The impulse excitation technique and its use for monitoring sintering processes Available to Purchase

The impulse excitation technique (IET) is a convenient and versatile tool for characterizing the elastic and so-called “anelastic” (damping) response of ceramics and other brittle materials. In particular, when high-temperature IET equipment is used, the temperature dependence of Young’s modulus (and damping) can be determined during heating and cooling. Moreover, when presintered powder compacts are used, the IET can be applied to monitor changes of the material response not only with temperature itself, but also with the evolution of the microstructure, as soon as the original sintering temperature is exceeded. In this paper we explain this approach and give two instructive real-world examples, viz. sintering of a hydroxyapatite-alumina composite and a pure tin oxide ceramic. While in the first case the increase of Young’s modulus is essentially due to densification, in the second case this increase is entirely due to geometric and topological changes in the microstructure that are not accompanied by densification and shrinkage.