Environmental impact of manufacturing and use of ceramic matrix composites for aerospace propulsion applications

Ceramic Matrix Composites (CMCs) have emerged as promising materials with exceptional mechanical properties, making them appealing for aerospace applications. Notable contenders among various CMC formulations, including Al 2 O 3 /SiO 2 , Al 2 O 3 /B4C, and SiC/SiC, show great potential for replacing traditional materials in the production of aircraft components, such as turbine blades. However, environmental evidence to support such substitution remains limited, and no consistent basis exists for comparing CMCs with established materials across their full life cycle. This paper presents a cradle-to-grave Life Cycle Assessment that compares five candidate blade materials under a common functional unit and a single blade geometry, so that differences in impact are attributable to the material and its manufacturing route. The study covers Al 2 O 3 /SiO 2 manufactured by sol-gel infiltration, Al 2 O 3 /B 4 C manufactured by sintering, and SiC/SiC manufactured by chemical vapour infiltration, pyrolysis of a preceramic polymer, or melt infiltration, alongside the nickel superalloys Inconel 625 and Hastelloy X manufactured by powder metallurgy. An aircraft turbine blade is selected as the case study, with material quantities defined from the blade design criteria and impacts assessed across the manufacturing, use, and end-of-life phases. Variation in the underlying inventory and operational assumptions is examined to test how firmly the comparison holds and which parameters drive it. The results provide a quantified basis for material and process selection in turbine blade design, identifying the life cycle stages and manufacturing parameters that govern the environmental performance of each option.