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B 6 O– c ‐BN Composites Prepared by High‐Pressure Sintering
Author(s) -
Itoh Hideaki,
Yamamoto Ryuuji,
Iwahara Hiroyasu
Publication year - 2000
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.1151-2916.2000.tb01224.x
Subject(s) - sintering , fracture toughness , materials science , composite material , vickers hardness test , grain size , indentation hardness , grain boundary , flexural strength , high pressure , microstructure , engineering physics , engineering
High‐pressure sintering behavior in the B 6 O– c ‐BN system was investigated using in‐laboratory‐synthesized B 6 O and commercially available c ‐BN powders (with an average grain size of 0.5, 3, or 6 μm). No reaction occurred between the two components under the high‐pressure (4–6 GPa) and high‐temperature (1500°–1800°C) conditions that have been investigated. Well‐dispersed, sintered B 6 O– x ( c ‐BN) composites (where x = 0–60 vol%) of almost‐full density were prepared by sintering at a pressure of 6 GPa and temperature of 1800°C for 20 min. The maximum Vickers microhardness (46 GPa) of these composites was attained by adding 40 vol% c ‐BN with an average grain size of 0.5 μm. The fracture toughness of these composites increased as the c ‐BN content increased; the maximum fracture toughness (1.5–1.8 MPa . m 1/2 ) was observed for x = 40–60 vol%. Crack deflection along the B 6 O– c ‐BN grain boundary contributed to increasing the fracture toughness.