In order to effectively detect the surface cracks on thermal barrier coatings (TBCs)

the applicability of immersion ultrasonic testing method was studied. The TBCs samples were fabricated by the air plasma spray (APS)

which was most commonly used in the TBCs process. The surface cracks with different depth

width and length were characterized by echo path difference and C scan image. Results indicated that the substrate materials had no obvious influence on the immersion ultrasonic testing results. By optimizing the detection parameters and selecting the instruments and probes properly

the surface crack with the depth of 0.1 mm and the length of 2 mm can be detected effectively by the immersion ultrasonic testing method. The length and depth of the surface cracks on TBCs can also be achieved by immersion ultrasonic testing method

make it an effective way to solve the TBCs surface cracks detection problem.