Because of the growing economic significance and the increased use of thermally sprayed coatings suitable testing methods have to be provided, by means of which the demanded characteristics of a coating can be detected by non-destructive testing. For the detection of inadmissible coating properties like deviations from the desired coating thickness, interface defects and cracks the CS pulsed eddy current method (CS: controlled signal) is particularly suitable due to its high flaw detection capability and because it is easy to automate. However, on account of inadequate probe orientation on complex component geometries as well as under the influence of strong disturbances caused by the superposition of coating thickness variations and flaws in the coating the sensitivity of this method is reduced. The paper describes the improvement in flaw detecting achieved by designing the transmitting and receiving units for high frequencies, manipulator-supported positioning of the test probe and the use of digital filter algorithms.
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