Nondestructive Evaluation of Locally Repaired Coating for Gas Turbine Blades

Ultrasonic examination methods have been developed to qualify the locally repaired coating on gas turbine blades. The acoustic velocity of the MCrAlY coating obtained by Inert Gas Plasma Spray (IGPS) has been measured and compared with that of Vacuum Plasma Spray (VPS) coating. The thickness of the locally repaired coating on specimens and blades has been evaluated. The coating adhesion on the base material and its distribution have been investigated by A-scan and C-scan data display methods. The influence of surface roughness on the test results has also been examined.Copyright © 1996 by ASME