Mechanical Properties of Porous, High Temperature Structural Materials: Sourcesof Toughness in Reaction Bonded Silicon Nitride

摘要

Reaction bonded silicon nitride (RBSN) prepared from submicron size pure siliconpowder is a micro-porous ceramic with excellent mechanical and dielectric properties for high temperature structural applications and for radomes. In this research program the mechanical properties including elastic moduli, tensile strength and fracture toughness of RBSN was experimentally studied in connection with its quasi-regular microstructure. The further ranges of microstructural features and the processes related to local fracture resistance were studied by means of two relate and quite flexible computer simulations of the reaction kinetics controlling the microstructure and the processes that control the crack paths. These results are summarized and presented in greater detail in four appended manuscripts.