Numerical simulation of heat transfer during spark plasma sintering of zirconium diboride

Temperature and electric current distributions in the spark plasma sintering process of a ZrB₂ sample were simulated using finite element method. The main source of heating in spark plasma sintering is perceived as the Joule heating effect, which is a result of electric current distribution in the setup. Two sets of governing equations including the electric charge and energy conversion are utilized to obtain the temperature distribution. The acquired results for the sintering process were compared with Al₂O₃ sintered counterpart propounding two different mechanisms of heating proceeding. Al₂O₃ is an electrical insulator; therefore, the operating electric current concentrates in the graphite die close to the sample, whereas the ZrB₂ is an electric conductor resulting in a more uniform current distribution. In the non–conductive sample, heat is generally generated in the graphite die and conducted to the sample. Both Joule heating effect and thermal conduction from the die to the sample are involved in the sintering of ZrB₂. The temperature distribution in electric resistant materials is more uniform than electric conductor cases. This is attributed to the different dominant heating mechanism of materials.