| Titre : |
Evaluation of surface activity of hot-dip galvanized steel after alkaline cleaning |
| Type de document : |
texte imprimé |
| Auteurs : |
Ville Saarimaa, Auteur ; Carl Lange, Auteur ; Teemu Paunikallio, Auteur ; Aaretti Kaleva, Auteur ; Juha-Pekka Nikkanen, Auteur ; Erkki Levänen, Auteur ; Pasi Väisänen, Auteur ; Antti Markkula, Auteur |
| Année de publication : |
2020 |
| Article en page(s) : |
p. 285-292 |
| Note générale : |
Bibliogr. |
| Langues : |
Américain (ame) |
| Catégories : |
Acier L'acier est un alliage métallique utilisé dans les domaines de la construction métallique et de la construction mécanique.
L'acier est constitué d'au moins deux éléments, le fer, très majoritaire, et le carbone, dans des proportions comprises entre 0,02 % et 2 % en masse1.
C'est essentiellement la teneur en carbone qui confère à l'alliage les propriétés du métal qu'on appelle "acier". Il existe d’autres métaux à base de fer qui ne sont pas des aciers comme les fontes et les ferronickels par exemple.
Alumine
Bases (chimie)
Caractérisation
Chimie des surfaces
Chrome -- Suppression ou remplacement
Dioxyde de carbone
Fluides supercritiques
Surfaces -- Nettoyage
Zinc
|
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
The surface activity of hot-dip galvanized steel was evaluated after alkaline cleaning by exposing the cleaned specimens in humid supercritical carbon dioxide, followed by extraction and quantification of the formed corrosion products. Different free alkalinities of the cleaning bath were studied to obtain information on the evolution of zinc surface activity at different levels of surface etching. Surface reactivity of uncleaned galvanized steel is restricted and local, with major contributions from grain boundaries and intermetallic particles. Formation of zinc corrosion products took place in uncleaned samples exclusively on and around these sites. Al2O3 removal by alkaline cleaning gradually increased the surface activity. The major increase in surface activity was achieved when increasing the free alkalinity from 0.5 to 4.0 mEq/L, which was shown by formation of zinc corrosion products within zinc grains. The surface activity was confirmed by applying a titanium hexafluoride pretreatment on the cleaned panels and measuring the lateral microscale uniformity of the formed layer. The uniformity increased when larger areas of galvanized steel became activated by alkaline cleaning. Reactivity of zinc is rather difficult to quantify when setting up an industrial cleaning sequence for galvanized steel. Controlled exposure of cleaned samples in humid supercritical carbon dioxide, followed by quantification of oxidized zinc, provides a straightforward method to evaluate zinc reactivity. |
| Note de contenu : |
- MATERIALS AND METHODS : Materials - Determination of free alkalinity - Humid supercritical carbon dioxide exposure - Quantification of oxidized zinc - Cleaning and pretreatment - Surface characterizations
- RESULTS : Effect of free alkalinity on Al2O3 removal - Exposure of cleaned HDG samples to humid scCO2 - Distribution of pretreatment chemical on cleaned samples |
| DOI : |
10.1007/s11998-019-00272-9 |
| En ligne : |
https://link.springer.com/content/pdf/10.1007/s11998-019-00272-9.pdf |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33745 |
in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 17, N° 1 (01/2020) . - p. 285-292
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