  In the present work the effect of surface roughness on oxidation behavior
during the early stages of high temperature exposure of Ni-base superalloy IN
625 is described. The surface roughness was described using standard contact
profilometer as well as novel method, fractal analysis. It was found that the
different surface preparation resulted in a difference in roughness with a
parameter increase of at least one order of magnitude for the ground sample as
compared with the polished sample. The oxidation test was performed in a
horizontal tube furnace. Post exposure analyses including glow discharge
optical emission spectrometry (GD OES) and scanning electron microscopy (SEM),
which revealed that grinding lowers the oxidation kinetics of IN 625. It was
found that surface preparation influences the oxide scale composition and
morphology. The hypothesis explaining the mechanism responsible for the changes
in oxidation behavior is proposed as well.
