Technical Note:Corrosion Protection of Electrogalvanized Steel by a Cerium-Based Conversion Coating

CORROSION ◽  
2006 ◽  
Vol 62 (12) ◽  
pp. 1067-1073 ◽  
Author(s):  
Y-K. Song ◽  
F. Mansfeld
Keyword(s):  
Conversion Coating ◽  
Electrogalvanized Steel

Evaluation of the Growth Mechanism of Ti-Containing Conversion Coatings Using XPS

2015 ◽  
Vol 227 ◽  
pp. 159-162 ◽  
Author(s):  
Wlodzimierz Tylus ◽  
Juliusz Winiarski ◽  
Bogdan Szczygieł
Keyword(s):  
Chemical Composition ◽  
Deposition Time ◽  
Fold Increase ◽  
Weak Acid ◽  
Conversion Coating ◽  
Mechanical Resistance ◽  
Time Interval ◽  
Conversion Coatings ◽  
Electrogalvanized Steel ◽  
Mechanical Properties And Corrosion

Ti-containing coatings as chromate replacement were prepared on electrogalvanized steel. Zinc coatings were deposited from a weak acid chloride bath. Cr-free conversion coatings were deposited from bath composed of: TiCl3, H2SiF6, H2O2 and oxalic acid. XPS was used to evaluate chemical composition of the coatings as a function of deposition time. Deposited coating were of conversion type. Regardless of the achieved conversion coating thickness, Zn from the substrate was always present. In the coatings were identified: Zn2SiO4 / Zn4Si2O7(OH)2, ZnTiO3, ZnO, Zn (OH)2, Zn0, SiOx and Ti-O-Si in varying proportions. The chemical composition of the outer surface of the coating depended on deposition time, e.g. in a time interval 0-300 s 30 fold increase of the Si:Ti ratio and 20 fold of the Si:Zn ratio were observed. Estimated thickness of conversion coating was 3, 14, 35, and 100 nm for the time deposition of 1, 40, 80 and 300 s respectively. It is the proposed model for distinguishing Zn (0) phase from Zn (2+) quantitatively, based on the Zn L3M45M45 spectrum. The composition of the ZnTiSi conversion coating determined its mechanical properties and corrosion resistance. Standard tests carried out showed that the coatings obtained at the time of 20-40 s had the best corrosion performance and mechanical resistance

A vanadium-based conversion coating as chromate replacement for electrogalvanized steel substrates

2011 ◽  
Vol 509 (2) ◽  
pp. 503-507 ◽  
Author(s):  
Zhongli Zou ◽  
Ning Li ◽  
Deyu Li ◽  
Haiping Liu ◽  
Songlin Mu
Keyword(s):  
Conversion Coating ◽  
Electrogalvanized Steel ◽  
Steel Substrates ◽  
Chromate Replacement

Microstructure of Trivalent Chromium Conversion Coating on Electrogalvanized Steel Plate

2008 ◽  
Vol 11 (8) ◽  
pp. C47 ◽  
Author(s):  
N. T. Wen ◽  
F. J. Chen ◽  
M. D. Ger ◽  
Y. N. Pan ◽  
C. S. Lin
Keyword(s):  
Steel Plate ◽  
Trivalent Chromium ◽  
Conversion Coating ◽  
Electrogalvanized Steel

Development of environmentally friendly nonchrome conversion coating for electrogalvanized steel

2004 ◽  
Vol 188-189 ◽  
pp. 762-767 ◽  
Author(s):  
Hyung-Joon Kim ◽  
Jinming Zhang ◽  
Roe-Hoan Yoon ◽  
Richard Gandour
Keyword(s):  
Environmentally Friendly ◽  
Conversion Coating ◽  
Electrogalvanized Steel

scholarly journals Design and Multidimensional Screening of Flash-PEO Coatings for Mg in Comparison to Commercial Chromium(VI) Conversion Coating

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 337
Author(s):  
Ewa Wierzbicka ◽  
Marta Mohedano ◽  
Endzhe Matykina ◽  
Raul Arrabal
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Conversion Coating ◽  
Neutral Salt ◽  
Chromium Vi ◽  
Alkaline Electrolytes ◽  
Az31b Alloy ◽  
Plasma Electrolytic

REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulations demand for an expedient discovery of a Cr(VI)-free alternative corrosion protection for light alloys even though the green alternatives might never be as cheap as current harmful technologies. In the present work, flash- plasma electrolytic oxidation coatings (FPEO) with the process duration < 90 s are developed on AZ31B alloy in varied mixtures of silicate-, phosphate-, aluminate-, and fluoride-based alkaline electrolytes implementing current density and voltage limits. The overall evaluation of the coatings’ anticorrosion performance (electrochemical impedance spectroscopy (EIS), neutral salt spray test (NSST), paintability) shows that from nine optimized FPEO recipes, two (based on phosphate, fluoride, and aluminate or silicate mixtures) are found to be an adequate substitute for commercially used Cr(VI)-based conversion coating (CCC). The FPEO coatings with the best corrosion resistance consume a very low amount of energy (~1 kW h m−2 µm−1). It is also found that the lower the energy consumption of the FPEO process, the better the corrosion resistance of the resultant coating. The superb corrosion protection and a solid environmentally friendly outlook of PEO-based corrosion protection technology may facilitate the economic justification for industrial end-users of the current-consuming process as a replacement of the electroless CCC process.

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.

Sign in / Sign up

Export Citation Format

Share Document