|
Back to |
Processing of refractory Ti, Zr based boride/carbide/nitride ceramics by reactive hot pressing |
Intelligent choice of reaction mixtures can reduce the temperature to achieve high density TiB2 and ZrB2 based composites
TiN-TiB2 Composites
Nickel addition to a stoichiometrc 2 Ti+3BN mixture can be reactive hot pressed to ~97% dense material at 1400°C and ~99.5% density at 1600°C. In the absence of Ni, it needs temperature as high as 1850°C.
|
|
|
|
TiB2- TiN Composite without Ni produced at 1600°C |
TiB2- TiN Composite with 1%Ni produced at 1600°C |
|
TiB2- TiN composites produced under different conditions and properties Rapid reaction and densification for increased with particle contact is providing high-diffusivity path, with slight affinity of a fractional liquid phase near the Ti-rich eutectic i.e Ti-Ni
|
|
 |
XRD of the composites produced at different temperature (a) and (b) are at 1100°C, and 1200°C with 1%Ni and (c) 1100°C with 3%Ni |
|
|
|
|
SEM micrograph and EDAX analysis shows the formation of Nickel –rich phase |
|
|
|
After Ti has reacted to form TiN and TiB2 the remaining Ni is find as isolated particles. |
|
ZrB2-ZrC Composites Stoichiometric mixtures of Zr and B4C can be hot pressed to ~97% dense ZrB2-ZrC composite at 1600°C. However, small amount of excess Zr with B4C can lead to ~99% density at temperature as low as 1400°C
|
|
|
XRD of the ZrB2-ZrC composites produced at 1600°C
|
|
 |
 |
|
SEM micrograph of the stoichiometric ZrB2 –ZrC composite produced at 1600°C, dark phases are ZrB2 and light phases are ZrC |
SEM micrograph of the non stoichiometric ZrB2 –ZrCx composites produced at 1400°C dark phases are ZrB2 platelets and light phases are ZrCx. |
