AC‐Impedance Measurements on Corroded Porous Aluminum Oxide Films

Hitzig, J.; Jüttner, K.; Lorenz, W.J.; Paatsch, W.

doi:10.1149/1.2108756

“…At the same time, all impedance values are much larger than that of the bare AZ91 magnesium alloy, which is only about several hundreds. Two characteristic capacitive arcs are found in the high and medium frequency domain of the EIS, which provide information of the porous and barrier layers of magnesium alloy's anodic film [19][20][21], respectively, while the inductive component of the low frequency domain should correspond to the porous structure of the PEO film, indicating a cathodic process, such as the reduction of H þ , taking place through the pit channels [22][23][24]. So, the impedance value of the sum of the two capacitive loops strongly corresponds to corrosion resistance.…”

Section: Eis Resultsmentioning

confidence: 99%

Plasma electrolytic oxidation of AZ91D magnesium alloy with different additives and its corrosion behavior

Cao

¹

,

Cao

²

,

Zhang

³

et al. 2007

Materials & Corrosion

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Plasma electrolytic oxidation (PEO) of Mg-based AZ91D alloys was investigated using 50 Hz AC anodizing technique in an alkaline borate solution, which contained a new kind of organic additive and without F, P, and Cr. The anodizing technological parameters have been optimized and a kind of ivory-white smooth anodic film with high corrosion resistance was obtained. It was found that the formation of the anodic films was always coupled with sparking and oxygen evolution, whose intensity changed with the additive and anodizing voltage. All EIS plots have two capacitive loops and one low frequency inductive component. Two capacitive arcs present the barrier and porous layer of the PEO film and the inductive component in the low frequency domain is a complex behavior due to the porous structure connected to the electrolyte.EIS plots and fitting results show that a self-sealing process of the PEO firm with different additives takes place in the beginning of immersion time, then corrosion attack becomes a preponderant process to promote the degradation of the film. Tafel results show that PEO treatment decreases the corrosion current density by four, even five orders of magnitude, while additives content does not affect strongly the electrochemical corrosion behavior. Salt spray test shows that the PEO film formed with NaAlO 2 and Na 2 SiO 3 presents good corrosion resistance, over 600 h without any sealing treatment. The difference of corrosion resistance arose by additives examined by electrochemical techniques and salt spray test does not show strict corresponding relationship.

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“…A bajas frecuencias se observa un proceso inductivo, simulado por el subcircuito CpE 3 -R 3 . En la Tabla III se incluyen los valores de los parámetros utilizados en la simulación: Rs es la resistencia del electrolito; R 1 es la resistencia iónica dentro de las picaduras; CpE 1 se asocia con la interfaseóxido/ electrolito; R 2 se relaciona con la resistencia del proceso de corrosión; CpE 2 está relacionado con la interfase aluminio/ electrolito; R 3 esta relacionado con la resistencia del proceso de adsorción; y CpE 3 esta relacionado con el proceso de adsorción en la interfase aluminio/electrolito (18)(19)(20). Se observa una excelente concordancia entre los datos experimentales y los simulados.…”

Section: Resultados Y Discusiónunclassified

Comportamiento frente a la corrosión del material compuesto 2124/SiC

Baile¹,

Alonso²,

López-Caballero³

et al. 2005

Bol. Soc. Esp. Ceram. Vidr.

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Se realiza un estudio comparativo del comportamiento frente a la corrosión de la aleación de aluminio 2124 reforzada con partículas de carburo de silicio, obtenida por pulvimetalurgia y con tratamientos térmicos T4 y T6. Los resultados experimentales muestran que el tratamiento térmico T6 induce la formación de numerosos intermetálicos que reducen la resistencia a la corrosión. Las partículas de carburo de silicio no tienen un comportamiento catódico con respecto a la matriz de aluminio, sin embargo, disminuyen la resistencia a la corrosión, ya que generan zonas más activas en la interfase matriz/ refuerzo, debido a la acumulación de dislocaciones, tensiones residuales y a la precipitación de intermetálicos. Palabras clave: Corrosión, Materiales Compuestos, Aluminio, Tratamientos Térmicos. Corrosion behaviour of 2124/SiC composite materialA comparative study was performed on the corrosion behaviour of an aluminium matrix composite reinforced with silicon carbide particles, obtained by powder metallurgic. The 2124/SiC material was heat treated using T4 and T6 procedures. The T6 heat treatment induced the formation of several intermetallics and reducing the corrosion resistance. The silicon carbide particles did not have a cathodic behaviour as compared with the aluminium matrix. However, these particles produced a diminution in the corrosion resistance due to the formation of more active zones in the matrix/reinforced interface. These ceramic particles caused intermetallic precipitation and deformation originating in the surrounding zones localized corrosion.

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“…The overall impedance Z (j co) of the inhomogeneous damaged coating can be described by model Bin Fig. 7-11 (Titz etal., 1990;Hitzig et al, 1986;Paatsch etal., 1987;Juttner etal., 1989). It combines the ideal film impedance Z L and the impedance of the corrosion process Z corr , which occurs at the substrate/electrolyte interface at the bottom of the pores.…”

Section: Single Layer Impedance Modelmentioning

confidence: 99%

“…The admittance Z" 1 of the parallel combination of Z L and Z corr is the sum of the admittances of both contributions weighted by the degree of coating coverage 0 z (j coy 1 = 0xz L (j coy 1 + aluminum, which consist of a thin barriertype layer and a thick porous layer. The dimensions and properties of both layers are known to depend on the technical conditions of sulfuric acid anodization and the sealing conditions (Titz et al, 1990;Hitzig et al, 1986;Paatsch et al, 1987;Jiittner et al, 1989). The impedance of this sandwich film can be described sufficiently well by the models given in Fig.…”

Section: Single Layer Impedance Modelmentioning

confidence: 99%

Novel Electrochemical Techniques in Corrosion Research

Grundmeier

¹

,

Jüttner

²

,

Stratmann

³

2013

Materials Science and Technology

Self Cite

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The sections in this article are Introduction Experimental Investigation of Corrosion Reactions by Analysis of the Corrosion Products Experimental Investigation of Corrosion Reactions by Following the Chemical Reaction Rate Experimental Investigation of Corrosion Reactions by Following the Rate of the Electrochemical Corrosion Reaction Electrochemical Impedance Spectroscopy and Noise Analysis Introduction The Principle of Dynamic System Analysis Measurement of the Electrochemical Impedance Presentation of Impedance Data Interpretation of Impedance Data The Polarization Resistance Frequency Dispersion Surface Inhomogeneities Single Layer Impedance Model Sandwich Layer Impedance Model Equivalent Circuit Versus Transfer Function The Transport Impedance Iron Corrosion in Neutral Solution Impedance Model of Passive Films Metal Dissolution and Active‐to‐Passive Transition Electrochemical Noise Noise Sources in Electrochemical Systems Noise Measurement Techniques Data Processing Noise Resistance and Polarization Resistance The Scanning Vibrating Electrode Technique Introduction History of Scanning Reference Electrodes Basic Principles of Localized Potential Mapping Localized Electrochemical Impedance Spectroscopy ( LEIS ) Applications of Modern Scanning Electrode Techniques Local Breakdown of Passivity Galvanic Corrosion Inhibition Microbiologically Influenced Corrosion Protective Polymeric Coatings Concluding Remarks Scanning Kelvinprobe Introduction Theory of the Vibrating Condenser Method The Relation between the Volta Potential Difference and Corrosion‐Relevant Properties Electrolyte Covered Metal Surfaces Metals in Humid Air Polymer‐Coated Metals Calibration of the Kelvinprobe Application of the Kelvinprobe: Atmospheric Corrosion Experimental Results Application of the Kelvinprobe: Corrosion Protection by Organic Coatings Experimental Polymer‐Coated Steel Polymer Coated Galvanized Steel Polymer Coated Aluminum Alloys Industrial Coatings Application of the Kelvinprobe: Corrosion Protection by Modified Metal Surfaces Metal Surfaces Modified by Monolayers of Organic Molecules Metal Surfaces Modified by Ultra‐Thin Plasma Polymers Metal Surfaces Modified by Inorganic and Organic Layers

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AC‐Impedance Measurements on Corroded Porous Aluminum Oxide Films

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Plasma electrolytic oxidation of AZ91D magnesium alloy with different additives and its corrosion behavior

Plasma electrolytic oxidation of AZ91D magnesium alloy with different additives and its corrosion behavior

Comportamiento frente a la corrosión del material compuesto 2124/SiC

Novel Electrochemical Techniques in Corrosion Research

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