Dual composite (DC) architectures have been shown to increase wear resistance while maintaining or increasing fracture toughness in WC-Co composites for room-temperature applications by the use of multiple, discretely segregated engineered microstructures. Composites of zirconium diboride (ZrB2) and molybdenum disilicide (MoSi2) are candidates for similar dual composite architectures for high-temperature structural use in corrosive environments, due to the high-temperature ductility and oxidation resistance of MoSi2. Additions of silicon carbide (SiC) can resolve issues of thermal expansion mismatch in ZrB2-MoSi2 DC architectures. After systematically measuring the mechanical properties of individual ZrB2-MoSi2 subcomposites at both room temperature and at 1500°C in air, multiple DC architectures were prepared by synthesizing discrete granules of a subcomposite composition and dispersing them in a continuous matrix of another subcomposite composition with different properties. This research investigates the effects of differing mechanical properties of granule and matrix subcomposites, differing oxidation resistance of the two compositions, as well as incorporation of a weak BN-based granule coating to aid in crack deflection. Mechanical properties including flexure strength and fracture toughness at room temperature and at 1500°C in air of various DC architectures will be reported and compared to corresponding traditional particulate subcomposites.
Performance Optimization of ZrB2-MoSi2-SiC Dual-Scale Composite Architectures for High Temperature Structural Applications
2017
Abstract
Dual composite (DC) architectures have been shown to increase wear resistance while maintaining or increasing fracture toughness in WC-Co composites for room-temperature applications by the use of multiple, discretely segregated engineered microstructures. Composites of zirconium diboride (ZrB2) and molybdenum disilicide (MoSi2) are candidates for similar dual composite architectures for high-temperature structural use in corrosive environments, due to the high-temperature ductility and oxidation resistance of MoSi2. Additions of silicon carbide (SiC) can resolve issues of thermal expansion mismatch in ZrB2-MoSi2 DC architectures. After systematically measuring the mechanical properties of individual ZrB2-MoSi2 subcomposites at both room temperature and at 1500°C in air, multiple DC architectures were prepared by synthesizing discrete granules of a subcomposite composition and dispersing them in a continuous matrix of another subcomposite composition with different properties. This research investigates the effects of differing mechanical properties of granule and matrix subcomposites, differing oxidation resistance of the two compositions, as well as incorporation of a weak BN-based granule coating to aid in crack deflection. Mechanical properties including flexure strength and fracture toughness at room temperature and at 1500°C in air of various DC architectures will be reported and compared to corresponding traditional particulate subcomposites.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
