Ultra-Thin, 3-D Ceramic Matrix Composite Cladding

The deployment of ceramic matrix composites (CMCs) to nuclear-related applications became acceler- ated after the 2011 Fukushima accident. In the US, this effort is administered by the Department of Energy (DOE) Office of Nuclear Energy (NE) under a Congressionally-mandated Accident-Tolerant Fuel (ATF) program. This effort still requires several technical advancements to achieve widespread use in nuclear reactor structures and fuel cladding. Silicon carbide (SiC), as part of a SiC matrix-SiC fiber system, is recognized as the primary material option to achieve the ATF goals, but present-day manufacturing presents multiple performance issues for nuclear fuel com- ponent manufacturers. These performance shortcomings include strength and thermal conductivity degradations due to manufacturing-induced damage and the environmental response of the material in nuclear environment. Free Form Fibers (FFF) proposes a novel approach to fabricate a non-woven fiber architecture for Ceramic Matrix Composites (CMCs) using its additive manufacturing-based Rapid Laser-Induced Chemical Vapor Deposition (R- LCVD) technology, which would eliminate the need for fiber weaving and also open an opportunity to create innova- tive metal matrix composite-ceramic matrix composite (MMC-CMC) hybrid structures. This non-woven design, termed micro trellises, would allow for several important technical advances needed to achieve the DOE and nuclear industry's goal for safe, high efficiency fuel designs. The non-woven architecture significantly reduces the residual porosity and increases the possible fiber volume fraction loading, while also curtailing manufacturing induced defects. These features minimize the necessary CMC component thickness, providing positive benefits to the bulk thermal conductivity, component weight reduction, and easier and quicker matrix formation via vapor infiltration. The program presented by FFF in this proposal aims to demonstrate the viability of fabricating metal-CMC hybrid cladding on the basis of micro trellis design. FFF has extensive capabilities to form SiC fiber arrays, trellis-like posts on substrates as well as coat fibers and posts with interface coating materials. FFF also introduces a novel approach to vapor infiltration of the matrix designed to minimize damage the underlying substrate to create a CMC component, or a MMC-CMC component. Component-level properties like thermal conductivity will be evaluated as well as more fundamental hydrothermal corrosion in nuclear reactor and mechanical properties of the trellis structures. The development of FFF's micro trellis will enable several needed technical advances for CMC technology, impact- ing a wide range of applications including the nuclear power, aviation, aerospace and gas turbines. One of the most significant improvements will be the reduction in overall CMC manufacturing economic costs for nuclear fuel reactor components such as cladding.