Corrosion and Surface Treatment of Magnesium Alloys
Notice bibliographique
Résumé
fuel supplies and arising environmental problems associated with fuel emission products.Magnesium alloys are a promising alternative to the aluminium alloys currently dominating the transportation industry.However, the limited use of magnesium in engineering applications results mainly from the shortcomings including high reactivity in the molten state, inferior fatigue and creep properties compared to aluminium, poor corrosion and wear resistance [22].One of the main challenges in the use of magnesium, particularly for outdoor application, is to overcome its poor corrosion resistance.Magnesium and its alloys are extremely susceptible to galvanic corrosion, which can cause severe attack in the metal resulting in decreased mechanical stability and an unattractive appearance.Corrosion can be minimized by the use of high purity alloys in which the heavy metal impurities such as iron, nickel and copper are kept below a threshold value.The elimination of bad design, surface contamination, galvanic couples and inadequate or incorrectly applied surface protection schemes can also significantly decrease the corrosion rate of magnesium alloys in service [3].In this chapter, the corrosion characteristic of Mg and Mg alloys are described.Fundamental aspects of magnesium corrosion such as general corrosion, galvanic corrosion, pitting, stress corrosion and corrosion fatigue are reviewed.The factors that control the corrosion behaviour of Mg and Mg alloys are discussed in some detail.Finally, the more recently developed corrosion science and engineering underpinning various surface treatment methods such as electrochemical plating, conversion coating, anodizing, gas-phase coating, organic coating, electrolytic plasma oxidation for magnesium alloys are described. Corrosion characteristics of pure magnesiumMagnesium, like most metals and alloys, relies on a natural surface film to control its corrosion.However, the nature of this film is not thoroughly understood.Good passive films are those that restrict the outward flow of cations, resist the inward flow of damaging anions or oxidants, and rapidly repair themselves in the event of localized breakdown.The structure and composition of the surface films, which depends strongly on environmental and metallurgical factors, such as electrolyte species and impurities in the metal, determine the protective ability of a passive film. Environmental effectsNo material shows high corrosion resistance in all kinds of environments.The high corrosion resistance of materials always refers to some specific environments.Magnesium has its own preferred service environments.However, there are fewer media that are suitable for the magnesium and magnesium alloys compared with other materials, such as steels and aluminum alloys.For example, magnesium and magnesium alloys are usually stable in basic solutions, but in neutral and acidic media they dissolve at high rates [3].This is quite different from aluminum alloys that are normally stable in neutral media but are unstable in both basic and acidic solutions.Magnesium Alloys -Properties in Solid and Liquid States Pb -Pb +2 -0.126 Sn -Sn +2 -0.136 Ni -Ni +2 -0.250 Co -Co +2 -0.277 Cd -Cd +2 -0.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,003 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».