Impact of graphite foil rolling on the thermal field homogeneity of spark plasma sintering
Résumé
Heating and thermal gradients are important parameters in Spark Plasma Sintering (SPS) affecting densification, structure and microstructure of materials. Controlling those parameters requires advanced Joule heating simulations. The key aspect of these models is the identification of the electrical and thermal contact resistances (ECR and TCR) in the SPS tooling. The latter have a high importance to explain the experimental temperature field. The ECRs and TCRs have already been determinated in a previous work by simulating the experimental thermal field. However, these previous studies consider rolled graphite foil placed between the die and punches. ECRs and TCRs have been recalibrated to consider a “no rolling graphite foil”, using SPS experiments equipped with several temperature measurements points. Those new tests shows that the previous model overestimated the temperature of the punches and sample up to 400°C when applied to a configuration with “no rolling graphite foil”. This recalibration also demonstrates it is necessary to divide the foil ECR by 2 and the TCR by 10 to obtain a predictive simulation of the thermal field. This study also shows that the use of a “no rolling graphite foil” reduces significantly the heterogeneity of thermal field.
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