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Search Results: 1 - 10 of 842 matches for " Othman Mamat "
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The Development and Characterization of Zirconia-Silica Sand Nanoparticles Composites  [PDF]
Tahir Ahmad, Othman Mamat
World Journal of Nano Science and Engineering (WJNSE) , 2011, DOI: 10.4236/wjnse.2011.11002
Abstract: The present study aims to develop zirconia-Silica sand nanoparticles composites through powder processing route and to study the physical properties, mechanical properties and microstructure of the composites. Zirconia based silica sand nanoparticles composite with 5, 10, 15 and 20 wt.% were developed through powder processing technique and sintered at 1500 ℃ for two hours. A decreasing trend of green density however an improvement in sintered density was observed. Also the addition of silica sand nanoparticles with 20 wt.% increased the hardness up to 12.45 GPa and microstructures indicated the diffusion mechanism of silica sand nanoparticles into pore sites of the composites.
Effect of Conduction Pre-heating in Au-Al Thermosonic Wire Bonding  [PDF]
Gurbinder Singh, Othman Mamat
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2011, DOI: 10.4236/jsemat.2011.13018
Abstract: This paper presents the recent study by investigating the vital responses of wire bonding with the application of conduction pre-heating. It is observed through literature reviews that, the effect of pre-heating has not been completely explored to enable the successful application of pre-heating during wire bonding. The aim of wire bonding is to form quality and reliable solid-state bonds to interconnect metals such as gold wires to metalized pads deposited on silicon integrated circuits. Typically, there are 3 main wire bonding techniques applied in the industry; Thermo-compression, Ultrasonic and Thermosonic. This experiment utilizes the most common and widely used platform which is thermosonic bonding. This technique is explored with the application of conduction pre-heating along with heat on the bonding site, ultrasonic energy and force on an Au-Al system. Sixteen groups of bonding conditions which include eight hundred data points of shear strength at various temperature settings were compared to establish the relationship between bonding strength and the application of conduction pre-heating. The results of this study will clearly indicate the effects of applied conduction pre-heating towards bonding strength which may further produce a robust wire bonding system.
Process Parameters Optimization of Silica Sand Nanoparticles Production Using Low Speed Ball Milling Method
Zulkhairi Rizlan,Othman Mamat
Chinese Journal of Engineering , 2014, DOI: 10.1155/2014/802459
Abstract: Experiments are designed using Taguchi method to find the optimum parameters for silica sand nanoparticles production using low speed ball milling. Orthogonal array and signal-to-noise ratio are applied to study performance characteristics of machining parameters which are the ball to powder weight ratio, volume of milling jar, and rotation speed. Results obtained from signal-to-noise ratio analysis showed that ball to powder weight ratio is the most influential parameter. 1. Introduction Nanoparticles of silica sand have been researched progressively and produced due to the unique features as a result of size reduction. Silica sand nanoparticles have proved to be a very effective additive to polymers by improving durability, strength, and flexibility. Nanosilica is also used as an additive to improve strength and workability of self-compacting and high performance concretes. Nanosilica particles are widely produced by chemical processes. However, chemical synthesis of nanosilica produces high contamination in the final products. As the demand is increasing for higher nanosilica purity, contamination is expected at the minimum level. Other than chemical synthesis, other processes such as precipitation, vaporization at high temperature, sol-gel process, high speed vertical rotating mill, and planetary ball mill are among the most commonly used methods to produce silica sand nanoparticles. The objective of this research is to design a technique of transforming natural Tronoh silica sand to silica sand nanoparticles by using a combination of low speed ball milling and heating processes. It is expected that the technique will be able to produce high purity silica sand nanoparticles of less than 100?nm consistently. Taguchi method provides a simple, efficient, and systematic approach to determine the optimum parameters [1]. Compared to the factorial method, instead of testing all possible combinations of parameters available, Taguchi method provides a more simplified way to set up the combination of experiment parameters. The parameters tested in this paper are ball to powder weight ratio (BPR), volume of milling jar, and milling speed. 2. Parameters Identification There are a lot of parameters used in ball milling process. However, the parameters that have been tested most for optimization are the rotation speed and milling time. This indicates that these two parameters play an important role in determining the effectiveness of the milling. As supported by Simoes, ball to powder weight ratio is recognized as one of the most influential parameters, alongside
First-Principles Calculations of the Structural, Mechanical and Thermodynamics Properties of Cubic Zirconia  [PDF]
Ibrahim D. Muhammad, Mokhtar Awang, Othman Mamat, Zilati Bt Shaari
World Journal of Nano Science and Engineering (WJNSE) , 2014, DOI: 10.4236/wjnse.2014.42013
The structural, mechanical and thermodynamics properties of cubic zirconium oxide (cZrO2) were investigated in this study using ab initio or first-principles calculations. Density functional theory was used to optimize the crystal structure of cZrO2 and thereafter, simulations were conducted to predict the lattice parameters and elastic constants. The Zr-O bond distance was calculated as 2.1763 Å with unit cell density of 6.4179 g/cm3. The data obtained were used to determine Young’s modulus, bulk modulus, Poisson’s ratio and hardness of cZrO2 as 545.12 GPa, 136.464 GPa, 0.1898 and 12.663(Hv) respectively. The result indicates that cZrO2 is mechanically stable with thermodynamics properties of a refractory material having potential for structural and catalytic applications in various forms as a nanomaterial.
A Review of Effects of Molding Methods, Mold Thickness and Other Processing Parameters on Fiber Orientation in Polymer Composites
Ahmed N. Oumer,Othman Mamat
Asian Journal of Scientific Research , 2013,
Abstract: In injection molded fiber reinforced composites, the mechanical and physical properties of the final product are highly dependent on the patterns of fibers alignment. The orientation of the fibers can be influenced by many factors such as molding methods, materials used, geometry of the part and other processing parameters. Thus, there is considerable interest in studying the factors that affect the fiber orientation, hence the properties of the final product. This study presented a general review on the effects of these factors on fiber orientation in injection molded fiber-reinforced polymer composites. The fiber orientation of a part made by conventional injection molding is compared with those produced by injection-compression and push-pull injection techniques. Effects of injection speed, type of flow and mold thickness on fiber orientation are also discussed. Hence, this review could assist in decisions regarding the design of composite products.
Reaction Layers of the Diffusion-Bonded Sialon and High-Chromium Steel
Hudiyo Firmanto,Patthi Hussain,Othman Mamat
Journal of Applied Sciences , 2011,
Abstract: This study investigates diffusion bonding of sialon and high-chromium steel. Sialon and 7.5%-Cr steel were directly joined. The process was performed using hot press machine. Good joint was achieved due to the reaction of the sialon and the steel. The elemental inter-diffusion developed reaction layers in the interface of the bonded materials. The layers consisted of a thin and porous layer adjacent to the sialon and a thicker diffusion zone extended into the steel. Precipitates as reaction products of the sialon and the steel were found in the reaction layer in the sialon side. The reaction layers were more ductile then the bonded materials and helped to attain the joint.
Studying the Effects of Adding Silica Sand Nanoparticles on Epoxy Based Composites
Tahir Ahmad,Othman Mamat,Rafiq Ahmad
Journal of Nanoparticles , 2013, DOI: 10.1155/2013/603069
Abstract: The research about the preparation of submicron inorganic particles, once conducted in the past decade, is now leading to prepare polymer matrix composite (PMC) reinforced with nanofillers. The objective of present research is to study the modified effects of reinforcement dispersion of nanoparticle silica in epoxy resin on the physical properties, mechanical and thermal behaviour, and the microstructure of resultant composites. Stirrer mixing associated with manual mixing of silica sand nanoparticles (developed in our earlier research) (Ahmad and Mamat, 2012) into epoxy was followed by curing being the adopted technique to develop the subject nanocomposites. Experimental values showed that 15?wt.% addition of silica sand nanoparticles improves Young’s modulus of the composites; however, a reduction in tensile strength was also observed. Number of holes and cavities produced due to improper mixing turn out to be the main cause of effected mechanical properties. Addition of silica sand nanoparticles causes a reduction in degree of crystallinity of the nanocomposites as being observed in differential scanning calorimetry (DSC) analysis. 1. Introduction Nowadays industrial and academic research laboratories are focusing much of their efforts to develop and improve physical, mechanical, and electrical properties of polymer nanocomposites. Their interest to develop such composites is mainly because of the fact that nanoparticles present a high surface-to-volume ratio which may induct unique properties to these nanocomposites as compared to macro-scale composites [1]. Andritsch et al. [2] prepared nanocomposites filled with SiO2, Al2O3, and AIN with an average particles size from 22?nm to 10?nm and studied the nanoparticles dispersion and DC breakdown strength. They observed the highest DC breakdown strength for 0.5?wt.% for two component system. It was also noticed that the DC breakdown strength increased with 10?wt.% as compared to 2 and 5?wt.% and again decreased with 15?wt.% nano-fillers. Yasmin et al. [3] studied the dispersion of clay nanoparticles in epoxy-based composites using a three roll mill with the concentration of 1–10?wt.%. This technique was found highly efficient and environmentally friendly due to excellent dispersion of nanoparticles within a short time. Elastic modulus was improved up to 80% with 10?wt.% addition of clay nanoparticles in epoxy. Absence of any improvement in tensile strength of the nanocomposites over pure epoxy was due to the clustering of nanoparticles and/or to the occasional occurrence of nano- to microsize voids in
A Direct Comparison of Processing Methods of High Purity Rice Husk Silica
Benjamin Iyenagbe Ugheoke,Othman Mamat,B. Ari-Wahjoedi
Asian Journal of Scientific Research , 2013,
Abstract: It is an established fact that rice husk is rich in amorphous silica which when extracted in sufficiently pure form, could be used in several industrial applications and in the manufacture of value added products. Many of the processes employed for the purification of rice husk silica involve the use of strong acid and bases, requiring complex unit operations and extended times, apart from their unfriendliness to environment and personnel. The hydro thermobaric process was developed as a viable alternative to these rice husk silica purification processes. This study reported a performance comparison in terms of product purity, yield, structure and processing time between the newly developed hydro thermobaric and other previously used processes. The new process surpasses others in terms of processing time and yield while being at par with them in terms of product quality and structure.
Surfactant-decorated graphite nanoplatelets (GNPs) reinforced aluminum nanocomposites: sintering effects on hardness and wear
Zeeshan Baig,Othman Mamat,Mazli Mustapha,Asad Mumtaz,Sadaqat Ali,Mansoor Sarfraz
- , 2018, DOI: https://doi.org/10.1007/s12613-018-1618-3
Abstract: The exceptional properties of graphene make it ideal as a reinforcement to enhance the properties of aluminum matrices and this critically depends on uniform dispersion. In this study, the dispersion issue was addressed by sonication and non-covalent surface functionalization of graphite nanoplatelets (GNPs) using two types of surfactant: anionic (sodium dodecyl benzene sulfate (SDBS)) and non-ionic polymeric (ethyl cellulose (EC)). After colloidal mixing with Al powder, consolidation was performed at two sintering temperatures (550 and 620°C). The structure, density, mechanical and wear properties of the nanocomposite samples were investigated and compared with a pure Al and a pure GNPs/Al nanocomposite sample. Noticeably, EC-based 0.5wt% GNPs/Al samples showed the highest increment of 31% increase in hardness with reduced wear rate of 98.25% at 620°C, while a 22% increase in hardness with reduced wear rate of 96.98% at 550°C was observed, as compared to pure Al. Microstructural analysis and the overall results validate the use of EC-based GNPs/Al nanocomposites as they performed better than pure Al and pure GNPs/Al nanocomposite at both sintering temperatures.
Mamat Rahmat
Bumi Lestari , 2010,
Abstract: Forest has an opponent function in climate change issue, as carbon sink and carbon source. Reducing emission from deforestation and forest degradation (REDD) is the mechanism to tackle green house gas emission from forest sector. The economic analysis of those projects in Indonesia has not conducted yet, moreover the benefit and cost analysis of REDD on forest management unit. The research was conducted in the unique site, at Industrial Forest Plantation PT. SBA WI, South Sumatera. Benefit and cost analysis and break-even cost analysis were conducted to evaluate project feasibility. The research result shows that forest management was not feasible if the role of the project aimed to product wood or reducing emission only which conducted in mutual. If the project aims to reach both roles together, it is very attractive. Break-even cost of reducing emission and carbon sequestration in PT. SBA WI Rp.29.000,- per ton CO2e equal to US$3,17. It was lower than the cost in Bolivia, Ghana, and Nepal and also cheaper than carbon price in voluntary market.
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