Alternative conversion coatings to chromate for the protection of magnesium alloys

Pommiers, Sébastien; Frayret, Jérôme; Castetbon, Alain; Potin‐Gautier, Martine

doi:10.1016/j.corsci.2014.03.021

Cited by 173 publications

(76 citation statements)

References 56 publications

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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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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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“…Phosphate-permanganate treatment, (Pommiers et al, 2014), was used for specimens coating. The cast and heat treated AZ91D specimens were cut into specimens with dimensions of 10 mm × 10 mm × 2 mm.…”

Section: Heat Treatmentmentioning

confidence: 99%

“…The fact that the environmental criteria continue to be stricter contributes to the continuously limited selection of appropriate chemicals applicable to the active Mg surface protection (Zhao et al, 2006). Therefore, the emphasis on rapid development in the field of the conversion coating is observed (Pommiers et al, 2014;Barranco et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Effect of Quench Environment on the Conversion Coatings on Magnesium Alloy AZ91

Ševčíková

Fintová

Wasserbauer

et al. 2018

Acta Univ. Agric. Silvic. Mendelianae Brun.

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The aim of the study is to achieve fine microstructure of AZ91, due to the optimized heat treatment processes, which can be easily coated with a normal conversion process as phosphating. Determination of the influence of the AZ91 microstructure, mainly precipitates which are created using different cooling media during the heat treatment and definition of the best heat treatment process parameters are the main experimental sections of the work. The structure of the samples heat treated under different conditions was subsequently compared with the structure of the as cast state of AZ91. The morphology of the conversion coating was studied by scanning electron microscopy (SEM) and amount of individual elements in the deposited coating was determined by EDS analysis.

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“…Acid etching was a conventionally used pretreatment process to remove the surface oxide and contaminants for the following surface finishing [10][11][12][13][14][15][16] . However, since acid etching of Mg alloys not only leaves thick oxide films on the surface but also do not etch them uniformly, acid etching hardly be used generally as a pretreatment process for the following chemical conversion coating or electrophoretic painting processes.…”

Section: Introductionmentioning

confidence: 99%

A Blade-Abrading Method for Surface Pretreatment of Mg Alloys

Moon¹

2015

Journal of the Korean institute of surface engineering

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A blade-abrading method was newly developed for the preparation of clean Mg alloy surface and reported for the first time in detail in this paper. The blade-abrading method includes abrading of the Mg alloy surface with a sharp blade or knife to remove the surface oxide and contaminants on the skin of Mg alloys mechanically, thereby providing very clean surface of Mg alloys. The clean surface prepared by the blade-abrading method in the air was found to be covered with thin and dense air-formed oxide films. Based on the experimental results obtained in this work, it is concluded that the newly developed blade-abrading technique is a very simple and useful pretreatment method which can provide clean and well-defined surface for the following surface treatments.

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Alternative conversion coatings to chromate for the protection of magnesium alloys

Cited by 173 publications

References 56 publications

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

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

Effect of Quench Environment on the Conversion Coatings on Magnesium Alloy AZ91

A Blade-Abrading Method for Surface Pretreatment of Mg Alloys

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