Coordinated test-rig and ToF-SIMS experiments to investigate the influence of phosphate glass layers on the friction behavior of a wet clutch

The structure and chemical composition of boundary layers built under tribological stress impact the friction and wear of solid-state surfaces in a major way. Time-of-flight secondary ion mass spectrometry is ideally suited for the analysis of these boundary layers, including the adsorptive layer formed from oil additive components, and to advance the understanding of the interaction of all materials involved. Tribologically formed phosphate glass layers on friction body surfaces of standard wet multi-disc clutches, which had been exposed to defined loads in an environment of different model fluids of polyalphaolefin base oil blended with different single additives or well-defined mixtures of two additives, were investigated using time-of-flight secondary ion mass spectrometry. The obtained data give an insight on how additive-based reaction layers on friction surfaces may affect the friction curve of a wet clutch.