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Processing and properties of polycrystalline cubic boron nitride reinforced by SiC whiskers
Author(s) -
Li Jian,
Shao Gang,
Ma Yao,
Zhao Xiaotong,
Wang Hailong,
Zhang Rui
Publication year - 2018
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.13077
Subject(s) - materials science , flexural strength , fracture toughness , composite material , sintering , boron nitride , relative density , vickers hardness test , scanning electron microscope , microstructure , silicon carbide , boron carbide , whisker , crystallite , whiskers , metallurgy
Dense polycrystalline cBN (Pc BN )–SiCw composites were fabricated by a two‐step method: First, SiO 2 was coated on the surface of cubic boron nitride ( cBN ) particles by the sol‐gel method. Then, silicon carbide whisker (SiC w )‐ coated cBN powder was prepared by carbon thermal reaction between SiO 2 and carbon powders at 1500°C for 2 hour. Then, cBN –SiC w complex powders were sintered by high‐pressure and high‐temperature sintering technology using Al, B, and C as sintering additives. The phase compositions and microstructures of cBN –SiC w composites were investigated by X‐ray diffraction and scanning electron microscopy, respectively. It was found that the SiC w and Al 3 BC 3 had been fabricated by in situ reaction, which cannot only promote densification but also improve mechanical properties. The relative density of Pc BN composites increased from 96.3% to 99.4% with increasing SiC w contents from 5 to 20 wt%. Meanwhile, the Vickers hardness, fracture toughness and flexural strength of as‐obtained composites exhibited a similar trend as that of relative density. The composite contained 20 wt% of SiC w exhibited the highest Vickers hardness and fracture toughness of 42.7 ± 1.9 GPa and 6.52 ± 0.21 MPa•m 1/2 , respectively. At the same time, the flexural strength reached 406 ± 21 MPa.