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CONTENTS
Volume 1, Number 3, September 2012
 

Abstract
In this paper the intrinsic influence of micron-sized nickel particle reinforcements on microstructure, micro-hardness tensile properties and tensile fracture behavior of nano-alumina particle reinforced magnesium alloy AZ31 composite is presented and discussed. The unreinforced magnesium alloy (AZ31) and the reinforced nanocomposite counterpart (AZ31/1.5 vol.% Al2O3/1.5 vol.% Ni] were manufactured by solidification processing followed by hot extrusion. The elastic modulus and yield strength of the nickel particle-reinforced magnesium alloy nano-composite was higher than both the unreinforced magnesium alloy and the unreinforced magnesium alloy nanocomposite (AZ31/1.5 vol.% Al2O3). The ultimate tensile strength of the nickel particle reinforced composite was noticeably lower than both the unreinforced nano-composite and the monolithic alloy (AZ31). The ductility, quantified by elongation-to-failure, of the reinforced nanocomposite was noticeably higher than both the unreinforced nano-composite and the monolithic alloy. Tensile fracture behavior of this novel material was essentially normal to the far-field stress axis and revealed microscopic features reminiscent of the occurrence of locally ductile failure mechanisms at the fine microscopic level.

Key Words
magnesium alloy; reinforcements; aluminum oxide and nickel particles; metal-matrix composite; microstructure; microhardness; tensile properties; tensile fracture; mechanisms

Address
T.S. Srivatsan, K. Manigandan and C. Godbole: Division of Materials Science and Engineering, Department of Mechanical Engineering, The University of Akron, Akron, Ohio 443250-3903, USA; M. Paramsothy and M. Gupta: Department of Mechanical Engineering, National University of Singapore 9, Engineering Drive 1, Singapore 117-576, Singapore

Abstract
Brazing Mo using Ti and Ti-15-3 foils has been investigated in the experiment. For traditional furnace brazing, solidification shrinkage voids cannot be completely removed from the joint even the brazing temperature increased to 2013 K and 160

Key Words
laser brazing; molybdenum; titanium base fillers; microstructure

Address
Chia-Chen Lin: Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan; Chung-Shan Institute of Science and Technology, Materials & Electro-Optics Research Division, Lung-Tan, Tao-Yuan 325, Taiwan; Cheng-Han Lee and Ren-Kae Shiue: Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan; Hsiou-Jeng Shy: Chung-Shan Institute of Science and Technology, Materials & Electro-Optics Research Division, Lung-Tan, Tao-Yuan 325, Taiwan

Abstract
In this paper, we report on the obtention of nanocrystalline SrMoO4 synthesized through modified combustion process. These powders were characterized by X-ray diffraction, Fourier Transform Raman and Infrared Spectroscopy. These studies reveal that the scheelite-type SrMoO4 crystallizes in tetragonal structure with I41/a (N#88) space group. Transmission electron microscopy image shows that the nanocrystalline SrMoO4 powders have average size of 18 nm. The optical band gap determined from the UV-V is absorption spectra for the as prepared sample is 3.7 eV. These powders showed a strong green photoluminescence emission. The samples are sintered at a relatively low temperature of 850oC. The morphology of the sintered pellet is studied with scanning electron microscopy. The dielectric constant and loss factor values obtained at 5 MHz for a well sintered SrMoO4 pellet has been found to be 9.50 and 7.5

Key Words
photoluminescence; combustion synthesis; nanostructures; dielectric; band gap; sintering

Address
S. Vidya, Annamma John, and J.K. Thomas: Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College Thiruvananthapuram - 695 015, Kerala, India; Sam Solomon: Dielectric Materials Research Laboratory, Department of Physics, St. John

Abstract
Co-Re alloy development is prompted by the search for new materials for future gas turbines which can be used at temperatures considerably higher than the present day single crystal Ni-based superalloys. The Co-Re based alloys are designed to have very high melting range. Although Co-alloys are used in gas turbine applications today, the Co-Re system was never exploited for structural applications and basic knowledge on the system is lacking. The alloy development strategy therefore is based on studying alloying additions on simple model alloy compositions of ternary and quaternary base. Various strengthening possibilities have been explored and precipitation hardening through fine dispersion of MC type carbides was found to be a promising route. In the early stages of the development we are mainly dealing with polycrystalline alloys and therefore the grain boundary embrittlement needed to be addressed and boron addition was considered for improving the ductility. In this paper recent results on the effect of boron on the strength and ductility and the stability of the fine structure of the strengthening TaC precipitates are presented. In the beginning the alloy development strategy is briefly discussed.

Key Words
Co-base alloy; rhenium; boron; small-angle X-ray scattering; diffraction

Address
D. Mukherji, J. Rosler and J. Wehrs: TU Braunschweig, Institut fur Werkstoffe, Braunschweig, Germany; H. Eckerlebe: Helmholtz-Zentrum Geesthacht, Geesthacht, Germany; R. Gilles: TU Munchen, Forschungs Neutronenquelle Heinz Maier-Leibnitz (FRM II), Garching, Germany

Abstract
In this study, the physical and mechanical properties of bamboo fiber reinforced epoxy composites were studied. Composites were fabricated using short bamboo fiber at four different fiber loading (0 wt%, 15 wt%, 30 wt% and 45 wt%). It has been observed that few properties increases significantly with respect to fiber loading, however properties like void fraction increases from 1.71% to 5.69% with the increase in fiber loading. Hence, in order to reduce the void fraction, improve hardness and other mechanical properties silicon carbide (SiC) filler is added in bamboo fiber reinforced epoxy composites at four different weight percentages (0 wt%, 5 wt%, 10 wt% and 15 wt%) by keeping fiber loading constant (45 wt%). The significant improvement of hardness (from 46 to 57 Hv) at 15 wt%SiC, tensile strength (from 10.48 to 13.44 MPa) at 10 wt% SiC, flexural strength (from 19.93 to 29.53 MPa) at 5 wt%SiC and reduction of void fraction (from 5.69 to 3.91%) at 5 wt%SiC is observed. The results of this study indicate that using particulate filled bamboo fiber reinforced epoxy composites could successfully develop a composite material in terms of high strength and rigidity for light weight applications compared to conventional bamboo composites. Finally, SEM studies were carried out to evaluate fibre/matrix interactions.

Key Words
composites; bamboo fiber; SiC; epoxy; mechanical testing

Address
Sandhyarani Biswas: Department of Mechanical Engineering, N.I.T. Rourkela-769008 (Orissa), India

Abstract
Thermal reactive diffusion coating of vanadium carbide on DIN 2714 steel substrate was performed in a molten borax bath at 950-1050oC. The coating formed on the surface of the substrate had uniform thickness (1-12

Key Words
surface treatments; thermal reactive diffusion coating; corrosion; X-ray analysis; salt bath

Address
M. Aghaie-Khafri and N. Daemi: Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Postal Code 1999143344, Tehran, Iran


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