Systematic investigation of wear-induced cold welding in ultrahigh vacuum piezoelectric motors with non-metallic coatings

Piezoelectric motors are widely used in various applications where both precision positioning and miniaturization required. Inertial or quasi-static commonly employed because of their high accuracy, which demands consistent sliding friction between moving sliders static counterparts for reliable operation. In general, slider wear is unavoidable after long-term use. This can often lead to more serious cold welding vacuum, also referred as induced by direct contact similar metal surfaces. Non-metallic coatings prevent such unwanted ultrahigh vacuum (UHV) applications. However, the practical reliability available under UHV conditions still remains be elucidated. Here, we systematically investigate used, UHV-compatible lubricant piezoelectric vacuum. We demonstrate that polytetrafluoroethylene (PTFE) shows most operation while other eventually wear-induced motor failure. Our findings provide a simple effective method improve performance coating surface with PTFE.