Effects of Boron Source on Combustion Synthesis of Chromium Boride/Al₂O₃ Composites

Abstract

Chromium boride/Al₂O₃ composites were synthesized by incorporating the thermite reaction into a self-propagating combustion process. Boride phases formed from the Cr₂O₃ + 2Al + xB samples were identified as Cr₂B, CrB, and CrB₂ with respect to their starting stoichiometries of x = 1.2, 3.0, and 7.0, indicative of the need of excess boron. On the other hand, Cr₂B, CrB, and CrB₂ were yielded from the Cr₂O₃ + 2Al + yB₄C reactant compacts containing B₄C of y = 0.25, 0.5, and 1.0, respectively. This shows that B₄C as the boron source resolves the problem of boron loss during combustion synthesis.

Keywords:

• Alumina
• Boride
• Boron
• Ceramics
• Combustion
• Composites
• Synthesis
• X-ray

ACKNOWLEDGMENT

Authors are grateful for the Precision Instrument Support Center of Feng Chia University in providing the measurement facilities.