Sintering, sinterforging and explosive compaction to densify the dual phase nanocomposite system Y2O3-doped ZrO2 and RuO2

Yttria-doped zirconia/ruthenia powders were made by co-precipitation. The calcined powders were compacted into green compacts using standard pressing techniques such as isostatical compaction compared to explosive compaction. Explosive compaction (EC) led to the highest density, but also to cracking of the compacts. The zirconia/ruthenia powders compacted by isostatical pressing could not be densified by pressureless sintering (58%), but sinterforging these green compacts led to dense compacts (96%), which showed large-scale phase separation between the yttria-doped zirconia and ruthenia phase. The explosively densified green compacts could be further densified to 92% by pressureless sintering, without the occurrence of the large-scale phase separation that took place within the isostatically pressed (IP) and sinterforged (SF) samples. The microstructure of the explosively densified composites was more fine-grained and homogeneous. Thus, by tuning the green density of yttria-doped zirconia/ruthenia compacts the phase separation after sintering can be tuned. This phase separation largely determines the electrical properties of these materials, which means that these electrical properties will be tunable as well.