Localized Overheating Phenomena and Optimization of Spark-Plasma Sintering Tooling Design

Abstract

The present paper shows the application of a three-dimensional coupled electrical, thermal, mechanical finite element macro-scale modeling framework of Spark Plasma Sintering (SPS) to an actual problem of SPS tooling overheating, encountered during SPS experimentation. The overheating phenomenon is analyzed by varying the geometry of the tooling that exhibits the problem, namely by modeling various tooling configurations involving sequences of disk-shape spacers with step-wise increasing radii. The analysis is conducted by means of finite element simulations, intended to obtain temperature spatial distributions in the graphite press-forms, including punches, dies, and spacers; to identify the temperature peaks and their respective timing, and to propose a more suitable SPS tooling configuration with the avoidance of the overheating as a final aim. Electric currents-based Joule heating, heat transfer, mechanical conditions, and densification are imbedded in the model, utilizing the finite-element software COMSOL™, which possesses a distinguishing ability of coupling multiple physics. Thereby the implementation of a finite element method applicable to a broad range of SPS procedures is carried out, together with the more specific optimization of the SPS tooling design when dealing with excessive heating phenomena.

Contact resistances in spark plasma sintering: From in-situ and ex-situ determinations to an extended model for the scale up of the process

“…When needed, the ECR and TCR have been calculated using the tools dimensions and temperatures data. The order of magnitude of the ECR in horizontal/vertical directions and horizontal TCR is in accordance with [6,[10][11][12]16,17,22,24,25]. However the vertical TCR is a bit higher in our case (5.00E-03 m 2 K/W instead of about 5 E-04 m 2 K/W for [10,11,22,25] and 1.14E-03 m 2 K/W for [16]).…”

“…The equivalent thermal conductivity of the anisotropic interfacial layer in the normal and plane directions ( x , y ) are given by Eq. (22).…”

Field assisted sintering technology. Part I: Experiments, constitutive modeling and parameter identification

“…In this work the influence of four different tool sizes and various temperature regimes on the grain growth and the densification behavior is studied. In [11] the model is used to optimize the tool geometry to avoid overheating in the sample. In [12], see also [13], the strain-rate tensor is additively decomposed into an plastic, diffusion part under load as well as a diffusion part by electro-migration and by surface tension.…”

Spark plasma sintering and complex shapes: The deformed interfaces approach

“…The main difficulty of the multiple parts configurations is the temperature homogeneity. Finite Element Method (FEM) simulations of the Joule heating [12][13][14][15][16][17][18][19][20][21][22] and the densification [23][24][25][26][27][28][29][30] are performed by many authors, with the aim of predicting the temperature and densification field and find optimized solutions [10,[31][32][33][34][35][36]. In previous work [11], we showed that a homogenization of the temperature field can be attained for multiple parts configurations by adjusting the electric current flow with electric insulations and specific geometrical tricks.…”