Reaction between Chlorine Extreme Pressure Additives and Metal Surfaces at High Temperatures

Abstract

The high temperature corrosion of iron was investigated in hydrocarbon oils containing chlorine type EP additives, using the hot wire method1).With regard to the corrosion rate, both the parabolic law and the cubic law were observed. The former law was demonstrated by the diffusion mechanism of corrosion. The cubic law was shown by the retarding action of a barrier film which was formed on the reacting surfaces, causing the decomposition of the chlorine compounds.The complexity of the chlorine corrosion mechanism was revealed by using X-ray analysis on the formed films. The oxidation reaction and hydrolysis of formed iron chloride had to be taken into consideration in conjunction with the chlorination reaction.In the correlation between chemical reactivity and load carrying capacity of oils containing chlorine compounds, it has been found that more active oils exhibit higher load carrying capacity.Sulfur compounds were observed to yield higher Mean Hertz Load values than chlorine compounds of the same chemical reactivity. Conceivably, the solid lubricant films formed by sulfur and oxygen possess higher load carrying capacity than those formed by chlorine.