@article{Wang2023, 
author = {Zhiguang Wang and Min Ge and Shouquan Yu and Xiaoming Sun and Xueli Qi and Hao Zhang and Wen Xiao and Weigang Zhang},
title = {Microstructural evolution of polymer-derived hexagonal boron nitride fibres under high-temperature stretching},
year = {2023},
journal = {Journal of Advanced Ceramics},
volume = {12},
number = {10},
pages = {1973-1988},
keywords = {polymer-derived ceramics, boron nitride fibres, microstructural evolution, high-temperature stretching},
url = {https://www.sciopen.com/article/10.26599/JAC.2023.9220801},
doi = {10.26599/JAC.2023.9220801},
abstract = {High-temperature stretching plays a crucial role in enhancing the performance of fibres, while a quantitative investigation into the impacts of tension and stretching duration on the microstructure and performance of hexagonal boron nitride (h-BN) fibres remains absent. In this study, to elucidate the microstructural evolution of the h-BN fibres under thermal stretching, amorphous BN fibres were heated at 2000 ℃ under tension of 30, 50, and 70 N for 1, 3, and 5 h in a nitrogen atmosphere. Subsequently, the grain size, pore structure, orientation degree, microscopic morphology, and mechanical properties were analysed at room temperature. The results show that high-temperature stretching enhances the orientation degree of the BN fibres, consequently elevating Young’s modulus. The maximum orientation degree of the BN fibres was 86%, aligning with a corresponding Young’s modulus of 206 GPa. Additionally, high-temperature stretching enlarged the sizes of grains and pores, a fact substantiated by the radial cracking of the fibres upon extending thermal stretching time. Owing to the expanded pore structure of the BN fibres and the inability to form a sufficiently strong "card structure" between shorter microfibre bundles, the tensile strength of the BN fibres did not increase continually, reaching a maximum of 1.0 GPa. Microstructural observations revealed that the BN fibres, composed of highly oriented lamellar h-BN grains, tend to form radial textures under high-tensile thermal stretching and onion-skin textures under prolonged thermal stretching. These findings offer a theoretical foundation for the preparation of high-performance h-BN fibres.}
}