Reaction Behavior and Mechanism during Self-Propagating High-Temperature Synthesis Reaction in an Al-TiO₂-B₄C System

The reaction behavior and mechanism during self-propagating high-temperature synthesis (SHS) in an Al-TiO2-B4C system were investigated. The result shows that the reaction could be self-sustaining for the Al content no more than 58.4 wt pct in the reactants. With the increase in Al, the combustion temperature decreases monotonically, the ignition delay time first decreases and then increases, while the combustion wave velocity displays an opposite behavior. The reaction mechanisms are somewhat dependent on the Al content, while the resultant types of the final products are independent. The desired reaction products make the Al-TiO2-B4C system ideal for producing the (alpha-Al2O3-TiC-TiB2)/Al composites using the SHS technique.