Abstract
A series of the studies on gas sulfiding for the various sintered steels have been made and some vital phenomena obtained are:
1) A suitable temperature range of the sulfiding is found to be between 300-450°C in the case of Fe-0.8%C alloys, and above this temperature, not only the quantity of iron-sulfide Fe1-xS formed in the pores begins to decrease, but also the films of iron-sulfide located on the surface of sintered steels have a tendency to peel off.
2) The quantity of iron-sulfide formed in the pores increases with lowering the density, but the sulfiding time has not large effect on the quantity.
3) The addition of copper to the sintered steels lowers each suitable temperature range of the sulfiding by 50-100°C and additionally, CuFeS2 films are observed besides the iron-sulfide Fe1-xS.
4) The depth of each sulfide layer formed in the pore of the sintered steels becomes small with decreasing H2S gas 'ratio, elevating the sulfiding temperature, increasing the density of the sintered steels and adding copper to the sintered steels.
