Silicon nitride (Si3N4) ceramics have been considered for various components of nuclear
power plants such as mechanical seal of reactor coolant pump (RCP), guide roller for control rod
drive mechanism (CRDM), and seal support, etc. Corrosion behavior of Si3N4 ceramics in
high-temperature and high-pressure water must be elucidated before they can be considered for
components of nuclear power plants. In this study, the corrosion behaviors of Si3N4 ceramics at
hydrothermal condition (300°C, 9.0 MPa) were investigated in pure water. The grain-boundary phase
was preferentially corroded and the corrosion reaction was controlled by the diffusion of the reactive
species and/or products through the corroded layer. Results of this study imply that the variation of
sintering aids and/or the control (e.g., crystallization) of the grain-boundary phase are necessary to
increase the corrosion resistance of Si3N4 ceramics in high-temperature water.
To obtain a dense SiCf/SiC composite by the chemical vapor infiltration (CVI) process, whisker growing before matrix filling was applied, which is called the whisker growing assisted CVI process. The whisker growing and matrix filling processes were carried out using MTS (CH3SiCl3) and H2 as source and diluent gases, respectively. Tyranno-SATM was used as a reinforced substrate.
Characterizations of SiC whisker grown during the in situ whisker growing process have been investigated. The weight gain rates with the matrix filling time and the density of composites was measured. The flexural strength with the thickness of the pyrolytic carbon (PyC) interlayers has been evaluated. b-SiC whiskers with many stacking faults were grown well in the Tyranno SATM fabrics. Tyranno-SA/SiC composite with a PyC interlayer thickness of 150 nm had a flexural strength of 610 MPa and the density of 2.71 g/cm3.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.