Material processing and surface reaction studies in free piston driven shock tube

Summary

Recently established moderate size free piston driven hypersonic shock tunnel HST3 along with its calibration is described here. The extreme thermodynamic conditions prevalent behind the reflected shock wave have been utilized to study the catalytic and non-catalytic reactions of shock heated test gases like Ar, N₂ or O₂ with different material like C₆₀ carbon, zirconia and ceria substituted zirconia. The exposed test samples are investigated using different experimental methods. These studies show the formation of carbon nitride due to the non-catalytic interaction of shock heated nitrogen gas with C₆₀ carbon film. On the other hand, the ZrO₂ undergoes only phase transformation from cubic to monoclinic structure and Ce_0.5Zr_0.5O₂ in fluorite cubic phase changes to pyrochlore (Ce₂Zr₂O_7±δ) phase by releasing oxygen from the lattice due to heterogeneous catalytic surface reaction.