Thin Residual Films Between Steel-Mercury Surfaces

Abstract

Several models for adsorbed films on metal surfaces have been proposed, such as monolayers and multilayers. For these films, the effect of solvent molecule is not sufficiently taken into consideration. In this study, a steel ball and mercury surfaces were used as electrodes, and the oil-film thickness between the electrodes was estimated by measuring the capacitance of the film. n-Hexane and n-hexadecane were used as solvents. The adsorbed film is a stearic acid n-hexane solution having a concentration of less than 10 mol·m−3 showed a thickness of three molecular layers of stearic acid. On the contrary, n-hexadecane solution gave about 2 × 10−7 m of thickness. Chain-matching effects were observed with n-hexadecane solutions of acids and alcohols. The acid and alcohol having a chain-length of C16 showed the highest thickness of adsorbed Film. The difference between carboxylic and hydroxy groups was also observed in their degree of chain-matching effects. Presented as an American Society of Lubrication Engi...