基于分子动力学的磁头磁盘界面润滑剂转移行为及实验研究

发布时间：2018-01-01 03:33

本文关键词：基于分子动力学的磁头磁盘界面润滑剂转移行为及实验研究　出处：《哈尔滨工业大学》2014年博士论文　论文类型：学位论文

【摘要】：硬盘作为主流的移动存储设备，读写数据的过程是依靠嵌入在磁头末端的读写元件来完成的。读写元件与磁盘之间的距离不断减小，以满足日益增长的大容量存储密度硬盘的需求。但随着磁头的飞行高度的降低，磁头/磁盘界面润滑剂转移问题成为影响磁头飞行高度、进而影响磁盘磁存储密度及磁头稳定性的关键因素之一。目前磁头的最低飞行高度已经下降到2nm以下，此时即使磁头与磁盘之间不发生接触，润滑剂也会在磁头与磁盘之间转移。因此研究磁头/磁盘未发生接触时磁头/磁盘界面的润滑剂转移，将有助于改善磁头飞行稳定性，减小磁头/磁盘发生接触的机会，进而增加硬盘的使用寿命。本文采用分子动力学方法，从微观角度揭示了磁头与磁盘未接触的情况下磁头/磁盘界面润滑剂转移机理，对其影响因素进行了仿真研究，并运用实验手段研究了磁头倾角、磁头动态倾角等因素对磁头/磁盘界面润滑剂转移及磁盘上润滑剂分布的影响，分析了发生转移后的润滑剂在磁头工作表面上的运动规律。根据磁盘上DLC层与润滑剂分子之间的相互作用，采用分子动力学理论，构建了改进的粗粒珠簧模型。考虑到空气轴承压力差及磁盘转速的影响，基于改进的粗粒珠簧模型，建立了润滑剂转移模型。运用该模型从微观角度分析了磁头/磁盘之间润滑剂的转移过程。研究了当磁盘转动时，磁头空气轴承表面上凸台倾角对润滑剂转移的影响。此外，分析了DLC表层官能团的数量、DLC层表面粗糙度、磁盘表面凸起对润滑剂转移及润滑剂在磁盘上分布的影响。考虑磁盘表面润滑膜的厚度、HAMR磁头/磁盘界面局部温度升高、磁头飞行状态或空气轴承表面的差异造成的空气轴承压力差不同、润滑剂分子的断裂等因素，采用所建立的分子动力学模型，对磁头/磁盘之间润滑剂的转移量进行了仿真研究，分析了磁盘表面润滑膜厚度、不同种类润滑剂分子、磁盘表面局部温度差、空气轴承压力差、磁头/磁盘间隙、润滑剂分子碎片等因素对磁头/磁盘之间润滑剂转移的影响。研究了磁头的俯仰角和侧翻角对磁头/磁盘之间润滑剂转移和对磁盘表面润滑剂分布的影响。采用二次离子质谱仪和光学表面分析仪分别对磁头表面及磁盘上润滑剂的分布进行了分析；采用飞行高度测试仪研究了磁头的动态俯仰角及动态侧翻角对磁头/磁盘之间润滑剂转移的影响。实验时使用涂有3润滑剂的盘片来测量磁头的飞行高度，并使用电荷耦合摄像机观察转移到磁头上的润滑剂在磁头上的运动情况；使用涂有12润滑剂的盘片来研究磁头动态俯仰角和动态侧翻角对磁头/磁盘之间润滑剂转移的影响。实验研究表明，磁头侧翻角对润滑剂转移及润滑剂在磁盘上分布的影响大于磁头俯仰角；磁头动态侧翻角对润滑剂转移的影响大于磁头动态俯仰角。当磁头飞行在磁盘外侧时，，转移到磁头上的润滑剂流向磁头末端内侧；当磁头飞行在磁盘内侧时，转移到磁头上的润滑剂流向磁头末端外侧。
[Abstract]:The invention relates to a magnetic head / magnetic disk interface lubricant transfer problem , which can improve the flying stability of the magnetic head , reduce the chance of contact of the magnetic head / disk , and further increase the service life of the hard disk . In this paper , the mechanism of magnetic head / magnetic disk interface lubricant transfer under the condition of uncontact of magnetic head and magnetic disk is revealed by molecular dynamics method . The influence factors of magnetic head / disk interface lubricant are studied . The influence of magnetic head inclination angle and head dynamic inclination angle on magnetic head / magnetic disk interface lubricant transfer and lubricant distribution on magnetic disk are studied by means of experimental method . The motion law of lubricant on the working surface of magnetic head is analyzed . Based on the interaction between DLC layer and lubricant molecule on magnetic disk , the molecular dynamics theory is used to construct the modified coarse bead spring model . Based on the modified coarse bead spring model , a lubricant transfer model is established based on the modified coarse bead spring model . Considering the thickness of the disk surface lubricating film , the local temperature increase of the head / disk interface of the HAMR , the difference of air bearing pressure caused by the difference between the flying state of the magnetic head or the surface of the air bearing , and the fracture of the lubricant molecules , a molecular dynamics model is adopted to simulate the transfer amount of the lubricant between the magnetic head and the magnetic disk , and the influence of the factors such as the thickness of the lubricating film on the surface of the magnetic disk , the local temperature difference of the surface of the magnetic disk , the pressure difference of the air bearing , the magnetic head / disk gap and the molecular fragment of the lubricant on the lubricant transfer between the magnetic head / magnetic disk is analyzed . The effects of pitch angle and roll angle of magnetic head on lubricant transfer between magnetic head and disk are studied . The influence of dynamic pitch angle and dynamic side turning angle of magnetic head on lubricant transfer between magnetic head and disk is studied by means of secondary ion mass spectrometer and optical surface analyzer .

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TH117.2

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