation results in a large number of disordered, layered structures and holes inside the ZrB2 particles. This microstructure evolution mechanism decreases the electrical conductivity and affects the performance of ZrB2. The study demonstrates the need to thoroughly investigate the microstructure changes in ZrB2 at high temperatures, under an inert atmosphere or high vacuum, and to widen the investigations to other properties beyond electrical resistivity.