Compressive creep of polycrystalline ZrSiO4

Polycrystalline ZrSiO4 ceramics were prepared from commercial powder. Silicate-based glass phase was observed at multiple-grain junctions. Compressive creep tests were conducted in Ar at 1197–1400°C. For stresses of ≈1–120 MPa, steady-state creep occurred by diffusional flow. For stresses of >3 MPa, the steady-state strain rate ε̇ could be expressed asε̇=Aσ1.1±0.1exp−470±40 kJ/mol/RT,where A is a constant, σ the steady-state stress, R the gas constant, and T the absolute temperature. At 1400°C and 1 MPa, an increase in the value of n was observed. Electron microscopy revealed no deformation-induced change in the microstructures of any of the specimens, which is consistent with creep by diffusion-controlled grain-boundary sliding. Comparison with literature data indicated that volume diffusion of oxygen controlled the creep rate.