Al Alloy Nanocomposite Reinforced with Physically Functionalized Carbon Nanotubes Synthesized via Spark Plasma Sintering

Abstract

Nanocrystalline Al-11.5Si (in wt%) powders were prepared by high energy ball milling of microcrystalline Al-Si powders, which were subsequently mixed with pristine and physically functionalized multi walled carbon Nanotubes (MWCNTs) separately and were consolidated by spark plasma sintering. Improvement in MWCNT dispersion was observed as a result of functionalization which resulted in improved densification of the nanocomposites. Scanning electron microscopy was performed to understand agglomeration and dispersion of CNTs. Distribution of MWCNTs, the dislocation activity and the effect of primary Si particles in nanocomposite matrix were studied by carrying out transmission electron microscopy. Nanoindentation was performed to measure elastic modulus and microhardness of the nanocomposites which showed appreciable improvement for functionalized MWCNT reinforced nanocomposite.

Tribological Behavior of Carbon-Based Nanomaterial-Reinforced Nickel Metal Matrix Composites

“…Furthermore, the quality of the microstructure also considerably affects the wear resistance of the composites [19,33,34]. Previously, several studies were conducted to utilize ball milling to obtain composite powder and followed by consolidation via the spark plasma sintering (SPS) technique to fabricate metal matrix nanocomposites reinforced with CNTs/GNPs [10,[35][36][37]. Spark plasma sintering allows consolidation of the composite powder at a relatively low temperature compared to other sintering techniques.…”

Spark Plasma Sintering and Characterization of Al-TiB2 Composites

“…Ceramic particles have high strength, hardness, low thermal expansion, and high chemical resistance. Reinforcements like ZrSiO 4 , B 4 C, TiB 2 , and SiC are used to ameliorate the hardness and wear resistance of MMCs without considerably changing the density of the material [9][10][11][12][13][14][15][16]. Among these, TiB 2 has emerged as a good reinforcement due to its outstanding features such as thermal stability, oxidation resistance, high melting point (3225 • C), and exceptional hardness (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) Vickers at room temperature).…”

Effective functionalisation of carbon nanotubes for reinforcement application in liquid state processed aluminium composites: A relatively greener approach

“…Carbon nanotubes (CNTs) are the one dimensional fibrous allotropes of carbon, discovered by Iijima in the year 1991, [1][2][3] which have drawn the focus of researchers because of their unique set of properties arising from the strong sp 2 near planner hybridisation of C-C bond. 4,5 Versatile application paradigm of CNTs includes electronics, structural composites, medicines, automotive industries and energy storage media, 3,[6][7][8] due to their high aspect ratio 9,10 and outstanding properties, 11,12 like low density (1.3 g/cm 3 ), 13 high elastic modulus (around 1.8 TPa), 14 high tensile strength (up to 300 GPa), 8 high bending strength, 15 exceptional thermo-oxidative stability, 16 low co-efficient of thermal expansion (CTE ¼ 0) 17 and high electrical conductivity. 18 Presently many material scientists emphasise to use CNTs as reinforcements in aluminium matrix composites (AMCs), as the CNTs improve their hardness, strength, toughness, resistance to creep and wear remarkably.…”

“…26 When incorporated to molten metal, a weak interface is generated due to low degree of physical interaction that reduces the strengthening effect (load transfer strengthening) of CNTs. 14,16 In order to minimize such issues and to enhance the compatibility of CNTs with the host matrix, surface modification of CNTs by various methods has proved quiet beneficial in past few years. 24,27,28 Among such surface modification methods, wet chemical oxidation in presence of an acidic media has been adopted widely due to its faster rate kinetics of oxidation, selective oxidation flexibility and surface activation by various oxygen containing groups like (-OH, C¼O, COOH).…”

“…26 When incorporated to molten metal, a weak interface is generated due to low degree of physical interaction that reduces the strengthening effect (load transfer strengthening) of CNTs. 14,16…”