Verdichtung elektrisch leitfähiger Composite nahe der Perkolationsschwelle

Abstract
The densification behaviour of hexagonal BN/TiB2 composites by Field Assisted Sintering Technology (FAST)/ Spark Plasma Sintering (SPS) was investigated. The investigations were carried out using shrinkage curves, mircrostructure evaluations and FE modeling. Additionally, in-situ measurements of the temperature were taken at two positions using an internal and external control pyrometer. hBN/TiB2 composite materials with a composition close to the percolation threshold show a complex sintering behaviour. They become conductive in a large range of temperature, starting at 1,300°C. An Ostwald ripening process of the
TiB2 grains cause the microstructural development at a comparatively long dwell time. So, homogeneous distributions in resistivity were obtained with a dwell time of 30 min. In comparison to traditional hot pressing processes the overall cycle time can be reduced.