Corrosion of Magnesium at High Anodic Potentials

Beck, T. R.; Chan, Sandra G.

doi:10.1149/1.2119940

Cited by 28 publications

(23 citation statements)

References 11 publications

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“…The sign of the difference effect that shows a positive or negative value, according to the relationship among individual corrosion current terms, depends mainly upon the alloy system, corrosive medium, range of applied current, etc [2][3][4][5][6]. For example, in Al and Ti alloy or some other ferrous alloys, it shows a positive difference effect in various corrosion conditions [1,2].…”

Section: Negative Difference Effect In Magnesium Alloysmentioning

confidence: 99%

“…However, in the case of Mg-alloy, it shows a negative difference effect, which can be characterized as one of the typical corrosion behaviors of Mg-alloy. However, the formation of monovalent ion [3,4], chunk breakage of metallic part [2,5], and breakage of surface protective film [6] have been suggested as the main causes of the negative difference effect of Mg-alloy.…”

Section: Negative Difference Effect In Magnesium Alloysmentioning

confidence: 99%

“…The difference in the hydrogen evolution rate with/without application of external potential has been investigated as one of the typical corrosion behaviors of Mg alloy [1][2][3][4][5][6][7][8][9]. The difference effects of Mg-alloy especially reveal a peculiar aspect that has a negative sign, dissimilar to Al and Ti-alloy, which reveal a positive sign under various corrosive environments [1,2].…”

Section: Introductionmentioning

confidence: 99%

“…The difference effects of Mg-alloy especially reveal a peculiar aspect that has a negative sign, dissimilar to Al and Ti-alloy, which reveal a positive sign under various corrosive environments [1,2]. So far, it has been suggested that these phenomena arise from the formation of monovalent ion [3,4], chunk breakage of metallic parts [2,5] and breakdown of surface film [6], which depend on the alloy system and composition, corrosion medium, range of applied potential, etc. [1][2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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Effects of chunk breakage and surface protective film on negative difference effect of magnesium alloys

Lee¹,

Kang

Shin

2001

Met. Mater. Int.

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In the present study, the factors having an affect on the difference effect of Mg-alloy, such as the role of monovalent ion, chunk breakage and surface protective film are discussed in detail. The degree of difference effect of as-cast magnesium alloy increases with Al content and applied external potential. The chunk breakage of precipitate was observed under open circuit potential, as well as applied external potential. Also, the precipitate which is disrupted as chunk type maintained its original morphology as that of as-cast alloy among the corrosion products after a corrosion test. It is thought that chunk breakage is a secondary factor bearing on the difference effect, which varies only the degree of the difference effect, Δ. The main cause for the difference effect of Mg-alloy which reveals a negative sign is due to the corrosion behavior of the surface protective film which is influenced on the Al content of the Mg-rich matrix, e.g., the repassivation tendency.

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Section: Negative Difference Effect In Magnesium Alloysmentioning

confidence: 99%

Section: Negative Difference Effect In Magnesium Alloysmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of chunk breakage and surface protective film on negative difference effect of magnesium alloys

Lee¹,

Kang

Shin

2001

Met. Mater. Int.

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“…As such, automobiles currently possess few magnesium cast parts, averaging only a few pounds per car. Pure magnesium corrodes rapidly in humid atmospheric and/or aqueous environments where anions such as Cl À , Br À , I À , and SO À x promote local and generalized corrosion [2][3][4][5][6][7][8][9][10][11][12]. Compounds like alcohols, ethers, and phenols also attack magnesium [13].…”

mentioning

confidence: 99%

Ionic Liquid Treatments for Enhanced Corrosion Resistance of Magnesium‐Based Substrates

Petro

Schlesinger

Song³

2010

Modern Electroplating

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SONG INTRODUCTIONMagnesium (Mg) is the eighth most abundant element on earth, possessing several advantageous properties including a high strength to weight ratio and one of the lightest metals with a density that is only two-thirds that of aluminum and one-fourth that of iron at 1.74 g cm À3 . Additional properties that contribute to magnesium's versatility in the automotive, electronic, and aerospace industries include a high thermal conductivity, high dimensional stability, good electromagnetic shielding characteristics, high damping characteristics, good machinability, and easy recyclability [1]. These properties make the utilization of magnesium of particular interest to the automotive and aerospace industries where the weight reduction provides a simple means to achieve higher fuel efficiencies without sacrificing structural strength.Despite its many valuable properties, magnesium remains a very reactive element, prone to a number of undesirable properties, including poor corrosion and wear resistance, poor creep resistance, and high chemical reactivity, which have limited its wider industrial use. As such, automobiles currently possess few magnesium cast parts, averaging only a few pounds per car. Pure magnesium corrodes rapidly in humid atmospheric and/or aqueous environments where anions such as Cl À , Br À , I À , and SO À x promote local and generalized corrosion [2][3][4][5][6][7][8][9][10][11][12]. Compounds like alcohols, ethers, and phenols also attack magnesium [13]. Although alloying magnesium with elements such as manganese, aluminum, zinc, zirconium, and rare earths [14,15] can improve its properties, magnesium and its alloys continue to be extremely susceptible to galvanic corrosion, which can cause severe pitting in the metal, resulting in decreased mechanical stability and an unattractive appearance of the surface. Although uniform attack [16][17][18] is generally the most prevalent form of electrochemical corrosion, occurring with equal intensity over the entire surface of the metal, in the case of magnesium, especially pure magnesium, the partially protective surface film makes localized galvanic [19][20][21][22][23][24] and pitting corrosion [25-35] more common and worrisome, largely due to the difficulty in their detection and suppression. Galvanic corrosion occurs when two metals/alloys having differing compositions, and thus standard electrode potentials, are electrically coupled in the presence of an electrolyte. This coupling results in the formation of a galvanic cell, which preferentially corrodes the more reactive, or electronegative, of the two metals. Since magnesium has a highly negative standard electrode potential (E 0 ¼À2.37 V) there are few metal couples with which serious and rapid corrosion does not occur. Pitting corrosion, defined by the formation of small pits on the surface of a metal/alloy, usually stem from galvanic corrosion of a surface defect and progresses similar to crevice corrosion, where stagnant liquid in a crevice begins oxidizing the metal and/or its pass...

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Enhanced corrosion resistance of magnesium and its alloys through the formation of cerium (and aluminium) oxide surface films

Ardelean

Marcus

Fiaud

2001

Materials and Corrosion

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Cerium (and aluminium) oxide layers were formed on magnesium and its alloys (AZ91) by chemical surface treatment with or without subsequent annealing. The corrosion behaviour modifications provided by the formation of these surface films were studied by means of different electrochemical and surface analysis techniques. The electrochemical behaviour, studied in sodium sulphate (Na2SO4) solution, showed (i) a marked shift of the corrosion potential towards more positive values, (ii) a slight inhibition of the cathodic reaction and (iii) a significant decrease of the anodic dissolution current. X‐ray photoelectron spectroscopy (XPS) was used for the characterisation of the composition of the deposited films and of the changes in the film composition during the electrochemical corrosion tests. The components of some oxide films are cerium dioxide (CeO2), aluminium oxide (Al2O3) and aluminium hydroxide (Al(OH)3). Other metallic mixed oxide films were obtained as a function of the solution composition. Very little (or no) change in the oxide film composition during the cathodic and anodic polarization experiments was observed from XPS measurements. Chemical treatment provides thick and moderately adherent protective oxide films. Annealing under oxygen further improves the beneficial effect of the chemical treatment.

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Corrosion of Magnesium at High Anodic Potentials

Cited by 28 publications

References 11 publications

Effects of chunk breakage and surface protective film on negative difference effect of magnesium alloys

Effects of chunk breakage and surface protective film on negative difference effect of magnesium alloys

Ionic Liquid Treatments for Enhanced Corrosion Resistance of Magnesium‐Based Substrates

Enhanced corrosion resistance of magnesium and its alloys through the formation of cerium (and aluminium) oxide surface films

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