bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation of Mechanical Properties of AlSi20Cu2Ni1 Alloy with Co Addition and Ultrasonic Treatment
Authors: Sha Meng , Wu Shu Sen , An Ping , Mao You Wu
Published: May 2014

The combined effects of the Co addition and Ultrasonic Vibration (USV) on microstructure and properties of Al–20Si–2Cu–1Ni–0.6Mg alloy were studied in this paper. The volume fraction of Co-bearing intermetallic compounds was increased with the increasing of Co content when various levels of Co (from 0% to 1.5%) added respectively into the alloys whether they formed in traditional casting or with USV treatment. The Co-bearing compounds presented as Chinese script or granular when Co was equal or less than 0.7% and turned into dendritic or fish-bone shape when Co was more than 0.7%. USV treatment applied around liquidus temperature of the melt could lead to a refinement of Co-containing compounds by promoting nucleus formation, hindering preferential growth on certain direction, and enlarging solute diffusion coefficient. The addition of equal or less than 0.7% Co, as well as application of USV is very effective in promotion of tensile strength of the hypereutectic Al–Si alloys.
Determination of Substitutional-Interstitial Interaction from Chemical Potentials of Interstitials in the Steel Matrix
Authors: Shan Yao V. , Svoboda Jiří , Fischer Franz Dieter , Kozeschnik Ernst
Published: May 2014

The interaction between interstitially diffusing atoms and substitutional solute atoms, acting as trapping sites, causes a non-negligible influence on the diffusion process itself and, consequently, on many aspects of alloys, such as phase transformations, solubility, precipitation of carbides and nitrides etc. The most important quantity in this treatment is the so-called trapping enthalpy (depth of trap), which has been used in several approaches in literature over the last century. However, the determination of the trapping enthalpy so far relies on approximations or assumptions on the one hand (statistical approaches, quasi chemical approach) or is significantly limited due to high complexity (ab initio approaches) on the other hand. The model introduced in this paper illustrates a rigorous and efficient thermodynamically-based concept utilizing only the dependence of the chemical potential of the interstitial component on the chemical composition of the alloy. Such a dependency is available in a very precise form from CALPHAD thermodynamic databases. Using the most recent databases available, the trapping enthalpies of carbon and nitrogen at various solute atoms (trapping sites) are evaluated for austenitic and ferritic steels. Good agreement with previous literature results is observed. The flexibility of the concept allows also for the treatment of trapping in a multi-component system, where different types of solute atoms are responsible for different depths of traps.
Influence of Filler Rod Composition on the Strength of Tungsten Inert Gas Welded Magnesium Alloy Joint
Authors: Shimomura Shinya , Minomo Taiki , Takigawa Yorinobu , Uesugi Tokuteru , Ueda Mitsuji , Kinomoto Yutaka , Higashi Kenji
Published: May 2014

The influence of filler rod composition on the strength of Tungsten Inert Gas (TIG) welded magnesium alloy joint was investigated. Samples were rolled AZ31 (Mg-3Al-1Zn) magnesium alloy as base metal and drawn AZ31, AZ61 and AZ91 magnesium alloys as filler rod. The results show that all fracture points were fusion zone (FZ), and each joint efficiency (=joint strength/ base metal strength) was 70.7%, 80.0% and 73.1% when using AZ31, AZ61 and AZ91 filler rod. When using AZ91 filler rod, 0.2% proof stress was the highest but the elongation was the lowest among the three conditions, and joint efficiency was lower than that when using AZ61 filler rod. It is thought that welded joint was strengthened by solute strengthening, but excess addition of aluminum facilitated crystallization of Mg17Al12 phase. This is the reason why elongation and joint efficiency when using AZ91 filler rod decreased. In conclusion, it is effective to use filler rod which does not excess solid solubility limit.
Design and Fabrication of New Ti-Based Ternary Metallic Glasses Based on Effective Atomic Radius in the Ti Solid Solution Calculated by Ab Initio Calculation
Authors: Shirasawa Naoya , Ito Ren , Takigawa Yorinobu , Uesugi Tokuteru , Higashi Kenji
Published: May 2014

New Ti-based ternary metallic glasses were designed and fabricated. A new parameter called effective atomic radius in the Ti solid solution from ab-initio calculation was used to design of the Ti-based metallic glasses. From the effective atomic radius, Ti-Zr-Mn, Ti-Zr-Fe and Ti-Zr-Co systems can be considered as a new Ti-based ternary metallic glass. And the reported scheme based on the concept of binary eutectic clusters is applied to predict alloy composition which shows glass transition.We prepared the Ti42Zr22Mn36, Ti43Zr29Fe28 and Ti44Zr30Co26 alloy sheets by a single-roller method. It showed that sharp diffraction peak corresponding to crystalline phases could be observed in the XRD spectra of Ti42Zr22Mn36 and Ti43Zr29Fe28. While for alloy with Ti44Zr30Co26 no sharp diffraction peak could be found except broad diffraction halos. This result suggests that a critical eutectic temperature in the phase equilibrium for forming glass phase is around 1000°C.
The Correlation between Stacking Fault Energy and the Work Hardening Behaviour of High-Mn Twinning Induced Plasticity Steel Tested at Various Temperatures
Authors: Shterner Vadim , Timokhina Ilana B. , Beladi Hossein
Published: May 2014

High-Mn Twinning Induced Plasticity (TWIP) steels have superior mechanical properties, which make them promising materials in automotive industry to improve the passenger safety and the fuel consumption. The TWIP steels are characterized by high work hardening rates due to continuous mechanical twin formation during the deformation. Mechanical twinning is a unique deformation mode, which is highly governed by the stacking fault energy (SFE). The composition of steel alloy was Fe-18Mn-0.6C-1Al (wt.%) with SFE of about 25-30 mJ/m2 at room temperature. The SFE ensures the mechanical twinning to be the main deformation mechanism at room temperature. The microstructure, mechanical properties, work hardening behaviour and SFE of the steel was studied at the temperature range of ambient≤T[°C]≤400°C. The mechanical properties were determined using Instron tensile testing machine with 30kN load cell and strain rate of 10-3s-1 and the work hardening behaviour curves were generated using true stress and true strain data. The microstructure after deformation at different temperatures was examined using Zeiss Supra 55VP SEM. It was found that an increase in the deformation temperature raised the SFE resulting in the deterioration of the mechanical twinning that led to decrease not only in the strength but also in the total strain of the steel. A correlation between the temperature, the SFE, the mechanical twinning, the mechanical properties and the work hardening rate was also found.
Combined Martensite and Bainite Formation from Austenite Decomposition in HSLA Steel
Authors: da Silva Elisabete Pinto , Xu Wei , Föjer Cecilia , Houbaert Yvan , Sietsma Jilt , Petrov Roumen
Published: May 2014

Recent studies have shown the possibility to induce time-dependent phase transformations during isothermal treatment between the martensite start (MS) temperature and martensite finish (Mf,) temperature, i.e. after initial martensite formation. Such treatments result in specific complex microstructures consisting of bainite, martensite and retained austenite, depending on the holding temperature and time. However, the nature of the isothermal transformations below MS is not completely understood and issues like isothermal formation of martensite and bainite formation are still under discussion. The purpose of this study is to investigate the phase transformations from austenite, subsequent to initial martensite formation, during isothermal treatments at different temperatures of HSLA steel. The microstructure development was monitored by means of dilatometry and microstructural characterization of the transformation products by Optical Microscopy, Scanning Electron Microscope, Electron Backscatter Diffraction and X-ray diffraction. The phase transformations and complex competition and interactions between the different transformation mechanisms are discussed.
Analysis of Recrystallization and Strain-Induced Precipitation on High Nb- and N-Bearing Austenitic Stainless Steel
Authors: Silva Mariana B.R. , Gallego J. , Cabrera Jose María , Balancin O. , Jorge Alberto Moreira
Published: May 2014

The mechanical properties and corrosion resistance of stainless steels are due to the combined effect of chemical composition and thermomechanical processing. The objective of this study was to investigate the interaction precipitation-recrystallization of an austenitic steel with high additions of nitrogen and niobium through continuous-cooling multiple deformation hot-torsion tests. Samples were heated up to a soaking temperature of 1250 oC and kept at this temperature for 5 minutes, and then deformed during cooling. The deformation pass was 0.3 with a strain rate of 1 s-1 and interpass times of 20 or 50 s. The evolution of the microstructure was investigated by optical, EBSD and transmission electron microscopy, using thin foils and carbon extraction replica samples. The results showed that some precipitates were not dissolved after reheating and the presence of niobium-and chromium-rich particles after processing was confirmed. The strain accumulation with the interpass time of 20 s yielded finer precipitation and improved grain refinement than observed after 50 s. Some interaction of the precipitates with dislocations and grain boundary could be evidenced.
Two-Step Brittle-to-Ductile Transitions in Pearlitic Steels
Authors: Sirithanakorn Thiti , Tanaka Masaki , Higashida Kenji
Published: May 2014

The brittle-to-ductile transition in fully pearlitic steels was investigated. The temperature dependence of the absorbed impact energy was measured with the blade speed of 0.0033 m/s. The absorbed energy per unit area increased with two steps as the test temperature increased: the first jump of around 10 kJm-2 at 130 K and the second jump of around 22 kJm-2 at 273 K. The twice jumps of the absorbed energy suggests a two-step brittle-to-ductile transition in fully pearlitic steels. SEM images of side surfaces exhibited that micro-cracks propagated through cementite lamellae at temperatures below only those of the second jump of the absorbed energy, suggesting that the deformability of cementite controls the second jump.
Effect of Cobalt Addition on the Deformation and Recrystallization Textures of Polycrystalline IN713C Nickel Based Superalloy
Authors: Song J.Y. , Sato Shigeo , Koizumi Yuichiro , Chiba Akihiko
Published: May 2014

The aim of this study was to examine the effect of cobalt addition on the deformation and recrystallization behavior. The prepared material was Inconel 713C nickel base superalloy. In order to improve the deformability, the IN713C was modified by cobalt addition with 5 and 10wt%. Mechanical property was determined by room temperature tensile test with the strain rate of 10-3 s-1.The recrystallization was performed at 1473K for 300sec followed by oil quenching. The final microstructure becomes homogeneous through cobalt addition. Strength and work hardening rate were decreased during room temperature tensile test. By contrast, elongation was increased. Nucleation site was changed by cobalt addition. It was found that kinetics of recrystallization is dependent of the cobalt addition. The cobalt addition is attributed with ductility and recrystallization behavior and the latter is related to change of deformation behavior.
Structure, Microstructure, and Selected Mechanical Properties of Ti-Zr-Mo Alloys for Biomedical Applications
Authors: Correa Diego Rafael Nespeque , Kuroda Pedro Akira Bazaglia , Grandini Carlos Roberto
Published: May 2014

New titanium alloys for biomedical applications have been developed primarily with the addition of Nb, Ta, Mo, and Zr, because those elements stabilize the β phase and they don’t cause cytotoxicity in the organism. The objective of this paper is to analyze the effect of molybdenum on the structure, microstructure, and selected mechanical properties of Ti-15Zr-xMo (x = 5, 10, 15, and 20 wt%) alloys. The samples were produced in an arc-melting furnace with inert argon atmosphere, and they were hot-rolled and homogenized. The samples were characterized using chemical, structural, and microstructural analysis. The mechanical analysis was made using Vickers microhardness and Young’s modulus measurements. The compositions of the alloys were sensitive to the molybdenum concentration, indicating the presence of α’+α”+β phases in the Ti-15Zr-5Mo alloy, α”+β in the Ti-15Zr-10Mo alloy, and β phase in the Ti-15Zr-15Mo and Ti-15Zr-20Mo alloys. The mechanical properties showed favorable values for biomedical application in the alloys presenting high hardness and low Young’s modulus compared with CP-Ti.
Effect of Cooling Rate after High Temperature Nitriding on Transformation Microstructure in Low Carbon Steel
Authors: Tsukiyama Kuniaki , Nakada Nobuo , Tsuchiyama Toshihiro , Takaki Setsuo , Tomota Yo
Published: May 2014

High temperature nitriding was applied to a low carbon steel, and then the transformation microstructure formed from the high nitrogen austenite was observed. The microstructure was greatly influenced by cooling rate after the nitriding. The austenite transformed to martensite when the cooling rate was fast (water-cooling) though a certain amount of austenite was retained in the martensite. On the other hand, a diffusional transformation product such as (ferrite + Fe4N) eutectoid structure was formed when the cooling rate was slow (gas- or furnace-cooling). The hardness profile obtained in these specimen were related with microstructure depending on the nitrogen concentration profile and cooling rate.
Constitutive Analysis and Microstructure Evolution of the High-Temperature Deformation Behavior of an Advanced Intermetallic Multi-Phase γ-TiAl-Based Alloy
Authors: Werner Robert , Schwaighofer Emanuel , Schloffer Martin , Clemens Helmut , Lindemann Janny , Mayer Svea
Published: May 2014

In the present study the high-temperature deformation behavior of a caste and subsequently HIPed β-solidifying γ-TiAl-based alloy with a nominal composition of Ti-43.5Al-4Nb-1Mo-0.1B (in at. %), termed TNM alloy, is investigated. At room temperature this alloy consists of ordered γ-TiAl, α2-Ti3Al and βo-TiAl phases. By increasing the temperature, α2 and βo disorder to α and β, respectively. In order to get a better understanding of dynamic recovery and recrystallization processes during thermomechanical processing, isothermal compression tests on TNM specimens are carried out on a Gleeble®3500 simulator. These tests are conducted at temperatures ranging from 1100 °C to 1250 °C (in the α/α2+β/βo+γ phase field region) applying strain rates in the range of 0.005 s-1 to 0.5 s-1 up to a true strain of 0.9. The evolution of microstructure along with the dynamically recrystallized grain size during hot deformation is examined by scanning electron microscopy (SEM). The flow softening behavior after reaching the peak stress in the true stress-true strain curve is attributed to dynamic recrystallization. By using the Zener-Hollomon parameter as a temperature-compensated strain rate the dependence of flow stress on temperature and strain rate is shown to follow a hyperbolic-sine Arrhenius-type relationship.
Bainitic Forging Steels for Cyclic Loading
Authors: Wirths Vera , Wagener Rainer , Bleck Wolfgang , Melz Tobias
Published: May 2014

Light-weight design is one of the main drivers for material development in the automotive industry. For optimum weight reduction new materials and their fatigue behavior under real cyclic service loads have to be taken into account (Gassner test). Currently the casted components made from Austempered Ductile Iron (ADI) show better service fatigue life for variable load cases than some traditional forging steels because of it’s inherent retained austenite. The traditional forging steels are the precipitation hardening ferritic-pearlitic steels (PHFP steel) and the martensitic quenched and tempered (Q&T) steels. The next steel generation for forged components in the drive train might be bainitic steels with an optimized microstructure with respect to cyclic behavior. Depending on the chemical composition and the heat treatment it includes a ferritic primary phase and a secondary phase, which consists of either carbides, martensite, retained austenite or M/A constituents. By alloying of more than 1% Si the formation of cementite will be suppressed and a carbide free bainite (CFB) will be formed. The secondary phase of this CFB contains retained austenite, which has the possibility to close crack tips by local compression stresses due to the transformation to martensite. As a result of this CFB exhibits better cyclic properties than the commonly used forging steels. The materials and process design as well as results of the fatigue behavior will be presented.
Tensile Fracture Characteristics of a Single Crystal Nickel-Based Superalloy
Authors: Wu Dan , Tian Li Xi , Ma Chao Li
Published: May 2014

Tensile fracture behavior of a single crystal nickel-based superalloy with different orientations and temperatures was studied. The tensile fracture surfaces and microstructure were analyzed by field emission scanning electron microscope (FE-SEM). The results showed that, generally, this single crystal nickel-based superalloy exhibited obvious tensile anisotropy. Under the condition of room temperature, the different areas of crack nucleation, propagation and final fracture area were clearly observed and varied greatly in different orientations. At elevated temperature, the fracture surface presented mixed characteristics of holes and dimples and its fracture was dominated by micro-void coalescence. Fracture mechanism was discussed.
Nitrogen-Enhanced Nanostructural Evolution and its Effect on Phase Stability in Biomedical Co-Cr-Mo Alloys
Authors: Yamanaka Kenta , Mori Manami , Chiba Akihiko
Published: May 2014

Nitrogen addition is known to effectively suppress the athermal γ (fcc) → ε (hcp) martensitic transformation of biomedical Co–Cr–Mo alloys and ultimately provides a combination of high strength and good ductility. In this work, the nanostructural evolution and its influence on dislocation slip as an elementary process in the martensitic transformation were investigated to reveal the origin of their enhanced γ phase stability due to nitrogen addition. The biomedical Co–29Cr–6Mo (wt.%) alloys containing nitrogen in different concentrations (0–0.24 wt.%) were prepared. A single phase γ matrix was attained by adding nitrogen contents higher than 0.1 wt.%. We discovered nanosized Cr2N precipitates that form on the {111}γ planes in the N-containing alloy specimens. It was revealed that the nanoscale inhomogeneities function as obstacles to the glide of partial dislocations and consequently significantly retard the γ → ε martensitic transformation. Since the formation of ε martensite plays a crucial role in plastic deformation and wear behavior, the developed nanostructural modification associated with nitrogen addition must be a promising strategy for highly durable orthopedic implants.
Interface Migration with Segregation in MoSi2-Based Lamellar Alloy Simulated by Phase-Field Method
Authors: Yamazaki Toshihiro , Koizumi Yuichiro , Chiba Akihiko , Hagihara Koji , Nakano Takayoshi , Yuge Koretaka , Kishida Kyosuke , Inui Haruyuki
Published: May 2014

MoSi2–based alloys are attracting attention as ultra-high temperature structural material for super-high efficiency gas turbine power generation systems. In this study, the effects of Cr-and Zr-addition on interface migration in MoSi2/NbSi2 lamellar silicide were examined by phase field simulations employing the segregation energies evaluated by the first principles calculation in addition to thermodynamic free energy in order to take into account the chemically-driven interfacial segregation. The simulation results indicate that both Cr and Zr can segregate at the lamellar interface to suppress its migration, and the Zr-addition is more effective to lower the interface migration rate than the Cr-addition owing to its higher segregation energy.
EB-Irradiation Induced Strengthening of Carbon Fiber Reinforced Thermoplastic Polymers
Authors: Yamazaki Yoshiki , Takei Hiroaki , Kanda Masae , Iwata Keisuke , Salvia Michelle , Nishi Yoshitake
Published: May 2014

Carbon fiber reinforced polymers (CFRP), which are typical composite materials, and have been applied as light structural materials with high strength [1, 2]. The further strengthening has been always expected to develop high speed transports with small energy consumption. Although influences of electron beam (EB) irradiation with high energy on the fracture toughness of carbon cross of carbon fibers in thermo-hardened epoxy resin matrix (thermo-hardened CFRP) have been often reported [3], no one has succeeded the strengthening of CFRP irradiated by electron beam. On the other hand, the homogeneous low voltage electron beam irradiation (HLEBI) often induces not only the hardening, high wear resistance and sterilization for practical use of polymer, but also the mist resistance [4–6]. In addition, the irradiation has improved not only the bending fracture strain of carbon fiber [7, 8], but also the deformation resistivity, strength and fracture strain on static tensile test [9]. In our recent research, it has succeeded that the EB-irradiation also enhances the fracture stress and fracture strain of static bending test of thermo-hardened CFRP [10]. Furthermore, the improvement of impact value of thermo-hardened CFRP by EB-irradiation has been also reported to apply to high-speed transports [11]. However, the production rate of thermo-hardened CFRP has been serious problem in mass production.
Interdiffusion and Microstructure Simulation in Ni and Co Based Overlay Coatings on a Ni Based Superalloy at High Temperatures
Authors: Yuan Kang , Eriksson Robert , Peng Ru Lin , Li Xin Hai , Johansson Sten , Wang Yan Dong
Published: May 2014

In turbine engines, Ni or Co based alloys are used at high temperature, either as base materials, superalloys, or deposited on the surface of superalloys, as coatings. In the present study, two different MCrAlY overlay coatings, Ni and Co based, on a Ni based superalloy IN792 were aged for different times in air at three temperatures, 900°C, 1000°C and 1100°C. The aging processes were simulated by using DICTRA software by focusing on the interdiffusion behavior in the superalloy-coating systems. The results of simulation captured the main microstructural features observed and were used to analyze the diffusion behavior of alloying elements and the corresponding microstructure development. It was found that coating composition and temperature affected significantly the microstructure near the superalloy-coating interface, and their relations were mapped as a summary.
Effect of Grain Size on Cryogenic Mechanical Properties of an Al-Mg-Sc Alloy
Authors: Zhemchuzhnikova Daria , Kaibyshev Rustam
Published: May 2014

An aluminum alloy with a chemical composition of Al–6%Mg–0.35%Mn–0.2%Sc–0.08%Zr–0.07%Cr (in wt.) and an initial grain size of ∼22 μm was subjected to equal-channel angular pressing (ECAP) at 593 K up to a total strain of ~12. Extensive grain refinement provided the formation of fully recrystallized structure with an average grain size of ∼0.6 μm. The mechanical properties of the alloy in two different structural conditions were examined at temperatures ranging from 77 to 293 K. It was shown that ECAP highly enhanced the strength, ductility and fracture toughness of the material over the wide temperature interval. Positive effect of grain refinement tends to increase with decreasing temperature due to suppression of brittle intergranular fracture. At ambient temperature, the extensive grain refinement provides +65% increase in yield stress (YS) and ductility, concurrently. At 77 K, YS increase is + 77%, and the ductility increase is +113% owing to grain refinement. Effect of the grain size on fracture toughness at cryogenic temperatures is discussed.
New Generation TMCP Technology and its Application to 960 MPa High Strength Structural Steel Plates
Authors: Wang Zhao Dong , Zhu Jin Bao , Deng Xiang Tao , Wang Bing Xing , Tian Yong , Wang Guo Dong
Published: May 2014

The new generation thermo-mechanical controlled processing (TMCP) technology based on advanced cooling technique and equipment is introduced here in the context of 960MPa grade high strength structural steel plates. This new technology accurately controls the cooling rate and temperature, with strong influence on phase transformation and precipitation including microstructure and mechanical properties of the steel. The application of the newly developed technology applied to the production of 960MPa grade high strength structural steel demonstrated its effectiveness, especially in improving low temperature impact toughness. The yield strength was 980~1000 MPa and tensile strength 1080~1200 MPa, with impact toughness approaching 150J at-40°C.Keywords: New generation TMCP technology; Ultra fast cooling process; high strength steels; mechanical properties
Variable Frequency Microwave Curing of SU8 Photoresist Films
Authors: Antonio Christian , Watanachai Piyachat
Published: May 2014

Photoresist used in the fabrication of Microelectrochemical Systems (MEMS) has traditionally been processed using conventional curing technology. This type of curing is often time intensive and results in non-uniform products. A uniform bake of the layer is not always possible due to the mechanisms of heat transfer conventional curing offers, leading to poor pattern resolution, formation of micro-cracks and severe outgassing occurring as a consequence. The Variable Frequency Microwave (VFM) Technique was successfully utilised in this study as an alternative method for the processing of negative tone SU8 photoresist. The VFM method was compared to the conventional processing method, which utilises a Hotplate, and a hybrid method utilizing both Hotplate and the VFM and found that an increase on the degree of cure was observed using the VFM at similar processing temperatures which means that SU8 curing at lower temperatures or rapid curing is possible. The increase in cure rates can be attributed to a combination of heat transfer and the unique capability of microwave to couple with the sample. Optical studies of the microstructures fabricated suggest that films that have a degree of cure of <60% resulted in poor quality microstructures. The VFM was found to achieve satisfactory microstructures at most of the temperatures tested as compared to the other two methods tested.
A Solid Oxide Fuel Cell Micro-Scale Modeling with Cylindrical Particle Shaped Electrodes
Authors: Saisirirat Penyarat
Published: May 2014

A micro scale model of a solid oxide fuel cell (SOFC) involving the mass transfer together with the electrochemical reaction, the electron and ion transports through respective cylindrical shaped electron-and ion-conducting particles inside the electrodes was mathematically developed. The predicted cell performance was showed according to the operating and design condition. The effects of micro-scale electrode geometry on the cell performance were also taken into account. This present study reveals the working mechanisms of SOFC at the micro-scale level, while demonstrating the use of micro-scale relations to enhance the SOFC performance. The accuracy of the presented model was validated by comparing to already existing experimental results from the available literatures.
Enhancing the Flexural and Impact Properties of Bioplastic Poly(lactic acid) by Melt Blending with Poly(butylene succinate)
Authors: Lertwongpipat Naphaporn , Petchwatana Nawadon , Covavisaruch Sirijutaratana
Published: May 2014

Bio-based biodegradable Poly (lactic acid) (PLA) suffers limitations such as brittleness and slow crystallization. This study aims to resolve the brittle nature of PLA by blending with Poly (butylene succinate) (PBS), a more ductile biodegradable polymer with superior toughness and flexural properties. In this research, a series of PLA/PBS blends was prepared at the blend ratios of 100/0, 80/20, 60/40, 40/60, 20/80 and 0/100. FTIR showed that there was no change in the functional groups of the PLA/PBS blends. Thermal stability assessed by TGA revealed that PBS degraded at higher temperature than that of PLA; the decomposition temperature (Td) at 10% weight loss of PLA and PBS were 330.8 and 356.4°C respectively. The Td of all the blends increased gradually with the addition of PBS. The flexural properties in terms of the flexural strength and the flexural modulus of the blends reduced significantly with PBS content. The PLA/PBS specimens with greater PBS content were softened and flexed more easily, thereby requiring a much lower flexural strength. The flexural modulus of the 80/20 and 60/40 blends dropped from 3.5 GPa for neat PLA to 3.2 GPa and 2.1 GPa while the flexural strength also declined from 105.3 MPa to 90.9 MPa and 69.1 MPa respectively. The toughness of all the blends was greater than that of neat PLA; in particular the 60/40 blend exhibited superior impact strength of 48.7 J/m compared with 30.9 J/m of the neat PLA. The microscopic images of all the blends showed two distinct phases; the 60/40 blend consisted of well dispersed small particles of the tough PBS, resulting in greater absorption of energy upon impact.
Prospects of Carbon Based Micro-Fluid Electrolyte for the Vanadium Redox Flow Battery (VRB)
Authors: Tantisakon Theerapab , Holasut Kanyarat
Published: May 2014

The effects of carbon black particle dispersed in the electrolyte and used in a modified VRB which was traditionally used of carbon felt as electrode has been removed were studied. The adding of the carbon black particle reduced both activation overpotential and ohmic overpotential especially at low OCV. The functional group on the surface of the carbon black particle helps to increase the rate of reaction which results in the reduction of activation overpotential. When the electrolyte with the carbon black particle dispersed flows into the cell, it is possible that some of carbon particles settle on the surface of current collectors and this effectively increases the surface area of current collectors. Hence, it reduces the ohmic overpotential.
Extractive Fermentation of Ethanol from Fresh Cassava Roots Using Vacuum Fractionation Technique
Authors: Phakping Supathra , Ketudat-Cairns Mariena , Boontawan Apichat
Published: May 2014

Fresh cassava roots were used as a raw material for ethanol fermentation. Conventional batch mode (CF), simultaneous saccharification and fermentation (SSF) and simultaneous liquefaction, saccharification and fermentation (SLSF) were investigated with various enzyme systems. The ethanol concentrations obtained in batch fermentations ranged from 8-12 wt%. In addition, vacuum fractionating technique was successfully introduced to simultaneously remove high purity ethanol from fermentation broth in batch mode. The distilled ethanol concentration was approximately 86 wt% whilst its concentration in the bioreactor was kept lower than 2 wt%. As a result, the product inhibition effect to yeast cells was reduced.
Biogas Production from Human Faece and Community Waste Food
Authors: Poocheera Sahassawas , Suntivarakorn Ratchaphon , Treedet Wasakron
Published: May 2014

This research had an aim to study the biogas production from human faece and community waste food using batch fermentation process. In this experiment, there were 5 types of ratio between human faece and community waste food which were 1:0, 2:1, 1:1, 1:2 and 0:1 and the raw material is dilute with water in the ratio 1:4. The biogas digester was clear plastic cylindrical tank of 20 liters, base area of 300 square centimeters and height of 30 centimeters. This experiment was performed to analyze the rate of gas generation before and after the biogas composition fermentation and heating value of biogas. It was found that, in the ratio 2:1 of human faece and community waste food, the rate of biogas generation was the highest. In the ratio of 1:0, the methane gas generation was the highest which the gas methane composition is 67.6% higher than the of other animals manure, the rate of biogas generation was 0.59 m3/kg-VS and the heating value was 24,336 MJ/Nm3.
Cultivation of Chlorella sp. Using Industrial Effluents for Lipid Production
Authors: Sasibunyarat Tarinee , Cheirsilp Benjamas , Charnnok Boonya , Chaiprapat Sumate
Published: May 2014

This work aims to investigate microalgal growth and lipid production fromChlorellasp. on different digester effluents from seafood factory, starch factory and palm oil mill. Results under 32 cultivation days showed that the effluent from seafood factory gave the highest microalgal growth (0.9956±0.2121 g/L) followed by starch factory and palm oil mill (0.8622±0.0391 and 0.2611±0.0444 g/L, respectively). Although higher nitrogen and phosphorus in medium stimulated growth, turbidity of the palm oil mill effluent showed a negative impact. In addition, phosphorus concentration in the medium positively affected the lipid content in cells. The seafood effluent with total phosphorus of 45.24±3.80 mg/L yielded highest lipid content at 26.96±1.58% compared to starch factory (22.10±2.61). The digester effluent from seafood factory was found more suitable forChlorellasp. cultivation due to the high mass production, oil content and lipid productivity.
The Design of Total Knee Replacement Prosthesis Suitable for Anteroposterior Movement for Thai Female
Authors: Piyasin Surasith , Nabudda Kriengkrai , Hemathulin Suwipong
Published: May 2014

Nowadays, patients with osteoarthritis in Thailand are likely to increase in number every year. There are approximately 462,000 people and most are females than males. The treatment is surgery knee replacement implants which must be imported from abroad and cost is expensive.Total knee prosthesis used in Thailand would not fit with the body of the Thai women because of the design total knee prosthesis use anatomical data of Europe and designed for both male and female, which is different in the knee structure. This research aims to study the size and shape of knee for Thai women and design total knee replacement. The using of finite elements is to assist in the analysis which focuses on the influence of the force active on and the effects of stress distribution on the part of the knee at different stages of gait cycle. The results of the study can measure the average size of Thai knee women base on analytical data. Anthropometric data on the proximal tibia and distal femur of 55 female knees were obtained using three dimensional computer tomographic measurements. The parametric studies are dimension analysis of the femoral mediolateral (fML) and femoral anteroposterior (fAP) dimension on distal femur surface and tibial mediolateral (tML), tibial anteroposterior (tAP) on proximal tibia surface. The measuring average values are 65, 60, 67 and 45 mm respectively. All parameters were compared to the size of the total knee prosthesis which currently used in Thailand. It is found that values are 70, 62, 68 and 48 mm respectively which is larger than the average Thai woman.The study of finite elements can be made aware of the stress distribution and stress in the area of artificial knee while walking and leading to the design of artificial knee joint to have size and shape suitable for Thai women.
CFD in Continuous Stirred Tank: Comparison between Rushton and Paddle Turbines
Authors: Srirugsa T. , Prasertsan S. , Theppaya T. , Leevijit T. , Prasertsan P.
Published: May 2014

Biogas produced from palm oil mill effluent (POME) is common in Thailand. A 2-step digestion system, which consists of a continuous stirred-tank reactor (CSTR) and a UASB, is being implemented for biohythane (biohydrogen and biomethane) production. This paper describes three-dimensional computational fluid dynamics (CFD) simulations of POME flow in a laboratory-scale CSTR. The study focuses on comparisonof impellers, the Rushton and the paddle turbines, for the best POME mixing with minimum loss of granules. The result of flow patterns in CFD showed that better mixing in the bottom through the middle of the tank can be achieved by proper selection of impellers and baffles to avoid the loss of granules by effluent.
Heat Transfer Improvement in a Square Duct with Diagonal Inclined Ribs
Authors: Suwannapan Supattarachai , Poomsalood Ratsak , Promvonge Pongjet , Jedsadaratanachai Withada , Limkul Thitipat
Published: May 2014

This research presents a numerical study of turbulent periodic flow and heat transfer in threedimensional isothermalfluxed square duct with diagonal inclined rib inserted. The fluid flow and heat transfer characteristics are presented for Reynolds numbers in the range of 4000 to 20,000. The computations based on the finite volume method, and the SIMPLE algorithm has been implemented. Effects of rib pitch ratios (0.5 to 2) at a single blockage ratio of 0.2 and attack angle of 60o on heat transfer and friction factor in the duct are examined and their results of the inclined rib are also compared with those of the smooth duct. It is found that the inclined rib provides higher heat transfer rate and friction factor than the smooth duct for all cases. In addition, the decreasing of the pitch ratio leads to the rise in the Nusselt number and friction factor.
Effect of Sr Doped La4Ni3O10±δ as a Cathode for IT-SOFC
Authors: Chokkha Siriwan , Kuharuangrong Sutin
Published: May 2014

The effect of Sr doped La4-xSrxNi3O10±δ (x = 0, 0.05, 0.1, 0.2 and 0.3) has been investigated as an intermediate temperature SOFC cathode material. The Ruddlesden-Popper (RP) compositions of n = 3 were successfully synthesized via citrate gel method. The single phase of sintered La4-xSrxNi3O10±δ (x = 0, 0.05, 0.1 and 0.2) powders was confirmed as an orthorhombic structure. However, this structure changes to more symmetry with an increasing amount of Sr dopant. With x = 0.3, the phases of La1.7Sr0.3NiO4 as n = 1 RP and NiO appear without n = 3 RP. La3.95Sr0.05Ni3O10±δ shows the highest electrical conductivity with a value of 140 S/cm at room temperature. Nevertheless, the electrical conductivity of La4-xSrxNi3O10±δ decreases and further decreases with increasing amount of Sr. The conductivity values at 200°C of La4-xSrxNi3O10±δ (x =0, 0.05 and 0.1) are 89, 113 and 101 S/cm, respectively. For x = 0.3, the conductivity decreases lower than x 0.1 with its value of 36 S/cm because of the low conductivity phase of n = 1 RP.
Experimental Study on Flow Friction and Heat Transfer in a Square-Duct Heat Exchanger with Winglet Turbulators
Authors: Suwannapan Supattarachai , Hoonpong Panuwat , Promvonge Pongjet , Juengjaroennirachon Sirisawat , Pimsarn Monsak
Published: May 2014

The paper presents an experimental study on airflow friction and heat transfer behaviors in a heat exchanger square-duct fitted with winglet turbulators. The experiments are carried out by varying the airflow rate in terms of Reynolds number from 4000 to 25,000. The winglets were mounted in tandem with three attack angles (α=30o, 45o and 60o), two winglet-pitch to duct-height ratios, (called pitch ratio, PR=P/H=1.0 and 1.5) and a single winglet-to duct-height ratio, (called blockage ratio, BR=e/H=0.2). Effects of the winglet parameters on heat transfer and pressure loss in terms of Nusselt number and friction factor are investigated. The experimental result reveals that the application of the winglets provides considerably higher heat transfer and pressure loss values than the smooth duct alone. The winglet at α=60o and PR=1 gives the maximum heat transfer and pressure loss but the one at α = 30o and PR=1.5 yields the highest thermal enhancement factor of about 1.49 at the lowest Reynolds number.
Heat Transfer Augmentation in a Round Tube with 60o Winglet Pair Inserts
Authors: Chokphoemphun Suriya , Tongyote Pattarapan , Promvonge Pongjet , Jedsadaratanachai Withada , Chompookham Teerapat
Published: May 2014

The experimental study on heat transfer enhancement in a tubular heat exchanger fitted with 60o winglet pairs is carried out by varying airflow velocity in turbulent region in the test section having a constant wall heat-flux. Effects of three blockage ratios (BR=e/D= 0.1, 0.15 and 0.2) and three pitch ratios (PR=P/D= 1, 1.5 and 2) of the winglet pairs on heat transfer rates in the terms of Nusselt number (Nu) and pressure loss in the form of friction factor (f) are examined. The experimental results illustrated that the tube with winglet pair insert provides the heat transfer rate higher than the smooth tube around 1.7 to 2.6 times, depending upon operating conditions. The thermal enhancement factor for using the winglet-pair turbulator is in a range of 1.03 - 1.31.
Heat Transfer Enhancement in a Solar Air Heater Channel with Discrete V-Baffles
Authors: Soodkaew Prawat , Skullong Sompol , Promvonge Pongjet , Pairok Watanyu
Published: May 2014

This article presents the study of heat transfer enhancement in a uniform heat-fluxed channel fitted with discrete V-shaped baffles. The experiments are carried out by varying airflow rate for Reynolds number ranging from 4100 to 22,000. The V-baffles with relative height ratio, e/H = 0.15 and the attack angle, α = 45o, are mounted repeatedly on the upper plate only, similar to an absorber plate of solar air heater systems. The effects of four baffle-pitch to channel-height ratios (PR= 0.5, 1.0, 1.5 and 2.0) on heat transfer in terms of Nusselt number and pressure loss in the form of friction factor are experimentally investigated. The experimental results show that the use of the discrete V-baffles leads to a considerable increase in Nusselt number and friction factor in comparison to the smooth channel alone. The V-baffled channel with PR=0.5 provides the highest heat transfer, friction factor and thermal enhancement factor.
Investigation of Flow and Heat Transfer Characteristics of Annular Impinging Jet
Authors: Musika Watchara , Wae-Hayee Makatar , Vessakosol Passakorn , Niyomwas Banyat , Nuntadusit Chayut
Published: May 2014

Flow and heat transfer characteristics of impinging jet from annular pipe were experimentally and numerically investigated. To generate annular jet, the cylindrical rod with 12.7 mm in diameter was inserted at center of pipe nozzle which has inner diameter (D) of 28.6 mm. The jet-to-plate distance (H) was examined in the range of 2D, 4D, 6D and 8D. The jet Reynolds number was fixed for all experiments at Re=20,000 based on averaged velocity and pipe inner diameter. The conventional jet was also studied for comparison. The temperature distribution on the impingement surface was measured using an infrared camera. The numerical simulation was carried out to visualize the flow behavior. The results show that the heat transfer of annular jet is higher than that the case of conventional pipe jet at low jet-to-plate distance (H=2D); however, the ones of annular and conventional jet are comparable when jet-to-plate distance becomes higher than H=6D.
Controlling Robots Using Thai Speech Recognition
Authors: Phanprasit Tanasak
Published: May 2014

Maximum security is essential for a robotic device to achieve its optimum control. In this research, we present robotic motions, controlled by technological speech recognition techniques, using commands of Thai Speech Recognition (TSR). Examples of such speech words used are; Sai, Khwa, Na, Lang Khun, Long and Yood, which are the equivalent English language representations for; turn left, turn right, forwards, backwards, upwards, downwards, and stop, respectively. The speech commands are independent for any particular user and so, as a result, they are highly beneficial for general and practical use. The three main important parts of this paper comprise; Pre-processing, Discrete Fourier Transform (DFT), and Back Propagation Neural Network (BPN). The experimental results, when reviewed, exhibit results showing that the average accuracy percentages are equal to 71.00% for female commands, and 70.00% for male commands, respectively.
Design, Constructand Performance Evaluation of a 2-Stage Parabolic through Solar Concentrator in Pathumthani
Authors: Sookramoon Krissadang
Published: May 2014

This research presents the design, construct and performance evaluation of a 2-stage parabolic trough solar concentrator (2-stage PTC). The primary stage was constructed of polished stainless steel (SUS 400) to form the primary stage parabolic reflector (1.489 m ×1.489 m size), the second stage was constructed of multi piece mirror to form the hyperbolic shape reflector (0.13 m×1.489 m). Black painted copper pipe in the size of inside diameters (27.2 mm) covered with glass tube was used as receiver. One axis Sun tracking system has been installed to track 2-stage PTC according to the direction of beam propagation of solar radiation. By using water as a heat transfer fluid its capability to heat transfer and load high temperature (100°C). The storage tank is fabricated with stainless steel of size 40 L. The experimental tests have been carried out in Faculty of Industrial Technology, Vallaya Alongkorn Rajabhat University Pathum Thani, Thailand climatic conditions (14.134°N, 100.611°E) during 5 selected days of the months May 2013. The performance of a 2-stage PTC was evaluated using outdoor experimental measurements including the useful heat gain, the thermal instantaneous efficiency and the energy gained by the water. The experimental results shown the maximum thermal efficiency was 23.43%, the optical efficiency was 76%, and the total geometrical concentration was 27.08X.
Tangible Programming for Basic Control System New Frameworks to Engineering Education for Children
Authors: Meadthaisong Thiang , Meadthaisong Siwaporn , Chaowaskoo Sarawut
Published: May 2014

Programming control in industrial design is by its nature expert upon an example being Programmable Logic Controller (PLC). Such programmes are unsuitable for children or novices as they cannot understand how to use the programme. This research seeks to present tangible programming for a basic control system in new frameworks in engineering education for children. Such programmes could be for use in kindergartens, primary schools or general teaching where knowledge about basic control is required. Normally open-loop and closed-loop control system programming is taught at university and college level. This may be late as far as acquiring knowledge of basic control systems is concerned. Using tangible programming without a computer but instructions and interface, relay and motor could result in children in kindergartens and primary schools being able to programme open-looped control systems which mix chemicals or closed-loop control systems which control conveyor belts. However, the children would not be able to undertake programming using programmable control in a similar scenario.