Compressive creep of polycrystalline ZrSiO4

Polycrystalline ZrSiO4 ceramics were prepared from commercial powder. Silic ate-based glass phase was observed at multiple-grain junctions. Compressive creep tests were conducted in Ar at 1197-1400 degreesC. For stresses of ap proximate to1-120 MPa. steady-stare creep occurred by diffusional flow. For stresses of > 3 MPa, the steady-state strain rate (epsilon) over dot could be expressed as (epsilon) over dot = A sigma (1.1+/-0.1) exp - [(470 +/- 40 kJ/mol)/RT]. where A is a constant, sigma the steady-state stress, R the gas constant, a nd T the absolute temperature. Al 1400 degreesC and 1 MPa, an increase in t he value of n was observed. Electron microscopy revealed no deformation-ind uced change in the microstructures of any of the specimens, which is consis tent with creep by diffusion-controlled grain-boundary sliding. Comparison with literature data indicated that volume diffusion of oxygen controlled t he creep rate. (C) 2001 Elsevier Science Ltd. All rights reserved.