Papers by Keyword: Energy Dispersive X-Ray (EDX)

Abstract: In electrical engineering, electrical discharge can occur in gaseous, liquid or solid insulating medium. Localized dielectric breakdown that occur at a small portion of a solid or fluid electrical insulation under high voltage stress is called partial discharge (PD). This phenomenon can cause the material to breakdown if there is no proper action taken. Usually it begins within voids, cracks, or inclusions within a solid dielectric, at conductor-dielectric interfaces within solid and in bubbles within liquid dielectrics. In order to modify electrical properties of the original structure then nanocomposite need to be introduced. Nanocomposite is the original structure that has been inserted by nano component (nanofiller) such as silicone dioxide and titanium dioxide. Nanocomposites are also found in nature, for example in the structure of the abalone shell and bone. By adding nano component inside the original component, it can change the mechanical and electric properties. In this study, PD characteristics of polymer-natural rubber blends nanocomposite have been investigated. The samples of nanocomposites were developed by using extrusion method. The high voltage is applied at the electrode arrangement of the test sample. The signals of partial discharges are detected by CIGRE Method II and RC detector and the signals are transferred to the personal computer using LabViewTM software. The result from the software is analyzed to find out the PD characteristics. The results revealed that the highest PD numbers are compositions with no filler while the lowest PD numbers come from sample that use 4% SiO2 as its nanofiller. The physical morphology observation is also conducted to investigate the degradation of the samples.

Abstract: Vertebral compression fractures were simulated by making a hole into sheep vertebrae and by injecting a stabilizing material. The injectable bio-ceramic Xeraspine™ was evaluated together with a commercially available PMMA (Vertebroplastic™) as the reference material. The Vertebrae were harvested after 7 days and prepared for microscopy. The samples were deposited with gold on the surface and thereafter subjected to SEM and EDX analysis. It was found that the Xeraspine-bone interface was composed of a mixture of elements. The Vertebroplastic implant was embedded in a carbon containing tissue, likely a soft tissue capsule. The Xeraspine sample was subjected to high resolution analysis in the TEM combined with EDX measurements. The TEM sample was prepared with a novel technique for preparation of the tissue-material interface (FIB). In the TEM analysis it was found that the interface region consists of ZrO2 together with a mixture possibly consisting of katoite and apatite formed during setting and/or originating from the boneapatite.

Abstract: The paper’s aim is to present the processing of a new master alloy similar to STROBLOY. This alloy represents a combination of two master alloys, already known in aluminum industry (AlTiB and AlSr). The benefits of this new alloy are the cut of Ti, B and Sr consumption, as well as a grain refining/modification ecological technology for Al-Si and Al-Mg-Si alloys. So, this alloy was obtained from binary AlB8, AlSr10 and AlTi10 master alloys melted in an electric resistance furnace and argon atmosphere. Samples were cast in an iron mould. As STROBLOY, this new quaternary alloy contains fast dissolving SrAl4 particles important in modification stage, and nucleating particles such as TiB2 and (Al, Ti)B2 essential for grain refining of aluminum alloys.

Abstract: Barium titanate nanopowders were prepared from the modified oxalate co-precipitation method. Barium chloride dihydrate and potassium titanyl oxalate dihydrate were used as the starting precursors with the mole ratio of Ba:Ti as 1:1. Barium titanyl oxalate complex powders were obtained after adjusting the final of pH of the solution to 1. The precipitates were filtered, washed and dried at 100 oC for 5h. The precipitate powders were calcined at 400-700 oC for 2h. The phase transition was studied by X-ray diffractometry (XRD). Cubic structure of barium titanate was obtained after calcinations at 700 oC for 2h. The morphology and chemical composition were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). The range of particle size was 50-100 nm with irregular in shape. The elemental composition of barium, titanium and oxygen showed the characteristic X-ray energy values.

Abstract: The intergranular microstructure in a liquid phase sintered silicon nitride based ceramic may be viewed as an oxynitride glass-ceramic. This work is concerned with the incorporation of yttrium B-phase, which is a five-component phase, into the intergranular regions of silicon nitride ceramics. The silicon nitride materials were fabricated with the addition of a powdered B-phase parent glass with composition (e/o) 35Y:45Si:20Al:83O:17N, or the addition of a mixture of Y2O3, SiO2 and Al2O3 with cation composition (e/o) 35Y:45Si:20Al. The starting powder mixtures contained 10 wt% of sintering additives. Sintering for 2 h at 1800°C was followed by a two-step post-densification heat treatment in order to promote nucleation and growth of yttrium B-phase. Detailed imaging and elemental analysis of the intergranular regions was carried out by EDX in a FEGTEM.

Abstract: Five-component B-phase may be readily formed through the nucleation and crystallisation heat treatment of nitrogen-rich parent glasses with composition (e/o) 35R:45Si:20Al:83O:17N. This paper is focussed on the B-phase structure where R stands for ytterbium, erbium or yttrium. Fine probe EDX analysis in the TEM has shown that the lenticular B-phase crystals take up a substantial range of composition and that the element R is always clearly anti-correlated with silicon. A larger R3+ cation radius moves the B-phase composition range to lower R contents, and as a consequence of the anti-correlation with silicon, the silicon solid solution range goes to higher values. The EDX results lend support to a B-phase structure consisting of two-dimensional network of randomly linked (Si,Al)(O,N)4 tetrahedra between layers of R3+ cations. It is suggested that, in addition to the random substitution of silicon by aluminium in the (Si,Al)(O,N)4 tetrahedra, a locally increased density in the bi-dimensional network of randomly oriented tetrahedra is associated with an increased density of vacancies in the R3+ cation lattice.

Abstract: 6061 aluminum alloy composite reinforced with α-alumina and aluminum borate is fabricated by casting method. The above mentioned composite has been compared to a similar composite without aluminum borate reinforcement for their machinability. The aluminum borate filler was controlled up to (2.5, 5.0 and 30vol %) on the surface of α-alumina. The reaction zone between alumina and the matrix in both the systems are analyzed with the help of TEM micrographs as well as X-ray diffraction profiles. At the reaction zone between alumina and the aluminum alloys, some spinel-like compounds (MgAl2O4) are identified. Finally, machinability was analyzed with the single point tool machining.

Abstract: Niobium is a strong carbide forming element which is often used in microalloyed steels to control the grain size during thermomechanical treatments and to provide strengthening through precipitation processes. A detailed microscopic investigation is one of the keys for understanding the first stages of the precipitation sequence, thus Transmission Electron Microscopy (TEM) is required. The main difficulty of TEM studies is due to the nanometre scale dimensions of the particles, which makes their detection, structural and chemical characterization delicate. Model Fe- (Nb0.06%,C0.05%) and Fe-(Nb0.05%,C0.03%,N0.03%) ferritic alloys subjected to isothermal annealing treatments have been investigated. High Resolution TEM (HRTEM) and conventional TEM (CTEM) were used to characterise the morphology, nature and location of precipitates. Volume fraction measurements and a statistical approach to the determination of precipitate size histograms have been investigated using Energy Filtered TEM (EFTEM) and High Angle Annular Dark Field (HAADF) imaging. Chemical compositions were quantified by Electron Energy Loss Spectroscopy (EELS). The evolution of precipitate composition with time and temperature is compared with previous simulations obtained from new thermodynamic models based on equilibrium boundary conditions.

Abstract: The demand from patients for aesthetic in posterior teeth restoration has been increasing in recent years. As an alternative to metal alloy restorations used in posterior tooth, aesthetical materials such as ceramics have been more often utilized. Resin cement, a derivative from dental composite, based on the combination of bis-GMA and inorganic filler is used to fixate these ceramic restorations to posterior teeth. Similar to resin composite, incorporated antibacterial agents to resin cement can be an effective way to increase the aesthetic restoration durability. Resin cements C&B® (Bisco) and Fill Magic Dual Cement® (Vigodent) were used in the present study. For experimental resin cement, Triclosan was incorporated to the base cement paste. Samples were investigated by Scanning Electron Microscopy coupled to EDX microprobe (SEM/EDX) and FTIR spectroscopy. The results have demonstrated that the incorporation of antibacterial agents to resin cement is possible through the developed procedure.