Graphene oxide and graphene nanosheet reinforced aluminium matrix composites: Powder synthesis and prepared composite characteristics

Abstract

The preparation and properties of reduced graphene oxide (rGO) and graphene nanosheets (GNSs) reinforcement of aluminium matrix nanocomposites (AMCs) are reported. For the rGO-AMCs, commercial colloidal GO was coated onto aluminium powder particles and then reduced via thermal annealing. For the GNS-AMCs, graphene exfoliated from graphite through ultrasonication and centrifugation was coated onto aluminium particle surfaces via dispersion mixing, filtering and drying. Pure aluminium and aluminium composites with various reinforcement concentrations of rGO and GNS were cold compacted into disc-shaped specimens and sintered in inert atmosphere. The mechanical properties and microstructure were studied and characterised via Vickers hardness, X-ray diffraction, density measurement, and scanning electron microscopy. The reinforcements were uniformly distributed onto the aluminium particle surfaces before and after consolidation within the composites. The relevant factors for the powder metallurgy process (compaction pressure, density, and sintering conditions) were optimised. Increased levels of increased hardness were recorded, over baseline compacted and sintered pure aluminium samples, prepared under identical experimental conditions, of 32% and 43% respectively for the 0.3wt.% rGO-Al and 0.15wt.% GNSs-Al composites. The process developed and presented herein provides encouraging results for realising rGO-AMC and GNS-AMC nanocomposites via low cost cold powder compaction and sintering metallurgy techniques.

An Overview of Metal Matrix Nanocomposites Reinforced with Graphene Nanoplatelets; Mechanical, Electrical and Thermophysical Properties

“…Several solutions have been proposed to address these issues, for instance: coating the reinforcement with an active metal to prevent the direct contact of molten Al and reinforcement [41,105,106], adding some alloying elements to increase the wettability and also prevent the reaction from the thermodynamic point of view [107][108][109]. Another solution is designing the process parameters in such a way that it would be possible to avoid the carbide formation reaction by using the powder metallurgy process to fabricate the AMCs [110]. As discussed earlier, the interfacial bonding is the other issue that should be considered in the fabrication of AMCs in order to take the advantages of the reinforcement [111].…”

Effect of Reinforcement Type and Dispersion on the Hardening of Sintered Pure Aluminium

“…% exfoliated graphene nanosheets. The preparation involved 48 h dispersal by magnetic stirring of the as-prepared graphene with Al powder, compacting at 560 MPa and sintering at 600 • C for 4 h in an Argon atmosphere [42]. The difference between these reports and the results of this study (graphene nanocomposite in Table 5) can be attributed to the dispersion methods, characteristics of the Al powder, type and volume fraction of the graphene, and the thermomechanical history of the nanocomposites.…”

Processing of Graphene/CNT-Metal Powder

“…Some of the studies used slurry blending technique in which the ethanol or acetone is used as the medium. Thus processed metal matrix and graphene mixtures are consolidated through hydraulic pressing or hot isostatic pressing (HIP) and sintered at <600°C in argon (Ar) atmosphere followed by extrusion [56].…”