Electrochemical (Corrosion) Behavior of Amorphous/Microcrystalline Ion Plated Fe-Cr Alloy Films

CORROSION ◽  
1982 ◽  
Vol 38 (6) ◽  
pp. 314-318 ◽  
Author(s):  
Welville B. Nowak ◽  
Boniface A. Okorie
Keyword(s):  
Electrochemical Corrosion ◽  
Passive Layer ◽  
Current Data ◽  
Constant Current ◽  
Potential Range ◽  
Potential Region ◽  
Crystalline Substrate ◽  
Electrochemical Corrosion Behavior ◽  
Transient Data ◽  
Current Relaxation

Abstract Amorphous and microcrystalline thin films of chromium-bearing iron alloys produced by ion plating exhibit high resistance to localized (pitting) corrosion in neutral NaCl aqueous solutions. The films are produced by thermal evaporation of the alloys through an argon glow discharge onto Ebrite (Fe-Cr) substrates maintained at low temperatures. Potentiodynamic tests indicate that the ion plated films exhibit a Tafel-like behavior in the “passive” potential range, whereas Ebrite and melt-spun amorphous alloys of composition similar to the films have a constant current passive region. Transient current data obtained from tests at successively higher potentiostatic voltages (V) show that such currents decrease exponentially with time. The current relaxation time constant (τ) of the films are five to ten times larger than those of Ebrite, and increases rapidly with V up to about 0.3 V, decreasing slowly thereafter. For the Ebrite substrate, τ shows only increasing values, but with a sharp discontinuity in the V versus τ curve at about 0.4 V. Transient data obtained for bulk amorphous Metglas 2826A above 0.5 V shows that the variation of τ with V is similar to that of the ion plated films. The results indicate that it takes longer to complete the passive layer on the ion plated films than on the crystalline substrate; the decrease in τ with increasing V in the middle potential region may be related to the amorphous or amorphous/microcrystalline structure of Metglas 2826A and the ion plated films. The results are consistent with a change in the character of the passive layer at 0.3 to 0.4 V.

An Automatic Polarization Apparatus for Electrochemical Corrosion Studies

CORROSION ◽  
1969 ◽  
Vol 25 (12) ◽  
pp. 515-519 ◽  
Author(s):  
W. D. HENRY ◽  
B. E. WILDE
Keyword(s):  
Cathodic Polarization ◽  
Reference Electrode ◽  
Electrochemical Corrosion ◽  
304 Stainless Steel ◽  
Constant Current ◽  
Voltage Source ◽  
Potential Range ◽  
Alloy Development ◽  
Corrosion Studies ◽  
Potentiodynamic Anodic Polarization

Abstract Statistical alloy development programs in which electrochemical screening techniques are used require facilities to produce precision polarization data. Conventional equipment and techniques presently available for such programs are not entirely satisfactory. Therefore, modifications were made to readily available commercial equipment to significantly improve the attainable sensitivity and reproducibility. This paper describes in detail the procedures necessary to produce an apparatus that automatically measures and records anodic and cathodic polarization curves over an applied potential range of ±2.0 volts. Traverse rates between 2 × 10−3 and 3 × 104 volts per hour are attainable and can be used to polarize electrodes through zero volts (with respect to reference electrode) without the necessity of manual switching. A special mode switch is described in detail with which the basic electronic potentiostat can be used as a constant current or constant voltage source by manual selection. The results obtained from three typical polarization experiments: (1) potentiodynamic anodic polarization, (2) galvanodynamic cathodic polarization, and (3) galvanodynamic linear polarization of AISI Type 304 stainless steel in hydrogen saturated 1N H2SO4 at 25 C (77 F), showed the performance of the apparatus to be equal to or superior to that of conventional manual procedures.

Electrochemical corrosion study of Sn–XAg–0.5Cu alloys in 3.5% NaCl solution

2007 ◽  
Vol 22 (9) ◽  
pp. 2573-2581 ◽  
Author(s):  
Udit Surya Mohanty ◽  
Kwang-Lung Lin
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Passive Layer ◽  
Anode Surface ◽  
Nacl Solution ◽  
Breakdown Potential ◽  
Passive Transition ◽  
Electrochemical Corrosion Behavior ◽  
And Shifts

The electrochemical corrosion behavior of Sn–XAg–0.5Cu alloys in 3.5% NaCl solution was examined using potentiodynamic polarization techniques. The Ag content in the alloy was varied from 1 to 4 wt%. The polarization curves obtained for the alloys show an active–passive transition followed by a transpassive region. Sn–XAg–0.5Cu alloys with higher Ag content (>2 wt%) show a strong tendency toward passivation. The passivation behavior has been ascribed to the presence of both SnO and SnO2on the anode surface. Increase in Ag content from 1 to 4 wt% results in a decrease in the corrosion-current density (Icorr) and linear polarization resistance (LPR) of the alloy. Nevertheless, the corrosion potential (Ecorr) shifts toward negative values, and a decrease in corrosion rate is observed. The presence of Cl−ion initiates pitting and is responsible for the rupture of the passive layer at a certain breakdown potential. The breakdown potential (EBR) decreases and shifts toward more noble values with increase in Ag content in the alloy. Surface analyses by x-ray photoelectron spectroscopy (XPS) and Auger depth profile studies confirmed the formation of both Sn(II) and Sn(IV) oxides in the passive layer.

Corrosion of Ferromagnetic Alloys used for Magnetic Retention of Overdentures

1987 ◽  
Vol 66 (9) ◽  
pp. 1456-1459 ◽  
Author(s):  
M.M.A. Vrijhoef ◽  
P.R. Mezger ◽  
J.M. Van der Zel ◽  
E.H. Greener
Keyword(s):  
Saline Solution ◽  
Artificial Saliva ◽  
Electrochemical Corrosion ◽  
Potential Range ◽  
Good Corrosion Resistance ◽  
Ferromagnetic Alloys ◽  
Casting Alloys ◽  
Oral Environment ◽  
Electrochemical Corrosion Behavior ◽  
Magnetic Retention

Three ferromagnetic casting alloys intendedfor use with magnetically retained overdentures (compositions in wt%: #1, Pd 50, Co 47, Ga 2, Pt 1 ; #2, Pd 60, Co 37, Ga 2, Pt 2; #3, Pd 49, Co 46, Ga 2, Pt 2) were investigated. A 0.9% saline solution and an artificial saliva (Meyer) were used for evaluation of the electrochemical corrosion behavior of these alloys, utilizing standard potentiodynamic techniques. All alloys investigated possessed a good corrosion resistance in the potential range of the oral environment (from - -100 to 300 mV versus SCE). In addition, alloys #1 and 3 appeared to be susceptible to pitting above +300 mV (SCE), while #2 was resistant to pitting and was found to passivate in 0.9% saline solution.

scholarly journals Effects of Yttrium Addition on the Microstructure Evolution and Electrochemical Corrosion of SN-9zn Lead-Free Solders Al-Loy

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2549
Author(s):  
Wenchao Yang ◽  
Jun Mao ◽  
Yueyuan Ma ◽  
Shuyuan Yu ◽  
Hongping He ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Microstructure Evolution ◽  
Electrochemical Corrosion ◽  
Lead Free ◽  
Nacl Solution ◽  
Rich Phase ◽  
Yttrium Addition ◽  
Electrochemical Corrosion Behavior ◽  
Lead Free Solders ◽  
Addition Amount

Electrochemical corrosion behavior of ternary tin-zinc-yttrium (Sn-9Zn-xY) solder alloys were investigated in aerated 3.5 wt.% NaCl solution using potentiodynamic polarization techniques, and the microstructure evolution was obtained by scanning electron microscope (SEM). Eight different compositions of Sn-9Zn-xY (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, and 0.30 wt.%) were compared by melting. The experimental results show that when the content of Y reached 0.06 wt.%, the grain size of Zn-rich phase became the smallest and the effect of grain refinement was the best, but there was no significant effect on the melting point. With the increases of Y content, the spreading ratio first increased and then decreased. When the content of Y was 0.06 wt.%, the Sn-9Zn-0.06Y solder alloy had the best wettability on the Cu substrate, which was increased by approximately 20% compared with Sn-9Zn. Besides, the electrochemical corrosion experimental shows that the Y can improve the corrosion resistance of Sn-9Zn system in 3.5 wt.% NaCl solution, and the corrosion resistance of the alloy is better when the amount of Y added is larger within 0.02–0.30 wt.%. Overall considering all performances, the optimal performance can be obtained when the addition amount of Y is 0.06.

Structure and Resistance to Electrochemical Corrosion of NiTi Alloy

2013 ◽  
Vol 203-204 ◽  
pp. 335-338 ◽  
Author(s):  
Bożena Łosiewicz ◽  
Magdalena Popczyk ◽  
Tomasz Goryczka ◽  
Józef Lelątko ◽  
Agnieszka Smołka ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Niti Alloy ◽  
Electrochemical Corrosion ◽  
High Resolution Electron Microscopy ◽  
Potential Method ◽  
Passive Layer ◽  
Open Circuit ◽  
Experimental Conditions ◽  
Electrochemical Tests ◽  
Reflectivity Method

The NiTi alloy (50.6 at.% Ni) passivated for 30 min at 130°C by autoclaving has been studied towards corrosion resistance in aqueous solutions of 3% NaCl, 0.1 M H2SO4, 1 M H2SO4 and HBSS. Structure and thickness of the passive layer (TiO2, rutile) were examined by X-ray reflectivity method and high resolution electron microscopy. Corrosion behavior of this oxide layer was investigated by open circuit potential method and polarization curves. It was found that the corrosion resistance of the passivated NiTi alloy is strongly dependent on the type of corrosive environment. The higher corrosion resistance of the tested samples was revealed in sulfate solutions as compared to chloride ones. The highest resistance to electrochemical corrosion of the NiTi alloy was observed in 0.1 M H2SO4 solution. Susceptibility to pitting corrosion of the tested samples was observed which increased with the concentration rise of chlorine anions in solution. Electrochemical tests for 316L stainless steel carried out under the same experimental conditions revealed a weaker corrosion resistance in all solutions as compared to the highly corrosion resistant NiTi alloy.

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