Reaction Between Sulfer Compounds and Metal Surfaces at High Temperatures

Abstract

From the viewpoint that the action of EP additives is a kind of controlled corrosion, the high temperature corrosion of metals in hydrocarbon oils containing sulfur compounds was studied by using the Barcroft method.The corrosion rate of iron was observed to keep the parabolic law, and the reaction between sulfur compounds and metal surfaces could conceivably be controlled by the diffusion of reactants through the formed films on the metal wire surface. With the white oil solutions of dibenzyldisulfide, the rate of corrosion process was made to deviate from the parabolic law and the intensive corrosion was observed. The action of dibenzyldisulfide apparently depends on the characteristics with which the corrosion was associated with the cracking of surface resultant layers.It should be noted that the amount of corrosion observed in white oil alone was almost equivalent to that obtained in the case where the solution containing didodecyldisulfide or diphenyldisulfide was used. According to the data obtained by X-ray analysis of the sulfurized products, the formation of iron oxide and iron sulfide was fairly well detected. The sulfurization reaction, therefore, seems to be accompanied with oxidation reaction at high temperatures.With the corrosion of stainless steel, the corrosion rate was observed to be very slow compared to that of iron, and in the scope of this experiment, there was no promoting action during corrosion, even when dibenzyldisulfide was used.