Continuous fiber ceramic matrix composites (CFCCs) are currently being developed for a variety of high-temperature applications, including use in advanced heat engines. For such composites, knowledge of porosity distribution and presence of defects is important for optimizing mechanical and thermal behavior of the components. The assessment of porosity and its distribution is also necessary during composite processing to ensure component unifo4ty. To determine the thermal properties of CFCC materials, and particularly for detecting defects and nonuniformities, we have developed an infrared thermal imaging method to provide a "single-shot'' full-field measurement of thermal diffusivity distributions in large components. This method requires that the back surface of a specimen receives a thermal pulse of short duration and that the temperature of the front surface is monitored as a function of time. The system has been used to measure thermal diffusivities of several CFCC materials with known porosity or density values, including SYT.,RAMICm SiC/SiNC composite samples from Dow Corning and SiUSiC and enhanced SiC/SiC samples from DuPont Lanxide Composites, to determine the relationship of thermal diffusivity to component porosity or density.
Through work in two U.S. Department of Energy cooperative programs with industry, the confidence level for utilization of ceramic composite SiC/SiC combustor liners has risen from a prototype curiosity to serious planning and addressing of hurdles for commercialization. One of the most significant hurdles for true commercialization is affordability of the ceramic composite combustor liners. To study the manufacturing costs for CFCC liners, a study was conducted to identify cost items and relationships. This report describes the effort, identifies the high impact areas of manufacturing costs, and recommends potential approaches to reducing the manufacturing costs. [S0742-4795(00)02703-4]
Through work in two U.S. Department of Energy cooperative programs with industry, the confidence level for utilization of ceramic composite SiC/SiC combustor liners has risen from a prototype curiosity to serious planning and addressing of hurdles for commercialization. One of the most significant hurdles for true commercialization is affordability of the ceramic composite combustor liners. To study the manufacturing costs for CFCC liners, a study was conducted to identify cost items and relationships. This report describes the effort, identifies the high impact areas of manufacturing costs, and recommends potential approaches to reducing the manufacturing costs.
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