Evaluation of a Trivalent Chromium Process (TCP) Conversion Coating on AA2024-T3 That Requires No Surface Pretreatment

2019 ◽  
Vol 166 (15) ◽  
pp. C589-C599 ◽  
Author(s):  
Jack Walton ◽  
T. K. Shruthi ◽  
David Yancey ◽  
Paul Vlasak ◽  
Sjon Westre ◽  
...  
Keyword(s):  
Trivalent Chromium ◽  
Conversion Coating ◽  
Surface Pretreatment

scholarly journals Application of Commercial Surface Pretreatments on the Formation of Cerium Conversion Coating (CeCC) over High-Strength Aluminum Alloys 2024-T3 and 7075-T6

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 930
Author(s):  
Juan Jesús Alba-Galvín ◽  
Leandro González-Rovira ◽  
Francisco Javier Botana ◽  
Maria Lekka ◽  
Francesco Andreatta ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Salt Spray ◽  
Aluminum Matrix ◽  
Optical Emission ◽  
High Strength ◽  
Chemical Conversion ◽  
Conversion Coating ◽  
Neutral Salt ◽  
Corrosion Properties ◽  
Surface Pretreatment

The selection of appropriate surface pretreatments is one of the pending issues for the industrial application of cerium-based chemical conversion coatings (CeCC) as an alternative for toxic chromate conversion coating (CrCC). A two-step surface pretreatment based on commercial products has been successfully used here to obtain CeCC on AA2024-T3 and AA7075-T6. Specimens processed for 1 to 15 min in solutions containing CeCl3 and H2O2 have been studied by scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX), glow discharge optical emission spectroscopy (GDOES), potentiodynamic linear polarization (LP), electrochemical impedance spectroscopy (EIS), and neutral salt spray (NSS) tests. SEM-EDX showed that CeCC was firstly observed as deposits, followed by a general coverage of the surface with the formation of cracks where the coating was getting thicker. GDOES confirmed an increase of the CeCC thickness as the deposition proceed, the formation of CeCC over 7075 being faster than over 2024. There was a Ce-rich layer in both alloys and an aluminum oxide/hydroxide layer on 7075 between the upper Ce-rich layer and the aluminum matrix. According to LP and EIS, CeCC in all samples offered cathodic protection and comparable degradation in chloride-containing media. Finally, the NSS test corroborated the anti-corrosion properties of the CeCC obtained after the commercial pretreatments employed.

scholarly journals Trivalent chromium conversion coating formation on aluminium

2015 ◽  
Vol 280 ◽  
pp. 317-329 ◽  
Author(s):  
J.-T. Qi ◽  
T. Hashimoto ◽  
J.R. Walton ◽  
X. Zhou ◽  
P. Skeldon ◽  
...  
Keyword(s):  
Trivalent Chromium ◽  
Conversion Coating ◽  
Coating Formation

Investigation of the Trivalent Chromium Process Conversion Coating as a Sealant for Anodized AA2024-T3

2020 ◽  
Vol 167 (11) ◽  
pp. 111504
Author(s):  
T. K. Shruthi ◽  
Jack Walton ◽  
Sarah McFall-Boegeman ◽  
Sjon Westre ◽  
Greg M. Swain
Keyword(s):  
Trivalent Chromium ◽  
Conversion Coating

Corrosion Behavior of Rare Earth Cerium Based Trivalent Chromium Conversion Coating on Zinc

2014 ◽  
Vol 881-883 ◽  
pp. 1165-1170 ◽  
Author(s):  
Shu Ting Miao ◽  
Sheng Han ◽  
Lifeng Hao
Keyword(s):  
Electron Microscopy ◽  
Corrosion Resistance ◽  
Rare Earth ◽  
Electrochemical Method ◽  
Trivalent Chromium ◽  
Conversion Coating ◽  
Passivation Film ◽  
Good Corrosion Resistance ◽  
Scanning Electron ◽  
Cerium Hydroxide

The present paper focused on the use of the salt of rare earth cerium as corrosion inhibitor of Zinc by using cathodic electrolytic passivation method. The corrosion resistance and the microphology of the cerium passivation film were studied by the methods of electrochemical method, scanning electron microscopy (SEM). From the results, it was shown that good corrosion resistance of cerium-based trivalent chromium conversion coating was obtained when the compositions were as follows: Ce (SO4)2, 6g/L; Cr2(SO4)3, 18.9g/L and NaNO3; current density, 2A/dm2; temperature, 40 oC; time, 60s. SEM revealed that the cerium trivalent chromium conversion coatings formed uniform cerium hydroxide and chrimuim hydroxide deposition on the surface of Zinc.

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