A 1.00%wt Carbon steel (FCC or \gamma?Fe) axel must operate at 850C in an oxidizing environment where the carbon content at the surface of the steel is zero. Only the outermost 200 microns of the component can fall below 0.50%wt C. (Hint: The coefficients to calculate the temperature dependence of the diffusion coefficient for carbon in steel can be found in the Callister text, if you choose not to use these values please cite your alternate source).
a) What will the concentration profile of carbon near the surface of the gear look like at the end of life of the component? (Provide a quick sketch).
b) What is the maximum time that the steel part can operate at 850C?