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Mechanical Engineering

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Haseeb ASMA

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Stability Of Molybdenum Nanoparticles In Sn-3.8ag-0.7cu Solder During Multiple Reflow And Their Influence On Interfacial Intermetallic Compounds, Haseeb Asma Feb 2013

Stability Of Molybdenum Nanoparticles In Sn-3.8ag-0.7cu Solder During Multiple Reflow And Their Influence On Interfacial Intermetallic Compounds, Haseeb Asma

Haseeb ASMA

This work investigates the effects of molybdenum nanoparticles on the growth of interfacial intermetallic compound between Sn-3.8Ag-0.7Cu solder and copper substrate during multiple reflow. Molybdenum nanoparticles were mixed with Sn-3.8Ag-0.7Cu solder paste by manual mixing. Solder samples were reflowed on a copper substrate in a 250 degrees C reflow oven up to six times. The molybdenum content of the bulk solder was determined by inductive coupled plasma-optical emission spectrometry. It is found that upon the addition of molybdenum nanoparticles to Sn-3.8Ag-0.7Cu solder, the interfacial intermetallic compound thickness and scallop diameter decreases under all reflow ...


Nanoindentation And Micro-Mechanical Fracture Toughness Of Electrodeposited Nanocrystalline Ni-W Alloy Films, Haseeb Asma Apr 2012

Nanoindentation And Micro-Mechanical Fracture Toughness Of Electrodeposited Nanocrystalline Ni-W Alloy Films, Haseeb Asma

Haseeb ASMA

Nanocrystalline nickel-tungsten alloys have great potential in the fabrication of components for microelectromechanical systems. Here the fracture toughness of Ni-12.7 at.%W alloy micro-cantilever beams was investigated. Micro-cantilevers were fabricated by UV lithography and electrodeposition and notched by focused ion beam machining. Load was applied using a nanoindenter and fracture toughness was calculated from the fracture load. Fracture toughness of the Ni-12.7 at.%W was in the range of 1.49-5.14 MPa root m. This is higher than the fracture toughness of Si (another important microelectromechanical systems material), but considerably lower than that of electrodeposited nickel and ...


Preparation And Low-Temperature Sintering Of Cu Nanoparticles For High-Power Devices, Haseeb Asma Apr 2012

Preparation And Low-Temperature Sintering Of Cu Nanoparticles For High-Power Devices, Haseeb Asma

Haseeb ASMA

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 (N-2-5% H-2). Cross-section analysis on bonded interface shows onset of Cu nanoparticles sintering at 400 degrees ...


Effects Of Addition Of Copper Particles Of Different Size To Sn-3.5ag Solder, Haseeb Asma Jan 2012

Effects Of Addition Of Copper Particles Of Different Size To Sn-3.5ag Solder, Haseeb Asma

Haseeb ASMA

In this study, copper particles with different sizes 20-30 nm, 3 and 10 mu m were incorporated into Sn-3.5Ag solder paste to form Sn-Ag-Cu composite solder. The Cu particles were added at 0.7 and 3% by paste mixing for 30 min. The composite solder samples were prepared on copper substrate at 240A degrees C for 60 s. Differential scanning calorimetry was conducted to measure the melting point of the composite solder. The wetting angle and microstructure of the composite solder were studied using optical microscope and scanning electron microscope. Micro hardness was measured using a 10 gf load ...


Die Attach Properties Of Zn-Al-Mg-Ga Based High-Temperature Lead-Free Solder On Cu Lead-Frame, Haseeb Asma Jan 2012

Die Attach Properties Of Zn-Al-Mg-Ga Based High-Temperature Lead-Free Solder On Cu Lead-Frame, Haseeb Asma

Haseeb ASMA

Several candidate alloys have been suggested as high-temperature lead-free solder for Si die attachment by different researchers. Among them, Zn-Al based alloys have proper melting range and excellent thermal/electrical properties. In this study, Zn-Al-Mg-Ga solder wire was used to attach Ti/Ni/Ag metallized Si die on Cu lead-frame in an automatic die attach machine. Die attachment was performed in a forming gas environment at temperature ranging from 370 to 400 A degrees C. At the interface with Cu lead-frame, CuZn(4), Cu(5)Zn(8) and CuZn intermetallic compound (IMC) layers were formed. At the interface with Si ...


Development Of A Compression Test Device For Investigating Interaction Between Diffusion Of Biodiesel And Large Deformation In Rubber, Haseeb Asma Dec 2011

Development Of A Compression Test Device For Investigating Interaction Between Diffusion Of Biodiesel And Large Deformation In Rubber, Haseeb Asma

Haseeb ASMA

Motivated by environmental and economic factors, biodiesel has been introduced to partially replace the diminishing stock of petroleum-based fuel. However, the use of biodiesel such as palm biodiesel is placing additional demands on automotive components, e.g. rubber components, due to a compatibility issue in the fuel system. In engineering applications where hostile environments are involved, the long-term mechanical response of rubber components is affected by interactions existed between diffusion of liquids into the material and fluctuating multiaxial loading. Hence, it is crucial to investigate the durability of rubber components in this aggressive environment. A number of studies on static ...


Effect Of Different Corrosion Inhibitors On The Corrosion Of Cast Iron In Palm Biodiesel, Haseeb Asma Nov 2011

Effect Of Different Corrosion Inhibitors On The Corrosion Of Cast Iron In Palm Biodiesel, Haseeb Asma

Haseeb ASMA

Biodiesel is currently in regular use as an alternative fuel over conventional petroleum diesel. However, corrosion of automotive materials is one of the concerns related to biodiesel compatibility issues. In addition, auto-oxidation of biodiesel can also enhance the corrosiveness of biodiesel. The present study aims to investigate inhibition effect of ethylenediamine (EDA), n-butylamine (nBA), tert-butylamine (TBA) against corrosion of cast iron. Static immersion tests in biodiesel in the presence (100 ppm) and absence of different corrosion inhibitors were carried out at room temperature for 1200 hours. At the end of the test, corrosion characteristic was investigated by weight loss measurements ...


Effects Of Co Nanoparticle Addition To Sn-3.8ag-0.7cu Solder On Interfacial Structure After Reflow And Ageing, Haseeb Asma Apr 2011

Effects Of Co Nanoparticle Addition To Sn-3.8ag-0.7cu Solder On Interfacial Structure After Reflow And Ageing, Haseeb Asma

Haseeb ASMA

Effects of Co nanoparticle additions to Sn-3.8Ag-0.7Cu on the structure of solder/copper interface have been studied after reflow and high temperature ageing (150 degrees C, up to 1008 h). Results show that the Co nanoparticles substantially suppress the growth of Cu(3)Sn but enhance Cu(6)Sn(5) growth. Cobalt nanoparticles reduce interdiffusion coefficient in Cu(3)Sn. It is suggested that the Co nanoparticles undergo surface dissolution during reflow and exert their influence, at least partially, through alloying effect. (C) 2011 Elsevier Ltd. All rights reserved.


Degradation Of Physical Properties Of Different Elastomers Upon Exposure To Palm Biodiesel, Haseeb Asma Mar 2011

Degradation Of Physical Properties Of Different Elastomers Upon Exposure To Palm Biodiesel, Haseeb Asma

Haseeb ASMA

Biodiesel, as an alternative fuel, is gradually receiving more popularity for use in internal combustion engines. However questions continue to arise with regard to its compatibility with elastomeric materials. The present work aims to investigate the comparative degradation of physical properties for different elastomers [e.g. ethylene propylene diene monomer (EPDM), silicone rubber (SR), polychloroprene (CR), polytetrafluroethylene (PTFE) and nitrile rubber (NBR)] upon exposure to diesel and palm biodiesel. Static immersion tests in B0(diesel), B10 (10% biodiesel in diesel), B20, B50 and B100(biodiesel) were carried out at room temperature (25 degrees C) for 1000 h. Different physical properties ...


Comparative Corrosive Characteristics Of Petroleum Diesel And Palm Biodiesel For Automotive Materials, Haseeb Asma Oct 2010

Comparative Corrosive Characteristics Of Petroleum Diesel And Palm Biodiesel For Automotive Materials, Haseeb Asma

Haseeb ASMA

Corrosive characteristics of biodiesel are important for long term durability of engine parts. The present study aims to compare the corrosion behavior of aluminum, copper and stainless steel in both petroleum diesel and palm biodiesel. Immersion tests in biodiesel (B100) and diesel (B0) were carried out at 80 degrees C for 1200 h. At the end of the test, corrosion characteristic was investigated by weight loss measurements and changes on the exposed metal surface. Surface morphology was examined by optical microscope and scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDS). Fuels were analyzed by using TAN analyzer. FTIR ...


Structural Investigations On Nanocrystalline Ni-W Alloy Films By Transmission Electron Microscopy, Haseeb Asma Oct 2009

Structural Investigations On Nanocrystalline Ni-W Alloy Films By Transmission Electron Microscopy, Haseeb Asma

Haseeb ASMA

Electrode posited Ni-W alloys have been investigated in the as-deposited state by transmission electron microscopy in order to investigate the microstructural features in dependence of the tungsten content. Within the tungsten content range from 7 at.% up to 12 at.%, the microstructure is nanocrystalline characterized by a bimodal grain size distribution, consisting out of 20 to 200 nm sized grains and also larger grains with several 100 mm characteristic dimension. No clear trend in microstructure formation is visible with W content or deposition conditions in the investigated W content range. Only solid solution phase characteristics were observed. The lattice constant ...


Spreading Profile Of Dopant Solution On Pre-Sintered Silica Layers For Selective Area Doping Of Integrated Optic Planar Glass Samples, Haseeb Asma Jan 2009

Spreading Profile Of Dopant Solution On Pre-Sintered Silica Layers For Selective Area Doping Of Integrated Optic Planar Glass Samples, Haseeb Asma

Haseeb ASMA

The spread profile of potassium-permanganate (KMnO(4)) dye on a porous pre-sintered silica layer deposited via Flame Hydrolysis Deposition is presented. The work is aimed at controlling the dopant profile on the resulting glass layer for optically passive and active devices integration. KMnO(4) is used as it allows visual qualification of its spread on the soot layer. Pre-sintered silica layers allow for application of dopants into the glass matrix via adsorption and pore retention. Selective area doping is achieved by applying specific volumes of the dye onto pre-selected areas on the sample using a micropipette. Higher dye volumes applied ...


Thermal Stability Of Electrodeposited Liga Ni-W Alloys For High Temperature Mems Applications, Haseeb Asma Oct 2008

Thermal Stability Of Electrodeposited Liga Ni-W Alloys For High Temperature Mems Applications, Haseeb Asma

Haseeb ASMA

For thermally stable LIGA materials for high temperature MEMS applications LIGA Ni-W layers and micro testing samples with different compositions (15 and 5 at% W) were electrodeposited. In order to investigate the thermal stability the Ni-W layers were annealed at different temperatures (300-700 degrees C) and for different durations (1, 4, 16 h). Their microstructure and micro-hardness were than analysed after annealing and compared with those of as-deposited states. The observed microstructures show, in comparison to pure LIGA nickel, a small grain growth and a relatively stable structure up to 700 degrees C. The micro-hardness values of the LIGA Ni-W ...


Production And Purification Of Zircon Opacifier From Zircon Found In The Coastal Area Of Bangladesh, Haseeb Asma Aug 2008

Production And Purification Of Zircon Opacifier From Zircon Found In The Coastal Area Of Bangladesh, Haseeb Asma

Haseeb ASMA

In this study the potentiality of Bangladesh zircon as a raw material for opacifier was examined. Preparation of zircon flour was done by both wet and dry ball milling. Wet milling of zircon was found to be much efficient than dry milling. Zircon flour of peak size 8 mu m obtained by wet milling was purified by leaching in concentrated H(2)SO(4) acid. Leaching time was varied from 2 to 20 h and sulphuric acid concentration ranged from 10 to 80 ml/l. Both un-purified and purified Bangladesh zircon flour were tested for their performance as opacifier in ...


Liga Fabrication Of Nanocrystalline Ni-Walloy Micro Specimens From Ammonia-Citrate Bath, Haseeb Asma Mar 2008

Liga Fabrication Of Nanocrystalline Ni-Walloy Micro Specimens From Ammonia-Citrate Bath, Haseeb Asma

Haseeb ASMA

Ammonia-citrate bath has been investigated for the deposition of nano crystalline Ni - W alloy micro components using the LIGA process. First the bath stability and deposit characteristics were studied. Fabrication of micro specimens were then carried out on silicon substrates covered with novolac as well as thick PMMA resist for LIGA. Effects of different parameters like current density, nickel ion and tungsten ion concentration in the bath, deposition time etc. on the deposit characteristics and current efficiency were studied. The deposited Ni - W samples were characterized by scanning electron microscopy, energy depressive X-ray spectroscopy, light optical microscopy and X-ray diffraction ...


Friction And Wear Characteristics Of Electrodeposited Nanocrystalline Nickel-Tungsten Alloy Films, Haseeb Asma Jan 2008

Friction And Wear Characteristics Of Electrodeposited Nanocrystalline Nickel-Tungsten Alloy Films, Haseeb Asma

Haseeb ASMA

Electrodeposited nanocrystalline nickel-tungsten alloys are being investigated as an attractive alternative to electrodeposited nickel for applications involving fabrication of micro electro mechanical systems (MEMS). Ni-W alloys are also being considered as an environmentally friendly alternative to hard chrome plating in some cases. In applications involving sliding contacts such as in micro-gears in MEMS, mould inserts, etc., tribological properties of Ni-W alloys would be of relevance. In this work, the sliding friction and wear characteristics of Ni-W alloys with different tungsten contents were investigated and compared with that of nickel film deposited from sulphamate bath commonly used in microfabrication. For wear ...


Study Of The Wear Behaviour Of Al-4.5% Cu-3.4% Fe In Situ Composite: Effect Of Thermal And Mechanical Processing, Haseeb Asma Feb 2007

Study Of The Wear Behaviour Of Al-4.5% Cu-3.4% Fe In Situ Composite: Effect Of Thermal And Mechanical Processing, Haseeb Asma

Haseeb ASMA

Al-Cu-based MMCs reinforced by Al-Fe intermetallics are investigated for their wear behaviour. The composite (Al-4.5 mass% Cu-3.4 mass% Fe) was produced by solidification processing where the Al-Fe-based intermetallic formed in situ in a matrix of mainly Al-Cu alloy. The effects of thermal and mechanical processing, viz., as-cast condition, solution treatment, aging and hot rolling on the wear behaviour of the composites were examined. The composites were characterized by optical microscopy, SEM, microhardness measurements and X-ray diffraction. The wear behaviour of the composites was studied in a pin-on-disc type wear apparatus. The as-cast in situ composite exhibited the highest ...


Tribo-Surface Characteristics Of Al-B4c And Al-Sic Composites Worn Under Different Contact Pressures, Haseeb Asma Sep 2006

Tribo-Surface Characteristics Of Al-B4c And Al-Sic Composites Worn Under Different Contact Pressures, Haseeb Asma

Haseeb ASMA

Tribo-surface characteristics of two aluminium metal matrix composites (Al-MMC) of compositions Al-13 vol%B4C and Al-13 vol%SiC sliding against a commercial phenolic brake pad have been investigated under dry conditions. The wear tests were carried out using a pin-on-disc type apparatus at a linear speed of 1.62 ms(-1) under contact pressures ranging from 0.75 to 3.00 MPa. The coefficient of friction was recorded on line. Wear rates were calculated from mass loss measurements. Scanning electron microscope equipped with energy dispersive X-ray spectroscopy was used to examine the tribo-surface. It is found that wear rate of ...


Modeling Of The Effects Of Athermal Flow Strength And Activation Energy For Dislocation Glide An The Nanoindentation Creep Of Nickel Thin Film At Room Temperature, Haseeb Asma Sep 2006

Modeling Of The Effects Of Athermal Flow Strength And Activation Energy For Dislocation Glide An The Nanoindentation Creep Of Nickel Thin Film At Room Temperature, Haseeb Asma

Haseeb ASMA

Nanoindentation creep behaviour of nickel at room temperature has been modeled based on the obstacle-controlled dislocation glide mechanism. Using the model, the effects of two important materials parameters viz. the activation free energy required by dislocation to overcome an obstacle without any aid from external stress, Delta F and the athermal flow strength, tau(0), which is the flow strength of solids at 0 K are systematically studied. It has been found that Delta F plays a dominant role in room temperature creep properties of nickel. The role of Delta F is particularly dominant in determining the time dependent deformation ...


Microstructure And Interface Characteristics Of B4c, Sic And Al2o3 Reinforced Al Matrix Composites: A Comparative Study, Haseeb Asma Dec 2003

Microstructure And Interface Characteristics Of B4c, Sic And Al2o3 Reinforced Al Matrix Composites: A Comparative Study, Haseeb Asma

Haseeb ASMA

Three aluminium metal matrix composites containing reinforcing particles of B4C, SiC and Al2O3 (0-20 vol.%) were processed. The stir-casting manufacturing route followed by hot extrusion was utilized, being one of the cost-effective industrial methods. A clear interfacial reaction product/layer was found at Al-SiC interface for composites held for a relatively long processing time (>30 min). No reaction product was observed at Al-B4C and Al-Al2O3 interfaces at the resolution limit of the SEM used. On the other hand, two secondary phases (alumina and another phase containing aluminium, boron and carbon) were found in the aluminum matrix away from the interface ...


Study On The Nature Of The Electrochemically Synthesized Hard Fe-15.4 Mass % Ni-0.70 Mass % C Alloy Film, Haseeb Asma Apr 2003

Study On The Nature Of The Electrochemically Synthesized Hard Fe-15.4 Mass % Ni-0.70 Mass % C Alloy Film, Haseeb Asma

Haseeb ASMA

Electrochemical synthesis of hard Fe-15.4 mass% Ni-0.70 mass% C alloy film with a hardness 750 HV was carried out from sulfate-based bath containing a small amount of citric acid and L-ascorbic acid. The nature of the alloy was investigated by different characterization techniques including x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, Mossbauer spectroscopy, differential scanning calorimetry, and magnetic measurements. The decomposition behavior of the alloy was also studied and compared with that of thermally prepared martensite. It was found that the electrochemically deposited Fe-Ni-C alloy exists in a state that is ahead of the ...