Porous electrically conductive materials produced by Spark Plasma Sintering and hot pressing of nanodiamonds

Abstract Nanodiamond particles are known to graphitize upon annealing gradually transforming into carbon onion structures. The goal of this work was to evaluate the potential of nanodiamond powders as a raw material to produce bulk porous electrically conductive materials by means of graphitization-accompanied Spark Plasma Sintering and hot pressing. Despite consolidation that occurred in parallel to graphitization, an increase in the specific surface area (up to 510 m 2  g −1 ) relative to the nanodiamond powder (360 m 2  g −1 ) was observed in compacts with high graphitization degrees. Compacts Spark Plasma Sintered at 1200 °C and hot-pressed at 1500 °C showed high electrical conductivities, which were one order of magnitude higher than those of the powders produced by nanodiamond graphitization and only 40–50 times lower than that of bulk graphite. Based on these results, a conclusion was made that consolidation of nanodiamonds by Spark Plasma Sintering and hot pressing can be used for developing porous electrically conductive materials with tailored specific surface area. A possible influence of electric current on graphitization of nanodiamonds during Spark Plasma Sintering was suggested.