Field Assisted Hybrid Spark Plasma Sintering Technology: a new infrastructure at ISTEC-CNR to produce 'hard-to-sinter' multifunctional materials

Spark plasma sintering (SPS) is an advanced sintering technique using electric current, mechanical pressure in an atmosphere/vacuum apparatus for densification of traditional or advanced materials in one step. Raw powders or mixtures, regard-less of whether they are electrical insulating or conducting, are placed in a predesigned die before sintering. The SPS system applies uniaxial pressure and electric current to consolidate loose powders or a cold-formed compact with the desired shape. This special machine allows a homogeneous volume heating by means of the Joule effect, with high heating rates, 10-100 times higher than conventional systems, minimizing the grain growth. A wide range of material types can be consolidated, including metals, alloys and intermetallics and ceramics such as borides, carbides, nitrides, silicides and oxides, plus all imaginable composites and special material systems. SPS is the best densification technique for nanocomposites or composites containing nanoparticles and nanophases (graphene, CNT, etc.) due to lower temperature and shorter sintering times. Amongst the others, functionally graded materials and high entropy alloys are successfully fabricated with a minimum heat waste compared to other sintering techniques.