【作者】 李坤；

【导师】 杨胜强；

【作者基本信息】 太原理工大学 ， 机械制造及其自动化， 2009， 硕士

【摘要】 液体磁性磨具是以载液、铁磁性颗粒、添加剂、磨料组成的悬浮体系,是一种新型的精密加工磨具。液体磁性磨具在无外磁场作用时,表现出良好的流体特性;在强磁场的作用下,它的粘度会在毫秒级的时间增加两个数量级以上,表现出类似固体的特性,其强度由剪切屈服应力表征,并且在一定范围内,随着外加磁场强度的增加而增加。而且液体磁性磨具粘度变化是连续的,也就是一旦去掉磁场又立刻恢复流体的特性。一般选用的铁磁性颗粒具有较大的比表面积和密度,在使用和放置过程中极易发生团聚和和沉淀,从而影响到液体磁性磨具的流变性能,直接制约这种新型磨具的应用和产品化。本论文采用加入表面活性剂和纳米颗粒的方法,以期解决液体磁性磨具的分散稳定性差、抗沉淀稳定等问题。本文立足于液体磁性磨具稳定性的基础研究。首先,在对液体磁性磨具分散机理的分析基础上,系统研究了表面活性剂对体系稳定性的作用。以测量悬浮液的沉降时间、粘度、再分散性的变化间接反映体系的分散稳定性。从理论上分析了表面活性剂可以增强液体磁性磨具中磁性颗粒表面电势,从而增加颗粒团聚的空间阻力。实验表明:在碱性环境中,聚丙烯酸(PAA)可以显著提高液体磁性磨具的分散稳定性,六偏磷酸钠在较宽的酸碱环境中都能提高液体磁性磨具的分散稳定性。其次,纳米二氧化硅因其特有的性质,对液体磁性磨具的分散性、抗沉降性都能起到改良和加强的作用。综合上述研究的基础上,制备了加入表面活性剂、纳米二氧化硅的液体磁性磨具。并对所制备的样品的分散性、再分散性、抗沉降稳定性、加工效果进行了研究分析。结果表明:用聚丙烯酸(PAA)和六偏磷酸钠作为改性剂,纳米二氧化硅作为分散助剂,所制备的液体磁性磨具均具有良好的分散性能和抗沉降性能,且使用寿命也较以前大大增强。更多还原

【Abstract】 Fluid-magnetic abrasive tool is a kind of new technology on precise abrasive tool, it is suspension system composed with carrier, ferromagnetic particles, surfactant and abrasive particle. It has typical fluid characteristics when there is no external magnetic field around it. But when a strong magnetic field is applied, the viscosity of it will increase more than 100 times within a few milliseconds, and it will show the characteristics those are resemble to solid. Its strength is described by shear stress, and with the increase of magnetic flux density, the strength increases. It should be noted that the Fluid-magnetic abrasive tool would show the fluid’s behavior back rapidly as soon as the external magnetic field is removed. The reason why the particles tend to reunite is the specific surface area is large of the magnetic-responsive particles; one of the reasons why the particles tend to settle is the large difference in density between the water and the metal magnetorheological activity of the material due to non-uniform particle distribution. It requires a relatively high shear force to re-suspend the particles after reunited and settled. This general character problem need urgently. This expectation of present paper is to solve the contradiction of disperser stability by the time, settling stability with the viscosity of system, by adding the surface active agent (dispersing agent), the nano- particles etc.This article bases in the Fluid-magnetic abrasive tool’s basic research. The first, research function of the surface active agent (dispersing agent) to the system’s stability after analyzed the disperse mechanism of the Fluid-magnetic abrasive tool. In the research, surveyed the difference of sedimentation time, viscosity, re-dispersion of the suspension to indirect check the dispersible stability of system. theoretically analyzed the surface active agent (dispersing agent) can be increase the surface electric potential of pellets in the Fluid-magnetic abrasive tool, At the same time, the steric repulsion increase between the pellets, the hindrance of reunite increase. The experiment indicated the polyacrylic acid in the aqueous alkaline medium, but sodium hexametaphosphate in relatively wide aqueous alkaline medium can obviously enhance the dispersible stability of the Liquid-magnetic abrasive tool. The second, nanometer silicon dioxide have many unique characteristics, it can enhance the anti- reunite ability, the anti-settling ability and the mechanics capability of the Fluid-magnetic abrasive tool.Finally in the experimental foundation former, prepared the Fluid-magnetic abrasive tool with adding the surface active agent, the nano-particles. And the disperser ability, the anti-settling ability, machining effect of the sample has investigated. The result indicated,prepares the Fluid-magnetic abrasive tool in this way can obtain the good dispersible ability performance, the anti-settling performance, the more service life.更多还原