【作者】 张春丽；

【导师】 吴志申； 张平余；

【作者基本信息】 河南大学 ， 高分子化学与物理， 2013， 博士

【摘要】 本文研究了铜、硫化银纳米微粒作为润滑油（剂）添加剂时的摩擦学性能，考察其作为添加剂时的减摩抗磨作用机理。（1）铜纳米微粒和二氧化硅纳米材料作为润滑油添加剂时具有良好的润滑性能已被大量研究证实。由此我们采用溶胶凝胶法制备了二氧化硅担载包覆铜纳米微粒的复合材料，考察其作为水基添加剂时的摩擦学性能。以五水合硫酸铜为铜源，以水合肼为还原剂，氨水调节pH值，制备铜溶胶。在铜溶胶中加入巯基丙基3甲氧基硅烷的无水乙醇溶液。室温下搅拌反应8h以上。得到Cu/SiO₂复合纳米材料。所得复合材料为二氧化硅担载包覆铜的结构，铜纳米微粒均匀担载在网状二氧化硅中，在铜纳米微粒表面有一层二氧化硅包覆，有从而效阻止铜的氧化和团聚。分别采用红外光谱、X射线粉末衍射仪、透射电子显微镜、紫外可见分光光度计对复合纳米材料的尺寸、形貌和结构进行表征。深入系统研究Cu/SiO₂复合纳米材料作为水基润滑添加剂的摩擦学行为。通过SEM、EDS及XPS对磨斑表面进行了分析，探讨了其摩擦作用机理。结果表明：Cu/SiO₂复合纳米材料作为水基添加剂具有良好的减摩抗磨性能和极压性能，其在摩擦过程中形成的沉积膜包含有Cu及少量FeS、FeSO₄和SiO₂。（2）采用原位表面修饰技术在水相中制备了稳定的聚乙二醇单甲醚黄原酸盐修饰的水溶性铜纳米微粒，所得纳米微粒粒径均匀，无团聚现象。并以所得到的聚乙二醇单甲醚黄原酸修饰铜纳米微粒作为水基添加剂对其摩擦学性能进行考察。结果表明：聚乙二醇单甲醚黄原酸修饰铜纳米微粒作为蒸馏水添加剂时在含量为0.1%时即能有效提高其承载能力。当聚乙二醇单甲醚黄原酸修饰铜纳米微粒添加量为0.5wt%时，蒸馏水的PB值即增加到206N，当添加量为5wt%时，PB值增加到了696N。在0.5wt%—3wt%的范围内，随着Cu纳米微粒添加量的增加，其PD值也逐渐增大。当浓度增大到3wt%时，其PD值达到8000N以上。EDS及XPS结果显示在含有铜纳米微粒蒸馏水润滑下，摩擦过程中在磨斑表面形成了主要含有Cu及少量FeS和FeSO₄的润滑膜。EDX结果显示在磨斑表面磨痕较深处对应的铜元素含量较高，这表明铜元素对磨斑有修复作用。在摩擦过程中形成的铜润滑膜，能有效降低摩擦接触压，避免直接的钢钢接触，从而改善蒸馏水的摩擦学性能。（3）合成辛烷基苯酚聚氧乙烯醚黄原酸修饰的水溶性单分子层修饰铜纳米微粒，考察其作为蒸馏水添加剂时的摩擦学性能。研究了添加剂含量、转速、载荷改变时辛烷基苯酚聚氧乙烯醚黄原酸修饰铜纳米微粒作为水基添加剂的摩擦学性能。结果表明：辛烷基苯酚聚氧乙烯醚黄原酸修饰铜纳米微粒作为水基添加剂具有较好的减摩抗磨性能。在所选择的添加量范围内，在相同条件下，均能明显提高蒸馏水的减摩抗磨能力。添加量为0.3wt%时具有相对最优的摩擦学性能，此时在转速为1450rpm、1200rpm、800rpm、400rpm时都具有优良的润滑减摩抗磨性能。转速较高时，摩擦系数和磨斑直径基本随着载荷的增加而增加。在低转速时，摩擦系数随着载荷的增加而降低。磨斑直径随载荷增加变化不大。（4）通过在油胺中高温分解油酸铜的方法，设计制备无硫、无磷环境友好纳米Cu润滑油添加剂，FTIR结果显示所得铜纳米微粒表面同时存在油酸和油胺。并将所得到铜纳米微粒作为PAO6添加剂考察其摩擦学性能。结果表明：所得Cu纳米微粒作为润滑油添加剂时具有较好的抗磨性能，但并不能提高PAO6的承载能力。SEM及EDS结果显示，在磨斑表面有铜元素存在，这表明在摩擦过程中有铜沉积在摩擦接触区域，形成低剪切强度的润滑膜。由此提高基础油润滑性能。（5）采用绿色的无溶剂热分解单源前驱体方法制备了不同粒径的硫化银纳米微粒，并考察了其作为液体石蜡添加剂时的摩擦学性能。在制备反应过程中不需要溶剂及表面活性剂，因此是一种绿色且简便易行的制备方法。通过热分解具有不同烷基链长的黄原酸银前驱体可以控制所得硫化银纳米微粒粒径。当前驱体从辛烷基黄原酸银到十六烷基黄原酸银和二十四烷基黄原酸银时，热分解后所得硫化银纳米微粒粒径逐渐减小。硫化银纳米微粒的粒径随着前驱体中烷基链长的增长而减小。对其形成机理进行了推测：在前驱体分解的时候，有一部分黄原酸配体从前驱体中解离出来，化学吸附在生成的硫化银纳米核表面。随着前驱体烷基链长的增加，解离出来的配体能更有效的阻止纳米微粒的生长。所得纳米微粒随着前驱体链长的增加依次减小。将所得硫化银纳米微粒作为液体石蜡添加剂采用四球摩擦磨损试验机考察其摩擦学性能。研究结果表明：三种粒径硫化银纳米微粒均能提高基础油的摩擦学性能，以平均粒径约为10纳米的硫化银纳米微粒作为添加剂时具有最好的减摩抗磨效果。更多还原

【Abstract】 In this dissertation, copper and silver sulfide nanoparticles were synthesized by different methods. Thetribological properties of silver sulfide and copper nanomaterials as lubricant additive were studied toexplore the anti-wear and friction reducing mechanism.（1） Cu/SiO₂nanocomposite was synthesized by sol–gel method. The size, morphology and phasestructure of as-prepared Cu/SiO₂nanomaterials were analyzed by means of XRD, TEM and UV-vis wasmeasured in relation to surface Plasmon excitation of Cu particles. The tribological properties ofas-synthesized Cu/SiO₂nanocomposite as an additive in distilled water were investigated with a four-ballmachine, and the morphology and elemental composition of worn steel surfaces were examined. Resultsshow that as-synthesized Cu/SiO₂nanocomposite as a lubricant additive is able to significantly improve thetribological properties of distilled water. A protective and lubricious film composed of Cu and a smallamount of FeS, FeSO₄and SiO₂is formed on steel sliding surfaces lubricated by distilled water containingCu/SiO₂nanocomposite. During friction process Cu nanoparticles can be released from Cu/SiO₂nanocomposite to fill up micro-pits and grooves of steel sliding surfaces, resulting in greatly reducedfriction and wear of steel frictional pair via self-repairing. The state and thickness of the film formed on theworn surface is closely related to applied load; and Cu/SiO₂nanocomposite might be a promisingwater-based lubricant additive for steel-steel contact subjected to moderate load.（2） Cu nanoparticle surface-capped by methoxylpolyethyleneglycol xanthate was synthesized usingin-situ surface-modification technique. The tribological properties of as-synthesized Cu nanoparticle as anadditive in distilled water were investigated with a four-ball machine, and the morphology and elementalcomposition of worn steel surfaces were examined using XPS and SEM. Results show that as-synthesizedCu nanoparticle as a water-based lubricant additive is able to significantly improve the tribologicalproperties of distilled water, which is ascribed to the deposition of Cu nanoparticles on steel slidingsurfaces giving rise to a protective and lubricious Cu layer thereon. The tribological properties and antiwearmechanism of as-prepared surface-capped Cu nanoparticle as an additive in distilled water were discussed.The surface-capped Cu nanoparticles as additive in distilled water （mass fraction5%） can increase the PB values from88N of distilled water to696N.（3） Wate-soluble Cu nanoparticle surface-capped by po1yoxyethylene octylphenol ether xanthate wassynthesized using in-situ surface-modification technique. The tribological properties of as-synthesized Cunanoparticle as an additive in distilled water were investigated with a four-ball machine. We investigatedtribological properties of copper nanoparticles as water-based additive with the additive concentration,rolling speed and load. The results show that po1yoxyethylene octylphenol ether xanthate modified coppernanoparticles as distilled water additives can significantly improve the carrying capacity and anti-wear ofdistilled water. The surface-capped Cu nanoparticles as additive in distilled water （mass fraction0.3%） canincrease the tribological properties of distilled water when rolling speed are400rpm,800rpm,1200rpm,1450rpm.（4） We prepared Cu nanoparticles by thermolysis of copper oleate precursor in oil amine under240℃.The tribological properties of as-prepared Cu nanoparticles as lubricating additive in PAO6wereinvestigated using a four-ball friction and wear tester. Results show that as-synthesized Cu nanoparticles asa lubricant additive is able to significantly improve the tribological properties of PAO6. A protective andlubricious film composed of Cu is formed on steel sliding surfaces lubricated by PAO6containing Cunanoparticles. During friction process Cu nanoparticles can fill up micro-pits and grooves of steel slidingsurfaces, resulting in greatly reduced friction and wear of steel frictional pair via self-repairing.（5） Ag₂S nanoparticles with different diameters were prepared by solventless thermolysis of silveroctyl xanthate, silver hexadecyl xanthate and silver carnaubyl xanthate as single-source precursors.As-prepared Ag₂S nanoparticles were characterized by transmission electron microscopy, x-ray diffraction,and Fourier transform infrared spectrometry. Possible growth mechanism of Ag₂S nanoparticles wasspeculated. In the meantime, the tribological properties of as-prepared Ag₂S nanoparticles as additives inliquid paraffin were evaluated using a four-ball friction and wear tester. It was found that Ag₂Snanoparticles prepared from silver carnaubyl xanthate had the smallest mean diameter of10nm, while thesame products obtained from silver octyl xanthate and silver hexadecyl xanthate had a larger meandiameter of50nm and20nm. The three types of as-prepared Ag₂S nanoparticles as additives were all ableto improve the friction-reducing and antiwear properties of liquid paraffin, and as-prepared Ag₂Snanoparticles of the smallest average size possessed the best tribological properties for steel-steel pair. This could be because Ag₂S nanoparticles with a smaller mean diameter are easier to be deposited on slidingsurfaces and exert self-repairing function more efficiently.更多还原