Abstract:
This paper studies the estimation of titanium oxide (TiO2) thickness on a thermally oxidized nickel
titanium (NiTi) alloy based on its surface color. The NiTi plate specimens were subjected to oxidation at
temperatures from 450 °C to 900 °C for different duration to induce the formation of oxide layers of
different thicknesses. The oxide thickness of the specimens oxidized from 650 °C to 900 °C was
measured by means of scanning electron microscopy. A fitting curve was generated from the measured
thicknesses, and further extrapolated to predict the oxide thickness for specimens heated at lower
temperature of 450 °C to 600 °C. The oxide thickness estimation was done using thin-film optical
interference, with reference to the observed color of the oxidized surface. The thin-film optical
interference approach showed accurate measurement of oxide thickness as compared to the
extrapolated data, highlighting the applicability of this measurement technique. © 2022 Wiley-VCH
GmbH
