The Effects of Surface Condition and Chemical Environment on the Deformation and Fracture Processes of Ceramic Materials

摘要

Results obtained in study of high temperature deformation of rutile (TiO2) are briefly summarized. Refined sample preparation techniques, which have resulted in a significant reduction in scatter of fracture strength data, are described. Atmosphere during surface damaging, for atmospheres of O2, N2 and A, have been found to have no detectable effect on subsequent fracture strength. Influence of impurities on fracture has been further examined; results were negative for the impurities studied. Measurements of dislocation velocities in Ge crystals below 325C are reported, at resolved shear stresses as high as 60 kg/sq. mm. No drastic departures from known behavior at higher temperatures and lower stresses were observed. The diffusion of interstitial Li in retile (TiO2) was measured over a temperature range of 80 - 360C, utilizing the optical absorption associated with the Li impurity as a measure of its concentration. Diffusion was found to be strongly anisotropic with diffusion coefficient D perpendicular to the C-axis smaller than D parallel by a factor of at least 10 to the 8th power up to 550C. Concentrations and solubility of Li in rutile were measured approximately using chemical analysis. Latice distortion and other impurities strongly inhibit Li diffusion.