Anti-friction,anti-wear And Self-repairing Properties Of Micro/nano Lubricant Oil Additive

Natural serpentine,as a kind of environmental friendly lubricant additive,has excellent tribological properties because of its layered structure.In this thesis,the reciprocating friction and wear testing machine and four-ball friction and wear testing machine are used to investigate the friction,wear and self-repairing performance of natural serpentine powder as lubricating oil additive.Compared with the self-synthesized nano silica particles,the differences of the tribological properties and the formation of the transfer film of the powders with different Si-O bond structure were investigated:?1?The effects of different concentration,load and frequency on the tribological properties of the powder were investigated by reciprocating friction and wear testing machine.The experimental results show that compared with liquid paraffin?LP?,the micro/nano serpentine oil sample has the effect of reducing friction but the effect of anti-wear is not ideal.The average friction coefficient decreases from 0.1500 to0.1291,decreases by 13.93%,but the average wear volume increases by 102.18%.According to the analysis of wear surface,it can be seen that in the process of reciprocating friction and wear,micro/nano serpentine agglomerates and interacts with wear debris,which makes the wear mechanism change from two body wear to three body wear,leading to more serious wear.?2?Nano serpentine powders?NSPs?was prepared by further refining serpentine powders by high-energy ball milling.The tribological properties of NSPs at different concentrations and temperatures were investigated by using four-ball friction and wear testing machine,and the feasibility of using NSPs on worn surface was investigated.The experimental results shows that Compared with LP,NSPs has the best anti-friction effect when the concentration of NSPs is 0.5 wt.%.The average friction coefficient is reduced by 22.20%,and the average wear spot diameter is reduced by 34.20%.At low temperature,NSPs has better tribological properties.Compared with LP,LP+0.5 wt.%NSPs can show excellent tribological properties for a long time by using NSPs oil sample test on the worn surface.With the increase of test time,the worn surface of steel ball becomes smoother and smoother,and the average wear spot diameter remains unchanged,reaching the dynamic balance state of wear self-repairing.Through the analysis of wear surface,we can see that the excellent anti friction,anti-wear and wear self-healing mechanism of NSPs is due to the formation of a bilayer composed of graphite,iron oxide,iron organics and silicon dioxide on the wear surface under the action of tribochemistry.The formed bilayer,the first one of which contains nanoparticles surrounded by lubricants and the second one of which contains nanoparticles of Fe₂O₃,Fe₃O₄and a small amount of Si O₂that compacted onto the surface of the steel ball,is responsible for the self-repairing performance of NSPs.?3?Silica particles were prepared by St?ber method.The tribological properties of silica powder with different concentration and temperature were investigated by four ball friction and wear testing machine.The formation mechanism of the transfer film was studied by different testing time.The results show that when the concentration of silica powders is 0.1 wt.%,it has the best friction and wear resistance.Compared with LP,the average friction coefficient and the average wear spot diameter are reduced by 29.49%and 41.63%,respectively.Compared with NSPs,it has better anti-wear and anti-friction performance at the optimal concentration,and silica particles have more stable tribological performance at different temperatures.Through the analysis of wear surface in different periods of testing time,it is found that in the process of friction,silicon dioxide mainly fills in the furrow,increases the contact area,makes the friction process more stable,and plays a certain role in isolation,avoids the direct contact of friction pairs,and reduces the shear force through the ball like effect,thus reducing the friction coefficient.Different from NSPs,silica particles have excellent anti-friction and anti-wear mainly due to the physical properties of the silica particles.