Papers by Keyword: Characterization

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Authors: Jing Ling Li, Xiao Xia Cao, Hua Liang Yu, Yong Jiang Gan
Abstract: Ag-doping TiO2 nanotubes (Ag-TNTs) were synthesized. A double junction is proposed, involving a Schottky junction and p-n junction (denoted as Ag-p-n junction) occurring between the Ag particles and the nanotube surface, as well as forming inside TiO2 nanotubes, respectively. The strongly built-in electric field of the junctions promotes the separation of photo-holes and photoelectrons, enhancing the photocatalytic efficiency. Ag-TNTs were characterized by XRD and TEM. XRD results indicated that a mixture of anatase and rutile phases. The presence of a new peak at 271 cm1 was revealed by Raman spectral analysis of Ag-TNTs.
Authors: Maria Elisa Rodrigues Coimbra, Carlos Nelson Elias, Paulo Guilherme Coelho
Abstract: The objective of this study was to physico/chemically characterize a commercially available and a newly developed Bioglass and also to evaluate their degradation properties. Materials and Method: Two bioresorbable glasses were utilized, a bioglass synthesized at Chemical Engineering College (University of São Paulo, Lorena, São Paulo) (BG1), and the other bioglass utilized was Biogran (BG2) (3i Implant Innovations, Brazil). Particles size distribution histograms were developed for both materials, and then they were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) before and after immersion in simulated body fluid (SBF) for 30, 60, and 90 days. Results: The particle size distribution showed that the mean particle diameters at 10%, 50%, and 90% of the total volume were 17.65, 66.18, and 114.71 µm for BG1, and 354.54, 437.5, 525.00 µm for BG2. SEM images of BG1 showed that the as-received material had a rough surface and as the time of degradation elapsed, this surface became smooth. The images of BG2 showed that the as-received material also had a rough surface, and after immersion in SBF, the material’s crystalline content/morphology could be observed. The X-ray diffraction recorded that BG1 showed a silica peak, not seen at BG2. FTIR revealed that both bioglasses were of similar composition, except for the CO3-carbonate minor peak, present at the BG2 sample. Conclusions: 1. The particle size distribution showed a polydispersed pattern for both materials. 2. The material suffered degradation, and the decomposition increased as a function of immersion in SBF. 3. Both bioglasses had similar composition.
Authors: Helio R. Simoni, Eduardo Saito, Claudinei dos Santos, Felipe Antunes Santos, Alfeu Saraiva Ramos, Olivério Moreira Macedo Silva
Abstract: In this work, the effect of the milling time on the densification of the alumina ceramics with or without 5wt.%Y2O3, is evaluated, using high-energy ball milling. The milling was performed with different times of 0, 2, 5 or 10 hours. All powders, milled at different times, were characterized by X-Ray Diffraction presenting a reduction of the crystalline degree and crystallite size as function of the milling time increasing. The powders were compacted by cold uniaxial pressing and sintered at 1550°C-60min. Green density of the compacts presented an increasing as function of the milling time and sintered samples presented evolution on the densification as function of the reduction of the crystallite size of the milled powders.
Authors: Feng Wang, Mu Sen Li
Abstract: Hydroxyapatite (HA) powders were directly synthesized in simulated body fluid (SBF) at 37°C, without the need for high-temperature calcified. These powders were found to contain trace amount of CO32-, Cl-, Na+ and K+ impurities, originated from the of SBF solutions during their deposition. The characterizations of the synthesized HA powders were performed by X-ray diffraction (XRD), Fourier-transformed infra-red spectroscopy (FTIR) and Transmission electron microscope (TEM). The experimental results showed that the HA synthesized by the SBF route might be more close to that human bone in structure and compositions. Furthermore, the processes flow for HA synthesis was optimized and the synthesized mechanism was also discussed.
Authors: F.K. van Dijen, A. Kerber, Uwe Vogt, W. Pfeifer, M. Schulze
Authors: Januarti Jaya Ekaputri, Muhammad Bahrul Ulum, Triwulan, Ridho Bayuaji, Tri Eddy Susanto, Mohd Mustafa Al Bakri Abdullah
Abstract: This paper presents an observation on fly ash quality in East Jawa, Indonesia. The ash samples were collected from 16 fly ashes produced by some Indonesian power plants. The samples are majority categorized as class F fly ashes with good pozzolanic characteristics according to the standard. The samples were examined for their physical, chemical and mechanical properties with compression test. The test was conducted by making some mortars and paste containing fly ash as cement replacement in accordance with three methods. The compressive strength results were compared with the control specimens made from ordinary Portland cement to obtain a strength activity index (SAI). The results showed that physical properties of fly ash influenced the mechanical properties of mortars more than those showed by chemical characterization.
Authors: A.A.A.P. Silva, A.S. Rodrigues, R.X. Freitas, S.E.N. Cury, I.V.F. Suhett, C. Santos
Abstract: In this work, the effect of pressure and direction of compression in the shrinkage and flatness of ZrO2-(Y2O3) dental ceramics were studied. Samples (40x15x15mm) were uniaxial cold pressed at different pressures ranging from 10MPa to 160MPa, and then pre-sintered for further cutting. For comparison, samples were also isostatically cold pressed at 300MPa. The pre-sintered samples were cut longitudinally and transversely to the direction of compression, with final thickness of 1mm. Then the samples were ground and polished, and measured with a micrometer at different positions of the sample. After the measurements, the samples were sintered at 1530C-120 min, and again measures. The results indicate the effect of pressure decline in considerable amounts, up to pressures of about 80MPa. Above this value the differences in shrinkage and warpage are insignificant when compared to isostatically pressed samples.
Authors: A.I. Fernández-Abia, J. Barreiro, Luis Norberto López de Lacalle, Gorka Urbicain
Abstract: Behavior of austenitic stainless steels is not well known and these materials are still considered as difficult to machining materials. Moreover, the continuous increment of cutting speeds and other cutting parameters derived from last technological advances in tool material makes it more difficult to understand the behavior of these materials in high performance machining. A mechanistic model is presented in this paper for cutting force prediction of austenitic stainless steels turned at very high cutting speeds (up to 750 m/min). The developed model allows the estimation of cutting forces in turning when the cutting action occurs on the side cutting edge and nose radius edge for general turning tools. A tool-part geometrical model is proposed and the cutting force coefficients have been calculated by means of characterization tests.
Authors: De Qin Ran, Lin Guo Lu, Wei Dian Zhao, Yong Shang
Abstract: The membrane bioreactor (MBR) systems have been increasingly used in water treatment in recent years. However, fouling by soluble microbial products (SMP) remains one of the key performance limitations for more widespread applications. A brief review concerning the characterization, production, affecting factors, components of SMP in MBR systems is presented.
Authors: Gang Yu, Yun Yang
Abstract: Due to the inconvenience of characterization of the degradation of power battery based on capacity fading, this paper proposes a new characterization measure for battery degradation based on declining point. After the declining point is defined and calculated, Olivier-Louis mode is used to fit the discrete discharge experimental data from NASA, the linear correlation between the declining point and capacity is confirmed by correlation analysis and regression analysis, therefore the declining point is verified to be an effective characterization measure of battery degradation.
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