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New insight into the formation and oxygen barrier mechanism of carbonaceous oxide interlayer in a multicomponent carbide
Author(s) -
Ye Ziming,
Zeng Yi,
Xiong Xiang,
Qian Tianxiao,
Lun Huilin,
Wang Yalei,
Sun Wei,
Chen Zhaoke,
Zhang Lijun,
Xiao Ping
Publication year - 2020
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17143
Subject(s) - oxidizing agent , oxide , oxygen , carbide , diffusion barrier , materials science , carbon fibers , grain boundary , chemical engineering , diffusion , metal , layer (electronics) , barrier layer , inorganic chemistry , nanotechnology , metallurgy , chemistry , composite material , microstructure , organic chemistry , composite number , physics , engineering , thermodynamics
Early transition metal carbides are considered to be superior candidate materials for oxidizing environments at temperatures exceeding 2000°C. Generally, the remarkable oxidation resistance is largely attributed to a carbonaceous oxide interlayer (eg, Hf–O–C, Zr–O–C, and Ta–O–C), located at the interface between the external oxide layer and internal carbide (eg, HfC, ZrC, and TaC), acting as the primary oxygen barrier. However, the oxygen barrier mechanism of the carbonaceous oxide interlayer remains unclear. Herein, through studying the oxidation behavior of a novel multicomponent carbide Hf 0.5 Zr 0.3 Ti 0.2 C in oxidizing environments up to 2500°C, the oxygen barrier mechanism of the carbonaceous oxide was recently revealed. We found that the oxygen barrier resulted from the slow oxygen diffusion through the inner grains of Hf‐Zr–Ti–O due to the presence of carbon formed at the grain boundaries because of the existence of compact external oxide layer, beneath which the Hf–Zr–Ti–O–C interlayer possesses much lower oxygen activity and temperature that allow carbon to exist stably. This as‐formed carbon strongly retarded the fast diffusion of oxygen along the grain boundaries of oxides. Additionally, desirable synergisms of the designed multicomponent system, particularly, the outward short‐circuit diffusion of Ti, lead to the self‐healing of the external oxide layer, evidently enhancing integral protection performance against oxidizing environments.