Densification of Hot-Pressed HfB2 Ceramics with Carbon and B4C Additions
Densification of Hot-Pressed HfB₂Ceramics with Carbon and B₄C Additions
Hafnium diboride was densified below 2000°C using B4C and carbon additions. Attrition milled HfB2 containing no sintering additives was hot pressed to >99% relative density at temperatures 2000°C. Intergranular porosity was evident in additive free HfB2 microstructures despite the high relative density. Addition of 2.65 wt.% carbon to attrition milled HfB2 powder resulted in >98.5% dense billets after hot pressing at 1850°C. Densification plots revealed that the addition of 4 wt.% B4C or carbon resulted in rapid early densification at lower temperatures than those observed for additive free HfB2. Densification of 2.65%C:HfB2 and 4%B4C:HfB2 began below 1700°C and 1750°C, respectively, whereas densification began around 1850°C for additive free HfB2. Carbon containing HfB2 densification became rapid at 1800°C. The enhanced densification was attributed to removal of oxide impurities at the HfB2 particle surfaces by reaction with B4C and carbon additions. Further, addition of carbon enhanced the densification of HfB2 more effectively than B4C.
H. J. Brown-Shaklee et al., "Densification of Hot-Pressed HfB2 Ceramics with Carbon and B4C Additions," Proceedings of the 10th International Conference, Goller Verlag, Jan 2007.
Materials Science and Engineering
National Science Foundation (U.S.)
Keywords and Phrases
Hafnium Diboride; UHTC; Hot Pressing; Sintering Aids
Article - Conference proceedings
© 2007 Goller Verlag, All rights reserved.
01 Jan 2007