Width Temperate Preparation And Tribological Behavior Of Self-lubricating Nickel-based Materials Research

With rapid development of modern aeronautic industry, novel materials and solid lubricants which have excellent tribological properties over a wide temperature range are urgently needed to be researched. In this article, Ni-based alloy with graphite and M0S2 or their mixture were prepared using powder metallurgy (PM) method. Their microstructure and organization were analyzed by XRD and SEM and tribological properties were tested by MG2000 high temperature tribometer. The effects of lubricant contents, alloyed elements, temperature, load, velocity and Laser surface texturing (LST) on tribological properties were investigated. At last, wear and lubrication mechanisms were discussed.With the addition of graphite and M0S2, tribological properties at high temperature were improved while poor mechanical properties were obtained because of sulfide and carbide formation in the matrix. Aluminum and titanium addition was favored to the mechanical properties improvement. Hardness was increased from HB202 to HB500 while anti-bending strength was improved 10% after adding alloy element. The optimum graphite content was 9wt%～12wt% and for molybdenum disulfide it was 6wt%—12wt%. From room temperature to 600 ℃, friction coefficient of composite with 9wt% graphite was 0.22—0.46, which was 50 percent lower than that of composite without graphite, while wear rate was 2.5～5.8×10^-14m³/ (N·m) , which was one grade of magnitude lower. Composite with 12wt% M0S2 showed optimum combination of mechanical and tribological properties, especially at high temperature and heavy load. Its friction coefficient was 0.2～0.3 from room temperature to 600℃, while wear rate was at the magnitude of 10^-4m³·N^-1·m^-1. The lowest friction coefficient and wear rate were obtained when adding both graphite and M0S2 to Ni-based alloy. While rubbing against silicon nitride, its friction coefficient was lower than 0.3 and wear rate was at the range of 1.0～ 3.5×l0¹⁵m³/ (N·m) . After laser surface textured and filled with molybdenum disulfides powder, steady friction coefficient of Ni-based alloy was lower than 0.1 while oil lubrication was 0.02～0.05. It was found that friction coefficient was reduced because of pores storing solid lubricants and trapping wear debris.At low temperature, graphite or sulfide functioned to relieve friction, while the film consisting of sulfide and naturally occurring oxide played an important role of lubricating at high temperature. Abrasive was the dominant wear mechanism at high temperature.