STUDY OF BOUNDARY FILM FORMATION WITH OVERBASED CALCIUM SULFONATE BY PM-IRRAS SPECTROSCOPY

Overbased calcium sulfonates can be used to prevent wear occurring dur ing friction phenomenon by forming a boundary film on friction surface s. The formation mechanism of the boundary film was investigated using polarization modulated infrared reflection absorption spectroscopy. I t appears that the film mainly consists of CaCO3 crystallites and that the calcium sulfonate chains are expelled from the friction zone. The expulsion of the sulfonate chains occurs in a relatively fast step an d is followed by the adsorption and the packing of calcium carbonate p articles on the surface. This adsorbed mineral phase rapidly crystalli ses into a calcite lattice with the c axis preferentially oriented per pendicular to the surface.