A thermographic procedure for the measurement of the tungsten carbide coating thickness

Mechanical components subjected to severe environments are usually coat with cermet based WC–Co–Cr thermally sprayed coating. The coating plays a very important role in improving a component’s survivability and operational performance. The coating thickness is not only a parameter of the geometrical property of the coatings itself, but also an important indicator for evaluating the coatings’ quality, performance and service life. The coating thickness needs to be controlled and mastered because it has a great influence on the final product performance. Non-destructive measuring techniques are indicated for coating thickness evaluation. In this paper, the thermographic non destructive technique has been applied to measure the WC-Co-Cr coating. A procedure based on the “long pulse” thermographic approach for the measurement of the tungsten carbide coating thickness has been proposed and a comparison has been made with the performance of the traditional pulsed thermographic technique. A calibration has been performed to evaluate the thickness of the coating and a prediction model has been proposed.