Field assisted sintering of electro-conductive ZrO2-based composites

In order to reveal the fundamentals of the field assisted sintering technique (FAST), also known as spark plasma sintering (SPS), the evolution of the current density and temperature distribution in the punch-die-sample set-up during FAST of ZrO2–TiN powder mixtures was modeled by finite element calculations supported by in situ measured electrical and thermal input data. The thermal and electrical properties of partially sintered composite powder compacts were estimated using theoretical mixture rules, allowing to calculate the current density and temperature distribution inside the tool and the specimen during the FAST sintering process. The electrical properties of the sintering composite powder compact, and hence the thermal distribution in the sinter set-up, changed drastically during densification once percolation occurred. Based on the calculated thermal distribution inside the composite powder compact, an optimal tool-powder compact design was determined in order to process electrically conductive ZrO2–TiN composites from electrical insulating powder compacts within minutes with high reproducibility.