基于原子力显微镜的钛酸钡和PVDF机械、
摩擦性能研究
研究生：钱益心
指导老师：陈云飞
东南大学机械工程学院，南京
摘要
当机械进入微观领域，表面力如粘附力与摩擦力等已经成为影响器件寿命与性能的关键因素。研究表明，微纳尺度下，摩擦能耗主要有声子耗散和电子耗散。目前对于电子耗散的影响尚不明确，而钛酸钡和PVDF作为压电材料，表面受力会产生极化电荷，是研究电子摩擦非常理想的材料。原子力显微镜（AFM）以其超高空间分辨率及超高力学灵敏度广泛应用于微纳尺度下材料的电学、力学等性能研究。因此，本论文基于AFM对钛酸钡和PVDF的机械性能及摩擦性能进行研究，并探讨表面电荷密度对摩擦力的影响。
材料的机械性能在一定程度上会影响摩擦力，所以本文首先基于Oliver-Pharr和Hertz模型，利用原子力方脸适合的短发
闪离显微镜测得钛酸钡和PVDF的弹性模量分别约为290GPa和500MPa。其次，开展了纳尺度下粘附力、AFM探针扫描速度以及针尖施加的正压力等因素对摩擦力影响的研究。实验结果表明，摩擦力随着探针和材料间粘附力增大而增加；随着扫描速度的增大，摩擦力小幅度增加；钛酸钡材料中，摩擦力与正压力呈线性关系，符合传统的Amontons定律，PVDF材料中，摩擦力与正压力呈线性关系在法向载荷较小时成立，但是随着法向载荷进一步增大，压电材料形变引起表面粗糙度的增大和表面电荷密度的增加，摩擦力呈现非线性增加的趋势。然后，通过电压调控PVDF 表面电荷密度，进一步研究了表面电荷密度对摩擦力的影响。实验结果表明，形变引起压电材料表面粗糙度的增大对摩擦力的影响较小，压电材料中摩擦力随正压力的增加而非线性增加的原因主要是形变引起的表面电荷密度的增大。
综上所述，本文利用原子力显微镜实现了纳尺度下压电材料杨氏模量等机械性能的精确测量与评价，同时发现了压电材料的表面电荷密度与其摩擦性能存在一定程度的依赖关系，有望通过这种方法实现对材料摩擦性能的主动调控。
关键词：钛酸钡，PVDF，电子摩擦，原子力显微镜，摩擦力
枯萎近义词
Mechanical and Frictional Investigation of Barium Titanate and PVDF Bad on Atomic Force
Microscopy
School of Mechanical Engineering, Southeast University
ABSTRACT
When machinery entered the microscopic field, surface forces like adhesion force and friction force have become the key factors for device lifespan and performance. At the
micro-nano scale, rearch shows that frictional energy consumption mainly includes phononic dissipation and electronic dissipation.At prent, the influence of electronic dissipation is not clear. Barium titanate and PVDF are piezoelectric materials, so they can generate polarized charge on the surface under pressure, which make them become ideal materials for studying electronic friction. Atomic Force Microscopy (AFM) has been widely ud in the measurement of electrical and mechanical properties of materials at micro-nano scales due to its ultra-high spatial resolution and measureing nsitivity. Therefore, in this thesis, the mechanical properties and frictional properties of barium titanate and PVDF were studied using AFM, after which the effect of surface charge density on friction was discusd.
The mechanical properties of the material will affect the friction to some extent. Therefore, bad on the Oliver-Pharr and Hertz models, the elastic modulusi of barium titanate and PVDF were measured by atomic force microscopy and the values were about 290 GPa and 500 MPa, respective
ly. What's more, the effects of adhesion, scanning speed of the AFM probe, pressure exerted by the tip on the friction were studied. The experimental results show that friction increas with the increa of the adhesion between the probe and the material. As the scanning speed increas, friction increas slightly. For barium titanate, friction increa linearly with the positive pressure, which obeys the traditional Amontons law. For PVDF, the linear relationship between friction and positive pressure is valid under relatively small load. As the normal load increas, friction has a tendency to increa nonlinearly. The reason for this phenomenon are the increa of surface roughness and surface charge density caud by the deformation of the piezoelectric material. Then, the effect of surface charge density on friction is further studied by applying voltage. The experimental results show that the increa of the surface roughness has little effect on the friction. While the ri of surface charge density contributes greatly to the increa of friction force.
In summary, the atomic force microscopy is ud to accurately measure and evaluate the mechanical and frictional properties of piezoelectric materials. At the same time, it is found piezoelectric materials has a certain degree of dependence on surface charge density and it is expected that friction can be actively regulation achieved by this method.
Key words: barium titanate, PVDF, electronic friction, atomic force microscopy, the friction force
目录
摘要..................................................................................................................................................... II 第一章绪论. (1)
1.1 课题研究背景 (1)
1.2压电铁电材料简介 (3)
1.2.1钛酸钡简介 (3)
合作的名言1.2.2PVDF薄膜简介 (5)
1.3 国内外研究现状 (5)
马云创业经历
1.4论文研究内容及意义 (10)
第二章原子力显微镜的简介及探针参数校正 (11)
2.1 原子力显微镜的简介 (11)
2.1.1 原子力显微镜的工作原理 (11)
2.1.2 原子力显微镜的工作模式 (12)
2.2 探针简介及其参数校正 (13)
2.2.1 AFM核心部件—探针 (14)
2.2.2探针的法向灵敏度校正 (14)
青木瓜怎么吃2.3.3 探针的侧向灵敏度校正 (17)
建筑类大学排名2.3 粘附力与摩擦力的测量与计算 (19)
孝贤纯皇后2.3.1 粘附力的测量 (19)
2.3.2 摩擦力的测量 (21)
2.4 本实验设备 (22)
第三章纳米材料的弹性模量理论与实验结果 (25)
3.1 Oliver-Pharr（OP）法计算材料的弹性模量 (25)
3.2 Hertz模型简介 (29)
3.3 实验步骤 (33)
3.4 弹性模量测量结果 (35)
3.5 本章小结 (36)
第四章钛酸钡和PVDF纳米摩擦性能的实验研究 (38)
4.1 实验准备 (38)
4.1.1 样本处理与表征 (39)
4.1.2 ORCA电压调控模块 (41)
4.2 粘附力的测量 (42)
4.3 表面粗糙度的测量 (44)
4.4 扫描速度对压电材料摩擦性能的影响 (45)
4.5 正压力对压电材料摩擦性能的影响 (47)
4.6 表面电荷密度对压电材料摩擦性能的影响 (52)
4.7 本章小结 (52)
第五章总结与展望 (54)
5.1 总结 (54)
5.2 展望 (55)
致谢 (56)
参考文献 (57)
攻读硕士学位期间发表论文 (65)
