Study On The Tribological Performance Of Carbon Microspheres As Lubricant Additives

In recent years,with the rapid development of the carbon nano-materials,the new type of carbon nano lubricant additives has become the focus in the field of tribology.Among them,the carbon microspheres with its perfect spherical structure,excellent thermal stability and chemical stability have been gotten more and more attention.In this thesis,the carbon microspheres with uniform size and perfect spherical shape were prepared by a one step green hydrothermal method by using glucose as a precursor compound.The tribological performances of the carbon microspheres as lubricant additives in water,liquid paraffin and fully synthetic engine oil were evaluated.The effect of different metal material on lubrication performance of carbon microspheres was also probed.The experiments are in progress with certain results.(1)There are many oxygen containing functional groups on carbon microspheres by the methods of infrared spectrum analysis.Its tribological properties of carbon microspheres as a lubricant additive in water-based lubricant were evaluated on steel-steel pairs.At the same time,the mixed water lubricants composed of both carbon microspheres and nonionic surfactant,Tween-80,possessed excellent friction-reducing and antiwear performance.(2)Carbon microspheres were also applied to oil lubrication.The mixed liquid paraffin lubricants composed of carbon microspheres and nonionic surfactant,Span-80,possessed excellent anti-friction and wear-resistance performance.(3)The results indicate that the carbon microspheres possess good anti-friction and wear-resistance performance when they are used as a lubricant additive in liquid paraffin contained Span-80 on aluminum alloy substrate with larger surface roughness.At the same time,the carbon microspheres could not been applied to the titanium alloy substrate with the smaller surface roughness.(4)The coefficient of friction could not be effectively reduced when the 0W-40 fully synthetic engine oil lubricant containing carbon microspheres are used to lubricate the steel/stainless steel,steel/titanium alloy or steel/aluminum alloy pairs.However,the wear could be greatly reduced after addition of carbon microspheres in the engine oil.(5)The lubricating mechanism of the carbon microspheres are suggested as follows.Carbon microspheres are involved in the sliding contact area with help of surface deposition and surface roughness.At the same time,carbon microspheres are accumulated and extruded constantly at the entrance of contact region,making it easier to enter the friction area to participate in lubrication.There is a physical separation between the contact interface,and the sliding friction is translated into the rolling friction to a certain degree.Therefore friction and wear are reduced.In general,the carbon microspheres prepared by a simple hydrothermal method are recognized as a potential lubricant additive.