Temperature distribution at steady state under constant current discharge in spark sintering process of Ti and Al2O3 powders

Obtaining the distribution of the voltage and temperature of the punch–die–compact systems in the spark sintering process is useful for generalization of its process control. The temperatures of these systems using two kinds of powders, titanium and alumina, of a conductor and an insulator, respectively, are measured by thermocouples in the constant current discharging process. The steady state showing the constant values of temperature and relative density is achieved in this process, and the measured temperature distribution in the systems is changed depending on the kind of compacts. The voltage and temperature of the systems at the steady state are also calculated on the basis of Ohm’s and Fourier’s laws. The calculated voltage distribution or current flow in the punch and die for the titanium compact system is similar to that for the alumina compact system, although there is the minor difference of the voltage distribution between titanium and alumina compacts because of the difference in the specific resistivity of compacts. The calculated temperature distribution is changed in these systems depending on the kind of compacts, because of the difference in the amount of Joule’s heat of compacts, which agrees with the temperature distribution measured by thermocouples. It is found from the result obtained in this study that distributions in voltage and temperature can be estimated by this calculation method, regardless of a kind and shape of the punches, dies and compacts.