CREEP OF SILICON CARBIDE *

Abstract

The creep behaviour of high-density silicon carbide has been examined under four-point transverse bending in air at temperatures from 1000 to 1300°C. Stresses in the range 0·207 GN m⁻² (30 000 Ib in⁻²) to 0·496 GN m⁻² (72000 lb in⁻²) were applied.

In tests lasting up to 3·6 Msec (1000 h) the creep strain (ϵ _p ) increased with time (t) as ϵ_p = At^k where k was between 0·2 and 0·5. The dependence of A on stress (σ) and absolute temperature (T) was found to be A ∝ σ ⁿ exp(-Q/RT) with n between 1 and 2 and Q∼230 kJ mole⁻¹ (55 kcal mole⁻¹).

These results are compared with estimates of creep in SiC obtained by extrapolation of steady-state creep data from higher temperatures.