Impact/Erosion Resistant Environmental Barrier Coatings (EBCs) for Ceramic Matrix Composites (CMCs)

Lightweight silicon-based ceramics are leading candidates to replace heavier nickel-based superalloys for hot section components used in advanced gas turbine engines having increased specific power. Unfortunately, exposures of these materials to the high temperature combustion environments alter the effectiveness of thermally grown silica scales in providing protection from oxidation and component recession during service. Environmental barrier coatings (EBCs) are therefore required that protect the underlying ceramic substrate from environmental attack. Such coatings require good stability in the presence of water vapor, a mechanism for limiting oxygen/water vapor transport and high temperature phase stability. The nature of the silicon-based ceramic recession issue dictates that any EBC system must provide prime reliant performance to ensure full component lifetimes. To meet this goal, it is anticipated that the erosion/impact resistance of the current generation EBC coating systems will need to be enhanced. This has led to interest in advanced thermal/environmental barrier coating(T/EBC) systems having enhanced erosion / impact resistance over current state-of-the-art T/EBC systems. In this work, novel coating synthesis techniques that enable the deposition of T/EBC systems having materials, microstructures and architectures anticipated to promote coating system toughness and improved durability in environments having significant erosion/impact events are investigated.