レーザー誘起超音波を用いた酸化皮膜の界面強度評価

抄録

This study evaluates adhesion strength of oxide films on steel substrate by using laser-induced ultrasonic wave. Strong pulsed laser irradiates onto the back surface of steel substrate, inducing ablation, and strong elastic wave propagation. The elastic wave propagates from the substrate to the coating surface. When a large stress is applied to the interface, delamination occurs. In parallel, the displacement waveform of the coating surface is measured with a laser ultrasonic interferometer, so that we identify the critical laser energy for the delamination occurrence. SEM (Scanning Electron Microscope) observation revealed that the oxide film had a multilayer structure. By using a laser microscope or XPS (X-ray Photoelectron Spectroscopy), the delamination interface is characterized in the oxide multilayer system. Furthermore elastic wave propagation is computed using FEM (Finite Element Method) to investigate the interfacial stress for delamination. As a result, we succeeded in estimation of adhesion strength of oxide films.