Creep of MgO Containing a Dispersion of Carbon
Creep experiments on polycrystalline MgO containing a fine dispersion of carbon are reported. The samples were prepared by hot-pressing and creep was measured in four-point bending under stresses of 1000 to 5000 psi at 1000° to 1300° C. Although results for MgO creep without carbon addition are in good agreement with published reports, introducing dispersions of 0.5 to 2 vol% C into MgO modifies its creep behavior. Comparing specimens of the same grain size, the samples containing the carbon dispersion had lower creep rates than those of MgO without addition. This effect increased with increasing carbon additions. The stress exponent remained small (1 to 2) in all cases. The apparent activation energy for creep increased dramatically with the carbon additions. Possible mechanisms for the influence of this dispersion on creep are discussed briefly.