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Influence of Surface Passivation on Optical Properties of Spray Pyrolysis Deposited Pd-F:SnO2
Patrick Mwinzi Mwathe,
Robinson Musembi,
Mathew Munji,
Benjamin Odari,
Lawrence Munguti,
Alex Alfred Ntilakigwa,
John Nguu,
Bernard Aduda,
Boniface Muthoka
Issue:
Volume 3, Issue 5, September 2014
Pages:
137-142
Received:
7 August 2014
Accepted:
26 August 2014
Published:
10 September 2014
Abstract: Pd-F:SnO2 thin films have been prepared by spray pyrolysis technique using an alcoholic precursor solution consisting of stannic chloride (SnCl4.5H20), ammonium fluoride (NH4F) and palladium chloride (PdCl2). Optimization on the deposition parameters has been done in order to obtain high quality thin films. The effect of varying the fluorine content on the optical properties of Pd-F:SnO2 thin films were studied. Data for transmittance and reflectance in the wavelength range from 300nm – 2500nm was measured using the solid spec 3700DUV spectrophotometer. The calculated optical band gap of the as prepared thin films has been found to range from 3.8eV to 4.11eV. Fluorine incorporation for Pd-F:SnO2 has been found to have a narrowing effect on the band gap, but at its higher concentration the band gap has been seen to increase. The band gap narrowing is due to the incorporation of F- ions in the crystal lattice therefore giving rise to donor levels in the SnO2 band gap which is an essential characteristic for the gas sensor applications. Both annealing and passivation have been found to have very insignificant change in optical band gap of Pd-F:SnO2.
Abstract: Pd-F:SnO2 thin films have been prepared by spray pyrolysis technique using an alcoholic precursor solution consisting of stannic chloride (SnCl4.5H20), ammonium fluoride (NH4F) and palladium chloride (PdCl2). Optimization on the deposition parameters has been done in order to obtain high quality thin films. The effect of varying the fluorine conten...
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Influence of Firing Temperature on Physical Properties of Same Clay and Pugu Kaolin for Ceramic Tiles Application
Hashimu Hamisi,
Seungyong Eugene Park,
Byung-Hyun Choi,
Yong-Taie An,
Lee Jeongin
Issue:
Volume 3, Issue 5, September 2014
Pages:
143-146
Received:
13 August 2014
Accepted:
26 August 2014
Published:
10 September 2014
Abstract: This study focuses on the effect of firing temperature on the physical properties of Same clay and Pugu kaolin for potential application in ceramic tiles. X-Ray diffractometer (XRD) is used to analyze the phases formed after firing. XRD result shows that quartz, sillimanite and cristobalite appears at temperature beyond 1200oC while mullite phase develops in Pugu kaolin. Pugu kaolin shows low porosity (1.3%) at 1400oC compared to that of Same clay (12.7%). Water absorption at 1200oC is 7.8 % for Pugu kaolin and sharply reduced to 0.47% at a temperature between 1300oC to 1400oC suggesting complete sintering to have taken place at this temperature.
Abstract: This study focuses on the effect of firing temperature on the physical properties of Same clay and Pugu kaolin for potential application in ceramic tiles. X-Ray diffractometer (XRD) is used to analyze the phases formed after firing. XRD result shows that quartz, sillimanite and cristobalite appears at temperature beyond 1200oC while mullite phase d...
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Preparation and Structural Characterization of Sol-Gel-Derived Silver Silica Nanocomposite Powders
Duy Phong Pham,
Kim Khanh Huynh,
Cao Vinh Tran,
Van Quang Vu,
Thi Thanh Van Tran
Issue:
Volume 3, Issue 5, September 2014
Pages:
147-151
Received:
30 May 2014
Accepted:
23 August 2014
Published:
10 September 2014
Abstract: The silver embedded silica powders (Ag/SiO2) have been successfully prepared by sol-gel method. Ag nanoparticles were formed from the thermal decomposition of the silver nitrate. X-ray diffraction shows that the silver nanocrystals have appeared after a heat-treatment at 600 °C. TEM images show that the spherical silver particles with an average size around 30 nm dispersed homogeneously in silica matrix. The data of XRD, Raman and FTIR spectroscopy prove that the formation of the silver nanocrystals influent on the structural evolution of the silica matrix. The presence of metal nanocrystals leads to remarkable decrease in crystallizing temperature of SiO2. In addition, the adsorption-desorption analysis indicated that the growth of Ag particles makes the pores in silica structure widen.
Abstract: The silver embedded silica powders (Ag/SiO2) have been successfully prepared by sol-gel method. Ag nanoparticles were formed from the thermal decomposition of the silver nitrate. X-ray diffraction shows that the silver nanocrystals have appeared after a heat-treatment at 600 °C. TEM images show that the spherical silver particles with an average si...
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Characterization of Al2O3/Al/Al2O3 Joints with Ti+Cr Interlayer
Marzanna,
Maria Ksiazek,
Maria,
Wieslawa Richert,
Lukasz,
Rafal Boron,
Adam Tchorz
Issue:
Volume 3, Issue 5, September 2014
Pages:
152-158
Received:
20 August 2014
Accepted:
28 August 2014
Published:
10 September 2014
Abstract: Joints of Al2O3/Al/Al2O3 are formed by liquid – state bonding of alumina substrates covered with thin Ti+Cr film of 380 nm thickness using an Al interlayer of 30 µm at 973 K under a vacuum of 0.2 mPa applied for 5 minutes and at a pressure of 0.01 MPa. The bond strength of the joints is examined by a four – point bend testing at room temperature, coupled with optical, scanning and transmission electron microscopy. Results show that introduction of the thin Ti+Cr film layer: (i) improves plasticity in the metal layer of Al2O3/Al/Al2O3 joints, (ii) has positive effect on structure transformation in the interface and leads to fabrication of reliable metal-ceramic joints. Information obtained from the wetting characteristics of liquid Al on alumina substrate coated by thin Ti+Cr film indicates that the contact angle can be reduced to even less than 60°. Microstructural investigations of the interface of Al2O3/Ti+Cr/Al/Ti+Cr/Al2O3 joints carried out by SEM and TEM techniques indicated that the precipitates of intermetallic phases rich in both Ti and Cr as well as Al2O3 were formed at the Al/Al2O3 interface, which influenced strengthening of these joints. Hence a conclusion can be drawn that the interface structure influences the mechanical durability increase in Al/Al2O3 joints.
Abstract: Joints of Al2O3/Al/Al2O3 are formed by liquid – state bonding of alumina substrates covered with thin Ti+Cr film of 380 nm thickness using an Al interlayer of 30 µm at 973 K under a vacuum of 0.2 mPa applied for 5 minutes and at a pressure of 0.01 MPa. The bond strength of the joints is examined by a four – point bend testing at room temperature, c...
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Preparation of Activated Carbon from Oil Palm Empty Fruit Bunch (EFB) by Steam Activation Using Response Surface Methodology
Sharifah Aishah Syed A. Kadir,
Sharmeela Matali,
Nor Fadilah Mohamad,
Noor Hidayu Abdul Rani
Issue:
Volume 3, Issue 5, September 2014
Pages:
159-163
Received:
4 August 2014
Accepted:
21 August 2014
Published:
20 September 2014
Abstract: This paper aims to find the optimum conditions for preparation of activated carbon from empty fruit bunch (EFB) using physical steam activation by applying response surface methodology (RSM) with maximizing the BET surface area. The main process variables for this study were activation temperature and activation time and quadratic model was developed for a BET surface area which was selected as the investigated response. According to the RSM tool, the optimum conditions that were obtained from this study are at an activation temperature of 764.5oC and activation time of 77 min which give the maximum of BET surface area; 717.6 m2/g. Based on this optimum condition, the experimental value of BET surface area is 720.0 m2/g and is found to agree adequately with that (717.6 m2/g) predicted from the model.
Abstract: This paper aims to find the optimum conditions for preparation of activated carbon from empty fruit bunch (EFB) using physical steam activation by applying response surface methodology (RSM) with maximizing the BET surface area. The main process variables for this study were activation temperature and activation time and quadratic model was develop...
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Recycling of Scrap Tyres
Sudha Rani,
Rajesh Agnihotri
Issue:
Volume 3, Issue 5, September 2014
Pages:
164-167
Received:
30 July 2014
Accepted:
18 August 2014
Published:
20 September 2014
Abstract: Environmental distress harms concerning the possibility of using tyre rubber waste as raw materials for the research of liquid This research explain the use of tyre pyrolysis oils by solving the difficulty of waste tyre removal. In this study pyrolysis of scrap tyres was approved in controlled environment in Rotary bed horizontal batch reactor of 10T capacity at a high temperature of 430oC to create pyrolytic oil, non-condensable gases, steel wires and char.This paper also provides the physical properties of pyrolytic oil and compare with the diesel oil.
Abstract: Environmental distress harms concerning the possibility of using tyre rubber waste as raw materials for the research of liquid This research explain the use of tyre pyrolysis oils by solving the difficulty of waste tyre removal. In this study pyrolysis of scrap tyres was approved in controlled environment in Rotary bed horizontal batch reactor of 1...
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Thermo-Mechanical Chain Branching of Commercial High Density Polyethylene during Extrusion
Yadollah Teymouri,
Saeed Houshmandmoayed,
Mohammad Adibfar,
Reza Rashedi
Issue:
Volume 3, Issue 5, September 2014
Pages:
168-176
Received:
17 August 2014
Accepted:
25 August 2014
Published:
20 September 2014
Abstract: Two different phenomena may affect average molecular weight (Mw) of molten polyethylene during extrusion process. The first is crosslinking, which can be divided to two categories of chain branching and network formation, leading to an increase in Mw. The second is chain scission which leads to a decrease in the average Mw. In this work, chain branching of molten stabilized pipe grade high density polyethylene (HDPE) and unstabilized one, extruded in industrial twin screw extruder, has been studied. Therefore a series of analytical techniques including melt flow rate (MFR), capillary rheometer, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and Fourier transform infrared spectroscopy (FTIR) were employed. The unstabilized samples' MFR were lower than stabilized ones' which showed a higher melt viscosity of unstabilized samples due to their higher Mw. By applying rheometry test in different modes, the unstabilized PE samples showed a higher shear viscosity in comparison with stabilized ones agreeing with MFR results. DSC results showed a difference in degree of crystallinity between samples. This difference was verified by DMA result of solid state which showed a higher shear storage modulus for stabilized samples. Also, DMA results confirmed the obtained results from rheometry test in melt state. Additionally, FTIR results of stabilized and unstabilized samples demonstrated the difference between their chemical structures. Although it seems that the level of chain branching in this grade of HDPE is low howover, all techniques' results are in a good agreement which makes the provided results and data reliable. Moreover, a combination of the applied methods in this work can be helpful to determine the validity and efficiency of antioxidants.
Abstract: Two different phenomena may affect average molecular weight (Mw) of molten polyethylene during extrusion process. The first is crosslinking, which can be divided to two categories of chain branching and network formation, leading to an increase in Mw. The second is chain scission which leads to a decrease in the average Mw. In this work, chain bran...
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High Temperature Diffusion in AlxGa1-xN and P-Type AlGaN by Al4C3
Dohyung Kim,
Heesub Lee,
Yoshiki Naoi,
Shiro Sakai
Issue:
Volume 3, Issue 5, September 2014
Pages:
177-182
Received:
17 August 2014
Accepted:
6 September 2014
Published:
20 September 2014
Abstract: The diffusion experiment of AlxGa1-xN (x = 0.00, 0.04, 0.45, 0.65, 0.86, 1.00) samples using a solid source of Al4C3 layer was performed by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE). The AlxGa1-xN (x≦0.45) samples were proven to be a p-type. In second ion mass spectroscopy (SIMS) analysis, the carbon profile is different from the simple complementary error function, but is the double of the complementary error function, meaning AlC or AlCO plus C. The diffusion length (L) was drastically decreased by increasing Al. The diffusion coefficient (D) was also calculated as a function of Al mole fraction.
Abstract: The diffusion experiment of AlxGa1-xN (x = 0.00, 0.04, 0.45, 0.65, 0.86, 1.00) samples using a solid source of Al4C3 layer was performed by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE). The AlxGa1-xN (x≦0.45) samples were proven to be a p-type. In second ion mass spectroscopy (SIMS) analysis, the carbon profile is different from the sim...
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A Study of Effects of Machining Parameters on Tool Life
Sunday Joshua Ojolo,
Olugbenga Ogunkomaiya
Issue:
Volume 3, Issue 5, September 2014
Pages:
183-199
Received:
21 August 2014
Accepted:
4 September 2014
Published:
20 September 2014
Abstract: This work involves the investigation carried out to study the effects of machining parameters on tool life under dry machining environment. Three cutting tool materials (HSS blank tool - M2 C66, tungsten carbide insert tool grade P-10, DMNG carbide insert tool 150412-SA) and work materials (medium carbon steel 0.4 wt% C, mild steel 0.29 wt% C, brass C330) were examined. The experiments were conducted under three different spindle speeds (900, 1120, 1400rev/min); feed rates (0.1, 0.2, 0.3mm/rev) and depths of cut (0.5, 1.0, 1.5mm). The settings of machining parameters were determined by using the Taguchi experimental design method. The level of importance of the machining parameters on tool life was determined by using analysis of variance (ANOVA). The optimum machining parameters combination was obtained by using the analysis of signal-to-noise (S/N) ratio. The relationship between cutting parameters and tool life was obtained. From the results, the spindle speed had the most significant effects on tool life followed by feed rate and the depth of cut. The life of the HSS when cutting the three work pieces (medium carbon steel, mild steel and brass) was 161s, 321s and 386s respectively. The life of tungsten carbide when cutting the three work materials was 480s, 726s and 1028s respectively. The life of DMNG carbide were 782s using medium carbon steel, 864s using mild steel, and 1183s using brass. The shortest life of the three cutting tool materials (HSS, tungsten carbide and DMNG carbide) on the three work material (medium carbon steel, mild steel and brass) occurred at cutting speed (1400 rev/min), feed rate (0.3 mm/rev) and depth of cut (1.5 mm), where the life of the HSS were (15s using medium carbon steel, 58s using mild steel, 94s using brass). The life of tungsten carbide were (135s using medium carbon steel, 180s using mild steel, 274s using brass) and the life of DMNG carbide were (219s using medium carbon steel, 215s using mild steel, 311s using brass). The increment of spindle speed, feed rate and depth of cut value mostly will affect the tool life.
Abstract: This work involves the investigation carried out to study the effects of machining parameters on tool life under dry machining environment. Three cutting tool materials (HSS blank tool - M2 C66, tungsten carbide insert tool grade P-10, DMNG carbide insert tool 150412-SA) and work materials (medium carbon steel 0.4 wt% C, mild steel 0.29 wt% C, bras...
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Transient Response in Aqueous Solution of an Anions Porous Silicon Based Sensor
Arturo Ramirez-Porras,
Natalia Murillo-Quiros
Issue:
Volume 3, Issue 5, September 2014
Pages:
200-204
Received:
22 August 2014
Accepted:
12 September 2014
Published:
30 September 2014
Abstract: A porous silicon based sensor has been developed to detect anions in a salt solution by the application of DC pulses on a Semiconductor/Electrolyte system. The sensor performance can be explained invoking a model where charge accumulation in the semiconductor surface states directly affects their geometric capacitances. By varying anions concentrations in salt solution, the results show a fairly constant value of substrate resistance, whereas variations in those geometric capacitances depend on the anion concentration. The constancy of substrate resistance and variability of geometric capacitance constitute key points for the development of an anion solution sensor.
Abstract: A porous silicon based sensor has been developed to detect anions in a salt solution by the application of DC pulses on a Semiconductor/Electrolyte system. The sensor performance can be explained invoking a model where charge accumulation in the semiconductor surface states directly affects their geometric capacitances. By varying anions concentrat...
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The Electro-Optical Characteristics of the AZO/Mo/AZO Transparent Conductive Film on PC Substrate
Tien-Chai Lin,
Wen-Chang Huang,
Fu-Chun Tsai
Issue:
Volume 3, Issue 5, September 2014
Pages:
205-209
Received:
29 August 2014
Accepted:
15 September 2014
Published:
30 September 2014
Abstract: The triple-layered transparent conductive oxide thin films, AZO/Mo/AZO (OMO) structure, is present in the paper. The OMO film is deposited on polycarbonate (PC) substrates by a co-sputtering process at room temperature. Metal Mo is chosen because of its chemical stable and low resistivity. The OMO film shows a great reduction of resistivity through the addition of Mo layer. The dependence of the AZO thickness of the electro-optical characteristic to the OMO film is also discussed. A best figure of merit (FOM) of 1.56 × 10-5 -1 with a sheet resistance of 530 Ω/□ and average transmittance of 62% is found at the OMO film of 130 nm thickness. At this condition, the AZO film shows a low resistivity due to its excellent crystallinity.
Abstract: The triple-layered transparent conductive oxide thin films, AZO/Mo/AZO (OMO) structure, is present in the paper. The OMO film is deposited on polycarbonate (PC) substrates by a co-sputtering process at room temperature. Metal Mo is chosen because of its chemical stable and low resistivity. The OMO film shows a great reduction of resistivity through...
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Engineering Design and Manufacturing Infrastructure Availability and Supply in Ghana
Issue:
Volume 3, Issue 5, September 2014
Pages:
210-216
Received:
25 August 2014
Accepted:
9 September 2014
Published:
30 September 2014
Abstract: The purpose of this paper is to assess the availability and supply of mechanical engineering design and manufacturing infrastructure in Ghana. In the study, the availability of engineering inputs were investigated using a questionnaire administered on suppliers/dealers in engineering inputs, local engineering materials producers as well as machinery design and manufacturing firms in the country. In addition, some amount of data was generated through personal observation. The survey revealed that most of the engineering materials and components available in the country are brought from outside sources as new or used inputs in various forms and sizes; however their quality and specifications are not known. It further revealed that, majority of the suppliers/dealers have very low technical qualifications with a large number of them having no background at all in relevant technical areas. To enhance the supply of machinery infrastructure in the country, government as well as the banks must assist the local industries to produce more of the inputs locally. The Ghana Institution of Engineers and the Ghana Standards Board should regularly organize in-service training for the suppliers/dealers in the country to enable them enhance their competencies and engineering literacy levels.
Abstract: The purpose of this paper is to assess the availability and supply of mechanical engineering design and manufacturing infrastructure in Ghana. In the study, the availability of engineering inputs were investigated using a questionnaire administered on suppliers/dealers in engineering inputs, local engineering materials producers as well as machiner...
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A Reproduction of the Ancient Bandjeli’s Steel-Making Process
Pali Kpelou,
Gnande Djeteli,
Ayi Djifa Hounsi,
Hans Peter Hahn,
Tiburce Ahouangbe Aboki,
Kossi Napo
Issue:
Volume 3, Issue 5, September 2014
Pages:
217-225
Received:
4 September 2014
Accepted:
23 September 2014
Published:
30 September 2014
Abstract: This paper presents an ancient traditional steel-making process of Bandjeli, in the Bassar Region in the Republic of Togo (West Africa). The iron specialists of Bandjeli have owned technical knowledge to cast direct reduced iron (DRI) likely direct reduced steel (DRS). This know-how was transferred to each generation over many centuries. The description of this steel-making process is focused on the steps that lead to the iron ingot: the construction of the furnace, the raw materials collection and their preparation, the furnace filling and the smelting operation. Microstructures of as-smelted and thermo-mechanical treated samples as well as hardness data are presented. Optical and SEM micrographs indicate a Widmannstätten structure type, comprising of a plates or needles of ferrite or alpha iron (Feα) in light contrast and grains of pearlite (dark contrast). Micro-hardness measurements indicate values ranging from 100 to 700 Hv, this field covers the micro-hardness values of the ferrite and pearlite. Microstructural and mechanical properties of the as-obtained product suggest direct steel processing from Bandjeli’s natural draught furnace. These results are necessary for further investigations on the as-smelted steel and on the contribution of this traditional smelting technology to the iron industry.
Abstract: This paper presents an ancient traditional steel-making process of Bandjeli, in the Bassar Region in the Republic of Togo (West Africa). The iron specialists of Bandjeli have owned technical knowledge to cast direct reduced iron (DRI) likely direct reduced steel (DRS). This know-how was transferred to each generation over many centuries. The descri...
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Thermal Stability of Foils Made of Graphene-Oxide and Graphene-Oxide with Fullerene and their Composites with Methylcarboxy Cellulose and with Beta 1,3/1,6 – D - Glucan
Klouda Karel,
Zemanova Eva,
Friedrichova Romana,
Bradka Stanislav,
Gembalova Lucie
Issue:
Volume 3, Issue 5, September 2014
Pages:
226-245
Received:
29 August 2014
Accepted:
16 September 2014
Published:
30 September 2014
Abstract: This contribution contains data on thermal stability of certain materials whose initial precursor is graphite. Graphite was oxidized separately and in a mixture with fullerene C60. The prepared oxides were processed with vacuum filtration to produce foils and their morphology and thermal stability was described. The graphene oxides reacted with nano-cellulose and β-glucan to produce composites. The prepared composites in the form of foils were tested for thermal stability and further analyzed e.g. by FT-IR, SEM, etc.
Abstract: This contribution contains data on thermal stability of certain materials whose initial precursor is graphite. Graphite was oxidized separately and in a mixture with fullerene C60. The prepared oxides were processed with vacuum filtration to produce foils and their morphology and thermal stability was described. The graphene oxides reacted with nan...
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Crack Initiation and Fatigue Behaviour Evaluation of Ceramic Film Deposited on Ti-6Al-4V Alloy
Md. Shamimur Rahman,
Md. Abdullah Al Mahmood
Issue:
Volume 3, Issue 5, September 2014
Pages:
246-249
Received:
8 August 2014
Accepted:
29 August 2014
Published:
30 September 2014
Abstract: Titanium alloy offers several material properties including strength-to-weight ratio and good fatigue properties. Wear resistance of Titanium alloy is comparatively lower. To improve its wear resistant properties surface treatment must be considered. Hard thin film deposited by PVD technique is well-known to improve the wear resistance. In this study, ceramic film (CrN) was applied to titanium alloy and its effect on the fatigue behavior was investigated. Substrate material for this work was Ti-6Al-4V. As the film hardness, crystal orientation and surface morphology were strongly depended on the bias voltage during the deposition, the ceramic film was deposited by arc ion plating (AIP) method at two different negative bias voltages. Tension-tension fatigue test and tensile test were carried out to investigate the fatigue properties. As the result, the fatigue strength was influenced by the deposition of the ceramic film, especially; the fatigue strength was remarkably decreased by the deposition of the ceramic film at high negative bias voltage compared to the uncoated specimen and the deposition of the ceramic at low negative bias voltage. On the basis of crack initiating behavior during fatigue test and tensile test the difference of the fatigue strength was also investigated.
Abstract: Titanium alloy offers several material properties including strength-to-weight ratio and good fatigue properties. Wear resistance of Titanium alloy is comparatively lower. To improve its wear resistant properties surface treatment must be considered. Hard thin film deposited by PVD technique is well-known to improve the wear resistance. In this stu...
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Effect of Substrate Bias Voltage on Fretting Fatigue Behaviour of CrN Film Deposited on Ti-6Al-4V Alloy
Md. Shamimur Rahman,
Md. Abdullah Al Mahmood
Issue:
Volume 3, Issue 5, September 2014
Pages:
250-253
Received:
8 August 2014
Accepted:
20 August 2014
Published:
30 September 2014
Abstract: A fracture behavior of PVD coated ceramic film deposited on Ti-6Al-4V specimens was evaluated for a fretting fatigue geometry in which specimens were contacted on both sides with pads of the similar material. Behavior against the ceramic film coated specimens was characterized through the determination of fretting fatigue strength up to 107 cycles. Fretting damage of specimen surface was characterized by SEM and surface profilometer. Ceramic film coating has a great effect to improve the fretting fatigue strength. From the experimental results of S-N tests it is clear that until about 106 cycles ceramic coating is effective to improve the fretting fatigue strength. But over 106 cycles the strength is lower than that of uncoated specimens. The enhanced fretting fatigue resistance can be attributed to the improved hardness of ceramic film due to change of bias voltage during the film deposition. It has also been concluded that there is smaller influence of bias voltage on fatigue strength below and about 106 cycles; whereas, over 106 cycles, fatigue strength is clearly changed by bias voltage as well as the contact pressure.
Abstract: A fracture behavior of PVD coated ceramic film deposited on Ti-6Al-4V specimens was evaluated for a fretting fatigue geometry in which specimens were contacted on both sides with pads of the similar material. Behavior against the ceramic film coated specimens was characterized through the determination of fretting fatigue strength up to 107 cycles....
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Effect of Reflow Profile Parameters on Surface Mount Chip Resistor Solder Joint Shear Strength
Peter K. Bernasko,
Sabuj Mallik,
G. Takyi
Issue:
Volume 3, Issue 5, September 2014
Pages:
254-259
Received:
10 August 2014
Accepted:
30 August 2014
Published:
30 September 2014
Abstract: The focus of this study is on the effect of reflow parameters on the joint shear strength. Eight reflow profiles were developed using four factors at two levels of Taguchi design of experiment for 1206, 0805 and 0603 chip resistors. Normal probability and main effect plots were used to provide a complete profile of the effect of reflow parameters on the chip resistor solder joint shear strength. The Normal Probability plots show effect of some reflow parameters on shear strength. Some data points did not fall on the best fit line.These outliers indicate parameter effects. The 1206 chip resistor shear strength value of 74.85N lies outside the best fit line indicating that some of the parameters are critical and significantly affect the response value. The results of the Main Effect plots help identify the unknown critical parameters in the probability plots. It indicates that the shear strength of 1206 chip resistor depends on the peak temperature, time above liquidus and preheat slope but not on cooling rate. In the case of the 0805 chip resistor, there were no exceptional departures from the line fitted to the data. It can be assumed that the factors and the levels considered here have no significant effect on the response. The normal probability plot of the 0603 chip resistor shows that the 46.68N shear strength lies outside the fitted line. This means that the factors and settings (run 3) can be further modified to improve the response. The factors which affected the 0603 resistor from the main effect plot are preheat slop and cooling rate.The results of the 1206 chip resistor show the highest shear force of 74.8 N using a peak temperature setting of 230°C (low level). The 0805 and 0603 chip resistors recorded the highest shear forces of 68.32N and 46.48 respectively using a temperature of 245°C (high level). The higher temperature may have contributed to the lower shear force due to the growth of brittle intermetallic compound in the case of the 0805 and 0603 chip resistors.
Abstract: The focus of this study is on the effect of reflow parameters on the joint shear strength. Eight reflow profiles were developed using four factors at two levels of Taguchi design of experiment for 1206, 0805 and 0603 chip resistors. Normal probability and main effect plots were used to provide a complete profile of the effect of reflow parameters o...
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Mechanical Properties of Zirconia-Titanium Composites
Issue:
Volume 3, Issue 5, September 2014
Pages:
260-267
Received:
19 September 2014
Accepted:
25 September 2014
Published:
30 September 2014
Abstract: This study aims to investigate mechanical properties of ZrO2-Ti composites. The samples have been fabricated by spark plasma sintering (SPS). The experimental results demonstrate that a small amount of ZrO2 can enhance Ti matrix in hardness and tensile strength, while a large amount of ZrO2 degrade the tensile strength and ductility because of high extent of formation of titanium oxide. The mechanical properties of ZrO2-Ti composites can be related to thermo-mechanical behavior of ZrO2/Ti functionally graded materials (FGMs). In the FGMs, titanium oxide has also formed, which can largely influence thermo-mechanical behavior of the FGMs.
Abstract: This study aims to investigate mechanical properties of ZrO2-Ti composites. The samples have been fabricated by spark plasma sintering (SPS). The experimental results demonstrate that a small amount of ZrO2 can enhance Ti matrix in hardness and tensile strength, while a large amount of ZrO2 degrade the tensile strength and ductility because of high...
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Electronic and Magnetic Properties of Graphene Möbius Strips: Density Functional Theory Approach
Hossein Mazidabadi,
Hamidreza Simchi,
Mahdi Esmaeilzadeh
Issue:
Volume 3, Issue 5, September 2014
Pages:
268-273
Received:
26 July 2014
Accepted:
12 August 2014
Published:
30 September 2014
Abstract: Electronic and magnetic properties of graphene Möbius strips with different widths are studied using density functional theory. It is shown that the multiplicity of the Möbius strip, the cohesive energy, and the band gap energy increase with increasing the width of Möbius strip. We show that the magnetic moment of Möbius strip decreases with increasing the curvature and strain. Then the effects of an external electric field applied in the direction of the Möbius strip axis are studied and it is found that the Möbius strip keeps its metallic surface (edge) states even in the presence of the electric field. For sufficiently high applied electric field, the spin-flipping can take place in the Möbius strip. In addition, in contrast with the graphene nanoribbons, the graphene Möbius strips show half-semiconducting properties when an external electric field is applied.
Abstract: Electronic and magnetic properties of graphene Möbius strips with different widths are studied using density functional theory. It is shown that the multiplicity of the Möbius strip, the cohesive energy, and the band gap energy increase with increasing the width of Möbius strip. We show that the magnetic moment of Möbius strip decreases with increa...
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A Theoretical Study of the Heavy and Light Hole Properties of Cd1-xZnxS Quantum Dot Superlattices
Saber Marzougui,
Nabil Safta
Issue:
Volume 3, Issue 5, September 2014
Pages:
274-278
Received:
27 August 2014
Accepted:
11 September 2014
Published:
30 September 2014
Abstract: This work reports on a theoretical investigation of superlattices based on Cd1-xZnxS quantum dots embedded in an insulating material. This system, considered as a series of flattened cylindrical quantum dots with a finite barrier at the boundary, is studied using the tight binding approximation. The ground miniband width and the longitudinal effective mass, in the case of the heavy and light holes, have been computed as a function of zinc composition for different inter-quantum dot separations. An analysis of the results shows that the Zn composition x = 0.8 are appropriate to give rise a superlattice behavior for the light holes. As for the heavy holes, it has been showed the strong localization character of theses carriers in the Cd1-xZnxS nanostructures.
Abstract: This work reports on a theoretical investigation of superlattices based on Cd1-xZnxS quantum dots embedded in an insulating material. This system, considered as a series of flattened cylindrical quantum dots with a finite barrier at the boundary, is studied using the tight binding approximation. The ground miniband width and the longitudinal effect...
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