Showing 2 results for M. H. Shariat
H. Fattahi, M. H. Shariat,
Volume 5, Issue 1 (winter 2008 2008)
Abstract
Abstract: In chloride salt solutions, titanium alloys exhibit reasonably high pitting potentials as
high as +10 V (vs. Ag/AgCl) at room temperatures. On the other hand, anodic pitting potentials
are significantly lower in bromide solutions. In this study, pitting corrosion of commercially pure
titanium in aqueous NaBr solution of 0.1 M concentration at room temperature was studied and
the effect of an external magnetic field oriented both parallel and perpendicular to electrode
surface was investigated. Cyclic potentiodynamic and potentiostatic polarization tests were
carried out. Anodic breakdown potential of +1.45 V (vs. Ag/AgCl) obtained in the absence of
magnetic field, decreasing to +1.11 V in the presence of a 0.05 T parallel magnetic field. The
perpendicular magnetic field actually did not affect the breakdown potential. Applying of an
external magnetic field, independent of its orientation, shifted the repassivation potential
approximately 150 mV in the positive direction. SEM microscopy observations of sample surfaces
indicated that applying of magnetic field results in some variations in the pit shapes and their
sizes.
R. Taherzadeh Mousavian, S. Sharafi, M. H. Shariat,
Volume 8, Issue 2 (spring 2011 2011)
Abstract
Abstract: Nano-structural synthesized materials can be fabricated utilizing intensive milling after combustion synthesis. The Al2O3-TiB2 ceramic composite has been synthesized by aluminothermic reactions between Al, Ti (TiO2), and B (B2O3 or H3BO3). Boric acid (H3BO3) is less expensive than boron oxide, and after being dehydrated at 200°C, boron oxide will be obtained. In this study, Al, TiO2, and boric acid were used as the starting materials to fabricate an Al2O3-TiB2 ceramic composite. After mechanical activation and thermal explosion processes, intensive milling was performed for 5, 10, and 20h to assess the formation of a nano-structural composite. The X-ray phase analysis of the as-synthesized sample showed that considerable amounts of the remained reactants incorporated with the TiO phase were present in the XRD pattern. The results showed that the average crystallite size for alumina as a matrix were 150, 55 and 33 nm, after 5h, 10h, and 20h of intensive milling, respectively. The SEM microstructure of the as-milled samples indicated that increasing the milling duration after combustion synthesis causes a significant reduction in the particle size of the products, which leads to an increase in the homogeneity of particles size. A significant increase in the microhardness values of the composite powders was revealed after intensive milling process.
