Applied Mechanics and Materials Vols. 754-755

Abstract: The paper presents a study about aluminum alloy, allied with Si, Cu, Mn, Mg. The Al-Si-Cu-Mg alloys for foundry are used for parts strongly required and which work at high temperatures, due to their good wear resistance. The industrial Al-Cu alloys contain 12 % cooper, are hipo-eutectic and may be for foundry or deformable. By alloying with magnesium, the Al-Cu alloys become with remarkable properties of resistance and plastic deformation processing. The improvement of mechanical characteristics for Al-Si alloys is realized with metals which forms the intermediate phases with silicon or aluminum, with variable solubility in solid state and which permits the structural hardening by heat treatments (quenching and ageing). From the analysis of dilatogramms, grouped for each sample, with the specific initial length, subjected to successive heating, from ambiance temperature up to 500°C, it is found that, with the appearance of ageing phenomena, on the samples aren’t significant modifications for elongation (few microns), only different may be the form of elongation-temperature curve. This analysis permits the determination of experimental data, regarding the behavior of Al-Si alloy subjected to heat treatments and repeated warming. Therefore, the Al-Si-Cu-Mg alloys, for foundry, are used for manufacture the parts strong required and which work at high temperatures, like pistons for engines with internal burn, parts for machines and reinforcements construction, due to their high usage resistance.

Abstract: In this work, highly mesoporous Ag/ZnO was rapidly developed from rice husk, a cheap agricultural biomass with urea as the reducing agent at acidic medium. A facile and cheap sol-gel method combined with calcination was employed to produce Ag/ZnO 0-D nanoparticles. TEM investigation revealed the formation of spherical and discreet nanoparticles with an average particle size of 13.55 nm. Ag/ZnO with semi-crystalline nature was confirmed from the high-angle XRD study. A type IV isotherm with high Brunauer–Emmett–Teller surface area of 416.78 m²g^-1 was exhibited by Ag/ZnO nanoparticles.

Abstract: The paper presents the conservation state of a XVIII-th century triptych, evaluated by analyzing the materials and the technologies used to create it. The triptych is part of the Neamt Agapia monastery collection. It is made out of hand carved lime wood, painted in egg tempera, by an unknown author. The theme of the triptych is “Annunciation” and it is painted in a miniaturist style, all the architectural details on the background of the icon being oversized. A variety of materials was used to create this art piece: the lime wood for the support, metal for the hinges and hanger and the fish glue used at binder and various pigments. This triptych is extremely important not only for its cultural value, but also for its historical perspective because inside the triptych there is a memorial of the founders of the cemetery church of Agapia monastery. The wooden support, the metallic elements and the painting layer are affected by a series of deteriorations and degradations, all caused by the storage environment, the ageing of the materials and improper handling. In order to determine the conservation state and to authenticate the triptych MO and SEM-EDX were used. Archeometrical characteristics of pigments and binders were identified. The obtained data will be used to established a restoration protocol for the triptych.

Abstract: Energy sources are the utility main important aspect in our daily basic life. However, their cost of operation, installation or maintenance is continuously growing to be highly expensive and to this, the solution is by encouraging the usages of recently famous renewable energy, Proton Exchange Membrane (PEM) Fuel Cell. However, this PEM Fuel Cell is not widespread and still new in Malaysia as well as the research is still in the initial stage. Therefore, the purpose of this research is to design the Automated Calculation of Thermodynamic Potential Applied for PEM Fuel Cell. In this project, two different steps will take place. First, the implementation of block parameters of PEM Fuel Cell via MATLAB simulink software (*.mdl) has been used to calculate the hydrogen pressure against Thermodynamic Potential (E_nernst) value and temperature against E_nernst. In order to ensure that the calculation is accurate, these two different values will be compared with the theoretical calculations. Next, the development of Graphical User Interface (GUI) by using Microsoft Visual Studio is implemented. This GUI is prepared in order to create the application of Automated Calculation of Thermodynamic Potential Applied for PEM Fuel Cell. As a result, the new developed application system is expected to automatically calculate the nominal efficiency and the thermodynamic potential value of PEM Fuel Cell.

Abstract: In general, the presence of moisture and other impurities inside the insulator or oil can cause the breakdown of the power transformer. Polarization and Depolarization Current (PDC) is one of the technique to assess the condition of insulation oil in power transformer and can be applied in many electrical apparatus such as power cables and on load tap changer as well as to estimate conductive and moisture content of the insulation. Basically, it is a technique that is based on time domain measurement and has been used since 1990. For this research, the PDC data will be analyzed using graphical method and statistical technique to classify the transformer faults into a proper range. Lastly, it will be validated with the results from previous research. The output of the research work revealed that in term of the sequence, the results obtain in both graphical technique and the statistical technique is identical with the results presented in previous research. Hence, the range of the faults started with partial discharge, followed by arcing and lastly is the overheating.

Abstract: The voltage potential corrosion effect of aged 5xxx series 5D86 Al alloy were investigated using Open Circuit Potential (OCP). The 5D86 Al alloy were heat treated to 600 °C and soaked in 4 hours time and immediate quenched into iced cold water. Then the heat treated samples were aged at five different temperatures for 4 hours and quenched into iced cold water. Temperatures used to aged 5D86 Al alloy is 150 °C, 250 °C, 350 °C, 450 °C and 550 °C. The phases of Al_xMg_y were investigated using XRD. The hardness of these materials was investigated and studied using Vickers microhardness. The corrosion behavior of 5D86 Al alloys was investigated using Open Circuit Potential (OCP) testing. Solution used for OCP testing is 3.5% NaCl for 120 min with 10 mm² surface area. The voltage potential of 5D86 Al alloys aged at 250 °C was nearing positive value which means the corrosion rate of aged sample at 250 °C have the higher rate corrosion resistance.

Abstract: Geopolymer is new binder manufactured from an aluminosilicate source materials synthesized of geopolymer by polycondensation reaction of geopolymeric precursor and alkali polysilicate. Material contains mostly Silicon (Si) and Aluminium (Al) in amorphous form is a possible to be geopolymer source material. Several minerals and industrial by-product materials have been investigated geopolymer materials essentially as a replacement for Ordinary Portland Cement (OPC) and for advanced high-tech composites, ceramic applications, and also as an inorganic polymer coating. This paper reports microstructure properties of various geopolymer properties which are kaolin, white clay and silica sand, from Saudi Arabia by conducting several tests. The characterization and particle morphology of the various geopolymer sources materials was determined using scanning electron microscopy (SEM). X-Ray Fluorescence (XRF) is conducted according to perform elemental analysis and chemical analysis while X-ray Diffraction Analysis (XRD) investigates crystalline material structure, including atomic arrangement, crystalline size, and imperfections.

Abstract: In this study the performance of regenerated spent carbon for azo dye removal was evaluated in batch and continuous column. The spent carbon was generated by thermal method through pyrolysis process and chemical method by using NaOH 6.0 M solution. Reactive Red 120 (RR120) was selected as a model of azo dye due to its common application in the industries. The regeneration of spent granular activated carbon (GAC) by pyrolysis could produce adsorbent that has the adsorption capacity closer to new GAC. The result indicated that paralysed GAC could potentially apply to replace new GAC for RR120 adsorption. In addition, the continuous adsorption operation in mini column test confirmed that the order of adsorption capacity of each GAC is as follows: new GAC, pirolysed GAC, chemical treated GAC and spent GAC.

Abstract: Ultrasonic irradiation is considered as one of the methods in advanced oxidation processes for water and wastewater treatment. In general, ultrasonic is a disinfection process that is capable to destruct and disintegrate physical and chemical contaminants, as well as pathogenic microorganisms under sonochemistry method. With sufficient frequency, power, duration of treatment and initial concentration of microbe, ultrasonic application is able to perform and cause the death of microorganisms. In addition, ultrasonic as an advanced technology is sustainable to the public health and environmental quality.

Abstract: Fluid loss can be defined as the lost of mud filtrate into a porous permeable formation due to high hydrostatic pressure compared to the formation pressure. This phenomenon may cause some major problems to the workover operation such as formation damage, stuck pipe, and poor cementing job. Thus, in order to prevent fluid loss into formation, an environmentally safe, non-toxic, high biodegradability and low cost of polymer additive in drilling mud was prepared from corn starch as the fluid loss control agent. The purpose of this study is to investigate the potential of utilizing natural polymer-corn starch acting as fluid loss control agents in water-based drilling mud. The filtration and rheological properties of the water-based mud were analyzed at 170 to 200 °F temperature range with 0 to 10 g of corn starch concentration. Experimental results showed that the higher concentration of corn starch gave better fluid loss control behavior. Therefore, there is high potential of corn starch to be used as fluid loss control agent in drilling mud.