Graphene-reinforced mechanical properties of calcium silicate scaffolds by laser sintering

Abstract

Graphene may have great potential as the reinforced phase in bioceramics by virtue of its extraordinary mechanical properties and intrinsic biocompatibility. Calcium silicate (CaSiO₃) bioceramics have been proposed as promising biomaterials but suffer from poor mechanical properties. In this study we report for the first time the use of graphene to improve the strength and toughness of CaSiO₃ bioceramics for bone scaffolds. Graphene–CaSiO₃ composite scaffolds were fabricated via selective laser sintering technology, in which the sintering time was reduced to seconds or even microseconds through the rapid heating and cooling process of a laser. The fracture morphology, chemical composition and mechanical properties of the composite scaffolds were investigated and analyzed. The results showed that graphene was octopus-like with tall and straight tentacles embedded in the bioceramic matrix, indicating a toughening mechanism of pull-out. The remaining graphene in the composite scaffolds increased logarithmically with the graphene addition. The strength and toughness firstly increased with graphene content (0–0.5 wt% in this study) which was attributed to the load transfer from the ceramic matrix to graphene when fractured, while they decreased as the graphene content further increased to 1.0 or above due to the occurrence of graphene agglomeration and holes induced by excessive graphene. There were optimal improvements of fracture toughness by 46% and compressive strength by 142%.