Hydrogen defects in alpha-Al2O3 and water weakening of sapphire and alumina ceramics between 600 and 1000 degrees C - I. - Infrared characterization of defects Academic Article uri icon

abstract

  • Hydrogen impurities in materials influence their properties, including flow strength. -Al2O3 single crystals and polycrystalline ceramics were annealed in supercritical water between 850 and 1025C, under pressures in the range 1500-2000 MPa. A few specimens were further subjected to plastic deformation. Hydrogen penetration was examined using infrared absorption measurements of O-H bond vibrations, which revealed two kinds of hydrogen defects. In single crystals, defects are characterized by sharp O-H absorption bands assigned to interstitial protons. Hydrogen impurities of hydrothermally annealed ceramics and of all hydrothermally deformed specimens are characterized by broad O-H bands assigned to molecular water. The grain boundaries of hydrothermally annealed ceramics are severely damaged. The kinetics of hydrogen penetration is consistent with diffusion data.

published proceedings

  • ACTA MATERIALIA

author list (cited authors)

  • Kronenberg, A. K., Castaing, J., Mitchell, T. E., & Kirby, S. H.

citation count

  • 39

complete list of authors

  • Kronenberg, AK||Castaing, J||Mitchell, TE||Kirby, SH

publication date

  • April 2000