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Hot Pressed HfB 2 and HfB 2 –20 vol%SiC Ceramics Based on HfB 2 Powder Synthesized by Borothermal Reduction of HfO 2 *
Author(s) -
Ni DeWei,
Zhang GuoJun,
Kan YanMei,
Wang PeiLing
Publication year - 2010
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/j.1744-7402.2009.02404.x
Subject(s) - materials science , equiaxed crystals , fracture toughness , hafnium , flexural strength , relative density , composite number , ceramic , sintering , particle size , amorphous solid , composite material , metallurgy , analytical chemistry (journal) , chemical engineering , microstructure , zirconium , crystallography , chromatography , engineering , chemistry
Phase pure hafnium diboride (HfB 2 ) powder was synthesized by borothermal reduction of hafnium dioxide using amorphous boron at relatively low temperature (1600°C) in vacuum. The synthesized HfB 2 powder had an average particle size of 1.37 μm with an equiaxed shape, and a low oxygen content of 0.79 wt%. Using the as‐synthesized HfB 2 powder and a commercial SiC, HfB 2 monolithic, and HfB 2 –20 vol%SiC composite were hot pressed at 2000°C to relative densities of 95.7% and 99.2%, respectively. With the addition of SiC, the grain size decreased and the fracture behavior changed from intergranular to a mixed mode, which resulted in a high flexural strength of 993±90 MPa for the composite. Fracture toughness of the composite was 6.29±0.65 MPa m 1/2 , which was significantly higher than that of the HfB 2 monolithic and the reported values in literature.