Showing 3 results for S. Sharafi
M. Adjabshiri, S. Sharafi,
Volume 4, Issue 1 (winter & spring 2007 2007)
Abstract
Abstract: Strength at elevated temperatures and thermal shock resistance of austempered ductile
irons at high temperatures has been less intentioned, because of instability of ausferrite phase. In
this research the tensile properties of this iron and pearlitic ductile cast iron have been
investigated by short time high temperature tensile tests. Also thermal shock tests were done at
the molten lead bath at 1000 C . In these experiments, at first samples were immersed partially in
the molten lead bath for 25 seconds and then either cooled in air or quenched in water. Results of
short time high temperature tensile and thermal shock tests showed that ADI samples have higher
strength and shock resistance than the pearlitic ductile samples.
M. Kazemi Pour, S. Sharafi,
Volume 5, Issue 1 (winter 2008 2008)
Abstract
Abstract: Hardfacing is one of the most useful and economical ways to increase the service life of
components subjected to abrasive wear. Iron based hardfacing alloys have long been considered
as candidate coatings for wear-resistant applications in industry. In the present work two layer of
Fe-34Cr-4.5C%wt hardfacing alloy was deposited on ASTM A36 carbon steel plates by SMAW
method. The microstructure consists of large primary and eutectic M7C3 carbides, metastable
austenite and small amount of secondary carbides. The microstructure was analyzed by optical
and scanning electron microscopes. In the same condition of size, shape, distribution and volume
fraction of carbides the as-welded matrix changed to martensite, tempered martensite and ferrite
by heat treatment processes. The wear resistance was measured by pin-on-disk method under loads
of 5, 10 and 20N and for sliding distance of 1500m. The results showed that the as-welded sample
with austenitic matrix has the most and the ferritic matrix specimen has the least wear resistance.
The predominate mechanisms for mass losses were determined to be micro-cutting, microploughing.
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.
