Corrosion Performance of Epoxy Powder-Coated DD12 Steel with Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments

Mustafa Yiğit Dayınlarlı; Abdülkerim Gök

doi:10.54287/gujsa.1760258

Corrosion Performance of Epoxy Powder-Coated DD12 Steel with Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments

Abstract

Corrosion poses a significant challenge in many industries. Among the various methods for corrosion protection, conversion coatings and powder coatings are widely adopted due to their effectiveness and cost-efficiency. Conversion coatings not only enhance corrosion resistance but also prepare the surface for subsequent finishing processes. In this study, two types of conversion coatings, iron phosphate and zirconium-based, were applied to DD12 steel substrates. Following the coating process, samples were finished with electrostatic powder coating and subjected to two industry-standard corrosion tests: the ISO 9227 neutral salt spray test (up to 400 hours) and the VDA 233-102 cyclic corrosion test (up to three weeks). Samples treated with iron phosphate coatings had thinner and less uniform paint layers compared to those with zirconium-based treatments. Scanning electron microscopy revealed that iron phosphate coatings form larger, irregular grains, while the zirconium-based coatings produced finer and more evenly distributed grains. These structural differences influenced performance: samples with iron phosphate coatings showed better corrosion resistance and paint adhesion during the salt spray test but performed worse in the cyclic test. In contrast, samples with zirconium-based coatings exhibited superior performance in the VDA test but were less effective in the NSS test, suggesting a lower ability to maintain protective qualities under constant salt exposure. Contact angle measurements indicated that zirconium-based coatings led to lower angles, pointing to higher surface energy and potentially stronger adhesion between the powder coating and the metal surface. Cross-sectional SEM images reinforced these results, showing more significant cracking and corrosion in the iron phosphate-coated samples, whereas the zirconium-treated samples had far fewer such defects.

Keywords

References

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Details

Primary Language

English

Subjects

Corrosion

Journal Section

Research Article

Authors

Mustafa Yiğit Dayınlarlı
0009-0004-8268-1985
Türkiye

Abdülkerim Gök ^*
0000-0003-3433-7106
Türkiye

Publication Date

December 31, 2025

Submission Date

August 7, 2025

Acceptance Date

September 24, 2025

Published in Issue

Year 2025 Volume: 12 Number: 4

DOI

https://doi.org/10.54287/gujsa.1760258

IZ

https://izlik.org/JA37MB49HP

Cite

RIS / Bibtex

APA

Dayınlarlı, M. Y., & Gök, A. (2025). Corrosion Performance of Epoxy Powder-Coated DD12 Steel with Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments. Gazi University Journal of Science Part A: Engineering and Innovation, 12(4), 966-978. https://doi.org/10.54287/gujsa.1760258

AMA

1.Dayınlarlı MY, Gök A. Corrosion Performance of Epoxy Powder-Coated DD12 Steel with Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments. GU J Sci, Part A. 2025;12(4):966-978. doi:10.54287/gujsa.1760258

Chicago

Dayınlarlı, Mustafa Yiğit, and Abdülkerim Gök. 2025. “Corrosion Performance of Epoxy Powder-Coated DD12 Steel With Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments”. Gazi University Journal of Science Part A: Engineering and Innovation 12 (4): 966-78. https://doi.org/10.54287/gujsa.1760258.

EndNote

Dayınlarlı MY, Gök A (December 1, 2025) Corrosion Performance of Epoxy Powder-Coated DD12 Steel with Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments. Gazi University Journal of Science Part A: Engineering and Innovation 12 4 966–978.

IEEE

[1]M. Y. Dayınlarlı and A. Gök, “Corrosion Performance of Epoxy Powder-Coated DD12 Steel with Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments”, GU J Sci, Part A, vol. 12, no. 4, pp. 966–978, Dec. 2025, doi: 10.54287/gujsa.1760258.

ISNAD

Dayınlarlı, Mustafa Yiğit - Gök, Abdülkerim. “Corrosion Performance of Epoxy Powder-Coated DD12 Steel With Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments”. Gazi University Journal of Science Part A: Engineering and Innovation 12/4 (December 1, 2025): 966-978. https://doi.org/10.54287/gujsa.1760258.

JAMA

1.Dayınlarlı MY, Gök A. Corrosion Performance of Epoxy Powder-Coated DD12 Steel with Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments. GU J Sci, Part A. 2025;12:966–978.

MLA

Dayınlarlı, Mustafa Yiğit, and Abdülkerim Gök. “Corrosion Performance of Epoxy Powder-Coated DD12 Steel With Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments”. Gazi University Journal of Science Part A: Engineering and Innovation, vol. 12, no. 4, Dec. 2025, pp. 966-78, doi:10.54287/gujsa.1760258.

Vancouver

1.Mustafa Yiğit Dayınlarlı, Abdülkerim Gök. Corrosion Performance of Epoxy Powder-Coated DD12 Steel with Iron Phosphate and Zirconium-Based Conversion Coating Pretreatments. GU J Sci, Part A. 2025 Dec. 1;12(4):966-78. doi:10.54287/gujsa.1760258