Feb 20 2006
Rommma / Shutterstocl
The term “tribology” comes from the Greek word “tribo” meaning rubbing and “logy” meaning knowledge. The Greeks first applied tribology when they were attempting to understand the motion of large stones across the surface of the earth. Nowadays, tribology has expanded to include the systematic study of lubrication, friction, and wear.
摩擦学在各个技术领域都可以发挥关键作用。在数据存储和半导体的复杂技术行业中，摩擦学研究有助于增强抛光过程和数据存储基板的润滑。在航空航天和汽车等传统行业中，摩擦学研究有助于促进机械组件的寿命。
润滑剂
A number of industrial processes need a comprehensive understanding of tribology at the nanoscale. Lubricant development in the automobile sector is governed by the adhesion of nanometer layers (monolayers) to a material surface. The assembly of components can rely critically on the adhesion of materials at the nanoscale.
摩擦和磨损
许多常规工具可用于表征润滑，摩擦和磨损。最典型的特征工具是摩擦仪，它具有许多配置，例如在平坦，固定盘上的球和平坦的平面等。在纳米级产生运动非常困难。需要新的表征方法来理解纳米级的摩擦学。
研究纳米级摩擦学
目前，原子力显微镜被用作分析纳米级摩擦学的标准。AFM对摩擦学应用的自然扩展来自AFM在表面上的纳米大小的手写笔的运动。传统的摩擦学测试不是使用AFM进行的，但可以进行几种新的应用。
下面列出的是AFM在Tribology中应用的示例：
- Measurement of the thickness of liquid and solid lubricants that have nanometer or even monolayer thickness
- 直接3D可视化疤痕或表面上的磨损轨道
- Measurement of frictional forces at the nanoscale
- 评估纳米级的机械性能，例如弹性，硬度和塑性变形
- Surface characterization of texture, morphology, and roughness
Materials Suited for Analysis
A key advantage of the AFM for tribological research is that the AFM can be regularly used on all varieties of materials. Materials that are generally examined include ceramics, polymers, metals, semiconductors, optical materials, magnetic materials, and biomaterials. AFM investigations are commonly performed under ambient conditions. AFM studies can be carried out in a liquid or vacuum environment.
纳米级磨损分析
纳米级磨损的影响对于机器的稳定性和优化至关重要，因为精确机器中的公差被最小化。传统的显微镜（如光学和扫描电子显微镜）可以在二维中可视化磨损。例如，SEM可用于获得X-Y轴中磨损轨道的放大视图。但是，对于测量磨损轨道的深度是必要的。
The AFM enables direct 3D visualization of scars and wear tracks. The images can be presented in a 3D projection and a 2D projection. Direct measurement of wear track depth can be simply performed using a line profile obtained from the AFM image.
润滑剂研究
众所周知，测量<100 nm的表面上的润滑剂层会极大地影响润滑行为。必须将这种薄膜描述为制作增强的润滑膜。但是，润滑膜的纳米级表征非常具有挑战性。
Optical methods such as ellipsometers can be employed for measuring the lubrication thickness of large sections (>10 μm2) of a surface. Measurement of the localized (<1 μm) film thickness cannot be done with the ellipsometer.
在AFM中，将探针放置在悬臂的末端，从而通过观察悬臂的偏转来实现表面和探针之间的相互作用力的测量。当表面和探针之间的距离缩短时，被称为力/距离曲线的图给出了探针上的力。
力/距离曲线的性质受悬臂的力常数，探针几何形状，润滑密度和润滑厚度的约束。
The thickness of lubrication films can be directly determined by measuring the changes in force/distance curves in an AFM.
Frictional Forces
Friction between two surfaces relies on the mechanical and chemical interaction between the surfaces. Variations in chemical composition resulting in friction can be measured using the AFM. The method for measuring these forces is known as lateral force, or frictional force microscopy.
当探针在AFM中的表面上移动时，表面的化学成分的变化会导致探针位于其位置的悬臂扭转。因此，悬臂的扭转取决于表面和探针之间的摩擦。
Simultaneous Measurement of Topography and Friction Forces
The AFM can be used to measure topography and frictional force images at the same time. The topography image is obtained by tracking the vertical forces on the cantilever, and the friction image is obtained simultaneously by tracking the lateral motions of the cantilever.
Surface Texture/Morphology/Roughness
AFM在纳米级平面的表面上提供了很高的对比度。光学和电子显微镜没有能力解决可以使用AFM测量的表面纹理的能力。应用包括线条粗糙度测量，2D和3D透视的表面形貌的可视化以及面积粗糙度测量。在获得AFM图像后，可以计算所有常规区域和表面粗糙度因子。
Nanoscale Mechanical Properties
Mechanical properties like hardness, stiffness, elastic modulus, and compressibility, as well as material characteristics such as plastic deformation and fracture, can be examined using the AFM.
可以通过将AFM探针直接按在样品表面上，可以测试纳米硬度。但是，使用优化的纳米注册仪器是有益的。纳米识别器比AFM的主要好处用于纳米硬度测量值，即可以使用纳米插入器轻松获得校准的测量。
AFM可以轻松地用于测量用纳米插件制成的压痕的3D地形。AFM图像可以直接可视化断裂行为或材料变形。
诸如脉冲力模式之类的方法可用于测量样品在各个位置的刚度。这些数据可用于开发表面的刚度映射。刚度图只能在表面刚度小于悬臂刚度的样品上开发。这种刚度图像定期在聚合物样品上测量。
Incorporating a fixture to the stage of the AFM enables the examination of material behavior, such as plastic deformation and fracture. The fixture allows forming forces on a sample while AFM images are being captured. A range of materials can be studied using such a method.