Abstract. This work details the characterization of anatase nano-TiO 2 particles synthesized from Malaysian mineral precursors using the XRD and EDXRF. The properties that were analyzed were its crystallite sizes, relative crystallinity, phases, and chemical composition. It was determined that the crystallite size was quite small (15.6 nm), although the crystallinity of the sample is relatively low. The anatase phase seems to be dominant (100%), although in some cases when the processing parameters were changed or heat treatment were conducted, the existence of rutile is detected. The chemical composition showed that TiO 2 is the majority compound in the sample (~96%), although some metallic and non-metallic impurities are present (Zr, Nb, and S). It is concluded that Malaysian mineral precursors are capable of producing relatively high quality nano-TiO 2 .Introduction Titania (TiO 2 ) is a compound that is both familiar and abundant, having seen many applications in diverse areas such as pigmentations, cosmetics, coatings and water purification. This attribute is mainly due to the flexibility of titania as a compound, where it comprise of many unique phases and crystal systems that is responsible for its behavior in certain conditions.Titania comprises of eleven phases (some only exist in high pressure states), and four crystal systems (orthorhombic, monoclinic, tetragonal and cubic). Some common phases of titania are anatase (tetragonal), brookite (orthorhombic) and rutile (tetragonal). These phases occur naturally in minerals and are regularly extracted and separated from its ores. Sources of titania includes, but is not limited to, ilmenite (FeTiO 3 ), leucoxene ores, or rutile beach sand. Titania, as seen in its commercial form, is manufactured or processed from these sources using a myriad of methods, which includes the more common methods such as sol-gel method (widely used commercially), the hydrothermal and solvothermal methods, to the specialized and seldom used electrodeposition and the sonochemical method. The uniqueness of titania's attribute depends partly on its fabrication route, where we can see titania produced in different forms and shapes such as tubes (solvothermal) or rods (hydrothermal), segregated spheres (sol-gel), and smooth coatings (electrodeposition) when different fabrication methods are used.

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Fadzil, Employment of fiber laser technology to weld Austenitic stainless steel 304 L with Aluminum alloy 5083 using pre-placed activating flux, (2015), AbstractThe overlapping welding was carried out in keyhole mode between austenitic stainless steel 304 L and aluminum alloy 5083 using a low power fiber laser in continuous irradiation. The significant content of magnesium as the alloying element with low boiling point and high vapor pressure inside the AA 5083 matrix can induce the spatter formation and depression on surface of the weld beads upon laser beam absorption and temperature growth which can deteriorate the mechanical properties and appearance of the joints. To reduce these defects, a variety of single and multi-components activating fluxes including oxide-based TiO 2 and halide-based CaF 2 flux powders were pre-placed on the surface of welding material prior to laser welding. The EDX and XRD analyses in addition to microhardness and shear tests were carried out to characterize the joints. The obtained results showed that, the oxide and halide activating fluxes can significantly improve the joints' strength up to 1.48 and 1.85 times in average respectively compared with autogenous joint. It was deduced that the simultaneous effect of significant decrease in joints' surface depression leading to welds' geometry improvement in addition to less formation of interfacial Fe-Al intermetallics, were the major causes for considerable strength improvements.

Abstract. The objective of this work is to utilize a low-grade synthetic rutile to produce high-grade titania nanoparticles. Due to the nature of the precursor, the hydrothermal method needs modification in order to accommodate the precursors and chemical reagents. The product will be characterized with the XRD (crystallite size and crystallinity), EDXRF (chemical composition), SEM (Morphology), N 2 adsorption-desorption (Surface Area) and UV-Vis-NIR. Results revealed a crystallite size of less than 20 nm, a surface area of 186.8 m 2 /g, a morphology that is a combination of agglomeration and particles, and an optical band gap of 3.23 eV. It is concluded that synthetic rutile is a viable precursor to produce high quality titania nanoparticles.

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