Study On The Tribological Properties Of Of Nano Copper Powders In Different Shapes

In this paper, we select stearic acid as the ball-milling process control agents, to prepare twoshapes of Surface-modified nano copper powders by the plasma-assisted ball milling device.Surface-modified nano copper powders had two shapes, the one is nano-sheets, and the other oneis nano-particles. These different shapes nano copper powders were added into40CA marinelubricating oil by certain quality score as marine lubricant additives. And then we detect thedispersion, the physical and chemical properties and the tribological performance of them.Scanning electron microscopy (SEM) is used to observe these different kinds of nano copperpowders. The result indicated that plasma assisted ball milling process can prepare the differentshapes surface modified nano-copper powders conveniently and efficiently. When the copperpowders are milled by plasma assisted ball milling process for5h, they are nano-sheets,and thethickness is about20nm. When the nano copper powder are milled by plasma assisted ballmilling process for10h, they become nano-particles, and the diameter is about20to50nm.X-ray diffraction analysis showed that the grain refinement and lattice distortion of copperpowder via plasma assisted ball milling process is greater than the ordinary ball milling process`.This will give the nano copper powders higher activity which prepared by plasma assisted ballmilling process so as to facilitate interaction in friction pair surface in the process of friction.Transmission electron microscope analysis showed that the nano copper powders which aredisposed by plasma assisted ball milling process are modified well. It is coated with stearic aciduniformly.The dispersion of different copper powders via two kinds of preparation routes in40CAmarine lubricants are tested by gravity sedimentation method and lipophilic degree’s testing. Theresults show that the nano copper sheets powders prepared by plasma assisted ball millingprocess have well dispersion for5h, the nano copper sheets powders sedimented for25days ingravity had a little precipitations, whose lipophilic degree is up to37.5%. The nano copperparticles powders prepared by plasma assisted ball milling process have the best dispersion for10h, it had little precipitations when the powders sedimented for25days in gravity, whoselipophilic degree is up to38.65%. The highest lipophilic degree of discharged and modifiedcopper powders is due to the faster adsorbtion on the copper powders surface by the plasmaactivation in plasma assisted ball-milling, which change copper powders surface from polar to non-polar.The different shapes nano copper powders were added into40CA marine lubricating oil bycertain quality score as marine lubricant additives, and then we detect the physical and chemicalproperties of them. The results show that the the physical and chemical properties conform toQ/SY RH2016-2001like viscosity and condensation point etc..The tribological performances of nano copper powders in different form prepared are testedby different operating condition. The results show that both two kinds of copper powders notonly have excellent anti-friction quality but also have wonderful self-repairing performance. Thenano copper sheets powders prepared by plasma assisted ball milling process for5h have the bestanti-friction quality and repairing performance in high loads and high rotate speed. However thenano copper particles powders prepared by plasma assisted ball milling process for10h have thebest anti-friction quality and repairing performance in specific loads and rotate speed. When theloads and rotate speed increased, the frictional coefficient is declined and the abrasion loss offriction pairs is increased. the anti-friction quality and repairing performance is depravationaccordingly.The results of SEM and energy dispersive microanalysis (EDS) on the worn surfaces showthat nano copper sheets powders and nano copper particles powders deposited in the grindingand furrows of the friction surface, and play a well role in anti-friction quality and self-repairingperformance.