Corrosion resistance of chromium-free conversion coatings deposited on electrogalvanized steel from potassium hexafluorotitanate(IV) containing bath

Winiarski, J.; Masalski, J.; Szczygieł, B.

doi:10.1016/j.surfcoat.2013.09.056

Cited by 30 publications

(20 citation statements)

References 27 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: 93%

“…To adjust the pH, different acids can be added, usually phosphoric, [29][30][31][32] but also boric 33 and nitric acid. [34][35][36][37] NaOH or HCl may also be added.…”

Section: Composition Of Zr-and Ti-based Conversion Bathsmentioning

confidence: 99%

“…81 The majority of Zr/Ti based conversion coatings are in the category of thin coatings, between 10 nm and 50-80 nm. 6,[32][33][34]44,49,52,76,77,88,90,91,97,102,105,106,108,112 Coatings with thickness between 100 nm and 600 nm were reported as well, 48,81,94,127 and even in the micrometer thickness range from 1.0 μm up to 6 μm. 30,37,43,59,61,80,119,127 Thickness is related to other parameters such as substrate, pH, time of immersion and stirring, as discussed in Conversion bath parameters and Effect of substrate on coating formation sections.…”

Section: C137mentioning

confidence: 99%

“…32,35,43,58,96 The optimal conditions were different for different coatings. On HDG and Galfan coated steel, 40…”

mentioning

confidence: 99%

“…57 Some Zr/Ti conversion coatings contain phosphates. [29][30][31][32]36,37,54,67,72,102,104,111 Along with the deposition of oxide, hydroxide and fluoride compounds, phosphates can be also formed during conversion process. 30 [11] In this sense, V 5+ ions act similar to Cr 6+ ions.…”

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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.

155

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: 93%

“…To adjust the pH, different acids can be added, usually phosphoric, [29][30][31][32] but also boric 33 and nitric acid. [34][35][36][37] NaOH or HCl may also be added.…”

Section: Composition Of Zr-and Ti-based Conversion Bathsmentioning

confidence: 99%