Growth Kinetics and Structure of Zr4/Cr3 Based Conversion Coating over Aluminium

Thirupathi, Kalaivanan; Bárczy, Pál; Lassú, Gábor

doi:10.24274/fn.2016.a15

Cited by 1 publication

(2 citation statements)

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“…In summary, the conversion coating has a two-phase sol-gel structure that is observed after exposure to vacuum. A similar sol-gel effect has been observed from the depth profiling using glow discharge optical emission spectroscopy (GD-OES) of coated samples that were exposed to high vacuum [16].…”

Section: B Effects Of High Vacuum On Coating Structuresupporting

confidence: 62%

“…This makes the determination of coating thickness using SNMS difficult as compared to other surface analytical methods. The chemistry of the coating surface with dependence of alloying elements will be analysed in our next paper using GD-OES [16]. The effect of ageing has not been studied in detail in this study, but literature indicates that ageing plays a major role in conversion coating behaviour.…”

Section: Influence Of Alloying Elements and Ageingmentioning

confidence: 99%

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Effects of vacuum and ageing on Zr4/Cr3 based conversion coatings on aluminium alloys

Thirupathi

Bárczy

Vad

et al. 2018

Applied Surface Science

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In this study, we investigate the impact of ageing and high vacuum on existing environmentally friendly Zr4/Cr3-based conversion coatings. The freshly formed coating undergoes several changes during ageing and exposure to high vacuum. Based on the present data, we propose that the coating formed over AA6082 and AA7075 alloys is sol-gel in nature, confirmed by secondary neutral mass spectroscopy (SNMS) using the depth profiling technique. Our findings reveal that there are elemental level changes that result in shrinkage of the coating. Most Zr ions in the coating are in the solute form, with lesser number of Cr and Al ions that disappear under high vacuum over a certain period of time. The remaining Cr, Zr and O atoms exist in a gelatinous state. During ageing, there is a continuous transition of ions from solute to gelatinous state. In addition, the deposition of coating ions is directly influenced by the substrates and their constituents. The extent of dissolution of aluminium in the conversion bath determines both Zr and Cr ion deposition. For a highly alloyed metal like AA7075, the dissolution rate is disturbed by copper and zinc.

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Section: B Effects Of High Vacuum On Coating Structuresupporting

confidence: 62%

Section: Influence Of Alloying Elements and Ageingmentioning

confidence: 99%