Aqueous tape casting of super-hard B4C laminates with rGO-enriched reinforcing interlayers
Cristina Ojalvo, Marcos Ayllón, Ángel L. Ortiz, Rodrigo Moreno
Abstract
Superhard B 4 C parts with microarchitectures constituted by ceramic layers and evenly-spaced rGO-enriched reinforcing interlayers were fabricated for the first time. To this end, a concentrated slurry of B 4 C with its Ti-Al sintering additive was first prepared by aqueous colloidal processing, optimizing its total solids loading and content of both binder and plasticizer to obtain, by tape casting, handleable and flexible green tapes. A semi-dilute aqueous suspension of B 4 C with Ti-Al and abundant GO was also prepared to dip-coat those green tapes with a GO-enriched layer, optimizing the withdrawal rate and the dipping time. The bare and GO-coated B 4 C+Ti-Al tapes were then sequentially laminated, thus yielding green multilayered laminates that finally were appropriately debinded and densified by spark plasma sintering. Vickers indentation tests demonstrated that these multilayered laminates are superhard (∼31 GPa), and that their rGO-enriched reinforcing interlayers are effective in arresting crack propagation.