In this study, aluminium-carbon nanotube-nickel (Al-CNT-Ni) composite was prepared by powder metallurgy from pure Al powder and Ni-encapsulated CNT. Previously, carbon nanotubes were coated with nickel following ultraviolet-assisted electroless deposition method. Tensile strength and hardness of the composites were found to increase in proportion to the CNTs addition. For an addition of 7 wt.% Ni-coated CNTs containing 2.5 wt.% nanotubes of 8-15 nm diameter (Ni to CNT ratio was 1-0.357), resultant tensile and yield strength were increased by 129.26% and 157.48% respectively compared to pure aluminium. Hardness was also increased by 171.39%. These results were obtained while conventional sintering was followed by further consolidation by Hot Isostatic Pressing (HIP). Enhanced mechanical properties are attributed to the well dispersion of CNTs in aluminium matrix and strong interfacial bonding between CNT and aluminium. Well dispersion of CNTs and strong interfacial bonding was resulted from the uniform Ni-encapsulation as verified by red shift in Raman Spectroscopy.
This study had been carried out to investigate the effect of micron size Ni particle addition on the microstructure, melting behavior and mechanical properties of the ternary Sn-9Zn solder alloys. Different weight percentage, viz. 0.25, 0.5 and 1 of micron size Ni particle was added in the liquid Sn-9Zn alloy and then cast into the metal mold. Melting behavior was studied by Differential Thermal Analyzer (DTA). Microstructural investigation was conducted using Optical and Scanning Electron Microscope (SEM). Tensile properties were determined at a strain rate 3.00 mm.min-1. The results indicated that Ni addition increased both the melting point and solidification range of the Sn-9Zn solder alloy. The microstructures of newly developed ternary Sn-9Zn-xNi solder alloys consisted of fine needle-like α-Zn phase dispersed in the β-Sn matrix. It was found that small amount of Ni (0.25 wt. %) addition refined and dispersed the Zn needles throughout the matrix. Besides, enhanced precipitation of Zn in the β-Sn matrix was also observed. All these structural changes increased the hardness and tensile strength of Sn-9Zn alloy with the addition of Ni particle to a certain amount.
In this study, the effect of Cu-coated multi-walled carbon nanotubes (MWCNTs) on the tensile strength of 70Sn-30Bi solder alloy has been investigated. Copper was first deposited onto metal-activated MWCNTs by an electroless process and confirmed with a scanning electron microscope and energy dispersive spectroscopy. Sn-Bi alloy solder was reinforced with Cucoated MWCNTs with additions of 0.5 wt.%, 1 wt.%, 2 wt.%, and 3 wt.%, respectively. 70Sn-30Bi solder was produced by melting pure tin and bismuth in an inert gas atmosphere. Cu-coated MWCNTs were then added into the metal matrix by cold rolling, followed by hot pressing to disperse the carbon nanotubes (CNTs) in the matrix. Tensile tests were conducted on an mechanical testing and simulation (MTS) tester. The tensile strength was found to be proportional to the addition of Cu/MWCNTs, and about 47.6% increase in tensile strength over the pure alloy has been obtained for an addition of 3 wt.% Cu/MWCNTs. The Cu coating may enhance CNT dispersion to prevent tangling.
In the current study, a modified sol-gel route was followed to produce undoped and Sm3+ doped (1, 3 and 5 mol %) nanoparticles. The study of opto-structural properties of Sm3+ doped NPs was carried out both experimentally and theoretically. Complete dissolution of Sm3+ ions into the ZnO lattice was obvious from XRD analysis. Morphological evolution with doping was studied using FESEM and TEM. XPS was carried out to confirm the presence of Sm3+ on the surface of the doped NPs. Increasing dopant quantity resulted in a red shift of the NPs along with a reduction in band gap with increasing absorption in the visible range, and a minimum of 3.18 eV of optical band gap for Zn0.97Sm0.03O was found. Photoluminescence spectroscopy revealed a drop in the recombination rate of electron-hole with increasing doping till 3 mole %, followed by an increase for Zn0.95Sm0.05O. Photogenerated electron-hole pair recombination was revealed by the orange band in the luminescence spectra. Theoretical analysis was also carried out with density function theory (DFT). This work also unfolds the fundamental understanding of the structural properties of the synthesized NPs to enhance photocatalytic activity successfully. Later, photocatalytic activity for the optimum composition i.e., 3 mole percent, was assessed experimentally.
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