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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 …
Evaluating The Optical Properties Of Tio2 Nanofluid For A Direct Absorption Solar Collector
Evaluating The Optical Properties Of Tio2 Nanofluid For A Direct Absorption Solar Collector
Faculty of Engineering University of Malaya
Recent studies specify that designated nanofluids may increase the proficiency of direct absorption solar thermal collectors. To determine the efficiency of nanofluids in solar applications, their capability to change light energy to thermal energy must be identified (i.e., the absorption spectrum of the solar material). In view of that, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (200- 1100nm). In the first decade of nanofluid research, most of the focus was on measuring and modeling the fundamental thermophysical properties of nanofluids (i.e., thermal conductivity, density, viscosity, and convection coefficients). …
The Tribological And Electrochemical Behavior Of Hvof-Sprayed Cr3c2-Nicr Ceramic Coating On Carbon Steel
Faculty of Engineering University of Malaya
High Velocity Oxygen Fuel (HVOF) is an excellent approach to prepare a good, wear-resistant lamella of Chromium Carbide-Nickel Chrome (Cr3C2-NiCr) on carbon steel for high temperature application. This research investigates the effect of a thin, deposited layer of Cr3C2-NiCr on carbon steel in terms of wear and corrosion properties. The microstructure of the HVOF-sprayed Cr3C2-NiCr coating was characterized at each step by scanning electron microscopy. Wear testing was performed with a pin-on-disk tester. Wear weight loss was examined by applying different loads over a 9048.96 m sliding distance. Experimental results show that the wear resistance of the coated sample reduced …
Electrowetting Of Room Temperature Ionic Liquids (Rtils) For Capillary Force Manipulation, Abhay Vasudev, Ashish Jagtiani, Li Du, Jun Hu, Yanan Gao, Jiang Zhe
Electrowetting Of Room Temperature Ionic Liquids (Rtils) For Capillary Force Manipulation, Abhay Vasudev, Ashish Jagtiani, Li Du, Jun Hu, Yanan Gao, Jiang Zhe
Dr. Jiang Zhe
The feasibility of using room temperature ionic liquids (RTILs) as the electrowetting liquid for capillary force microgrippers was studied. The non-volatility and thermal stability of ionic liquids make them suitable for droplet based microgripping application in high temperature and vacuum environments. Electrowetting on co-planar electrodes was utilized to dynamically change the contact angle of a 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6 ) liquid bridge to control the capillary lifting forces. The lifting force generated by the liquid bridge was experimentally characterized. The maximum capillary force was 146μN. The dynamic response of the BmimPF6 liquid bridge was also characterized.
Numerical Investigation Of Temperature Field During Sintering Of Bioceramic Nanoparticles By Pulse Lasers, Chang Ye, Gary Cheng
Numerical Investigation Of Temperature Field During Sintering Of Bioceramic Nanoparticles By Pulse Lasers, Chang Ye, Gary Cheng
Dr. Chang Ye
Traditional numerical study of the temperature field of laser thermal processing is based on two assumptions: 1. heat source is a surface heat flux, and 2. uniform material properties. This method is not accurate when it comes to the laser sintering of nanoparticle integrated bioceramics coating with certain porosity. In this paper, Heat transfer (HT) model and electromagnetic (EM) model is coupled to investigate the temperature field of bioceramics nanoparticles. The heat source calculated from EM field is simultaneously input into the HT model to calculate the temperature field of the nanoparticle assembly. The interaction between the nanoparticles in the …
Sintering Behaviour Of Natural Porous Hydroxyapatite Derived From Bovine Bone
Sintering Behaviour Of Natural Porous Hydroxyapatite Derived From Bovine Bone
Faculty of Engineering University of Malaya
The aim of this research is to study the properties of natural porous hydroxyapatite developed from bovine bone through a sintering process. Bovine bone samples were prepared and sintered in an air atmosphere at different temperatures ranging from 600 degrees C to 1000 degrees C. The sintered bodies were characterized to determine the phases present, bulk density, Ca/P ratio and Vickers hardness. In addition, the microstructural evolution of the sintered porous bodies was also examined. The results revealed that the thermal stability of the HA matrix was not disrupted and that all of the sintered bodies exhibited phase pure HA. …
Sintering Behaviour Of Natural Porous Hydroxyapatite Derived From Bovine Bone
Sintering Behaviour Of Natural Porous Hydroxyapatite Derived From Bovine Bone
Faculty of Engineering University of Malaya
The aim of this research is to study the properties of natural porous hydroxyapatite developed from bovine bone through a sintering process. Bovine bone samples were prepared and sintered in an air atmosphere at different temperatures ranging from 600 degrees C to 1000 degrees C. The sintered bodies were characterized to determine the phases present, bulk density, Ca/P ratio and Vickers hardness. In addition, the microstructural evolution of the sintered porous bodies was also examined. The results revealed that the thermal stability of the HA matrix was not disrupted and that all of the sintered bodies exhibited phase pure HA. …
Analysis Of Transient Natural Convection Flow Past An Accelerated Infinite Vertical Plate, Innovative Research Publications Irp India, Kaprawi S.
Analysis Of Transient Natural Convection Flow Past An Accelerated Infinite Vertical Plate, Innovative Research Publications Irp India, Kaprawi S.
Innovative Research Publications IRP India
This work describes a vertical hot plate moves with acceleration and with variation wall temperature. The temperatures of the plate decrease with the increase of velocity of the plate. The temperature and velocity are given by the governing equations. The dimensionless equations of the problem have been solved numerically by the finite difference method. The temperature and the velocity profiles against several parameters like Prandtl Number, Grashoft number and time are presented. The results show that the temperature and velocity profiles are significantly influenced by Prandtl and Grashoft number.
Review Of Improvements In Wire Electrode Properties For Longer Working Time And Utilization In Wire Edm Machining
Faculty of Engineering University of Malaya
Wire electrical discharge machining (WEDM) is an important technology, which demands high-speed cutting and high-precision machining to realize productivity and improved accuracy for manufacturing hard materials. WEDM has experienced explosive growth and complexity of equipment as well as rising demand for the basic process tool (the wire electrode). Greater taper angles, thicker workpieces, automatic wire threading, and long periods of unattended operation make the selection of the ideal wire a much more critical basis for achieving successful operation. This paper focuses on the evolution of EDM wire electrode technologies from using copper to the widely employed brass wire electrodes and …
Ab-10-017: Combined Effects Of Noise And Temperature On Human Comfort And Performance (1128-Rp), Dale Tiller, Lily M. Wang, Amy Musser, Matthew Radik
Ab-10-017: Combined Effects Of Noise And Temperature On Human Comfort And Performance (1128-Rp), Dale Tiller, Lily M. Wang, Amy Musser, Matthew Radik
Lily M Wang
This paper summarizes results from an experiment designed to investigate the combined effects of noise and temperature on human thermal comfort and task performance. Thirty subjects (16 females, 14 males) were exposed to all combinations of five thermal conditions (PMV +1 [79.6°F:26.4°C], PMV +0.5 [75.8°F:24.3°C], PMV 0 [72.1°F:22.3°C], PMV -0.5 [68.3°F:20.2°C], and PMV -1 [64.6°F:18.1°C]), three RC noise levels (RC-30, RC-40, and RC-50), and two sound qualities (neutral and rumbly): all sounds mimicked noise from building ventilation systems. After a one-hour adaptation period at each condition, subjects rated their thermal comfort using the ASHRAE Thermal Comfort Scale and the Tenant …
Preparation And Low-Temperature Sintering Of Cu Nanoparticles For High-Power Devices
Preparation And Low-Temperature Sintering Of Cu Nanoparticles For High-Power Devices
A.S. Md Abdul Haseeb
One of the fundamental requirements for high-temperature electronic packaging is reliable silicon attach with low and stable electrical resistance. This paper presents a study conducted on Cu nanoparticles as an alternative lead-free interconnect material for high-temperature applications. Cu nanoparticles were prepared using pulsed wire evaporation technique in water medium. Pure Cu nanoparticles without any organic mixture were used in this paper. An economical approach to extract the nanoparticles from water was established. In situ Cu nanoparticles oxide reduction was successfully done using forming gas $({\rm N}-{2}{\hbox{-}}5\%{\rm H}-{2})$. Cross-section analysis on bonded interface shows onset of Cu nanoparticles sintering at 400$^{\circ}{\rm …
Effect Of Temperature On Tribological Properties Of Palm Biodiesel
Effect Of Temperature On Tribological Properties Of Palm Biodiesel
A.S. Md Abdul Haseeb
Biodiesel, as an alternative fuel is steadily gaining attention to replace petroleum diesel partially or completely. The tribological performance of biodiesel is crucial for its application in automobiles. In the present study, effect of temperature on the tribological performance of palm biodiesel was investigated by using four ball wear machine. Tests were conducted at temperatures 30, 45, 60 and 75 °C, under a normal load of 40 kg for 1 h at speed 1200 rpm. For each temperature, the tribological properties of petroleum diesel (B0) and three biodiesel blends like B10, B20, B50 were investigated and compared. During the wear …
Characterization Of An N2 Flowing Microwave Post-Discharge By Oes Spectroscopy And Determination Of Absolute Ground-State Nitrogen Atom Densities By Talif, Et. Es-Sebbar, Y. Benilan, A. Jolly, M-C. Gazeau
Characterization Of An N2 Flowing Microwave Post-Discharge By Oes Spectroscopy And Determination Of Absolute Ground-State Nitrogen Atom Densities By Talif, Et. Es-Sebbar, Y. Benilan, A. Jolly, M-C. Gazeau
Dr. Et-touhami Es-sebbar
A flowing microwave post-discharge source sustained at 2.45 GHz in pure nitrogen has been investigated by optical emission spectroscopy (OES) and two-photon absorption laser-induced fluorescence (TALIF) spectroscopy. Variations of the optical emission along the post-discharge (near, pink and late afterglow) have been studied and the gas temperature has been determined. TALIF spectroscopy has been used in the late afterglow to determine the absolute ground-state nitrogen atomic densities using krypton as a reference gas. Measurements show that the microwave flowing post-discharge is an efficient source of N (4S) atoms in late afterglow. In our experimental conditions, the maximum N (4S) density …
A Technical Note On The Production Of Zirconia And Zircon Brick From Locally Available Zircon In Bangladesh
A.S. Md Abdul Haseeb
In this study, the potentiality of Bangladesh zircon as a raw material for zirconia and zircon brick production was examined. Decomposition of zircon (ZrSiO4) into zirconia (ZrO2) was attempted by using caustic soda (NaOH) as the decomposition agent. 5-10 μm size zircon, 5-30 wt.% NaOH, and decomposition temperatures ranging from 1300 to 1500°C were investigated. X-ray diffraction method using Mo Kα radiation was used in order to find out the extent of decomposition of zircon into zirconia. Zircon bricks of 0.06 mm× 0.06 mm× 0.025 mm shaped were made under a pressure of 15 MPa. Carboxi methyal cellulose (CMC) and …
An Experimental Study Of Molten Microdroplet Surface Deposition And Solidification: Transient Behavior And Wetting Angle Dynamics, Daniel Attinger, Z. Zhao, D. Poulikakos
An Experimental Study Of Molten Microdroplet Surface Deposition And Solidification: Transient Behavior And Wetting Angle Dynamics, Daniel Attinger, Z. Zhao, D. Poulikakos
Daniel Attinger
The basic problem of the impact and solidification of molten droplets on a substrate is of central importance to a host of processes. An important and novel such process in the area of micromanufacturing is solder jetting where microscopic solder droplets are dispensed for the attachment of microelectronic components. Despite the recent appearance of a few numerical studies focusing on the complex transient aspects of this process, no analogous experimental results have been reported to date to the best of our knowledge. Such a study is reported in this paper. Eutectic solder (63Sn37Pb) was melted to a preset superheat and …
Laminar Natural Convection In A Discretely Heated Cavity: I—Assessment Of Three-Dimensional Effects, Theodore J. Heindel, S. Ramadhyani, F. P. Incropera
Laminar Natural Convection In A Discretely Heated Cavity: I—Assessment Of Three-Dimensional Effects, Theodore J. Heindel, S. Ramadhyani, F. P. Incropera
Theodore J. Heindel
Two and three-dimensional calculations have been performed for laminar natural convection induced by a 3 × 3 array of discrete heat sources flush-mounted to one vertical wall of a rectangular cavity whose opposite wall was isothermally cooled. Edge effects predicted by the three-dimensional model yielded local and average Nusselt numbers that exceeded those obtained from the two-dimensional model, as well as average surface temperatures that were smaller than the two-dimensional predictions. For heater aspect ratios Ahtr ≲ 3, average Nusselt numbers increased with decreasing Ahtr . However, for Ahtr ≳ 3, the two and three-dimensional predictions were within 5 percent …