Ultra-high temperature ceramics Fahrenholtz, William G; Wuchina, Eric J; Lee, William E ...
2014., 2014, 2014-10-10, 2014-09-29
eBook
"This book will capture historic aspects and recent progress on the research and development of ultra-high temperature ceramics. This will be the first comprehensive book focused on this class of ...materials in more than 20 years. The book will review historic studies and recent progress in the field. The intent is to provide a broad overview and critical analysis rather than focus on the latest scientific results. The content will include synthesis, powder processing, densification, property measurement, and characterization of boride and carbide ceramics. Emphasis will be on materials for hypersonic aerospace applications such as wing leading edges and propulsion components for vehicles traveling faster than Mach 5, but will also include materials used in the extreme environments associated with high speed cutting tools and nuclear power generation"-- Provided by publisher. "This book provides a snapshot of the current state-of-the-art in the processing, densification, properties, and performance of boride and carbide ceramics. The book contains contributions from leading experts who have active research in ultra-high temperature ceramics"-- Provided by publisher.
The thermal conductivity, thermal expansion, Youngs Modulus, flexural strength, and brittle–plastic deformation transition temperature were determined for HfB
2, HfC
0·98, HfC
0·67, and HfN
0·92 ...ceramics. The oxidation resistance of ceramics in the ZrB
2–ZrC–SiC system was characterized as a function of composition and processing technique. The thermal conductivity of HfB
2 exceeded that of the other materials by a factor of 5 at room temperature and by a factor of 2·5 at 820°C. The transition temperature of HfC exhibited a strong stoichiometry dependence, decreasing from 2200°C for HfC
0·98 to 1100°C for HfC
0·67 ceramics. The transition temperature of HfB
2 was 1100°C. The ZrB
2/ZrC/SiC ceramics were prepared from mixtures of Zr (or ZrC), SiB
4, and C using displacement reactions. The ceramics with ZrB
2 as a predominant phase had high oxidation resistance up to 1500°C compared to pure ZrB
2 and ZrC ceramics. The ceramics with ZrB
2/SiC molar ratio of 2 (25 vol% SiC), containing little or no ZrC, were the most oxidation resistant.
Introduction Fahrenholtz, William G; Wuchina, Eric J; Lee, William E ...
Ultra‐High Temperature Ceramics,
10/2014
Book Chapter
This chapter introduces ultra‐high temperature ceramics. The first section provides background information about the conference that motivated this compilation. Next, Ultra‐High temperature ceramics ...are described and applications for these materials are listed. The chapter concludes by previewing the content of the rest of the book.
Samples of hexagonal α-Hf containing up to 30 at.% N in solid solution were made by a solid-state reaction. The brittle-to-ductile transition temperature increased as the %N increased. Steady-state ...compressive deformation has been measured from 20 to 1000 °C. The data for pure Hf could be fit using a threshold stress with a stress exponent of 5. The stress exponent of the Hf–N solid solution materials was between 5 and 8. The experiments could be interpreted on the basis of dislocation-controlled plasticity, with N acting as classical solid-solution hardening solutes. Transmission electron microscopy supported this interpretation.
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