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Thermodynamic investigation and reaction mechanism of B 4 C synthesis based on carbothermal reduction
Author(s) -
Li Xin,
Lei Minjun,
Gao Shuaibo,
Nie Dan,
Liu Kun,
Xing Pengfei,
Yan Shu
Publication year - 2019
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/ijac.13290
Subject(s) - carbothermic reaction , materials science , ceramic , thermodynamics , atmospheric temperature range , metallurgy , physics , carbide
The reaction mechanism of B 4 C synthesis as yet remains unclear due to the lack of sufficient thermodynamic investigation, which limits the large‐scale controllable production of B 4 C ceramic material. In this paper, thermodynamic investigation of B 4 C synthesized by carbothermal reduction was calculated at atmospheric pressure over a wide temperature range (1500‐2500 K) coupled with the effects of pressure on B 4 C synthesis. Besides, predominance diagrams for B–C–O system at different temperatures and pressures were further established. Upon thermodynamic results, reaction mechanism was proposed and then verified by the synthesis experiment of B 4 C at desired temperatures. The thermodynamic investigation indicates that B 4 C may be synthesized by the reactions of C with liquid B 2 O 3 (LS mechanism) or gaseous B 2 O 2 (VS mechanism). At low temperature (~1823 K), B 4 C is polyhedral shape via LS mechanism, while two‐dimensional flake‐like B 4 C is synthesized by VS mechanism at high temperature (2123 K~). The obtained two types of B 4 C verify the accuracy of thermodynamic results. This study is instructive for the optimization of temperature, pressure for large‐scale controllable production of B 4 C ceramic material.