ROLE OF ADDITIVE IN THE PHYSICO-CHEMISTRY OF GRAPHITE-BASED TRANSFER FILMS

Thin transfer films were formed on steel surfaces during friction agai nst graphite-based pins. Sodium thiosulfate Na2S2O3 or sodium molybdat e Na2MoO4 were added to graphite to improve the film formation. In ord er to understand the solid lubricant properties of the graphite + addi tive mixtures, physico-chemical characterization was performed using c lassical theta-2 theta and grazing-incidence X-ray diffraction, thermo gravimetry, Raman and micro-Raman spectroscopy and transmission electr on microscopy. The graphite + additive pins before and after friction tests and the transfer films were analysed.