The surface of an iron component is to be hardened by carbon. The diffusion coefficient of carbon in iron at 1000°C is given to be 3 × 10?11 m2/s. If the penetration depth of carbon in iron is desired to be 1.0 mm, the hardening process must take at least

Question

(a) 1.10 h
(b) 1.47 h
(c) 1.86 h
(d) 2.50 h
(e) 2.95 h

Answer 1

(e) 2.95 h
D_AB=3E-11 [m^2/s]
delta_diff=1E-3 [m]
delta_diff=sqrt(pi*D_AB*t)
t_hour=t*Convert(s, h)