Premium
Microstructure and mechanical properties of reaction‐hot‐pressed zirconium diboride based ceramics
Author(s) -
Neuman Eric W.,
Fahrenholtz William G.,
Hilmas Gregory E.
Publication year - 2019
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.13263
Subject(s) - materials science , zirconium diboride , ceramic , fracture toughness , hot pressing , composite material , microstructure , tungsten , elastic modulus , boron , metallurgy , chemistry , organic chemistry
ZrB 2 ceramics were prepared by in‐situ reaction hot pressing of ZrH 2 and B. Additions of carbon and excess boron were used to react with and remove the residual oxygen present in the starting powders. Additions of tungsten were utilized to make a ZrB 2 ‐4 mol%W ceramic, while a change in the B/C ratio was used to produce a ZrB 2 ‐10 vol% ZrC ceramic. All three compositions reached near full density. The baseline ZrB 2 and ZrB 2 –ZrC composition contained a residual oxide phase and ZrC inclusions, while the W‐doped composition contained residual carbon and a phase that contained tungsten and boron. All three compositions exhibited similar values for flexure strength (~520 MPa), Vickers hardness (~15 GPa), and elastic modulus (~500 to 540 GPa). Fracture toughness was about 2.6 MPa m 1/2 for the W‐doped ZrB 2 compared to about 3.8 MPa m ½ for the ZrB 2 and ZrB 2 –ZrC ceramics. This decrease in fracture toughness was accompanied by an observed absence of crack deflection in the W‐doped ZrB 2 compared with the other compositions. The study demonstrated that reaction‐hot‐pressing can be used to fabricate ZrB 2 based ceramics containing solid solution additives or second phases with comparable mechanical properties.