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Nickel–Boron Nanolayer‐Coated Boron Carbide Pressureless Sintering
Author(s) -
Lu Kathy,
Zhu Xiaojing,
Nagarathnam Karthik
Publication year - 2009
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/j.1551-2916.2009.02926.x
Subject(s) - sintering , materials science , boron , compaction , metallurgy , diffusion , boron carbide , nickel , carbide , carbon fibers , chemical engineering , composite material , composite number , organic chemistry , engineering , chemistry , physics , thermodynamics
Sintering of pure B 4 C and Ni 2 B nanolayer‐coated B 4 C was studied from 1300° to 1600°C, with the holding time at the peak temperatures being 2 or 10 h. Compacts were made by uniaxial die compaction and combustion‐driven compaction. Pure B 4 C sample shows less sintering at all conditions. Ni 2 B‐coated B 4 C sample shows more extensive densification, neck formation, and grain shape accommodation. The combustion driven compaction process accelerates sintering by offering higher green density to start with. The Ni 2 B species on the B 4 C particle surfaces melts into a nickel–boron‐containing liquid phase during heating, remains as liquid during sintering, and then transforms into Ni 4 B 3 and NiB during cooling. High‐resolution composition analysis shows that there is no nickel diffusion into bulk B 4 C during the sintering process. However, there is boron diffusion into the Ni 2 B coating layer. Carbon diffusion cannot be directly measured but is believed to be a simultaneous process as boron diffusion. A multievent sintering process has been proposed to explain the observations.