FINAL STAGES OF SINTERING OF CERAMIC MATERIALS - EFFECT OF RESIDUAL POROSITY AND MICROSTRUCTURE ON MECHANICAL CHARACTERISTICS OF SURFACE

The final stage of sintering determines the mechanical characteristics of material. Usually the final stages of sintering are optimized via residual porosity and grain size and shape (that are believed to contr ol mechanical characteristics) with the help of temperature and time o f sintering. Elimination of residual porosity at final stage of sinter ing may be accompanied by excessive grain growth. Grain growth may tak e place as a result of secondary recrystallisation during solid state sintering. During sintering in the presence of a liquid phase, grain g rowth may be a result of ''dissolution-precipitation'' mechanism, as w ell as a result of direct coalescence owing to migration of solid-soli d boundaries. A study of the load dependence of hardness and deviation s of values of microhardness from the average value can be an instrume nt of optimization of the final stages of sintering. (C) 1997 Elsevier Science Limited and Techna S.r.l.