Ultra-Thin Film Ultrasonic Characterization

Ultrasonically induced nanoscale fatigue and friction reduction phenomena are researched for nanometer order thick protective overcoats. The newly developed method described here is a synergy of the nanometer scale quantitative nanoindentation/scratch technique and ultrasonic excitation. A standing ultrasonic wave is generated at the sample holder during the quasi-static nanoindentation/scratch test at an excitation frequency of several hundreds of kilohertz. Due to the fact that high strain rates are being generated at the surface of the sample, nanofatigue phenomenon followed by delamination and overcoat chipping can be observed. Statistical investigation of fatigue inducing parameters, such as critical quasistatic load and amplitude of oscillations, leads to a means of comparative sample characterization.