The aluminium-silicon (Al-Si) based on Metal Matrix Composites (MMCs) is widely used in lightweight
constructions and transport applications requiring a combination of high strength and ductility. A grain
refinement plays a crucial role in improving characteristics and properties of Al alloys. In this investigation,
titanium diboride (TiB2) and scandium (Sc) inoculants were added to the Al-Si alloys for grain refinement of
an alloy. In this investigation, the corrosion resistance rate of Al-Si cast alloy reinforced by TiB2 and Sc were
measured by potentiostat (AUTOLAB) instrument. The aim of this research is to investigate the corrosion
rate for Al-Si-TiB2-Sc composites that immersed in different concentration of acidic solutions. Besides, the
immersion time of acidic solutions also was investigated. All the samples were prepared accordingly for
ASTM standard by the composition of 6.0 wt% TiB2 and 0.6wt% Sc. All the samples undergo cold mounting
technique for easy handling on corrosion tests. Then the samples were immersed in two different
concentrations acidic medium solutions, which were 0.1.and 1.0 M hydrochloric acids (HCl). The corrosion
rate also was investigated for immersion samples of 1.0 M HCl for 21 days. From the results obtained, added
TiB2 and Sc onto Al-Si alloy gave the better properties in corrosion resistance. Corrosion rates to reduce when
the samples were immersed in a lower concentration of acidic medium, 0.1 HCl. However, there are some
significant on the result but it still following the corrosion rates trend. Thus, improvements to reinforcement
content need to be done in further research to cover the lack of this corrosion rates trend.
his paper presents the structure and static model of engine camshaft analysis. For the purposes of this analysis, the finite element method is used. Camshaft is one of the critical components for effective and precise work of internal combustion engines. This camshaft rotates at high speed causing pressure and vibration in the system. Camshafts are also subject to varying fatigue burden due to cam plunger contact. These precise values are required to be determined to prevent failure in the camshaft. The objective of the project is to model and to perform pressure analysis on the camshaft machine. In this project the standard engine cam shafts are modeled and analyzed using the CATIA V5R21 software respectively. This model is created by the basic requirements of the engine. It is done with an existing background, such as the power of acting on cam by means of a valve while running at maxi mum speed. Here the approach becomes fully CAE based. CAE - based approaches enrich Research and limit the time span. A study was conducted to predict the behavior of the different camshafts structure of the material using the finite three - dimensional pressure of the element. Four types of materials such as Steel, Titanium, Aluminum and Magnesium are taken into account. FEA Stress and maximum displacement decisions are calculated and compared to all of the above materials. The conclusion is to focus on the material suitable for the camshaft to reduce the maximum displacement and weight. Titanium materials become the best material for camshaft manufacturing based on analysis.
In the present research, aluminum oxide- water (Al2O3-H2O) nanofluid free convection due to magnetic forces through a permeable cubic domain with ellipse shaped obstacle has been reported. Lattice Boltzmann approach is involved to depict the impacts of magnetic, buoyancy forces and permeability on nanoparticles migration. To predict properties of Al2O3- water nanofluid, Brownian motion impact has been involved. Outcomes revels that considering higher magnetic forces results in greater conduction mechanism. Permeability can enhance the temperature gradient.
In this work, Sr0.3Ba0.4Pb0.3Fe12O19/(CuFe₂O₄)x (x = 2, 3, 4, and 5) as strongly exchange-coupled nanosized ferrites were fabricated using a one-pot sol⁻gel combustion method (citrate sol-gel method). The X-ray diffraction (XRD) powder patterns of the products confirmed the occurrence of pure, exchange-coupled ferrites. Frequency dependencies of the microwave characteristics (MW) were investigated using a co-axial method. The non-linear behavior of the MW with the composition transformation may be due to different degrees of Fe ion oxidation on the spinel/hexaferrite grain boundaries and strong exchange coupling during the hard and soft phases.
Gallium Nitride (GaN) is considered as the second most popular semiconductor material in industry after silicon. This is due to its wide applications encompassing Light Emitting Diode (LED) and power electronics. In addition, its piezoelectric properties are fascinating to be explored as electromechanical material for the development of diverse microelectromechanical systems (MEMS) application. In this article, we conducted a theoretical study concerning surface mode propagation, especially Rayleigh and Sezawa mode in the layered GaN/sapphire structure with the presence of various guiding layers. It is demonstrated that the increase in thickness of guiding layer will decrease the phase velocities of surface mode depending on the material properties of the layer. In addition, the Q-factor value indicating the resonance properties of surface mode appeared to be affected with the presence of fluid domain, particularly in the Rayleigh mode. Meanwhile, the peak for Sezawa mode shows the highest Q factor and is not altered by the presence of fluid. Based on these theoretical results using the finite element method, it could contribute to the development of a GaN-based device to generate surface acoustic wave, especially in Sezawa mode which could be useful in acoustophoresis, lab on-chip and microfluidics applications.
An integrated geophysical study was conducted to investigate the subsurface regional structure and the presence of a Quaternary sedimentary basin in the Olak Lempit - Banting area of Selangor, Malaysia. A regional gravity survey and the high resolution reflection seismic were employed to determine the thickness and areal distribution of the alluvial sedimentary basin as well as to investigate the depth and topography of the bedrock in the study area. The sedimentary basin hosts one of the most important coastal alluvial aquifer which was used to cater the shortage of domestic water supply during the worst water crisis that hit the state of Selangor in 1998. The surface geological map shows that in general 70% of the study area is covered by Quaternary deposits of Beruas, Gula and Simpang Formations which overlie the sedimentary bedrock of Kenny Hill Formation. The Beruas Formation consists of mainly clay, sandy clay and peat of Holocene fluviatile-estuarine deposits, whereas the Gula Formation represents Holocene marine to estuarine sediments which mostly consists of clay and minor sand. The Simpang Formation (Pleistocene) is a continental deposit comprising of gravel, sand, clay and silt. The underlying Kenny Hill Formation consists of a monotonous sequence of interbedded shales, mudstones and sandstones. The rock is Carbonaceous in age and it forms an undulating surface topography in the eastern part of the study area. A total of 121 gravity stations were established using a La Coste & Romberg gravity meter and the elevations of most of the stations were determined barometrically using Tiernan-Wallace altimeters. The high resolution seismic reflection using the common mid point (CMP) or roll along technique was carried out using a 24 channel signal enhancement seismograph and high frequency geophones. A total length of about 1.7 km stacked seismic section has been acquired in this survey and a nearby borehole data was used for interpretation. A relative Bouguer anomaly map shows an elongated zone of low gravity anomaly trending approximately NW-SE which is interpreted to be the deposition center of the Quaternary basin. The interpreted gravity profiles running across the central area of the study area show that the basin has thickness varies from tenth to several hundred meters with maximum depth to bedrock of about 275m. A gravity profile which passes through the eastern edge of the basin was modeled with depth to bedrock of about 178m below ground which agrees very well with those obtained from the interpreted seicmic section and borehole data. The stacked seismic section shows several high amplitude parallel to sub-parallel reflection overlying discontinuos and low reflection pattern. Reflections on the eastern part of the section is much shallower than the one observed on the western part which clearly indicates the presence of basinal structure with a total interpreted depth to bedrock of about 200 meters.
Nitridation behaviour of Al-Mg-Si alloys was studied as a function of temperature by means of thermogravimetry method. A reactive gas, N2-4%H2 at a rate of 10 ml/min was purged into the thermogravimetry analyser chamber. The Al alloys were heated from 25oC to 625oC at the heating rate of 15oC/min and then reduced to 3oC/min until it reached 1500oC. It was found that by varying the amount of Mg and Si in Al-Mg-Si alloys significantly influenced the growth of the composites. A differential thermogravimetric curve shows the Mg containing alloys experienced many steps of chemical reactions. This indicates that besides AlN presence as a major phase, other compounds also exist in the final product. The X-ray diffraction results confirmed the existence of oxide phases such as a-Al2O3, MgAl2O4 and MgO in addition to residual Si and Al metal. The presence of oxide compounds is believed to be due to the reaction between the alloying elements and residual oxygen gas left in the reaction atmosphere. It was also found that Si could play a role in promoting the weight gain of the composite produced. The heating rate has also a profound effect on the weight gain, whereby higher heating rate resulted in low yielded of AlN during the nitridation reaction of the Al-Mg-Si alloys.
Characterisation of the leaching behaviour of coal fly ash from Tenaga Nasional Berhad (TNB) by using tank leaching test method has been reported. The leachability of the constituents such as major elements and toxic metals in the coal fly ash was studied. Eight renewed leachant solutions after 6 hours, 1, 2, 5, 8, 21, 36 and 64 days were investigated after filtration. The parameters namely pH, cumulative release regarding the major elements and toxic metals to duration were presented. The results showed that the pH solutions increased from pH 4 to neutral and remained stable during the test. It might have resulted from the large buffering capacity of the coal fly ashes. Five major elements namely Al, Ca, K, Mg and Na were detected with Ca concentration in the leachant solutions was the highest for all samples. Toxic metals such as As, Ba, Co, Cr, Mn, Ni, Pb, Se and Zn were found and the test showed consistent results on the As, Ba, Mn, Se and Zn in leachant solutions. The findings also showed that some of the toxic metal concentrations namely As, Ba, Cr, Pb and Se exceeded the maximum allowance of the guideline of drinking water quality in Malaysia and WHO. Obviously, proper waste management has to be applied in this scenario.
Harmful algal blooms (HABs) events have been increasingly reported in the country, not only of the frequency and severity of the events, but also involved more species than previously known. In this paper, a decadal review of HABs events in Malaysia is summarized. Bloom events caused by harmful dinoflagellate species including the shellfish poisoning events were highlighted. Paralytic shellfish poisoning (PSP) is no longer restricted to Sabah coasts and Pyrodnium bahamense. Bloom of Alexandrium minutum was reported for the first time in the Peninsula with six persons hospitalized including one casualty after consuming the contaminated benthic clams. Algal blooms that are associated with incidence of massive fish kills have been reported from both east and west coasts of the Peninsula in conjunction to finfish mariculture loses. The culprits of these bloom events have been identified as the dinoflagellates, Cochlodinium polykrikoides, Neoceratium furca, Prorocentrum minimum, Noctiluca scintillans and a raphidophyte, Chatonella ovata. In this paper, some of these HABs species were characterized morphologically and genetically, including their toxicity. Therefore, with the increase of coastal utilization and eutrophication, prevention, management and mitigation strategies, such as site selection, moving pens, clay spraying should be adopted to minimize the impact of these natural events.
Anticorrosion potential of mangrove tannins on aluminium alloys AA6061 in NaCl solution has been studied using potentiodynamic polarisation method and scanning electron microscopy (SEM). The study was carried out in different pH of corrosive medium in the absence and presence of various concentrations of tannin. The corrosion inhibition behaviour of the mangrove tannin on AA6061 aluminium alloy corrosion was found to be dependant on the pH of NaCl solution. Our results showed that the inhibition efficiency increased with increasing tannins concentration in chloride solution at pH 6. Treatment of aluminium alloy 6061 with all concentrations of mangrove tannins reduced the current density, thus decreased the corrosion rate. Tannins behaved as mixed inhibitors at pH 6 and reduction in current density predominantly affected in cathodic reaction. Meanwhile, at pH 12, addition of tannins shifted the corrosion potential to more cathodic potentials and a passivating effect was observed in anodic potentials. SEM studies have shown that the addition of tannins in chloride solution at pH 12 reduced the surface degradation and the formation of pits.
The effect of adding aluminum hydroxide (ATH) in the palm-based polyurethane hybrid composite was studied. The compression stress and modulus, thermal conductivity and acoustic property were determined. The hybrid composite was prepared by adding 10 wt% of oil palm empty fruit bunch fibre (EFB) followed by ATH at varying amount of 2, 4 and 6 wt% of the overall mass of the resin. The compression stress and modulus gave the highest values of 575 kPa and 2301 kPa, respectively at 2 wt% ATH. At 4 wt% ATH, the compression stress and modulus decreased to 431 kPa and 1659 kPa, respectively and further decreased at 6 wt% ATH to 339 kPa and 1468 kPa respectively. The k-value increased with the increment of the ATH loading exhibited a poor thermal conductivity. Sound absorption analysis indicated that the absorption coefficient was higher at higher frequency (4000 Hz) for all samples with PU-EFB/ATH with 4% ATH showed the highest absorption coefficient.
Dihexyl-sexithiophene (DH6T) was doped with tris (8-hydroxyquinolinate) aluminum (Alq3) to prepare blends of DH6T/ Alq3 by dissolving the mixture in the chloroform/hexane co-solvent. Solid films with different thickness deposited on quartz substrates were obtained from the blends via casting process. Optical absorption spectroscopy has been performed to measure the optical band gap of pure and doped DH6T as well as variations in the band gap with dopant concentration (weight %). This variation in optical band gap with dopant concentration was determined quantitatively with fitted and extrapolated techniques and observed qualitatively from the red shift appeared along the optical absorption spectra. The results showed that within a specific dopant content, the optical energy gap, Eg of DH6T decreases from 2.69 eV to 1.8 eV with increasing dopant concentration to 23.1%.
In this work, the structural properties of radio frequency sputtering-grown zinc oxide (ZnO) thin films on sapphire (Al203), gallium arsenide (GaAs) and n-type silicon (Si) substrates were characterized. Scanning electron microscopy was employed to study the surface morphology of the samples. X-ray diffraction (xRD) measurements were also performed to obtain the structural information of the samples. The xRD results showed that the ZnO layers grown on different substrates have similar lattice constant (c) values, which were used to calculate the strain percentages of the ZnO thin films. The surface morphologies of the ZnO thin films indicated the formation of a granular surface when ZnO is deposited on n-type Si(100) and Si( 111 ) substrates. Meanwhile, a leaf-like surface is obtained when ZnO is deposited on GaAs and Al203 substrates. The results showed that the ZnO thin film grown on n-type Si(100) has the best quality among all the samples.
Industrial pollution issue and dark colour of carbon black, clay based non black filler are getting more importance for reinforcing elastomer. EPDM-Kaolin composites with various maleated EPDM concentration have been prepared by mixing on a two roll mill. The rheometry data showed the optimum cure time increases with increasing compatibilizer concentration without decreasing torque value indicating that acidic functional groups comes from compatibilizer could retard cure rate and increase the optimum cure time rather than change in the ultimate cure state. As the filler
concentration increases, the edge to edge and face to edge interaction between filler and EPDM increases and the free volume between EPDM molecules is reduced, the storage modulus increases. Moreover, the dynamic mechanical analysis also showed the increase in glass transition temperature with increase in filler concentration due to the inter-tubular diffusion of EPDM inside the clay. It was also observed that with increasing filler concentration, the resistivity and dielectric strength decreases and moreover with increasing compatibilizer concentration the resistivity decreases due to better dispersion of filler helps to build conduction path. The morphological study also revealed that homogeneity of filler dispersion increases with increase in compatibilizer concentration.
The main goal of this paper was to study the effect of ultrasonic treatment time on the mechanical properties of thermoplastic natural rubber(TPNR) reinforced with hybrid MWNTs-OMMT. The intercalation of TPNR enhancement into layers of clay by increasing the d-spacing was found using X-ray diffraction. The tensile properties of nanocomposites treated with ultrasonic increased when compared with untreated nanocomposites. The optimum ultrasonic treatment time was obtained at 3 h. The transmission electron microscope micrograph showed a combination of intercalated-exfoliated structure of the TPNR composites with organic clay and dispersion of MWNTs. The ultrasonic treatment can promote the dispersion of MWNTs-OMMT in TPNR and also improved the compatibility of hybrid filler and the TPNR matrix.
Three forest types were recognized at Chini watershed namely inland, seasonal flood and riverine forests. The soil physico-chemical characteristics from the three forest types were investigated to determine the soil properties variation within a landscape scale. Thirty sampling stations were established, represented by fourteen inland, nine stations in seasonal flood forest and seven in riverine forest. In each station, three soil samples were taken at 0-15 cm depth by using an auger. The study showed 71% of the soil in the inland forest was found to be dominated by clay, 44% of the soil in the seasonal flood forest by clay loam and 42% of the soil in the riverine forest was dominated by silty clay. The pH of all three types of forest studied was acidic and insignificantly different. Organic matter content in the study sites was moderate. The mean of electric conductivity (EC) and cation exchange capacity (CEC) values in the studied soils were low. Based on ANOVA, there were significant differences of the available P and K, K+, Ca2+ and Mg2+ cations and electrical conductivity amongst the three forest types (p<0.05). Cluster analysis showed that the variations of the soil physico-chemical characteristics between the three forest types were low thus indicating that the soil physico-chemical investigated in this study were not the only main contributing factors in floristic variation of the three forest types in Chini watershed.
The transition from monolayer to multilayer adsorption at the air-water interface in the presence of multivalent counterions has been demonstrated for a limited range of anionic surfactants which exhibit increased tolerance to precipitation in the presence of multivalent counterions. Understanding the role of molecular structure in determining the transition to surface ordering is an important aspect of the phenomenon. The focus of the paper is on the alkyl ester sulfonate, AES, surfactants; a promising group of anionic surfactants, with the potential for improved performance and biocompatibility. Neutron reflectivity measurements were made in aqueous solution and in the presence of NaCl, CaCl2, MgCl2 and AlCl3, for a range of alkyl ester sulfonate surfactants, in which the headgroup and alkyl chain geometries were manipulated. In the regions of monolayer adsorption changing the AES headgroup and alkyl chain geometries results in an increased saturation adsorption and in a more gradual decrease in the adsorption at low concentrations, consistent with a greater adsorption efficiency. Changing the AES headgroup and alkyl chain geometries also results in changes in the transition from monolayer adsorption to more ordered surface structures with the addition of AlCl3 and mixed multivalent electrolytes. A more limited surface layering is observed for the ethyl ester sulfonate, EES, with a C14 alkyl chain. Replacing the C14 alkyl chain with a C18 isostearic chain results in only monolayer adsorption. The results demonstrate the role and importance of the surfactant molecular structure in determining the nature of the surface adsorption in the presence of different electrolytes, and in the tendency to form extended surface multilayer structures.
The Sandakan Formation of the Segama Group is exposed across the Sandakan Peninsular in eastern Sabah. This Upper Miocene part of the Segama Group unconformably overlies the Garinono Formation and is conformably overlain by the Bongaya Formation. This formation was investigated with detailed logging of outcrops and microfossils analysis in order to map the depositional facies and sedimentary environment. This study showed the presence of seven lithofacies: Thick amalgamated sandstone; thin, lenticular interbedded HCS sandstones and mudstone; laminated mudstone with Rhizophora; trough cross-bedded sandstone; laminated mudstone; strip mudstone with thin sandstone and siltstone; and interbedded HCS sandstone and mudstone. Based on the presence of Rhizophora, Brownlowia, Florchuetia sp., Polypodium, Stenochleana palustris, Ascidian spicule low angle cross bedding, very fine grained sandstone, thin alternations of very fine sandstone, silt and clay layers showing cyclicity (muddy rhythemites), rocks in the Sandakan Formation are interpreted as mangal estuary and open marine facies. Three facies associations could be deduced from the seven lithofacies: Gradual coarsening upwards shoreface; abrupt change facies and prograding estuary facies association.
Following rapid technological and industrial development, factories have been equipped with a great deal of machines.
The blend of industrial and residential areas in turn resulted in many environmental problems. In particular, machine
operation causes noise pollution that easily causes physiological and psychological discomfort for the human body thus
makes noise abatement a crucial and urgent issue. In this study, vermiculite functional fillers were added to polyurethane
(PU) foam mixtures in order to form sound absorbent PU foams. The correlations between the contents of functional fillers
and the sound absorption of flexible and rigid PU foams were then examined. The optimal PU foams were combined with
PET/carbon fiber matrices in order to yield the electromagnetic shielding effectiveness. The sound absorption, noise
reduction coefficient (NRC), electromagnetic shielding effectiveness and resilience rate of the composite boards were
finally evaluated. The test results indicated that rigid PU foam composites can reach a sound absorption coefficient of
0.8 while the flexible PU foam composites have higher mechanical properties.
Polymeric materials such as polypropylene (PP), polyethylene (PE) and ethylene propylene diene monomer (EPDM) are widely used as insulators for cable applications. We investigated the effect of alumina trihydrate (ATH) loading on the mechanical properties of PP/EPDM blend. Preliminary study showed that PP/EPDM (60:40) was the optimum composition. ATH filled PP/EPDM composites was prepared by using twin screw extruder. In this study, the tensile properties and hardness of the composites were evaluated. The tensile modulus and hardness increased while elongation at break and tensile strength decreased with increasing ATH content. Scanning electron microscope was used to study the morphology of ATH in PP/EPDM blend.