The TurbAn project, carried out by Schunk Kohlenstofftechnik GmbH (SKT) from 1 December 2018 to 31 November 2022, was funded under the German federal grant 03XP0189D. Its goal was to advance both oxidic (Ox/Ox) and non‑oxidic (SiC/SiC) ceramic‑fiber composites for aerospace applications. The project budget was spent mainly on acquiring expensive ceramic fibers and fabrics and on the processing steps required to produce an optimized material suitable for turbine components. The research team, led by Dr. J. Schmidt, L. Zulauf, Dr. T. Wamser and Dr. F. Reichert, worked closely with the partners HTL and RRD, who contributed expertise in fabrication and mechanical testing. The project’s results were documented in a report dated May 2023 and are slated for publication in peer‑reviewed journals.

In the Ox/Ox development phase, SKT produced plate specimens from four different weave types: SKT 1, SKT 2, SKT 3 and the commercial 3M‑DF11. The plates were fabricated by manual prepregging of a water‑based resin, followed by vacuum bagging and autoclave curing. A partial factorial design was used to limit the number of expensive fabric combinations; the key variables were weave architecture, sintering temperature (± 50 °C from the standard) and target fiber‑volume fraction (35 % or 40 %). Plate dimensions of 325 × 325 mm were chosen to minimise waste while providing sufficient material for testing. Mechanical testing, including 4‑point bending and tensile tests, revealed that specimens made with the SKT 3 weave consistently met the target values for strength and stiffness. Green‑highlighted cells in the results table indicate that most of the target criteria were achieved, and statistical analysis confirmed the influence of the selected parameters. The successful plates had a sintered thickness of approximately 3 mm and a fiber‑volume fraction close to the design goal. The project also demonstrated that the matrix system remained stable across the temperature range, suggesting that further optimization could raise the mechanical performance even further.

The SiC/SiC part of the project focused on improving the microstructure and mechanical properties of silicon‑carbon‑silicon composites. Iteration 3.2 of the SiC/SiC material, produced by a densification process that prevented silicon attack on the fibers, showed a dramatic improvement over the previous iteration. The 4‑point bending strength increased to 428 ± 35 MPa and the tensile strength to 255 ± 13 MPa, with elongations of 0.30 ± 0.02 % (bending) and 0.22 ± 0.02 % (tension). These values represent roughly a two‑fold increase compared with iteration 3.1. Micro‑CT and optical microscopy revealed a dense SiC‑CVI matrix and characteristic fiber‑pull‑out failure, confirming the damage‑tolerant behavior expected of SiC/SiC composites. The material also met the TurbAn minimum criteria: porosity below 5 %, bending strength above 300 MPa, tensile strength above 250 MPa, and a reduction in bending strength after oxidation of less than 30 %. These results indicate that the optimized SiC/SiC composite is a viable candidate for high‑temperature turbine components.

Overall, the TurbAn project achieved its technical objectives by producing ceramic‑fiber composites that meet stringent aerospace requirements. The collaboration between SKT, HTL, and RRD enabled a comprehensive approach that combined advanced fabrication techniques, systematic design of experiments, and rigorous mechanical testing. The project’s findings will be disseminated through planned publications, contributing to the broader field of high‑temperature composite materials.