ToF-SIMS analysis of friction surfaces tested with mixtures of a phosphiteand a friction modifier

The adsorption behaviour of a mixture of lubricant additives onto ferrous m aterials has been investigated by time-of-night secondary ion mass spectrom etry (ToF-SIMS). Six mixtures were made by mixing one of two types of phosp hites and one of three types of friction modifiers for subjecting to lubric ation tests. By ToF-SIMS analysis of the friction surfaces tested with thes e mixtures, the following conclusions were obtained. Adsorption of palmitic acid and glycerol monooleate was inhibited in the presence of phosphites, but the adsorption of oleyl amine was not inhibited by the phosphites. On t he other hand, the reaction of tri-n-butylphosphite was inhibited in the pr esence of oleyl amine, but for other mixed systems no inhibition of the rea ction of phosphites by a friction modifier was observed. Except for oleyl a mine mixed systems, the amount of reaction product of the phosphites was fo und to be correlated to the lubrication properties for all of the other mix ture systems. Copyright (C) 2001 John Wiley & Sons, Ltd.