硫醚键桥接的共价有机纳米添加剂的制备及其摩擦学性能研究

Preparation of covalent organic nano-additive bridged by sulfur ether bonds and investigation of its tribological properties

目的合成含有高活性硫元素的共价有机骨架纳米材料,将其作为润滑油添加剂加入到基础油聚α-烯烃(PAO 10)中,研究其在钢/钢摩擦副上的减摩、抗磨性能,揭示可能存在的润滑机理。方法以三聚硫氰酸和三聚氯氰为原料,采用溶剂热法在不同温度下合成硫醚键桥接的三嗪基共价有机骨架纳米材料(简称S-COFs-T,T=80,120,160),并利用X射线粉末衍射仪、X射线光电子能谱仪、同步热分析仪、扫描电子显微镜、微振动摩擦磨损试验机和三维光学轮廓仪对所合成的纳米材料进行理化性能和摩擦学性能表征。结果S-COFs-T纳米材料随着合成温度的升高,结晶度逐渐增强,同时尺寸逐渐变小且具有层状结构;将其用作PAO 10基础油添加剂时能很好的改善基础油的摩擦学性能,其中S-COFs-160样品的效果最佳,当添加量为0.5 wt%时,对比基础油,摩擦系数降低了57.2%、磨损体积减小了46.3%。结论反应温度越高,S-COFs纳米材料的成核速度越快、尺寸越小,越有利于纳米材料进入摩擦副滑动界面;高活性硫元素和三嗪环基团不仅能在金属摩擦副表面以配位相互作用形成稳定的吸附保护膜,而且在摩擦中能发生摩擦化学反应形成反应膜,二者的协同作用可有效地控制摩擦、抑制磨损和改善润滑。

Purposes—To study the friction reducing and anti-wear properties on steel/steel friction pairs of covalent organic framework nanomaterials with high active sulfur by synthesizing it and adding it as nano additives into the base oil poly-α-olefin 10(PAO 10)and to reveal its possible lubrication mechanism.Methods—Thioether bridged triazine based covalent organic frameworks(S-COFs-T,T=80,120,160)were synthesized with solvothermal method by using thiocyanuric acid and cyanuric chloride as raw materials at different temperatures.The physicochemical and tribological properties of such nano materials were characterized by X-ray powder diffractometer,X-ray photoelectron spectrometer,simultaneous thermal analyzer,scanning electron microscope,micro vibration friction and wear tester and three-dimensional optical profiler.Result—The higher temperature is applied,the intenser crystalline appears for S-COFs-T nano materials,and the smaller the size become with the layered structure.As the lubricant additive,S-COFs can efficiently improve the tribological properties of PAO 10 base oil.Among them,the S-COFs-160 sample shows the best effect.When the addition amount is 0.5 wt%,compared with the base oil,the friction coefficient and wear volume are reduced by 57.2%and 46.3%,respectively.Conclusion—The higher the reaction temperature,the faster the nucleation speed and the smaller the size of S-COFs nanomaterials,the more conducive the nanomaterials to entering the friction sliding interface.The high active sulfur elements and triazine ring groups can not only form the stable adsorption protection film on the surface of metal friction pair,but also form friction reaction film by tribo-chemical reactions.Consequently,the synergistic effect of both films can come true to control friction,impede wear and improve lubrication.