Study on the Self-Repairing Effect of Nanoclay in Powder Coatings for Corrosion Protection

• Published in: Coatings (Basel) 2023-07, Vol.13 (7), p.1220
• Main Authors: Yang, Marshall Shuai, Huang, Jinbao, Zhang, Hui, Noël, James Joseph, Hedberg, Yolanda Susanne, Chen, Jian, Eduok, Ubong, Barker, Ivan, Henderson, Jeffrey Daniel, Xian, Chengqian, Zhang, Haiping, Zhu, Jesse
• Format: Article
• Language: English
• Subjects: Additives; Clay; Corrosion; Corrosion and anti-corrosives; Corrosion effects; Corrosion prevention; Corrosion resistance; Curing; Dosage; Electrochemical impedance spectroscopy; Electrolytes; Graphene; Hazardous air pollutants; Immersion tests (corrosion); Instrument industry; Mechanical properties; Montmorillonite; Particle size; Performance evaluation; Polyesters; Polymers; Powder coatings; Powders; Protective coatings; Salt spray tests; Spectrum analysis; Surface properties; Triglycidyl isocyanurate; VOCs; Volatile organic compounds
• ISSN: 2079-6412; 2079-6412
• DOI: 10.3390/coatings13071220

Powder coatings are a promising, solvent-free alternative to traditional liquid coatings due to the superior corrosion protection they provide. This study investigates the effects of incorporating montmorillonite-based nanoclay additives with different particle sizes into polyester/triglycidyl isocyanurate (polyester/TGIC) powder coatings. The objective is to enhance the corrosion-protective function of the coatings while addressing the limitations of commonly employed epoxy-based coating systems that exhibit inferior UV resistance. The anti-corrosive and surface qualities of the coatings were evaluated via neutral salt spray tests, electrochemical measurements, and surface analytical techniques. Results show that the nanoclay with a larger particle size of 18.38 µm (D50, V) exhibits a better barrier effect at a lower dosage of 4%, while a high dosage leads to severe defects in the coating film. Interestingly, the coating capacitance is found, via electrochemical impedance spectroscopy, to decrease during the immersion test, indicating a self-repairing capability of the nanoclay, arising from its swelling and expansion. Neutral salt spray tests suggest an optimal nanoclay dosage of 2%, with the smaller particle size (8.64 µm, D50, V) nanoclay providing protection for 1.5 times as many salt spray hours as the nanoclay with a larger particle size. Overall, incorporating montmorillonite-based nanoclay additives is suggested to be a cost-effective approach for significantly enhancing the anti-corrosive function of powder coatings, expanding their application to outdoor environments.