Showing 6 results for Toroghinejad
M. R. Toroghinejad, M. Sayadi and M. M. Moshksar,
Volume 25, Issue 1 (7-2006)
Abstract
Aluminum matrix composites reinforced with Al2O3 and SiC particles (5 Vol%) were produced using the hot powder extrusion method. Extrusion temperature and extrusion reduction in area were chosen in the range of 500 to 600°C and 90 to 95%, respectively. The physical and mechanical properties of the extruded composites such as density, tensile strength, elongation and microhardness were evaluated and discussed as a function of extrusion parameters. The microstructure and fracture surface of the products were examined using SEM. The results showed that the composites were fully densified and reinforcement particles were distributed uniformly in the matrix. Presence of Al2O3 and SiC particles increased both strength and microhardness, but decreased the ductility of the composites. Experimental results for hot extrusion of the compacted powder billets also showed that the extrusion pressure was dependent on the ram speed or deformation strain rate.
A. Azimi Dastgerdi, F. Ashrafizadeh, M. R. Toroghinejad, F. Shahriari , H. Zahraei,
Volume 30, Issue 2 (Dec 2011)
Abstract
In this paper, bare spot defects in hot-dip galvanized sheets were studied in terms of the microstructure and their influence on the corrosion and mechanical properties. Surface characteristics and microstructural features were examined by scanning electron microscopy equipped with energy dispersive spectroscopy microanalysis system. The results showed that the major cause of the bare spots was the lack of wetability of the sheet surface due to contamination, improper heat treatment or chemical composition. Corrosion resistance was evaluated by standard salt spray test. Mechanical properties were examined by tensile testing. The time to red rust was much shorter on the bare spots as compared to other regions, but it appeared that bare spot defects had no significant effect on the mechanical properties of the galvanized steel sheets.
S.s. Sayyedain, H.r. Salimijazi, M.r. Toroghinejad, F. Karimzadeh.,
Volume 33, Issue 1 (Journal of Advanced Materials- Summer 2014)
Abstract
Due to their superior properties such as high specific strength, high creep resistance and high strength at elevated temperatures, aluminum composites reinforced with alumina nano particles are widely used for advanced purposes such as aerospace and auto industries. Lack of an appropriate welding process limits their applications. Transient liquid phase (TLP) bonding is one of the state-of-the-art joining processes. It is used for welding composites and advanced materials. Microstructure and mechanical properties of TLP bonding depend on the bonding time and temperature. In the current study, the effect of bonding time on the microstructure and bonding strength of the TLP diffusion bonded of Al2O3p/Al nanocomposite was investigated. A thin layer of copper deposited by electroplating was used as an interlayer. The bonding times of 20 and 40 min were not sufficient for completing the isothermal solidification, and the bonding strengths were not satisfactory. By increasing the bonding time to 60 min at constant bonding temperature of 580 ºC, the isothermal solidification was completed and the final joint microstructure consisted of soft α-Al phase with dispersed CuAl2 precipitated particles. Decreasing the amount of brittle eutectic structures in the joint seam by increasing the bonding time was the main reason for improvement of the joint shear strength. The maximum joint shear strength was achieved at 580 ºC for 60 min which was about 85% of the shear strength of the base material.
S. Torkian, A. Shafyei, M.r. Toroghinejad, M. Safari,
Volume 35, Issue 3 (Journal of Advanced Materials-Fall 2016)
Abstract
In this paper the effect of deep cryogenic treatment time on microstructure and tribological behavior of AISI 5120 case hardennig steel is studied. The disk shape samples were carburized at 920 ◦C for 6 hours and air cooled; after austenitizing, the samples were quenched in oil.Then immediately after quenching and sanding, the sample were kept in liquid nitrogen for 1, 24, 30 and 48 h and then tempered at 200 ◦C for 2 hours. The wear test was done by ball on disk method using of WC ball at 80 and 110 N load. For characterization of carbides, the etchant solution of CuCl2 (5 gr)+HCl (100 mL) + ethanol (100 mL) was used. The hardness of samples before and after of tempering was measured by vicers method at 300 N load.. The amount of retained austenite was measured by X Ray Diffraction method. For 1DCT and 24DCT samples it was about 8% and 4%; in the other samples, the retained austenite peal was so decreased that it was not visible. The result showed that the hardness increases by deep cryogenic treatment in all speciments. While wear resistance increases in 1DCT and 24DCT samples, it decreases for 30DCT and 48DCT samples in compare with Conventional heat treatment (CHT) sample in both applied loads, such that , 48DCT sample has the least wear resistance. The cause of increament of hardness is due to reduction in amount of retained austenite as a result of deep cryogenic treatment and decreasing in wear resistance after 24 hour, is due to carbide growth and nonhemogenuse distribution in microstructure and then weakening of matrix. So the 24 hour deep cryogenic treatment was the best optimal for AISI 5120 steel.
N. Safari, M. Toroghinejad, M. Kharaziha, V. Saeedi,
Volume 38, Issue 3 (Journal of Advanced Materials-Fall 2019)
Abstract
The aim of this study was to fabricate the Mg-1Al-Cu alloys with various amounts of Cu content (0, 0.25, 0.5 and 1 wt.%) using spark plasma sintering (SPS) approach and evaluation of their degradation rate and biological properties. The results indicated that Cu incorporation (0.25 wt.%) significantly diminish degradation rate from 0.039 cm/h in pure Mg to 0.00584 cm/h in Mg-1Al-0.25Cu alloy. In addition, Mg-1Al-0.25Cu alloy could noticeably (1.25 times) promote viability of MG63 cells compared to pure Mg, owing to the optimized ion release. Moreover, the antibacterial activity of Mg-1Al-0.25Cu was considerable. In summary, Mg-1Al-0.25Cu alloy with appropriate degradation rate, good biocompatibility and antibacterial properties can be introduced as a biodegradable orthopedic implant.
S. Shahzamani, M. R. Toroghinejad, A. Asharfi,
Volume 40, Issue 2 (Journal of Advanced Materials-Summer 2021)
Abstract
In this study, Al/Al2O3 composite was produced by accumulative roll bonding (ARB) process coupled with the plasma electrolytic oxidation (PEO) process. The alumina was grown on Al sheets by electrolyte technique with three different thicknesses (10, 20, and 40 µm). The results showed that incorporation of alumina up to 3.22 vol.% in aluminum matrix enhanced the yield and tensile strength of the composite, whereas increasing the amount of alumina up to 6.25 vol.% deteriorated the tensile properties. In the last part, a serial sectioning process was employed to develop a three-dimensional (3D) representation of the microstructure of Al2O3 particles reinforced Al composite for visualization and finite-element modeling (FEM).
