Fabrication Of Graphene Reinforced Aluminum Matrix Composites And Their Mechanical Properties

Graphene,with excellent mechanical properties and unique physical and chemical properties,has been widely concerned by researchers,especially in the field of metal matrix composites,its high tensile strength and elastic modulus,outstanding ductility,and more excellent hardness than diamonds,making it an ideal reinforcement.However,there are still some bottlenecks to be resolved in graphene reinforced aluminum matrix composites(AMCs),such as the defects in reduced graphene oxide,the tendency to re-agglomerate,damages of structural integrity and the weak interface bonding.Thus,exploring new methods to break the limitations of existing issues is of great importance for obtaining metal matrix composites with excellent comprehensive mechanical properties.In this work,graphene/Al composite was fabricated by combining the in-situ chemical vapor deposition(CVD)and powder metallurgy process.Ni nanoparticles(NPs)-decorated graphene hybrid(Ni-NPs@GNP)powders were firstly synthesized by in-situ CVD combining freeze-drying technique.Then,the Ni-NPs@GNP were dispersed into Al powder by a short time intermittent ball milling to obtain homogeneous Ni-NPs@GNP/Al composite powders,which guarantee the integrity and efficiency of graphene.The composite powders were consolidated by vacuum hot-pressing and spark plasma sintering to fabricate the bulk composites.The influence of the ratio of the precursors of Ni-NPs@GNP and CVD parameters on both quality and morphologies of graphene was investigated;the influence of powder metallurgy parameters on the structure and performance of bulk composite was explored;the effect of nickel nanoparticles on the improvement of aluminum-carbon interface was studied;the strengthening mechanism of graphene in aluminum matrix composites was discussed.The results indicate that the ratio of precursors of Ni-NPs@GNP and CVD parameters has obvious effect on the quality of graphene,and the optimal parameters of process parameters can achieve controlled preparation of in-situ graphene with excellent quality.The dispersion method of short time intermittent ball milling is to ensure the effective dispersion effect and maximize the integrity of graphene structure.Nickle nanoparticles,which are anchored on the graphene nanoplates,can combine with aluminum with a strong and clean interface,it is not only improve the wettability between aluminum and carbon,so as to achieve efficient load transfer efficiency on interface,but also ameliorate the comprehensive mechanical properties of composites.Compared with vacuum hot-pressing sintering,SPS has the characteristics of rapid forming and pulse current sintering,which makes composites have more excellent comprehensive performance result from more fine grain,larger dislocation density and more complete graphene.