Ceramic matrix composites (CMC) are characterised by their resistance to high temperatures and corrosion, their damage tolerant behaviour, and low density. They are therefore suited for use in extreme environments and above all else in the aerospace industry, as for example in satellite structures. Other areas of application are the car industry in brake or clutch disks and in mechanical engineering in protective sleeves for pumping applications.

At the Institute for Materials Resource Management, researchers have for the first time developed a method that can be used to repair localised damage in CMC components.  

Repairing components, avoiding rejects

Full functionality of CMC materials is indispensable in sensitive areas of application. Yet localised material defects or damage to components during the manufacturing and utilisation phases is often unavoidable. Up until now, it has not been possible to repair locally damaged CMC components so that they could continue to be used. CMC components damaged during the manufacturing process were disposed of directly as rejects. Damage occurred during the utilisation phase leads to component failure, replacement, and disposal.

“With the new process, we are showing a realistic possibility for repairing components that have been damaged during the manufacturing process so that they can be used, even in demanding aerospace applications,” says Prof Dietmar Koch, professor for materials engineering, who is leading the project “Repair Concepts for Reduced Reject Rates of virgin and overhauled CMC (R4CMC).

Repair processes developed

R4CMC was funded by the Bavarian State Ministry for Economic Affairs, Regional Development and Energy with the aim of closing this significant gap in CMC material research and manufacturing. Together with a consortium from industry and research as part of the AI Production Network Augsburg, the Chair of Materials Engineering at the Institute for Materials Resource Management worked on the development of repair concepts for locally damaged ceramic matrix composites made of carbon fibre-reinforced silicon carbide (C/SiC) and silicon carbide fibre-reinforced silicon carbide (SiC/SiC).

The focus lay on CMC materials that were damaged during the industrial manufacturing phase. During the project, which ran for three years and ended at the end of 2024, the consortium was able to successfully develop repair processes, which through the removal of the damaged area and its filling with ceramic inlays, for example, restored the functionality of the damaged CMC material.

“Through the development of new materials-related process technologies, the project contributes to saving resources in the manufacturing phase and to increasing the material efficiency of ceramic matrix composite materials, which brings ecological and economic advantages for the use of CMCs,” says Koch. Researchers at the Chair of Materials Engineering will further explore these aspects in a follow-up project.