Investigation on Ceramic–Metal Joints for Shaft–Hub Connections in Gas Turbines

This paper shows possibilities for joining ceramic rotors to metal shafts. The investigations presented include exemplary joining methods for shaft-hub connections for ceramic rotors in gas turbines, as positive, permanent locking, or a combination of both. Active brazing as well as the combination of brazing or adhesive bonding and positive locking are discussed. Different shaft-hub connections were tested. The results of experimental investigations as static shear, bending, and torsion tests as well as dynamic torsion tests will be presented. In addition to the experimental investigations, finite-element analyses were made. Elastic calculations on simple geometries have shown the influence of different parameters like the thermal coefficients and the geometry at the joint face. Calculations were done to reduce the induced tensile stress in the joint and to increase carrying capacity. The calculations were also transferred to the shaft-hub connections to optimize the geometry of the joint faces.