Modern Powder Metallurgy (P/M) technologies are used to produce low cost high quality bearings and gears with long-term performance and reliability in critical applications (high loads and sliding velocities). One of the main advantages of P/M technology is the possibility to provide controlled porosity for selflubrication. In order to increase loading parameters of the bearings, solid lubricants like WS2 and MoS2 are usually included as additives to powders under sintering. The solid lubricants used are layered materials (e.g., platelets of 2H – MoS2). In the past few years, inorganic fullerene-like (e.g., IF) supramolecules of WS2 and MoS2 materials with structures closely related to (nested) carbon fullerenes have been synthesized. Recent experiments showed that IF possess lubricating properties superior to those of 2H platelets in a wide range of operating conditions, for example at various concentrations and load/speed ratios. However, the slippery nature of these nanoparticles leads to their fast displacement from the contact area, and consequently the efficacy of their lubrication rapidly vanishes. By confining the IF nanoparticles inside a porous and densified solid matrix, their slow release to the metal surface is expected to alleviate both friction losses and wear, while assuring the mechanical integrity of the composite. It is expected that the creation of densified powder matrix including nanoparticles of a solid lubricant with and without oil allows to develop new powder composites with largely improved mechanical properties. The results of friction and wear experiments with powdered bronze parts impregnated with commercially available 2H-WS2 particles and IF-WS2 (fullerene-like) nanoparticles were presented recently. The main issue of this work was to develop self-bearing materials impregnated with 2H and IF solid lubricants and to check their friction and wear behaviour. The effect of load on friction, wear and the transition to seizure for powdered bronze-graphite, iron-graphite and iron-nickel-graphite composites impregnated with oil, 2H and IF lubricant has been studied. It was found that the impregnation of IF into the pores allows to improve the tribological properties of the powdered composites in comparison to application of 2H-WS2 solid lubricant. The transition to seizure is determined by the adhesion of wear particles when all pores on the surface are practically closed that limits a furnishing of solid lubricant to the contact surface. The main advantages of IF is in slow release and furnishing of nanoparticles from the open pores, sliding/rolling of IF between rubbing surfaces and in limitation of the adhesion of agglomerated wear particles in the pores. The model of third body was used in order to explain the effect of wear particles, oil and solid lubricant particles on friction and wear behavior of powdered composites. It was established that the steady friction state is associated with the formation and elimination of agglomerated wear particles from the pores. The pores are filled by agglomerated and compacted wear particles during a short time. With a following loading the pores are closed and smooth surface of powdered block is covered by the adhered wear particles that leads to formation of rough surface. It is supposed that the IF nanoparticles limit the adhesion between the wear particles and the surface of pores and thus allows to preserve the equilibrium between filling and elimination of wear particles from the pores in the steady friction. The small pores filling by IF provide the support of high loads under friction of powdered IF impregnated samples. At the same time the preservation of IF nanoparticles in the contact facilitates the shear of the lubrication film and thus it improves greatly the friction properties of contact under high load.
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