Due to their high temperature capability, low density, high stiffness, and corrosion resistance, advanced structural ceramics are enabling materials for new transportation engine systems that have the potential for significantly reducing energy consumption and pollution in automobiles and heavy vehicles. Currently, ceramics are used in limited production applications for cam rollers and injector plungers, and in the form of coatings applied to cylinder head fire decks and pistons. In the early 1980's the U.S. Department of Energy (DOE) Office of Transportation Technologies (OTT) and U.S. Industry accelerated activity in the development of ceramics for advanced heat engines. DOE's Ceramic Technology Project (CTP) at Oak Ridge National Laboratory (ORNL) was a major program that demonstrated the performance and reliability of advanced ceramics for heat engines including automotive gas turbine and heavy-duty diesel engines. In a major CTP program initiative, Norton Company's Northboro R&D Center (now a division of Saint-Gobain Industrial Ceramics, Inc.) successfully completed an Advanced Process contract demonstrating reliable and high-tensile-strength ceramics. The Processing program approach was to implement in-process inspection, nondestructive evaluation, statistical process control, mechanical characterization, and proof testing in the production of tensile specimens by both injection molding and pressure slip casting. Utilizing a new closed-loop aqueous process and systematic flaw reduction methodologies, the program achieved 1 GP-a tensile strengths and high Weibull moduls in high temperature silicon nitride, thereby demonstrating that advanced ceramics can be viable propulsion system materials.
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