Accession Number : ADA425288


Title :   High Temperature Studies of La-Monazite


Descriptive Note : Final rept. 15 Feb 2000-14 Feb 2003


Corporate Author : ROCKWELL SCIENTIFIC CO THOUSAND OAKS CA


Personal Author(s) : Marshall, David ; Davis, Janet B


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a425288.pdf


Report Date : Jul 2004


Pagination or Media Count : 103


Abstract : 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.


Descriptors :   *COMPOSITE MATERIALS , PLASTIC DEFORMATION , HIGH TEMPERATURE , CRACKING(FRACTURING) , SINGLE CRYSTALS , STRAIN(MECHANICS) , CERAMIC MATERIALS , DIELECTRIC PROPERTIES , OXIDES , BONDED JOINTS , DECOUPLING , GRAIN GROWTH , REINFORCING MATERIALS , EUTECTICS , DAMAGE TOLERANCE


Subject Categories : Ceramics, Refractories and Glass
      Laminates and Composite Materials


Distribution Statement : APPROVED FOR PUBLIC RELEASE