Modification And Study Of Nano-Y₂O₃ As Lubricant Additive

Nano rare earth particles have quantum size effect and surface effect, and nano rare earth additive add into the lubricating oil can significantly improve the lubrication properties and carrying capacity of lubricanting oil,and it have the superiority that traditional lubricant additives can not analogy,nano rare earth material has the characteristic attributes of both nanometer material and rare earth material, but nano rare earth material has strong hydrophilic,it can not stable dispersion in the based lubricant oil. And surface modification to the nano rare earth material was necessary. The main work of the article was modification and study of the nano-Y2O3 as lubricant additive,the research contents and conclusion as follow:(1) Nano-Y2O3 was prepared by the precipitation method, the preparation condition as follow:the Y3+ concentration was 0.35mol/L, dispersant dosage was 12g/L, n(NH4HCO3): n(Y3+)=4:1,reaction temperature was 90℃,stirring speed was 400r/min, drying temperature of precursor was 80℃,drying temperature was 80℃,drying time was 13h, roasting temperature of precursor was 850℃, roasting time 2h.And result show that the structure of nano-Y2O3 prepared by this experiment was cubic system; fluorite structure of CaF2; round-likely roundness particles,particles has similar size and shape, the average size of nano-Y2O3 particles was 25.0nm.(2) The surface of nano-Y2O3 was modified by the stearic acid and the process of esterification modified to nano-Y2O3 as follow:the ratio of nano-Y2O3 and modification agent was 10:2,modification time was 120min,pH was 6.0, and then the lipophilic degree of modified nano-Y2O3 was 70.59%.Result show that stearic acid modification does not affect the crystal structure of nano-Y2O3, and it was still round-likely roundness,stearic acid linked on the surface of nano-YaO3 by chemical bond, the surface of nano-Y2O3 coated by a layer of stearic acid and coating amount was 12.17%.(3) The surface of nano-Y2O3 modified by silane coupling agent(A-171) and then the coupling modification nano-Y2O3 was modified by the method of grafted and it was realized that the coupling modification nano-Y2O3 coated by methacrylate.The process of coupling modification as follow:reaction temperature was 70℃, the ratio of coupling agent was 10:4, reaction time was 4h,the dosage of acetic was 0.2 mL/g(Y2O3); the grafted process as follow: reaction temperature was 75℃,the dosage of initiator was 1.3%,modification time was 3h,the dosage of monomer was 1:12. Result show that crystal form of nano-Y2O3 was not affected by modification methods, a layer of coupling agent coated on the surface of nano-Y2O3 by coupling modification and coating amount was 12.17%; a layer of methacrylate coated on the surface of nano-Y2O3 by grafting modification and coating amount was 22.2%.(5) As the lubricant additive, lubrication performance of modification nano-Y2O3 was determined by the four-ball tester. Before the determination, modification nano-Y2O3 will add into liquid paraffin,the determination result show that the performance of lubricanting oil improved greatly by add into modification nano-Y2O3, the maximum of extreme pressure properties(PB) was more than 500N; the maximum of sintering load (PD) was to 1569N;compare with the liquid paraffin, the wear scar diameter was decreased more than 21%,and the modified nano-Y2O3 have predominant dispersion stability. Comparison and analysis show that the friction and wear properties of stearic acid modified nano-Y2O3 was superior to the grafting modified nano-Y2O3, proved that stearic acid modified nano-Y2O3 have better lubrication performance.