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weainug

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专业: 水泥与耐火材料

[交流] 【学术文章】【原创】一篇美陶关于高温陶瓷的综述性文章

This paper reviews the crystal chemistry, synthesis, densification,
microstructure, mechanical properties, and oxidation behavior
of zirconium diboride (ZrB2) and hafnium diboride
(HfB2) ceramics. The refractory diborides exhibit partial or
complete solid solution with other transition metal diborides,
which allows compositional tailoring of properties such as thermal
expansion coefficient and hardness. Carbothermal reduction
is the typical synthesis route, but reactive processes, solution
methods, and pre-ceramic polymers can also be used. Typically,
diborides are densified by hot pressing, but recently solid state
and liquid phase sintering routes have been developed. Finegrained
ZrB2 and HfB2 have strengths of a few hundred MPa,
which can increase to over 1 GPa with the addition of SiC. Pure
diborides exhibit parabolic oxidation kinetics at temperatures
below 11001C, but B2O3 volatility leads to rapid, linear oxidation
kinetics above that temperature. The addition of silica scale
formers such as SiC or MoSi2 improves the oxidation behavior
above 11001C. Based on their unique combination of properties,
ZrB2 and HfB2 ceramics are candidates for use in the extreme
environments associated with hypersonic flight, atmospheric reentry,
and rocket propulsion.

[ Last edited by weainug on 2007-5-19 at 07:55 ]

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