bluuebunny/crossref_metadata_2025 huggingface dataset:
Rotational Rheology of A356 Semi-Solid Alloy at Low Solid Fractions
Authors: Jabbari Amin , Sadough Seyedali Ali , Pouyafar Vahid
Published: October 2014

The main goal of investigations on semi-solid metal processing is to produce complex parts with enhanced mechanical properties. Flow behavior and die filling in semi-solid processing is an intrest area of researchers. A comprehensive understanding of the behavior of the under investigation metallic slurry is the design key of a successful manufacturing process. In this way the material’s transient response is very important for understanding of the rheological properties and also further commercial development of the process. The material used in this research is an Al-Si alloy which is widely used in automotive and aerospace applications. The experiments were conducted using a Searl rheometer which is specially designed for high temperature rheological measurements. For rheological tests of semi-solid alloy in different solid fractions, the isothermal holding and shear rate step change experiments were examined. Using practical rheological results, a single phase thixotropic model has been derived and adopted with measurements. The investigated alloy behavior was obviously thixotropic which is quantified in a theoretic model. Also instantaneous rheopectic behavior was observed for this alloy. The state of the microstructure has been applied through a structural parameter. The presented model for A356 alloy fits well with the experiments.
Microstructure Evolution in Melt Conditioned Direct Chill (MC-DC) Casting of Fe-Rich Al-Alloy
Authors: Kotadia H.R. , Patel J.B. , Li H Tian , Gao F. , Fan Z.
Published: October 2014

In order to fabricate high quality aluminium products, it is first essential to produce high quality billets/slabs. One of the key objectives associated with casting processes is to be able to control the as-cast structure. A novel direct chill (DC) casting process, the melt conditioned direct chill (MC-DC) casting process, has been developed for production of high quality aluminium billets. In the MC-DC casting process, a high shear device is submerged in the sump of the DC mould to provide intensive melt shearing, which in turn, disperses potential nucleation particles, creates a macroscopic melt flow to uniformly distribute the dispersed particles, and maintains a uniform temperature and chemical composition throughout the melt in the sump. The effect of intensive shearing on the complex microstructure evolution observed after MC-DC is explained on the basis of nucleation and growth behavior. Complete suppression of typical columnar grain growth and significant equiaxed grain refinement is observed. The solidification mechanisms responsible for the significant grain refinement by intensive shearing and the morphological evolution of Mg2Si and Fe–containing intermetallic phases are discussed.
Research on Elastic-Plastic Transition and Hardening Effect for Monocrystalline Silicon Surfaces
Authors: Guo Xiao Guang , Zhai Chang Heng , Liu Zi Yuan , Zhang Liang , Jin Zhu Ji , Kang Ren Ke
Published: October 2014

Based on molecular dynamics method, a nanoindentation simulation of the silicon crystal is built and the load-displacement curve is drawn. According to the load-displacement curve, the elastic-plastic transition of silicon crystal is analyzed. The results show that the critical point in the elastic-plastic transition is between 15 and 20 angstroms. In addition, different crystal planes of silicon crystal are loaded for five cycles respectively; the nanohardness is calculated and the nanohardness curve is obtained. The results show that after the first plastic deformation of the silicon crystal surface is occurred, the surface will have a higher hardness and a higher elasticity. Therefore, in the ultra precision machining, in order to reduce the occurrence of damage, the depth of the processing should be controlled in the range of elasticity. Moreover, the method of small quantities in high frequency can increase mechanical properties on the surface.
Simulation of Ground Surface Residual Stress for Surface Integrity in Small Depth of Cut
Authors: Zhang Xiu Ming , Liu Li Juan , Xiu Shi Chao
Published: October 2014

The surface residual stress and integrity of workpiece have significant effects on the precision, the reliability and the fatigue life of the mechanical products. Since the most final surface integrity of workpiece depends on the grinding process mainly in engineering, this paper analyzed the surface residual stress of ground surface through the simulation works. Based on the finite element model and the thermal mechanical coupling field of the surface grinding for 45 steel was simulated and analyzed. The distribution of the residual stress and the effects of grinding parameters on residual stress were discussed. In addition, the measures for improving the residual stress in ground surface were put forward.
Influence of Grinding Parameters on Residual Stress of Nano-ZrO2 Ceramics
Authors: Zhao Ming Li , Guo Qiu Chen , Zhao Bo
Published: October 2014

Residual stress of ceramics ground surface was detected by the X-ray instrument, and it was analyzed in present paper. The experimental results show that the content of metastable tetragonal phase of ZrO2 and grinding stress are the primary factors which induce martensitic transformation on ZrO2 ceramics ground surface; during grinding the deeper the grinding depth is, and the bigger abrasive grain size is, the grinding stress in material matrix is larger. After analyzing the influence of grinding parameters on residual stress, it can be found that martensitic transformation can prompt the compressive residual stress to some extent, so as to improve the quality of ground surface.
Study on the Effect of Vibration Amplitude in Two-Dimension Ultrasonic Vibration Cutting
Authors: Niu Ying , Jiao Feng , Li Jie , Zhang Jia Fei
Published: October 2014

Longitudinal-bending complex vibration can be realized by opening chute on the amplitude amplifier pole. Different longitudinal and bending amplitudes can be obtained under different angles and the number of the chutes. Based on the theory of two-dimensional ultrasonic cutting, the effects of the two dimensional amplitude on the cutting characteristics were analyzed experimentally in the paper. Research results show that the amplitudes of longitudinal and bending vibration have a great effect on cutting force and machining quality in two-dimensional ultrasonic vibration cutting of hard and brittle materials. When keeping constant longitudinal amplitude and increasing bending amplitude in a certain extent, the cutting force could be reduced and the machining quality of workpiece could be improved effectively. The research provides relevant basis for designing two-dimensional longitudinal bending vibration cutting system.
Investigation of Surface Integrity on TC4-DT in High Speed Grinding with CBN Wheel
Authors: Chen Yao Guang , Lu Wen Zhuang , Xu Jun , Zhu Yan Song , Zuo Dun Wen
Published: October 2014

A series of grinding experiments were carried out with CBN wheel to focus on the surface integrity of titanium alloy TC4-DT in high speed grinding . In order to get the proper process parameters to control the surface integrity of the TC4-DT, surface roughness, subsurface morphology and microhardness variations have been studied. In addition to the use of CBN wheel, scanning electron microscopy (SEM), 3-d contour instrument and microhardness tester was applied. The results show that the surface roughness is decreased obviously when grinding wheel linear velocity rises from 60m/s to 80m/s. While the grinding speed rises from 80m/s to 100m/s, the surface roughness value increases slightly. Moreover, the surface roughness value increases with the grinding depth and the increasing trend is obvious in the process of machining. The microstructure analysis shows that during high speed grinding with CBN wheels, good quality surface with 10μm grinding depth can be obtained. Table feed rate has weak influence on the grinding surface topography. The microhardness analysis indicates that surface microhardness increases sharply with the increasing of grinding wheel linear velocity in high speed grinding.
Simulation of Temperature Distribution in HFCVD Diamond Films Growth on the Multitudinous Micro End Mills
Authors: Song Bo , Shen Bin , Lei Xue Lin , Cheng Lei , Sun Fang Hong
Published: October 2014

In the process of HFCVD diamond film growth on the multitudinous micro end mills, the uniformity and stability of the temperature distribution have a vital importance on the quality of film. So a new method by using the finite volume is proposed to analyze the importance of different disposition parameters on the uniformity of substrate temperature field. These parameters are filament diameter (d), filament-substrate distance (H), filament separation (S) and filament length (L). The mono-factor method are used to optimize the best parameter combination. The simulation results show that the optimized parameters are d=0.65mm, H=10mm, S=27mm and L=160mm.
Comparison of Fe Catalyst Species in Chemical Mechanical Polishing Based on Fenton Reaction for SiC Wafer
Authors: Wang Lei , Yan Qiu Sheng , Lu Jia Bin , Xiao Xiao Lan
Published: October 2014

Chemical reaction rate of SiC wafer surface usually determines the material removal rate (MRR) in chemical mechanical polishing (CMP). In this paper, systemic experiments are carried out to discover the relationship between Fe catalyst with different forms or valence and chemical reaction rate based on Fenton reaction. Experimental results show that the MRR changes little using Fe powder or hydrogen peroxide (H2O2) alone, but the MRR of SiC will increase largely by adding them both that will produce Fenton reaction. The MRR continues to increase slightly when Fe2+ ions is employ as catalyst, but that is much lower when utilizing Fe3+ ions. Moreover, SiC wafer with a smaller surface roughness and better quality can be obtained when using Fe powder as catalyst in Fenton reaction. The results indicate that the Fenton reaction can effectively improve the polishing efficiency of SiC substrate and Fe powder is more suitable for polishing of SiC than ferrous or ferric salt in CMP based on Fenton reaction.
The Optimization of Termination in Combined Technique of Magnetorheological Finishing and HF Etching for Laser-Induced Damage Threshold High-Efficiency Improving of Fused Silica
Authors: Tian Ye , Peng Xiao Qiang , Dai Yi Fan , Shi Feng , Wan Wen
Published: October 2014

The developing high-power laser systems are requiring higher laser-induced damage threshold (LIDT) and fabrication efficiency of fused silica optical elements. To solve these problems, MRF polishing and HF etching have been combined utilized wiping and passivating structural defects as well as removing impurities. Furthermore, the LIDT improvement is dependent greatly on the corporation of processes. But the LIDT improving mechanism is partly ambiguous yet, that may lead to random or experimental parameter choice and ultimately generate unsatisfied results. Consequently, this paper focuses on the termination mechanism of the process. Atom Force Microscope (AFM) measurement, finite difference time-domain (FDTD) simulation and LIDT test will be utilized to analysis and validate the optimization theoretically and practically. Finally, in one side, the LIDT value of optimized-terminated sample is 16.7J/cm2, which is about the same level (even 3.7% higher) as that of the over-etched one. In another side, the etching process time could be shorted by 32% using the optimized method.
Formation and Simulation of Negative Shear Zone
Authors: Qu Hai Jun , Yang J.H. , Wang Gui Cheng
Published: October 2014

Cutting-direction burr/fracture is one of the important factors that influence the edge quality and performance of precision parts.The formation of negative shear zone decisions the edge quality of workpiece. A finite element model has been established to investigate the mechanism of negative formation in machining H64 brass. The negative shear zone formation process is simulated with rigid-plastic nonlinear finite element method. The cutting direction burr forms when the stress of principal shear zone great than it in negative, the cutting direction fracture forms when the stress of principal shear zone less than it in negative and there is a crack in the area near the tool tip and grow along the negative shear zone .
Fe Based Amorphous Alloy Used for Catalytic Machining Diamond Film
Authors: Shi Shuang Ji , Lin Jia Zhi , Jin Zhu Ji , Zhong Xiu Hong , Yin Bo
Published: October 2014

Diamond is a kind of ultra-hard and difficult-to-machine material. By means of the graphitization of diamond, dynamic friction polishing (DFP) technology is used to achieve a high-efficiency material removal of diamond. The polishing plate of DFP plays a key role in the process of polishing, and catalytic metal with unpaired d electrons is considered as ideal polishing material. To discuss and verify the feasibility that amorphous alloy can be used to polish CVD diamond film by DFP, Fe based amorphous alloy was prepared by mechanical alloying method and spark plasma sintering technology. The results showed that diamond film got a higher removal and a better polishing effect. This work provided a new selection for the polishing plate used for DFP of diamond.
Detection and Analysis of Subsurface Cracks of Single Crystal SiC Wafers Based on Cross-Sectional Microscopy Method
Authors: Yan Qiu Sheng , Chen Sen Kai , Pan Ji Sheng
Published: October 2014

For subsurface crack detection of single crystal SiC wafer, this paper proposed a cross-sectional cleavage detection method and compared with traditional cross-sectional sample preparation method. The characteristics and detection results of two cross-sectional sample preparation methods were compared and the subsurface crack characteristics in SiC wafer grinding were researched. The results show that the configurations and depth of subsurface cracks measured by two cross-sectional sample preparation methods were similar. The cross-sectional cleavage sample preparation method is simpler and more rapid in subsurface crack detection. The subsurface crack system of single crystal SiC wafer grinding mainly includes lateral crack and median crack.
Structure Simulation and Performance Test of Flexible Fixture Based on Magneto-Rheological Fluids
Authors: Ma Jun Jin , Zhang Ding Hua , Wu Bao Hai , Luo Ming
Published: October 2014

To solve the precision manufacturing of thin-walled irregular-shaped workpiece, the MR fluids flexible fixture was designed and the simulation of device with compression structure was carried out to obtain performance parameters of device for optimizing the device. Then, some experimental test was implemented to verify the feasibility of device. The simulation and experimental results show that the current and coil turns have a great influence on magnetic field, and the shear stress of MR fluids are related with magnetic field and external compression force. The experimental results are in good agreement with simulation ones.
Research on Conical Hole Ladder Horn Based on Transmission Matrix Method in Ultrasonic Milling
Authors: Gao Guo Fu , Zhao Jin Zhui , Fu Zong Xia
Published: October 2014

In order to solve the problem of efficient and accurate tool change in vibration system, horn with a conical hole and a center via hole which connects tool is proposed. In connection with the shape of the horn, an equivalent model of the horn is built up. Based on the transmission matrix method, the frequency equation and magnification factor of the horn is deduced. And the finite element method was employed to verify the derived formulas. Compared the simulation results with the theoretical results, the derived formulas can be applied to design the complex horn.
The Study of the Processing Method of Room Temperature Vulcanized Silicone Rubber (RTV) on the Surface of the Locomotive Bearing Seal Rings
Authors: Zhang Hong You , Zhang Yong Chun , Wu Ming Yu
Published: October 2014

The experimental research is confirmed the method about the residual room temperature vulcanized Silicone Rubber (RTV) on the surface of the locomotive bearings after dismantling. The Alkaline inorganic solution has no actual effect on the RTV soaking. While the carbinol and xylene organic solution have alittle effect of dissolving for the RTV on the locomotive bearing seal rings, and both reduce elasticity and function of the seal rings. After long time soaking with the acetonum solution and polishing by hand, It can clean up all the RTV, and the seal ring has no effect on it.
Drill Rod Lateral Vibration Mechanics during Mining Horizontal Drilling for Gas Drainage
Authors: Han Xiao Ming , Li Dong Sheng , Zhang Long Lie , Han Xing Yu
Published: October 2014

Through the condition analysis of the drill rod during the mining horizontal drilling for gas drainage, the finite element model of the drill rod lateral vibration is established. The drill rod lateral vibration is related to the diameter and length of the drill rod. With the increase of the diameter of the drill rod, the natural frequency of the lateral vibration of the drill rod increases constantly. The increasing amplitude of the natural frequency at the larger diameter of the drill rod is larger than that at the smaller diameter. When the drill rod is longer, the natural frequency of the lateral vibration of the drill rod is lower. From the modal images of the drill rod, the lateral vibration of the drill rod is similar to the sine curve. During the horizontal drilling in coal seam, the drill rod contact and impact with the hole wall which will bring about the fatigue fault of the drill rod and the collapse of the hole wall.
Experimental Study on the Wireless Transmission System in the Ultrasonic Milling
Authors: Li Zhang Dong , Zhao Bo
Published: October 2014

One-dimensional tool ultrasonic vibration system was designed and manufactured, and the influence law of air gap, axis deviation, axis deflection on the coupling coefficient and the transmission efficiency were studied.The influence of the cross-sectional area, air gap and axis deflection angle on the coupling coefficient and transmission efficiency are very obvious, so must be paid special attention in the design and installation.
Vibration Monitoring System Design
Authors: Li Wen Xing , Jia Meng
Published: October 2014

Along with the computer software technology, the virtual instrument is gradually become the development direction of the test area. The realizing vibration test which is analyzed by adopting the virtual instrument has become the development trend of vibration test. It firstly introduces relevant simulation technology theory, the principle of fault diagnosis, the significance and the development present situation. Then according to the research for the development current situation of condition monitoring and fault diagnosis at home and abroad, it puts forward the vibration test analysis system composed the necessary sensors, signal disposal device and data acquisition card. At last it uses labwindows software produced in NI to do the development platform.
Hydrogel Scaffold Fabricated by 3D Printing & Ultrasonic Spraying
Authors: Li Yu , Bian Ping Yan
Published: October 2014

This paper presents a novel strategy for fabricating hydrogel scaffold at ambient temperature by 3D printing supplemented with an ultrasonic spraying which involves crosslink reaction. The contradictory between the rheological properties and solidification of natural biological material for machinability and formability respectively at ambient temperature was solved. The gelled fraction and porosity were measured respectively to study the influence of crosslinking agent. The results showed that the two subjects appear a parabolic trend with the concentration of CaCl2 from 2% to 4%, but the tolerance of aperture decreases monotone.
The Study of the CBN Grain Shape on its Microcutting Performance Based on Finite Element Method
Authors: Zhi Geng , Bi Wei Yao , Tang Jia Jun , Li Xue Kun , Rong Yi Ming
Published: October 2014

Given that the grain geometry has an important impact on grinding process, it’s necessary to investigate the influence of grain shapes on grinding mechanism. In this paper, a 3D FEM model is developed to study the effects of CBN grain geometry on its microcutting performance under various speed levels, which is effective to understand the microcutting process qualitatively and quantitatively. The simulation results indicate that the single grain microcutting force ratio and material removal ratio are both sensitive to the grain shape and those grains with truncated tetrahedron shape of large cross-sectional area and negative rake angle would improve the cutting performance.
The Research and Development on the Material Removal Mechanism of the Ultrasonic Cutting
Authors: Lou Yan Yan , Zhang Yan , Gao Ying , Zhang Jia Chen , Sun Yan Zhou
Published: October 2014

Ultrasonic machining is an important part of modern processing technology which is adapt to all kinds of hard brittle materials processing. This paper reviews the latest progress of the material removal mechanism on one-dimensional ultrasonic machining, two-dimensional ultrasonic machining and rotary ultrasonic machining, and expounds the development trend of establishing the material removal model of the ultrasonic machining.
Study on Process Parameters in CMP Ultra-Thin Stainless Steel Sheet
Authors: Cheng Hai Feng , Ma Li Jie , Yao Jian Guo , Su Jian Xiu
Published: October 2014

Chemical mechanical polishing (CMP) is the most effective technology to achieve ultra-smooth without damage surface in ultra-precision machining of stainless steel substrate. In this paper, according to the slurry ingredients obtained by former research, the influences of the CMP process parameters, such as the rotational velocity of the platen and the carrier, the polishing pressure and the abrasive size on the material removal rate (MRR), have been studied in CMP stainless steel substrate based on the alumina (Al2O3) abrasive. The research results show that the material removal rate increases with the increase of the abrasive size, the rotational velocity of the platen and the polishing pressure significantly and the surface roughness increases with the increase of the abrasive size. This study results will provide the reference for optimizing the process parameters and researching the material removal mechanism in CMP stainless steel sheet.
Optimization of Milling Parameters of CFRP for Surface Roughness Using Taguchi Design Method
Authors: Zhou Jing Wen , Chen Yan , Fu Yu Can , Xu Jiu Hua , Hu An Dong , Liu Si Qi
Published: October 2014

End milling is conducted on carbon fiber reinforced plastics (CFRP) by using a diamond coated cemented carbide tool. Taguchi design method is employed to investigate the influence of cutting speed, feed rate and depth of cut on surface roughness. In Taguchi method, a three level orthogonal array has been used to determine the S/N ratio. Analysis of variance (ANOVA) and pareto diagram are used to determine the most significant milling parameters affecting the surface roughness. The results indicate that only the depth of cut has great statistical significance on the surface roughness, while the influences of cutting speed and feed are negligible. SEM micrographs shows that with the increase of depth of cut, a great deal epoxy resin will adhere to the finished surface. The greatest S/N ratio (1.46dB) is obtained during the validation experiment with optimum milling parameters.
Oxidant for Chemical Mechanical Polishing of Single Crystal Diamond
Authors: Shi Zhuo Ying , Jin Zhu Ji , Xue Hong Ming , Shi Shuang Ji
Published: October 2014

Single crystal diamond is widely used in high-tech fields for its remarkable performance on mechanics, calorifics, optics, acoustics, etc. High-quality diamond surface with small roughness and low scathe are required in these applications. However, the extreme hardness and high chemical inertness of diamond result in severe processing difficulties. Chemical mechanical polishing (CMP) is a promising processing method which can obtain super-smooth and low-damage diamond surface. Oxidant is a key issue for CMP of single crystal diamond. In this study, five different oxidants were used to polish diamond samples. The results indicated that Fenton reagent was an appropriate CMP oxidant and a super-smooth diamond surface of Ra 2.4 nm was achieved by using Fenton reagent in CMP.
Electroless Deposition of Copper Nanostructures in Aqueous Solution
Authors: Tan Michael , de Jesus Lance , Amores Kathy Lois , Datu Ellaine , Balela Mary Donnabelle
Published: October 2014

This paper reports a simple and low cost process for the synthesis of various Cu nanostructures by electroless deposition. Oxidation-stable Cu nanoparticles and nanowires were prepared in aqueous solution in the presence of protective agents. When gelatin is used as protective agent, only spherical Cu nanoparticles with a mean diameter in the range of 37 to 44 nm are formed in the solution. Smaller nanoparticles are prepared at a higher concentration of gelatin. When ethylene diamine is used instead of gelatin, one-dimensional growth of Cu nanowires is favored. Varying the amount of EDA and gelatin provides morphological control over the nanostructures.
Glass Ceramization as an Alternative Production Route of Forsterite Glass-Ceramics for Possible Multipurpose Uses
Authors: Aboud Taufik
Published: October 2014

Homogenous, transparent and bubble-free glass was produced through the addition of an extra silica as a replacement for its structurally analogous AlPO4in an aluminophosphosilicate base glass. FT-IR, DSC, XRD and SEM coupled with EDX, were all used to characterize the obtained glass, and to establish the effect of silica as a substitution for AlPO4on the vibrational spectra and crystallization behavior of the obtained glass.Silica was found to lower the wavenumber of the main stretching vibrational band of aluminophosphosilicate glass, thus counterbalancing the increment in the wavenumber of the main stretching band caused by P2O5in the former base glass. The obtained glass crystallized in bulk at relatively low temperatures, and the first phase to crystallize was enstatite. As temperature was increased, both enstatite and forsterite coexisted. At yet higher temperatures, forsterite was the predominantly crystallizing phase with just traces of enstatite.Thus, it is believed that glass ceramization represents a challenging and yet a promising fabrication route with many technological advantages, over other making techniques, such as sol-gel and solid-state or solid solution routes, for production of forsterite-enstatite and forsterite ceramics. The obtained glass-ceramics are possible candidates for advanced applications, utilizing properties of forsterite, such as bioactivity, dielectricity and birefringence, among many others.
The Breakdown of Carbide Network in a H23 Tool Steel by Hot Axisymmetric Compression
Authors: Nurbanasari Meilinda , Tsakiropoulos Panos , Palmiere Eric J.
Published: October 2014

The effects of hot axisymmetric compression to break down the primary carbide network of the H23 tool steels were studied. This current study only focused on one strain rate of 0.01 s-1. The samples were deformed at 3 different temperatures (1000, 1050 and 1100 °C) with solutioning temperatures 1100 and 1250 °C, respectively. Afterwards, the samples were cooled by water quenching. The techniques used in this current study for investigation were the optical and electron microscopes and Vickers hardness test. The results show that hot axisymmetric compression had broken down the primary carbide network in the direction perpendicular to the compression axis and the carbides became finer. Although the highest hardness (274 HV) was achieved after solutioning at 1250 °C, followed by deformation at 1000 °C, however the microstructure analysis indicated that the optimum hot axisymmetric compression condition was solutioning at 1250 °C and deformation at 1000 °C.
In Situ Deposition of Conducting Polymer onto Pineapple Leaf Fiber
Authors: Abd Razak Saiful Izwan , Ahmad Sharif Noor Fadzliana , Mat Nayan Nadirul Hasraf , Muhamad Ida Idayu
Published: October 2014

This paper reports the properties of newly developed electrically conductive natural fiber made up of pineapple leaf fiber (PALF) and conducting polyaniline (PANI). The results revealed that the in situ coating of PANI (1 wt.%) showed minimal reduction on the PALF tensile strength. Percolation concentration of the PANI was observed at 5 wt.% and its corresponding electron micrograph showed good polymer deposition with the characteristic globular PANI formation plus no fiber damages. This fiber material has potentials for many applications such as composites, electroactive fillers and conductive sheets.
Mangrove Tannin (Rhizophora apiculata) Complexes with Copper (II) Ion as an Antifoulant in Antifouling Paint for Fish Net
Authors: Achmad Azraa , Kassim Jain , Ghafli Azwin Usol , Hamdan Hairul
Published: October 2014

Mangrove tannin was used to be complex with copper (II) ion. The optimum condition of copper tannate complex was studied using four parameters which were copper dosage, pH solution, temperature and time. The copper tannate complex was characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX) and brine shrimp toxicity assay. This study suggested that copper tannate complex has a great potential to be develop as an alternative antifoulant.
Zinc Oxide Nanostructures Formed by Wet Oxidation of Zn Foil
Authors: Pelicano Christian Mark , Lockman Zainovia , Balela Mary Donnabelle
Published: October 2014

Zinc oxide (ZnO) nanostructures were successfully grown by wet oxidation of zinc (Zn) foil in water at 90 °C for 2 to 8 h. The effect of etching the Zn foil before oxidation treatment on the morphology of ZnO nanostructures was investigated. Hemispherical structures of ZnO nanowires, nanorods and nanotubes were produced on etched Zn foil at different oxidation times. The growth of hemispherical structures was possibly due to the formation of pits along the grains after etching. Without etching, relatively aligned nanorods were formed after wet oxidation with the structure becoming coarser after longer oxidation time. The anisotropic growth ZnO nanostructures on the surface of Zn foil by wet oxidation could be due to the inherent growth habit of ZnO crystal.
Assessment of Connection Arrangement of Built-Up Cold-Formed Steel Section under Axial Compression
Authors: Muftah Fadhluhartini , Mohd Sani Mohd Syahrul Hisyam , Muda Mohd Fakri , Mohammad Shahrin
Published: October 2014

Cold-formed steel (CFS) with several of the advantages is selected in construction activity as structural and non-structural element. CFS with variety of shape, dimension and grade is chosen to replace traditional material that largely used before. In the study, CFS is utilised as a compression member to support beams element in the building. The column made with CFS is important to sustain the load and build the stable equilibrium circumstances. The column stability is the big issue that must be discussed and determined to prevent the buckling load, unmanageable deflection and lastly building collapse. So that, the study of structural properties and column capacity under compression load of the column is being investigated. Compression test of built up CFS channel that is attached at open side facing by using bolting through the web of the channel. A tensile coupon specimen of channel is taken at the flange and web of CFS channel to find the actual material properties the results that the CFS behave similar to a carbon steel with yield stress 500 MPa. Five arrangement of bolt that are margin of its mid height, compressed using a servo machine to get the axial capacity of the column. Under constant length of 900 mm and constant material, the end distance of bolt to the tip of the column are greatly affecting the column capacity by strengthening its bearing capacity. Hence, it is recommended that, the end distance of bolt must be placed at 20 mm to improve the bearing strength of the column, and the spacing of columns can be restudy for better results.
Development of Grounding Device to Reduce Current Variation in Submerged Arc Welding Process for Pressure Vessel Fabrication
Authors: Rajsiri Supphachan , Penpondee Kanokporn , Tuntawiroon Sittiphun
Published: October 2014

This study developed a device to solve welding problems that occur in the manufacturing of a pressure vessel for cryogenic applications under the ASME Section VIII Division 1. The cylindrical body of the vessel was assembled with short pre-fabricated cylinders and caps using submerged arc welding. The rotatable grounding electrode was mounted to the top half of the spherical cap. However, the relatively long distance between the welding and the electrode grounding locations, especially in longer vessels, restricts the flow and the distribution of the electrical current. Radiographic testing identified lack of fusion as the major reason for the restricted flow of the electrical current. This also caused additional work on welding repair. To address this issue that compromised both top-outer and bottom-inner vertical positions for circumference welding, a new grounding device was developed to reduce the flow distance. The electrical conductivity was also improved through a series of welding tests. The investigation showed that a greater average welding current increased arc stability. Radiographic testing confirmed that the vessels were welded completely suggesting the grounding device utility for increasing welding joint soundness of the circumference weldment.
Effect of CNT Arrays on Electrical and Thermal Conductivity of Epoxy Resins
Authors: Wu Liang Ke , Ying Ji
Published: October 2014

With the development of electronic technology, thermal interface materials (TIMs) of excellent thermal conductivity have been desired for circuit integration. In this study, carbon nanotube arrays (CNTAs) were utilized to prepare high thermal conductive composites by infiltration into epoxy resin. The composite was cured in a drying oven at 60 °C for 4 h. The thermal conductivity of the composite along axial direction reaches 2.24 W/mK at 120 oC, which is about 10 times of that of pure epoxy resin. The results indicated that the great promise of epoxy/CNTA composites as thermal interface materials. However, the electrical conductivity still remains at a low level, although it is increased by orders of magnitudes, the insulativity is beneficial for the application of this composite in electrical industry.
Nano-Yttrium Aluminium Garnet Interfacial Tension and Viscosity for Enhanced Oil Recovery
Authors: Lee Kean Chuan , Yahya Noorhana , Che Yaccob Siti Najwa , Guan Beh Hoe
Published: October 2014

This paper describes the synthesis of Yttrium Aluminum Garnet (YAG), Y3Al5O12 nanoparticles (NPs) and their application in Enhanced Oil Recovery (EOR). YAG NPs were synthesized by using sol-gel method. These NPs were then synthesized by using Thermal Gravimetric Analysis (TGA), X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM). The monophasic YAG having crystallites size of 40.98 nm and 40.91 nm were obtained at annealed temperature of 1100 °C and 1200 °C as determined by XRD. Magnetic measurement results show that initial permeability of YAG increased and relative loss factor decreased at high frequency. In this paper, the feasibility of application of YAG nanofluid in EOR was determined by measuring oil-nanofluid interfacial tension and also viscosity of the nanofluid. YAG with 0.5 wt% yielded the lowest IFT. It can be concluded that the synthesized YAG nanoparticle has great potential in EOR applications in the near future.
Investigation on Microstructure and Mechanical Properties of Squeeze Cast Al-Si Alloys by Numerical Simulation
Authors: Kiaee Mona , Sulaiman Shamsuddin , Tang Sai Hong , Mohammadi Mohammad Ali
Published: October 2014

Since squeeze casting process is considered as a new technology for light alloys like aluminum and magnesium, more basic research is required for a scientific understanding of the practice. In distinct, as a cost-effective and resource-efficient tool, advanced numerical modelling in conjunction with dynamic boundary conditions and capabilities of predicting the formation of casting defects have to be fully developed for the optimization of squeeze casting processes. In squeeze casting, an external pressure is applied to molten metal before, during and after its solidification, which makes the condition at the casting die interface different from other typical casting techniques. In this paper, Finite Difference Method (FDM) is used to investigate the effect of heat transfer during squeeze casting process and the relationship between casting temperature and solidification on Al-Si alloys.
Solid Particle Erosion Behaviour of Martensitic and Nitrogen Alloyed Austenitic Stainless Steel
Authors: Selokar Ashish , Kant Ravi , Goel D.B. , Prakash U.
Published: October 2014

In the present work, comparison of solid particle erosive behaviour of 13/4 steel and Nitrogen alloyed austenitic stainless steel (23/8N steel) have been studied using air jet erosion testing. Air jet erosion testing has been performed at various angles for as received samples at 31 m/s velocity and a discharge rate of 3 gm per minute by alumina particles with angular shape and 53-63μm size. Microstructure, eroded surface characteristics, mechanical properties and erosion rate are characterized by using scanning electron microscope, hardness and tensile testing. 23/8N steel shows good hardness coupled with high tensile toughness and work hardening ability, which leads to improved erosion resistance. The surface morphology analysis of the worn out surfaces, cumulative weight loss measurements and steady state of erosion rate results were used to understand the effect of nitrogen on the degradation mechanisms. The results show that 23/8N steel exhibits excellent resistance to erosion in comparison to13/4 steel.
Investigation of Carbon Nanofiber Supported Iron Catalyst Preparation by Deposition Precipitation
Authors: van Thien Duc Nguyen , Sufian Suriati , Mansor Nurlidia , Yahya Noorhana
Published: October 2014

An ammonia synthesis using magnetic field to replace Haber-Bosch’s ammonia production is great technological challenge in novel magnetized catalysts area. The carbon nanofiber supported iron catalyst was prepared by modifying carbon nanofiber support surface and later using urea to precipitate iron nitrate by deposition precipitation. It was found that the particle size was in a range of 5-50nm and well dispersion of iron was shown by transmission electron microscopy. This was strongly influenced by alteration of carbon nanofiber surface from hydrophobic to hydrophilic and with high adsorption sites as oxygen functional groups and defects. The lower iron loading between 5 and 40%wt, the lower iron accumulation and the narrower the particle size distribution of 10-20nm. The result suggests that the iron particles are in a good size range for iron catalyst activity for ammonia synthesis as reported by Morawski et.al and Figurski et.al authors.
Hydrophobic-Synthesis of Bio-Based Epoxy Substrate Using Methyl Ester and its Dust Deposition and Decontamination Effects
Authors: Nasri Noor Shawal , Ahmed Murtala Musa , Shamsu Kamar Amalina Nurhidayah , Sing Tee Yee , Hamza Usman Dadum , Mohammed Jibril , Mohd Zain Husna
Published: October 2014

This research investigated the prospect of using bio-based substrates for dust decontamination purposes. Initially, bio-based novolac resin was prepared by condensation from the reaction between phenol, bio-oil phenolic fractions and formaldehyde in an acidic medium. The prepared novolac was later transformed to epoxide with epichlorohydrine and 30 percent sodium hydroxide solution. The epoxy formulation was later enhanced with varying amount of methyl ester (10 wt%, 20wt% and 30wt% ). The samples were characterised using various techniques such as FTIR, GC-MS, contact angle etc. Dust depositions and decontaminations tests were also conducted. The results indicated that the synthesized hydrophobic bio-based sample possed some dust cleaning characteristics which when fully enhanced would lead to the emergence of bio-based dust cleaning formulation will contribute immensely in mitigating the negative effect and toxicity of petroleum based products.
Recycling of Pre-Fabricated Carbon-Fiber Waste as Filler for Sandwich Glass-Fiber Auto Parts
Authors: Yamkamon Pongpicha , Sritrakulchai Kiattisak , Rajsiri Supphachan
Published: October 2014

This study explored the possibility of recycling pre-fabricated carbon to use as filler in conjunction with talc to produce glass-fiber reinforced unsaturated polyester composites. Specimens with six different resin compositions were prepared using hand lay-up technique. The structure and property relationship was characterized through tensile test and microstructure analysis. Mechanical properties incorporated with the failure analysis suggest that the recycling of carbon is feasible. The application of the recycled carbon showed the improvement on the less variation on the mechanical properties. The percent elongation at break tended to reduce, and traded-off with the deterioration on tensile strength at break and elastic modulus. Mixing with 10-15 wt% recycled carbon and 5-10 wt% talc powder was suggested to yield the optimal tensile properties. Moreover, the recycled carbon previously coated with unsaturated polyester guides the uniform distribution when required to process with a high-polarity material by reducing the polarity effect.
Fabrication of ZnO Nanorod for Room Temperature NO Gas Sensor
Authors: Tan Sin Tee , Yahaya Muhammad , Tan Chun Hui , Yap Chi Chin , Ali Umar Akrajas , Mat Salleh Muhammad
Published: October 2014

One dimensional ZnO nanorod has been extensively studied in sensor application due to its unique properties in direct energy band gap and high binding energy. In this report, ZnO nanorod arrays were synthesized via hydrothermal approach. Highly oriented (002) nanorods array with diameter of (22.42 ± 1.40) nm was successfully grown on the quartz surface. A low cost and room temperature optical based NO sensor was introduced. ZnO nanorods array show a high sensitivity upon the NO gas which is 20.1 % within 3 minutes. This newly established method can be potentially used in detection of other toxicity gas.
Analysis of Thermal Conductivity of LaFeAsO at Low Temperature
Authors: Kaurav Netram , Choudhary K.K.
Published: October 2014

Thermal conductivity κ (T) of LaFeAsO is theoretically investigated below the spin density wave (SDW) anomaly. The lattice contribution to the thermal conductivity (κph) is discussed within the Debye-type relaxation rate approximation in terms of the acoustic phonon frequency and relaxation time below 150 K. The theory is formulated when heat transfer is limited by the scattering of phonons from defects, grain boundaries, charge carriers, and phonons. The lattice thermal conductivity dominates in LaFeAsO and is an artifact of strong phonon-impurity and-phonon scattering mechanism. Our result indicates that the maximum contribution comes from phonon scatters and various thermal scattering mechanisms provide a reasonable explanation for maximum appeared in κ (T).
Study of ITO/Mo/CIGS/CdS/ZnO/Al Heterojunction Thin Solar Cell by Theoretical Simulations
Authors: Jakhmola Priyanka R. , Gupta Sanjay D. , Jha Prafulla K. , Bhatnagar Satya Prakash
Published: October 2014

Now a day, copper indium gallium diselenide (CIGS) have earned special interest among thin film solar cells. The bandgap of CIGS can be varied by varying gallium composition to obtain required bandgap that meets the solar spectrum to absorb most of the photons. In present work, ITO/Mo/CIGS/CdS/ZnO/Al heterojunction thin film cell has been designed by computer simulation using AFROS-HET. The cell parameters like open circuit voltage (Voc), short circuit current (Isc), efficiency (η) and fillfactor is also evaluated under AM 1.5 radiation by keeping device temperature at 400K. The Electrical, Photoelectroluminescence characteristics and Quantum efficiency of the cell are also simulated.
Investigation of Structural, Electrical and Magnetic Properties of Mixed Ferrite System
Authors: Astik Nidhi M. , Baldha G.J.
Published: October 2014

The mineral having chemical compositional formula MgAl2O4 is called “spinel”. The ferrites crystallize in spinel structure are known as spinel-ferrites or ferro-spinels. The spinel structure has an fcc cage of oxygen ions and the metallic cations are distributed among tetrahedral (A) and octahedral (B) interstitial voids (sites). A compound of Co0.85Ca0.15-yMgyFe2O4 (y=0.05, 0.10, 0.15) is synthesized in polycrystalline form, using the stoichiometric mixture of oxides with conventional standard ceramic technique and characterized by X-ray diffraction (XRD).The XRD analysis confirmed the presence of cubic structure. The intensity of each Bragg plane is sensitive to the distribution of cations in the interstitial voids of the spinel lattice. The computer program Powder X software for XRD analysis has been utilized for this purpose. The compositions of Co0.85Ca0.15-yMgyFe2O4 (y=0.05, 0.10, 0.15) ferrites have been prepared by standard ceramic method with double sintering at 950°C, 1100°C. In present study, we report the structural, electrical and magnetic properties of above said compound.
Theoretical Calculations on Molar Heat Capacities of MgRE Intermetallics Using First-Principles Calculations
Authors: Khan Afroj A. , Srivastava Vipul , Rajagopalan M. , Sanyal Sankar P.
Published: October 2014

Ab initio calculation on B2-Magnesium rare earth (RE), MgRE (RE=Sc, Y and La) intermetallics have been performed at T=0K with respect to their structural, electronic and thermal properties. The structural and electronic properties are derived using self-consistent tight binding linear muffin tin orbital method at ambient and at high pressure. Other properties like density of states, bulk modulus, electronic and lattice heat capacities for MgRE are calculated and discussed.
Transport Properties of Hexagonal YMn0.9Ru0.1O3 Compound
Authors: Thakur Rajesh K. , Thakur Rasna , Kaurav N. , Modi Anchit , Okram G.S. , Gaur N.K.
Published: October 2014

We report that the polycrystalline hexagonal YMn0.9Ru0.1O3 compound can be synthesized by using conventional solid state reaction method at a sintering temperature of 128000. The reflections/diffraction peaks observed in the XRD measurements matched exactly with standard (JCPDS) data for the hexagonal crystal structure of YMnO3 without any extra peaks due to impurities. The dc electrical measurements of the as prepared YMn0.9Ru0.1O3 compound have been carried out below room temperature down to the minimum possible. The electrical measurement of the Ru doped YMnO3 compounds reveal that the resistivity is suppressed with the addition of the ruthenium content and a consistent increase in the resistivity have been witnessed with decreasing temperature. In generalized sense the observed resistivity versus temperature behavior in the studied compounds suggests the induction semiconductor-like character in the material.KeywordsXRD, Electrical resistivity, Manganites