Pulsed Current Sintering (PCS) process possesses some problems that need to be resolved. We, therefore aims at understanding phenomena of PCS process by presenting some basic data on in situ sintering behavior of PCS. Special graphite mold equipped with thermo couple and electrodes were designed to measure the temperature, electric current and voltage inside the powder during PCS process. We apply three types of raw materials, especially for ZnO as semiconductor, Al2O3 as non-conductor and WC as good conductor. The electric current and voltage were measured for each powder during PCS process. In addition, their electric resistance properties were calculated.

Thermoelectric conversion efficiency of thermoelectric elements can be increased by using a structure combining n-type and p-type semiconductors. From the above point of view, attention was directed at ZnO as a candidate n-type semiconductor material and investigations were made. As the result, a dimensionless figure of merit ZT close to 0.28 (1073K) was obtained for specimens produced by the PCS (Pulse Current Sintering) method with addition of specified quantities of , CoO, and to ZnO. It was found that the interstitial in the ZnO restrains the grain growth and CoO acts onto the bond between grains. The influence of the inclusion of and CoO onto the sintering behavior also was investigated.

The influence of the internal current for the ZnO ceramics on the sintering behavior by pulse current sintering (PCS) method was investigated. To clear the dependence of inner current on the sintering behavior of ZnO ceramics, direct measurement of electric resistance of ZnO specimen under sintering by SPS device was carried out. It was observed that electric resistance of specimen decreases with increase in the temperature. The electric resistance begins to decrease from the low temperature of . The internal structure of sintered ZnO ceramics changed by the control of the internal current in the specimen using plate.