- Ceramic Matrix Composites (CMC) are light weight materials with high specific strength, a high temperature resistance, and high resistance to corrosive environments [1]. Ceramic fibers embedded in a ceramic matrix thereby overcome the disadvantages of conventional technical ceramics and allow applications that go beyond the possible use of metals [2,3]. The superior properties are demonstrated by brakes based on CMC for example, which have very low wear rates and enables brakes that endure the entire service life of different applications [4], and with an appropriate remanufacturing (refurbishment) even a second or third life gets feasible (rebrake [5]. However, the production of CMC applications has a huge energy demand and depending on the CMC type, considerable volumes of high-grade silicon and ceramic or carbon fibers, which are very expensive and which are produced with a high amount of energy, are required. Preliminary life cycle assessment (LCA) results on environmental impactsCeramic Matrix Composites (CMC) are light weight materials with high specific strength, a high temperature resistance, and high resistance to corrosive environments [1]. Ceramic fibers embedded in a ceramic matrix thereby overcome the disadvantages of conventional technical ceramics and allow applications that go beyond the possible use of metals [2,3]. The superior properties are demonstrated by brakes based on CMC for example, which have very low wear rates and enables brakes that endure the entire service life of different applications [4], and with an appropriate remanufacturing (refurbishment) even a second or third life gets feasible (rebrake [5]. However, the production of CMC applications has a huge energy demand and depending on the CMC type, considerable volumes of high-grade silicon and ceramic or carbon fibers, which are very expensive and which are produced with a high amount of energy, are required. Preliminary life cycle assessment (LCA) results on environmental impacts of the CMC production indicate high environmental impacts in its production phase [2]. Obviously, there is a strong need to evaluate processing of CMC in the future in order to define a suitable tradeoff between properties and reduced environmental impact. Furthermore, this gives rise to the need of using CMCs as efficiently as possible and to close loops in the different life-cycle stages. The circular use of products and materials provides the opportunity to partially offset the high environmental impacts of the production phase [6,7]. The production volumes of ceramic matrix composites are still low compared to other material classes, however the annually produced volumes are steadily increasing in recent years [2]. As production volumes grow, with a certain delay increasing material volumes will reach their end-of-life, making the issue of circularity increasingly important.
This paper gives a brief overview on the current scientific discussion on the circular use options of CMCs. Chapter 2 gives a state of the literature by introducing methods for the assessment of material circularity in general and a literature review on the circular economy efforts of CMCs. In chapter 3 concludes and discusses the findings of the literature review and gives an outlook on relevant research topics.…
