M. H. Tahmasebi, K. Raeissi, M. A. Golozar, A. Vicenzo, M. Bestetti,
Volume 35, Issue 3 (12-2016)
Abstract
In the present investigation, Mn-Ni binary nano-oxide was deposited by potentiodynamic method on stainless steel at room temperature and the effect of annealing process (at 200 oC for 6 h) on microstructure and electrochemical performance of the synthesized pseudocapacitor was studied. The results showed the significant effect of annealing process on increasing the capacitance and decreasing the charge transfer resistance of the electrode. Field Emission Scanning Electron Miscroscopy (FESEM) images depicted interconnected and random nano-flakes in the oxide film microstructure. Moreover, a partially crystallized structure consisting disorder hexagonal birnessite type phase was formed upon annealing in the deposited oxide film with about 10 %at Ni in composition. Based on the galvanostatic charge-discharge plots, the highest specific capacitance (384 F g-1) and specific energy (53 Wh kg-1) were found at specific current of 0.1 A g-1 for the annealed oxide electrode. Finally, cycle life test results at specific current of 10 A g-1 showed an excellent cyclability and an increase of about 23% in specific capacitance of synthesized pseudocapacitor after 5000 charge-discharge cycles in 1 M Na2SO4.
M. Ghalambaz, M. Shamanian, A. M. Eslami, M. Abdollahi, E. Abdoulvand,
Volume 41, Issue 1 (8-2022)
Abstract
This research investigated the bonding properties of AISI 321 austenitic stainless steel from microstructural, mechanical, and corrosion points of view. To obtain the optimal parameters of pulsed current gas tungsten arc welding (PCGTAW), the Taguchi method was used. A cyclic potentiodynamic polarization test evaluated the corrosion resistance of the welded samples. The optimal conditions were achieved when the background current, the pulse current, the frequency, and the percentage of the pulse on time were 50 amps, 140 amps, 5 Hz, and 50, respectively. On the other hand, the analysis of variance showed that the percentage of pulse on time equal to 36 and the background current equal to 46 amperes were the most influential factors on the surface current density of the austenitic stainless steel 321 connection using the PCGTAW process. The mechanical properties were assessed using punch shear testing. In the optimal condition, the maximum shear force and strength were 3200 N and 612 MPa, respectively. The results showed that the most critical factor affecting the bonding properties of 321 steel was the heat input.
