【作者】 欧忠文；

【导师】 丁培道； 徐滨士；

【作者基本信息】 重庆大学 ， 材料学， 2003， 博士

【摘要】 纳米材料具有很多异乎寻常的特性，有着极为广泛的应用前景，是当前材料科学的研究前沿。纳米材料在水相和油相介质中的分散稳定既是纳米材料走向应用的一项关键技术，又是急需解决的一个难题。为此，本文首先从理论上阐明了纳米粒子在油性介质中的分散行为特性、分散稳定机制，进而提出了改善纳米粒子在油性介质中分散性和分散稳定性的具体措施。为了获得分散稳定的纳米粒子分散系，首先合成了环烷酸盐类、烷基水杨酸盐类及其它油溶性羧酸盐，然后在设计合成包括胺基型、羧酸型、羟羧/胺羧型、异氰酸酯型和具有后反应特性五大类超分散稳定剂基础上，在液体石蜡、合成基础油和天然菜子油中加入自制油溶性有机盐和超分散稳定剂，通过油溶性盐与硫化氢、水合肼、连苯三酚反应，原位合成了包括软金属和硫属化合物在内的单组元、双组元、三组元、四组元、五组元纳米分散系61种。具有后反应特性的超分散稳定剂不仅具有超分散稳定作用，还可通过后反应直接生成纳米单元。纳米粒子在油性介质中的原位合成具有以下显著特点：①将纳米单元(无论是单组元还是多组元)的生成、粒度控制、抗团聚保护和纳米单元的高度分散、长效稳定在一个体系中一次性实现，既改善了性能，又简化了操作，还能大大降低现有方法中因纳米单元制备、后期处理和化学改性等带来的生产成本；②此外，纳米粒子的原位合成均在室温和无外加溶剂情况下完成，分散介质可根据需要进行选择，如液体石蜡、矿物基础油、合成基础油和石油醚、乙酸乙酯、甲苯等；③合成的纳米粒子在油性介质中具有高度分散、长效稳定特点；④分散系中纳米粒子含量可按设计要求来合成，最高含量可达10%以上。通过普通离心试验和高速离心试验对原位合成纳米粒子在油性介质中的分散稳定性进行了加速试验，结果表明：经过72 h普通离心试验没有任何纳米分散系发生两相分离，在非连续高速成离心条件下少数纳米分散系34 h后开始发生相分离，大部分纳米分散系经过56 h非连续高速成离心仍未发现有相分离迹象，说明无论在前普通离心场还是在高速离心场中纳米分散系均表现出极高的分散稳定性，能满足在重力场中长期储存的要求。用激光散射法和冷冻蚀刻电镜表征了原位合成纳米粒子的粒径、粒径分布和聚集状态，结果显示，纳米粒子为球形，裸露粒径为5-40 nm，粒子大小均匀、分布窄，粒子呈弥散性单粒子分布，无团聚现象。用四球摩擦磨损试验机和环块摩擦磨损试验机对部分原位合成单组元和<WP=5>多组元纳米分散系的摩擦学性能进行了评价，结果发现：①在绝大多数情况下，在所选择的试验载荷范围内纳米粒子的添加能明显改善油品的抗磨减摩性能和抗极压性能；②环块试验评价结果好于四球试验评价结果；③单组元纳米分散系的摩擦学性能与多组元纳米分散系的摩擦学性能相近。为了弄清纳米粒子油润滑摩擦学作用机制，通过SEM、EDS和XPS对磨损表面进行了表征。通过对摩擦学评价结果和磨损表面表征的分析，提出了纳米粒子油润滑摩擦学作用机制，认为纳米粒子对油品摩擦学性能的改善是以下三条途径共同作用的结果：①摩擦副表面短程作用力，如吸附、微区电磁场作用导致摩擦副近表面纳米粒子在表面的富集，使具有改善摩擦学性能的表面润滑层(膜)的厚度增加、强度增大；②表面富集的部分纳米粒子在摩擦条件下发生摩擦化学反应，生成新的表面润滑膜；③纳米粒子对摩擦副表面的优化，如机械抛光、填平表面纳米级微坑和表面微损伤等。针对纳米粒子的摩擦学作用机制，提出了纳米粒子最适宜于作为光滑表面，特别是超光滑表面的表面加工、表面微损伤自修复和表面润滑的油品添加剂或介质添加剂。为便于与纳米粒子的摩擦学性能进行比较，还对具有化学结构代表性的五种有机铅盐，即月桂酸铅、油酸铅、环烷酸铅、硬脂酸铅和烷基水杨酸铅的摩擦学性能进行了评价。结果表明不同结构的羧酸铅其油溶性、抗磨减摩性能以及抗极压性能存在较大差异，铅盐的摩擦学性能与羧烃基结构密切相关。环烷酸铅和烷基水杨酸铅具有最好的油溶性；月桂酸铅具有最好的抗磨减摩性能和抗极压性能。更多还原

【Abstract】 Nanomaterials, often referred as research forward field of materials science, have widely applied foreground because of their special physical and chemical properties. The dispersion capacity and stability of nanoparticles in water or oil-soluble media is one of the key technologies before nanomaterials could be applied, and is also a difficult problem to be urgently resolved. To resolve the above problems, the mechanism and dispersion behavior of dispersivity and dispersion stability of nanoparticles in nonaqueous medium were clarified, and the measures improving the above-mentioned performance were brought forward. The oil-soluble organic salts(including naphthenate, alkylsalicylate, saturated or unsaturated carboxylate), and five types of hyper-dispersion stabilizer( respectively possessing the anchoring groups end of oil-soluble polymeric chain, amino, carboxyl, amino-carboxyl, hydroxyl-carboxyl, isocyanato-)as well as hyper-dispersion stabilizer having post-reaction characteristic were successfully synthesized according to design performance. Sixty one kinds of nano-dispersion systems, including sulfide and soft metal of single-component, double-component, tri-component, tetra-component and five-component, were in-situ synthesized in oil-soluble medium, containing hyper-dispersion stabilizer self-made, by reacting oil-soluble organic salts with H2S, diamine hydrate, pyrogallic acid. Hyper-dispersion stabilizers possessing past-reaction characteristic have not only superior dispersive ability and stability characteristics, also product nanoparticles by its post-reaction with H2S or reducing agent. The remarkable characteristic of nanoparticle in-situ synthesizing in paraffin liquid, synthetic base oils and rapeseed oils is which can synchronously bring to success in a single system for the growth of particles, granularity control, agglomeration control, high degree dispersion and long lasting stability. To compare with existing methods, for example preparing nanoparticles in aqueous medium containing water-soluble organic compounds before dispersing nanoparticle in oil-soluble, in-situ synthesis method of nanoparticles can not only improve the dispersion and stability of nanoparticles in dispersion medium, predigest operating steps, but also remarkably reduce production costs. Furthermore, this method carries<WP=7>through in room temperature and has no use for additional solvent, and the dispersion medium can be selected according to needs, for instance liquid paraffin, mineral base oil, synthetic base oil, petroleum ether, ethyl acetate, toluene. The nanoparticles content in oil-soluble dispersion medium can be ensured according to practical requirement, and max could exceed 10 percent.The accelerated test used for evaluating the dispersivity and dispersion stability of nanoparticles in oil-soluble medium was carried through common speed centrifuge and high speed centrifuge. The results showed that none of all dispersion systems come into being delamination through 72 h uncontinuity(2 h period, 4~5 period per day) common speed centrifuge test, and a few appear delamination through 34 h high speed centrifuge test, but most don’t through 56 h . Those give the fact that dispersion systems possess very good dispersion stability not only in the common speed centrifugal field but also in high speed centrifuge field, and it could meet the need that the dispersion systems are long deposited in gravity field. The diameter, diameter distribution and conglomeration behavior of nanoparticles in dispersion medium was observed through freeze-etching replication transmission electron microscopy (ERTEM) technique and laser scattering methods. The results indicated that the nanoparticles scattering in medium, shape sphericity without agglomeration, the bareness diameter were 5~40 nanometer, the size of nanoparticles were uniformity. Their tribological properties of single or multi-component nano-dispersion systems as lubricating additives were evaluated with four-ball tribo-tester and ring block tribo-t更多还原