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Schematic Interpretation of Anomalies in the Physical Properties of Eu and Yb Among the Lanthanides
Issue:
Volume 6, Issue 4, July 2017
Pages:
165-170
Received:
24 May 2017
Accepted:
2 June 2017
Published:
19 June 2017
Abstract: Lanthanides are the elements in 6th period and the 3rd group of the periodic table. Eu and Yb exhibit some unusual properties compared with the other lanthanides. The author has proposed a diagram to systematically illustrate the properties of the elements, by plotting the Young’s modulus on the ordinate and thermal conductivity on the abscissa. Eu and Yb have much lower Young’s moduli, and are located far from other lanthanides on the diagram. Most lanthanides have hexagonal structures. Eu, however, has a body-centered cubic structure, because it is located on the extension of the curve of alkali metals. Yb has a face-centered cubic (fcc) structure, because it is located on the curve of fcc metals. The positions of Eu and Yb on the diagram are thought to act as a bridge between the lanthanides and other adjacent element groups. As a result, Eu and Yb work as if they were members in the adjacent element groups, which leads to their large atomic radii and their low melting points, etc.
Abstract: Lanthanides are the elements in 6th period and the 3rd group of the periodic table. Eu and Yb exhibit some unusual properties compared with the other lanthanides. The author has proposed a diagram to systematically illustrate the properties of the elements, by plotting the Young’s modulus on the ordinate and thermal conductivity on the abscissa. Eu...
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Synthesis and Characterization of Bone & Teeth Ash and Analysis of Their Influence on the Properties of Bone China
Mst. Sharmin Mostari,
Tasmia Zaman,
Md. Shamimur Rahman
Issue:
Volume 6, Issue 4, July 2017
Pages:
171-177
Received:
30 April 2017
Accepted:
8 May 2017
Published:
29 June 2017
Abstract: The work was done to understand the effects of naturally occurred bone and teeth ash on the physical as well as mechanical properties of bone china products. Both bone and teeth ash was prepared following conventional thermal decomposition method. Locally found cattle bones and tooth was utilized for this purpose. Three different routes of powder or ash preparation i.e. boiling-wood firing, excavating-calcination and boiling-calcination were followed. The calcination temperature was fixed at 950°C-2 hours. After that, density and phase identification of ash was carried out. Finally, bone china product was manufactured using powder compaction and slip casting route. Firing was done at a constant temperature (1150°C-2 hours). Further characterizations (density, percent firing shrinkage, percent water absorption and modulus of rupture measurement) of the sintered samples were evaluated. Boiling-calcination route was found to be the most superlative route. However, enhanced properties of bone china were obtained by the addition of teeth ash.
Abstract: The work was done to understand the effects of naturally occurred bone and teeth ash on the physical as well as mechanical properties of bone china products. Both bone and teeth ash was prepared following conventional thermal decomposition method. Locally found cattle bones and tooth was utilized for this purpose. Three different routes of powder o...
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Effect of Cold Working on Creep Rupture Strength of Alloy617
Yoshiki Shioda,
Kyohei Nomura,
Keiji Kubushiro,
Yoshinori Murata
Issue:
Volume 6, Issue 4, July 2017
Pages:
178-189
Received:
26 May 2017
Accepted:
8 June 2017
Published:
29 June 2017
Abstract: The effect of cold working on the creep rupture strength of Alloy617 was investigated. The creep rupture tests were conducted at temperatures of 700 to 800°C, under stresses from 100 to 350 MPa. At high stress conditions, the creep rupture time of the non-pre-strained samples are similar to those of the pre-strained samples. On the other hand, at low stress conditions, the creep rupture time of the pre-strained samples are longer than those of the non-pre-strained samples. The amount of precipitates near the grain boundaries in the pre-strained sample is higher than that in the non-pre-strained sample. Weak regions such as PFZ and recrystallization grains in the non-pre-strained sample are formed in the early stage of creep compared to the pre-strained sample. At low stress conditions, the precipitates near the grain boundaries in the pre-strained sample play an effective role to pin the grain boundaries and they delay the formation of the weak regions resulting in extension to the creep rupture time.
Abstract: The effect of cold working on the creep rupture strength of Alloy617 was investigated. The creep rupture tests were conducted at temperatures of 700 to 800°C, under stresses from 100 to 350 MPa. At high stress conditions, the creep rupture time of the non-pre-strained samples are similar to those of the pre-strained samples. On the other hand, at l...
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Scientific Research Through Simulation in Africa: Role of HPC in Computational Material Studies
Elicah Nafula Wabululu,
P. W. O. Nyawere,
Daniel Barasa Bem
Issue:
Volume 6, Issue 4, July 2017
Pages:
190-192
Received:
21 April 2017
Accepted:
17 May 2017
Published:
6 July 2017
Abstract: Africa is not investing much in computational materials research. Poor infrastructure in terms of electricity and internet connectivity has made research difficult for computational researchers. High Performing Computers and especially CHPC of South Africa have proven to be a better way of doing research in Africa. It has attracted many researchers in Physics, Chemistry and Biology just to name a few. In these initial studies, LaF3 has been presented as a case study currently being done in CHPC yet miles away from Kenya. With the actual speed achieved and resources used (e.g. twelve times speed and over 20 CPUs). For the lattice parameter for LaF3, the experimental work has given a value of 7.20 Bohr and 7.36 Bohr respectively while our computational results are 7.24 Bohr and 7.37 Bohr respectively. The deviation between experimental and computational proves to be small hence validating our computational research.
Abstract: Africa is not investing much in computational materials research. Poor infrastructure in terms of electricity and internet connectivity has made research difficult for computational researchers. High Performing Computers and especially CHPC of South Africa have proven to be a better way of doing research in Africa. It has attracted many researchers...
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Effect of the Etching on Chemical Mechanical Planarization of the Selective Layer Surface
Issue:
Volume 6, Issue 4, July 2017
Pages:
193-199
Received:
19 June 2017
Accepted:
28 June 2017
Published:
17 July 2017
Abstract: Among other the planarization technologies, Chemical mechanical planarization (CMP) is the unique global planarization technology, which makes it be continuously investigated. The planarization (polishing) and micromachining are of considerable interest to different engineering fields, such as the friction couples that function with the selective transfer and is used to remove excess of metal, obtained in process of selective transfer and for the understanding of planarization and micromachining. For an effective planarization, it is necessary to minimize the surface defects while attaining a good planarity with optimal material removal rate (MRR). These requirements can be met by controlling the chemical and mechanical interactions during the polishing process, or by engineering the slurry chemistry, particles properties, and stability. Effect of the etching during CMP process of the selective layer surface are presented in this paper. To optimize the process of selective layer CMP a blanket selective layer samples were polished with, colloidal silica-based slurry which contains a citric acid and an oxidizer (H2O2). Surface studies using X-ray photoelectron spectroscopy (XPS) were performed on selective layer samples after chemical etching in order to determine the effect that different polishing parameters (i.e., pH and H2O2 concentration) have on the selective layer surface. Then, the samples were passively soaked in an acidic slurry mixture containing different concentrations of H2O2 to determine how the chemical action alone affects the removal of the selective layer. The etching results revealed that a cuprous oxide (Cu2O) forms on the surface of the etched metallic selective layer while polished samples showed CuO and Cu(OH)2. The effect of these selective layer oxide films on the removal of the selective layer in passive etching and CMP is discussed.
Abstract: Among other the planarization technologies, Chemical mechanical planarization (CMP) is the unique global planarization technology, which makes it be continuously investigated. The planarization (polishing) and micromachining are of considerable interest to different engineering fields, such as the friction couples that function with the selective t...
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Correlation of the Effects of Alloying Elements on the Hardenability of Steels to the Diffusion Coefficients of Elements in Fe
Issue:
Volume 6, Issue 4, July 2017
Pages:
200-206
Received:
21 June 2017
Accepted:
5 July 2017
Published:
17 July 2017
Abstract: The effects of various alloying elements on the hardenability of steels are known experimentally, but the reasons for these effects are not well understood. In this work, the upper critical cooling rate was selected as the index of hardenability. Changes in the upper critical cooling rate of steel caused by the presence of alloying elements and the diffusion coefficients of those elements in the ã-phase of Fe, plotted on thermal conductivity–Young’s modulus diagrams, showed similar patterns. The correlation between these factors was studied. Good correlation was found: the upper critical cooling rate decreased linearly with increasing diffusion coefficient of the alloying element in the ã-phase, i.e., the hardenability increased. It is considered that a large diffusion coefficient of an alloy element in the ã-phase increases its entropy and, on cooling, thermodynamically stabilizes the ã-phase, thereby preventing its transformation to the á-phase and retaining the ã-phase at a lower temperature, which consequently favors martensitic transformation even at low cooling rates.
Abstract: The effects of various alloying elements on the hardenability of steels are known experimentally, but the reasons for these effects are not well understood. In this work, the upper critical cooling rate was selected as the index of hardenability. Changes in the upper critical cooling rate of steel caused by the presence of alloying elements and the...
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Parameter Study on the Elastic Recovery Rate of Polymer Micro-channel by Rolling Embossing Process
Issue:
Volume 6, Issue 4, July 2017
Pages:
207-211
Received:
19 July 2017
Published:
19 July 2017
Abstract: To study the influence of process parameters on the elastic recovery rate of polymer micro-channel in the rolling embossing, the nonlinear finite element simulation software ABAQUS is employed. The simulated results show that the elastic recovery rate of micro-channel cross-section decreases with an increase of temperature and decrease of preloading and rolling speed. Using the orthogonal design method, the optimum temperature, preloading and rolling speed parameters can be obtained, the influence order of each factors is temperature>preloading height>rolling speed.
Abstract: To study the influence of process parameters on the elastic recovery rate of polymer micro-channel in the rolling embossing, the nonlinear finite element simulation software ABAQUS is employed. The simulated results show that the elastic recovery rate of micro-channel cross-section decreases with an increase of temperature and decrease of preloadin...
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Adsorptive Removal of Trace Concentration of Fluoride Using Orange Waste Treated Using Concentrated Sulfuric Acid
Hari Paudyal,
Bimala Pangeni,
Katsutoshi Inoue,
Hiroyuki Harada,
Hidetaka Kawakita,
Keisuke Ohto,
Shafiq Alam
Issue:
Volume 6, Issue 4, July 2017
Pages:
212-222
Received:
7 June 2017
Accepted:
21 June 2017
Published:
24 July 2017
Abstract: Novel adsorption gel was prepared from orange juice residue by using boiling concentrated sulfuric acid to create a condensation cross-linking reaction. It was then loaded with Zr(IV) ion to create adsorption sites for fluoride ions. This prepared gel was characterized by IR, EDX, XRD, SEM and chemical analysis. Fluoride adsorption was strongly pH dependent and maximum adsorption occurred at pH 3-4. The maximum adsorption capacity was drastically improved by loading Zr(IV) from 0.21 mmol/g up to 0.71mmol/g at 303 K. The thermodynamic parameters evaluated from adsorption isotherms at varying temperature suggested that adsorption of fluoride onto the present adsorbent is spontaneous and endothermic in nature. The adsorbed fluoride was successfully desorbed using dilute alkaline solution. Trace concentrations of fluoride contained in the actual waste plating solution was completely removed by adding small amounts of this adsorbent.
Abstract: Novel adsorption gel was prepared from orange juice residue by using boiling concentrated sulfuric acid to create a condensation cross-linking reaction. It was then loaded with Zr(IV) ion to create adsorption sites for fluoride ions. This prepared gel was characterized by IR, EDX, XRD, SEM and chemical analysis. Fluoride adsorption was strongly pH ...
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Optical and Electrical Properties of Copper Doped Cadmium Oxy-Sulphide Quaternary Thin Films by MOCVD Technique
Sabur Abiodun Ayinde,
Adetokunbo T. Famojuro,
Oladepo Fasakin,
Bolutife Olofinjana,
Adetayo Victor Adedeji,
Moses Sesan Eluyemi,
Marcus Adebola Eleruja,
Ezekiel Oladele Bolarinwa Ajayi
Issue:
Volume 6, Issue 4, July 2017
Pages:
223-229
Received:
4 January 2016
Accepted:
28 June 2017
Published:
26 July 2017
Abstract: A prepared single solid source precursor was used for the deposition of copper doped oxy-sulphide thin films on glass substrate by MOCVD technique. This was achieved by the pyrolysis of the prepared precursors at 420°C with a flow rate of 2.5 dm3/min for 2 hours. The deposited films were characterized using Rutherford Backscattering Spectroscopy (RBS), Scanning Electron Microscopy (SEM), UV-visible spectrophotometry and four point probe method. RBS analysis showed that the expected elements are present while the thickness was estimated to be 889 nm. The SEM images of the deposited film showed a fine structure with densely packed grains of uniform grain size of about 80 nm, well distributed throughout the entire substrate which is polycrystalline in nature. The film revealed an average transmittance of 80% in the visible region with a direct bandgap of 2.41 eV. The absorbance of the film was observed to be low in the visible and near-infrared regions, and high in UV region. The values of 1 
and 
were obtained as the sheet resistance and resistivity of the film respectively. The deposited quaternary thin film is found to be a promising candidate as window layer and absorber layer for cost effective photovoltaics.
Abstract: A prepared single solid source precursor was used for the deposition of copper doped oxy-sulphide thin films on glass substrate by MOCVD technique. This was achieved by the pyrolysis of the prepared precursors at 420°C with a flow rate of 2.5 dm3/min for 2 hours. The deposited films were characterized using Rutherford Backscattering Spectroscop...
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