A New Hybrid Process for Repairbrazing and –Coating of Turbineblades

The aim of the research project is to combine repair brazing with protective coating against hot-gas corrosion into a common integrated process. Both the filler-metal as well as the hot-gas corrosion protection coating is applied by means of thermal spraying. The material layout is to be realised as far as possible near net shaped by using thermal spraying. The processes are to be operated in such a way that the brazing is integrated into the CVD diffusion annealing process as a TLP bonding process and, as a consequence, can be eliminated as a separate processing step. The thermal spraying processes APS, HVOF and CGS are to be qualified for this purpose. Thus the project's working hypothesis is to be able to transform thermal coating and joining processes into a common integrated hybrid process and, in doing so, obtain both qualitative and economic advantages. The importance of combining these processes lies in reducing the effort of grinding as well as economising on the vacuum brazing, which is currently a separate process step, and consequently lowering the production costs.