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Mechanical Engineering

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Faculty of Engineering University of Malaya

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Mechanical Properties Of Intermetallic Compounds In Electrodeposited Multilayered Thin Film At Small Scale By Nanoindentation May 2015

Mechanical Properties Of Intermetallic Compounds In Electrodeposited Multilayered Thin Film At Small Scale By Nanoindentation

Faculty of Engineering University of Malaya

Mechanical properties of intermetallic compounds (IMCs) which were formed in electrodeposited Cu/Sn and Cu/Ni/Sn multilayered thin film have been investigated. The layers of Cu, Sn and Ni were formed by electrodeposition technique using copper pyrophosphate, tin methanesulfonic and nickel Watts baths, respectively. After synthesis, samples were subjected to high temperature aging at 150 degrees C for 168 h. Two different types of intermetallics Cu3Sn and Cu6Sn5 were formed in Cu/Sn. After adding ultra-thin layer of Ni (70 nm) in between Cu and Sn layers, (Cu, Ni)(6)Sn-5 was formed after aging at similar condition to that of Cu/Sn. Tin whisker growth …


Tailoring Zno Nanostructures By Spray Pyrolysis And Thermal Annealing Apr 2015

Tailoring Zno Nanostructures By Spray Pyrolysis And Thermal Annealing

Faculty of Engineering University of Malaya

We report a novel synthesis of ZnO nanorods with hexagonal pyramid-like heads by a simple and low cost technique of spray pyrolysis with the help of zinc acetate and tin (IV) chloride pentahydrate precursors. In the present study, the growth of ZnO nanorods is optimized by varying a number of sprays and annealing temperatures in the synthesis process. FESEM analysis reveals that ZnO nanorods are observed when the number of sprays exceeds 150 and film-like structure is observed below 150 sprays. Nanorods are formed when the molar ratio of zinc acetate to tin (IV) chloride pentahydrate in the solution mixture …


Gas Sensing Properties Of Zinc Stannate (Zn2sno4) Nanowires Prepared By Carbon, Assisted Thermal Evaporation Process Jan 2015

Gas Sensing Properties Of Zinc Stannate (Zn2sno4) Nanowires Prepared By Carbon, Assisted Thermal Evaporation Process

Faculty of Engineering University of Malaya

Zn2SnO4 nanowires are successfully synthesized by a carbon assisted thermal evaporation process with the help of a gold catalyst under ambient pressure. The as-synthesized nanowires are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) equipped with an energy dispersive X-ray spectroscopy (EDS). The XRD patterns and elemental mapping via TEM-EDS clearly indicate that the nanowires are Zn2SnO4 with face centered spinel structure. HRTEM image confirms that Zn2SnO4 nanowires are single crystalline with an interplanar spacing of 0.26 nm, which is ascribed to the d-spacing of (3 1 1) planes of Zn2SnO4. The optimum …


Catalyst-Dependent Morphological Evolution By Interfacial Stress In Crystalline-Amorphous Core-Shell Germanium Nanowires Jan 2015

Catalyst-Dependent Morphological Evolution By Interfacial Stress In Crystalline-Amorphous Core-Shell Germanium Nanowires

Faculty of Engineering University of Malaya

Directing the morphological evolution of one-dimensional materials in order to tune their properties for a variety of practical applications in optical sensing and solar cells is an ongoing effort. Here, we establish a systematic method for exerting control over the morphology of nanowires (NWs) grown via a vapour-solid-solid (VSS) process from different metal catalysts. We use germanium, a technologically important material, to demonstrate how catalysts influence the axial growth rate of a crystalline core against the lateral vapour deposition of an amorphous shell which in turn deforms the NWs into straight, tapered or spiral geometries due to interfacial stress. Finite …


Intermixing Reactions In Electrodeposited Cu/Sn And Cu/Ni/Sn Multilayer Interconnects During Room Temperature And High Temperature Aging Dec 2014

Intermixing Reactions In Electrodeposited Cu/Sn And Cu/Ni/Sn Multilayer Interconnects During Room Temperature And High Temperature Aging

Faculty of Engineering University of Malaya

Current push for miniaturization and 3D packaging makes it important to understand reactions in interconnects with ultra small volume. In order to reduce processing time and to have more homogeneous interconnects, solder can be designed in a multilayer form with components layer thickness in the sub-micron or even nanometer range. In this work, reaction kinetics in multilayer interconnects consisting stacks of Cu/Sn/Cu and Cu/Ni/Sn/Ni/Sn deposited by electrodeposition were investigated at room temperature and 150 A degrees C. The progress of the reaction in the multilayers was monitored by using XRD, SEM and EDX. Results show that by inserting a 70 …