DEVELOPMENT OF REPAIR METHODS FOR SINGLE CRYSTAL COMPONENTS USING THERMAL SPRAY PROCESSES

Gas turbines operate in a demanding, extremely harsh environment. High temperatures over 1000 °C as well as mechanical and chemical stresses in this area lead to damage of the components. As the production of the complex turbine blades is cost-intensive, component repair is desirable from an ecological and economic point of view. As a result, interest in suitable repair technologies for gas turbine components is growing steadily.

Therefore, the aim of this work is to produce CMSX-4 repair coatings on a CMSX-4 substrate. For the production of these coatings the Cold Gas Spraying process was used. In order to identify the optimal process parameters, gas pressure, gas temperature as well as the spraying distance were varied in a series of experiments. However, it turned out that the manufacture of high-quality coatings was difficult. To identify the reasons, the powder properties were investigated in more detail using XRD and TEM. In addition, single splat experiments were conducted to gain a more precise understanding of the layer formation. The investigations suggest that due to brittle material behavior, larger particles in particular break on impact. Therefore, in further experiments, finer powder fractions will be investigated.