High temperature creep of lithium zinc silicate glass-ceramics

The creep and recovery behaviour in compression of two lithium zinc silicate glassceramics is established over the temperature range 590 to 750° C at stresses up to 91.4 MN m−2. It is shown that the transient creep obtained is linearly viscoelastic and obeys the Boltzmann superposition principle. The activation energy of the rate-controlling process is the same as that found for secondary creep and is due to viscous flow of the residual glass phase. A simple method of analysis of the strain-time curves is presented, which can be modified to apply to stress relaxation tests.