AFMによる油環境下での表面間相互作用力の直接測定

抄録

There are two types of friction modifiers (FMs) used as lubricant additives: Reaction film FMs (RF-FMs) and adsorption film FMs (AF-FMs). While RF-FMs provide good performance in severe condition, AF-FMs excels in mild condition. These empirical evidences lead us to combining these two FMs to cover broader condition. However, the effects of their combination are highly complicated due to the interaction between these FMs. For example, it was shown that the RF-FMs of MoDTC(MoS₂) promotes absorption force of an AF-FMs. If the interaction force of AF-FMs with various materials can be evaluated, it would help us to improve tribological performances of lubricants. Although a scanning probe microscope (SPM) seems suitable for this application, we found some obstacles to achieve proper measurements of pull-off force due to static electricity, laser position to cantilever, installing and removing of cantilever, sample deformation and so on. In this study, we try to measure the adsorption force between the colloidal probe chemically-modified with COOH group and the surface and we thoroughly investigated those effects and mesurement error on pull-off force quantitatively. We propose a calibration method of PD sensitivity (proportional constant) and present some important aspects of the proper measurement of adsorption forces.