Corrosion Behavior of a Conversion Coating Based on Zirconium and Colorants on Galvanized Steel by Electrodeposition

Costa, Josiane Soares; Agnoli, Raquel Dei; Ferreira, Jane Zoppas

doi:10.4322/2176-1523.0852

Cited by 6 publications

(8 citation statements)

References 22 publications

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“…6,36,37,42,51,52,[55][56][57]61,62,65,68,75,[85][86][87][88]94,98,108,109 although conversion was carried out at pH between 1.5 and 6. 30,32,46,48,49,53,64,66,[68][69][70]77,78,82,90,95,99,106,107,110 More extensive and thicker coating formation at pH 4.0 than at 2.9 was noticed for Gardabond X4707 coating on AA6060. 94 The coating formed at pH 4 showed lower cathodic current density compared to that formed at 2.9.…”

Section: Conversion Bath Parametersmentioning

confidence: 94%

“…TA (2-3 g/L) was added to a mixed Ti/Zr fluoro conversion coating on AA6063 50,61 and galvanized steel. 78 A double layer structure was postulated with metal−organic complexes located primarily in the outer layer of the conversion coating, and an inner layer made mainly of Na 3 Al 6 , TiO 2 , Al 2 O 3 , etc.…”

Section: Conversion Bath Additivesmentioning

confidence: 99%

“…33,34,36,37,47,51,52,55,59,61,62,[64][65][66]69,70,72,78,82,84,87,90,92,94,95,98,99,101,102,104,[106][107][108]110,[112][113][114] Elevated temperatures were also studied, i.e. between 30 and 55…”

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confidence: 99%

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Review—Conversion Coatings Based on Zirconium and/or Titanium

Milošev

Frankel

2018

J. Electrochem. Soc.

156

113

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There is a growing interest in conversion coatings based on titanium and/or zirconium as the result of the health and environmental issues associated with legacy chromate and phosphate conversion coatings. Any alternative technology should be environmentally friendly and cost effective, and also able to achieve comparable corrosion resistance and paint adhesion for ferrous and non-ferrous substrates. Conversion coatings based on titanium or zirconium seem to fulfill many of these requirements and thus offer a great potential for further applications. This literature review summarizes the scientific results in this rapidly growing area of research. Following the description of composition of conversion bath and deposition mechanism, the effects of process parameters for conversion baths such as pH, temperature, immersion time and agitation are presented together with coating characteristics. The effects of the type of substrate and substrate pre-treatment are explored for the most-studied substrates: Al alloys, zinc-coated steels and steels. Properties such as composition, morphology and thickness are summarized. The corrosion performance of the conversion coatings is discussed, as well as adhesion of organic coatings and delamination mechanism for a full coating system including substrate/coating/top-coat. Metals used in the construction of products and facilities in most applications, including industrial, infrastructure, transportation, construction, consumer goods, etc., are primarily selected from three groups: steels, zinc-coated (galvanized) steels, and aluminum alloys (AA).1 All of these materials require protection to prevent environmental degradation, and the most common approach to protection against corrosion is a multilayer coating system. Metal components are treated by a series of processes to create this coating system: cleaning, surface pre-treatment, and application of organic coating layers including primer and topcoat. Surface pre-treatments include anodizing (for aluminum alloys) and conversion coatings, which are the focus of this review. Conversion coatings are formed by immersion of a component in a chemical bath and reaction of the metal substrate with the components in the bath to form a layer that coats the surface. These layers provide some corrosion protection by acting as a barrier to the environment or releasing corrosion-inhibiting species. However, their primary role is to improve the adhesion of subsequently applied paint layers.The most important conversion coatings used for corrosion protection and adhesion promotion of ferrous and non-ferrous metal substrates are chromate conversion coatings (CCCs) and phosphate coatings. CCCs are highly corrosion protective. They consist of a backbone of chromium oxide/hydroxide with Cr in the 3+ oxidation state and also contain compounds with Cr in the 6+ oxidation state. 2-5The Cr(VI) provides the characteristic of self-healing, which is the ability to reform a protective coating after it has been breached by a mechanical or chemical proces...

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Section: Conversion Bath Parametersmentioning

confidence: 94%

Section: Conversion Bath Additivesmentioning

confidence: 99%

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Review—Conversion Coatings Based on Zirconium and/or Titanium

Milošev

Frankel

2018

J. Electrochem. Soc.

156

113

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“…O processo gera efluentes ricos em cromo hexavalente que representam risco em caso de disposição e tratamento inadequados [4]. Mesmo que existam estudos visando o tratamento mais eficiente de poluentes contendo cromo [5], há um esforço global na busca por alternativas ambientalmente mais amigáveis que a cromatização [6], como revestimentos nanocerâmicos [7], revestimentos de conversão à base de terras raras [8], molibdato [9], manganato [10] e revestimentos à base de organossilanos [11], objeto de estudo do presente trabalho.…”

Section: Introductionunclassified

Deposição Eletroassistida De Ortossilicato De Tetraetila (Teos) Como Pré-Tratamento Para a Pintura De Alumínio Aa1100

Moreira¹,

Cardoso²,

Ferreira³

et al. 2018

Tecnologia Em Metalurgia Materiais E Mineração

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ResumoA técnica convencional de produção de filmes de organossilanos por imersão pode promover a formação de pré-tratamentos pouco homogêneos, prejudicando a sua proteção por barreira contra a corrosão e a aderência de tintas. Sendo assim, a técnica de deposição eletroassistida, baseada na promoção da eletrólise da água e consequente favorecimento das reações de condensação do organossilano, é estudada com o objetivo de promover a formação de filmes com menos descontinuidades. Neste trabalho a deposição eletroassistida foi comparada com a técnica convencional de imersão, bem como com a cromatização hexavalente. O precursor utilizado neste trabalho foi o ortossilicato de tetraetila (TEOS), um silano não funcionalizado. A comparação entre os pré-tratamentos foi realizada através de ensaios de corrosão acelerada em névoa salina, medida de aderência de tinta, espectroscopia de impedância eletroquímica e espectroscopia de energia dispersiva. Os resultados indicam que a deposição eletroassistida em potenciais catódicos promoveu maior cobertura do substrato. Palavras-chave: Silano; Deposição eletroassistida; Pré-tratamento; Alumínio. TETRAETHYL ORTHOSILICATE (TEOS) ELECTRO-ASSISTED DEPOSITION AS A PRETREATMENT FOR PAINTING AA1100 ALUMINUM ALLOY AbstractThe standard method for the production of organosilane films by dip-coating may lead to non-homogeneous pretreatment layers, weakening its barrier protection against corrosion and paint adhesion. Therefore, the electro-assisted deposition technique, based on promoting water electrolysis and the consequent favoring of condensation reactions of the organosilane, is studied with the aim of promoting the formation of less discontinuous coatings. In this work the electro-assisted deposition was compared to the standard dip-coating method and to hexavalent chromate conversion coating. The precursor used in this work was tetraethyl orthosilicate (TEOS), a non-functional silane. The comparison between the pretreatments was carried out by salt spray tests, paint adhesion measurement, electrochemical impedance spectroscopy and energy dispersive spectroscopy. The results indicate that the electro-assisted deposition in cathodic potentials promoted higher coverage of the substrate.

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“…Many types of CRM-free coatings based on single-layer or multilayer systems [ 93 , 94 , 95 , 96 , 97 ] or functionally-graded materials represent solutions to drastically reduce the content of Cr and other CRMs, especially for high temperature energy generation [ 98 , 99 ]. Moreover, non-chromate conversion coatings based on nanostructured Zr and/or Ti layers have the advantages of being free of toxic metals or organic compounds and are potential candidates to substitute chromate coatings [ 100 ].…”

Section: Possible Crm-friendly Solutionsmentioning

confidence: 99%

Solutions for Critical Raw Materials under Extreme Conditions: A Review

et al. 2017

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In Europe, many technologies with high socio-economic benefits face materials requirements that are often affected by demand-supply disruption. This paper offers an overview of critical raw materials in high value alloys and metal-matrix composites used in critical applications, such as energy, transportation and machinery manufacturing associated with extreme working conditions in terms of temperature, loading, friction, wear and corrosion. The goal is to provide perspectives about the reduction and/or substitution of selected critical raw materials: Co, W, Cr, Nb and Mg.

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Corrosion Behavior of a Conversion Coating Based on Zirconium and Colorants on Galvanized Steel by Electrodeposition

Cited by 6 publications

References 22 publications

Review—Conversion Coatings Based on Zirconium and/or Titanium

Review—Conversion Coatings Based on Zirconium and/or Titanium

Deposição Eletroassistida De Ortossilicato De Tetraetila (Teos) Como Pré-Tratamento Para a Pintura De Alumínio Aa1100

Solutions for Critical Raw Materials under Extreme Conditions: A Review

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