High Temperature Studies of La-Monazite
Final rept. 15 Feb 2000-14 Feb 2003
ROCKWELL SCIENTIFIC CO THOUSAND OAKS CA
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This report summarizes results from a 3-year research effort aimed at gaining a basic understanding of high-temperature properties of LaPO4, with a view to its application in high-temperature structural composites. Previous studies at Rockwell and the Air Force established that LaPO4 has a unique set of properties that make it suitable as a weakly bonded interphase material that enables damage tolerance by decoupling damage in the matrix and the reinforcing fibers. However, there was previously very little information on the fundamental high temperature properties of LaPO4, such as environmental stability, sintering, grain growth, mechanical and dielectric properties. Such studies require high purity powders that have only recently been produced at Rockwell. Using these materials, measurements have been made of the following properties stability in various high temperature environments required for Air Force application, including water-containing environments typical of combustion, vacuum, and reducing environments high-temperature creep, hardness, toughness, and sliding low-temperature debonding, deformation, and sliding mechanisms and dielectric properties. A preliminary assessment is made of the potential for developing directionally solidified eutectic oxide 5 stems containing LaPO4 for toughening.
- Ceramics, Refractories and Glass
- Laminates and Composite Materials