Effect of Anodizing Voltage on the Growth Kinetics of Porous Anodic Alumina on Al-0.5 wt% Mn Alloys

2013 ◽  
Vol 795 ◽  
pp. 56-59 ◽  
Author(s):  
C.H. Voon ◽  
Mohd Nazree Derman ◽  
U. Hashim ◽  
K.R. Ahmad
Keyword(s):  
Steady State ◽  
Current Efficiency ◽  
Current Density ◽  
Dielectric Breakdown ◽  
Oxide Growth ◽  
Nucleation Process ◽  
Manganese Alloy ◽  
Steady State Current ◽  
Pore Nucleation ◽  
Kinetics Of

In this study, the effect of anodizing voltage on the current density versus time transient, oxide mass and the current efficiency of anodizing of aluminium manganese alloy was reported. It was found that the anodizing voltage facilitated the pore nucleation process and increased the steady state current density. However, when the anodizing voltage is 70V, dielectric breakdown occurred. The current density versus time transient for anodizing conducted at 30 to 60 V were typical while the shape was unusual for anodizing conducted at 70 V. The rate of oxide growth increased as a function of anodizing voltage. The current efficiency of anodizing increased as the anodizing increased from 30V to 70V.

scholarly journals Transient Current Density in a Pair of Long Parallel Conductors

2021 ◽  
Vol 11 (15) ◽  
pp. 6920
Author(s):  
Oldřich Coufal
Keyword(s):  
Steady State ◽  
Cross Section ◽  
Current Density ◽  
Circular Cross Section ◽  
Transient Current ◽  
Constant Current ◽  
Voltage Source ◽  
Sinusoidal Voltage ◽  
Steady State Current ◽  
Maximum Current

Two infinitely long parallel conductors of arbitrary cross section connected to a voltage source form a loop. If the source voltage depends on time, then due to induction there is no constant current density in the loop conductors. It is only recently that a method has been published for accurately calculating current density in a group of long parallel conductors. The method has thus far been applied to the calculation of steady-state current density in a loop connected to a sinusoidal voltage source. In the present article, the method is used for an accurate calculation of transient current using transient current density. The transient current is analysed when connecting and short-circuiting the sources of sinusoidal, constant and sawtooth voltages. For circular cross section conductors, the dependences of maximum current density, maximum current and the time of achieving steady state on the source frequency, the distance of the conductors and their resistivity when connecting the source of sinusoidal voltage are examined.

Substrate interactions in the human type IIa sodium-phosphate cotransporter (NaPi-IIa)

2005 ◽  
Vol 288 (5) ◽  
pp. F969-F981 ◽  
Author(s):  
Leila V. Virkki ◽  
Ian C. Forster ◽  
Jürg Biber ◽  
Heini Murer
Keyword(s):  
Steady State ◽  
Sodium Phosphate ◽  
Complete Removal ◽  
Xenopus Laevis Oocytes ◽  
Charge Movement ◽  
Steady State Current ◽  
Transport Cycle ◽  
Voltage Dependent ◽  
Kinetics Of ◽  
State Charge

We have characterized the kinetics of substrate transport in the renal type IIa human sodium-phosphate cotransporter (NaPi-IIa). The transporter was expressed in Xenopus laevis oocytes, and steady-state and pre-steady-state currents and substrate uptakes were characterized by voltage-clamp and isotope flux. First, by measuring simultaneous uptake of a substrate (32Pi, 22Na) and charge in voltage-clamped oocytes, we established that the human NaPi-IIa isoform operates with a Na:Pi:charge stoichiometry of 3:1:1 and that the preferred transported Pi species is HPO42−. We then probed the complex interrelationship of substrates, pH, and voltage in the NaPi-IIa transport cycle by analyzing both steady-state and pre-steady-state currents. Steady-state current measurements show that the apparent HPO42− affinity is voltage dependent and that this voltage dependency is abrogated by lowering the pH or the Na+ concentration. In contrast, the voltage dependency of the apparent Na+ affinity increased when pH was lowered. Pre-steady-state current analysis shows that Na+ ions bind first and influence the preferred orientation of the transporter in the absence of Pi. Pre-steady-state charge movement was partially suppressed by complete removal of Na+ from the bath, by reducing extracellular pH (both in the presence and absence of Na+), or by adding Pi (in the presence of 100 mM Na). None of these conditions suppressed charge movement completely. The results allowed us to modify previous models for the transport cycle of NaPi-II transporters by including voltage dependency of HPO42− binding and proton modulation of the first Na+ binding step.

Effect of Anodizing Voltage on the Morphology and Growth Kinetics of Porous Anodic Alumina on Al-0.5 wt% Mn Alloys

2013 ◽  
Vol 832 ◽  
pp. 101-106 ◽  
Author(s):  
C.H. Voon ◽  
M.N. Derman ◽  
U. Hashim ◽  
K.L. Foo ◽  
Tijjani Adam
Keyword(s):  
Growth Kinetics ◽  
Pore Diameter ◽  
Dielectric Breakdown ◽  
Anodic Alumina ◽  
Porous Anodic Alumina ◽  
Manganese Alloy ◽  
Interpore Distance ◽  
Dimensional Parameters ◽  
Pore Arrangement ◽  
Kinetics Of

In this study, the effect of anodizing voltage on the morphology of porous anodic alumina and growth kinetics of anodizing of aluminium manganese alloy was reported. It was found that the increasing anodizing voltage affect the morphology and dimensional parameters of porous AAO. Both pore diameter and interpore distance increased as a function of anodizing voltage. The regularity of porous AAO was affected by anodizing voltage. Dielectric breakdown occurred at anodizing voltage of 70 V and led to protrusions and cracks of the porous anodic alumina. Moderate anodizing voltage promoted the formation of well ordered pore arrangement while disordered pore arrangement was observed when the anodizing voltage was too low or too high. The thickness of porous AAO increased as the anodizing voltage increased.

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