Adsorption of Model Compounds of Lubricant on Nascent Surfaces of Mild and Stainless Steels under Dynamic Conditions

Abstract

Mild steel and stainless steel specimens were activated mechanically by cutting under high vacuum at room temperature, and sub-monolayer levels were adsorbed. It was found that the compounds could be divided into two groups according to their adsorption activity on the cut surface. Benzene, 1-hexene, methyl proprionate and diethyl disulfide exhibited a high adsorption activity, while the polar compounds propionic acid, propylamine, trimethyl phosphate and trimethyl phosphite exhibited comparatively low activity. The functional groups of the former compounds have a higher polarizability than that of the latter compounds. The results are discussed on the basis of the Pearson's HSAB (Hard and Soft Acids and Bases) principle. It was found that the nascent surface was so active that benzene decomposition and the reaction of diethyl disulfide with the surface occurred even at room temperature.