Life cycle assessment of carbon ceramic matrix composite brake discs containing reclaimed prepreg scraps

Abstract

In the last years, carbon ceramic brakes are preferred to traditional cast iron ones for their lightweight, high temperature resistance, and long service life, even though their manufacturing involves the use of high temperature processes and energy-intensive materials such as carbon fibers. Within the European Life Project “CIRCE”, a novel recovery system for carbon fiber prepreg scraps was developed to reclaim high-quality carbon fibers to use as a substitute of virgin carbon fibers in different application, such as in Ceramic Matrix Composite (CMC) brakes. In order to overcome the lack of scientific literature regarding the environmental sustainability of steel and CMC brakes, in the present paper, the Life Cycle Assessment (LCA) methodology was applied to carry out a detailed analysis of the environmental impacts associated with carbon ceramic brakes realized using the reclaimed prepreg scraps. The functional unit was defined as production, use and disposal of a rear brake disc used for the deceleration of a sport car during its lifetime. Different impact indicators were considered, such as Global Warming Potential, Cumulative Energy Deman and ReCiPe midpoint categories. The results were compared to those given by the sustainability assessment of cast iron disc brakes and traditional carbon ceramic brakes. The proposed LCA is a cradle to grave analysis, as it considers all the relevant inputs and outputs of the manufacturing processes, from the raw material extraction to the materials disposal. The surface of ceramic brakes was observed using Scanning Electron Microscopy to assess the different material structures. The results show that, as far as the production is concerned, cast iron brakes are the most sustainable alternative, with impacts lower than 21% of the composite component ones. However, if a long use phase more than 200,000 km is evaluated, carbon ceramic brakes obtained by reclaimed prepreg scraps are characterized by lower environmental impacts, with impacts that are about 8% lower than those obtained by traditional carbon ceramic brakes.