A study on interpretation of backward radiation ultrasonic signals for the evaluation of CVD diamond coating layer

An automatic back-reflected Rayleigh surface wave measurement was used to evaluate chemical vapor deposit(CVD) diamond coated specimens which are expected to extend the lifetime of mechanical parts that are used severely abrasive conditions. The bonding quality of the interface between CVD diamond coating layer and Silicon substrate is severely influenced by different roughness and cleaning conditions. It is importantly necessary for the quantitative evaluation to improve the bonding quality of the CVD diamond coating layer, For this purpose, a unique signal processing method called Time Trace Angular Scanning(TTAS) was applied. This initial experimental result obtained in the present study demonstrates the high potential of the backward radiated ultrasound as a tool for nondestructive evaluation of very thin CVD diamond coating layer.