bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigate the Reliable and Accurate Pattern Transfer of IDE Silver Electrode Coated with Zinc Oxide Microwire for Biosensor Application
Authors: Prasad R. Haarindra , Foo Kai Long , Hashim U.
Published: April 2014

This paper illustrate a facile route to fabricate and develop zinc oxide microwire which acts as transducer for biosensor application. Pattern transfer process is conducted on the wafer substrate by using conventional photolithography process to form IDE electrode. The substrate is coated with positive photo-resist (PR) and exposed for UV light for 10 seconds. After development, the unexposed area is etched by using hydrochloric acid, HCI. In this study, zinc oxide material have become a remarkable choice for bio-sensing development due to large band gap and tailor for bio-molecular application. Zinc oxide solution was prepared through chemical route, that is by using sol-gel method. The coated ZnO films were annealed in furnace at 500°C for 2 hours. ZnO seed solution undergoes hydrothermal growth to synthesize ZnO microwires. ithThe substrate used for this study is p-type silicon wafer which is oxidized. SiO2 layer is used because it acts as an insulator which is very essential for an electronic device to avoid electrical leakage and improve electron mobility. Further investigation of morphological and electrical characterization is conducted through SEM and I-V test .Average size diameter of Zno microwire is 0.45μm and exhibit 900μA of current at 5V.
Pattern Transfer of 1μm Sized Microgap and Microbridge Electrode for Application in Biomedical Nano-Diagnostics
Authors: Rao Balakrishnan Sharma , Hashim Uda
Published: April 2014

We present a new design of biochip for application in clinical diagnostics by using a conventional method of pattern transfer process in microelectronic fabrication. Although there are many advanced techniques available to produce nanostructures such as electron beam lithography (EBL), ion-beam lithography (IBL), focused ion beam milling and nanoimprint lithography, these methods often requires high maintenance costs, time consuming and very complicated compared to conventional photolithography. This conventional technique is still a good choice for a feature size more than 1 micron. In this work, microbridge and microgap design from chrome mask are transferred on silicon wafer to fabricate a biochip. The pattern transfer of the first mask of electrode is presented in this paper to test the repeatability of pattern transfer during photolithography process. Therefore, during the process, the resolution and precise alignment factors are taken into account to prevent circuit and device failure. Post-exposure bake time and development limitations are recorded for both designs.
Analysis of Electric Double Layer on Thin Film Lubrication with Partial Slip
Authors: Rao T.V.V.L.N. , Sufian S. , Mohamed Norani Muti
Published: April 2014

This paper presents a model of electro-viscosity considering effects of electric double layer on thin film lubrication with partial slip. The apparent viscosity and modified Reynolds equation are derived with consideration of electric double layer with partial slip. The apparent viscosity includes the combined effects of the electro-viscosity, the viscosity of bulk fluid and slip length. The electro-viscosity depends on the zeta potential. The effects of electric double layer with partial boundary slip on load capacity are analyzed for one-dimensional slider bearing. The electric double layer leads to an increase in apparent viscosity of lubricant and hence load capacity in thin film lubrication. Electric double layer with partial slip on parallel bearing surfaces increases the bearing load capacity.
Characterizations of Electron Beam Evaporated Silicon Thin Films on Plastic Substrates for Solar Cells Applications
Authors: Ang P.C. , Ibrahim K. , Pakhuruddin M.Z.
Published: April 2014

Samples of thin film silicon (Si) on low cost polyethylene terephthalate (PET) plastic substrates were prepared by electron beam (e-beam) evaporation technique. Five samples of different thicknesses were deposited. Structural, optical, surface morphology and electrical characterizations were then carried out on these samples by energy dispersion X-ray (EDX) spectroscopy, high resolution X-ray diffraction (HR-XRD), UV spectrophotometer, atomic force microscopy (AFM) and four-probe meter. EDX spectra for these as-evaporated Si thin films on PET showed that the peak at 1.7398 eV belongs to Si atom which confirms the existence of the Si thin film layer. HR-XRD result showed that the chosen sample was highly amorphous. The transmission and reflection were carried out from wavelength 200 nm to 2000 nm and the optical band gap of the samples was calculated by Taucs relations. The root mean square (RMS) of surface roughness was low (smooth morphology) and found to be independent to the thickness of the film. The films were found to be highly resistive due to their intrinsic nature (no doping applied during the deposition). The effects of the properties towards thin film solar cells fabrication were subsequently discussed.
Green Catalytic Approach for the Synthesis of Functionalized Nanocellulose from Palm Tree Biomass
Authors: Hamid Sharifah Bee Abd , Karim Mohammad Ziaul , Ali Md Eaqub
Published: April 2014

Oil palm is a major agricultural product in Malaysia and it covers approximately 5 million hectares of land. Palm tree biomass is a by-product of oil palm cultivation. Biomass is a complex structure composed of cellulose, hemicelluloses and lignin. Cellulose, which gives the mechanical properties to the natural fiber, is organized in micro-fibrils enclosed by the other two main components: hemicellulose and lignin. Cellulose microfibrils can be found as intertwined microfibrils in the cell wall (220 μm in diameter and 100 40,000 nm in length). Cellulose microfibrils are in turn exist in cellulose nanofibers having diameter of 550 nm and length several millimeters conformed by nanocrystalline domains and amorphous regions. Nanocellulose, which is a degradation product of cellulose, has recently come to public attention because of its great mechanical properties combined with low molecular weight, renewability and biodegradability. Another advantage of nanofibrillar cellulose is that their production does not interfere with the food chain, therefore, they can be considered as socially sustainable raw materials. However, before the nanocellulose can be fully utilized to fabricate smart and environmentally friendly new high-tech products. Most common applications of nanocellulose are for polymer composite, bioplastics, films, foams, gels, cosmetics, dimensionally stable thickener and emulsion, implant material, biodegradable tissue scaffold, suture, drug delivery vehicle, filter paper, speaker membrane, battery membrane, concrete, drilling muds & enhanced oil recovery, water treatment, etc. Several methods have been proposed for the extraction/preparations of nanocellulose which involve extensive chemical and mechanical treatments which are not environmentally friendly. This paper reviewed various methods along with their limitations for the controlled structure synthesis of functionalized nanocellulose from palm tree biomass. The green catalytic approaches are schematically outlined.
Modified Polyol-Mediated Synthesis of Doped TiO2 Nanoparticles as the Photoanode in Dye Solar Cells (DSCs)
Authors: Bashardoust Sattar , Norani Muti Mohamed , Ong Boon Hoong , Zaine Siti Nur Azella
Published: April 2014

Synthesis of nanoscale TiO2 exhibiting specific properties of electron or ion conductivity is critical to improve the performance of dye solar cells (DSC). This paper presents the modified polyol-mediated synthesis of doped TiO2 nanoparticles. TiO2 samples were doped with cobalt (Co) and nickel (Ni) and the effects of calcination temperature (550 °C and 650 °C) on the crystallinity of pure samples were investigated. X-ray diffraction (XRD) analysis was used to determine the effect of dopant in lattice structure. The morphology and Crystal structure of TiO2 samples and their chemical analysis was conducted using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectrometer respectively. Results show agglomeration of spherical particles in all doped samples. Crystal structure in the doped samples reveals modified phases and major crystal phase identical to anatase. It is observed that the molar ratio of water to metal can control the nucleation and growth and prevents significant agglomeration of nanoparticles. More effective doping was recorded for samples with 0.5 % concentration. Effective hydroxyl group is detected in both 0.5% Ni and Co promising good photocatalytic material. SEM images of 0.2% Ni-doped sample shows smallest average particle size.
Performance of P3HT:PCBM Organic Solar Cell with ZnO Buffer Layer
Authors: Alias M.S , Kamaruddin Sharul Ashikin , Norhidayah Che Ani , Sarip Nurulnadia , Nayan Nafarizal , Zainizan Sahdan Mohd
Published: April 2014

In this paper, we explore the characteristics of bulk heterojunction solar cell based on poly (3-hexyl thiophene) [P3HT] and [6,6]-phenyl-C61-butyric acid methyl ester [PCBM] by introducing a buffer layer with device configuration of ITO/ZnO/P3HT:PCBM/Au. Nanostructured ZnO with individual diameter around 20-50 nm was used as the buffer layer and its effects on the short circuit current density, Jsc and open circuit voltage, Voc were investigated. It was found that, the electrical characteristic of the organic solar cell was obviously changed by introducing the buffer layer. Solar cell characteristic with Voc of 0.3939 V was obtained but the Jsc was very small. The surface topology of the P3HT:PCBM was investigated using an atomic force microscopy (AFM). ZnO nanoparticles were observed using a field emission scanning electron microscope (FESEM) and the electrical properties of the solar cell was measured using a solar simulator with a current – voltage (I-V) measurement system.
Design Development of Acoustic Waves Based Sensitive Sensors for Escherichia coli O157:H7 Detection
Authors: Ten Seng Teik , Hashim Uda , Sudin Ahmad , Liu Wei Wen , Foo Kai Loong , Salleh N.H.M. , Hisham Hashim , Nazwa T.
Published: April 2014

Food contamination has become critical issue and is being worse due to the insensitive detection devices. One of the dangerous food contaminations is by Escherichia coli (E.coli) O157:H7, one of the harmful bacterial pathogens which is distributed in soil, marine and estuarine waters, the intestinal tract of animals, or water contaminated with fecal matter. A small amount of E.coli with the dose fewer than 100 organisms in food products or water is enough to cause serious gastrointestinal illness to human. Hence, the ultra-high sensitive, label free biosensors have been designed in this research for the low concentration E.coli detection. Surface acoustic waves (SAW) devices have been initially developed and used for the high-volume low-cost TV component. Due to the ultra-sensitivity to the surface perturbation, SAW based devices have been modified to be sensors. Initially, SAW sensors were developed for gas detections and have been moving towards biological detections recently. Shear horizontal surface acoustic wave (SHSAW), one of the SAW based types is most suitable for the liquid based application as it has the advantage of acoustic energy is not being radiated into liquid. However, the main SHSAW design components are the operating frequency and wave length. These are strictly depended on the inter digital transducers (IDTs) design. Therefore, this paper is presenting the IDTs design concept and pattern development by using computer aid design (CAD) software.
Nanocoral PbS Films Schottky Solar Cell
Authors: Obaid A.S. , Dihe Alaa Ahmed , Salih B.M. , Hassan Z. , Al-Douri Y. , Bououdina M.
Published: April 2014

This study reports on the fabrication of a Schottky solar cell with a cross-sectional schematic: ITO/PbS/Al with a commercial transparent conductive ITO and a p-type PbS absorber layer deposited by using a thermal evaporator. The structural and optical properties of constituent films are presented. X-ray diffraction showed that the thin films are polycrystalline. By using scanning electron microscopy, this study showed that the films possessed a uniform surface morphology over the substrate, and the films exhibit a nanocoral structure. Open circuit voltage,short-circuit current density and characteristics were studied under 30 mW/cm2 solar radiation.
Measuring Radon Concentration Levels in Fertilizers Using CR-39 Detector
Authors: Aswood Murtadha Sh. , Jaafar Mohamad S. , Bauk Sabar
Published: April 2014

Radon concentrations in fertilizer samples collected from agricultural areas in Cameron Highlands and Penang, Peninsular Malaysia were studied throughout this paper. The concentrations were measured using a sealed-can technique based on the CR-39 SSNTDs. Results indicate that the concentration of radon in the phosphorus sample was the highest whereas the minimum values were found in CDM (Cow dung manure). The levels of radon concentration were found to lie within the range of (634.0151.42 to 79.2523.24) Bq m-3.
Green Catalytic Approach for the Synthesis of Platform Chemicals from Palm Tree Lignin
Authors: Hamid Sharifah Bee Abd , Shilpy Mariom Zamila , Ali Md Eaqub
Published: April 2014

Lignin is the second most abundant naturally occurring macromolecule found in plant cell-wall, vascular components and woody stems. It is the largest renewable source of aromatic biopolymer. However, lignin is recalcitrant to be broken down by most chemicals. This is because of its complicated heterogeneous molecular structure. However, lignin depolymerization has huge potentials for the synthesis of a number of useful chemicals, perfumes and pharmaceuticals and toiletries. The oxidation products of lignin are important precursors for pulp/paper and food industries, synthetic thin films. Vanillin, veratryl aldehyde and para-benzoquinone are the oxidation products of lignin. These chemicals are the precursors of optically active alcohol, ketone, violuric acid and benzaldehyde. However, the oxidation of biolignin has been remaining a challenging task. Green catalytic approaches might be an interesting solution for the selective depolymerization of lignin into various platform chemicals. Metal oxide/silica supported nanoporous gold has received strong attention as green catalyst for the transformation of various natural polymers. Mesoporous metal oxide/silica provide enlarged surfaces for the breakdown of C-C, C-H and C-OH bonds. This paper has reviewed various green catalytic approaches for the control depolymerization of biolignin into platform chemicals.
Transmission of Microwave Signal through Metal-Oxide Thin Film of Energy Saving Glass Using Different Shape of Frequency Selective Structure
Authors: Lim Huey Sia , Nayan Nafarizal , Sahdan Mohd Zainizan , Dahlan Samsul Haimi , Zainal Abidin Zuhairiah , Ismail Muhammad Yusof , Che Seman Fauziahanim , Suaidi Mohd Kadim , bin Ahmad Fauzi , Rosli Zulkifli Mohd , Mohd Juoi Jariah , Kiani Ghaffer I.
Published: April 2014

Metal oxide thin films are widely used for energy saving glass coating. This coating has the ability of blocking the infrared signal while being transparent to other visible part of the spectrum. However, there is one critical disadvantage of this metal oxide coating which it attenuates useful radio frequency and microwave signal such as GSM mobile signal, personal communication, GPS signal through them. These important microwave signals are fall within the range of 800 MHz to 2200 MHz. Frequency selective structure has been applied to solve the attenuation of microwave signal. With the adding of frequency selective structure, it can bring huge improvement of the transmission loss through it. Computer simulation using CST software is used to investigate the transmission loss through the metal oxide coated glass. The frequency selective structure will be etched out from the metallic oxide coated on the glass. Results showed that different shape of the structure will have different peak transmission loss through the glass. When cross dipole and circle shape been simulated using CST software, it can clearly see that the transmission lost and peak frequency had changed drastically. Then, triangle and pentagon shape also have different transmission through it. In addition, conductivity and electrical properties of coated metal oxide thin film is also very important. The transmission through the different ohmic sheet resistance of metal oxide thin film was also investigated. The sheet resistance value was obtained from the reported experimental results. Simulated results showed that full width half maximum, maximum transmission loss and peak frequency loss was very much dependent on the metal oxide sheet resistance. Therefore, the control of the thickness and oxygen content in metal oxide thin film are very much important to optimize the transmission loss through it for energy saving glass applications.
Evaluation of the Hourly Global Solar Radiation on a Horizontal Plane for Two Sites in Algeria
Authors: Salmi Mohamed , Bouzgou Hassen , Al-Douri Y. , Boursas Abdelhakim
Published: April 2014

We present three models for the estimation of hourly global solar radiation for two sites in Algeria, namely: Djelfa (Latitude 34.68°N, Longitude 3.25°E, Altitude 1126 (m)) and Ain Bessem (Latitude 36.31°N, Longitude 3.67°E, Altitude 629 (m)). The models are: the Gaussian distribution model, the model by Collares-Pereira-RabI and the H.A. model (Hourly absolute modelling approach). The experimental assessment was done using recorded values of the hourly global solar radiation on a horizontal plane during the period 2000-2004. The obtained results show a close similarity between the solar radiation values calculated by the three models and the measured values, especially for the first model. The experimental validation shows promising results for the estimation and precise prediction of the hourly global solar radiation.
Taguchi Optimization of a SiGe/Si Quantum Dot SOI-Based Lateral PIN Photodiode
Authors: Menon P. Susthitha , Tasirin Siti Kalthom , Ahmad Ibrahim , Abdullah Siti Fazlili
Published: April 2014

A high performance lateral silicon photodiode was designed on a Silicon–on-insulator (SOI)-based substrate with SiGe/Si quantum dot technology. The device has the potential of being a serious candidate for applications in sensing applications as well as in optical fiber communications. Five device process parameters and two device noise factors were identified to make the virtual device design insensitive to variation in the selected fabrication parameters. An L9 array from Taguchi method was used to optimize the device design. The simulator of ATHENA and ATLAS were used for photodiode fabrication process and electrical characterization, respectively. The results obtained for responsivity and frequency response after the optimization approach were 0.36 A/W and 21.2 GHz respectively which correspond to the optimization value for the intrinsic region length of 6 μm, photo-absorption layer thickness of 0.505 μm, incident optical power of 0.5 mW/cm2 and bias voltage of 3.5 V. As a conclusion, the optimum solution in achieving the desired high speed photodiode was successfully predicted using Taguchi optimization method.
Upper Extremity Vein Graft Monitoring Device after Surgery Procedure: A Preliminary Study
Authors: Lee Hoi Leong , Shahriman Abu Bakar , Za'aba Siti Khadijah , Khairunizam Wan , Roohi S. Ahmad , Zuradzman Mohamad Razlan
Published: April 2014

In most cases, surgical vein bypass or interposition vein grafting was used in both primary management of crush-avulsion amputations and on intervention for rehabilitating the patency of occluded arteries via microvascular surgery. However, surgical revascularization has significant shortcomings, principal among which is the high rate of accelerated thrombosis that develops in arterialised vein graft which renders the vein graft susceptible to acute occlusion and eventually give rise to graft failure. Evaluaion and detection of vein graft failure is essential as that will be the starting point for the clinician to make the diagnosis and safeguard patency of implanted vein graft which would otherwise fail. Unfortunately, most of the available diagnostic and monitoring tools available in the market are expensive, hence not all the hospital, private clinic and others medical centers that fully-equipped with these type of equipments. The objective of this study is to design and develop a low-cost and non-invasive vein graft monitoring prototype that able to provide high accuracy in predicting the vein graft patency and meanwhile providing the short-term monitoring on vein graft right after surgery procedure. Impedance plethysmography (IPG) was employed to measure pulsatile changes in longitudinal impedace to quantify arterial blood flow and pulsatile blood volume. Tetra-polar electrode measurement system was implemented by introduce a constant 1-mA AC current (I) at frequency of 100 kHz in the two outer electrodes. The voltage (V) is measured between the two inner electrodes, and the resulting impedance (Z) is calculated using Ohm’s Law. Arterial blood flow and pulsatile blood volume can then be estimated using impedance related volume conduction equation. By measuring the changes in electrical bioimpedance which can be used to derive important hemodynamic variables, it allows the postoperative graft surveillance and early detection atherosclerosis and thrombosis as well as estimate its severity that leads to the vein graft failure.
Conventional to Nano-Green Adsorbents for Water Pollution Management - A Review
Authors: Ali Md Eaqub , Ullah Mahbub , Hamid Sharifah Bee Abd
Published: April 2014

Pure and clean water is a must for living a healthy life. However, the increasing influence of urbanization, industrialization, domestic and agricultural activities, is continuously adding both conventional and newly emerging pollutants to the earth's water bodies, seriously affecting both the terrestrial and aquatic flora and fauna. Thus water pollution has become a major issue in the global perspectives. In the last few decades, numerous methods, such as chemical precipitation, filtration, oxidation, ion exchange treatment and adsorption have been proposed for the purification of contaminated water. Among these methods, adsorption has taken an important position in water purification technology. This is because of its ease of operations, cost-effective maintenance, and availability of adsorbents in various forms with high surface area, porous structure and specific surface reactivity. Instead of having many attractive properties, many adsorbents have failed to achieve a good acceptability at commercial levels. In the recent years, nanotechnology approaches have introduced nanoadsorbent which is capable of removing water pollutants more efficiently. In this review, various water treatment techniques with their shortcomings followed by efficiency of adsorption and nanoadsorbent for pollutant removal are discussed with green chemistry perspectives.
Chemical and Thermal Stability of Multiple Ions Doped Non-Stoichiometric Nanoapatite Heat-Treated in CO2 and Air Atmospheres
Authors: Thevi K. Jamuna , Kadir Mohammed Rafiq Abdul , Hermawan Hendra
Published: April 2014

Nanostructured apatite has been widely used as a bone substitute material due to its close resemblance to human bone mineral. To further mimic biological apatites, multiple ions doped non-stoichiometric nanoapatite has been studied. A nanosized apatite (NAp-2) containing Mg (1.09 wt%), Na (0.15 wt%), K (0.008 wt%) and CO32- (5.18 wt%) was synthesized by a wet precipitation technique. The presence of these ions in NAp-2 was detected using ICP. Broad diffraction peaks of XRD results indicated the presence of nanocrystalline phase pure NAp-2. The primary particle size of the resulted powder was ~ 20 nm, typical of bone crystal size, estimated using Scherrers equation. Based on CHN results, the NAp-2 powders showed a total loss of 51 and 78% of carbonate ions when heat-treated at 900°C in both CO2 and air atmospheres, respectively. This indicates that the heat-treatment in CO2 flux has reduced the carbonate ions lost from the NAp-2. A highly crystalline HA phase was formed in the ionic doped NAp-2 without secondary phases, indicating a thermal stability of this powder at 900°C in CO2 and air atmospheres. Thus, this study demonstrated that a phase pure multiple ions doped nanoapatite was synthesized using a wet precipitation technique.
Chemical Bath Temperature Investigation for Electroless Nickel Immersion Gold
Authors: Retnasamy Vithyacharan , Sauli Zaliman , Hashim Uda , Yeow Aaron Koay Terr , Taniselass Steven , Ayub Ramzan Mat
Published: April 2014

Conventional gold wire bonding to alunimium bond pads leads to the formation of intermetallic compound. Electroless Nickel Immersion Gold (ENIG) has been proposed as surface finish for aluminium bond pads to improve high temperature reliability. In order to create acceptable solder bumps prior to reflow process, a particular bump height for ENIG bumps need to be obtained. This paper reports the effects of chemical bath temperature in response to the bump height using a shorter process time. Analysis was done by using a design of experiment (DOE). The results suggest that higher temperature increases the bump height. Electroless nickel temperature has more influence to the bump height compared to immersion gold temperature.
Low-Temperature Synthesis of Cordierite Using Magnesite
Authors: Pee Jae Hwan , Kim Geun Hee , Lee Na Ri , Kim Hyung Tea , Punsukumtana Lada
Published: April 2014

Cordierite (2MgO·2Al2O3·5SiO2) has a low density of 2.2 g/cm3due to its high magnesium content. Because of its low thermal expansion coefficient of 1~2 x10-6/°C, many studies are being conducted on the synthesis of cordierite with the expensive petalite as a replacement for lithium alumina silicate-based heat-resistant materials. The cordierite can be synthesized over a wide range: SiO2at 50~70%, Al2O3at 20~40%, and MgO at 10~30%. In this study, the range of chemical composition and temperature of cordierite synthesis is thoroughly investigated. In particular, we use natural materials (magnesite, kaolin and clay) to examine how thermal properties are affected by changes in crystal phase arising from the varying composition of MgO, SiO2and Al2O3.We focused on factors leading to an increase in the rate of cordierite synthesis at temperatures below 1280°C. From observing the synthetic rate over 1250~1280°C, the sintered body at 1280°C had a high synthetic rate greater than 80%. Magnesite was ball milled at constant intervals, and mean particle size was controlled to improve the synthetic rate of cordierite. As a result, the cordierite synthetic rate increased by more than 15% with decreasing the mean particle size of magnesite.
Metakaolin-Based Porous Geopolymer with Aluminium Powder
Authors: Keawpapasson Pimpawee , Tippayasam Chayanee , Ruangjan Silawat , Thavorniti Pajaree , Panyathanmaporn Thammarat , Fontaine Alexandre , Leonelli Cristina , Chaysuwan Duangrudee
Published: April 2014

Porous concretes such as aerated and lightweight concretes are commonly used in construction fields. Lightweight construction materials are used to reduce either the weight or the budget of building structures. Porous concrete production is widely utilised aluminium (Al) powder to increase pores in concrete structures and giving information for porous geopolymer production. It was introduced by adding 0.05-1% Al-powder as the initiated materials of geopolymers, to react with water in those materials and promote hydrogen gas inside specimens. The research, therefore, focused on the synthesis of porous geopolymer by metakaolin as a pozzolan and mixed with alkali solution (8M NaOH and Na2SiO3) as well as Al-powder as a foaming agent. The highly porous geopolymers were produced with various Al-powders as 0%, 0.2%, 0.4%, 0.6% 0.8% and 1% by weight. After 7, 14 and 28 days age, the specimens were tested the mechanical properties, such as compressive and flexural strengths. The water absorption, apparent porosity and bulk density were analyzed at 28 days age. The synthesis of metakaolin-based porous geopolymers with Al-powder presented good results. It showed that Al-powder content affected to degree of porosity of geopolymers. Keywords: Metakaolin based geopolymer, Porous geopolymer, Aluminium powder, Foaming agent, Mechanical and physical properties
Study of Residual Stresses in Traditional Ceramics
Authors: Venturelli C. , Paganelli Mariano
Published: April 2014

Residual stresses in traditional ceramics may have different origin and nature. In glazed tiles (both porous and sintered), they can be due to the thermal expansion mismatch of glaze and body. Another type of residual stresses in glazed and unglazed porcelain tiles is due to temperature gradients during cooling, which give rise to volume variations in different areas of the same ceramic ware. Thermal gradients may originate not only between the surface and the core of the tile, but also between the upper and the lower face of the tile. The common practice in the porcelain tile industry to use differential cooling to control the planarity of the finished product induces permanent changes of volume in different areas of the ceramic ware, which give rise to permanent states of stress. At room temperature there are two main stress relaxation mechanisms, depending on the nature of the tiles: cracks growth in porcelain tiles and post-expansion in porous tiles. Generally, residual stresses relaxation cause delayed curvature according to these different mechanisms. Optical dilatometry and optical fleximetry techniques allow to investigate the volume changes induced by the cooling rate and the glaze-body coupling, factors responsible for residual stresses.
Influence of N-Doped TiO2 Nanocomposite Film on Hydrophilic Property of Rubber Dipping Former Surface
Authors: Masae Mahamasuhaimi , Sikong Lek , Kooptarnond Kalayanee , Taweepreda Wirach , Saito Fumio , Pitsuwan Pichaya
Published: April 2014

The objective of this study is to explore a method to improve hydrophilicity of the surface of formers that could be more easily dipped to produce high quality dipped rubber products. Photocatalytic TiO2 composite films were prepared by sol-gel method. Glass formers were coated with nitrogen doped TiO2 nanocomposite film by dipping method and annealed at 600°C for 1 h. Phase formation of TiO2 was characterized by XRD. Morphology of the TiO2 films was observed by using atomic force microscopy (AFM). Optical absorption of the films and degradation concentration of methylene blue had been measured employing UV-Vis spectrophotometer. The hydrophilicity of the thin films was determined in terms of the contact angles of water and NR rubber latex droplets on the coated TiO2 composite films under visible light irradiation. It was found from the experimental study that the TiO2 nano-composite film can improve wet-ability of the coated former surfaces.
Microwave-Assisted Hydrothermal Synthesis and Photocatalytic Properties of Cr and La-Codoped SrTiO3 Photocatalyst
Authors: Akita Ryusuke , Dong Qiang , Yin Shu , Sato Tsugio
Published: April 2014

Cr and La-codoped SrTiO3nanoparticles were successfully prepared by a microwave-assisted hydrothermal synthesis. The products were characterized by XRD, TEM, BET specific surface area, and UV-Vis absorption spectra. The photocatalytic activity was determined by deNOxability under irradiation of a 450 W high-pressure mercury lamp. The products could absorb the visible light and showed high photocatalytic ability for the decomposition of NOxgas. All samples showed the photocatalytic activities superior to that of commercial titania (Degussa P25) in both UV and visible light regions.
Morphology Controlled Flower-Like ZnO Particles Synthesized by Low Cost High Pressure Cooker
Authors: Sooksaen Pat , Rapp Malin , Sirinakorn Thipwipa , Meepanya Phatthraporn , Leangthammarat Pawanan
Published: April 2014

ZnO is a good candidate material for many optical and optoelectronic applications. ZnO with various shapes and sizes can be prepared via chemical methods such as precipitation, microwave heating and hydrothermal method. Generally ZnO synthesized by hydrothermal method uses autoclave which is expensive and gives low % yield. This research applied a low cost high pressure cooker which replaced the use autoclave to synthesize ZnO as its concept is similar to hydrothermal method. In this study, it was found that the size and shape of the synthesized ZnO particles were affected by several factors such as Zn2+/OH- ratio, temperature and time. Zinc nitrate hexahydrate, Zn(NO3)2.6H2O and sodium hydroxide, NaOH were used as metal ion sources in the precursor solutions. Structural and morphological studies were performed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The effect of Zn2+/OH- ion ratios, hydrothermal temperature and time on the size and morphology of ZnO were discussed in detail. All the synthesized conditions yielded hexagonal wurtzite structure of ZnO confirmed by XRD, without calcinations process. SEM images showed plate-like structure for Zn2+/OH- ratio = 1:7.5 and 1:15 and flower structure for Zn2+/OH- ratio = 1:20. Sizes of the synthesized ZnO particles decreased with increasing hydrothermal temperature from 120to 200°C. The longer the synthesized time period the larger the ZnO particles obtained.
Influence of Specimen Dimensions and Temperature on the Debinding Behavior of Alumina Feedstock
Authors: Chomsirigul Nawamin , Khuanthong Onwadee , Sooksaen Pat , Chuankrerkkul Nutthita
Published: April 2014

This work investigated the influence of specimen dimensions and temperature on the debinding behavior of alumina feedstock for powder injection process. Polyethylene glycol (PEG) was used as a based binder. It is soluble in water therefore the use of wax-based binder system can be avoided. PEGs with a molecular weight of 1500 and 4000 were mixed with polyvinyl butyral (PVB) a minor component. Stearic acid was added during feedstock preparation to act as a lubricant. Debinding process was carried out using a water leaching test at 30 and 70 °C to study for PEG removal rate. Specimens retained their shapes after leaching of the binders. In general, the rate of binder removal increased at initial stage then slowed down at longer leaching times. A faster debinding rate was achieved at 70 °C when compared to 30 °C. In addition, samples with a higher surface area to volume ratio (As/V) led to an increase in the %PEG removal rate. This study also showed the relationship between %PEG removal as a function of different surface area to volume ratio (As/V) which can be helpful in predicting %PEG removal for any other samples having cylindrical shape.
A Study of Alumina Spray Dried Granules on Packing Density and Sintering Shrinkage of Simple and Complex Shape
Authors: Somton Kritkaew , Dateraksa Kannigar , McCuiston Ryan C.
Published: April 2014

The relationship between granule property, pressed green density and shrinkage of 92% alumina spray dried granules were studied for both simple and complex shapes. Two types of granules, the in-house granule (A) and the commercial granule (B), was observed morphology using microscopy and liquid immersion techniques. Examination of the granules showed that granule A have several undesirable features; agglomeration, hollow granules and non-spherical granules where granule B showed them to be unagglomerated and spherical. The mixture A and B were conducted to study the particle size distribution (PSD) and compared with Dinger-Funks ideal PSD. The result showed that granule mixture A: B 100:0 had closest PSD curve fitted but had lowest tapping and pressed green density than 70:30 and 30:70 mixtures. This is because the agglomerated shape in granule mixture 100:0 caused air gap in between granule contact resulting in low tap density. The specific fracture strengths of the granules can affect to the densification of green ceramic during pressing. Low pressed green density affected to a high amount of shrinkage during sintering and leading to small grain growth after sintered. The simple and complex shape follows the same trend in shrinkage.
Effect of Sintering Conditions on Mechanical and Optical Properties of 3Y-TZP Dental Ceramic
Authors: Dateraksa Kannigar , Ngernbamrung Sukunthakan , McCuiston Ryan C.
Published: April 2014

The use of zirconia dental ceramics has grown in recent years due to improvements in esthetics and biocompatibility. Zirconia is used in dental applications for its high strength and fracture toughness. In this research, the influence of sintering conditions on the strength and optical properties of zirconia was investigated. Spray dried granules of 3Y-TZP zirconia were die pressed into disc-shaped samples and cold isostatic pressed at 250 MPa. Sintering was conducted using either one step sintering at 1500 oC or two-step sintering, with pre-sintering at 1200 oC and final sintering at 1500 oC. Heating rates of 2 and 10 oC/min were used. The biaxial flexural strength, fracture toughness, density, microstructural characteristics and optical properties of the sintered samples were determined. It was found that the sintering conditions did appear to influence the mechanical and optical properties. The sintering conditions had no significant effect on the density. It was concluded that for the sintering conditions examined, the two-step sintering with a heating rate of 2 oC/min produced the best average mechanical and optical properties of 3Y-TZP zirconia.
Effect of MnCO3 Doping on Microstructure and Electrical Properties of PSZT Ceramics
Authors: Boonruang Arjin , Ngernchuklin Piyalak , Daungdaw Saengdoen , Yongpraderm Nestchanok , Eamchotchawalit Chutima
Published: April 2014

The effect of manganese doping on microstructure, piezoelectric and electromechanical properties of Pb0.94Sr0.06(Zr0.52Ti0.48)O3 (PSZT) ceramics has studied. The PSZT ceramics doped MnCO3 concentration in the region of 0-1.0 mol% were prepared by a solid-state reaction and conventional sintering process. Phase identification showed the formation of single phase perovskite structure in all compositions. Microstructure and fracture behavior were observed by scanning electron microscopy (SEM). The fracture behavior demonstrated the change of fracture type from trangranular to mix of trans-and inter-granular type with increasing the amount of MnCO3. Dielectric constant (K), d33 and kp were increased when higher amount of MnCO3 was doped. In addition, the mechanical quality factor (Qm) was highest at 0.1 mol% MnCO3 doping in PSZT ceramics.
Anodic Oxide Film Formed on Ti-6Al-4V at a Low Current Density in Monocalciumphosphate Monohydrate (MCPM) Electrolyte and its Biocompatibility
Authors: Sriprasertsuk Sutthima , Whangdee Phanawan , Jinawath Supatra , Thunyakitpisal Pasutha , Kashima Dujreutai Pongkao
Published: April 2014

Anodic oxide film on titanium alloy (Ti-6Al-4V) substrate was prepared by anodization. The reaction was done by applying low current densities from 0.25 to 2 mA/cm2 for 30 minutes using monocalciumphosphate monohydrate (MCPM) solution as an electrolyte. Essential parameters which affected to the formation of anodic oxide film were studied. The properties of the anodic oxide film would be optimized when the parameters were appropriately controlled. Increasing of the current density and the concentration of MCPM electrolyte could promote hydrophilicity and surface roughness of the film. After anodization, the anodic oxide film formed at 2 mA/cm2 in 1M MCPM showed the best hydrophilicity (lowest water contact angle) and the film formed at 0.25 mA/cm2 in 0.5M MCPM showed the lowest hydrophilicity (highest water contact angle). XPS analyses confirmed that the chemical species of as-anodized film formed at 2 mA/cm2 in 1M MCPM changed. Ti2p spectra scarcely changed while the O1s spectra significantly changed due to the presence of chemisorbed water and Ti-OH formed during anodization. The SEM micrographs also revealed the biocompatibility from the growth of the cementoblast cell on anodized surface. It was indicated that anodization using MCPM as an electrolyte at 2 mA/cm2 in 1M MCPM could modify the surface roughness and chemical species and that both are likely to be crucial key factors for enhancing of hydrophilicity of as-anodized film which would enhance the biocompatibility of Ti-6Al-4V as a result.
Role of Tungsten Carbide Reinforcement on Alumina Matrix Composites Fabricated by Powder Injection Moulding
Authors: Chuankrerkkul Nutthita , Buggakupta Wantanee , Surawatthana Juthathep
Published: April 2014

In this work, properties of tungsten carbide (WC) particulate reinforced alumina matrix composites fabricated by powder injection moulding (PIM) technology were reported. The 90 wt% of Al2O3 and 10 wt% of WC powders were mixed with a composite binder, composed of 85 wt% polyethylene glycol (PEG) and 15 wt% polyvinyl butyral (PVB). Feedstocks of alumina and alumina-tungsten carbide composites having powder loading from 44 to 52 vol% were prepared and injected into a mould of rectangular shape. The binders in the mouldings were leached by water and then thermally debinded prior to sintering at 1600 °C for 2 hours in argon atmosphere. Strength, Density, hardness and density of the alumina and alumina composites’ bodies were compared and reported. It was found that the properties of sintered specimens, both Al2O3 and Al2O3/WC composites, increased with increasing powder loadings. The properties enhancement was also presented in the WC reinforced alumina composites. The composite of 52 vol% powder loading had flexural strength and hardness of 253.8 MPa and 12.5 GPa, respectively.
Fabrication of Silicon Carbide from Rice Husk by Carbothermal-Reduction and In Situ Reaction Bonding Technique
Authors: Makornpan Chalermkwan , Mongkolkachit Charusporn , Wanakitti Suda , Wasanapiarnpong Thanakorn
Published: April 2014

Silicon carbide (SiC) ceramics were prepared by carbothermal reduction together with in-situ reaction bonding. Raw rice husk was carbonized in an incineration furnace. The carbonized rice husk was ground and was then treated with hydrochloric acid by varying concentrations. The sample powders were mixed with silicon metal powder and pyrolyzed at various temperatures in either argon or nitrogen atmosphere. Silicon carbide phase was found in all pyrolyzed samples. Cristobalite was found in argon atmosphere pyrolyzed samples while silicon oxynitride was found in the samples pyrolyzed in nitrogen atmosphere at lower than 1500 °C. Silicon carbide whisker is the main phase on the surface of pyrolyzed sample. Increasing pyrolysis temperatures decreased the amount and size of silicon carbide whisker but increased the silicon carbide particle. Porosity and weight loss of samples after pyrolysis were increased with increasing temperatures due to the reaction in the system.
Effect of Sintering Parameters and Ta2O5 Doping on the Microstructure and Dielectric Properties of BaTiO3 Based Ceramics
Authors: Islam Md. Fakhrul , Mahbub Rubayyat , Mousharraf Adnan
Published: April 2014

The main focus of the research was to correlate the composition and sintering parameters with the microstructure and dielectric properties of Ta2O5 (Tantalum Oxide) doped BaTiO3 (Barium Titanate) ceramics. Ta2O5 was doped at three different percentages viz. 0.5, 1.0 and 1.5 mole%. The doped samples were then sintered using both single and double stage sintering techniques. Thereafter field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) techniques were used to examine the structure of the samples with particular focus on the incorporation of Ta5+ions into the BaTiO3 crystal lattice. Finally, the dielectric properties were analyzed using impedence analyzer and the relationship between the properties and structure of doped BaTiO3 was established. From the research, it can be stated that double stage sintering yielded best dielectric properties. The best stable value of room temperature dielectric constant (k) of 19000 was obtained for 1.5mole % Ta2O5 doped BaTiO3 sample, sintered at 1320°C for 0 hour and 1280°C for 6 hours due to the combination of high percent theoretical density (%TD) and optimum grain size. At a temperature range of 30°C to 60°C, this combination of composition and sintering parameters yielded dielectric constant in the range of 18000-19000.
Influence of the Laminate Configurations of Transparent Armor on its Ballistic Protection
Authors: Jantharat Priawthida , McCuiston Ryan C. , Gamonpilas Chaiwut , Kochawattana Sujarinee
Published: April 2014

The ballistic performance of transparent armors has been continuously developed for an application on security purposes. Generally, ballistic performance of the laminated glass increases with its thickness and weight while the user requirement prefers high level of ballistic protection with thin and light weight body. In this study, fabrication of light weight glass-PVB transparent armors with the level-3 protection according to the National Institute of Justice (NIJ) standard was attempted. The ballistic performances of various configurations of glass-PVB laminates were determined against 7.62 mm ammunitions. Results from fragmentation analysis indicated the influence of glass-sheet-arrangement in the armor structures on the ballistic damages. The minimum requirement on the thickness of front-face layer was also discussed. To verify the experimental results, finite element analysis was performed on all laminated systems. It was found that the results from computational analysis were in reasonable agreement with the experimental results.
Synthesis and Characterization of La4-xSrxNi3O10±δ Ruddlesden - Popper Structure
Authors: Chokkha Siriwan , Kuharuangrong Sutin
Published: April 2014

La4-xSrxNi3O10±δ (x = 0, 0.05, 0.1, 0.2, 0.3, 0.5 and 1) compositions synthesized via citrate gel method have been investigated as a candidate cathode for intermediate temperature SOFC. The n = 3 RP single phase of La4-xSrxNi3O10±δ (x = 0, 0.05, 0.1 and 0.2) can be achieved after calcined at 1000°C for 4 hrs in air. The further addition of Sr with x 0.3 leads to obtain La2-xSrxNiO4±δ and NiO as the second phase. La4Ni3O10±δ based material shows the highest electrical conductivity with a value of 124 S/cm at room temperature. With Sr dopant, both of transition temperature and the electrical conductivity of La4Ni3O10±δ decrease and further decrease with increasing the amount of Sr. The electrical conductivity at 250°C of La4-xSrxNi3O10±δ (x = 0, 0.05 and 0.1) is 100, 94 and 75 S/cm respectively. For x = 0.3, 0.5 and 1, it reduces to the values of 28, 7 and 4 S/cm, respectively because of the lower conductivity phase of La2-xSrxNiO4±δ.
Low Melting Glass Billets for Pot Furnace Glass Processing
Authors: Meechoowas Ekarat , Jampeerung Parida , Tapasa Kanit , Naknikham Usuma , Jitwatcharakomol Tepiwan
Published: April 2014

Soda-lime-silica glasses were prepared by the composition range of SiO267-72, Na2O+K2O 15-18, CaO+MgO 5-8, BaO 2-4 and ZnO 2 in wt% for producing low melting glass billets. The billet properties were similar to commercial glasses, but higher melting ability. Respecting to thermodynamic calculation approach, the exploited heat (Hex), which was the required heat for melting the batch from atmosphere temperature to the melting temperature, was calculated in order to compare the melting ability. The results represented that glass batches with lower silica content which possessed lowerHexthan batch with higher silica and consequently higher melting ability. Therefore, to reduce melting energy, silica content in batches should be as low as possible.Hexof batch with SiO267 wt% was 480 kWh/t, while the batch with SiO272 wt% was higher, namely 495 kWh/t. In addition, the glass batch with SiO267 wt% was completely melted at 1350°C only. Properties of billets were determined, and the coefficient of thermal expansion was 9.6 x 10-6°C-1. The glass transition point was 535 °C, and the refractive index was approximately 1.52. The study succeeded in producing glass billets with good quality and with melting temperatures lower than 1400°C.