Scanning probe microscope probe switching unit with electrical measurement for in situ multifunctional characterization: Design and preliminary application in tribocorrosion investigation

Scanning probe microscope (SPM) is a potent tool in nanotribology research. However, commercial environment control SPMs can install only one probe to perform one function at a time. Accordingly, this study developed a probe switching unit with electrical measurement for in situ multifunctional characterization. The unit mainly comprises a cover, a rotation stage, and a probe holder assembly. Four probes can be installed. One is electrically connected to perform tapping mode and electrical measurement such as Kelvin probe force microscope (0.01 mV resolution), while the other three are to perform contact mode. The rotation stage drives the assembly to switch probes to in situ measure multiple physical quantities in a controlled environment. The unit was preliminarily applied to investigate tantalum tribocorrosion. Based on the changing trends of wear amount and surface potential change, the wear process can be roughly divided into three stages, which may be caused by desorption of the adsorbed air, wear of the oxide film, and wear of the substrate, respectively. Moreover, wear can lead to a surface potential increment, which may partly contribute to the galvanic corrosion between the virgin area and the wear area. The unit may serve as a useful tool for nanotribology research.