A sheet of BCC iron 1 mm thick was exposed to a Carburizing atmosphere on one side and decarburizing on the other at 725 C. After having reached steady state, the iron was cooled quickly to room temperature. The carbon concentrations on the surfaces were determined: 0.012 and 0.0075 wt%. Compute the diffusion coefficient if the flux is 1.4 10^(-8 kg)/m^21-s.