, et al.. Contact resistances in spark plasma sintering: From in-situ and ex-situ determinations to an extended model for the scale up of the process. Journal of the European Ceramic Society, Elsevier, 2017, vol. 37 (n°4) b s t r a c tHeating in spark plasma sintering is a key point of this manufacturing process that requires advanced simulation to predict the thermal gradients present during the process and adjust them. Electric and thermal contact resistances have a prominent role in these gradients. Their determination is difficult as they vary with pressure and temperature. A calibration method is used to determine all of the contact resistances present within tools of different sizes. Ex situ measurements were also performed to validate the results of the in-situ calibrations. An extended predictive and scalable contacts model was developed and reveals the great importance and diversity of the contact resistances responsible for the general heating of the column and high thermal gradients between the parts. The ex/in situ comparison highlights a high lateral thermal contact resistance and the presence of a possible phenomenon of electric current facilitation across the lateral interface for the high temperatures.

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In this paper, the problem of transient heat transfer in sliding contact is studied analytically and numerically.The heat source is represented as a uniform heat strip moving over a half-space with and without cooling outside the contact zone. The finite element method, implemented using a commercial code, was used in numerically solving this problem. An analytical solution taken from the literature was adapted to obtain the presented model and used to check the capabilities of the commercial code. After the validation of the resolution method, the work was completed by studying the influence of the Peclet number (source speed) and the Biot number (presence of cooling) on the temporal and spatial evolution of the surface temperature of the half-space. Finally, the transient constriction function is estimated and analyzed for the presented test cases. Correlations were also derived to (i) evaluate the time interval within which the steady state is reached, and (ii) estimate the constriction parameter as a function of Peclet and Biot numbers in the steady state case.

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