Temperature Measurement of the Mold and Samples on the Pluse Plasma Sintering

Abstract

The plasma activated sintering (PAS) is a kind of hot pressing method. During pressing, the electric current flows in the mold (die and punches) and powder sample. There are two types of electric current. The surface of the powder is cleaned and activated by activating electric current. The mold and powder sample is heated by sintering electric current due to the Joule effect. It is well-known that the temperature of a sample is closely related to the sintered materials' properties and there is a favored temperature for sintering the powder. The temperature is measured either by thermocouples in the mold or by an infrared optical thermometer focused on the mold surface, but these measurements do not give the temperature of the sample in the mold itself. Sometimes the real temperature of samples is higher than the measured temperature. This temperature difference depends on the material properties, especially the electric resistance and the thickness of the sample. The authors studied experimentally the relation between the temperature difference and the electric resistance using dummy samples made of stainless steel, graphite and alumina.