Infrared thermography to detect residual ceramic in gas turbine blades

A serious problem in the production of gas turbine blades is the detection of residual ceramic cores inside the cooling passages; in fact, the presence of even small ceramic pieces affects turbine performance and may cause difficulties in successive manufacturing. Therefore, it is important to have a non-destructive technique that must be capable of detecting tiny ceramic fragments in a fast and easy way. In this perspective, the suitability of infrared thermography was investigated within cooperation between the University of Naples and the Europea Microfusioni Aerospaziali S.p.A. (EMA). Several blades of three different types were inspected revealing that in many cases infrared thermography can discover small ceramic fragments which were missed by X-ray inspection. In addition, infrared thermography allows gaining of information about other types of anomalies (e.g., surface defects) during the same testing step (by eventually changing the test parameters) and then saving time and money. The obtained results look promising in view of introducing infrared thermography among industrial instrumentation as an alternative to, or integrated with, the most currently utilized non-destructive techniques.