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Formation of Gradient Micro-Porous Titanium-Aluminides Through Elemental Powder Metallurgy
Cynthia Kornegay Waters,
Gerald Ross Vosburg,
Stephen Ajinola
Issue:
Volume 7, Issue 2, March 2018
Pages:
33-38
Received:
31 May 2017
Accepted:
12 June 2017
Published:
18 January 2018
Abstract: The research into alloys, specifically titanium and aluminum alloys (Ti & Al), has rapidly growing technological importance. The combined research into Ti-Al alloys in the field of powder metallurgy has advanced the fabrication of a part with high compressive strength, low relative density and material properties in addition to being a cost-effective process. In this work Ti-Al alloys were created using elemental Ti and Al powders. Elemental powders with a melting point of over 1000°C were sintered via liquid phase sintering (LPS). LPS is a process used for forming high performance, multiple-phase components from powders. It involves sintering at a temperature between the melting points of the two powders. The structural morphology, pore size and location were evaluated using Scanning Electron Microscopy (SEM) and optical microscopy. These methods allowed visible evidence of structural anomalies providing a capillary action which pulled the liquid Al to the surface and resulted into a densification of the part at the surfaces. The dense structure was seen on both the top and bottom of the samples with a layer of predominantly Al. The average on the top surface layer using optical measurements was 0.48mm and the bottom was 0.97mm.
Abstract: The research into alloys, specifically titanium and aluminum alloys (Ti & Al), has rapidly growing technological importance. The combined research into Ti-Al alloys in the field of powder metallurgy has advanced the fabrication of a part with high compressive strength, low relative density and material properties in addition to being a cost-effecti...
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Suitability of Vermiculite and Rice Husk Ash as Raw Materials for Production of Ceramic Tiles
Said Abeid,
Seungyong Eugene Park
Issue:
Volume 7, Issue 2, March 2018
Pages:
39-48
Received:
17 December 2017
Accepted:
9 January 2018
Published:
3 February 2018
Abstract: The challenging issues in ceramic tiles are low mechanical strength, thermal discomfort and high production costs. And in most efforts to improve strength, emphasis has been placed on minimization of quartz content in the ceramic tiles formula. This is due to β-α phase inversion of quartz which occurs at 573°C during cooling resulting to the development of stresses which initiate fracture and affects the strength of the final body. The objective of this work was to evaluate the possibility of using vermiculite and rice husk ash (RHA) in the composition of ceramic tile body. Initially, a typical ceramic body composed of the mixture of vermiculite and RHA batched with clay, feldspar, quartz and kaolin was prepared. Ceramic bodies were then obtained from this ceramic mixture by pressing samples at a forming pressure of 35MPa. These bodies were then fired at 1180°C in a laboratory furnace and finally the changes in the physical and mechanical properties caused by the introduction of vermiculite and RHA were tested and evaluated. The chemical composition of the raw samples was analyzed by X-ray fluorescence (XRF) while the phase composition was investigated using X-ray diffraction (XRD). The morphology of the powdered samples was studied by using Scanning electron microscopy (SEM). The bulk density and open porosity of the sintered ceramic bodies were evaluated using Archimedes ‘principle while the flexural rupture strength was determined by the three point bending test method. The major chemical compounds in vermiculite raw sample were SiO2, Al2O3 and Fe2O3 while RHA sample was found to contain mainly SiO2. From the XRD analysis, vermiculite sample had crystalline vermiculite while RHA sample had amorphous silica at low temperature below 900°C and crystallized (tridymite) above 900°C. The results from physical and mechanical properties tests show that with addition of vermiculite and RHA, the percentage of porosity, water absorption and linear shrinkage were increasing while the bulk density and bending strength of the fired ceramic bodies decreased. Among the studied compositions tile bodies made from a blend containing 20% wt. vermiculite and 5% wt. RHA were found to have the best properties for ceramic tiles applications. For this combination the percentage of porosity, water absorption and linear shrinkage were 12.08%, 7.60% and 3.29% while the bulk density and bending strength were 1.88 g/cm3 and 18.84 MPa respectively. These values were close to the required standards of wall and floor tiles.
Abstract: The challenging issues in ceramic tiles are low mechanical strength, thermal discomfort and high production costs. And in most efforts to improve strength, emphasis has been placed on minimization of quartz content in the ceramic tiles formula. This is due to β-α phase inversion of quartz which occurs at 573°C during cooling resulting to the develo...
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Synthesis and Properties for Benzotriazole Nitrogen Oxides (BTzO) and Tris[1,2,4]triazolo[1,3,5]triazine Derivatives
Yanyang Qu,
Qun Zeng,
Jun Wang,
Guijuan Fan,
Jinglun Huang,
Gaungchen Yang
Issue:
Volume 7, Issue 2, March 2018
Pages:
49-57
Received:
7 October 2017
Accepted:
23 October 2017
Published:
26 March 2018
Abstract: Herein we first report a novel method of synthesis fused ring nitrogen-enriched compounds by intramolecular cyclization reaction. Some of them were characterized by IR, 1H and 13C NMR spectroscopy. Most of them exhibit outstanding positive heat of formation (155-376 kJ/mol). Densities of these compounds fall in the range between 1.7321-1.8847 g.cm-1, which places them in a class of relatively dense energetic materials. Their physical properties were evaluated by Gaussian 09, and EXPLO5 6.02 calculations. Their detonation velocities and pressures were calculated to fall in the range of 6713-8441 m.s-1 and 14.47-30.61 Gpa.
Abstract: Herein we first report a novel method of synthesis fused ring nitrogen-enriched compounds by intramolecular cyclization reaction. Some of them were characterized by IR, 1H and 13C NMR spectroscopy. Most of them exhibit outstanding positive heat of formation (155-376 kJ/mol). Densities of these compounds fall in the range between 1.7321-1.8847 g.cm-...
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Storage and Installation of Granite Plugs at the Intersection of the Corridors of the Cheops Pyramid
Аlexandr Mikhailovich Yaroschuk
Issue:
Volume 7, Issue 2, March 2018
Pages:
58-61
Received:
7 February 2018
Accepted:
5 March 2018
Published:
27 March 2018
Abstract: The article investigates the design of the intersection of the Descending and Ascending Corridors in the pyramid of Cheops. Until now there is no convincing indication of the storage location for the granite plugs, and an explanation of how they were delivered and installed. Also, the question remains, how the builders managed to install them so tightly. Many scientists agree that the granite plugs were stored in the Grand Gallery before being used for jamming the intersection, and then were lowered down the Ascending Corridor to the installation site. The article summarizes the earlier versions of the research. In his version, the author proves that the plugs were never placed in the Grand Gallery. The place of their storage could be the special chamber above the intersection. Only in this case, such a tight blockage of the Ascending Corridor is possible. As a proof of his version, the author provides a diagram of the plug installation and an algorithm for their installation.
Abstract: The article investigates the design of the intersection of the Descending and Ascending Corridors in the pyramid of Cheops. Until now there is no convincing indication of the storage location for the granite plugs, and an explanation of how they were delivered and installed. Also, the question remains, how the builders managed to install them so ti...
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Preparation and Characterization of Porous Scaffold Composite Films by Blending Carboxymethyl Chitosan and Gelatin for Tissue Engineering
Nisat Tamanna Nipu,
Farzana Khan Rony,
Asaduz Zaman
Issue:
Volume 7, Issue 2, March 2018
Pages:
62-68
Received:
23 February 2018
Accepted:
9 March 2018
Published:
2 April 2018
Abstract: In this research work, gelatin-carboxymethylchitosan (CMC) based biodegradable composites films were prepared by solution casting method. Chitosan from waste prawn shell was the basic raw materials of CMC synthesis. Five sets of CMC-gelatin composites (5-25 wt% CMC) along-with pure gelatin were prepared in solution casting method. Incorporation of CMC into gelatin significantly altered some of the properties. The CMC and gelatin-CMC composites formation was confirmed by Fourier Transform Infrared Spectroscopy (FTIR). Surface morphology of the films was investigated by Scanning Electron Microscopy (SEM) and SEM micrograph revealed that composites were porous and CMC was homogenously dispersed into gelatin. The porous surface of the composites is one of the criterions for new cells growth. Thermal stability of composites were investigated by thermogravimetric analysis (TGA) and composites more thermal stable (less weight loss) than pure gelatin. Antimicrobial and cytotoxicity tests found all composites were performed microbial safe and no cytotoxic effect. The physico-chemical analyses and others analyses of scaffolds revealed for their application as a wound dressing material or artificial skin.
Abstract: In this research work, gelatin-carboxymethylchitosan (CMC) based biodegradable composites films were prepared by solution casting method. Chitosan from waste prawn shell was the basic raw materials of CMC synthesis. Five sets of CMC-gelatin composites (5-25 wt% CMC) along-with pure gelatin were prepared in solution casting method. Incorporation of ...
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