Zinc-rich polyester powder coatings with iron Phosphide: Lower zinc content and higher corrosion resistance

Jinbao Huang, Marshall Yang, Wenhao Zhu, Keyong Tang, Jian Chen, James Joseph Noël, Haiping Zhang, Liqin Wang, Hui Zhang, Jesse Zhu

Research output: Journal PublicationArticlepeer-review


Many conductive fillers such as carbon black, carbon nanotube and graphene, have been developed to reduce zinc content for zinc-rich coatings, but very few of them could reduce zinc content by 10 % while maintaining the original corrosion protection ability. The carbon-based conductive additives have the issue of corrosion promotion after cathodic protection. In this study, low-cost iron based conductive additive, iron phosphide was used to reduce zinc content in environmentally friendly zinc-rich polyester powder coatings. We investigated the anti-corrosive performance of the prepared coatings by open circuit potential, electrochemical impedance spectroscopy measurements and neutral salt spray tests. The corrosion products were analyzed with Raman spectroscopy, X-ray diffraction and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy. It was found that iron phosphide, due to its conductive nature, inert chemistry, activation function and barrier effect of the lamellar shape, can establish cathodic protection at a low zinc content of 45 wt% with an active protection period of 20 days. It can replace 10 wt% of zinc in 75 wt% zinc-rich polyester powder coatings while maintaining the original cathodic protection ability, as long as 86 days for a 40 μm film. In addition, iron phosphide can significantly inhibit localized corrosion and decrease corrosion creepage by about 20 % during 2500 h salt spray tests. Moreover, a possible corrosion protection mechanism for iron phosphide in zinc-rich polyester coatings was proposed.

Original languageEnglish
Pages (from-to)577-587
Number of pages11
JournalJournal of Industrial and Engineering Chemistry
Publication statusAccepted/In press - 2024
Externally publishedYes


  • Corrosion acceleration
  • Decreased zinc content
  • Iron phosphide
  • Powder coatings
  • Zinc-rich

ASJC Scopus subject areas

  • General Chemical Engineering


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