SHS SYNTHESIS OF FGM FOR THERMAL BARRIER APPLICATIONS

摘要

MB_2/AlNi (M = Ti, Zr, Hf) FGM's were prepared by Self-propagating High temperature Synthesis (SHS). Macrokinetic parameters, as combustion temperature and propagation rate, were found strongly different for the ceramic and metallic mixtures. These differences would induce high thermal gradients during the FGM synthesis leading to thermal shock damage. In order to obtain a smooth variation of the reaction parameters along the FGM samples, diluted boride mixtures were studied. The best dilutions for the FGM's synthesis were identified and applied. The ability of the prepared material as Thermal Protection System (TPS) was checked by thermal tests, evidencing as thermal insulating property increases from TiB_2 to HfB_2, through ZrB_2.