High-temperature oxidation kinetics of NiAl single crystal and oxide spallation as a function of crystallographic orientation

摘要

Isothermal and cyclic high-temperature oxidation of NiAl single crystal samples are presented. Oxidations have been carried out at 900, 1050,1100 and 1150℃ on (100) and (110) oriented surface. Continuous thermogravimetry in cyclic conditions allows isothermal oxidation kinetics and spalling at each cycle to be followed. Oxidation kinetics are compared between (100) surface and (110) surface. (100) oriented surfaces appeared to oxidize slightly faster than (110) oriented surfaces. Experimental results of cyclic oxidation are compared to simulated results using a previously published statistical model. Spalling increases when the average oxide scale thickness increases with the number of cycles. Longer tests are necessary to study this evolution during the 'steady-state' but no critical oxide thickness was found.