Advanced Materials Research Vol. 686

Abstract: Geopolymer is cementitious binders that do not require the presence of ordinary Portland cement (OPC). Fly ash with geopolymer formulations prepared with mixing alumino-silicate with the alkaline activator solution has been applied as protective coating material that suitable for high temperature applications such as fire resistant panel. Geopolymer coating samples were cured at 70 °C for 24 hours before sintered using temperatures range from 600 °C to 1500 °C in order to increase strength and improve thermal properties. Curing conditions also have a significant effect on the development of mechanical strength in most cementitious systems. The chemical compositions, microstructure and FTIR were studied. Geopolymer coating samples cures to a glassy texture and effectively used to create a resistant surface. Fly ash geopolymer coating was improved the compressive strength of the coatings materials as high as 40 MPa. This technology develop a geopolymeric mix design that superior use as cementitious coatings with high thermal application.

Abstract: Research in high pressure CO2 environment is important in oil and gas industry due to potential development of high pressure CO2 gas fields. Current understanding limits the use of carbon steel pipeline material in this high pressure CO2 environment due to excessive corrosion rates predicted by corrosion prediction software. The aim of this work is to elucidate the corrosion behavior of X52 steel in high pressure CO2 environment. Electrochemical methods of linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques were employed to study the CO2 corrosion mechanism at high pressures of 10-60 bar at ambient temperature. Surface morphology and chemical composition of corrosion film was studied by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results obtained showed that the corrosion rates at high pressures were significantly influenced by CO2 pressure. However FeCO3 and F3C were the main component of the corrosion product film.

Abstract: Chromium pre-treatments of metal have been replaced by silane pre-treatments as more environmental friendly option. Nanoparticles can be added in the silane sol-gel network have been reported to improve corrosion resistance. In this work, the electrochemical corrosion resistance of low carbon steel coated with hybrid organic-inorganic sol-gel film filled with nanoparticles was evaluated. The sol-gel films have been synthesized from 3-glycidoxy-propyl-trimethoxy-silane (3-GPTMS) and tetra-ethyl-ortho-silicate (TEOS) precursors. These films have been impregnated with 300 ppm of silica or alumina nanoparticles. The electrochemical behavior of the coated steel was evaluated by means of electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Equivalent circuit modeling, used for quantifying the EIS measurements showed that sol-gel films containing silica nanoparticles improved the barrier properties of the silane coating. The silica nanoparticle-containing films showed highest initial pore resistance over the five days of immersion in 0.05M NaCl.

Abstract: The current need to produce lead-free solders in the electronic industries makes it necessary for the replacing solders to have properties which are comparable if not better than the conventional Sn-Pb solders. Thus this research was conducted to compare the corrosion behaviour of lead-free solders with composition Sn-4.0Ag-0.5Cu (SAC405), and Sn-3.0Ag-0.5Cu (SAC305) with conventional Sn-37Pb solders. Corrosion tests were conducted using salt spray tests with 3.5% sodium chloride (NaCl) solutions. The samples were characterized after corrosion tests by using SEM, EDS and XRD. The results showed that the elements present in the solders contributed to galvanic corrosion mechanism that affected the overall corrosion behaviour of the solders.

Abstract: The corrosion of structures is needed to be identified early to prevent any severe damage of buildings. The conventional technique such as potential mapping for diagnosing of reinforced concrete corrosion has been used widely in the field. However, the method has limitation such as less accuracy, laborious and time-consuming. This study is conducted to develop boundary element method 3 dimensions by considering polarization curves of anode and cathode for corrosion simulation and analyzed the influences of anode profiles for RC corrosion simulation. In this method, the potential in concrete domain was modeled by Laplace’s equation. The anode and cathode areas were represented by each polarization curves. The numerical simulation result shows that the boundary element method 3 dimensions successfully solved the Laplace’s equation in order to simulate corrosion phenomenon of reinforced concrete. The influences of anode profiles for RC corrosion simulation have been analyzed. Further works are needed to reduce the computational effort of corrosion simulation.

Abstract: Particle Swarm Optimization (PSO) has been applied as optimization tool in various engineering problems. Inverse analysis is one of the potential application fields for PSO. In this research, the behavior of PSO, related to its inertia weight, in boundary element inverse analysis for detecting corrosion of rebar in concrete is studied. Boundary element inverse analysis was developed by combining BEM and PSO. The inverse analysis is carried out by means of minimizing a cost function. The cost function is a residual between the calculated and measured potentials on the concrete surface. The calculated potentials are obtained by solving the Laplace’s equation using BEM. PSO is used to minimize the cost function. Thus, the corrosion profile of concrete steel, such as location and size, can be detected. Variation in its inertia weight was applied to analyze the behavior of PSO for inverse analysis. The numerical simulation results show that PSO can be used for the inverse analysis for detecting rebar corrosion by combining with BEM. Also, it shows different behavior in minimizing cost function depending on inertia weight.

Abstract: The optimum powder loading of feedstock based on an alumina–zirconia powder was investigated. The optimum powder loading were important to avoid any problems that may arise during the ceramic injection molding (CIM) process. The optimum powder loading is determined based on the critical powder loading and the characterization of the material rheological properties. The critical powder loading was determined using an oil absorption method, and the rheological studies were conducted using a capillary rheometer machine. The results showed that a 57 vol.% powder loading is the most suitable and optimal for the CIM process.

Abstract: Sayong ball clay membrane can be fabricated without the assistance of high-tech sophisticated machineries and complicated production methods make the filters particularly attractive as a point-of-use treatment. This work was concerned with the study of Sayong ball clay membrane as a water filtration by Gel Cast technique. Gel cast involves mixing process of Sayong ball clay with the solvent, monomer, dispersant, initiator and catalyst in a certain composition Tubular membrane was designed and fabricated by controlling the Gel Cast monomer (5, 10, 15, 20 MAM percentage) at sintering temperature of 1300°C. The physical measurements (shrinkage, apparent porosity, bulk density), microstructure analysis, filtration process (flow rate) and water quality assessments (pH, color, COD, SS) were carried out at different percentage of MAM. The porosity and density of membranes were measured by using Archimedes method. The effect of monomer percentage on microstructure of the membranes has been investigated using FESEM. The experimental results showed that the apparent porosity and bulk density of Sayong Ball Clay Gel Cast with 5% MAM and sintered at temperature of 1300°C for 20 minutes were 15.39% and 1.87 g/cm3, respectively. It gives improvement in water quality with the lowest suspended solid (192 mg/L), lowest COD (4 mg/L) and most colorless (1.1 Gardner units) filtered wastewater as compared to others.

Abstract: Amorphous nanosilica entrapped fluorescence dye intended to be used as tracing agent for imaging of cell or tissue in human cell was prepared using micelle entrapment approach. Micelles were produced by mixing a surfactant in water with additives such as butanol and ammonia in a preheated bioreactor. Then, 1,1%-dioctadecyl-3,3,3%,3% tetramethylindocarbocyanine perchlorate (DiI) dye tracing agent was added into the mixture followed by the addition of silica precursor. The parameters studied including effect of surfactant amount, effect of temperature and amount of Si precursor. Silica encapsulated DiI produced were then characterized using Transmission Electron Microscope (TEM), X-ray diffraction (XRD) and UV-Vis NIR spectrophotometer. Dynamic light scattering (DLS) showed that tunable size of nanoparticles in the range of 30-150 nm can be produced by varying synthesis parameters. The results showed that the silica encapsulated DiI became bigger and uniform in size with the increase of temperature and amount of surfactant. The silica encapsulated with DiI is photostable which the intensity of fluorescence value is 279.12 after 90 minutes exposure to halogen lamp (200W) compared to bare DiI that degraded to 100.61.

Abstract: Hydroxyapatite is a calcium phosphate product that being widely use in medical application due to its excellence biocompatibility. However its application has being limited due to the inferior mechanical properties, many researcher attempted to improve its mechanical properties. HA-ZrO2 composites have great potential because of their advantages from both constituent materials, such as the excellent biocompatibility of HA and the considerable mechanical strength and toughness of ZrO2. The synergy of the two materials provides a new possibility for developing a composite material with better properties than monolithic ZrO2 and HA. In this work, the stages of development, as well as the different sintering and processing methods of HA and ZrO2 such as conventional sintering, solid-state reaction, microwave sintering and hot isostatic pressing were discussed. It can be concluded that hot isostatic pressing processing yield the most satisfying result amount above method, however the use of nano structured material maybe able to provide alternative processing method and yield better result.