Inspection of HVOF-coated Pelton wheels using active thermography

EDF is performing an experimental study aimed at covering Pelton wheels with hard coating HVOF (High Velocity OxyFuel), which would provide a better abrasion resistance of the wheels. The need for detecting underlying defects and the lack of sensibility of traditional MT (Magnetic particle Testing) in this case made EDF look at others non destructive examination techniques. Feasibility tests were at first led using representative mock-ups and an active thermography inspection system developed by AREVA NDE Solutions called the Photo-Thermal Camera (PTC). Further tests were then realized on real Pelton wheels under fully realistic conditions.