SPARK PLASMA SINTERING (SPS) FACILITY

The Spark Plasma Sintering (SPS) facility was established in 2008 at Department of Materials and Metallurgical Engineering with financial contribution from Department of Science and Technology and CARE grants of IIT Kanpur. It enables superfast consolidation to make dense ceramics, metals and powder metallurgical materials and is the second one in our country. The facility (Figure 1) is currently installed in the Laboratory for Biomaterials. Unique features: SPS is one of the variants of the Field Activated Sintering Technique (FAST). FAST involves the imposition of an electrical field during sintering. A large current (up to 6 kA) is made to flow through a porous powder compact, contained in a graphite die-punch assembly (see Figure 2). This enables to attain high heating rate of up to 600oC/min, depending on die size. Typically, holding time of 5-10 minutes at sintering temperature is sufficient to densify the materials in the SPS process and the total processing time is less than one hour. Applications: In view of faster heating rate and shorter holding time, SPS is capable of producing nanostructured ceramics as well as nanocomposites and importantly, SPS has the potential to restrict sintering reactions in highly reactive systems. In order to illustrate this, Transmission Electron Microscope (TEM) images of the spark plasma sintered yttria stabilised ZrO ceramic (Figure 3) and WC-ZrO nanoceramic composite (Figure 4) are shown. In both the cases, nanosized equiaxed Zirconia gains can be clearly seen.