Abstract :
All sintering techniques have their advantages and disadvantages. In this contribution it will be shown that the SPS technique is very well suited for the task to prepare nano-structured ceramics. In this contribution the processing strategy used to obtain nano-sized ceramics of Bi4Ti3O12, BaTiO3, and SrTiO3, respectively, will be discussed in some detail and outline the procedure that allow us to define a “kinetic window” within which it is possible to densify these nano-powders into fully dense compacts containing grains of almost the same size as the staring powders. We have up to day consolidated some 20 different of nano-sized powders into fully dense compacts having grain sizes exceeding those of the starting powders by factors ranging from 1.5 to 6. The grain growth factor varies with the grain size of the starting powder, i. e. if the starting powder has a grain size in the range 60–100 nm the obtained compacts normally have grain sizes in the range of 150–250 nm. With decreasing grain size of the starting powder, e. g. 10–30 nm, the grain growth factor is increasing from 1.5–2.5 to 4–6. These observations are in line with the common knowledge that the driving force for reduction of the interfacial area is much smaller for 100 nm sized precursor powders than for 10 nm ones.
