Chromate Free Corrosion Resistant Conversion Coatings For Aluminum Alloys
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Chromate Free Corrosion Resistant Conversion Coatings For Aluminum Alloys
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Author :
language : en
Publisher:
Release Date : 1995
Chromate Free Corrosion Resistant Conversion Coatings For Aluminum Alloys written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.
Inorganic polycrystalline hydrotalcite, Li2[Al2(OH)6]2·CO3·3H2O, coatings can be formed on aluminum and aluminum alloys by exposure to alkaline lithium carbonate solutions. This process is conducted using methods similar to traditional chromate conversion coating procedures, but does not use or produce toxic chemicals. The coating provides anodic protection and delays the onset of pitting during anodic polarization. Cathodic reactions are also inhibited which may also contribute to corrosion protection. Recent studies have shown that corrosion resistance can be increased by sealing hydrotalcite coated surfaces to transition metal salt solutions including Ce(NO3)3, KMnO4 and Na2MoO4. Results from these studies are also reported.
Chromate Free Talc Chemical Conversion Coatings For Aluminum Alloys
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Author :
language : en
Publisher:
Release Date : 1993
Chromate Free Talc Chemical Conversion Coatings For Aluminum Alloys written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with categories.
We have found that aluminum alloys exhibit unusual passivity when exposed to alkaline Li-salt solutions. Observed passivity is due to the formation of a polycrystalline Li2[Al2(OH)6]2·CO3·3H2O film on the aluminum surface. This film is persistent in aggressive environments and provides a significant degree of corrosion protection. On this basis, we have developed a simple non-electrolytic method of forming corrosion resistant coatings in alkaline Li-salt solution. This process is procedurally similar to traditional conversion coating methods, offers desirable properties, and has a low toxic hazard. In this paper, coating methods, coating characterization, and coating properties are presented. Results from parallel test performed with a commercial chromate conversion coatings are presented for comparison.
Processing And Properties Of Chromate Free Conversion Coatings On Aluminum
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Author :
language : en
Publisher:
Release Date : 1994
Processing And Properties Of Chromate Free Conversion Coatings On Aluminum written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994 with categories.
Chromate Free Corrosion Resistant Talc Coatings For Aluminum Alloys
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Author :
language : en
Publisher:
Release Date : 1992
Chromate Free Corrosion Resistant Talc Coatings For Aluminum Alloys written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with categories.
Passivity developed by immersion in an alkaline Li salt solution is retained when the Al surface is exposed to an aggressive solution like aerated NaCl. A process for coating Al was developed using a method similar to the chromate conversion process, imparts appreciable corrosion resistance, but does not use or produce hazardous chemicals. Coatings are formed by immersion in 0.1 M Li carbonate solution whose pH is adjusted to 11.5-12.0 by LiOH additions. Immersion times of 1.5 to 90 min were used to produce talc coatings; best time is 15 min. Increased corrosion resistance is obtained if the coating is sealed by elevated temperature treatment in air or distilled water.
Conversion Coatings
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Author : John W. Bibber
language : en
Publisher: Cambridge Scholars Publishing
Release Date : 2019-09-06
Conversion Coatings written by John W. Bibber and has been published by Cambridge Scholars Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-09-06 with Technology & Engineering categories.
This book is a guide to all new and presently existing processes available to chemically modify the surfaces of industrially used metals. The modifications described here will produce hard scratch-resistant surfaces, corrosion-resistant surfaces, and surfaces that will easily accept applied coatings, such as industrial paints. Included in the book are processes for aluminum, magnesium, titanium, iron, copper, and silver and their respective alloys, as well as a number of other metals and their related alloys.
Surface Conversion Of Aluminum And Ferrous Alloys For Corrosion Resistance
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Author :
language : en
Publisher:
Release Date : 2000
Surface Conversion Of Aluminum And Ferrous Alloys For Corrosion Resistance written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with Science categories.
Astm B 117 Screening Of Nonchromate Conversion Coatings On Aluminum Alloys 2024 2219 5083 And 7075 Using Dod Paint Systems
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Author : Brian E. Placzankis
language : en
Publisher:
Release Date : 2003
Astm B 117 Screening Of Nonchromate Conversion Coatings On Aluminum Alloys 2024 2219 5083 And 7075 Using Dod Paint Systems written by Brian E. Placzankis and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Aluminum alloys categories.
This study examines the corrosion resistance of eight nonchromate conversion coatings versus hexavalent chromium-based Alodine 1200S controls on scribed coated test panels of aluminum alloys 2024, 2219, 5083, and 7075. Five representative Department of Defense (DoD) primer/topcoat organic coating systems were evaluated for each of the conversion coating/alloy combinations. The five DoD coating systems were as follows: MIL-PRF-23377 high solid epoxy primer with MIL-PRF-85285 high solid polyurethane topcoat; MIL-PRF-85582cl waterborne epoxy primer with MIL-PRF-85285 topcoat; MIL-PRF-85582nc waterborne epoxy chromium-free formulation primer with MIL-PRF-85285 topcoat; MIL-P-53030 water-reducible epoxy primer with MIL-C-53039 chemical agent resistant, single-component polyurethane topcoat; and MIL-P-53O22 epoxy primer with MIL-C-53039 polyurethane topcoat. Scribed panels were exposed using American Society for Testing and Materials (ASTM) B 117 (neutral salt fog) for 3000 hours and were photographed and measured at 1, 2, and 3 weeks. Subsequent measurements were taken every 500 hours until 3000 hours were reached or until failures from scribe creepback and/or via blistering occurred using method ASTM D 1654. The testing resulted in the following conclusions: pretreatment performance varies among varying alloys; DoD coating systems formulated with chromium +6 (Cr+6) additives provided significantly enhanced corrosion resistance versus coatings without Cr+6; Alodine 5200 and NAVAIR TCP Cr+3 performed best overall in ASTM B 117 salt fog among non-Cr+6-based pretreatments with performance at or near Cr+6-based Alodine 1200S across all alloys and coating systems examined; commercially available Alodine 5200, in conjunction with the chromium-free organic coatings tested in this study, provides a completely chromium-free coating system with good corrosion resistance. (29 tables, 13 figures, 17 refs.).
Astm B 117 Screening Of Nonchromate Conversion Coatings On Aluminum Alloys 2024 2219 5083 And 7075 Using Dod Paint Systems
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Author :
language : en
Publisher:
Release Date : 2003
Astm B 117 Screening Of Nonchromate Conversion Coatings On Aluminum Alloys 2024 2219 5083 And 7075 Using Dod Paint Systems written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with categories.
This study examines the corrosion resistance of eight nonchromate conversion coatings versus hexavalent chromium-based Alodine 1200S controls on scribed coated test panels of aluminum alloys 2024, 2219, 5083, and 7075. Five representative Department of Defense (DoD) primer/topcoat organic coating systems were evaluated for each of the conversion coating/alloy combinations. The five DoD coating systems were as follows: MIL-PRF-23377 high solid epoxy primer with MIL-PRF-85285 high solid polyurethane topcoat; MIL-PRF-85582cl waterborne epoxy primer with MIL-PRF-85285 topcoat; MIL-PRF-85582nc waterborne epoxy chromium-free formulation primer with MIL-PRF-85285 topcoat; MIL-P-53030 water-reducible epoxy primer with MIL-C-53039 chemical agent resistant, single-component polyurethane topcoat; and MIL-P-53O22 epoxy primer with MIL-C-53039 polyurethane topcoat. Scribed panels were exposed using American Society for Testing and Materials (ASTM) B 117 (neutral salt fog) for 3000 hours and were photographed and measured at 1, 2, and 3 weeks. Subsequent measurements were taken every 500 hours until 3000 hours were reached or until failures from scribe creepback and/or via blistering occurred using method ASTM D 1654. The testing resulted in the following conclusions: pretreatment performance varies among varying alloys; DoD coating systems formulated with chromium +6 (Cr+6) additives provided significantly enhanced corrosion resistance versus coatings without Cr+6; Alodine 5200 and NAVAIR TCP Cr+3 performed best overall in ASTM B 117 salt fog among non-Cr+6-based pretreatments with performance at or near Cr+6-based Alodine 1200S across all alloys and coating systems examined; commercially available Alodine 5200, in conjunction with the chromium-free organic coatings tested in this study, provides a completely chromium-free coating system with good corrosion resistance. (29 tables, 13 figures, 17 refs.).
Magnesium Technology 2011
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Author : Wim H. Sillekens
language : en
Publisher: John Wiley & Sons
Release Date : 2011-04-12
Magnesium Technology 2011 written by Wim H. Sillekens and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-04-12 with Technology & Engineering categories.
The Magnesium Technology Symposium, which takes place every year at the TMS Annual Meeting & Exhibition, is one of the largest yearly gatherings of magnesium specialists in the world. Papers are presented in all aspects of the field, ranging from primary production to applications to recycling. Moreover, papers explore everything from basic research findings to industrialization. Magnesium Technology 2011 covers a broad spectrum of current topics, including alloys and their properties; cast products and processing; wrought products and processing; forming, joining, and machining; corrosion and surface finishing; ecology; and structural applications. In addition, you'll find coverage of new and emerging applications in such areas as biomedicine and hydrogen storage.
Environmentally Compliant Corrosion Resistant Electrically Conductive Inorganic Coatings For Aluminum Alloys
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Author :
language : en
Publisher:
Release Date : 2001
Environmentally Compliant Corrosion Resistant Electrically Conductive Inorganic Coatings For Aluminum Alloys written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
The objective of this project was to develop an environmentally compliant conversion coating for use on aerospace aluminum alloys (e.g., AA2024-T3). This conversion coating was to replace the current chromate conversion coating processes in both mode of application (bath or spray applied in the depot) and function (stand alone corrosion protection, adhesion to organic layers, self-healing, and low electrical contact resistance). Hydrotalcite (HT) was developed within this program as a replacement to chromate conversion coatings. HT coatings are formed by exposure of aluminum and its alloys to alkaline lithium salt solutions. The coating chemistry used to form these conversion coatings has many processing variables (e.g., time, temperature, anion, etc.). A Fractional Factorial Design was used to determine that temperature was one the more critical processing variables. The FFD study also determined that HT coatings formed from nitrate-based chemistries had consistently better stand-alone corrosion protection properties. Through the use of additional oxidants within the coating bath, HT coatings with the ability to withstand 168 hours of salt spray could be formed in less than 6 min. HT conversion coatings could also be post-treated (e.g., hydrothermally aged, surfactant) to revert the hydrotalcite to aluminum oxide, or augmented to include high valence-state rare earth cations (e.g., cerium). Hydrothermal aging allowed a procedure to chemically anodize aluminum, while incorporation of cerium into the molecular gallery of the hydrotalcite structure provided a means to develop self-healing characteristics, a highly sought property characteristic of chromate-based coatings. Self- healing was indeed demonstrated by the cerium doped HT coatings. The adhesion of epoxy coatings to the hydrotalcite coating was studied in detail. The Lewis-base nature of HTs makes them intrinsically less able to be wet by the Lewis- base nature of epoxy.