氧化石墨烯作为润滑油添加剂的分散稳定性

Dispersion Stability of Graphene Oxide as Lubricant Additive

本工作在实验室自主设计的超声辅助球磨、微波辅助球磨试验装置基础上,采用不同的分散方法(表面改性分散,分散剂分散,表面改性、分散剂分散)将氧化石墨烯(GO)分散于基础油PAO6中得到GO润滑油。采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)仪等对改性前后的GO进行表征,通过紫外可见分光光度计(UV-Vis)和Zeta电位仪检测分散稳定性,并对其分散机理进行讨论。研究结果表明,GO经表面改性、分散剂分散复合处理后,其稳定性比表面改性分散和分散剂分散分别提高了44.8%和35.5%。GO经表面改性后,表面含氧官能团减少,润湿性得到提高,表面接枝亲油性长碳链烷基伸入到基础油中,提高了GO的分散稳定性。分散剂吸附在改性氧化石墨烯(MGO)表面,形成稳定的双电层效应,纳米MGO颗粒产生静电排斥作用,形成位阻层,阻碍颗粒的相互碰撞和团聚,从而能稳定分散于基础润滑油中。本工作不仅成功将GO稳定分散于基础油PAO6中,而且验证了表面改性、分散剂分散复合处理对提高GO在基础油中的分散稳定性效果最好,且分散剂的最佳浓度为0.6%。

The work was based on te laboratory-designed ultrasound-assisted ball milling and microwave-assisted ball milling test equipment,the GO lubricant oil was obtained by dispersing the GO in the base oil PAO6 using different dispersion methods(surface modification and dispersion,dispersant dispersion,surface modification and dispersant dispersion).Examinations of the surface features of the GO were conducted by XRD,SEM,TEM etc.before and after modification.The dispersion stability of the GO in the base oil was measured by ultraviolet-visible spectrophotometer(UV-Vis)and Zeta potential,and the dispersion mechanism was analyzed.The results indicated that,compared with surface modification dispersion and dispersant dispersion,the combination of surface modification and dispersant dispersion improved the stability of the GO by 44.8%and 35.5%,respectively.After surface modification of GO,the oxygen-containing functional groups on the surface were reduced,the wettability was improved,and the surface was grafted with a lipophilic long-chain alkyl group,which penetrated into the base oil to improve the dispersion stability of the GO.The dispersant was adsorbed on the surface of the modified graphene oxide(MGO)to form a stable double-layer effect.The nano-MGO particles could generate electrostatic repulsion and form a steric hindrance layer to prevented the particles from colliding with each other and agglomerates which could help the MGO disperse in the basic lubrication oil stably.The work not only dispersed the GO in the base oil PAO6 successfully,but also concluded that the combination of surface modification and dispersant dispersion had the best effect on improving the dispersion stability of GO in the base oil,and the optimal concentration of the dispersant was 0.6%.