Gears are to be subjected to the process of gas carburizing in which ch4 disassociates at the metal surface and the c diffuses into the steel forming a thin carbon-rich layer which can then be hardened by appropriate heat treatment. the gears are of steel, originally containing 0.17% c. the diffusion coefficient (do) for carbon in austenite is 0.21 sq cm/sed and the activation energy is33.8 kcal/mole. the process is maintained at a temperature of 975°c.. if the surface of the metal is maintained at a carbon content of 1.1 per cent, what will be the time required to increase the carbon content 0.5 mm below the surface to 0.5 per cent? what will be the carbon content 1.5 mm below the surface at that time?