Materials Science

9 A sheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200°C and is permitted to achieve a steady-state diffusion con- dition. The diffusion coefficient for nitrogen in steel at this temperature is 6 × 10−11 m2/s, and the diffusion flux is found to be 1.2 × 10−7 kg/m2s. Also, it is known that the concentration of nitrogen
3 in the steel at the high-pressure surface is 4 kg/m .
How far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3? Assume a lin- ear concentration profile.