Joining of thermoelectric material with metallic electrode using Spark Plasma Sintering (SPS) technique

One of the most important challenges faced while producing elements of a thermoelectric module (TEM) is the development of an appropriate joining technology affecting the performance of the whole thermoelectric generator. The produced joints must be characterized not only by high electrical conductivity, high heat conductivity and good adhesion, but also proper mechanical strength and, due to the working conditions, good chemical and temperature stability. This work presents lead-free junctions between a skutterudite material (CoSb3) and a metallic electrode for middle-temperature range applications. The production process and the properties of the obtained junctions are described. The materials were joined by the resistance soldering technique using the Spark Plasma Sintering (SPS) apparatus. The properties of the samples, including their electrical conductivity and Seebeck coefficient were determined and presented. Scanning electron microscopy (SEM) was used to investigate the microstructure, whereas electron dispersive spectroscopy (EDS) was employed to analyze the distribution of the elements. The research was aimed at examining the progress of diffusion between the bounded surfaces. The obtained junction was characterized by a very low resistivity. This work summarizes the properties of the produced junctions and the possibility of their application.