Interfacial bonding characteristics of in-situ synthesized graphene-coated copper nanocomposite powders using wheat flour precursor

It is quite difficult to in-situ synthesize graphene directly and economically onto surfaces of copper powders as a reinforcement phase for metal matrix composites, and few studies have been focused on interfacial bonding characteristics between graphene (Gr) layer and copper powders. This paper explores a new strategy using wheat flour as a precursor to in-situ generate graphene on the surfaces of copper powders and investigates interfacial bonding characteristics between Gr and copper powders. Results reveal that the in-situ generation process of graphene on the surfaces of copper powders has two critical stages. The first one is the low-temperature stage (up to 400 ℃), in which H2 reduces the oxide layer (Cu2O) into metallic Cu on the surfaces of the copper powders. The second one is the high-temperature stage (from 289 to 800 ℃), in which the copper powders, with their good catalytic properties, cause the break-up of chemical bonds of the flour and expose the carbon atoms, and then high affinity of copper and carbon atoms causes recombination of carbon atoms and formation of graphene. Interfacial structures of the graphene-coated copper composite powder show semi-coherent features with a lattice matching of Gr{002}//Cu{111}. The interfaces between Cu and Gr have not shown any intermediate phases or porous structures. These composite powders produced using such a low-cost but highly efficient process can be effectively used as an excellent reinforcement for metal matrix composites.