【作者】 郭红；

【导师】 刘佐民；

【作者基本信息】 武汉理工大学 ， 机械设计及理论， 2008， 博士

【摘要】 基于固体润滑材料的物化特性和键能理论以及硅油的高温稳定性创新出的BN-C-硅油复合胶体,拓宽了多元润滑体复合理论和硅油的工业应用领域。本文在回顾胶体科学发展概况的同时,综述了胶体中分散相超微/纳米颗粒的复合方法及其在润滑领域的应用现状。在此基础上,提出了高温超微/纳米胶体润滑新概念,并以硅油为基,包覆BN-C固体润滑剂制备出高温润滑复合胶体。基于BN和C具有相似的物化特性、晶体结构和润滑互补特性,本文探讨了两者之间的复合匹配性,并根据固体与分子经验电子理论(EET)对BN及BN-C复合物的价电子结构进行了分析。研究表明:BN-C复合物的层间键能(0.25673374 kJ/mol)小于BN的层间键能(0.33129492kJ/mol),如果两者复合,其复合物的层间滑移更为容易,可获得低摩擦系数的复合固体润滑颗粒。为了实现超微/纳米BN-C颗粒的复合,本文对行星式高能球磨机进行了改进设计,增加了偏心机构,从而提高了碰撞能量。通过对该高能球磨机球磨过程中磨球的动力学和运动学分析,研究了被研磨颗粒的受力、变形以及其研磨效率,得出研磨效率与公转速度、公转/自转比例系数、偏心距和磨球直径等之间的关系,为超微/纳米胶粒的制备工艺参数的设定提供了依据。为了提高BN-C超微/纳米胶粒的分散稳定性,使其能稳定地悬浮于硅油中,本文基于胶体理论,加入非离子性表面活性剂,探讨了其组分和配方及其对BN-C超微/纳米胶粒的修饰和包覆。建立了胶粒尺寸与其沉降速度的关系模型,模拟得出当BN-C胶粒的粒径小于284.7nm时,该复合胶粒可以稳定悬浮于硅油中,为BN-C-硅油复合胶体的制备和分散稳定性提供了重要理论依据。文中采用SEM和EDS分析了超微/纳米胶粒的粒度分布状况和组成元素。并通过FTIR和XPS对复合胶粒所含元素的成键状态进行了分析研究,发现采用文中所述的制备工艺可使BN-C形成B、C、N三种元素原子级结合的化合物。XRD对复合胶粒的结晶状态分析说明形成的新化合物为与h-BN晶体结构相似的六方化合物。结合前面所述基于EET理论进行的滑移理论分析,该研究为润滑机理的探讨提供了依据。采用XP-5型销盘式摩擦磨损试验机研究了本文所制备的高温复合胶体的润滑性能,实验证实了无论在常温还是高温下,该胶体都具有优良的润滑性能。结合文中所做的微观分析,探讨了胶体的高温润滑机理。最后以发汗金属陶瓷烧结体为典型对象,研究和验证该复合胶体的浸润性。更多还原

【Abstract】 The BN-C-silicone oil composite colloid, which is manufactured by innovation based on the physicochemical characteristics of solid lubricants and the theory of bond energy, as well as the stability of silicone oil at elevated temperature, has enriched the recombining theory of multivariate lubricants and widened the industrial application fields of silicone oil.In the thesis, the development situation of colloid science, the preparation methods of ultra-micro/nano composite particles and their application status in lubrication field were summarized. Based on the review, a new concept about high temperature ultra-micro/nano lubricating colloid was presented. And silicone oil was adopted as the dispersing medium to prepare BN-C-silicone oil composite colloids with high temperature lubricating property by using high energy ball milling method.Based on the similar physical properties and similar crystal structure, together with the complementary lubricating properties, BN and C matched well when they were recombined. According to analyzing the valence electronic structure of BN and BN-C based on Empirical Electron Theory (EET), it was found that the lamellar bonds energy of BN-C compound (0.25673374 kJ/mol) was lower than that of BN (0.33129492kJ/mol), which meat that the slip between layers was easier to happen in BN-C compound. And lower lamellar bonds energy led to the smaller frictional coefficient.To achieve energy enough for the recombination of BN-C ultra-micro/nano particles, the planetary high energy ball mill was improved. An eccentric part was added to improve the impact energy of the planetary high energy ball mill. Then the stress, deformation of the particles and the milling efficiency were discussed through analyzing the kinetics and kinematics of the balls during the milling process. It was found that the milling efficiency was relative with revolution speed, proportion of revolution speed to rotation speed, eccentric distance and the diameter of the milling balls. These could be the theoretical reference for setting the milling technic parameters to prepare the ultra-micro/nano particles.Based on the colloid theory, nonionic surfactants were added to make the BN-C ultra-micro/nano composite particles suspend in silicone oil stably and avoid particle agglomeration. And the proportion of the selected surfactant was discussed. Then the surface modification mechanism of the colloidal particles was also discussed. Through modeling the relation between the size of particles and sedimentation speed, it was found that the BN-C particles could suspend stably in silicone oil if their diameters were less than 284.7 nm. These were the important theoretical basis for the preparation and dispersion stability of the colloid.The diameters of the ultra-micro/nano colloid particles and the elements in the particles were measured by SEM and EDS. And through analyzing the binding status of the colloid particles by using FTIR and XPS, it was found that the new compound was formed by B, C and N combining in atomic ways. The XRD analysis showed that the new compound had hexagonal crystal structure, which was similar to h-BN. Together with the theoretical slip analysis based on EET, this could be used for discussing the lubricating mechanism.The lubricating properties of the prepared composite colloid were measured by using XP-5 friction and wear tester. It was found that the colloid showed good lubricating property at whatever ambient and high temperature. And based on the microscopic analysis, the lubricating mechanism was discussed. Finally, considering the structure characteristic of the sweat-gland ceramic sinter, the lubricity of the colloid infiltrated in the sinter was also studied.更多还原