H.G. Prashantha Kumar

Encapsulation and microwave hybrid processing of Al 6061–Graphene–SiC composites

ABSTRACTThe demand for new aluminum alloy–based metal matrix composites with combinations of novel reinforcements, processed through innovative methods are very much needed for critical engineering applications. With this perspective, the current research work is aimed at the development of Al 6061 composites reinforced with two-dimensional Graphene nanoflake-encapsulated SiC. Ultrasonic liquid processing method is used to disperse the Graphene flake and the mixture is ball milled by adding SiC to achieve the encapsulation. Subsequently, the Al 6061 powder is added to the milled mixture and consolidated through uniaxial vacuum hot press followed by microwave hybrid sintering. Scanning electron microscope (SEM) analysis, X-ray diffraction analysis, hardness, density, and microstructure analysis were carried out on developed composites. Raman analysis was carried out to analyze the distortion on Graphene physical structure during various processing stages. Further, effects on novel combination of material w...ABSTRACT The demand for new aluminum alloy–based metal matrix composites with combinations of novel reinforcements, processed through innovative methods are very much needed for critical engineering applications. With this perspective, the current research work is aimed at the development of Al 6061 composites reinforced with two-dimensional Graphene nanoflake-encapsulated SiC. Ultrasonic liquid processing method is used to disperse the Graphene flake and the mixture is ball milled by adding SiC to achieve the encapsulation. Subsequently, the Al 6061 powder is added to the milled mixture and consolidated through uniaxial vacuum hot press followed by microwave hybrid sintering. Scanning electron microscope (SEM) analysis, X-ray diffraction analysis, hardness, density, and microstructure analysis were carried out on developed composites. Raman analysis was carried out to analyze the distortion on Graphene physical structure during various processing stages. Further, effects on novel combination of material with combined processing approach on flexural and tribological behavior have been analyzed.

Effect of graphene addition and tribological performance of Al 6061/graphene flake composite

Abstract Graphene, no wonder has attracted a significant research interest due to its extensive physical properties at its single atomic thickness and 2D morphology. The current studies focus on the role of graphene in reducing the wear and frictional coefficient of Al 6061–graphene-reinforced metal–matrix composites (MMC’s). Reinforcement chosen is 0.3, 0.6 and 0.9 wt% of graphene to investigate the self-lubricating property under dry wear condition and processed through the ultrasonic liquid processor. The dry frictional wear test was carried out using pin-on-disc tribometer to evaluate the effect of graphene content in the composites under various normal load (5, 10, 15 N) and disc sliding speed (0.4, 0.8, 1.2 m/s) conditions. The results show that there is a significant increase in the hardness and wear resistance and a reduction in the coefficient of friction (μ) values compared to pure alloys. Arithmetic mean surface roughness values (Ra), max profile peak (Rp) and max valley depth (Rv) are found to be comparatively lower than the pure alloy. Due to the tribological potential coupled with improved strength and surface roughness values, Al 6061–graphene composite are excellent candidates for all applications where it is subjected to Friction and wear.

Ultrasonication and microwave processing of aluminum alloy- Graphene - Al2O3 nanocomposite

ABSTRACT Nanocomposites with Graphene and Al2O3 (particulates) as reinforcement combinations with various proportions (weight percentage) in aluminum alloy AA 2024 and AA 2219 matrix with 30 to 40 µm are processed through vacuum hot press and microwave processing approach. X-ray diffraction and Raman spectroscopy analysis was done on developed nanocomposites to study the Graphene peaks, carbide formation, and other deformation on added Graphene in the nanocomposites during microwave processing. Microstructural, compressive, and diametrical tensile strength analyses were also carried out on developed composites. Effect of Graphene addition in combination with Al2O3, on strengthening mechanism during microwave sintering, had been discussed.

Tribological Aspects of Graphene-Aluminum Nanocomposites

Graphene is a new class of material in carbon group with strong sp—hybridized 2D-sheet like nanomaterial. In order to make an effective utilization of their astounding properties, they are currently used in the form of reinforcements in various proportions in metals and its alloys to fabricate the nanocomposites. Graphene is incorporated in oil and grease at nano range that results in higher load-carrying capacity compared with that of raw grease and oils without additives, which shows that graphene possesses self-lubricating capacity. Graphene is a planar sheet-like structure (2D), with more contact surface area in the developed composites that can make them suitable for industrial applications with well-established tribological performance. The novelty of this work focuses on the role of graphene addition in enhancing the wear performance aluminum composites to replace the conventional materials by graphene composite combinations. The current chapter explains the processing and tribological performance of graphene-aluminum composites and its effect with various hybrid combinations of MWCNT/SiC/Al 2 O 3 . Dispersion of graphene is carried out through ultrasonic liquid processor followed by ball-milling aluminum powder. Thus prepared precursors are vacuum-pressed and microwave-sintered. Graphene in the nanocomposites has resulted in significantly improving the tribological properties, where it gives the wear resistance by creating a solid, lubricant layer between the sliding surfaces.

Synthesis and characterization of AA 6061- Graphene - SiC hybrid nanocomposites processed through microwave sintering

As one of the most essential industrial and engineering materials, Aluminum alloy 6061 have been extensively used in automobile industries and many engineering applications due to its impending properties like low density, good structural rigidity, feasibility to incorporate and enhance the strength by addition of various reinforcing materials. The essential criteria in enhancing the properties without sacrificing the ductility is always challenging in Aluminum and its alloys based composites. In the recent years, enormous research has been carried on ceramic based and carbon based reinforcement materials used in Aluminum metal matrix composites. But the combination of both is never tried so far due to lack of processing methods. The current research work is carried out to process, synthesize and perform the characterization of Al 6061 matrix nanocomposites with Graphene of flake size 10 μm and SiC of particle size 10 pm as reinforcement combinations in various proportions (weight percentage) which are carried out through powder metallurgy (PM) approach. The powders are processed through ultrasonic liquid processing method and the mixtures were ball milled by adding SiC particles followed by uniaxial hot compaction. Thus prepared compacts are sintered (conventional and microwave) and mechanical properties like hardness, density are investigated as a function of Graphene and SiC concentrations (weight fraction). Relevant strengthening mechanism involved in the Al6061 - Graphene -SiC composites in comparison with monolithic Al 6061 alloy were discussed.