Spark Plasma Sintering (SPS) Method, Systems, and Applications

Since two decades ago, Spark Plasma Sintering (SPS) method is of great interest to the powder and powder metallurgy industry and material researchers of academia for both product manufacturing and advanced material research and development. A rapid sintering is one of remarkable advantage of SPS. The SPS also features to provide a microstructure controlled sintering. Structurally tailoring effect in SPS processing was verified in the consolidation of nano-alumina. Therefore, it is generally well known that the SPS is an advanced processing technology to produce a homogenous highly dense nano-structural sintered compact, Functionally Graded Materials (FGM), fine ceramics, composite materials, new wear-resistant materials, thermo-electric semiconductors and Bio materials. It is considered that the ON-OFF DC pulse energizing method generates; (1)spark plasma, (2)spark impact pressure, (3)Joule heating, and (4)an electrical field diffusion effect. In the SPS process, the powder particle surfaces are more easily purified and activated than in conventional electrical sintering processes and material transfers at both the micro and macro levels are promoted, so a high-quality sintered compact is obtained at a lower temperature and in a shorter time than with conventional processes. This technique was originally invented in Japan as “Spark Sintering (SS)” in 1962. Today, a number of SPSed products for different industries are now being realized in Japan. The application has been getting into the practical industry use product stage through the scientific academia and/or R&D proto-type materials level such as in the field of mold and dies industry, cutting tools industry, electronics industry and automotive industry. It is a novel sintering process featuring energy saving and high speed consolidation and has a low power consumption of between 1/5 and 1/3 that of conventional sintering techniques such as pressureless sintering (PLS), hot press (HP) sintering and hot isostatic pressing (HIP).