Densification and mechanical strengthening of binderless graphite compacts via cold sintering of electroless copper coated powders

Copper decorated spherical graphite powders containing rhombohedral phase when compacted at 100 °C and 620 MPa was able to densify to ∼97.5 % relative density and demonstrated ∼50 % improvement in transverse rupture strength. In this paper, we describe Cold sintering of bulk graphite powders as a binder less densification and strengthening process, that was achieved via pressure assisted sintering of copper nanoparticles decorating graphite at particle interfaces at a modest temperature of ∼100 °C. Iron-induced electroless deposition of copper nanoparticles on bulk graphite powders were done using cementation technique. Compaction of the modified graphite powders into a highly dense monolith resulted in a thin continuous, cohesive sub-micron copper layer around the graphite particles. Dilatometry and the study of Compressibility curves provided insights on the improved densification and plastic deformation. The role played by copper particles during Cold sintering was further illustrated using Scanning Electron Microscopy and Transmission Electron Microscopy.