Abstract
Experiments on the sulphurization of cast iron in H2S gas current at high temperatures were conducted and the following results were obtained.
(1) The sulphurization product of cast iron was composed of pyrrhotite Fe1-xS and pyrite FeS2, which were the same as those of iron and steel. In the outer layer of sulphurization product, carbon and phosphor didn't diffuse, on the contrary manganese diffused freely, silicon did a little.
(2) The sulphurization rate was controlled by the parabolic rate law, and the following formula was obtained:
W2=1.15×10-6t
W: sulphurization rate, g/cm2
t: sulphurization time's
(3) Between the sulphurization rate and temperature, the exponential law was found and the following formula was obtained.
K=10-2·e-33500/RT
K: sulphurization rate constant, (g/cm2) 2/s
R: gas constant
T: sulphurization temperature, °K
(4) The structure of cast iron did not affect the sulphurization rate.
(5) Carbon expedited the sulphurization rate of cast iron, on the contrary silicon and manganese did not expedite it.
