Current status, opportunities and challenges in chemical conversion coatings for zinc

Gao, Zhiqiang; Zhang, Dawei; Li, Yong; Jiang, Sheming; Zhang, Qifu

doi:10.1016/j.colsurfa.2018.03.018

Cited by 59 publications

(45 citation statements)

References 142 publications

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“…18 Contemporary pre-treatments specifically for aluminium alloys are chemical conversion coatings -chromate-or chromium(I-II)-based, zirconium-and titanium-based, and anodization. 19,20,21,22 Finishing procedure is usually phosphating or electrophoretic paint (electro-coating). 23 In past, the most important conversion coatings used for corrosion protection of ferrous and non-ferrous metal substrates are chromate conversion coatings (CCCs) and phosphate coatings.…”

Section: Corrosion Protection and Current Stateof-the-artmentioning

confidence: 99%

Contemporary Modes of Corrosion Protection and Functionalization of Materials

Milošev

2019

ACSi

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Corrosion protection is an important global issue. Corrosion affects all metal materials in industry, infrastructure, civil engineering, transport, biomedicine, etc. causing their deterioration and degradation. Corrosion protection is a necessity which enables the safe and well-functioning of metal structures and devices. In addition to long-term efficiency, corrosion protection should be environmentally and economically acceptable. Growing population with needs on modern and high-tech technologies is boosting consumption of base and rare earth metals. All these issues are putting high demands on area of corrosion protection with the main goal to prolong the lifetime of metal materials, reduce the need for steeply increasing production and thus preserve resources. In this review contemporary modes of corrosion protection of metal materials with the emphasis on copper and aluminium base alloys as one of most important base metals are presented. These include corrosion inhibitors, conversion, sol-gel and hydrophobic coatings. Examples are our research studies over the last decade are presented.

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Section: Corrosion Protection and Current Stateof-the-artmentioning

confidence: 99%

Contemporary Modes of Corrosion Protection and Functionalization of Materials

Milošev

2019

ACSi

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“…The passivation treatment also helps maintain the bright, shiny appearance of a galvanized sheet for a longer time under conditions of outdoor exposure. The surface also dulls in a more uniform fashion if the sheets are passivated [4].…”

Section: Chemical Passivating Treatmentsmentioning

confidence: 99%

“…Next, in the order or increasing thickness, come the iridescent yellows, browns, bronzes, olive drabs and blacks. Physical variations in the metal surface also affect the apparent colour of the coated surface [4][5][6].…”

Section: Chemical Passivating Treatmentsmentioning

confidence: 99%

Post Treatment of Hot Dip Galvanized Steel Sheet- Chromating, Phosphating and other Alternative Passivation Technologies

2019

Journal of Materials Sciences and Applications

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Zinc coatings protect steel from corrosion in two ways, namely, through barrier and galvanic protection. However, zinc itself undergoes and suffers rapid corrosion under conditions involving high moisture and humidity. Under these conditions, moisture accumulation and/or condensation takes place within the folds of the galvanized coils under storage leading to formation of patches of powdery "white rust" or "storage stains". Therefore, traditionally chemical treatments have been imparted to the hot dip galvanized coils/ sheets to provide the zinc coating with a relatively, shortterm corrosion resistance during the transit to the place of application. Conventionally, chromic acid based treatments (termed "chromating") have been employed in the galvanizing industry to passivate the virgin, hot-dipped zinc coating surface by developing complex, insoluble zinc chromate films superficially. However, with the imposition of stringent environmental regulations on the use and discharge of chromium compounds and effluents, considerable amount of research has been recently devoted, the world over, to find alternative technologies for passivation of hot dip galvanized sheet. Some of such treatments comprise phosphating, molybdating and passivation using silicon-based organofuntional compounds called "silanes" and other proprietary organic chemicals. Although, none of these treatments match the effectiveness and potency of a chromate treatment and the protection afforded by it, still they are seen as potentially viable substitutes for passivation and protection of galvanized sheet against white rust in galvanizing community. Besides, most of these emerging treatments are in a fledgling state of research and their application to continuous galvanizing lines needs to be explored sufficiently for them to be considered as suitable replacements to chromating and to be adopted in a hot dip galvanizing line.The present paper starts with a brief introduction to the mechanism of corrosion of zinc and the sacrificial protection of steel in hot dip galvanized coatings, following which, it reviews, in some detail, the inorganic chemical treatments such as chromating and phosphating for the passivation of hot dip galvanized steel sheet. The paper also briefly touches upon some of the recently-researched alternative treatments for the protection and corrosion resistance of zinc coatings on steel.

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“…In generally, the service life of large-scale steel structures, such as the offshore oil production platform facilities, ship hulls and nuclear power plant, are designed to 70~110 years. Due to prolonged exposure to the marine or industrial atmosphere high corrosive environments for a long time, they must be protected by the anticorrosive coating system to further extend the service life [1,2]. At present, the period of anticorrosion coating system is about 25~35 years and protected by the long-acting coating is the most effective and common path In the case of comprehensive consideration of product life cycle, manufacturing cost, maintenance costs and other factors [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Comparative Study on the Corrosion Resistance of Inorganic Zinc-Rich Coating and Thermal-Spray Zinc Coating

Ni¹,

P²,

Zhu³

et al. 2021

Preprint

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The corrosion resistance of two steel coatings (inorganic zinc-rich coating and thermal-spray zinc coating) was studied in detail by using the electrochemical and salt spray test, and the salt spray corrosion thickness was calculated by the time-varying equation established from the mathematical fitting method. The result show that the corrosion mechanism of the two types of coatings was the same that based on the sacrificed of zinc through anodizing phenomenon. The main reason for the difference of corrosion resistance between the two anticorrosive coatings was that the coating density and shielding effect of corrosion products were different. The 7500-hours salt spray test showed that the corrosion rates and microstructure characteristics of both types of zinc coatings were homogeneous on the premise of ensuring coating reliability. The time-varying equation can be used to evaluate the service life of the zinc coatings and judge their corrosion resistance quickly, that providing theoretical support for the maintenance of steel structures as well as the accelerated selection and design of coating formulations.

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Current status, opportunities and challenges in chemical conversion coatings for zinc

Cited by 59 publications

References 142 publications

Contemporary Modes of Corrosion Protection and Functionalization of Materials

Contemporary Modes of Corrosion Protection and Functionalization of Materials

Post Treatment of Hot Dip Galvanized Steel Sheet- Chromating, Phosphating and other Alternative Passivation Technologies

Comparative Study on the Corrosion Resistance of Inorganic Zinc-Rich Coating and Thermal-Spray Zinc Coating

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