Limits of defect detection during lock-in thermography on thermal spray coatings

The efficiency of non-destructive lock-in thermography for the (online) characterisation of thermally sprayed coats is portrayed in the article. The utilised test objects are varied systematically in order to be able to detect defect properties, testing conditions and physical coat material properties as test parameters within a wide scope. For the variations, the minimum defect sizes detectable by means of pulse-excited thermography are determined by measurements and are verified on selected cases using theoretical calculations. The utilisability of online pulse thermography in quality assurance is proven on demonstrator components.