Applied Mechanics and Materials Vol. 575

Abstract: A study was conducted for production of activated carbon (AC) from industrial bamboo waste using carbonization and Microwave-alkali (Mw-A) activation techniques. The aim of the study is to produce activated carbon with higher surface area via Mw-A activation techniques. The study was focused on the effect of activation (KOH soaking and Mw-A) and carbonization temperature (400^oC and 500^oC) on the physical and chemical structure of AC. The analysis was conducted using proximate analysis, BET surface area, FESEM and FTIR analysis. The morphology and characteristic study on activated carbon shown that Mw-A activation techniques gave higher BET surface area and well develop pore structure. The results indicated that Mw-A activation of activated carbon gave BET surface area of 950m²g^-1, whereas by using steam activation only 719 m²g^-1 of BET surface area was recorded. Higher carbonization temperature for Mw-A treated bamboo produced higher surface area of AC. At 500^oC, 1578m²g^-1 BET surface area of AC was achieved. This work highlighted, Mw-A activation can be applied and further enhanced to obtain higher surface area of activated carbon derived from industrial bamboo waste.

Abstract: Microwave processing of metal alloy powders have gained considerable potential in the field of material synthesis. This paper aims to present the effect of powder particle size of Tin Based Alloy sintered using different type of heat source. Tin (Sn) based alloy containing two different sizes, 10 μm and 150 μm of Sn powder were successfully sintered using hybrid microwave and conventional sintering. The overall processing time was reduced by about 93% through microwave sintering. The comparative analysis is based on densification parameter, microhardness, microstructures and XRD detected phases of the specimens. All specimen with 10 μm sintered in microwave exhibited 90% of theoretical density while exhibited 86% lower porosity and possessed 30% higher in microhardness value.

Abstract: Theestablishment of Aquilariaspp in producingagarwoodisgaining more and more attentionlately, especially withgrowinginterest in agarwoodoilextraction. Thus, theoilextractionsomehow produces abundantwaste of processedagarwood.Theintent of thisresearchistoutilizewastefromagarwoodoilextractionprocess,wherethesilicacontentin thiswastewasdetermined.A preliminarystudywasconductedontheeffect of hydrochloricacidtreatments ofagarwoodwasteon FTIR profile. Aftersoakingovernightwithdifferentacidconcentration; 0.3M, 0.5M and 1M, allthesamplesweredried and analyzedbyusingfouriertransform infra red (FTIR). Theresult shows theexistence of silicagroup in thewaste at 1031 cm^-1peak. Thehighestsilicaintensityfoundwas86%,obtainedfromthesample of agarwoodwastetreatedwith 0.3M HCl.However, theintensitydecreasedproportionaltoincreasingacidconcentrationduetothedecrement of thesilicaconcentrationdetectedbytheinstrument.

Abstract: An oxide film was prepared on AZ91D magnesium alloy by anodizing in solution containing sodium metavanadate (NaVO₃). The corrosion resistance of the substrate was investigated at a fixed current density 10 mA/cm² for 5 mins with different concentration of solution in the range of 0 – 1.0 g/l. The surface morphology, phase structure and corrosion resistance of oxide film were studied by optical microscope, scanning electron microscope (SEM) and energy dispersive spectrometry (EDS) and X-ray diffractometer (XRD), potentiodynamic polarization technique and corrosion test.

Abstract: CuO/SnO₂ nanocomposites materials were prepared by solution coprecipitation process using CuO nanowires-rods and SnO₂ nanowires mixture as a starting materials. The mixture materials were put in beaker glass with distilled water and magnetic stering at 90 ^oC for 3 h. The mixture materials were filtered and heated at 980 ^oC for 20 h. The prepared products were investigated by FE scanning electron microscope (FESEM), X-rays photoemission spectroscopy (XPS) and X-ray driffraction technique (XRD). The results showed nanocomposites structures which consisting of CuO and SnO₂ phase.

Abstract: Thetemperature rise during ultrasonic and sonothermal pretreatments had induced the volatilisationof wastewater prior to anaerobic digestion process. In this study,wastewater from palm oil mill which is known as raw palm oil mill effluent (POME) was exposed to ultrasonic irradiation by using an ultrasonic bath at the rate of 37 kHz. Effects ofultrasonic and sonothermaltreatments onphysical properties of raw POME as a result of the volatilisation process were investigated through these analyses: weight reduction, particle sizedistribution and Specific Surface Area (SSA). The weight reduction was observed to be increased by 39.05% after 6 hours ofultrasonic exposure due to volatilisation process in aqueous phase.The combined sonothermal at a temperature of 75^oC resulted in the highest weight reduction, 19%, compared to lower sonothermal temperatures of 45^oC, 55^oC and 65^oC after 1 hour treatment. Looking at particle size distributions after the treatment, the process reduce the Average Particle Size, D[4,3](or de Brouckere mean diameter) while making the SSAincrease, both rather significantly. However, there were slight increase observed in D[4,3] and areduction in SSA after 3 hours of ultrasonic treatment. This is mostly due to thereflocculation process during the ultrasonic treatment. In contrast, an hour ofsonothermaltreatment showed that the D[4,3] of raw POME continuously reduced as the temperature increase from 45^oCto 75^oC.

Abstract: Carbon reinforced aluminium laminate (CARAL) is a fibre metal laminate which consists of layers of carbon fibre and thin layers of aluminium. Buckling strength of CARAL under various support conditions is studied in this paper. Since CARAL is composed of fibre and metal, the pattern of failure of the laminate under compressive loads is truly imperative. The compressive buckling strength depends on geometrical parameters like length and width of the specimen and the sequence in which the layers are stacked. It also depends on the boundary condition. In this study, the critical buckling load is determined by varying the parameters such as aspect ratio (length/width), stacking sequence and boundary condition. Two different boundary conditions are considered, simply supported and fixed support condition. Numerical simulation analysis shows a maximum deviation of 16.72% from experimental results. The different failure modes executed by the laminate under compressive loading are also determined. The critical buckling load of CARAL constrained on all sides is evaluated numerically for different boundary conditions. Buckling load, in this case, takes maximum value when CARAL is clamped on all sides whereas it takes minimum value when the plate is simply supported on three sides keeping the fourth side fixed.

Abstract: In the present study, single-walled nanotubes-poly (vinyl alcohol) (SWNT-PVA) mixed-matrix-membranes (MMMs) are prepared and carefully characterized via various solid-state techniques, including scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). We investigate how the separation performance of SWNT-PVA MMM in an ethanol-water pervaporation system is improved with the loading of SWNTs in the membranes.

Abstract: Study on resistivity changes of local material silicon wafer, doped with Neutron Transmutation Doping (NTD) using Multi Purpose Nuclear Reactor (MPR-30) was carried out. Two kinds of local material of intrinsic silicon wafer were used as samples for this experiment. These local silicon wafers have no shallow doping. The first have resistivity of between (0.7960 – 0.8010) Ω cm (sample 1). The second have resistivity of between (18.6000 – 33.0000) Ω cm (sample 2). The samples were cleaned with distilled water, and acetone. The samples were sprayed with high pure nitrogen gas. The natural oxide layer on the surface of the local silicon wafer was etched with HF for 1 until 3 minutes. The local silicon wafer was inserted into the aluminum tube. The diameter of aluminum tube was 7 inch. High of aluminum tube was 40 cm. The position of the sample 1 was in the aluminum tube 4 cm that was lower than in the sample 2. The local silicon wafers were irradiated with thermal neutron, in Neutron Transmutation Doping (NDT) facility, in research nuclear reactor MPR-30 (Multi Purpose Reactor-30), Indonesia. The power reactor for the experiment was 15 Mega Watt (MW). The thermal neutron flux was 10¹² neutron cm^-2 s^-1. The irradiation time was 264 hours. After irradiated samples, the local silicon wafers were annealed at a temperature of 700 ⁰C, for one hour. The resistivity of local silicon wafers before and after irradiated, measured by four-point probe. The results showed that average resistivity of sample 1 before the irradiated was 0.8120 Ω cm, and after irradiation its resistivity decreased to 0.0673 Ω cm. The average resistivity of sample 2 before the irradiated was 20.4890 Ω cm, and after irradiation its resistivity decreased to 0.9730 Ω cm. The resistivity of sample 1 and sample 2 after irradiation were homogeneous, it means that the doped phosphorus concentrations also homogeneous.

Abstract: We present an automated computation system for large scale design of metamaterials (MTMs). A computer model emulation (CME) technique is used to generate a forward mapping from the MTM particle’s geometric dimension to the corresponding electromagnetic (EM) response. Then the design problem translates to be a reverse engineering process which aims to find optimal values of the geometric dimensions for the MTM particles. The core of the CME process is a statistical functional regression module using a Gaussian Process mixture (GPM) model. The reverse engineering process is implemented with a Bayesian optimization technique. Experimental results demonstrate that the proposed approach can facilitate rapid design of MTMs.