Proceedings of the 4th International Conference on
Nanostructures (ICNS4)
12-14 March 2012, Kish Island, I.R. Iran
In this research, the effect of the constrained groove pressing process on aluminium plates was studied. In this method, two dies (one with asymmetrical grooves, and the other, flat) were used for pressing the aluminium samples. With respect to the dies geometry, a shear strain equal to 0.58 is applied to some parts of the sample in each pressing run. By repeating the pressing operation, a large and significant amount of plastic strain is applied throughout the sample. In the present investigation, tensile and micro-hardness tests were employed to determine the effect of this process on the mechanical properties of the samples. The results showed that the hardness and strength of the samples increase; and the elongation ability diminishes by increasing the number of pressing steps. A little decrease in strength was observed in the samples for higher numbers of pressing steps. Keywords: Constrained groove pressing; Ultra-fine-grained structures; Severe plastic deformation; Mechanical properties MEC 007
MEC 009
Mechanical Properties of Plasma Sprayed TiO2- Hydroxyapatite Nanostructure Coating on the Ti-6Al-4V Substrate
E. Hassania*, M. Zakerib, M. Tamizifarc a Biomedical Department, Islamic Azad University(Science and Research Branch), Tehran, Iran b Ceramic Department, Materials and Energy Research Center, Karaj, Iran c Materials Science Department, Science and Technology University of Iran, Tehran, Iran *elmira_hassani@yahoo.com
The Effect of Temperature and Particle Volume Fraction on the Viscosity of Transformer Oil-Based Nanofluid
N. Jamshidi, M. Farhadi*, D. D. Ganji, K. Sedighi, M. Ebrahimi, S. Akbarzade Faculty of Mechanical Engineering, Babol University of Technology, Babol, I. R. of Iran *mfarhadi@nit.ac.ir
TiO2 coatings with Hydroxyapatite (HA) were produced by the plasma spray process. Effects of HA content and powder microstructure were investigated. Adhesion strength and wear resistance were measured. Microstructure and morphology of coating were characterized by Xray diffraction (XRD) and scanning electron microscope (SEM). Results show that the nano-structure coating with 10% HA, have the maximum adhesion strength of 41.96 MPa. The wear resistance decreases with increasing HA for both micro- and nano-structured coatings. The nano-structured coatings had the maximum wear resistance. On the basis of Rietveld refinement method, the mean grain size of primary powders reaches from 211.9 and 66.4 nm to 355.6 and 112.1 nm for micro- and nano-structured coatings, respectively. Keywords: Hydroxyapatite; TiO2; Plasma spray MEC 010
For electrical insulation and heat dissipation, transformer oil is essential for power transformers. The effect of adding SiO2 nanoparticles to the transformer oil on the viscosity was investigated in this study. It was shown that the viscosity of transformer oil enhances by adding nanoparticles. The effect of cooling and heating processes on the viscosity of nanofluid was also discussed. The presented data show that the viscosity of transformer oil and transformer oil-based nanofluid decreases as the temperature increases until at the specific temperature, Nanofluid with different volume fractions have the same viscosity as transformer oil. Finally a new correlation based on experimental data is proposed for estimating nanofluid viscosity. Keywords: Transformer oil; Viscosity; Nanofluid; Heating and cooling cycles MEC 008
Improved Tribocorrosion Behavior of Nanostructured Titanium by Sever Plastic Deformation Process
S. Faghihi a*, D. Li b, J.A. Szpunar c a Tissue Engineering and Biomaterials Division, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran 14965/161, Iran b Department of Engineering Physics, Ecole Polytechnique, Montreal, QC, H3C 3A7, Canada c Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, S7N 5A9, Canada *sfaghihi@nigeb.ac.ir
Microstructure Evolution Characterization of an IF Steel During Warm Torsion Process
A. Kolahi* Materials and Energy Research Center, Meshkin Dasht, Karaj, Iran *arkolahi@merc.ac.ir
A titanium stabilized interstitial free (Ti-IF) steel was deformed using warm torsion at 500C. The maximum equivalent strains for warm torsion was 4.8 and 4. Warm torsion makes the grains elongated in deformation direction and divides them to sub-grains. The grain size refines with increasing the strain gradually and at strains more than 3.2 very fine grains (<1m) can be observed in the structure. Moreover, the misorientation angle between grains increases with increasing strain and at equivalent strain of 4.8 more than 55% of grain boundaries are high angle boundaries (misorientation angle >15). Keywords: Warm torsion; Grain refinement; Ultra fine ferrite; EBSD; IF steel
Aseptic loosening induced by wear particles from artificial bearing materials is one of the main causes of malfunctioning in total hip replacements. With the increase in young and active patients, complications in revision surgeries and immense health care costs, there is considerable interest in wear-resistant materials that can endure longer in the harsh and corrosive body environment. Here, the tribological behaviour of nanostructured titanium substrates processed by high-pressure torsion (HPT) is investigated and compared with the coarse-grained samples. The high resolution transmission electron microscopy reveals that a nanostructured sample has a grain size of 510 nm compared to that of 10 m and 50 m for untreated and annealed substrates, respectively. Dry and wet wear tests were performed using a linear reciprocating ball-on-flat tribometer. Nanostructured samples show the best dry wear resistance and the lowest wear rate in the electrolyte. There was significantly lower plastic deformation and no change in preferred orientation of nanostructured samples attributable to the wear process. Electrochemical impedance spectroscopy (EIS) shows lower corrosion resistance for nanostructured samples. However, under the action of both wear and corrosion the nanostructured samples show superior performance and that makes them an attractive candidate for applications in which wear and corrosion act simultaneously. Keywords: Nanostructured titanium; Sever plastic deformation; Wear; Corrosion Abstract Book |INST| Sharif University of Technology|
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