Formation and characterisation of Ti–Zr based conversion layers on AA6060 aluminium

Lunder, Otto; Simensen, Christian J.; Yu, Yingda; Nisancioḡl̄ū, Kemal

doi:10.1016/j.surfcoat.2003.11.003

Cited by 147 publications

(116 citation statements)

References 9 publications

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“…Grain boundaries have a dark appearance, which indicates strong presence of the pretreatment chemical [27]. Inside the grains there are remarkable contrast variations, which have earlier been shown to depend on the microscale thickness variations within the pretreatment layer [28].…”

Section: Helium Ion Microscopy Of a Pretreated Samplementioning

confidence: 99%

Effect of Hot Dip Galvanized Steel Surface Chemistry and Morphology on Titanium Hexafluoride Pretreatment

Saarimaa¹,

Markkula²,

Arstila³

et al. 2017

AMPC

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Titanium hexafluoride pretreatments are known to improve paint adhesion and function as a barrier between the coating and the hot dip galvanized (HDG) steel surface. Interactions at the zinc/pretreatment interface are of utmost importance for the formation of pretreatment layers and the corrosion resistance of color coated hot dip galvanized steels. Removal rate of inert aluminum oxide from HDG steel samples by chemical dissolution was studied. XPS measurements showed that the surface Al 2 O 3 layer thickness decreased rapidly already at mild alkaline cleaning, while complete removal of Al required severe etching. Low reactivity of an Al 2 O 3 -rich surface was confirmed by impaired formation of a titanium hexafluoride pretreatment layer. Grain boundaries and deformation twinnings were shown to be of importance for the reactivity of the HDG surface and for the precipitation of the pretreatment chemical. Helium ion microscopy images and electron probe microanalysis (EPMA) of a pretreated sample showed accumulation of the pretreatment chemical at the grain boundaries. Al removal rate was fast at the deformation twinnings at the grain plateaus. Slow Al removal was observed at dendritic valleys and grain boundaries. The results increase understanding of the reactivity of hot dip galvanized steel surface.

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Section: Helium Ion Microscopy Of a Pretreated Samplementioning

confidence: 99%

Effect of Hot Dip Galvanized Steel Surface Chemistry and Morphology on Titanium Hexafluoride Pretreatment

Saarimaa¹,

Markkula²,

Arstila³

et al. 2017

AMPC

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“…36,37 In this paper, a nanoceramic pretreatment, which is based on hexafluorozirconic acid, was applied to Al alloy AA6014 in the presence of Cu II in the deposition bath. The structure and morphology of the conversion layer was investigated.…”

mentioning

confidence: 99%

“…[34][35][36] Concerning deposition of nanoceramic conversion coatings, direct evidence has been presented that intermetallic particles act as local cathodes, leading to increased pH in the region of the intermetallic particles, and subsequently to increased deposition of TiO 2 /ZrO 2 -based conversion coatings in the absence of Cu. 36,37 The inhomogeneity of the deposition can be affected by stirring (convection). 37 Because intermetallic particles act as local cathodes, preferential deposition of nanoceramic conversion coatings has been observed near the boundaries of the intermetallics, which limited the formation of a good quality conversion layer in the absence of Cu.…”

mentioning

confidence: 99%

“…36,37 The inhomogeneity of the deposition can be affected by stirring (convection). 37 Because intermetallic particles act as local cathodes, preferential deposition of nanoceramic conversion coatings has been observed near the boundaries of the intermetallics, which limited the formation of a good quality conversion layer in the absence of Cu. 36,37 In this paper, a nanoceramic pretreatment, which is based on hexafluorozirconic acid, was applied to Al alloy AA6014 in the presence of Cu II in the deposition bath.…”

mentioning

confidence: 99%

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Role of Intermetallics and Copper in the Deposition of ZrO₂Conversion Coatings on AA6014

Sarfraz

Posner

Lange

et al. 2014

J. Electrochem. Soc.

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Zirconium oxide based conversion coatings are nickel-free alternatives to trication phosphate coatings. Here, the role of intermetallic inclusions in aluminum alloy AA6014 on the formation of Cu-rich particles inside ZrO 2 -based conversion layers with a film thickness of 25-30 nm was investigated. The role of the intermetallic inclusions on the deposition mechanism was characterized by varying the immersion time of the substrate and analyzing the coatings by electron microscopy and atomic force microscopy. Statistical analysis on the growth of the copper rich particles showed instantaneous nucleation of these particles, with a subsequent homogeneous inplane growth at constant height. A strong preferential nucleation of the Cu-rich particles on the intermetallic particles was observed, and was attributed to the cathodic nature of the intermetallics. Raman spectroscopy indicated the presence of crystalline CuO and amorphous ZrO 2 in the film. Enhanced layer formation in the vicinity of intermetallic particles was observed. Conversion coatings are widely used to protect metal surfaces from corrosion and to promote the adhesion of subsequently applied organic paints.1 While phosphate-based conversion coatings still have a large range of applications and some aspects of their formation are subject to more recent work, 2,3 current efforts focus on the replacement of conventional, μm thick phosphate and chromate containing systems by thin coatings that results in layers with an average thickness of just few tens of nm, without toxic ingredients. [4][5][6][7] One class of candidates are rare-earth based coatings. 4,6,[8][9][10] Other candidates are nanoceramic conversion coatings, typically containing zirconium or titanium oxides. Such coatings are either deposited on the surface by sol-gel chemistry, or by immersion into a fluoric acidic of Zr/Ti. Nanoceramic coatings have been shown to provide good multi-metal corrosion protection for various substrates including steel, zinc, and Al alloys, [11][12][13][14][15][16][17] and combine good corrosion performance with excellent adhesion properties. 5,[18][19][20][21][22] A lot of work has been specifically focused on investigation of zirconium or titanium based pretreatment on Al alloys. Their basic film formation mechanism is (i) fluoride etching of the oxide layer (which can be replaced by alkaline treatment), 23 (ii) onset of hydrogen evolution reaction, i.e. water reduction with a consequent increase in pH near the interface, and (iii) subsequent precipitation of oxyhydroxides as oxide precursors.24-27 Inclusion of Cu II salts (or alternatively, Fe salts) in the bath has been shown to lead to higher overall growth rate of the film on cold rolled steel compared to the solutions without Cu II . 25,28 Coatings prepared by including copper in the solution were also shown to be thicker and showed enrichment of copper within the conversion film. 25,28 Painted cold-rolled steel pretreated with a Cu-containing ZrO 2 -based coating shows low frequency impedance moduli comparabl...

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“…Isto indica que não é apenas a porosidade do filme que determina o comportamento eletroquímico do substrato, uma vez que ambos apresentaram valores de ângulo de contato próximos, mas também, a formação dos grupos característicos de cada filme, responsáveis pelo efeito barreira, conforme apresentado na Figura 3, ou seja, as reações anódicas e catódicas provenientes da interação entre substrato e pré-tratamento, influenciam de forma significativa o comportamento eletroquímico. Neste caso, a concentração maior do grupo OH (Figura 3b), proveniente do processo de redução do oxigênio para a formação do filme nanocerâmico, pode ter influenciado na variação mais negativa da curva de OCP em relação ao silano, uma vez que o grupo funcional OH, por ser hidrofílico, prejudica o efeito barreira do filme, permitindo o contato do substrato com o meio [26,27]. Por outro lado, o filme a base de silano apresentou comportamento barreira, não apresentando variações significativas no valor de OCP, o que pode estar relacionado, com a baixa concentração do grupo OH, conforme discutido na Figura 3c, permitindo a formação de grupos Si-O-Si, de caráter hidrofóbico e, por conseguinte, responsáveis pela propriedade barreira do filme.…”

Section: Caracterização Dos Pré-tratamentosunclassified

Influência De Três Pré-Tratamento De Superfície Com Posterior Aplicação De Tinta Poliéster Na Resistência a Corrosão Do Aço Aisi 1008

Marcolin¹,

Pederiva²,

Salvador³

et al. 2017

Tecnologia Em Metalurgia Materiais E Mineração

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ResumoO objetivo deste estudo é analisar a influência de diferentes pré-tratamentos de superfície (fosfato, nanocerâmico e silano) na resistência à corrosão do aço AISI 1008, visando uma posterior aplicação da tinta poliéster. Os pré-tratamentos foram depositados sobre o substrato de maneira distinta. O fosfato teve sua aplicação em escala industrial por meio de pulverização em um sistema onde o desengraxe foi realizado ao mesmo estágio da fosfatização. No nanocerâmico utilizou-se o método por imersão com pH controlado em torno de 4,5 em uma solução de ácido hexafluorzircônio. Para o silano utilizou-se o método de dip-coating, para a aplicação dos precursores tetraetoxisilano (TEOS) e 3-(trimetóxisililpropil) metacrilato (MPTS) pré-hidrolizados. As amostras pré-tratadas foram caracterizadas quanto ao comportamento morfológico e eletroquímico. Após a aplicação de tinta poliéster, as amostras foram avaliadas quanto ao seu comportamento mecânico. Os resultados das análises para os pré-tratamentos superficiais e para os sistemas pré-tratamentos + tinta mostraram que o silano apresentou a melhor resistência à corrosão em relação ao sistema nanocerâmico e fosfatização. Palavras-chave: Fosfatização; Silano; Nanocerâmicos; Tinta poliéster; Corrosão. INFLUENCE OF THREE SURFACE PRE-TREATMENTS WITH SUBSEQUENT APPLICATION OF POLYESTER INK IN CORROSION RESISTANCE OF AISI 1008 STEEL AbstractThe objective of this study was to analyze the influence of different surface pre-treatments (phosphate, nano-ceramic and silane) on the corrosion resistance of AISI 1008 steel, with a view to the subsequent application of polyester ink. The pre-treatments were deposited on the substrate in distinct ways. Phosphate was applied on an industrial scale by spraying in a system where degreasing was carried out at the same stage of phosphating. In the nano-ceramic pre-treatment the immersion method was used, with controlled pH of about 4.5 in a solution of hexafluorzirconium acid. For the silane pre-treatment the dip-coating method was used for the application of pre-hydrolysed tetraethoxysilane (TEOS) and 3-(trimethylsilylpropyl) methacrylate (MPTS) precursors. The pre-treated samples were characterized for morphological and electrochemical behavior. After the application of polyester ink, the samples were evaluated for their mechanical behavior. The results for the surface pre-treatments and for the pre-treatment + ink systems showed that silane presented the best corrosion resistance amongst the tested pre-treatments.

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Formation and characterisation of Ti–Zr based conversion layers on AA6060 aluminium

Cited by 147 publications

References 9 publications

Effect of Hot Dip Galvanized Steel Surface Chemistry and Morphology on Titanium Hexafluoride Pretreatment

Effect of Hot Dip Galvanized Steel Surface Chemistry and Morphology on Titanium Hexafluoride Pretreatment

Role of Intermetallics and Copper in the Deposition of ZrO₂Conversion Coatings on AA6014

Influência De Três Pré-Tratamento De Superfície Com Posterior Aplicação De Tinta Poliéster Na Resistência a Corrosão Do Aço Aisi 1008

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Formation and characterisation of Ti–Zr based conversion layers on AA6060 aluminium

Cited by 147 publications

References 9 publications

Effect of Hot Dip Galvanized Steel Surface Chemistry and Morphology on Titanium Hexafluoride Pretreatment

Effect of Hot Dip Galvanized Steel Surface Chemistry and Morphology on Titanium Hexafluoride Pretreatment

Role of Intermetallics and Copper in the Deposition of ZrO2Conversion Coatings on AA6014

Influência De Três Pré-Tratamento De Superfície Com Posterior Aplicação De Tinta Poliéster Na Resistência a Corrosão Do Aço Aisi 1008

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Role of Intermetallics and Copper in the Deposition of ZrO₂Conversion Coatings on AA6014