Evaluation of CVD diamond coating layer using leaky Rayleigh wave.

Area of Science:

• Materials Science
• Nondestructive Testing
• Acoustic Wave Propagation

Background:

• Chemical vapor deposition (CVD) diamond coatings offer unique properties but require reliable evaluation methods.
• Nondestructive testing (NDT) is crucial for assessing coating integrity without damage.
• Leaky Rayleigh waves are sensitive to surface and near-surface properties.

Purpose of the Study:

• To investigate the feasibility of employing leaky Rayleigh waves for nondestructive evaluation of CVD diamond coatings.
• To develop and validate a novel signal analysis technique for improved NDT of these coatings.

Main Methods:

• Experimental setup using an immersion, pulse-echo system to measure leaky Rayleigh waves.
• Development of a "time trace angular scan (TTAS)" imaging technique for signal analysis.
• Application of TTAS imaging and backward radiation profiles for data interpretation.

Main Results:

• The TTAS image effectively captures time-of-arrival and angle-of-incidence information.
• "Time-angle windowing" using TTAS facilitates precise signal selection.
• Backward radiation profiles of windowed signals yield parameters for coating evaluation.

Conclusions:

• Leaky Rayleigh waves, analyzed with the TTAS method, provide a viable NDT approach for CVD diamond coatings.
• The proposed TTAS technique enhances the accuracy and reliability of evaluating coating characteristics.
• This method offers a promising tool for quality control and integrity assessment of diamond coatings.