Abstract: The novel perovskite oxide series of Sm1-xZrxFe1-yMgyO3 (x,y = 0.5, 0.7, 0.9) were synthesized by solid state reaction method. X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and conductivity analysis were carried out. XRD patterns of sintered materials revealed the shifted Bragg reflection to higher angle for the higher content of Zr and Mg. This is related to the ionic size of the dopant elements. Rietveld refinement showed that all compounds crystallized in cubic space group of Fm-3m. SEM images showed that the grains were well defined with highly dense surfaces makes it potential as an electrolyte material in solid oxide fuel cells (SOFCs) or gases sensors. Impedance spectroscopy at 550-800 °C shows that conductivity is higher at higher temperature. Sm0.5Zr0.5Fe0.5Mg0.5O3 shows the highest conductivity of 5.451 × 10-3 S cm-1 at 800 °C. It was observed that 50% molar ratio of Mg and Zr doping performed highest conductivity.
Abstract: To study the low temperature effects of tensile mechanical properties on Hydroxyl-terminated polybutadiene (HTPB) propellant, a quasi-static mechanical experiment was conducted. The results show that tensile mechanical parameters are closely related to strain rate and low temperature. With the decrease of temperature and increase of strain rate, the modulus and tensile strength of HTPB propellant increase obviously. Based on the time-temperature equivalence principle (TTEP), the master curves of tensile strength and initial modulus for HTPB propellant were obtained, which can facilitate the structural integrity analysis of the propellant. The damage of propellant is matrix tearing and dewetting between the filled particles and matrix.
Abstract: The GnF/SU-8 composites are new polymer matrix composites (PMCs) composed of graphite nanoflakes (GnFs) bound together by SU-8 photoresist. The PMCs therefore have excellent ultraviolet (UV) photopatternability and high electrical properties. In spite of the unique material properties of GnF/SU-8 composites, much still remains uncertain about their controllability in both UV photopatternability and electrical properties. Here, we investigate 7 kinds of GnF/SU-8 composites having different GnF concentrations of 5.0 to 25.0 wt.% to characterize the changes in the UV photopatternability (i.e., polymerized thickness and photopattern quality) and electrical conductivity of GnF/SU-8 composites caused by a variation in GnF concentration. The polymerized thickness of GnF/SU-8 composites is measured to be in the range of 4.06 to 23.99 μm, which is inversely proportional to GnF concentration and also directly proportional to UV dose (i.e., 345 to 3,450 mJ/cm2) because of the screening effect of GnF existed in the composites; the photopattern quality at the edge is in inverse proportion to GnF concentration. An increase in GnF concentration leads to a significant change in the electrical conductivity of GnF/SU-8 composites in a proportional way (up to 25.34 S/m). The GnF/SU-8 composites are expected to be widely used as UV photopatternable and electrically conductive PMCs for diverse engineering applications.
Abstract: The graphite nanoflake (GnF)-reinforced polydimethylsiloxane (PDMS) composites (GnF/PDMS composites) are developed as new polymer matrix composites (PMCs) with controllable mechanoelectrical properties. Here, we investigate the effect of GnF concentration on the mechanoelectrical properties (i.e., elastic modulus, fracture strain, and conductivity) of GnF/PDMS composites; the change in the surface morphology of GnF/PDMS composites caused by a variation in GnF concentration is also explored. The mechanoelectrical properties are measured by performing tensile tests on the GnF/PDMS composite specimens with different GnF concentrations of 5.0, 10.0, 12.5, 15.0, 20.0, and 25.0 wt.%. The surface morphology is analyzed in terms of internal void formation and surface roughness. The elastic modulus is measured to be in the range of 1.62 to 13.8 MPa which is proportional to GnF concentration, while the fracture strain and electrical conductivity are respectively characterized to be in ranges of 0.09 to 2.09 and 0.3 to 221.0 S/m which are in inverse proportion to GnF concentration. An increase in GnF concentration leads to increases in internal voids’ amount and surface roughness. The GnF/PDMS composites can be used as sensing materials for detecting both small and large deformations in a variety of engineering applications.
Abstract: Steelmaking is accompanied with releasing a large quantity of solid particle in the form of dust. Electric arc furnace dust (EAFD) is known to have high pH number and traces of heavy metals. The objective of this work was to find a suitable procedure for converting the dust waste into inert and useful byproducts using thermodynamic calculations and experimental investigation. The physical, chemical and mineralogical characteristics of initial EAFD were analyzed using different techniques, such as: X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), grain size analysis and metallography. The pH measurement procedure was carried out in accordance with the standard test method for pH of soils “ASTM 4972-95a”. The results of XRD, SEM and EDS analysis were consistent and showed that Fe2O3, CaO, Al2O3, SiO2, MgO, ZnO and traces of other oxides are in the main composition of the EAFD batches with different relative amounts. Furthermore, the particle size measurements revealed that the EAFD particles are in the 0.1 to 394 μm size range. The pH number was ranging between 11.15 and 12.21 for all measurements. The experimental results were used as input data for thermodynamic calculations and accordingly SiO2 and Al2O3 were among the candidates for making ceramic materials through forming glass regions that surround and encapsulate the iron oxide particles. SiO2 modified samples exhibited better apparent structural properties than other compositions. Whereas Al2O3-modified samples showed variation in the product color. Thus, it is concluded from this work that a mixture of EAFD can be modified by 5-20 wt.% of SiO2 and then fired at 1100°C to make inert ceramic materials with reasonable mechanical properties.
Abstract: In solar energy industry, large amount of slurry wastes were produced during the wafer dicing process. The slurry waste contains silicon, silicon carbide and cutting oil. In this study, silicon in the slurry waste was treated with sodium hydroxide to produce a liquid mixture of the sodium silicate. The residue of the reaction was silicon carbide. The liquid mixture was separated to be a sodium silicate solution and used as a silica precursor for producing the silica powder and a hydrophobic silica aerogel by using the sol-gel method. The products were characterized by Fourier transformation infrared spectroscopy (FTIR) and powder X-ray diffraction (pXRD). Experimental results show that the characteristics of the products produced from the slurry waste are similar to that obtained by using the pure sodium silicate solution. It indicates that the wafer dicing slurry waste has a high potential to be a resource for other industries.
Abstract: Carbon coils were synthesized using C2H2 as source gas and CS2 as an incorporated additive gas under the thermal chemical vapor deposition system. The flow rate of CS2 varied according to the different reaction processes. Geometries of as-grown carbon nanomaterials were developed from vine-type into coil-type with increasing CS2 flow rate from 5 to 20sccm. Above 20sccm of CS2 flow rate, indeed, most of them were appeared as the tiny-sized wavelike nanocoil type geometries. To develop the double helix-type microcoils, namely the carbon microcoils, the injection of CS2 flow was manipulated as the stepwise type on/off-cycle manner. Under the specific condition of the on/off-cycle number, the density of the carbon microcoils was enhanced. The cause for the enhanced formation density of the carbon microcoils by the stepwise type manipulation of CS2 flow injection was suggested and discussed.
Abstract: The presence of heavy metals such as mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), thallium (T1) and ruthenium (Ru) in wastewater, even in trace quantities, could cause a negative impact on our health. The adsorption method has been proven to be the most effective and low-cost method for removing of heavy metals from wastewater. In this study, biomass waste was used as a low-cost precursor for the production of cost-effective charcoal and activated carbon. Solid waste from a common local bamboo species (Gigantochloa sp.) was used to produce charcoal and activated carbon. The simulated wastewater was made with Ruthenium complex (N3) dye solution as the adsorbate. The bamboo charcoal was prepared by carbonization, and activated carbon was prepared by NaOH activation after carbonization. The morphological characteristics, chemical compositions, and the lattice structures of the prepared adsorbents were analyzed using SEM, EDX, and XRD. The adsorption performance of the prepared adsorbents toward N3 dye was evaluated, and the highest adsorption capacity of 1.50 mg/g was obtained from activated carbon. The results showed that the activated bamboo-based charcoal has a better adsorption efficiency when compared to the bamboo charcoal for the treatment of N3 dye in wastewater.
Abstract: As the fifth largest tobacco market in the world, most of the tobacco raw material in Indonesia is utilized for cigarette production. People still unfamiliar with the notion of utilizing tobacco leaves for another purpose. This paper will try to propose a new way to derive benefit from tobacco leaves into biofuel. The method will be done through literature review. The study was focused on 3 things, mainly the potency of tobacco leaves in Indonesia, obtaining and handling raw material and potential market of biodiesel itself. This research resulted that currently, tobacco need to develop in Indonesia because Indonesia is a potential country in the development of biodiesel, especially biodiesel made from tobacco. We also concluded that biodiesel from tobacco has an advantage in terms of increased productivity of oil and biodiesel from tobacco mixed by ordinary diesel can produce lower combustion emissions and improve the performance of diesel engines. Also the market of biodiesel products is still wide open. This market covers the domestic market and international market. In the end of this paper we recomended, the governementt must increase the socialization of the benefits tobacco oil, more tobacco biodiesel industry investment, the new tax policy on tobacco biodiesel and create research agreement with Pertamina or other petroleum industries to build biodiesel industry of tobacco in national scale or international scale.
Abstract: In this study, we report salt-responsive amphoteric terpolymers prepared by copolymerization of acrylamide (AM), 2-acrylamido-2-methylpropanesulfonate (AMPS) and 3-acrylamidopropyl trimethylammonium chloride (ATC), and their use as rheology and fluid loss modifiers in water-based drilling fluid (WDF). The dependence of viscosity and turbidity on NaCl concentration indicates the salt-responsiveness of terpolymers, which results from salt-induced polymer conformation changes. In the presence of large quantities of NaCl, comparing with BT/polyanioins solution, bentonite (BT)/terpolymer solution has better shear thinning and thixotropic performance as well as lower fluid loss. Morphology shows that BT/terpolymer solution with NaCl creates high-quality filtrate cake which is compact and thin. A salt-resistant WDF prepared with terpolymers is evaluated and compared with polyanioinc WDF and polyanionic sulfonated WDF. The salt-resistant WDF possesses more favorable rheology, lower fluid loss and stronger tolerance for temperature, suggesting the potential use of AM/AMPS/ATC terpolymers as high-performance additives for salt-resistant WDFs.