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Chrome - free single - step in - situ phosphatizing coatings on a ti - 6al - 4v titanium alloy / Heather Neuder in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 74, N° 930 (07/2002)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 74, N° 930 (07/2002) . - p. 37-42 Titre : Chrome - free single - step in - situ phosphatizing coatings on a ti - 6al - 4v titanium alloy Type de document : texte imprimé Auteurs : Heather Neuder, Auteur ; Chhiu-Tsu Lin, Auteur Année de publication : 2002 Article en page(s) : p. 37-42 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 667.9 Revêtements et enduits Résumé : Surface pretreatment, such as chromate conversion, is generally required for the organic coating on Ti-6Al-4V titanium alloys. The surface modification process facilitates bond formation between the titanium surface and adhesives or paints. However, the hexavalent chromate used in the conversion coating is carcinogenic and must be eliminated. Recently, the “green chemistry” technique of in-situ phosphatizing coatings (ISPC) has been developed at Northern Illinois University. In this study, a polyester-melamine coating system catalyzed by p-toluene sulfonic acid is used as a control paint and applied to bare (paint 1) and chromated (paint 3) Ti alloy panels. The arylphosphonic acid employed as an in-situ phosphatizing reagent (ISPR) is used to formulate ISPC polyester-melamine paint and to react in-situ with the metal surface when ISPC paint is applied on bare Ti panels (paint 2) and chromated Ti panels (paint 4). After soaking in 3% NaCl solution for 1500 hr, the electrochemical impedance, |Z|, was measured as 109, 1010, 1010, and 1010 ohm-cm2 for paints, 1, 2, 3, and 4, respectively. After 1000 hr salt spray (fog) testing, a disbondment from the “X” scribe is observed as 13 and <0.5, <1, <1 mm for paints 1, 2, 3, and 4, respectively. The simultaneous reaction of the ISPR in catalyzing the polymerization of paint film and forming the metal-phosphate layer is the reason for the superior ISPC paint performance. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5636 [article]

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Durability of powder-coated hot-dip galvanized steel / H. G. J. M. Verstappen in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 74, N° 930 (07/2002)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 74, N° 930 (07/2002) . - p. 43-54 Titre : Durability of powder-coated hot-dip galvanized steel Type de document : texte imprimé Auteurs : H. G. J. M. Verstappen, Auteur ; S. J. van Susteren, Auteur ; W. J. van Ooij, Auteur Année de publication : 2002 Article en page(s) : p. 43-54 Note générale : Bibliogr. Langues : Américain (ame) Tags : Etude  expérimentale  Durabilité  Zingage  immersion  Acier  galvanisé  Peinture  anticorrosion  poudre  Revêtement  non  métallique  Matériau  revêtement  Protection  corrosion Index. décimale : 667.9 Revêtements et enduits Résumé : In this study, the quality and durability of powder-coated hot-dip galvanized products have been investigated. Standard steel coupons hot-dip galvanized in conventional and delta (i.e., high temperature) conditions were coated with powder paint systems or a high quality solvent-based system and then subjected to a wide range of test methods representing mild or highly aggressive exposure conditions. Additional variables in the project were the silicon content of the steel and the treatment prior to painting. The use of delta-galvanized steel as a base for painting offers a number of advantages such as much greater hardness and improved paint adhesion. Maximum corrosion protection is observed if the galvanized base is treated with chromate and sequentially powder coated with an epoxy primer followed by a polyester topcoat. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5643 [article]

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A selective catalyst for two-component waterborne polyurethane coatings / Z. Alex He in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 74, N° 930 (07/2002)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 74, N° 930 (07/2002) . - p. 31-36 Titre : A selective catalyst for two-component waterborne polyurethane coatings Type de document : texte imprimé Auteurs : Z. Alex He, Auteur ; Werner J. Blank, Auteur ; Marie E. Picci, Auteur Année de publication : 2002 Article en page(s) : p. 31-36 Note générale : Bibliogr. Langues : Américain (ame) Tags : Etude  expérimentale  Zirconium  Complexe  Catalyseur  Adjuvant  Formulation  Peinture  eau  Uréthanne  polymère  deux  constituants  Matériau  revêtement Index. décimale : 667.9 Revêtements et enduits Résumé : The potential for formulating low VOC, high performance, two-component waterborne isocyanate crosslinked coatings has generated a great deal of interest. The difficulties in formulating these coatings, however, are significant. A major problem associated with such systems is the isocyanate-water side reaction, which can lead to gassing/foaming, loss of isocyanate functionality, low gloss, and a reduced pot life. To compensate for this side reaction, these formulations usually contain a large excess of isocyanate. One novel approach to control the water side reaction is the use of catalysts which selectively catalyze the isocyanate-polyol reaction and not the isocyanate-water reaction. The selectivity of a variety of metal catalysts to catalyze the preferred reaction was measured using an FTIR method. A zirconium complex has shown unusually high selectivity for the isocyanate-polyol reaction in comparison to the standard dibutyltin dilaurate catalyst. This zirconium complex catalyst has been evaluated in several waterborne polyurethane formulations and has demonstrated less gassing/foaming, longer pot life, and higher gloss than dibutyltin dilaurate at equal cure time. The mechanism of catalysis and formulating techniques of this novel zirconium catalyst will be discussed. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5644 [article]

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