Chemical modification of the friction surfaces and its evaluation based on the carryover effect measurements

A carryover effect, demonstrating a prolonged action of tribologically active additives in lubricating oils on the friction surfaces, was considered to be a result of surface chemical modifications. A new approach to carryover effect detection was suggested, and a method for its quantitative evaluation using a four-ball tribometer was described. The carryover effect was measured for a series of tribologically active additives to lubricating oils at various test conditions. The carryover effect was shown to increase when higher axial loads and increased additive concentrations were used. A comparison of carryover effect values with critical loads (Pcr) for the studied additives allowed us to estimate the strength of protecting films being formed on the friction surfaces and the rate of their regeneration.