Advanced Materials Research Vol. 686

Abstract: The release of arsenic to aqueous environment imposes threats to human health. Montmorillonite supported zero-valent iron (ZVI-MMT) is a material with capability of immobilizing arsenic from aqueous environment. The arsenic adsorption efficiency of ZVI-MMT was obtained. In addition, adsorption kinetics of arsenic contaminated water on the material was determined. Arsenic and iron content was quantified by an inductively coupled plasma mass spectrometer (ICP-MS), interplanar distance of the adsorbent was measured by x-ray diffractometer (XRD), and the morphology of the adsorbent was obtained from a transmission electron microscope (TEM). Isotherm data were analyzed using the Langmuir and Freundlich isotherms. The data fitted well to Langmuir isotherm with derived adsorption capacity of 20.1 mg/g. Kinetics data were analyzed using intra-particle model, Elovich equation, pseudo first-, and pseudo second-order models. Elovich equation and pseudo second-order equation fitted the experimental data with pseudo second-order rate constant of 61.2 x 10-4 g/mg-min.

Abstract: The fabrication of low cost ceramic membranes for microfiltration were studied by using a natural materials (shirasu balloon) which are produced from glassy volcanic materials. The shirasu powder was formed into cylindrical shaped membranes and sintered at five different temperatures from 600 °C to 800 °C using spark plasma sintering (SPS). The porosity and density of membranes were measured according to Archimedes method. The effect of sintering temperatures on microstructure and phase of the membranes has been investigated using FESEM and XRD. A filtration experiment was carried out to study the membrane performance for waste water filtration. The quality of the filtered water was determined by analyse the pH, turbidity, suspended solid, chemical oxygen demand (COD) and biochemical oxygen demand (BOD5). The porosity reduced from 48.9% to 40.32% while the membrane density increased from 1.15 g/cm3 to 1.33 g/cm3 with increasing sintering temperatures from 600 °C to 800 °C. A little shrinkage occur during spark plasma sintering process. From the FESEM microstrcture, the maximum pore size of the membrane that has been observed at 600 °C is about 4.7 µm. Shirasu membrane are able to produce clean and clear treated water during the microfiltration test with membrane sintered at 800 °C and there is an improvement in quality of water that has been filtered. The ceramic water filter was successfully produced without the involvement of the high-tech, sophisticated machines and methods as well as complex materials

Abstract: High speed steels (HSS) is used in manufacturing of cutting tools and wear components because of its superior mechanical properties and wear resistance. In this study, the optimization manufacturing parameters such as compacting pressure and heat treatment temperatures will be studied. The powder of HSS and iron phosphorous were dryly mixed for 30 minutes. The mixed powders were compacted at the pressure in the range of 300- 632 MPa, sintered in the temperature range of 1100 - 1225 °C, annealed in the temperature range of 1100 - 1175 °C and tempered in the temperature range of 500 - 600 °C. The mechanical properties of the samples are analyzed using Vicker’s microhardness tester, universal tensile machine and the microstructures of the sintered sample were observed using field emission scanning electron microscope. Test results revealed that the optimum manufacturing parameters are as follows; (i) compacting pressure of 632 MPa, (ii) sintering temperature of 1200°C, (iii) annealing temperature of 1175 °C, (iv) tempering temperature of 500 °C.

Abstract: The prediction of welding parameters and weld bead geometry for GMAW process in Overhead T-fillet welding position (4F) is presented in this paper. This welding position is applied in construction of steel structures and ship building. The task to discover the range of welding parameter that can deposit quality fillet weld in overhead position is difficult, and the cost of developing them by trial and error is high. Robotic GMAW welder is employed to weld in 4F position with CO2 shielding. The current, voltage and speed as parameters, wire extension at 13mm constant. Only weld coupons are analyzed by macro-etching and the fillet geometry is plotted graphically to display the correlation with the respective welding parameter, particularly the heat input. Trend-lines with mathematical formulas are selected to develop the fillet geometry predictor. The predicted fillet geometry is validated by comparing with the values from actual welded coupons. The mean absolute deviation (MAD) of the predicting calculator is less than 1.0mm, it is therefore accurate and valid for industrial application.

Abstract: This study analyses residual stress measurement using X-Ray diffraction method on ultrafine-polycrystalline diamonds and polycrystalline diamonds films grown using Hot Filament Chemical Vapour Deposition technique (HFCVD) on silicon nitride(Si3N4) and tungsten carbide (WC) substrates in the same chamber at the same time with varied pretreatments prior to HFCVD diamond deposition. Measurements were taken perpendicular to the surface and the measured residual stress states of the diamond films are in compression. Thus, assuming isotropic properties of the film, the diamond films grown have tension residual stress parallel to the surface of the substrate. Residual stress is estimated to have the lowest stress for substrate that has undergone 5g/liter silicon carbide seeding process. Effects of residual stress to adhesion are discussed for both substrates.

Abstract: Iron has been viewed as a promised biodegradable metal for temporary implants but its slow degradation is considered as the main limitation. Some works have been done to improve its degradation rate including by alloying and by processing through powder metallurgy. This work presents new approach to accelerate the degradation rate of iron by infiltrating biodegradable polymer into the pores of bulk iron foam. Solution of poly(L-lactic-co-glycolic acid) or PLGA was infiltrated into the iron foam by vacuum infiltration method to form PLGA-infiltrated porous iron (PIPI). It was found that the existence of PLGA in the iron foam maintained the mechanical property as that of iron foam. Degradation test has shown that the PLGA lead the degradation in PIPI samples. This preliminary work has shown the potentiality of the incorporation of biodegradable polymers into biodegradable metals for tailoring their degradation rate.

Abstract: Ever since the first report of ordered mesoporous silica by the Mobil group, various preparation techniques for mesoporous were extensively studied. In addition to the desirable large surface area, surface of mesoporous silica could be modified for specific catalytic and sensor applications. In this present study, SBA-15 mesoporous silica was prepared and further surface modification was done using organoalkoxysilane (aminopropyl and ethylendiaminopropyl). The resulting bare mesoporous silica, anime-functionalised and diamine-functionalised mesoporous silica were characterized using FTIR, XRD, SEM and EDS for the analysis of incorporation of amine functional groups, phase analysis, powder morphology and elemental analysis.