Nanodiamond-based oil lubricants on steel-steel and stainless steel – hard alloy high load contact: investigation of friction surfaces

In the current paper, synergistic compositions of detonation nanodiamond (DND) particles in the form of aggregates and fully deagglomerated 5nm particles were used as additives to 10W40 and 5W30 oils, correspondingly. Ringondisk and blockonring tribological tests were performed under high load conditions (300N and 980N) using friction pairs with different relative hardness. Significant reduction of wear was observed for the HRC25/25, HRC25/50 and HRC30/HRC60 steel/steel friction pairs, while for the HRC60/60 steel/steel and HRA86/HRC24 hard alloy/steel friction pairs increased wear took place. It was concluded that use of ND in lubricants under high load conditions should be approached cautiously taking into account absolute and relative hardnesses of the friction surfaces.