Effect on Thermal Life of Low Chromium Content in BD Activated Chromium-Iron Alloys

摘要

Cr-Fe alloys were successfully produced by diffusing Cr into 1 mil 1010 steel foil stock. Uniform concentrations of Cr were provided throughout the complete foil thickness as determined by Electron Probe Analysis. After BD activation, the thermal energy and to a lesser degree the thermal life was reduced by the Cr addition. Concentrations from 0.25% Cr to 8.5% Cr were included in this study. The higher the Cr content, the lower the EPF and TPF values. Cr concentration of only 0.5% reduced the EPF value to 50% of that of the Cr-Free steel and 1% Cr and greater reduced the EPF close to O. Because of the higher negative free energy of formation of Chromium oxides over Iron oxides and because of the passive nature of Chromium, it was contemplated that small additions of Cr to steel would enhance both the thermal energy and thermal life properties. One explanation of the reverse effect by the Cr addition might be attributed to an unexpected reaction of the leached or partially leached Cr-Fe alloy with the leaching media during removal of the BD diffusion metal. One solution to the above problem might be to select another leaching media that would not react with the active Cr-Fe alloy.