bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite-Element Modelling of the Impact Behaviour of Aluminium Nacre-Like Composite
Authors: Flores-Johnson E.A. , Shen Lu Ming , Guiamatsia Irene , Nguyen Giang D.
Published: June 2014

The demand for energy-absorbing lightweight structures for impact applications in automotive, aerospace and defence industry is rapidly growing, posing a challenge for innovative engineering design to maintain lightweight without reducing damage tolerance and impact and shock absorption. In this context, biological materials offer a source of inspiration for the design of new materials. Nacre, commonly known as the mother-of-pearl, is a biological material that exhibits outstanding mechanical properties due to its hierarchical structure, which includes a brick-like pattern, layer waviness and interface. Although nacre is made of 95% of aragonite, a brittle material, its toughness is about 3000 larger than that of aragonite. Research addressing the behaviour of nacre-like engineering composites is limited and this work intends to contribute to the understanding of such materials under impact loading.
In this paper, the study of the impact behaviour of layered nacre-like plates made of 1-mm thick tablets of aluminium alloy 7075 glued with toughened epoxy resin is performed using Abaqus/Explicit. A 9-mm steel spherical projectile with initial impact velocities in the range of 400-900 m/s is used. The epoxy material is modelled using a user-defined cohesive element that accounts for the experimentally observable increase in both strength and toughness in compression. Target thicknesses of 5 and 7 mm are modelled. The ballistic performance of bulk plates made of bulk Al-7075 is compared with that of nacre-like composite plates of the same thickness.
It is found that the nacre-like structures performed slightly better than the bulk plate for high impact velocities with a reduction of about 9% in the residual velocity; however, for lower impact velocities close to the ballistic limit, nacre-like plates performed worse than the bulk plate. The higher performance at higher impact velocities of the nacre-like composites is attributed to the hierarchical structure that enables both localized energy absorption by deformation of the metallic tablet and tablet interlocking due to the waviness and inter-layered delamination, which allows plastic deformation further away from the impact zone. It is concluded that nacre-like aluminium composite plates should be further investigated for their potential in designing protective structures because they could enable substantial improvements in weight-savings and in the ballistic performance of the structure. However, a quantitative assessment of their benefit warrants further numerical and experimental research.
Design Methods for Window Stopper Component Strength Cushions Operating under Wind Gusts
Authors: Nishie Gaku , Mori Takao
Published: June 2014

An evaluation of the impact forces imparted due to wind flow onto and across walls is necessary to improve the safety of stopper components in swing-type windows. A strong wind test was performed to measure the impact force imparted by wind, and the characteristics of the wind energy and resulting impact force were clarified. An impact force evaluation method based on a simple mechanical model was proposed. Furthermore, it was confirmed that the deformation of a plastic stopper component due to an impact force could be modeled via an empirical linear formula, derived experimentally using the impact force imparted in a drop weight load test. The proposed evaluation method is considered to be useful for the safety design of swing-type windows.
FEM Analysis of Cylindrical Structural Elements under Local Shock Loading
Authors: Kruszka Leopold , Vorobiov Yu.S. , Ovcharova N.Yu.
Published: June 2014

High rate deformations of structures cylindrical elements are considered 3D formulation. Elastic-plastic finite deformations and dynamic properties of material take into account. The problem become geometrically and physically nonlinear and finite element method is used. The numerical analyses of dynamics stress-strain state of real structures elements is executed.
Filtering Effects of Periodic Structure in Water Hammer
Authors: Nagai Minoru , Inaba Kazuaki , Takahashi Kosuke , Kishimoto Kikuo
Published: June 2014

In this study, we conducted water hammer experiments in the tube which was periodically supported by various numbers of clamps, named periodic structure, initiated by a projectile impact. The parts of the polycarbonate (PC) tube supported by 1-7 steel clamps make the tube stiffer and heavier than the original PC tube and are expected to cause a filtering effect of the frontal frequency components in the water hammer. According to our experimental observations, we confirmed that higher frequency components more than 1 kHz in the wave front were attenuated and the peak strains in circumferential direction of the tube were decreased 20% from the original PC tube. Moreover, we conducted numerical simulations of the water hammer wave similar to the experimental setup. Numerical results also revealed that frontal peak is attenuated 22% through periodic structure.
A FEM Study on Adiabatic Shear Band Formation in Tube Compression Driven by Electro-Magnetic Loading
Authors: Dong Xin Long , Li Lai Ze , Fu Ying Qian , Zhou Feng Hua
Published: June 2014

The adiabatic shear bands (ASB) of the thick-walled cylinder have been studied by many researchers in the recent years. The onset and evolutions of the multiple shear failure of metal cylinder under explosive loadings are affected by many factors such as the characteristics of the impulsive loadings, the dynamic behavior of the materials, etc. In this work, a tube compression driven by electro-magnetic forces is introduced, which enables to carry out the experiments of the spontaneous evolution of multiple adiabatic shear bands in metal tube. The FEM simulation was conducted to investigate the evolution process of strain localization with coupled thermo-mechanical analysis. The FEM results show that ASB initiates when the stress drops rapidly and strain growth and not when it reaches the maximum shear stress. Once the shear band is formed, elastic unloading occurs beside the shear band. The different behaviors of the damage introduced in the strain softening model affect the initial nucleation strain and the distribution of ASBs. With the increase of material damage softening, the initial strain of shear band decreases and the number of shear bands increases.
Hugoniot-Measurement Experiments of the Heated Samples
Authors: Oka Keiichi , Ogata Kenichi , Mashimo Tsutomo
Published: June 2014

Pressure calibration in static compression experiments have been undertaken on the basis of the equation of state (EOS) derived from the Hugoniot data of the pressure scale materials such as Au, Pt and MgO. However, room-temperature isothermal compression curve and further high temperature compression curve have been derived by using the assumed Grüneisen parameters, which cause the larger error at the higher temperature. If the Hugoniot data of the heated sample are measured, the accurate high-temperature EOS can be obtained, and the Grüneisen parameter (γ) can be directly discussed. We have measured Hugoniot data of Cu, W, Au, etc. by using the high-time resolution streak camera system equipped with a powder gun and two-stage light gas gun. In this study, the Hugoniot-measurement technique of the elevated temperature sample using high-frequency heating apparatus was established equipped with a powder gun. We succeeded in the measurement of the Hugoniot data (shock-velocity and particle-velocity) of the heated sample at 800°C on W.
Development of an Output-Bar Supporting Stand to Suppress Transverse Vibration in Dynamic Tensile Test of Sheet Steel
Authors: Itabashi Masaaki
Published: June 2014

In the one bar method, one of the standardized high velocity tensile testing techniques for thin steel plate, sometimes it shows an apparent effect of transverse vibration of an output bar on dynamic behavior of the plate. Suppressing the lateral vibration of the loading end of the bar is the most important factor to decrease the apparent effect, as pointed by Yoshida, Kuriyama, Uenishi and Takahashi in 2002, and the present author in 2011. He proposed an output-bar supporting technique with a polytetrafluoroethylene (PTFE) collar. In the former work, the lateral vibration was not fully suppressed, because the collar had some clearance to the output bar. He convinced that, in order to eliminate the clearance, it was worthy to give some transverse pre-load on the bar from the outer surface of the collar. However, the output bar is a load-sensing elastic body with strain gages adhered on it. The axial strain signal is a source of load detection. If such transverse compression is applied to the output bar, the axial skin strain of it is reduced to some extent. The key factor is the collar material, PTFE. This solid polymer possesses the lowest coefficient of friction in the situation of PTFE on steel, typically 0.05-0.10. The present author has modified an output-bar supporting stand to apply the lateral compressive load to the output bar with the divided PTFE collars which allow the smooth axial movement of the bar. The transverse compressive load is varied as 0, 70, 200 and 420 N. Obtained dynamic stress-strain curves at the strain rate of 500 s-1are compared each other to indicate the effect of the lateral compression on the bar. As a result, the lateral compression of 200 N is found as the most suitable condition.
The Development of Micro Ball Supersonic Impact Test System
Authors: Chung Dong Teak , Lee Joo Yeon , Kim Tae Yeon , Jin Doo Han , Kang Hyung
Published: June 2014

A micro ball supersonic impact test system was developed for the study of dynamic fracture of ceramic materials. This system consists of (1) low pressure gas gun, (2) sabot assembly and stopper block for velocity multiplication system, (3) velocity measurement device for sabot and ball, and (4) enclosed target box for final impact test. The principle of velocity multiplication system is similar to two stage gun. The plastic sabot assembly houses steel plunger and the void filled with silicone rubber. The sabot is stopped by the stopper block then the steel plunger inside the sabot compress the silicon rubber to high pressure to rupture the plastic membrane. Then the compressive energy of the silicon rubber is transferred to the ball. More than ten times of initial speed was attained. Non-contact velocity measurement system uses two set of ribbon laser with optical array sensor to measure the supersonic speed of the micro ball. Maximum speed up to 1200m/s for plastic and 600m/s for steel ball was attained. Perforation test of plastic film laminated glass window was successfully done by the developed impact system.
Investigation of High-Speed Loading Effects on the Properties of Ferromagnetic Alloys Processed in an External Magnetic Field
Authors: Sudenkov Yuri V. , Atroshenko Svetlana , Smirnov Ivan , Naumova Natalya , Sun Xue Yin
Published: June 2014

The behavior of the ferromagnetic alloy based on Fe-Cr-Co under high-speed loading is presented. Three types of samples were prepared with different pre-treatments: quenching only; quenching and ageing; and quenching and ageing under an intense external magnetic field. The sub-microsecond impact load was created by the installation for the electrical explosion of foils. The developed method of loading allows a pressure pulse to be registered before impact on a flat sample and after its exit to a free surface of this sample. Changes in the mechanical properties of the ferromagnetic alloy with various technologies of preliminary processing before and after shock loading are discussed.
Evaluation of Sliding Behavior of Simple Structures for Oblique Collision
Authors: Watanabe Takeru , Nishimura Naoya , Watanabe Hiroka , Nakadate Syouta , Murase Katsuhiko
Published: June 2014

When a simple structure collides with inclined barrier, behavior and deformation of the structure after impact are different in the case in which the structure slides on a contact surface or the case in which it does not slide. In order to investigate the structural collapse behavior for oblique collided structure, therefore, it is important to clarify the sliding behavior of the structure on the contact surface. The sliding behavior of the structure during collision was estimated according to theoretically obtained the equation considering the equilibrium of change in the momentum and the impulse before and after the collision. For evaluating the sliding behavior of the simple structure, the impact test by the drop type impact testing machine was carried out to collide with inclined barrier. In the impact test, the circular plate of 60 mm diameter and 10 mm thickness was used as the simple structure, and impacted with various collision velocities (range from 2 to 6 m/s). The sliding behavior of the simple structure at the collided surface was observed by high speed camera, and evaluated by the image analysis. The theoretical result was compared to evaluate with experimental results.
Characteristic Evaluation of the Enforcement Device for the Car
Authors: Nakadate Syouta , Nishimura Naoya , Watanabe Takeru , Watanabe Hiroka , Murase Katsuhiko
Published: June 2014

In this study, collision and braking behavior and braking distance of the enforcement device were investigated for characteristic evaluation. The basic theory for the braking distance was derived using the law of the energy conservation. In this basic theory, the braking distance was compared with difference collision speed and arm angles of enforcement device. And also, the collision experiment was carried out by simple model of the enforcement device and the car. The behavior of the enforcement device was examined by the simple model with 3 kinds of different arm angles. The braking distance by the experiment was well agreement with theoretical result. It is possible to optimize and improve the enforcement device by these evaluations of collision behavior.
Effect of High Loading Rate on SCC Behaviour of SUS304 Austenitic Stainless Steel
Authors: Kumegai Akihiro , Tanabe Yuji , Suzawa Hiroaki
Published: June 2014

This study deals with the effect of intermittent impact loading on the SCC growth behaviour of SUS304 austenitic stainless steel. To this end, the Split-Hopkinson pressure bar (SHPB) experiments on SUS304 were performed first to establish the dynamic tensile stress-strain response at strain rates up to 700s-1. The analyses of dynamic stress intensity factors for wedge loading experiments on modified compact tension specimens, designated WLCT, were then performed by the finite element method. The SCC experiments with the intermittent impact loading for WLCT specimens of SUS304 by the use of the SHPB were mentioned and discussed as well.
Strengthening of FCC Metals at High Strain Rates
Authors: Couque Hervé
Published: June 2014

The influence of strain rate over domains involving the thermal activation and the viscous drag behavior of the dislocations has been investigated for a series of face centered cubic metals. The effect of grain size on the strain rate threshold delimitating the two domains in compression was examined with grains sizes ranging from 0.1 to 100 μm for nickel and copper. The tensile strengthening occurring at high strain rates for an austenitic stainless steel was also investigated.
Modelling of Formation of Adiabatic Shear Bands
Authors: Bassim Nabil , Delorme Jeffrey
Published: June 2014

Adiabatic shear bands are microstructural features that appear when metals, and some non-metals are subjected to impact loading at strain rates in excess of 103 s-1 and large strains. The formation of these bands is generally attributed to several competing mechanisms, among them is an initial strain hardening followed by adiabatic thermal softening that may lead to crack initiation within the bands. The authors have developed a model for formation of adiabatic shear bands in metallic materials as they are formed during testing using a torsional Hopkinson Bar. The model relies on a one dimensional analysis which predicts accurately the two steps of forming adiabatic shear bands in terms of strain hardening followed by thermal softening. In this current research, the model is extended to a two-dimensional analysis which would be suitable for application in either a two bar compression Split Hopkinson Bar or in a direct impact compression system developed by the author (Nabil Bassim) to produce high strain rates and large strains. The algorithm relies on applying the concept of dynamic recrystallization in order to determine the onset or initiation of the adiabatic shear bands.
Incorporation of Pd Nanoparticles on Rod and Necklace-Like SBA-15 Supports Materials
Authors: Lee Siew Pei , Ramli Anita , Kutty Muralithran G. , Hamid Sharifah Bee A.
Published: June 2014

Ion-exchange of palladium (Pd) precursor for two different types of well-ordered SBA-15 morphologies, necklace-like and rod-like, was studied. Approximately 3.8 wt% Pd was successfully incorporated into SBA-15 at pH 10.3. Formation of SBA-15 and Pd/SBA-15 were characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Thermogravimetry with Simultaneous Difference Thermal Spectroscopy coupled with mass spectrometer (TG/SDTA-MS), Thermogravimetry in combination with Simultaneous Difference Thermal Spectroscopy (TG-SDTA), Inductive Coupled Plasma Mass Spectrometer (ICP-MS) and N2 adsorption-desorption. Reduction of surface area and pore volume of support for Pd/SBA-15 samples may indicate the encapsulation of PdO particles within mesoporous channels of SBA-15.
Effect of Nanonization on Physicochemical Properties of Centella asiatica Powders
Authors: Borhan M.Z. , Ahmad R. , Rusop Mohamad , Abdullah Saifollah
Published: June 2014

Centella asiatica (C. Asiatica) contains asiatic acid as one of bioactive constituent that has the commercial medicinal value such as anticancer and also possess wound healing property. The ball milling process was carried out at 0.5, 4 and 8 hours. The effects of ball milling at different times were characterized using particles size analysis (Photon Correlation Spectroscopy) and Fourier Transform infra red (FTIR) Spectroscopy. The surface morphology was characterized by Field-Emission Scanning Electron Microscope (FESEM). As a result, smallest particles size by mean 279.5 nm was produced at a longest milling time (8 hr) and FTIR spectra shows there is no obvious change in the structure of C. asiatica nanopowders as compared to the micropowders. Centella asiatica nanopowders shows good extraction yield of asiatic acid with 5.5 μg/ml of yield but poor inhibition of DPPH as compared to micropowders.
Carbon Dioxide Retention on Bentonite Clay Adsorbents Modified by Mono-, Di- and Triethanolamine Compounds
Authors: Elkhalifah Ali E.I. , Bustam Mohammad Azmi , Azmi Mohd Shariff , Murugesan T.
Published: June 2014

A series of organic-inorganic hybrids were developed via intercalation process of primary, secondary and tertiary ammonium cations into different alkali and alkaline earth and transition metal cation forms of bentonite clay to be used as adsorbent materials for CO2capture under ambient temperature and slightly high pressure. The effect of the molar mass of amines on the structural characteristics, surface properties and CO2loading capacity of bentonite clay were investigated by X-ray diffraction, Brunauer-Emmett-Teller method and Magnetic Suspension Balance equipment, respectively. X-ray diffraction results revealed that the basal spacing of bentonite clay after modification with amines was increased with the molar mass of amine used, while BET results showed an inverse effect of the molar mass of amines on the surface area of the synthesized materials. The CO2loading capacity of the examined samples revealed that bentonite clay modified with monoethanolammonium cations retained higher CO2amount compared to those modified with di-and triethanolammonium cations. CO2adsorption isotherms on MEA+-Mg-MMT were conducted at 298, 323 and 348 K and different pressures. A decrease in CO2uptake with increasing temperature was observed, suggesting the exothermic nature of the adsorption process.
Leachability of Solidified Petroleum Sludge
Authors: Mohd Zain Asna , Md Ghazaly Shaaban , Hilmi Mahmud
Published: June 2014

Petroleum sludge was solidified in ordinary Portland cement, and the leachability test was performed based on American Nuclear Society 16.1 to produce leachate. The organic in solidified sludge was extracted by micro solid extraction to determine the organic in the sample. Organic in the leachate sample was detected by solid phase micro extraction by head space polydimethyl siloxane fiber using gas chromatography mass spectrometry. The targeted organic compounds in solid sample and leachate were quantified by the benzene, toluene, ethyl benzene, xylene, naphthalene and phenanthrene standards. The organic compounds in solidified sludge consist of aliphatic and ester acid with long carbon chain of Carbon 15 to Carbon 64. The aliphatic group in the leachate was found at the reduced rate of about tenfold of the solid sample. Derivative leachate products mainly composed of cyclic siloxane compounds. The metals leachability in the acidic medium depends on the metal hydroxide solubility value. High lead mobility in the acidic medium was due to its high solubility induced the highest effective diffusion coefficient of 1.59 x 10-07cm2/s.
Physical Absorption of CO2 Capture: A Review
Authors: Ban Zhen Hong , Keong Lau Kok , Mohd Shariff Azmi
Published: June 2014

Removal of CO2 had been one of the main issues facing in worldwide. Intensive researches are still going on to effectively reduce CO2 at low cost. Physical absorption is one of the well-established technologies used to removal CO2 from other gases. The physical absorption process is simple; whereby it contains only one gas liquid contactor and a series of flash tank to regenerate solvent. The CO2 will be absorbed in the physical solvent in the high pressure gas liquid contactor and flashed out in the medium and low pressure flash tank. The advantage of using physical solvent is that the CO2 is absorbed without any chemical reaction involved, thus it can be flashed out easily by reducing the pressure, passing inert gas through the solvent and mild thermal regeneration. The physical absorption is the best operated at high pressure and low temperature as the solubility of CO2 in the solvent is high at the particular condition. Researches carried out currently are focusing on solvent development, absorption and desorption process development and mathematical modeling.
Modeling the Effect of Temperature-Induced Surface Tension Gradient in Coating Processes
Authors: Abdullah Bawadi , Vo Dai Viet N. , Chowdhury Sujan
Published: June 2014

The coating of the fluorescent-lamp material inside the fluorescent tube is prone to defect such as dark line formation. A one-dimensional mathematical model based on Navier-Stokes equation, which describes the flow of drying coating on horizontal planar substrates, was developed to investigate the defect formation. The effect of temperature distribution on surface tension gradient was incorporated into the model, to quantify defect formation in drying coating. The results showed that, temperature-induced surface tension gradient plays a major role in defect formation while the effect of pressure gradient is insignificant. The evaporation rate and viscosity affect the defect thickness and spread, and also the defect formation time. The temperature gradient seems to have the largest influence on surface tension gradient, thus defect formation. The model developed can be used as a process analysis tool in industrial applications of fluorescent tube coating.
Effect of Bulk Temperature and Heating Regime on Crude Oil Fouling: An Analysis
Authors: Ramasamy M. , Deshannavar Umesh B.
Published: June 2014

Semi-empirical threshold fouling models predict higher fouling rates at high surface or film temperatures. Several experimental fouling data reported in literature and from our study were analyzed with respect to increase in surface and bulk temperatures that showed a decrease in fouling rates. The existing threshold fouling models do not adequately describe the phenomenon of decreasing fouling rates with increase in surface or bulk temperatures. The possible causes including the effect of temperature difference, heating regime and solubility of fouling precursors were analyzed and reported.
A Comparison of Co-Current and Counter-Current Modes of Operation in Urea Prilling Tower
Authors: Rahmanian Nejat , Homayoonfard Marjan
Published: June 2014

In this paper, a model for urea prilling tower with co-current flow of cooling air and urea prills (particles) is presented. The process is modelled by simultaneous solution of the differential equations for hydrodynamics, heat and mass transfer between the air and prills. The process variables such as temperature, absolute and relative humidity of air along the height of the tower were obtained from this model. Temperature and moisture distribution of urea prills and their radial and vertical velocities were also calculated. The results of the present model were compared with the counter-current operation model available in the literature. The simulation results show that heat transfer performance for co-current operation is significantly less than that of the counter-current scenario. This is more pronounced for small prills, i.e. 1.0 mm than that of the large prills. The advantage of the model is that it can be used to investigate influence of operating parameters on efficiency of the co-current process. This also helps us to set the process control strategies for design and quality control purposes of the process.
Detection and Correction of Gain Mismatches of Wood-Berry Column Using Linear Residual-Input Ratio
Authors: Kamal-Iqbal Nur Hidayah , Yusoff Nooryusmiza , Bahakim Sami Saeed
Published: June 2014

Mismatches between model and plant can degrade the controller performance. Detection and correction of model parameters are required to prevent re-identification process of the whole plant. This paper proposes a method to automatically detect and correct model gain mismatch in the case of Wood-Berry column. Taguchi experiments are initially carried out to identify the most significant model gains. A set of variables called the linear residual-input ratio (LRIR) are developed to detect changes in the plant gains thus correcting the gains to bring the process to the desired setpoint. The proposed method is able to correct the mismatches in magnitude for individual and multiple gains within the range of the linear equations.
Resilience Analysis of a Pipe Segment System Carrying Superheated Steam
Authors: Guha Sirshendu , Das Sudip Kumar
Published: June 2014

A pipe segment system has been used to estimate its inherent resilience properties for the variation of mass flow rate, inlet temperature and inlet pressure. Superheated steam is taken as the process fluid. The magnitude of the resilience decreases from 927.8 kJ/m3s to 43 kJ/m3s and 31.5 kJ/m3s for variation of mass flow rate, inlet pressure and inlet temperature respectively. In this work, a novel methodology has been described for quantification of inherent system resilience and resilience magnitude has been found to be highest (927.8 kJ/m3s) in case of variation of mass flow rate through the pipe segment system. A useful correlation T = Ta(1-e-nL)+Tse-nL has been formulated for estimation of process fluid temperature, T at any pipe length, L.
Modeling of Gas Holdup and Pressure Drop Using ANN for Gas-Non-Newtonian Liquid Flow in Vertical Pipe
Authors: Bar Nirjhar , Das Sudip Kumar
Published: June 2014

This paper is an attempt to compare the the performance of the three different Multilayer Perceptron training algorithms namely Backpropagation, Scaled Conjugate Gradient and Levenberg-Marquardt for the prediction of the gas hold up and frictional pressure drop across the vertical pipe for gas non-Newtonian liquid flow from our earlier experimental data. The Multilayer Perceptron consists of a single hidden layer. Four different transfer functions were used in the hidden layer. All three algorithms were useful to predict the gas holdup and frictional pressure drop across the vertical pipe. Statistical analysis using Chi-square test (χ2) confirms that the Backpropagation training algorithm gives the best predictability for both cases.
Simulation of Hydrodynamics and Reaction Behavior in an Industrial RFCC Riser
Authors: Ahmed Aisha , Maulud A. , Ramasamy M. , Keong Lau Kok , Shuhaimi Mahadzir
Published: June 2014

A 2D axi-symmetric, steady state and pressure-based model for the riser of an industrial RFCC unit was developed with ANSYS FLUENT in workbench 13.0. The EulerianEulerian approach was applied to simulate the flow behavior of the two phases and the catalytic cracking reactions. Thek-εgassolid turbulent flow per phase model was used, and the particle-level fluctuations are modeled in the framework of the kinetic theory of granular flow. Two different drag models were used separately to simulate the gas solid interaction in the riser fluidized bed. The 14-lump kinetic model was chosen to describe the complex catalytic cracking of the heavy residual feed stock. The particle volume fraction, velocity and temperature profiles, as well as product yields in the riser were analyzed and validated with results from open literature and the industrial RFCC plant data.
Performance Study of Ni Catalyst with Quicklime (CaO) as CO2 Adsorbent in Palm Kernel Shell Steam Gasification for Hydrogen Production
Authors: Khan Zakir , Yusup Suzana , Ahmad Murni Melati
Published: June 2014

There is a need to search for efficient material that reduce CO2 content and enhance the hydrogen composition in the product gas from biomass steam gasification particularly for large scale production. The present study was carried out to perform the characterization of commercial quicklime as CO2 absorbent and Ni powder as catalyst. The chemical composition of the materials perform using x-ray fluorescence (XRF) indicated high amount of CaO and Ni in the bulk samples. Using XRF and SEM analyses, it was found that both materials showed high crystalinity. The adsorption isotherm from physisorption analysis suggested that the materials exhibits Type II category according to the IUPAC classification scheme. These types of material exhibit mesoporous structure which was also verified by the pore size of the samples found via BET analysis. The BET surface area reported was 4.16 m2/g and 0.78 m2/g for quicklime and Ni powder, respectively. In conclusion, commercial quicklime has the potential as CO2 absorbent, based on the pore size and surface area. Conversely, the surface properties of the Ni powder were found relatively lower as compared to other commercial catalysts available for biomass steam gasification.
Gas Permeation Models in Mixed Matrix Membranes for Gas Separation
Authors: Rafiq Sikander , Maulud Adulhalim Shah , Man Zakaria , Muhammad Nawshad
Published: June 2014

Various theoretical models on CO2 permeation were discussed that included Maxwell model, Bruggeman model, Lewis-Nielson model and Pal model. These models were used for comparing the relative permeance of CO2 with the previously published experimental data on silica nanoparticles filled polysulfone/polyimide (PSF/PI) mixed matrix membranes (MMMs). The results showed that the deviation was in the increasing order: Lewis-Nielsen model< Maxwell model< Pal model< Bruggeman model. All these models assumed that the fillers are spherical in shape. A scanning electron microscope (SEM) cross-sectional image indicated that the silica particles were prolate ellipsoids that were dispersed in the matrix. To investigate the prolate effect, the Maxwell-Wagner-Sillar (MWS) model was employed. The evaluation from cross-sectional image of the membrane structure indicated that the shape factor along z-direction gave a minimum deviation of 17.52%-20.10% at 2-10 bar feed pressure respectively.
Modification of Adsorbents for High CO2 Content Capture from Stranded Natural Gas Reserve: A Critical Review
Authors: Mohd Noor Nadia Isabella , Eldemerdash Usama , Azmi Mohd Shariff
Published: June 2014

.Carbon dioxide (CO2) commonly exists as undesirable component in natural gas streams. The continuous growing of the global demand makes it necessary to overcome the high CO2content obstacle of stranded reserves. A wide variety of acid gas removal technologies have been developed, including chemical and physical absorption processes but none of them can combine the high efficiency and economic energy consumption. Each process has its own advantages and disadvantages. Using of adsorbents increasingly being selected for newer projects, especially for applications that have large flow, high CO2content and located in remote locations such as offshore where compact and highly effective technology is required. This review highlights the importance of adsorbent modification on CO2removal from natural gas reserve at high pressure and temperature using physical adsorbents such as zeolite and molecular sieve. Then, the focus is turned on the adsorbents chemical modification using organic amines to improve the adsorption efficiency towards CO2.
Optimized TiO2 Nanocrystallites Aggregates for Enhanced Efficiency in Dye Solar Cells
Authors: Zaine Siti Nur Azella , Mohamed Norani Muti , Bustam Mohamad Azmi
Published: June 2014

TiO2 aggregates-based dye solar cells (DSCs) have gained an increasing attention due to their enhanced harvesting of light radiance. The capability of this photoelectrode material is attributed to the submicron spherical aggregates that introduce light scattering effect which can generate more electrons whilst high internal surface area for dye chemisorption is provided by nanocrystallites which made up the aggregates. Here, TiO2 aggregates (0.45-0.20 μm) composing of nanocrystallites (10-28 nm) with desired physicochemical properties for enhanced overall light conversion efficiency of DSC were synthesized by varying the water content in the hydrolysis of titanium alkoxide in ethanol and calcination temperature. TiO2 aggregates obtained were characterized using FESEM, XRD and UV-Vis spectroscopy. The assembled DSCs were then evaluated using solar simulator under AM 1.5 (100 mW/cm2) simulated sunlight. With higher water content in the hydrolysis process, the aggregates reduce in size and lose their spherical shapes resulting in lower absorption intensity indicating the occurrence of low light scattering in the TiO2 film. Nanocrystallites were found to have an increasing size of 12 nm to 28 nm with increasing calcination temperature of 400°C to 700°C. Sample of aggregates calcined at 450°C recorded the highest efficiency (~4%). Highest conversion efficiency was observed for DSC that used well-defined spherical TiO2 aggregates composing of nanocrystallites which were synthesized at optimum synthesis parameter which is by using ethanol with low water content (0.9 vol%) followed by calcination at 450°C. Thus, optimized TiO2 nanocrystallites which form spherical aggregate is critical in order to improve light harvesting efficiency of DSCs.
Ethanol Production from Hydrothermal Pretreated Empty Fruit Bunches
Authors: Siti Aisyah Mohd Saman , Petchpradab Pacharakamol , Uemura Yoshimitsu , Yusup Suzana , Kanna Machi , Matsumura Yoshimitsu
Published: June 2014

Separate hydrolysis and fermentation (SHF) is the common process in producing ethanol from lignocellulosic biomass. Nowadays, simultaneous saccharification and fermentation (SSF) process has been seen as potential process for producing ethanol with shortens process time with higher yield of ethanol. Hence, in the current work, the utilization of empty fruit bunches (EFB) in SSF process was studied. In order to improve saccharification reactivity of EFB, hydrothermal pretreatment at 180 and 220 °C was used to pretreat EFB. The findings showed that SSF has the potential in producing ethanol from EFB.
The Influence of High Plastic Strain on Precipitation from Solid Solution in Third Generation Al-Li Alloys
Authors: Cassada William A. , Shiflet Gary J.
Published: June 2014

Different levels of compression plane strain were applied to third generation aluminum alloys to simulate rolling-type deformation following solution heat treatment. The aluminum alloys utilized were extruded production samples provided by Alcoa in a solution heat treated condition (T4). The alloys included in this study are AA2099-T4 containing 1.78 wt% lithium, and AA2055-T4 containing 1.13 wt% lithium and an additional component of 0.45 wt% silver. Following plane strain compression, the samples were isothermally heat treated at 155 °C for times up to about 7 days. Data presented include hardening behavior values and various electron microscopy techniques using conventional TEM to document subsequent precipitate sequence distributions and general kinetics.
Effects of Pre-Aging and Natural Aging on Bake Hardening Behavior in Al-Mg-Si Alloys
Authors: Takaki Yasuo , Aruga Yasuhiro , Kozuka Masaya , Sato Tatsuo
Published: June 2014

The effects of pre-aging and natural aging on the bake hardening behavior of Al-0.62Mg-0.93Si (mass%) alloy with multi-step aging process were investigated by means of Vickers hardness test, tensile test, differential scanning calorimetry analysis (DSC) and transmission electron microscopy (TEM). The characteristics of nanoclusters (nano scale solute atom clusters) formed during pre-aging and natural aging were also investigated using the three dimensional atom probe (3DAP) analysis. The results revealed the occurrence of natural age hardening and that the bake hardening response was decreased after the extended natural aging even though the pre-aging was conducted before natural aging. Since the 3DAP results exhibited the Si-rich clusters were newly formed during extended natural aging, it was assumed that the Si-rich clusters caused the natural age hardening and the reduced bake hardening response corresponding to Cluster(1). The decrease of the bake hardening response was markedly higher in the later stage of bake hardening than in the early stage. The size of the β’’ precipitates were reduced with increasing the natural aging time. Exothermic peaks of Peak 2 and Peak 2’ were observed in the DSC curves for the alloys pre-aged at 363K. Peak 2’ became larger with the natural aging time. This is well understood by the following model. The transition from Cluster(2) to the β’’ phase occurs preferentially at the early stage of the bake hardening. Then the growth of the β’’ phase is inhibited by the presence of Cluster(1) at the later stage of bake hardening. The combined formation of Cluster(1) and Cluster(2) by the multi-step aging essentially affects the bake hardening response and the β’’ precipitates in the Al-Mg-Si alloys.
Microstructures and Mechanical Properties of an Artificially-Aged Al-Mg-Ga Alloy
Authors: Park Myeong Heom , Terada Daisuke , Marya Manuel , Tsuji Nobuhiro
Published: June 2014

The microstructures of an Al-Mg-Ga cast alloy have been investigated to fundamentally understand its hardening response during heat-treatment. In as-cast, solution heat-treated, and aged conditions, the alloy is characterized by having a variety of metallurgical phases with unique morphologies and chemical compositions. Micro-hardness indentations subsequent to artificial aging between 50°C and 300°C revealed that the investigated Al-Mg-Ga alloy is capable of Vickers hardness values in excess of 180, therefore demonstrating a remarkably elevated age hardening behavior relative to conventional aluminum alloys. SEM and TEM observations, coupled with DSC analysis with several aging conditions, revealed that hardening is induced by submicron platelet precipitates having the length, width, and density that depend largely on the alloy aging conditions.
A New Ultrahigh Strength Al-Cu-Li Alloy
Authors: Zhong Ji Fa , Zheng Zi Qiao , Luo Xian Fu
Published: June 2014

In this work, a new ultra-high strength Al-Cu-Li alloy was investigated. The ultimate strength, yield strength and elongation of the newly designed alloy by artificial aging are 647.2MPa, 609.4MPa and 7.3% respectively. Among the main strengthening phases of T1, θ′ and S′ in the experimental alloys, T1 is the dominant one. The combined addition of Mg and Ag promoted the precipitation of T1 and increased the strength of the new alloy greatly. Zn had a similar effect as Ag during the aging strengthening progress, when added with Mg. Among the three micro-alloying elements, Mg, Ag and Zn, Mg had the strongest influence on age strengthening. Compared with the combined additions of (Mg +Ag) and (Mg + Zn), (Ag + Zn) had the weakest influence on aging strengthening. Pre-deformation before aging promoted the precipitation of T1 phase which weakened the influence of micro-alloying elements (Mg, Ag and Zn) on strengthening the alloys and minished the strength difference between alloy containing (Mg + Ag + Zn) and alloys containing two of them.
Influence of AlCuSc Ternary Phase on the Microstructure and Properties of 1469 Alloy
Authors: Jia Min , Zheng Zi Qiao , Luo Xian Fu
Published: June 2014

Microstructure evolution and mechanical properties of a 1469 alloy and a Sc-free1469 type alloy were examined. SEM observation indicates that AlCuSc ternary phases (W) are formed after homogenization annealing, and cannot be dissolved during the following heat treatments. These coarse particles consume abundant Cu atoms from the Al matrix that are available for solutioning, which results in the decrease of precipitation of the T1 phase during aging treatment. The W phase has negative effects on the examined alloy’s mechanical properties. The tensile strength of Sc-added alloy is 40MPa lower than that of the Sc-free alloy. The formation of the W phase has a close relationship with Cu/Sc ratio, which shows the importance of controlling the concentration of Cu and addition of Sc. Formation of W phase suppress the effect of precipitation hardening of the T1 phase in high strength Al-Cu-Li alloys
Study of Metal Quality and Melt Yield from Remelts of (i) Turnings AA3005 and (ii) Coil AA3003
Authors: Kristoffersen Lill June , Kvithyld Anne , Nordmark Arne , Johansson Anders U. , Sæter Jan Anders , Engh Thorvald Abel
Published: June 2014

It is important for aluminum producers to predict metal quality and melt yield when scrap is remelted. Therefore, these parameters are studied in individual remelt experiments with (i) Turnings AA3005 and (ii) Coil AA3003 as scrap, as a function of percent added scrap up to 33 %. To ensure same melting conditions the scrap is melted in crucibles inside a Morgan resistance furnace, measuring temperature and hydrogen. Bifilm index is used as a measure of metal quality. The results indicate that the addition of scrap (up to 33 %) does not alter metal quality. Melt yield is however affected, with a metal recovery of around 90 % for the different types of scrap.
Melt Conditioned Twin Roll Casting (MC-TRC) for Aluminium Alloys
Authors: Barekar Nilam S. , Das Sanjeev , Fan Zhong Yun
Published: June 2014

Twin roll casting (TRC) has been demonstrated to be an effective route for producing Al sheet at a reduced cost. However, the quality of the Al alloys sheets produced by the TRC process is limited by the formation of centreline segregation, which hampers the downstream processing, degrade the mechanical performance of the final rolled products, limit TRC to dilute alloys with a narrow freezing range, and hence prevent its application in a wide range of engineering sectors. To improve the quality of the TRC strips, a new technology, melt conditioning twin roll casting (MC-TRC) has been developed. It has been demonstrated that the MC-TRC process is capable of producing Al-alloy strips with minimal centerline segregation which is attributed to enhanced nucleation by well dispersed naturally occurring oxides in liquid Al alloys. This work aims to investigate the upper composition limit allowed for the MC-TRC process using the binary Al-Mg alloys as model alloys. The results showed that melt conditioning increases the range of alloys (solute content up to 7%) that can be twin roll cast without severe segregation.
Effect of Thermomechanical Processing on Electrical and Mechanical Properties of Aluminum Conductor Alloys
Authors: Pan Lei , Bourassa Bruno , Chen X.-G.
Published: June 2014

The effect of different thermomechanical processes (hot extrusion and Properzi continuous rolling) on the electrical and mechanical properties of the Al-Fe aluminum conductor alloys was investigated. The microstructural evolution of the supply rods was characterized by an optical microscope, a transmission electron microscope and the electron backscatter diffraction technique (EBSD). Tensile tests and electrical conductivity measurements were carried out at room temperature on the supply rods. Results showed that, at the same Fe content, the continuously rolled rods demonstrated higher tensile strength but lower elongation and electrical conductivity compared with those of the extruded rods. A partially recrystallized structure along with a big subgrain size appeared in the extruded rods while only a dynamic recovery with a small subgrain size was found in the continuously rolled rods. The precipitation of iron-rich dispersoids was observed in the extruded rods and is associated with a depletion of the iron concentration.
The Evolution of Microstructure and Texture during Thermomechanical Processing of Al-Mg-Si-Cu Alloy
Authors: Wang Xiao Feng , Guo Ming Xing , Cao Ling Yong , Cui Li , Zhang Ji Shan , Zhuang Lin Zhong
Published: June 2014

In order to improve formability, it is practicable to control the texture through adjusting process parameters. This work describes the evolution of microstructure and texture during thermomechanical processing of Al-Mg-Si-Cu alloy. With the change of deformation conditions, both the microstructure and texture change dramatically. After hot rolling from 90 mm to 7.5 mm, H and E texture components in the surface layer become dominant due to non-uniform deformation. And then with the increasing of cold rolling deformation from 7.5 mm to 4.0 mm, the texture components gradually change from shear texture to typical fcc texture, i.e. Copper, S and Brass textures, and their intensities also increase. And these texture components transform to some uncommon texture components after intermediate annealing, including {013}<001>, {001}<130>, Goss texture, {556}<110> and {111}<110> texture, not as the typical recrystallization texture components. Continually giving a cold rolling deformation from 4.0 mm to 1.0 mm, not only Copper, S, Brass textures, but also Goss texture due to the lower deformation can be found in the alloy sheet. The high temperature solid solution treatment can result in the complete recrystallization and the formation of recrystallization texture, Cube, Goss and R texture, which results in the high formability of experimental alloy.
Influence of Alloying Elements and Processing in AA 8006-Alloys on Microstructure and Properties of Rolled Products
Authors: Hasenclever Jochen
Published: June 2014

The effect of Manganese as alloying element and important process parameters on the microstructure of AA 8006-alloys was investigated in this work. Furthermore the effect of different casting processes (CC-casting versus DC-casting) was studied. The addition of higher Mn-contents results in higher strength values and a better thermal stability. The recovery and recrystallisation behaviour is also influenced by the processing. Important process steps are the preheating and the intermediate annealing. The properties at final thickness are also related to the applied casting process ( DC versus CC).