抄録
In order to investigate the reaction of sulphur or sulphur compounds with several metals and alloys at high temperatures, Armco iron, carbon steel and gray cast iron were at first used. The specimens were heated at various temperatures ranging from 300° to 900° in vapour of sulphur for different periods of time up to 240 hours' and the thickness of sulphide layer formed on the specimens was measured. The thickness of the sulphide increases with the rise of heating temperature and the increase of reaction period, though the rate of formation differs according to metals, i. e. Armco iron is the most rapid and gray cast iron is the most sluggish of the three used in the present experiment.
The thickness x of the sulphide layer formed is expressed by an equation, x2=kt, in which t is the reaction time and k, a constant. Between the reaction constant k and reaction temperature T°K, the following relation exists, log k=A+B/T, in which A and B are constants, that are nearly unvariable in temperatures below and above the transformation point of specimens, the boiling point of sulphur or the peritectic point, FeS+S_??_FeS2. The sulphide formed on the surface of specimen consists of two layers; the composition of these layers correspond nearly to the formula FeS, though the sulphur content is slightly less in the inner layer than in the outer. From the result above described and that of microscopic examination, a mechanism of the formation of sulphide is proposed.
