%0 journal article
%@ 0010-938X
%A Solimani, A., Schuetze, M., Stark, A., Galetz, M.C.

%D 2018
%J Corrosion Science

%P 180-190 
%R doi:10.1016/j.corsci.2018.10.007
%T Nitrogen transport through thermally grown chromia scales
%U https://doi.org/10.1016/j.corsci.2018.10.007
 
%X Nitrogen transport through the chromia scale formed on chromium in N2-O2 atmospheres is studied. In-situ high-energy synchrotron X-ray diffraction (HEXRD) and two-stage thermal analysis results indicated that a scale, free of physical defects, protects the substrate from nitridation. The oxygen activity (pO2) in the nitrogen containing atmosphere played a significant role in scaling kinetics, physical defect formation, and nitrogen transport behavior. Low pO2 atmospheres (pO2 ≈ 10−6 atm) provided slower scaling kinetics, fewer physical defects, and a barrier character against nitrogen transport compared to the high pO2 atmospheres such as air. Two molecular nitrogen transport mechanisms based on “wrinkling” and “micro-cracking-healing” are proposed and discussed.