Laser-Ultrasonic Evaluation of Thermal Sprayed Coatings

摘要

The non-destructive characterization of thermal spray coatings is of particular importance for quality control, but it can be also very useful for understanding the mechanical and thermo-mechanical behavior of parts allowing the development of life prediction models. The laser-ultrasonic technique presents many advantages over conventional ultrasonic techniques for this application. In this paper, some recent works on the characterization of thermal sprayed coatings by laser-ultrasonics are presented. First, the use of surface acoustic waves to obtain elastic properties, density and thickness of dense coatings is considered and results obtained with WC-Co coatings are presented. Second, elastic property measurements on thermal barrier coatings are introduced and, finally, results on the detection of defects like vertical cracks and coating disbonding for dense coatings are discussed.