bluuebunny/crossref_metadata_2025 huggingface dataset:
Heating Time Dependent Pore Size of Porous Composite from Waste Glass
Authors: Sulhadi Sulhadi , Susanto Susanto , Wiguna Pradita Ajeng , Savitri Meiriani Ismu , Nur Said Muh. Afis , Prasetya Aji Mahardika
Published: August 2015

Porous composites from waste glass were synthesized by simple heating process. The ability in the control of pore size was controlled by adjusting the time of melting point. In this study, the time of melting process was used a pore-forming agent in composite from waste glass. The composites from waste glass had been synthesized at 750οC with controllable of time 1, 2, and 3 hours. The characterization was showed by BET method. The composites from waste glass have decreased value of surface area. The composites with controllable of time 1, 2, and 3 hours, each other have 0.820 m2/g, 0.734 m2/g, and 0.445 m2/g. Porous composites from waste glass could be used in various applications, such as water filter.
Identification of Carbon Dots in Waste Cooking Oil
Authors: Prasetya Aji Mahardika , Wiguna Pradita Ajeng , Susanto Susanto , Wicaksono Rahmawan , Sulhadi Sulhadi
Published: August 2015

We found carbon dots (C-Dots) in waste cooking oil. The C-Dots were formed as result of heating process. The Heating process caused carbon chains on waste oil were cut off and suffered rearrangements (polymerization) of carbon chains that accompanied with the process of carbonization. Luminescence C-Dots were observed while C-Dots on waste oil was irradiated by UV Light and the emissions were radiated in the visible light area which looks yellow-greenish color. The Heating process with different temperatures caused changes in the structure and the band gap energy. Structural changes were observed from the FTIR spectrum where the intensity of functional groups C ⎯ OH, C ⎯ H and C = O on a degraded waste oil. While the band gap energy of C-Dots displaces due to hydrothermal processes with different heating temperature. The Band gap energy shifted from 0.5 eV to 2 eV at 300οC of heating temperature. This study shows that we found an alternative raw material for luminescence materials.
The Effect of a Hydrophobic Coating Material on Friction in a Micro-Slider Bearing: A Numerical Analysis
Authors: Tauviqirrahman Mohammad , Muchammad Muchammad , Ismail Rifky , Jamari J. , Schipper Dirk Jan
Published: August 2015

The use of conventional lubricant such as hexadecane and toluene in micro-bearings has shown poor performance due to their hydrophilicity. High friction between the lubricated surfaces could lead to the occurrence of stiction which limits the functionality of a micro-bearing. In order to assess this strategy, a lubrication model of a micro-slider bearing with modified surface was used to simulate the technology. Friction, hydrophobic zone and hydrophobicity coefficient were evaluated based on the modified Reynolds equation. Results showed that in general the application of a hydrophobic coating has a significant improvement in reducing friction. Further, particular care must be taken in choosing the hydrophobic coating zone; an inappropriate choice of this zone will lead to a deterioration of the friction. This finding may have useful implications to accelerate the development of micro-bearings.
Theoretical Studies of the Effects of Magnetic Field on the Phase Transition of Swollen Liquid Crystal Elastomers
Authors: Warsono Warsono , Yusuf Y. , Nurwantoro Pekik , Abraha Kamsul
Published: August 2015

The effect of magnetic fields on the swelling of liquid crystal elastomers (LCE) dissolved in liquid crystal (LC) solvent have been studied. The Flory-Huggins model used to calculate the free energy of an isotropic mixing and the Maier-Saupe model used to calculate the free energy of a nematic mixing. Numerical integration method used to calculate the orientational order parameter and the total free energy of system (consists of : nematic free energy, elastic free energy, isotropic mixing free energy and magnetic free energy) and the calculation results graphed as a function of temperatures for various magnetic fields and as function of magnetic fields for various of temperatures. We find that the magnetic field shifts the transition points towards higher temperatures, increases the energy transition, and induces an isotropic phase to paranematic phase.
Estimation of Van der Waals Interaction Using FTIR Spectroscopy
Authors: Masturi Masturi , Sunarno Sunarno
Published: August 2015

Van der Waals (vdW) interaction is one of the important properties in the composite. The usual measurement used to investigate the vdW interaction between filler and polymeric binder is FTIR spectroscopy where the result obtained is the band shift appearance, however, it has not been used yet to estimate the vdW magnitude. Using the Lennard-Jones potential, we developed a new analysis method to obtain approximately its magnitude and further the distance between filler atoms and polymeric group. We used our model proposed to several data reported by some authors, and interestingly we also found an appearance of anharmonic vibration of the atoms.
Characterization of Main-Chain Liquid Crystal Elastomers by Using Differential Scanning Calorimetry (DSC) Method
Authors: Supardi Supardi , Yusuf Y. , Harsoyo Harsoyo
Published: August 2015

We performed an experiment to characterize the four samples of main chain liquid crystal elastomers (MCLCEs) by using differential scanning calorimetry (DSC) method. Basic principle of this method is that difference in the amount of heat required to increase the temperature of the sample and reference is measured as a function of temperature. The temperature between the sample and reference is maintained nearly the same throughout the experiment. There were four samples with different concentrations of crosslinker we have taken, namely 8%, 12%, 14%, and 16%. The results showed that the phase transition from nematic to isotropic obtained by this method had correlation with their thermo-mechanical effects.
The Effect of KOH Activation in Synthesis and Characterization of Zeolitic Imidazolate Frameworks-8 (ZIF-8) Templated Mesoporous Carbon
Authors: Alifah Miratul , Devianti Vika Ayu , Mukminin Amirul , Rachmawati Yulia , Ainul Fahmi Muhammad , Ediati Ratna
Published: August 2015

ZIF - 8 material has been successfully synthesized through a reaction between zinc nitrate hexahydrate with 2 - metilimidazol in the dimethylformamide solvent in solvotermal condition. Synthesis process is carried out at 120oC for 24 hours . The results show that the characterization by XRD diffractogram synthesized ZIF - 8 has a characteristic peak at 2θ = 7.4o; 12.7o; 16.5o and 18.0o corresponding to the characteristic peaks of ZIF - 8 standard . The results of ZIF - 8 templated carbon show the XRD pattern of amorphous carbon material, while the carbon activated KOH show peak K2CO3 at 2θ = 31.6o. FTIR spectra of synthesized ZIF - 8 has a absorption peak at 420; 760 ; 990 ; 1147 and 1585 cm-1 which is the characteristic absorption peak of ZIF-8 solids. Then ZIF - 8 characteristic peaks disappear after activated with KOH. Morphology of the ZIF-8 has plumage regular rectangular in shape , and morphology of the resulting carbon particles are also the same rectangular shape with ZIF-8 template.
The Effect of Low Vacuum Curing to Physical and Magnetic Properties of Bonded Magnet Pr-Fe-B
Authors: Kurniawan Candra , Hutahaean Ruth Mentari , Muljadi Muljadi
Published: August 2015

In this paper, the physical and magnetic properties of isotropic bonded magnet Pr-Fe-B manufactured at atmospheric and low vacuum condition were discussed. The commercials Pr-Fe-B melt spun ribbon which mixed with epoxy resin binder was used as starting materials. The compaction method was using hydraulic press of 3 grams sample (ϕ9 mm) with force of 3 tons. The atmospheric and low vacuum (P ~ 10 mbar) environment during curing process were sets with temperature varied from 100 °C to 200 °C. The curing time (t) variations of 30 minutes to 4 hours were also done in the selected temperature to understand the short term aging effect. The optimum curing time was generated in 4 hours which produced at the low vacuum curing that increased the sample density and magnetic flux with the value of 5.846 g/cm3 and 2.51 kG, respectively. Generally it can be concluded that the process of low vacuum curing give a positive trends for manufacturing the bonded magnet Pr-Fe-B. The analysis of microstructure for mentioned parameters using SEM were also discussed.
The Effect of Powder Particle Size on the Structural and Magnetic Properties of Bonded NdFeB Magnet
Authors: Aryanto Didik , Ray Zailani , Sudiro Toto , Wismogroho Agus Sukarto , Sudrajat Nanang
Published: August 2015

Commercially, NdFeB powder (type MQP-B+) with difference in particle sizes were used in this study. The powders were isotropically compressed and heat cured at 150°C for 30 minute. The samples were then magnetized and characterized by impulse magnetizer K series and permagraph MAGNET-PHYSIK Dr. Steingroever GmbH, respectively. According to the results of SEM characterization, compacted powder showed a homogeneous plate distribution. The surface morphology also indicated the presence of pores in the bonded NdFeB magnet. X-ray diffraction analysis from all samples revealed that the diffraction peaks were detected as tetragonal Nd2Fe14B-phase. There was no significant different in magnetic properties of bonded magnets with different in particle size. The optimum Br, Hcb, and (BH)max were achieved at particle size range of 150-297 mm.
Poly(aniline-co-m-aminobenzoic acid): A Novel Ester Vapor Sensor and its Thin Film Deposition on Silane Functionalized SAM Glass Surface
Authors: Singh Jyoti , Banerjee Rintu , Adhikari Basudam
Published: August 2015

In recent years, a great deal of attention has been paid on coating the surface of glass and related inorganic substrate with a layer of polymers having special properties to prepare various functional materials. On a smooth surface of glass, the adhesion of a conductive polymer is generally poor. The increase of the surface adhesion was achieved through a chemical pre-treatment. One of the method is to generate a self-assembly monolayer or patterned SAM monolayer to increase the surface adhesion property of glass surface towards polymer solutions [1,2]. Self-assembled monolayers (SAMs) are monomolecular layers which are spontaneously formed upon immersing a solid substrate into a solution containing functional molecules. SAMs can be prepared using different types of molecules and different substrates. Aminosilanes such as (3-Aminopropyl)-triethoxysilane (APTES) are attractive for such applications [3]. Particularly, aminosilanes have the advantage of catalytic activity by the amine group that facilitates formation of siloxane bonds with surface silanols. In present study, a 3-step procedure for the introduction of APTES on glass pieces is described. After chemisorptions of APTES, poly (aniline-co-m-aminobenzoic acid) synthesised by inverse emulsion polymersation route was coated on to the functionalised glass surface in the form of a solution prepared in DMSO. The modified glass was characterized mainly by IR spectroscopy and contact angle measurement. The coated glass was used for ester sensing.
Preparation, Characterization and Catalytic Activity of Sulfated Zirconia by Varied Sol-Gel Method
Authors: Fatimah Is , Zuhrufa Zulfa
Published: August 2015

The sulfated zirconia catalysts were was prepared by sol–gel processes consist of varied templating method. Both preparations consist of sol-gel synthesis of zirconium dioxide followed by sulfatation process by using NH4SO4 solid reaction method. Two different templating agent; urea and cetyltrimetyl ammonium bromide was used in sol-gel processes. The prepared material was characterized using scanning electron microscope (SEM), x-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) measurements. From the XRD measurement it can be concluded that both materials consist of ZrO2 in combined phases while from BET surface area analysis it can be noted that material prepared by urea template has higher specific surface area compared to that use CTAB template. Both materials exhibit the activity as acid catalyst in microwave assisted conversion of citronellal. It is also confirmed that the higher the surface area the higher total conversion of citronellal obtained. Study on the correlation between physicochemical properties of materials with the catalytic activity was discussed in this paper.
Review of Geopolymer Materials for Thermal Insulating Applications
Authors: Azimi Emy Aizat , Al Bakri A.M. Mustafa , Liew Yun Ming , Heah Cheng Yong , Hussin Kamarudin , Aziz Ikmal Hakem
Published: August 2015

Geopolymer is an environmentally cementitious binder that does not require the existence of ordinary Portland cement (OPC). Geopolymer has many excellent advantages, including high early strength, low shrinkage, good thermal resistance and good chemical resistance. Based on previous research, geopolymer offered good resistance to corrosion, abrasion and heat. Fly ash, metakaolin, kaolin, and slag are regularly used raw materials for the preparation of geopolymer composites. Geopolymer composites also offer a potential environmental friendly product by reduce the carbon dioxide (CO2) emissions. This geopolymer material also offers an innovative and sustainable solution for maintaining infrastructure and also provides superior thermal, chemical and mechanical performance. This paper summarizes some research outcomes on alkali-activated binders along with the potential of geopolymer composites for thermal insulating applications.
Measurement of Glucose in Blood Using a Simple Non Invasive Method
Authors: Abidin Muhammad Sainal , Rajak Abdul , Salam Rahmat Awaludin , Munir Muhammad Miftahul , Khairurrijal
Published: August 2015

The amount of glucose in blood of human beings should be controlled. The excess or deficiency in glucose of human blood can cause a variety of diseases such as diabetes, heart disease, cholesterol and blindness. We report the design and development of a simple spectrometer as a non-invasive method to determine glucose in urine. Note that glucose in urine, which is caused by exceeding glucose level from the threshold in the renal system, is correlated with that in blood since glucose is a part of acid hydrate in the digestive tract and is absorbed by the intestine in the blood circulation. Urine containing glucose is reacted with a benedict solution that in turn affects the turbidity of urine according to the glucose concentration in the urine. Urines with various turbidities were then placed in transparent containers sitting between a light emitting diode (LED) as a light source and a photodiode as a detector of the simple spectrometer. As the concentration of glucose in the mixture solution became higher, the mixture solution developed more turbid and the output voltage of the photodiode would then be smaller. Moreover, the color of LED affects the magnitude of light intensity that can be transmitted by the sample.
AC-MnO2-CNT Composites for Electrodes of Electrochemical Supercapacitors
Authors: Subagio Agus , Priyono  , Pardoyo  , Aswardi  , Yudianti R. , Subhan A. , Taer E.
Published: August 2015

Electrodes for electrochemical supercapacitors were fabricated by doctor blade method of composite of activated carbon (AC), MnO2 and carbon nanotubes (CNTs). The AC-MnO2-CNTs composites were synthesized by solution processing method with pH variation of 3, 7 and 11. The composites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and impedance spectroscopy. The XRD pattern shown the crystalline structure and the SEM image observed that the distribution of CNTs was homogeneous between carbon particles. The electrodes were fabricated for supercapacitor cells with 316L stainless steel as current collector and 1 M Na2SO4 as electrolyte. An electrochemical characterization was performed by using an electrochemical impedance spectroscopy (EIS) method using a LCR Hi-Tester HIOKI 3522 instrument and the results showed an increase in the value of specific capacitance at the AC-MnO2-CNT on the acid reaction condition.
The Effect of Sintering and Soaking Temperature on the Dye-Sensitized Solar Cell Performance
Authors: Paramitha Tika , Paramitha Tifa , Purwanto Agus
Published: August 2015

Dye-sensitized solar cell (DSSC) is a photoelectrochemical solar cell that is able to convert solar energy into electrical energy. Sintering of TiO2film and soaking process of TiO2film in the dye solution have significant effect on the DSSC performance. The TiO2film was sintered at varied temperature from 200 °C to 500 °C for 60 minutes. From the efficiency test, it is found that the optimum performance of DSSC was produced when the TiO2film was sintered at 450 °C. In addition, the dye soaking temperature was evaluated from the temperature 40 °C to 50 °C for 6 hours. The optimum soaking temperature was 50 °C of DSSC with maximum efficiency at 2,621 %.
Effects of Gamma Radiation on Electrical Conductivity of PVA-CH Composites
Authors: Susilawati  , Doyan Aris
Published: August 2015

Keywords: Gamma radiation, electrical conductivity, PVA-CH compositesAbstract.The effects of radiation on polymer composite PVA-based organic blends containing chlorine have been studied for their potential applications in electrochemical devices. The polymer composite PVA-Chloral Hydrate (CH) were blended separately with 23, 34, 45 and 57% CH. The composite films were prepared by solvent-casting method and each film has been irradiated with g-rays at different doses up to 12 kGy. The electrical properties have been studied using an impedance analyzer of LCR meter in the frequency range from 20 Hz to 1 MHz. The conductivity-dose relation study revealed that increase in conductivity of the irradiated PVA-CH blends with increasing dose up to 12 kGy. The increase in the conductivity with dose is attributed to the increase of ionic carriers in the composites induced by radiation scission of CH molecules and also due to hydrolysis of water.
Synthesis and Characterization of Carbon-Coated LiFePO4 with Various Carbon Sources as Cathode Material for Lithium Ion Batteries through a Solid-State Process
Authors: Triwibowo Joko , Alamsyah Irvan , Setiawan Jan
Published: August 2015

Synthesis of carbon-coated LiFePO4 as cathode material is performed through a solid-state process. Materials in the form of a powder comprising LiOH.H2O and Fe2O3 and H3PO4 in liquid form are mixed evenly to obtain a homogeneous powder. Through the drying process in an oven with a temperature of 80°C for 24 hours a dry powder is obtained. Powder is subsequently ground and calcined in the horizontal tube furnace at a temperature of 320°C for 10 hours under the flowing nitrogen gas. The obtained powder is further ground and mixed with carbon sources as much as 4wt% of the total powder. Citric acid, tartaric acid and fructose are used as the carbon source. These homogeneously mixed powders are subsequently sintered at a temperature of 800°C for 8 hours under the flowing nitrogen gas. Phase obtained from the solid-state process was analyzed by XRD. Phase composition is analyzed by Rietveld refinement that is included in the GSAS-program. The conductivity of obtained powder as cathode materials is tested by EIS (Electrochemical Impedance Spectroscopy). SEM and BET analysis tests are conducted to determine the morphology of powder which can influence the conductivity of the material.
Photocatalytic Activity of Fe-Doped ZnO/Montmorillonite Nanocomposite for Degradation of Malachite Green
Authors: Afifah Nur , Djaja Nadia Febiana , Saleh Rosari
Published: August 2015

In this study, the photocatalytic activity of pure Fe- doped ZnO and Fe- doped ZnO/Montmorillonite nanocomposite has been investigated for the degradation of malachite green under UV light irradiation. Both photocatalysts were synthesized using co-precipitation method and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier-transform infrared absorption, and electron spin resonance. The results showed that the photocatalytic efficiency is better in the presence of montmorillonite compared to pure Fe- doped ZnO. To detect the possible reactive species involved in degradation of organic dyes control experiments with introducing scavengers into the solution of organic dyes were carried out. It is found that electron plays an important role in the degradation of malachite green.
Nano-Structural Studies on Fe3O4 Particles Dispersing in a Magnetic Fluid Using X-Ray Diffractometry and Small-Angle Neutron Scattering
Authors: Taufiq Ahmad , Sunaryono  , Rachman Putra Edy Giri , Pratapa Suminar , Darminto
Published: August 2015

Ferrofluid (magnetite/Fe3O4magnetic fluid) is colloidal suspension containing Fe3O4nanoparticles dispersed in a liquid carrier. In this work, Fe3O4particles in the fluid have been prepared by a simple co-precipitation route. The nano-structural behaviors such as phase purity and crystal structure of magnetite particles in ferrofluid were studied by means of X-ray diffractometry (XRD). Meanwhile, the form and structure factors were investigated by small-angle neutron scattering (SANS) spectrometer. The XRD pattern confirmed a single phase of spinel cubic Fe3O4structure. Further XRD data analysis revealed that the magnetite has a lattice parameter of 8.38 Å. The SANS data was fitted by applying a lognormal spherical calculation as a form factor and a mass fractal model as a structure factor. It showed that the magnetite ferrofluid has primary particles of 7.6 nm in diameter with fractal dimension of 1.2, which can be associated with chain-like structure. The chain-like structured Fe3O4ferrofluid based on local natural iron sand in this work opens new opportunities to be applied for novel prospective applications.
Effect of Pb Substitution on Superconducting and Normal State Electrical Properties of Bi2Sr2CaCu2O8+σ Nanopowders
Authors: Astuti Fahmi , Baqiya Malik Anjelh , Darminto
Published: August 2015

Abstract.The powders of Bi2-xPbxSr2CaCu2O8+δ(x=0; 0.4) superconductor have been prepared by using dissolved method followed by short period of sintering and calcination process . The purpose of this research is to study about the Pb doped effect to the properties of BSCCO nanopowders especially in the electric and superconducting properties. Based on the previous result, BSCCO nanopowders have ferromagnetic properties at the room temperature. This characteristic is not appeared in bulk superconductor. The 2212 phase of Bi-based system has been formed and observed by using X-ray diffraction (XRD) measurement. The superconducting quantum interference device (SQUID) observation showed that the Bi2-xPbxSr2CaCu2O8+δ(x=0; 0.4) samples exhibited diamagnetic behaviour at the critical temperature, Tc=76 K and 78 K. The sample with partial Pb substitution exhibited stronger permanency to the external magnetic field indicating presence of flux pinning. The four point probe (FPP) measurement showed that the sample partially doped with Pb has lower resistivity (more metallic) than the Pb-free sample in the normal state.
SnO2 Films Decorated by Au Clusters and their Gas Sensing Properties
Authors: Korotcenkov Ghenadii , Brinzari Vladimir , Han S.H. , Gulina L.B. , Tolstoy V.P. , Cho B.K.
Published: August 2015

It is shown that successive ionic layer deposition (SILD) method can be used for a surface functionalizing of the SnO2 films and improving their gas sensing properties. It was found that gold clusters deposited on the SnO2 surface were active to both reducing and oxidizing gases. However, the most significant increase in the conductivity response was observed during detection of ozone. It was established that the effect of the SnO2 surface decoration by AuNPs on gas sensing characteristics depends on the number of deposition cycles, i.e. the size of gold clusters. Moreover, there is an optimal level of surface doping, and it corresponds to a very small degree of the surface coverage by gold. Models showing the promotional role of Au additives were then discussed, and the mechanism of sensitization in the SnO2:Au-based gas sensor are proposed.
Effect of Nb2O5 Addition to the Electrical Properties of Fe2TiO5 Ceramics-Based NTC Thermistor
Authors: Wiendartun  , Risdiana  , Fitrilawati  , Siregar Rustam E.
Published: August 2015

The aims of this research is to identify the effect of Nb2O5addition on the electrical properties of Fe2TiO5ceramics-based NTC thermistor.The concentration of Fe2O3and TiO2was proportional to Fe2TiO5, whereas the concentration value of Nb2O5were 0, 0.5 and 1.0 mole %, respectively. Within two hours, the mixed powder was pressed at 4 ton/cm2to form pellets and sintered at 1300 °C in air. It can perceived from the XRD data that the sintered ceramics had single phase of Fe2TiO5, pseudobrookite. From SEM data, it is found that addition of Nb2O5decreases the grain size. The addition of Nb2O5increases thermistor constant, activation energy and electrical resistance of Fe2TiO5ceramics. The values of thermistor constant of Nb2O5added-Fe2TiO5ceramics were relatively large, indicated that the ceramics were aplicable as the NTC thermistor.
Comparative Study on Photocatalytic Performance of (La,Fe) and (Ce,Fe)-Codoped ZnO Nanoparticles
Authors: Djaja Nadia Febiana , Saleh Rosari
Published: August 2015

The present study evaluates the photocatalytic degradation of congo red as a model of organic pollutant over LaFe- and CeFe-codoped ZnO nanoparticles under UV light irradiation. Both photocatalysts were synthesized using co-precipitation method and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, diffuse reflectance spectroscopy. The photodegradation efficiency of congo red using two 20W UV lamp was higher for LaFe-codoped ZnO nanoparticles compared with CeFe-codoped ZnO nanoparticles. Photocatalytic mechanism was investigated by measuring the photocatalytic degradation rate in the presence of ammonium oxalate, natrium sulfate, tert-butyl alcohol as photogenerated holes, photogenerated electrons and hydroxyl radical species scavenger. The results revealed that electrons are the main species in the photocatalytic process.
Reduction Kinetics of Thermally Reduced Graphene Oxide Thin Films
Authors: Fitrilawati  , Syakir Norman , Aprilia Annisa , Liu Zhou Yang , Feng Xin Liang , Bubeck Christoph
Published: August 2015

We report an experimentalstudy of thermal reduction of graphene oxide (GO) under nitrogen flow.Ultrathin films of GO were prepared on quartz glass substrates by spin-coatingfrom 3 mg/ml aqueous solutions of GO. These films were annealed at 50 °C under vacuum overnight before thermal reduction.The films were exposed to temperatures of 100 °C, 150 °C, 200 °C, 300 °C, 400 °C, 500 °C and 800 °C under nitrogen flowing. We used UV-Vis absorption spectroscopy tomonitor the change of absorption spectra caused by thermal reduction. We observed a significant change ofabsorption spectra due to formation of reduced graphene oxide (RGO). We found that thermal reduction startedalready at 100 °C, but proceeded significantly faster at heating temperatures higherthan 200 °C.
Electron Microscopy Study of Grain Boundary Behavior in Pb-Free Solder Materials for Mitigation of Whiskers
Authors: Kuwano Noriyuki , Horikami Sadanori , Linus Marina
Published: August 2015

The changes of microstructure in pure-Sn after deformation were investigated by electron microscopy. Two types of specimens were prepared: Sample-1; pure-Sn/Fe-42Ni, Sample-2; single crystalline pure-Sn. The growth of curling whiskers on Sample-1 was observed in-situ in a scanning electron microscope (SEM). A thin foil specimen of the curling whisker was made with a focused ion beam (FIB) mill. Transmission electron microscope (TEM) analysis confirmed that the curling whisker was of a single crystal regardless of its external shape. New models for growth process of a bent single-crystalline whisker were proposed. The models are composed of epitaxial growth and recrystallization. Electron back scatter diffraction (EBSD) analysis was performed for Sample-2. The results of EBSD strongly suggested that recrystallization proceeds even at room temperature. These experimental results are very important to understand the behavior of dynamical deformation and recrystallization of Sn metal, and useful in consideration the mitigation of whiskers.
Phonon Properties of Co:TiO2 Single Crystal
Authors: Setiadi H. , Prasetyo A. , Suendo V. , Nugroho Agustinus Agung
Published: August 2015

Phonon properties of cobalt doped rutile TiO2single crystal was investigated using a Raman Spectrometer with laser wavelength at 532 nm in the temperature range from 140 K to 750 K. The phonons modes of B1g,Eg,and A1gwith the energy of 140 cm-1, 450 cm-1and 600 cm-1are clearly observed. The second order phonon process is also observed at the energy of 250 cm-1.The temperature dependence of the A1g, Egmodes become stiffen as lowering the temperature, while the B1gmode becomes soften. The temperature dependence of the B1gis found to be a signature as the effect of doping. Based on the harmonic model, this is explained due to the change the Ti-O coupling strengths of TiO6octahedral. A larger change is found for the longer distance of the Ti-O bond.
Bone Scaffold Based on Biopolymer/Carbonate Apatite by Freeze Drying Method: Synthesis, Characterization, and In Vitro Cytotoxicity
Authors: Daulay Abdul Halim , Indrani Decky Jusiana , Aufan Muhammad Rifqi , Ramelan Aditianto , Siswosuwarno Mardjono , Purwasasmita Bambang Sunendar
Published: August 2015

The global need of biomaterial products especially in bone clinical application increases every year. The gold methods like autograft and allograft have some limitations in the application such as the availability of donor sites, antigenicity issues, the high cost, etc. To solve the problems, many researches and activities in the field of biomaterial have been conducted continuously in the past decades to develop the proper synthetic materials for bone substitutes which have properties similar to bone tissue. In this research, the synthesis of biocomposite for bone scaffold application prepared by freeze drying method has been done successfully. The materials used are biopolymer (alginate and chitosan) and bioceramics (carbonate apatite) with certain mixing variations. SEM result showed that the pores obtained by freeze drying method can mimic the pores of actual bone thus they will be able to resemble cells microenvironment, enhance interface interaction, and support cell proliferation. The existence of carbonate apatite on the scaffold’s surface can be observed with particle size of 0.05 – 1 μm and has been dispersed evenly. These results are in good agreement with FT-IR analysis that indicates the presence of PO43– functional group on the scaffold at wave numbers 569 and 1041.56 cm–1 and CO32– functional group at wave number 1411.89 cm–1. The in vitro biological evaluation of HeLa cells which exposed to extract solution of scaffold (in some variations of concentration) indicated that the scaffold obtained was not cytotoxic to the HeLa cells.
Sintering Behavior and Diametral Tensile Strength Properties of Hydroxyapatite-Zirconia Composites
Authors: Pujiyanto Eko , Widyo Laksono Pringgo , Sagiran
Published: August 2015

. The aim of this study is to evaluate the sintering behavior and diametral tensile strength properties of hydroxyapatite-zirconia (HA-ZrO2) composites. HA powder were synthesized from gypsum waste with diammonium hydrogen phosphate (DHP) solution via microwave-precipitation treatment. HA mixed with various amounts of ZrO2 (0, 20, 30 and 40 wt.%) for six hours. HA-ZrO2 powder were molded in a metal die and pressed at 100 MPa. The green bodies were sintered for 2 hours at temperature 1450°C. Characterization of HA and HA-ZrO2 composites were conducted by XRD, XRF and SEM-EDX. The apparent porosity of HA-ZrO2 composites were measured using the Archimedes method. Diametral tensile strength testing of HA-ZrO2 composites were loaded at a crosshead speed of 5 mm/min. The results of the characterization of HA powder are the main (h k l) indices for HA are: (2 1 1), (2 0 2) and (0 0 2), Ca/P molar ratio is 1.71, level of purity is 88.68 %. The main (h k l) indices for HA-ZrO2 composites are: (2 2 0), (0 2 10) and (2 0 20). Porosity of HA-ZrO2 composites values in the range of 39.59-19.82%. Diametral tensile strength of HA-ZrO2 composites increased from 4.96 to 7.77 MPa when amounts of ZrO2 increased up to 40 wt%. This phenomenon is caused by porosity decrease and crack deflection.
Effect of Rolling Temperature on Annealing of aa1050 Aluminium Alloy
Authors: George Sarah , Mias Candice
Published: August 2015

Commercially pure, dilute aluminium alloys, such as AA1050, dynamically generate sub-grains during cold rolling. If AA1050 is rolled at cryogenic temperatures (liquid nitrogen), this large decrease in temperature minimises the occurrence of dynamic recovery during rolling. The result is that the material has a large amount of stored energy and a high dislocation density, thereby giving it a high strength. This research looks at the recovery and recrystallization processes during annealing after cryo-rolling, and compares the formation of sub-grains and recrystallized grains to those where rolling was performed at room temperature. The type of dislocation structure that forms during the rolling process directly affects the evolution of the microstructure post-deformation. Owing to the extreme temperatures of cryo-rolling, the dislocation structure cannot undergo dynamic recovery. Instead, a distinct cell-like structure forms, with dense dislocation walls that are high energy. During subsequent annealing, the driving force for recrystallization is increased with a decrease in the rolling temperature, with the cryo-rolled material having a greater number of nucleation seed and consequently, a fine grained recrystallized microstructure.
Heat Treatment of Titanium-Aluminum-Compounds Made by Co-Extrusion of Asymmetric Compound Profiles
Authors: Striewe Barbara , Grittner N. , von Hehl Axel , Nürnberger Florian
Published: August 2015

Combining different materials allows designing lightweight structures with tailor-made properties at the macroscopic as well as at the microscopic scale. In this context co-extrusion by lateral angular co-extrusion process (LACE) offers a great potential for advanced products by joining different light alloys, such as titanium and aluminum alloys. While titanium alloys show particular high mechanical strength values and a good corrosion resistance, aluminum alloys feature a considerable high specific bending stiffness at low materials costs. Within the presented research study metallic compounds were manufactured by co-extrusion using a LACE process. Since the mechanical properties of metallic composites highly depend on the existence and formation of an intermetallic layer, the bonding zone of the compounds were investigated. Experiments were carried out at the example of the material combinations Al99.5 & Ti99.2 and AlSi1MgMn & Ti99.2, respectively. The results of co-extruded samples concerning the intermetallic layer that was formed during heat treatment were compared with those directly after the co-extrusion. The investigations were focused on the formation of the bonding zone after both co-extrusion and the subsequent heat treatment. The bonding zone was characterized by scanning electron microscopy as well as electron probe micro analysis. Finally, the bond strength of each compound variant was determined and evaluated.
Fatigue Behaviour of Titanium Transition Structures for Advanced Carbon Fibre Reinforced Plastics (CFRP)-Aluminium Joints
Authors: Kunze Arne , von Hehl Axel , Schumacher Jens , Woizeschke Peer , Zoch Hans Werner
Published: August 2015

Modern lightweight construction containing hybrid materials and structures allow the improvement of a wide range of density specific properties. In this regard, the great potential of structures consisting of carbon fibre reinforced plastics (CFRP) and aluminium (Al) is far from being exhausted. In order to exploit this potential, novel joint concepts are necessary, enabling simultaneously an economic structure manufacturing. As a more advantageous alternative to conventional riveting, the development of integral joint concepts with material oriented design that includes high load capacity and improved corrosion resistance has currently high priority for aviation industry. The research group Schwarz-Silber (FOR 1224) funded by the Deutsche Forschungsgemeinschaft (DFG) and based at the University of Bremen set itself the goal to explore and develop interface structures for advanced CFRP-Al compounds. Considering textile, welding and casting techniques, novel joint concepts will be designed, dimensioned and produced within six interdisciplinary projects. Experimental and numerical investigations support the validation and enhancements of the developed solutions. Regarding a joint concept combining textile and welding techniques, basic investigations have been performed. The concept of coupling Al sheets with CFRP panels by means of transition structures made of titanium (Ti) sheets, being bonded to the CFRP side and welded to the Al side, has already been analysed under static tensile loads. This paper presents the failure behaviour of such entire Al-Ti-CFRP joints under cyclic loads. The failure probability is calculated by using the approach of maximum likelihood.
Achievements in Magnesium Alloy Research
Authors: Easton Mark , Gibson Mark , Zhu Su Ming , Yang Kun , Abbott Trevor
Published: August 2015

Research into magnesium die-cast alloys from the Mg-Al-(Zn), Mg-Zn-(Al), Mg-rare earth (RE) and Mg-Al-RE systems is discussed. Particular attention is paid to factors influencing mechanical properties and castability. The nature and level of alloy addition is in all cases an important determinant of castability (cracking and fluidity) and mechanical properties (strength, ductility and creep resistance). The interplay of these factors shows considerable variation between different alloy systems.
PVD Hard Coatings for High Loaded Al Alloys – Potentials and Limitations
Authors: Buchwalder Anja , Zaulig Erik , Zenker Rolf , Liebich Jürgen
Published: August 2015

PVD hard coating is a well-known surface treatment technology for steels to improve wear resistance and, to some extent, corrosion resistance. In principle, hard coating can be carried out for Al alloys, but due to the natural oxide layer and the insufficient load-bearing capacity of the soft base material, the application of this technology for wear protection of components is not regarded as being particularly promising. The research activities described in this paper focused on electron beam (EB) surface alloying with a Co-based additive, and the influence of two different hardness levels (270HV0.1 and 390HV0.1) on the improvement of the local load-bearing capacity of Al alloys with thin PVD hard coatings. A further focus of this research was on the material-specific aspects of the coating deposition. Compared to steels, the hard coated surface of Al alloys is rougher and the measured adhesion of the coating is significantly lower. For this purpose, different technological PVD parameters (e.g. Ti interlayer, deposition temperature, and time) were adapted to optimize the coating properties – especially adhesion. The paper deals with comparative studies of single (PVD hard coating of Al base material) and duplex treatment (EB alloying of Al base material and subsequent PVD hard coating) by means of improvement of the coating and compound hardness, friction and wear behavior (pin-on-disc test), as well as the corrosion resistance (potentiodynamic measurements in 0.05M H2SO4). While the level of improvement in wear resistance as a result of the duplex treatments strongly depended on the adhesion of the thin coatings, the corrosion behavior was strongly influenced by the PVD deposition process and coating thickness.
A Novel Process for Fabricating Aluminium Alloy Porous Structure for Possible Application in Antimicrobial Filtration
Authors: Hamweendo Agripa , Botef Ionel
Published: August 2015

This paper presents a novel process for fabricating micro-porous Aluminium (Al) alloy structures with possible application in antimicrobial filtration of drinking water which is contaminated with pathogenic micro-organisms responsible for water-borne diseases. This process is an integration of cold spray (CS) with the alloy-de-alloy phenomenon. In this process, the Al, Aluminium oxide () and Copper (Cu) powders with antimicrobial capabilities were mixed and deposited directly onto to a substrate using CS. To create porosity in the Al-Alumina-Cu coating, pores were innovatively engineered by alloying the Al--Cu with pore forming agents followed by preferential de-alloyed of these agents. The resulting structures have promising microstructural composition and porosity which make them favourable for antimicrobial filtration of contaminated drinking water. Consequently, this research demonstrates that via CS, a novel process was developed for fabricating porous Al-Alumina-Cu alloy metal foam for application in decontamination of drinking water.
Evolution of High Precision Manufacturing of Contact Lenses
Authors: Olufayo Oluwole , Abou-El-Hossein K.
Published: August 2015

Today’s contact lens professionals must familiarise themselves with the various contact lens manufacturing methodologies that are capable of producing high accuracy optical products for their patients. Contact lens manufacturing dates back to the 19thcentury with the development of glass contact lenses and later evolved to various types of optical polymeric materials. The recent advances in the manufacturing of contact lenses can be attributed to the development of advanced polymeric materials and high precision processing technologies. Two basic techniques are identified for contact lens manufacturing. They are moulding method and ultra-high precision machining. Ultra-high precision machining is employed for direct shaping of contact lenses or for making mould inserts that will be used further in lens injection. Mould inserts can be made from high hardness steel, nickel plated steel, aluminium or other nonferrous alloys. Advanced light metal optical aluminium alloys provide a high integrity mould with fine microstructures for optical lens production. This review paper provides a chronological view of the evolution of contact lens manufacturing and identifies the importance of a recently developed aluminium alloy in the production of mould inserts for high quality contact lenses.
Role of Surface Reactivity in Processing and Performance of Magnesium Alloys
Authors: Czerwinski Frank
Published: August 2015

The surface reactivity of magnesium alloys at high temperatures required for their processing in solid, semisolid and liquid states is reviewed emphasizing presently existing barriers of its understanding and control. In addition to general aspects of magnesium oxidation, other forms of reactivity such as ignition and flammability are discussed. Since surface oxide, composed of pure MgO, does not offer a sufficient protection, operations of raw alloy melting and component manufacturing require protective atmospheres what has detrimental implications on process economy and product performance. Efforts to develop ignition resistant magnesium alloys through modification of their chemistry are described with a particular role of rare earths and other elements with high affinity to oxygen. It is concluded that all forms of magnesium reactivity in solid and liquid state could be explained through diffusion characteristics of surface oxide formed during processing and service.
Softening Behavior of Ti6Al4V Alloy during Hot Deformation
Authors: Souza Paul Micheal , Beladi Hossein , Rolfe Bernard , Singh Rajkumar , Hodgson Peter  D.
Published: August 2015

The effect of strain rate and strain on the hot compression behaviour of Ti6Al4V has been analysed to understand the microstructural evolution and restoration behaviour. Cylindrical samples with partially equiaxed grains were deformed in the α+β region at different thermo-mechanical conditions. EBSD has been used to study the microstructural behaviour and the restoration mechanisms. The microstructural evolution showed a complex restoration behaviour, where both fragmentation and nucleation of new grains have been observed. The volume fraction of the equiaxed grains increased with an increase in the strain, but oppositely decreased with the strain rate. At the same time the average grain size of the equiaxed grains decreased with an increase in both the strain and strain rate. The measured activation energy for deformation revealed a good agreement with reported values in the literature.
Controlling the Formation of Iron-Bearing Intermetallics in Wrought Al Alloys by Melt Conditioned DC (MC-DC) Casting Technology
Authors: Li Hu Tian , Patel J.B. , Kotadia H.R. , Fan Z.
Published: August 2015

With the increasing use of recycled aluminium alloys from the end-of-life products more and more iron is accumulated into the compositions of alloys. Sometimes, recycling causes the iron levels to increase beyond the set target levels for down-stream processing. The only way to deal with this impurity currently in industry is to increase the primary aluminium added to the furnace to dilute the melt and re-add all other elements or cast it for re-melting or extrude it for products that is not surface finish critical or required higher corrosion resistance. Formation of small well dispersed spherical a- or small b- Fe-bearing intermetallics, which can be homogenised for shorter times and has no negative effect on downstream processing, would be promising even if the iron levels are above the targeted compositional limits. In the present paper, fine and dispersed Fe-bearing intermetallics have been achieved by Melt Conditioned DC (MC-DC) casting technology, instead of coarser Fe-bearing intermetallics forming network like morphology in the DC castings with grain refiner additions (DC-GR). This suggests feasibility of an increased tolerance of iron levels by melt conditioned DC casting technology.
3D X-Ray Inspection of a Radio Controlled Airplane Engine
Authors: du Plessis Anton , Gerhard le Roux Stephan , van Rooyen Herman
Published: August 2015

This paper describes a typical 3D X-ray micro computed tomography (microCT) analysis of light metal parts, from a radio controlled airplane engine. This case study shows the power of 3D X-ray inspection and analysis for this type of material, including information about the size and location of casting defects, the location of turbine blade balancing weights and dimensional measurements indicating the axle was not perfectly centre. Advantages and limitations of the method for light metals are described in general
Light Metals for the Functional Requirements of Developing World Lower Extremity Paediatric Prosthetics: A Review of Current Material & Technology Trends
Authors: Mangera Taahirah , Govender Gonasagren , Conning Mariette
Published: August 2015

The functional requirements of lower extremity paediatric prostheses in developing regions and the materials used in the manufacture thereof is presented in this paper. Specific advantages and disadvantages of materials used in relation to the African paediatric amputee are highlighted. The paper examines the critical issues for which further research and development is needed into material and manufacture tailoring to meet the functional requirements of a paediatric prosthetic. The applicability of light metal alloys in meeting these requirements is emphasised.