Materials Science Forum Vol. 840

Abstract: The purpose of this research is to find the effects of cutting speed on the performance of the ZTA ceramic cutting tool. Three types of ZTA tools used in this study which are ZTA-MgO(micro), ZTA-MgO(nano) and ZTA-MgO-CeO₂. Each of them were fabricated by wet mixing the materials, then dried at 100°C before crushed into powder. The powder was pressed into rhombic shape and sintered at 1600°C at 4 hours soaking time to yield dense body. To study the effect of the cutting speed on fabricated tool, machining was performed on the stainless steel 316L at 1500 to 2000 rpm cutting speed. Surface roughness of workpiece was measured and the tool wears were analysed by using optical microscope and Matlab programming where two types of wear measured i.e. nose wear and crater wear. Result shows that by increasing the cutting speed, the nose wear and crater wear increased due to high abrasion. However, surface roughness decreased due to temperature rise causing easier chip formation leaving a good quality surface although the tool wear is increased.

Abstract: Stainless steel foam has been used for various applications due to their advantages over other materials such as high corrosion resistance, easily availability, and low-cost as well as good mechanical properties. In this work, stainless foam was produced by using foam replication method with different solid loading of SS316L i.e 55 wt%, 60 wt%, 65 wt% and 70 wt% SS316L. The samples were sintered in a vacuum furnace at 1250°C. The sample microstructure was characterized by using scanning electron microscope (SEM) while the elemental component was analyzed by using Energy Dispersive X-ray (EDX). The Archimedes test has been conducted to determine the samples density and porosity. It was found that the best sample is SS316L foam with 65 wt% solid loading with the density and porosity of 1.85 g/cm³ and 76.84% respectively which are similar to the human bone. The sample also has open and interconnected pores.

Abstract: YBa₂Cu₄O₈ has emerged as better choice in superconducting application thank to it strong thermal stability. High pressure techniques had been employed for the preparation of YBa₂Cu₄O₈ but it might costly and/or inconvenient. Several research groups had showed that the YBa₂Cu₄O₈ can also be prepared by conventional solid state method with heating at 1 atm oxygen pressure; however the phase formation processes are yet brief and clear. This work infiltrated the phase formation processes in preparing the YBa₂Cu₄O₈ under solid state method with heating at 1 atm oxygen pressure. The effectiveness of the use of sodium nitrate as an enhancer was brought to light by the experiment results. Significant YBa₂Cu₄O₈ phases were successfully synthesized.

Abstract: Cemented tungsten carbides have been paid much attention due its better mechanical properties with excellent combination of hardness and toughness characteristics. The hard WC particles in the coating provide hardness and wear resistance, while the ductile binder such as Co and Ni contribute to toughness and strength. WC-17wt.% Co and WC-9wt.% Ni powders have been sprayed by the HVOF method to form coatings approximately 300μm and 150μm thick onto AISI 1018 steel substrate. Both coatings have been prepared and supplied by an external vendor. The coatings were examined using optical microscope (OM), scanning electron microscope (SEM), and X-Ray diffraction (XRD). The hardness of both coatings were also measured using Vickers micro-hardness tester. The microstructure of the coatings has been analyzed and found to consist of WC, brittle W₂C phase, metallic W phase, and amorphous binder phase of Co and Ni. It is found that WC-Ni has a higher hardness value compared to WC-Co due to high porosity distribution.

Abstract: Corrosion resistance performance of Sn-3.0Ag-0.5Cu (SAC305) was evaluated in 1 M hydrochloride acid through potentiodynamic polarization. SAC305 shows active-passive corrosion behavior in acidic solution with two dissolution peaks detected in anodic branch. Microstructure analysis revealed that the corrosion product deposited on the surface after polarization was porous and uneven. This limits the protection offered by the passivation film as the porous structure allows further corrosion attack on the underlying solder.

Abstract: The capture of carbon dioxide (CO₂) molecules was achieved by utilizing impregnated long chain fatty amine solid sorbents. The long chain fatty amine impregnated on these solid substrates was octadecylamine (ODA) to improve CO₂ adsorption-desorption capacity. The amine-loaded samples were characterized using nitrogen, N₂ adsorption-desorption isotherm of Brunauer-Emmet-Teller (BET) and thermogravimetry analyzer (TGA). The prepared 25 wt % ODA/SiO₂ exhibit acceptable CO₂ capture capacities of 2.45 wt % CO₂/adsorbent at 25 °C by using CO₂ adsorption-desorption isotherm. TG profile shows that the solid sorbents able to adsorb and desorb CO₂ in equivalent amount.

Abstract: Solid acid (heterogeneous) catalysts have a unique advantage in esterification and transesterification reactions which enhances the use of high acid value oil to be used as feedstock for synthesis of biodiesel. Activated carbon was prepared from walnut shell and activated in two step, first step is (thermal) physical activation calcination at 400 °C. Second step is chemical activation, the Ac were treated phosphoric acid in constant flow of nitrogen. The results obtained that the treated carbon show the amazing physicochemical properties (high surface area, high porosity and high acidity)

Abstract: Developing an environmentally friendly and high-quality of fuel from vegetable oil (triglycerides) have attracted a great attention among the researches. Deoxygenation reaction using Ca-based catalyst is a potentially promising element for removing an oxygen species from organic compounds and converting the molecule to hydrocarbon. Addition of transition metal in the catalysis synthesis studies not only could enhance the properties of the catalyst but also could tune the selectivity toward desired product. Cooperation of mesoporous support such as silica alumina (SA) exhibit unique and excellent properties (high surface area, high porosity) which simultaneously could increase the catalyst activity. In the present studies, a set of bifunctional acid-base supported on the highly mesoporous SA doped with Ca and Ni were synthesized. The Ca (NO)₃ and Ni (NO)₃ were impregnated on the mesoporous SA support and were calcined at 500 °C for 2 h in order to activate the synthesized catalyst. The physicochemical properties of the catalyst were characterized by X-Ray fluorescence spectroscopy (XRF), X-Ray diffraction spectroscopy (XRD), temperature programme desorption carbon dioxide (TPD-CO₂) and temperature programme desorption ammonia (TPD-NH₃) and scanning electron microscopy (SEM).

Abstract: The paper describes some work done on the SEM and XRD characteristic studies of aluminium hydroxide and alumina synthesized by the solvothermal and hydrothermal methods. Hydrothermal process produced boehmite phase aluminium hydroxide while the solvothermal process produced gibbsite phase aluminium hydroxide. Transition reaction study by in-situ XRD shows that the gibbsite is transformed into boehmite before it is converted into alumina. This transformation stage involves a dissolution-recrystallization process. The SEM results show the changes in morphology of the crystals as a result of both these processes.

Abstract: Ore samples, believed to be low grade manganese ore were characterized using XRD, XRF and SEM, before being ground further into very fine particle sizes going through a preliminary leaching process. Sulfuric acid was chosen as the leachant, and leaching was done without any presence of reducing agents.