Showing 4 results for Kermanpur
M. Eshraghi Kakhki, A. Kermanpur, M. A. Golozar,
Volume 30, Issue 1 (Jun 2011)
Abstract
In this work, a 3D thermo-microstructural model was developed to simulate the continuous cooling of steel. The model was employed for simulation of cooling process of the gears made from a plain carbon steel (AISI 1045) and a low alloy steel (AISI 4140). Temperature-dependent heat transfer coefficients for two different quenching media were evaluated by experimental and computational methods. The effects of latent heat releases during phase transformations, temperature and phase fractions on the variation of thermo-physical properties were investigated. The present model was validated against cooling curve measurements, metallographic analysis, and hardness tests, and good agreement was found between the experimental and simulation results. This model was used to simulate the continuous cooling process and to predict the final distribution of microstructures and hardness in steel gears.
A. Borouni, A. Kermanpur,
Volume 39, Issue 3 (Journal of Advanced Materials-Fall 2020)
Abstract
In this study, the effect of Ta/W ratio on the microstructure and stress rupture properties of Ni-based single crystal (SX) superalloy PWA1483 was investigated. For this purpose, single crystal (SX) superalloys with different Ta/W ratios (0.75, 1.0, 1.32 and 1.5 in wt.%) were fabricated. The alloys were directionally solidified by Bridgman method under the same solidification condition at withdrawal velocity of 3 mm/min and thermal gradient of about 7 K/mm followed by standard age hardening heat treatment. Microstructural characterization was performed using optical microscopy (OM) and scanning electron microscopy (SEM). The stress rupture properties were investigated at 982 °C and 248 MPa. The results showed that increasing the Ta/W ratio decreases the size and volume fraction of micro-pores together with the size of γ' precipitates. Hence, the stress rupture life increased. The superalloy with Ta/W ratio of 1.5 showed the minimum size of micro-porosity (18.2 μm) and the maximum stress rupture life (~34 h). The superalloy with Ta/W ratio of 1 showed the most uniform microstructure and creep behavior. It seems that the presence of topologically closed packed (TCP) η-phases is the main reason for stress rupture life decrease in SX superalloy as micro-pores initiated from TCP phases or the TCP/matrix interfaces.
R. Bagheri, F. Karimzadeh, A. Kermanpur , M. Kharaziha,
Volume 40, Issue 2 (Journal of Advanced Materials-Summer 2021)
Abstract
A new method has been presented for the synthesis of copper (Cu)/copper oxide (CuO)-nanoparticles (NPs), based on the process of corrosion and oxidation of Cu-NPs on the surface of the gold electrode by nitric acid. Cu-NPs were deposited on the surface using potentiometric method. The high concentration of Cu-NPs was estimated by Differential Pulse Voltammetry (DPV). The process of growth and distribution of CuO-NPs on the surface of Cu-NPs using structural analysis of Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) showed that nitrate was well absorbed and a sharp hydroxyl peak appeared and a phase of CuO NPs formed on the electrode surface. The surface morphology indicated that the average size reduced from about 150 nm to 50 nm in the presence of nitrate. This can be due to the oxidation of Cu nanoparticles on the surface and reduction of particle size compared to the absence of nitric acid. This simple and low-cost method can be used as a surface modification of antibacterial and active catalyst electrodes.
Z. Rezay Marand, A. Kermanpur, F. Karimzadeh,
Volume 40, Issue 3 (Journal of Advanced Materials-Fall 2021)
Abstract
Increased demand for clean energy sources, solar cell technology is expanding rapidly. One of the most critical challenges in constructing perovskite solar cells is the lack of an effective hole transport layer with stability and reasonable price. Inorganic p-type semiconductors such as nickel oxide are very cost-effective compared to organic ones. Features such as wide energy gap, high conductivity, stability and resistance to moisture, and solution-based manufacturing process, make the nanostructured inorganic hole transport layer a viable alternative to organic materials. The purpose of this project was to evaluate the characteristics and mechanism of nickel oxide as a hole transport material and fullerene as an interlayer in the structure of inverted nanostructured perovskite solar cells. These solar cells obtained a fill factor of about 71%, a current density of 21.5 mA/cm2, an open-circuit voltage of 1000 mV, and an efficiency of 15.2%.
