Creep in ceramics

Creep rate in ceramics is smaller than in metals but experimental evidence indicates similar creep behavior between them. Metals and ceramics exhibit diffusion creep with n = 1 at low stresses and n ~ >3 at high stresses. Creep, both in metals and ceramics in the steady state, is diffusion controlled and the homologue temperature of T/Tm, regarding the diffusion coefficient, also applies to both materials. One of the reasons for the smaller creep rate is related to the diffusion rate, which is smaller in ceramics than in metals at the same homologue temperature. The diffusion-controlled creep rate in ceramics has a higher activation energy, Q, than in metals causing a slower creep rate. There is an advantage of using single crystal due to the absence of grain boundaries. Further, one should choose (i)materials with high melting points;(ii)the use of strongly bonded ceramics; and(iii)alloying for dislocation pinning. © 2017, Springer International Publishing AG.