Nearly stoichiometric BN fiber with high crystallinity achieved by boron trichloride assisted curing process

Abstract

Given the superior thermal stability and microwave transparency features, continuous BN fibers have displayed great potential to fulfill the increasing demand for high‐temperature structural and functional materials. The performance of BN ceramic fiber depends heavily upon its composition and microstructure. Herein, nearly stoichiometric BN fibers with high crystallinity were achieved through a facile boron trichloride (BCl3) assisted curing process. The fibers achieved a boron/nitrogen element ratio of 0.996:1 with increasing the degree of curing. After subsequent heat treatment, the fibers had uniform elemental distribution and h‐BN crystal structure. Compared with pure NH3 curing, the BN fibers cured with BCl3 demonstrated higher crystallinity (92.35%) and consistent orientation (79.8%). The existing state changes of elements revealed BCl3 assisted curing process could evenly disperse B atoms into the precursor fibers to fill the vacancies caused by nitrogen enrichment. These insights improve our understanding of preceramic fibers treatment for exploiting high‐performance BN ceramic fibers.

Pyrolysis process for boron nitride fiber derived from tris(methylamino)borane: Evolution of the molecular structure

“…If the temperature rises extremely slowly during ammonia curing, the borazine 1 will undergo polycondensation to form a high melting point polymer for curing and leave fiber with defects and low tensile strength 11 . As a result, the poor ammonia curing for PTMB has forced researchers to choose the trichloroborazine route with the more complicated process and worse spinnability, but better tensile strength after the ammonia curing to prepare BN fibers 16–19 …”

“…11 As a result, the poor ammonia curing for PTMB has forced researchers to choose the trichloroborazine route with the more complicated process and worse spinnability, but better tensile strength after the ammonia curing to prepare BN fibers. [16][17][18][19] To our best knowledge, oxygen curing is widely used in the production of carbon and silicon carbide fibers. [20][21][22] Oxygen can cure the fiber in a short time, and the resulting fiber is smooth without defects, but it has not been reported in the study of BN fibers.…”

Rheology of polyborazanes with various molecular structures and dynamic transformation process

“…[3][4][5] The fabrication of one-dimensional BN ceramic fibers, characterized by the high melting point and chemical inertness, is challenging through traditional fiber forming processes. 6,7 To overcome these challenges, the Polymer-Derived Ceramics Yiang Du and Bing Wang contributed equally to this study and should be considered co-first authors.…”

“…It has broad application prospects in electronics, aerospace, and other fields 3–5 . The fabrication of one‐dimensional BN ceramic fibers, characterized by the high melting point and chemical inertness, is challenging through traditional fiber forming processes 6,7 . To overcome these challenges, the Polymer‐Derived Ceramics (PDCs) has emerged, showcasing unique advantages.…”