Effects of TaB2 and TiB2 on the grain growth behavior and kinetics of HfB2 ceramics during pressureless sintering. Issue 5 (10th January 2020)

• Record Type: Journal Article
• Authors: Zhu, Qi‐Qi; Zhang, Zhan; Zhang, Yan; Liu, Qiu‐Yu; Song, Bang‐Chao; Guo, Wei‐Ming; Lin, Hua‐Tay
• Is Part Of: Journal of the American Ceramic Society. Volume 103:Issue 5(2020)
• Page Start: 3330
• Page End: 3337
• Publication Date: 2020-01-10
• Subjects: activation energy -- grain growth -- powders -- ultrahigh‐temperature ceramics; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.16980
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: HfB2, Hf0.95 Ta0.05 B2, and Hf0.95 Ti0.05 B2 powders were self‐synthesized and the grain sizes were 2.04, 0.36, and 1.15 μm, respectively. The three powders were pressureless sintered from 1700℃ to 2000℃ to study and compare effects of the introduction of TaB2 and TiB2 on the grain growth behavior and kinetics of HfB2 . The results revealed that HfB2 showed moderately slow grain growth in the whole process. However, significant grain growth consistently happened in Hf0.95 Ti0.05 B2 and Hf0.95 Ta0.05 B2 at 1900℃ or above. Eventually, the grain size of Hf0.95 Ti0.05 B2 increased to almost the same as HfB2, but Hf0.95 Ta0.05 B2 still possessed smaller grains due to the finest original powders. The grain growth exponent was determined to be ~3, and the dominant growth rate‐controlling mechanism was volume diffusion. The average activation energy of HfB2, Hf0.95 Ta0.05 B2, and Hf0.95 Ti0.05 B2 for grain growth at 1700℃‐2000℃ was 191 ± 34, 678 ± 73, and 321 ± 61 kJ/mol, respectively.