bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity Improvement of Conducting Polymer Based Sensor to Vehicle Emission Gas by Using Imprinting Method
Authors: Aba La , Sudiana Inyoman Nyoman , Mongkito Vivi Hastuti R.
Published: August 2015

Sensitivity improvement of gas sensor based on conducting polymer of Poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS) thin layer to motor vehicle emission gas has been studied. The PEDOT:PSS thin films were deposited on FR4 substrates by using a spin-coating technique. Then, the imprinting process of gas sensor was performed by injecting motor vehicle emission gas into the spin-coating chamber. Finally, the gas sensor was dried on a controllable hot plate. Sensor characterization was done by measuring the electrical properties and responses of the sensor to motor vehicle emission gas. Characterization of the sensor response was done by flowing gas in the gas chamber in which the sensor was placed. The results showed that imprinted PEDOT:PSS thin layer-based gas sensor has short response and recovery time, a good repeatability and higher sensitivity to motor vehicle emission gas. To this end, we found that imprinting method on the surface of PEDOT:PSS thin layer can improve the sensitivity of the sensor to motor vehicle emission gas.
Shellac Coated Hydroxyapatite (HA) Scaffold for Increasing Compression Strength
Authors: Triyono Joko , Susmartini Susy , Susilowati Endang , Murdiyantara Suci Anindya
Published: August 2015

This work reports on the effect of shellac coated hydroxyapatite (HA) on the compression strength. The HA was processed from bovine bone. Shellac was derived from the resinous secretion of the lac insect. The aims of the addition of shellac solution is to improve the mechanical properties of the material, especially when this material is implanted as a bone filler in order to not easily broken.The four different of shellac solutions (2,5%; 5%; 7,5%; and 10% weight) coated HA scaffold and one ratio as a control. It was found that the compression strength is influenced by the shellac solution. The greater of shellac solution will increase the compression strength of HA. The highest compression strength ​​was obtained in a solution of 10%.The morphology of HA scaffold was analyzed by Scanning Electronic Microscopy (SEM).
Effect of Aging on Mechanical Properties of Natural Rubber Latex Products Filled with Alkanolamide-Modified Cassava Peel Waste Powder (CPWP)
Authors: Harahap Hamidah , Hartanto Adrian , Hadinatan Kelvin , Surya Indra , Azahari Baharin
Published: August 2015

The effect of aging on mechanical properties of natural rubber latex (NRL) products filled with alkanolamide-modified cassava peel waste powder (CPWP) was studied. CPWP used as fillers was prepared by milling and sieving it until the size of 100 mesh. The powder then was dispersed in a suspension containing water and alkanolamide in order to modify the prepared powders. The dispersion system of 10 pphr (part per hundred rubber) then was added into NRL matrix followed by pre-vulcanization at 70°C for 10 minutes. The NRL compound then were casted into films by coagulant dipping method then dried at 120°C for 10 minutes. Afterwards, the films were allowed to cool at room temperature for 24 hours before being aged in a circulation of hot air for 24 hours at 70°C. The properties such as tensile strength, tensile modulus, and elongation at break were evaluated between the aged samples and the unaged samples. From this study, it showed that the aged films have increasing value of tensile strength and tensile modulus while the value of elongation at break decreases. These datas are supported by Scanning Electron Microscope (SEM) micrographs which indicate that the change of morphology in NRL films occurs before and after aging.
Application of Serpentine Flux Path Method into a Magnetorheological Valve by FEMM Simulation
Authors: Abd Fatah Abdul Yasser , Mazlan Saiful Amri , Zamzuri Hairi , Abdul Rahman Mohd Azizi
Published: August 2015

Magnetorheological (MR) valve is one of the basic ways to apply and accommodate the MR fluid (MRF) into most of hydraulic applications. MRF can change its rheological properties controllably, reversibly and instantaneously by exposing it to the magnetic field, where the viscosity of the fluid increased variably proportionate to the intensity of the magnetic field applied to the fluid. Within the MR valve, the region where the MRF is allowed to be flown and exposed to the magnetic field is called the effective region, and the longer the effective region is in the MR valve, the higher the pressure drop can be, which means that the valve can withstand higher pressure from input and output of the valve. Hence, lots of studies and previous researches have been focused on improving the performance of MR valve by elongating the effective region in the valve. This paper presents one of the ways to increase the effective region in the MR valve by using the serpentine flux path method. This method is a way to weave the magnetic flux into the effective region of MR valve by alternating the magnetic and non-magnetic materials to guide the magnetic flux to be exposed into the effective region. In this paper, the method is simulated by using Finite Element Method Magnetics (FEMM) software for analyzing the magnetic flux path and flux density in the valve, to see the various effects of length and gap size of effective region, electromagnetic circuits and geometrical placements of magnetic and non-magnetic materials in the valve before it can be applied into real hardware for experimentation.
Transition Insulator-Metal and Antiferromagnetic-Paramagnetic Cu Doped in La0.47Ca0.53MnO3
Authors: Gunanto Yohanes Edi , Sinaga K. , Kurniawan B. , Poertadji S. , Tanaka H. , Ono T. , Steven E. , Brooks J.S.
Published: August 2015

The study of the perovskite manganites La0.47Ca0.53Mn1-xCuxO3 with x = 0, 0.06, 0.09, and 0.13 has been done. The magnetic structure was determined using high-resolution neutron scattering at room temperature and low temperature. All samples were paramagnetic at room temperature and antiferromagnetic at low temperature. Using the SQUID Quantum Design, the samples showed that the doping of the insulating antiferromagnetic phase La0.47Ca0.53MnO3 with Cu doping resulted in the temperature transition from an insulator to metal state, and an antiferromagnetic to paramagnetic phase. The temperature transition from an insulator to metal state ranged from 23 to 100 K and from 200 to 230 K for the transition from an antiferromagnetic to paramagnetic phase.
Relaxation Processes Features of Glass-Forming Melts on the Basis of Copper
Authors: Konashkov Viktor V. , Tsepelev Vladimir S. , Povodator Arkadi
Published: August 2015

Two samples of industrial alloys on the basis of copper are experimentally studied. These alloys are used for production of amorphous solders. The main studied property is kinematic viscosity of metal melt in a liquid state. Data of viscosity dependences from temperature when heating and the subsequent cooling are obtained. Besides, viscosity dependences at constant temperatures from time are received. On viscosity dependences from temperature, for the same samples, abnormal sites and a divergence of curves of heating and cooling are found. On viscosity dependences from time, at a constant temperature, instability is found. The conclusion is drawn that the revealed features are connected with complexity of relaxation process of the studied fusions.
Study Regarding the Influence of Different Antiseptic Mouthwashes on Surface Roughness of Traditional Glass Ionomer Cements
Authors: Stoleriu Simona , Andrian Sorin , Pancu Galina , Nica Irina , Sandu Andrei Victor , Iovan Gianina
Published: August 2015

The aim of the study was to evaluate the surface hardness of two different traditional glass ionomer cements after their exposure to two commercial oral rinsing solutions. Fuji IX GP (GC Corporation, Tokyo, Japan) and Ketac Molar Easymix (3MESPE, Germany) were used in the study. Twenty-one cement samples of each material were split in three groups. In control group the samples were stored in artificial saliva (AFNOR NF S90-701) for 14 days. In groups 2 and 3 the samples of each material were immersed in Listerine and in Corsodyl two times on a day for 14 days. Between the immersion periods the samples were stored in artificial saliva. The samples were subjected to microhardness evaluation using digital microhardness tester (Micro-Vickers Hardness System CV-400DMTM, CV Instruments Namicon). Significant results were obtained when compared the surface hardness of both glass ionomer cements after their immersion in Listerine and in Corsodyl to control group. The surface hardness of Fuji IX in control and in study groups was significantly higher when compared to Ketac Molar Easymix In the conditions of the study, Listerine and Corsodyl decreased the surface hardness of Fuji IX GP and Ketac Molar Easymix glass ionomer cements.
Mechanical and Thermal Performance of Straw Bales
Authors: Moga Ligia
Published: August 2015

Ecological houses have become very popular lately due to an increasing concern regarding the reduction of the CO2 emissions generated by the building sector. An ecological house is perceived as a building that enhances the environment rather than degrading it. Straw bale houses are considered to be an ecological and energy efficient solution to the traditional houses. The research aimed to evaluate the use of straw bale in constructions. The experimental work included the mechanical and the hygrothermal behaviour of straw bale, i.e. compression test, moisture content and thermal conductivity determination on a straw bale wall placed in climatic conditions specific for Romania. The research results show a better thermal performance than some of the traditional choices existing on the market. The study provides encouraging insight into considering straw bale solutions as a first alternative to the classical ones.
Physico-Chemical Parameters in Mountain Freshwater: Cuejdi River from Eastern Carpathians, Romania
Authors: Mihu-Pintilie Alin , Romanescu Gheorghe , Stoleriu Cristian Constantin , Breabăn Iuliana Gabriela
Published: August 2015

Spatial and seasonal variation of physico-chemical parameters of mountain streams is influenced by anthropogenic pollution pressure. The assessment of Cuejdi river water quality from Stânişoarei Mountains through 13 parameters, was performed. 30 samples each were collected during spring and autumn of 2013/2014, measurements being made both in situ aquatic ecosystem (Multi 350i / SET WTW) and in laboratory (bench meter Hanna HI 4421, Titroline 700 SI Analytics and WTW Turb 555IR).
Innovative Synergistic Valorization of Lignite Fly Ash and Steel Industry Scrap-Soil as Secondary Resources for Compacted Ceramics
Authors: Karayannis V. , Papapolymerou G. , Zaoutsos S. , Lamprakopoulos S. , Ntampegliotis K. , Spiliotis X.
Published: August 2015

In the present research, the combined utilization of fly ash (FA), derived from a lignite-fed power station, along with scrap-soil (SS), a steel industry by-product, is investigated, for the development of eco-friendly ceramics, thus enhancing innovation and sustainability. The valorization of these low price and largely available industrial secondary resources as 100% the raw materials mixture in ceramic industry arises interesting technological, environmental and economical benefits. FA and SS were mixed in various proportions (0-70%wt. in SS), cold compacted at 20 tn load using an automated hydraulic press to form a series of 5 cm diameter disc-shaped specimens, and finally sintered at three different peak temperatures (1000oC, 1100oC and 1140oC) for 3h. Then, the specimen microstructure and physico-mechanical properties were characterized. According to the experimental results, a sintering temperature increase from 1000°C up to 1140oC significantly improves specimen densification, thus sharply enhancing the diametral tensile strength (DTS), from 0.5 MPa up to 12.8 MPa respectively for a 50-50%wt. FA-SS mixture. Mechanical strength also varies with the SS percentage in the raw materials. Physico-mechanical properties seem to be constant for specimens containing SS up to 60% at 1140oC.
Removal of Iron and Total Chromium Contaminations in Landfill Leachate by Using Electrocoagulation Process
Authors: Mahmad Mohd Khairul Nizam , Mohd Arif Zainol Mohd Remy Rozainy , Abustan Ismail , Baharun Norlia
Published: August 2015

This research work involves the study removal of Iron and Total Chromium by electrocoagulation process. This project focused on leachate landfill from Pulau Burung, Nibong Tebal, Penang as an electrolyte solution. These heavy metals are the main factor contributing to pollution in leachate landfill. Types of electrodes used in this study were Aluminium (grade 5052) and Stainless Steel (grade 316). The ranges of initial pH applied were pH (3, 4, 5, 6 and 7) and voltages applied were 1.5V, 2.0V and 2.5V. These three parameters were evaluated and the operation time was 60 minutes. At the end of electrocoagulation process, the solutions were stored and analysed using AAS to determine the final concentration of electrolyte solution.
Review of Soil Stabilization Techniques: Geopolymerization Method one of the New Technique
Authors: Hamzah Hazamaah Nur , Al Bakri Abdullah Mohd Mustafa , Heah Cheng Yong , Arif Zainol Mohd Remy Rozainy , Kamarudin Hussin
Published: August 2015

This paper studies the effectiveness of soil stabilizer on the problematic soil or soft soil. It is subjected to instability and massive primary and long term consolidation settlements when subjected to even moderate load increases. The purpose of this study is to review the techniques and materials that have been used in the soil stabilization by previous researchers. The performance of the soil stabilizer for stabilization by means of strength has been highlighted in this study. Unconfined compressive strength (UCS) test was carried out on stabilized soil samples and the results that obtained were discussed. The use of these techniques and materials may provide an inexpensive and advantageous construction process. As a conclusion, the strength of soil can be increased by using these materials and techniques in soil stabilization. This paper gives a comprehensive report on stabilization techniques and materials that have been used for soft soil and also discuss the potential of geopolymerization technology to be one of the new soil stabilization techniques.
Design Practitioner Perception in Determining the Terminology of Biomimicry, Anthropomorphised and Semantic (BAS) in Design Application
Authors: Rosli Muhamad Farizuan , Abdullah Mohamad Hariri
Published: August 2015

This paper focuses on the perception of the design practitioner about the terminology design of Biomimicry, Anthropomorphism and Semantic (BAS). This paper also shows the level of understanding design practitioner in evaluating and reviewing the terminology in design. In the world of design, the various elements incorporated into each design to meet the demand and give effect in developing products. For creative designer, ideas, creativity and in-depth knowledge of design can help them in producing designs and elements needed. As a designer, they have own perception in the interpretation of a design. This paper also discusses the level of understanding of the design practitioners in evaluating and reviewing the terms of design. The analysis results also clearly show the level of understanding of the design practitioner in identifying terms BAS.
The Study of Ornamental Gildings in Old Tempera Icons from the XVIII-th Century
Authors: Munteanu Marius , Sandu Ion , Vasilache Viorica , Sandu Irina Crina Anca
Published: August 2015

The paper presents the study of old ornamentation techniques used into making of two icons from the XVIII-th century, part of the heritage of Tazlau monastery, Neamt County. In order to do this, the materials used to create the polychrome layers and their current conservation state was analyzed. The data obtained by investigating the two mentioned elements have allowed for the identification of different traditional techniques, used for ornamental gilding. Optical microscopy (OM) and Scanning Electron Microscope coupled with Energy Dispersive X-ray spectroscopy (SEM-EDX) were employed in the analyses. The archaeometrical characteristics of the pigments and binders, collaborated with the aesthetic analyses, allowed the dating of the two icons for the end of the XVIII-th century.
Study of an Old Coin Set Using Nondistructive Techniques
Authors: Vasilache Viorica , Cotiugă Vasile , Sandu Ion , Plăcintă Tiberiu Theodor , Mircea Otilia
Published: August 2015

The paper presents the chemical composition and mineralogical distribution of the corrosion crust, more so the chemical composition and the texture of the metallic core on three silver coins dating from the seventeenth century, discovered in various tombs in the necropolis belonging to the former Stratenia Church from Iasi. These were examined by the corroboration of optical microscopy, electron microscopy coupled with X-ray diffraction (SEM-EDX) and the micro-FTIR techniques. The data allowed to establish the main alloy and of the evolutionary contexts during the laying period, based on the texture of the metallic core and on the layout of corrosion products.
Comparative XRD and Microstructure Analysis on Biodegradable Mg-Si-Ca Alloys
Authors: Istrate Bogdan , Crimu Carmen Iulia , Stanciu Sergiu , Oprisan Bogdan , Munteanu Corneliu
Published: August 2015

Biodegradable materials are considered to be the third generation of biomaterials. The aim of these biodegradable alloys is to provide healing and tissue regeneration of the bone. In recent years new types of BM, such as Mg-Si-Ca based alloys were developed and are considered promising candidates for implant materials during a limited time. The effect of Si and Ca addition on pure magnesium alloy has been investigated. The results showed the formation of an intermetallic compound Mg2Si. Morphology of this compound changed to polyhedral shape with increasing Si addition over 3wt%. The purpose of this paper is to investigate morphological and XRD aspects of casted pure Mg and Mg-XSi-YCa (X – 1.5wt%, 5wt%, 10wt% / Y-0.5wt%, 1wt%, 2wt%) by using optical microscopy, scanning electron microscopy and X-ray diffraction.
Corrosion Behavior in Saline Medium for a Cu-Zn Casting Alloy
Authors: Minciună Mirabela Georgiana , Vizureanu Petrică , Achiţei Dragos , Cimpoeşu Ramona
Published: August 2015

The paper present aspects about the structural modification of CuZn alloy obtained by casting and used to manufacture the housing which works in corrosive liquid mediums. The analyzed alloy has a chemical composition determine by spectral quantitative analysis, with an optic spectrometer type Foundry Masters, using cooper analysis base. The structural modifications, both in cast state, also after corrosion studies, have highlighted by SEM, at 500x and 2000x magnitude. The experiments were made on samples, with specific dimensions for each analysis.
Optical, Structural and Morphological Properties of Ternary Thin Film Blend of P3HT:PCBM:ZnO Nanoparticles
Authors: Bahtiar Ayi , Tusaddiah Siti Halimah , Mustikasari Wendy Paramandhita S. , Safriani Lusi , Kartawidjaja Mariah , Kanazawa Kei , Enokida Ippei , Furukawa Yukio , Watanabe Isao
Published: August 2015

Ternary blend film of conjugated polymer, fullerene and inorganic nanoparticles has intensively studied as active material for high power conversion efficiency (PCE) of hybrid organic-inorganic solar cells. The incorporation of two electron acceptor materials of organic fullerene and inorganic nanoparticles into hybrid with electron donor conjugated polymer is strongly believed can improve the PCE of solar cells by increasing exciton dissociation efficiency due to an increase of interface area between donor and acceptor materials where the positive and negative charges dissociated. We studied optical, structural and morphological properties of ternary thin film containing blend of conjugated polymer poly(3-hexylthiophene (P3HT):fullerene derivative PCBM:Zinc oxide nanoparticles (ZnO-NP) by measuring its optical absorption, crystal structure and film surface morphology. Zinc oxide nanoparticle was prepared by sol-gel method. It has optical absorption below 370 nm and average particle size 40 nm as shown by TEM picture. Ternary thin blend films of P3HT:PCBM:ZnO-NP were prepared by use of spin-coating method. The UV-Vis spectrum of thin film contains absorption peaks originated from contribution of P3HT at wavelengths 520 nm, 550 nm and 600 nm, from contribution of PCBM at 260 nm and 330 nm and from ZnO-NP at wavelengths below 370 nm which confirms that these three materials were well mixed in the films. Its XRD pattern also contains the peaks from each of these three-materials. In this report, we compare surface morphology of thin films of pure P3HT, pure ZnO-NP, blend of P3HT:PCBM, blend of P3HT:ZnO-NP and ternary blend of P3HT:PCBM:ZnO-NP.
Magnetic Composite Fe3O4/CuO/TiO2 Nanoparticles: Preparation, Characterization and Photocatalytic Activity
Authors: Jalaludin Shofianina , Arifin Sarah A. , Saleh Rosari
Published: August 2015

Magnetic composite Fe3O4/TiO2/CuO nanoparticles have been synthesized by sol-gel method at low temperature. The resultant composite nanoparticles coupled with different Cu contained by adjusting the molar ratio of CuO to (Fe3O4/TiO2) from 1:1 – 5:1. The structure, morphology and properties of nanoparticles were characterized using XRD, EDX, FESEM and VSM. The results showed that all composite nanoparticles consist of cubic spinel Fe3O4, anatase TiO2 and monoclinic CuO, have ferromagnetic properties. The photocatalytic performance was evaluated using methylene blue in aqueous solutions under UV and visible light irradiation. Among the composite Fe3O4/TiO2/CuO nanoparticles, the sample with the molar ratio of CuO to (Fe3O4/TiO2) = 5 : 1 exhibited the highest photocatalytic efficiency. Photocatalytic mechanism was investigated by measuring the photocatalytic degradation rate in the presence of scavenger. The results suggested that holes play the most important role in degradation of methylene blue.
μSR Study of Charge Carrier Motion in Active Layer P3HT:ZnO:PCBM Hybrid Solar Cells
Authors: Safriani Lusi , Risdiana  , Bahtiar Ayi , Aprilia Annisa , Kawasaki I. , Watanabe Isao
Published: August 2015

The so-called hybrid (organic-inorganic) solar cell has been developed due to the combining advantage between organic material such as Poly(3-hexylthiohene)/P3HT and inorganic material such as zinc oxide (ZnO). By adding fullerene derivative (6,6-phenyl-C61-butyric acid methyl ester/PCBM) to the hybrid solar cell, the performance of solar cell is predicted to be increased. We have studied the charge carrier motion in blend of P3HT:ZnO:PCBM using LF-μSR with and without light irradiation to clarify the charge carrier motion in bulk ternary system of hybrid material. We found that charge carrier motion in P3HT:ZnO:PCBM changes from intra-chain to inter-chain diffusion. One-dimensional intra-chain diffusion is observed in the sample at low temperature below 15 K, while three-dimensional inter-chain is observed at high temperature above 25 K.
Effect of LiFePO4 Cathode Thickness on Lithium Battery Performance
Authors: Adityarini Ariska Rinda , Ramadhan Eka Yoga , Dyartanti Endah Retno , Purwanto Agus
Published: August 2015

Lithium ion battery is composed of three main parts, i.e. cathode, anode and electrolyte. In this work, we investigated the effect of LiFePO4 cathode composite’s thickness on performances of lithium battery. LiFePO4 cathode was prepared in a slurry that consisted of lithium iron phosphate (LiFePO4) powder as active material, acetylene black as conductive additive, polyvinylidene fluoride (PVDF) as binder, and N-methyl-2-pyrrolidone (NMP) as solvent. The slurry was then deposited on the aluminum substrate using doctor blade method in different thickness. The cathode layers were deposited with the thickness of 150, 200, 250 & 300 μm. The structure characterization of the material was analyzed by XRD, while the material’s morphology was analyzed by Scanning Electron Microscope (SEM). Performances of lithium ion battery with LiFePO4 cathode were evaluated using charge-discharge cycle test. It is found that battery made of cathode layer with 250 μm thickness shows the best performances.
Microscopic Characterization of Cellulose Nanocrystals Isolated from Sisal Fibers
Authors: Sosiati Harini , Muhaimin Mu'minul , Purwanto  , Wijayanti Dwi Astuti , Harsojo  , Soekrisno  , Triyana Kuwat
Published: August 2015

Isolation of cellulose nanocrystals (CNCs) was carried out by unrepeated or repeated alkalization and bleaching followed by sulfuric acid hydrolysis and air cooling (unrepeated) or ice cooling (repeated). The influence of unrepeated and repeated alkalization and bleaching, and cooling rate (cooling medium) after hydrolysis on the morphology and crystallinity of the isolated micro- and nano-celluloses were characterized. Scanning electron microscopy (SEM) showed that repeated alkalization and bleaching led to a higher degree of fibrillated microcellulose (~10 mm) with higher surface roughness than unrepeated alkalization and bleaching. Transmission electron microscopy (TEM) revealed that air and ice cooling after acid hydrolysis producing different CNCs morphologies; heterogeneous CNCs nanowhisker and nano-spherical (~50 nm), and homogenous CNCs nanowhiskers (~50 nm width and ~500 nm length), respectively. The homogeneous nano whisker was related to single phase monoclinic b-cellulose. Residual lignin agglutinating between the nanoparticles was observed in TEM image as well as in Fourier transform infrared (FTIR) spectra. The existence of residual lignin after hydrolysis is comparable in crystalinity (crystallinity index,Ic: ~91%) with that of isolated CNCs, as confirmed by x-ray diffraction (XRD) analysis.
Simulation Analysis of Damage Mechanism on Ferritic Material SA-213 T22 Type Using Finite Element Method Program
Authors: Mulyana Cukup , Nurhilal Otong , Syah Adhitya Rusel , Suhendi Nendi
Published: August 2015

Material with good mechanical resistance in the high temperature operation is needed in the power generation industry. Due to the influence of stress, high temperatures and long operation of time, unpredictable failure often occurs resulting plant stopped working. The cause of failure, associated with some changes in mechanical properties of the material can be represented by microstructural conditions. Ferritic material SA-213 T22 is widely used in power plants. To get more information of those mechanical properties, the study of damage mechanisms has been conducted by analysis simulation. The Benefits of this study is to get proper operating condition to avoid unpredictable failures. Using finite element method, it is found that in constant temperature 580 °C with the load rate of 23.03MPa per second the strain is 55.25%. When the load rate is decreased to 3.84MPa per second the strain is 63.57%. In the constant temperature 300 °C with load rate 11,52MPa per second the strain is 27.55%. When the temperature increased to 560 °C the strain is 32.02%. In the constant temperature, the decreased of load rate give impact the increased of ductility. Otherwise in the constant load rate, the increased of temperature give impact only small amount to increase the ductility. To prevent the unpredictable failure the sudden increase of load rate should be avoided.
Deposition of Ag 2~6 mol%-Doped ZnO Photocatalyst Thin Films by Thermal Spray Coating Method for E.coli Bacteria Degradation
Authors: Sutanto Heri , Nurhasanah Iis , Hidayanto Eko
Published: August 2015

ZnO doped with 2~6 mol% Silver (Ag) photocatalyst thin films has been deposited on glass substrate by thermal spray coating with temperature deposition of 250°C. A gel of ZnO:Ag precursor has been synthesized by sol-gel route from aqueous/alcoholic solution of zinc acetate dehydrate and silver nitrate mixture at room temperature. The morphology of ZnO:Ag films were investigated scanning electron microscopy (SEM). 3D SEM images of ZnO:Ag thin films show the rough morphology with roughness mean square (rms) of 150 to 195 nm. The grain size of ZnO:Ag films were found in the range 76,5 to 304,8 nm. The photoactivity examination of ZnO:Ag photocatalyst films show the E. Coli bacteria degraded up to 99.99% under sunlight irradiation for 4 hours.
Preparation and Characterization of Ni/Zr-Saponite as Catalyst in Catalytic Hydrogen Transfer Reaction of Isopulegol
Authors: Fatimah Is , Rubiyanto Dwiarso , Huda Thorikul
Published: August 2015

World demand on menthol is so high and it is also a chalenge for organic synthetic chemist to develop new method of synthesis and conversion from another sources. Tandem cyclization-hydrogenation reaction towards citronellal is one important mechanism recently. Within the mechanism, hydrogenation of isopulegol is rate determining step. Considering green chemistry principles, this research deals with the use of heterogeneous catalyst in hydrogenation, Nickel (Ni) and also the use of microwave assisted organic synthesis method. An effort to improve activity and reusability of nickel in the reaction was conducted by dispersion in pillared clay materials, Ni-saponite.Nickel immobilized zirconia pillared saponite (Ni/Zr-Saponite) was prepared using pillarization-impregnation method. The composite, Zr-Saponite and Saponite were characterised by Scanning Electron Microscopy-energy dispersive x-ray (SEM-EDX), x-ray diffraction (XRD), surface acidity and surface area parameter based on nitrogen adsorption-desorption method. Catalytic hydrogen transfer of isopulegol hydrogenation was used as reaction model to show the comparison of catalytic activity.The XRD and SEM-EDX results of the composite indicate that zirconia was successfully distributed as pillar and nickel was dispersed within the pillared material. Both modifications increased the specific surface area, pore volume and surface acidity as a result of pillar formation and homogeneous distribution of the particles. Compared to raw saponite and Zr-Saponite, the composite exhibits significant improvement on total conversion of isopulegol. The presence of nickel affect the hydrogenation mechanism as showed by the product of menthol by catalytic hydrogen transfer.
Failure Analysis Study of Dissimilar Metal Weld SA-213 T22 and SA-213 TP304H at Boiler Tube Steam Power Generation
Authors: Mulyana Cukup , Saad Aswad Hi , Kartawidjaja Mariah , Henboral Agtri
Published: August 2015

Critical component of boiler that frequently experiencing failure is on the junction of boiler tube consist of two different materials. This failure mechanism would lead to tube rupture and would be followed by power plant shutdown. Failure analysis has been conducted on dissimilar metal weld (DMW) of Ferritic SA-213 T22 welded with Austenitic SA-213 TP 304H. This tube is used in Suralaya Steam Power Plant. Operating temperature and pressure of the steam inside the tube in normal condition are respectively 196.8kg/cm2 and 540 °C.In order to understand the real cause of failure several tests are ran, which are chemical composition test, micro vickers, and metallographic test on based metal, heat effective zone, and filler area. The tests are conducted in a layered manner to clearly understand the cause of the failure. Causes of the failure are due to the contribution of carbon diffusion and disparity of expansion coefficient of two materials.
Photocatalytic Activity of Zeolite Supported Transition Metal-(Co2+ and Cr2+) Doped ZnO: Comparative Study
Authors: Noorhidayati Annisa , Rahmawati Mia Putri , Djaja Nadia Febiana , Saleh Rosari
Published: August 2015

Transition metal ions (Co and Cr) doped ZnO nanoparticles supported on natural zeolite were synthesized using co-precipitation method. The synthesized samples were characterized by means of X-ray diffraction, energy dispersive X-ray, Fourier-transform infrared absorption, and UV-visible diffuse reflectance spectroscopy. The samples were further used as photocatalyst for degradation of methyl orange and methylene blue in aqueous solutions under UV light irradiation. The results showed that zeolite supported Cr-doped ZnO nanoparticles is more efficient compared with zeolite supported Co-doped ZnO nanoparticles. It is also revealed that zeolite supported samples possessed higher photocatalytic efficiency compared to bare samples.
Growth and UV Absorption of 5 mol% Zn-Doped CeO2 Nanoparticle Synthesized with a Simple Precipitation Process
Authors: Nurhasanah Iis , Efendi Aula Fitra , Sutanto Heri , Priyono
Published: August 2015

Nanoparticles of the 5 mol% Zn-doped CeO2 have been synthesized by simple precipitation process from aqueous/alcoholic solution of cerium nitrate and zinc nitrate mixture at room temperature. Dried precipitates were calcined at 300-700°C for 2 hours. The structure and growth of 5 mol% Zn-doped CeO2 was investigated using X-ray diffraction measurement. All the peaks in X-ray diffraction patterns are identified and indexed as single crystalline phase of cubic fluorite CeO2. The enhancement in calcination temperature increases the crystallite size from 5.51 to 15,56 nm and improves crystallinity of that nanoparticle. The low activation energy for crystallite growth of the 5 mol% Zn-doped CeO2 is found to be 10.85 kJ/mol. The UV-Vis spectrophotometer measurement shows the UV absorption property of the 5 mol% Zn-doped CeO2 enhanced with the increasing calcination temperature. The 5 mol% Zn-doped CeO2 nanoparticle calcined at temperature 600°C is found to be more effective as UV-blocker.
Synthesis, Characterization and Photocatalytic Performance of ZnO/TiO2 and ZnO/TiO2/CuO Nanocomposite
Authors: Albert Alfred , Saleh Rosari
Published: August 2015

In the present study, an attempt was made to synthesize ZnO/TiO2 and ZnO/TiO2/CuO nanocomposites as photocatalyst for degradation of organic pollutant (methylene blue) in aqueous solution under UV and visible light irradiation. Characterization using X-ray diffraction, energy dispersive X-ray spectroscopy, field emission scanning microscope electron, diffuse reflectance spectroscopy analysis confirmed that all three components phase are present in the photocatalyst. The photodegradation of organic pollutant showed that with the incorporation of CuO content in ZnO/TiO2 nanocomposites increasing the photocatalytic performance in ultraviolet as well as visible region.
Preparation and Characterization of Magnetic Carbonate Apatite/Chitosan/Alginate Composite Scaffold
Authors: Indrani Decky Jusiana , Purwasasmita Bambang Sunendar , Adi Wisnu Ari , Simanjuntak Jojor
Published: August 2015

Treatment for bone cancer has begun to be experimented with ferrimagnetic for magnetic induction hyperthermia. On the other hand, composites of bioceramics and biopolymer have been studied for scaffold as these materials resemble the structure of bone. The current study investigated the magnetization of calcium aluminum ferrite magnetic (CaAl4Fe8O19) incorporated in carbonate apatite, alginate and chitosan, that serves as a scaffold. CaAl4Fe8O19 powder were synthesized using calcium nitrate, aluminium nitrate and ferrous chloride using the sol-gel method. Combining the carbonate apatite/chitosan/alginate compoiste and CaAl4Fe8O19using the freeze-dry method has produced carbonate apatite/alginate/chitosan/CaAl4Fe8O19 composite scaffolds. The CaAl4Fe8O19powder and the scaffolds were observed using SEM (scanning electrone microscope) and their magnetization were measured using VSM (vibrating sample magnetometer). It was shown that the scaffold is a composite structure of CaAl4Fe8O19 particles, having diameter ranging from 0.5 to 2 µm, embedded in the pore walls of the carbonate apatite/alginate/chitosan matrix. The saturation magnetization Ms and remanence magnetization Mr of the CaAl4Fe8O19particles were 20 and 2.0 emu/g, whereas, those of the magnetic scaffold were 4.3 and 2.0 emu/gr. The addition of the carbonate apatite/alginate/chitosan composite into CaAl4Fe8O19 decreased the fraction and/or magnetic of the CaAl4Fe8O19 particles.
Segregation Characteristics of Rheo-High Pressure Die Cast Al-Alloy 2139 Plates
Authors: Taute Carlien , Möller Heinrich
Published: August 2015

Al-Cu-Mg-Ag alloy 2139 is a wrought alloy that is heat-treatable and used in aerospace constructions. This is mainly due to the addition of silver in the alloy. Hot-tearing is a problem for casting wrought alloys with conventional liquid casting techniques. The risk is reduced by using rheo-high pressure die casting (R-HPDC) to allow the alloy to be used for near-net shape forming of components. This study investigates the segregation characteristics of R-HPDC alloy 2139. The effects of segregation on the age-hardening response as well as the tensile properties are studied. The chemical composition differences across the casting were found to aid in correlation of results. It is found that segregation occurs in three dimensions, namely from the surface to the centre of the casting, as well as across the width and length of the casting.
Deformation and Densification Study of Titanium Powder Compact during Powder Forging Using Gurson and Gurson-Tvergaard Criterion
Authors: Velluvakkandi Navaneeth , Gabbitas Brian , Raynova Stella
Published: August 2015

Powder forging is a recently developed manufacturing process to produce low cost titanium components with superior properties. Conventional P/M techniques such as compaction and sintering have proved inadequate for producing dense and high performance titanium components, while forging still remains a primary process in the manufacturing of high performance titanium components. A numerical simulation of powder compact forging would increase our understanding of the flow behaviour of material in the forging die. In this study, a 2D FEM coupled thermal displacement model was used for analysing deformation and densification of a powder compact during upset forging. Simulations were performed using the Gurson and Gurson-Tvergaard material models, to predict the densification behaviour at three different forging temperatures and the results were compared with radio-graphically obtained density results. The influence of parameters such as friction, heat transfer and material flow is discussed with respect to relative density.
Contribution of Hydrogen Promoted Aluminium Partitioning to Tempered ά Martensite Embrittlement in Ti-6Al-4V
Authors: Vilane V.N. , Knutsen R.D. , Westraadt J.E.
Published: August 2015

A thermohydrogen process promoting metastable phase decomposition (THP-MD) treatment was performed on wrought Ti-6Al-4V to determine the effects of microstructure evolution on tensile ductility. Tensile ductility was affected by the nature of phase and morphology evolution in which dissolved hydrogen played a key role. Hydrogen reduced the beta transus and stabilised more beta phase at aging/tempering temperature. A reduced beta transus in a similar heat treatment resulted in a bimodal morphology (in non-hydrogenated samples) or a fully acicular morphology (in hydrogenated samples). It also reduced the volume fraction of alpha at aging/tempering temperature which resulted in the extensive enrichment of reduced alpha with aluminium (Al) during tempering. The increased Al content in the reduced alpha promoted ordering of the HCP lattice to the brittle titanium aluminide (Ti3Al) phase. In addition to Ti3Al embrittlement, the acicular morphology of Ti-6Al-4V tempered hexagonal martensite (ά) offers limited resistance to crack propagation. The highest degree of embrittlement was observed in prior hydrogenated samples because of the combined effect of the acicular morphology and Ti3Al embrittlement.
Effect of Ageing Treatment on the Microstructure and Hardness of the Ti6Al4V Alloy
Authors: Masete Stephen , Mutombo Kalenda , Siyasiya Charles , Stumpf Waldo
Published: August 2015

The effects of ageing temperature, time and cooling medium on the microstructure and hardness of a solution treated Ti6Al4V alloy were investigated. The furnace cooling after ageing for 0.5 hours gave a homogenous structure with higher hardness values than the solution treated and water quenched Ti6Al4V alloy. Increasing the ageing time to 2 hours reduced the alloy hardness. Ageing at temperatures between 500 and 700°C, followed by furnace cooling, led to homogenously distributed α- and β-phases within a fully martensitic matrix leading to improved hardness. A heterogeneous structure with a high variation in microhardness was revealed when ageing at 800 and 900°C.
Optimization of the Solution Heat Treatment of Rheo-High Pressure Die Cast Al-Cu-Mg-Ag 2139 Alloy
Authors: Daswa Pfarelo , Möller Heinrich , Govender Gonasagren
Published: August 2015

This paper investigates the optimization of the solution heat treatment parameters of the rheo-high pressure die cast (R-HPDC) 2139 aluminium alloy. Differential Scanning Calorimetry (DSC) and optical microscopy were used to investigate the incidence of incipient melting and therefore determine suitable solution heat treatment temperatures. A three-step solution heat treatment where the alloy was heat treated from 400°C to 513°C using controlled heating conditions and held at 513°C for 2 hours and finally heated up from 513°C to 525°C and held there for 16 hours was done. R-HPDC is known to produce surface liquid segregation and when processing the alloys these areas are most prone to incipient melting. The applicability of a single (525°C for 16h) and three-step solution heat treatments on the R-HPDC 2139 aluminium alloy was also investigated. A single-step solution heat treatment results in incipient melting, whereas this is mostly eliminated using the three-step solution heat treatment. However, a high volume fraction of undissolved phases remain in the liquid segregated areas, even after the three-step solution heat treatment.
The Effect of Natural Pre-Ageing on the Mechanical Properties of Rheo-High Pressure Die Cast Aluminium Alloy 2139
Authors: Chauke Levy , Daswa Pfarelo , Möller Heinrich , Govender Gonasagren
Published: August 2015

Near-net shape casting of wrought aluminium alloys has proven to be difficult due to hot tearing. The Council for Scientific and Industrial Research (CSIR) has successfully processed wrought aluminium alloy 2139 into plate castings using the Rheo-high pressure die casting process (R-HPDC). Alloy 2139 is a Ag-containing aluminium alloy from the Al-Cu-Mg 2xxx series family. The addition of Ag enhances the age hardening response through the formation of co-clusters that act as precursors to the formation of plate-like Ω precipitates. These co-clusters typically form during natural ageing and 12-24 h of natural pre-ageing is normally specified before artificial ageing in Ag-containing Al-Cu-Mg alloys. The T6 hardness and tensile properties of R-HPDC 2139 alloy were investigated with and without natural pre-ageing. It is shown that there is no significant difference in both peak hardness and tensile properties in R-HPDC alloy 2139 with and without natural pre-ageing. The possible precipitation phenomena in both cases are discussed.
Effect of Zn and Zr Concentration and Extrusion Conditions on the Mechanical Properties of Lean ZK Alloys
Authors: Ross N.G. , Elrefaey A. , Kretz Richard , Kilian Helmut
Published: August 2015

Compared to Al alloys Mg alloys are generally slower to extrude and this makes them expensive to process. However, making alloys easier to extrude usually equates to reduced extrudate strength. The effects of extrusion parameter, billet heat treatments and alloying element concentration on extrudability and extrudate mechanical properties are compared using four lean ZK alloys. By weight percent there was a greater increase in peak extrusion pressure and extrudate yield strength from increasing Zr than from Zn. Homogenising the extrusion billets had no effect on the lean alloys and only a minor effect on the richer alloys. Alloying element concentration has the most effect on alloy mechanical properties, while changing the extrusion speed and temperature has little influence on the extrudate mechanical properties.
Development of Biodegradable Coating for Controlled Dissolution of a Magnesium Alloy as an Implant
Authors: Swati Gaur , Khanna Anand Sawroop , Singh Raman R.K.
Published: August 2015

In the present study, combinations of a Phosphonato silane DEPETES with MTEOS silane, in various ratios were applied on Mg6ZnCa alloy. The coating morphology was characterized using scanning electron microscopy (SEM) and hydrogen evolution and pH variation of the samples were studied. The results showed that the sol-gel coatings reduced the hydrogen evolution rate of the magnesium alloy inm-simulated body fluid (m-SBF) solution. Moreover, biological response like cell attachment on the coated sample was found to be enhanced considerably compared to the bare alloy
Laser Weldability of Different Al-Zn Alloys and its Improvement
Authors: Enz Josephin , Riekehr Stefan , Ventzke Volker , Kashaev Nikolai
Published: August 2015

Weld defects - such as porosity and hot cracking - occur especially during the laser beam welding of high-alloyed Al-Zn alloys. This significantly limits the application range of these promising high-strength alloys. In the present study the laser weldability of different Al-Zn alloys was investigated regarding the used welding parameters and the chemical composition of the alloys. In addition, the novel approach of the Helmholtz-Zentrum Geesthacht for overcoming the weldability problems was applied to the different Al-Zn alloys in order to assess its capability. It was shown that the laser weldability of Al-Zn alloys deteriorates with an increasing amount of Zn, Mg and Cu. The variation of laser beam welding parameters did not lead to any improvement of weldability. Only the use of the new approach resulted in promising welding results even for the high-alloyed Al-Zn alloys.
On the Development of Mg Sheets with Improved Formability by Applying Additional Shear Strain during Processing
Authors: Letzig Dietmar , Suh Joungsik , Bohlen Jan , Yi S. , Kurz Gerrit , Golle Rolland , Volk Wolfram , Victoria-Hernandez Jose
Published: August 2015

Reducing vehicle weight and emissions by lightweight design is a major goal of the automotive industry. Magnesium as the lightest structural metal offers a significant weight saving potential compared to steel and aluminum. However, the poor formability of magnesium semi-finished products (e.g. sheets) has hindered the massive application of this metal. This poor formability arises due to the formation of strong textures. Typically the basal planes of the HCP-structure align parallel to the sheet plane. Such preferred orientation of the basal planes limits the ability of basal  slip to accommodate plastic strain in the sheet plane and is thus unfavourable for ductility and formability of the sheets, especially at room temperature. A combination of new technologies could help to alleviate the strong textures formed in Mg sheets. In this regard the utilization of twin-roll casting (TRC) in combination with processing techniques which apply additional shear strain such as differential speed rolling (DSR) and/or equal channel angular pressing (ECAP) could refine the microstructure and modify the resulting deformation texture. In this study an AZ31 strip (3Al-1Zn-Mg Bal. wt.%) produced by TRC was hot rolled at 400 °C using a rolling speed of 10 m/min. A speed ratio of 10% between rolls was used. Rolled samples with dimensions of 200 x 200 x 1.8 mm receive a single pass of ECAP at 200 °C. After processing the microstructure of the samples were analyzed by means of optical microscopy, electron backscatter diffraction and X-ray diffraction. The results showed that the microstructure can be refined and the texture altered in comparison to conventionally rolled AZ31 sheets. The samples processed by ECAP show an increase in formability up to 50% higher than conventionally rolled sheets. This demonstrates the potential of using shear deformation for processing Mg sheets.