Large bulk solidified TiC-TiB2 eutectic composite ceramics were prepared by combustion synthesis under high gravity, and the WO3 was introduced into the combustion synthesis as one of oxidants in thermit to obtain the Ti-W-Cr-C-B liquid, so near-full-density TiB2-(Ti,W)C eutectic composite ceramics without the macrocracks were achieved. The ceramic matrix was mainly composed of TiB2-(Ti,W)C eutectic microstructures, and a few of Al2O3 and Al2O3-ZrO2 eutectic structures were also detected in between Ti-W carbides. Due to the introduction of the high gravity field, Stocks immigration of the immiscible liquids took place due to their density differences, resulting in float-up of oxide liquid and settle-down of Ti-W-Cr-C-B liquid, and the layered melt consisting of oxide liquid and Ti-W-Cr-C-B liquid was formed, finally, TiB2-(Ti,W)C eutectic composite grown from the melt. Due to the mutual solubility of W-Ti, the W atom diffused into the TiC, leading to the formation of (Ti,W)C solid solution as same as crystal lattice structure of TiC. The relative density, Vickers hardness and fracture toughness of the composite ceramics measured 98.4%, 26.4 GPa and 7.6±0.5 MPa•m1/2, respectively.
[1]
Y. Song,et al.
Microstructures and properties of large bulk solidified TiC–TiB2 composites prepared by combustion synthesis under high gravity
,
2009
.
[2]
Q. Jiang,et al.
Differential thermal analysis (DTA) on the reaction mechanism in Fe-Ti-B4C system
,
2008
.
[3]
F. Deorsola,et al.
Study of structure formation in TiC–TiB2–MexOy ceramics fabricated by SHS and densification
,
2008
.
[4]
G. S. Upadhyaya,et al.
Synthesis and sintering of TiB2 and TiB2–TiC composite under high pressure
,
2000
.
[5]
Yi-bing Cheng,et al.
Formation of TiB2–TiC composites by reactive sintering
,
1999
.
[6]
A. Ogwu,et al.
The densification and mechanical properties of a TiC and TiB2 hardmetal sintered with a reactive alloy binder
,
1996
.