The Influence of the Spatial Organization of Carbon Nanostructures on Antiwear Characteristics of Model Lubricating Systems under a Hard Friction Mode

The following carbon nanostructures (CNSs) are used: shungite nanocarbon (Sh), multilayered graphene oxide (GO), multiwalled carbon nanotubes (Taunit-M), and fullerene C60. Medical Vaseline (MV) free from any additives or thickeners is used as a lubricant base. Tribological tests are carried out using a 2070 SMT-1 friction machine at a load of 2000 N. The roughness parameters of steel rollers before and after the tests are studied by profilometry. Detailed characteristics of contacting surfaces before and after friction are obtained by scanning and transmission electron microscopy. The experimental data are analyzed using the Hertz and Johnson–Kendall–Roberts models. According to the data on efficiency coefficients k_ef, the studied dispersions are ranked as follows in the order of deterioration of antiwear properties: MV/GO (0.5 wt %), k_ef of 50% > MV/Taunit-M (1.5 wt %), k_ef of 40% > MV/C60 (0.5 wt %), k_ef of 15% > MV/Sh (0.5 wt %), k_ef of 5%, which is in agreement with the above-mentioned sequence of CNSs at low loads. The reason for the best and worst wear factors upon using CNSs in the dispersions under study and factors affecting the values of wear in the hard friction mode are considered. The results of the study can be a basis for the development of new plastic lubricating compositions with carbon nanostructure additives for use in heavily loaded friction units.