Abstract
In this study, a process for depositing hydrotalcite (HT) coatings on galvanized steel was developed and the resulting coatings were characterized. Results showed that coatings formed spontaneously on galvanized surfaces upon exposure to ambient temperature alkaline aluminate solutions. Anodic polarization and electrochemical impedance spectroscopy experiments showed clear evidence of surface passivation. Scanning electron microscopy showed the formation of a continuous and conformal surface film comprised on a compact mass of crystallites. X-ray diffraction confirmed that the coating contained an Al-Zn hydrotalcite compound. Coating formation was enhanced by oxidizer and ammonium salt additions. Coatings formed by using best practices were deposited in less than 10 minutes and demonstrated good surface coverage and good organic coating adhesion. HT coatings formed by using best practices showed excellent organic coating adhesion compared to zinc phosphate control coatings. In salt spray testing, the presence of a hydrotalcite conversion coating under an epoxy neat resin was found to delay the onset of red rusting compared to control samples that were epoxy coated, but not conversion coated.
| Original language | English |
|---|---|
| Pages (from-to) | 277-290 |
| Number of pages | 14 |
| Journal | Journal of Coatings Technology and Research |
| Volume | 1 |
| Issue number | 4 |
| DOIs | |
| State | Published - Oct 2004 |
Bibliographical note
Funding Information:This work was supported by Concurrent Technologies Corporation, Largo, FL under contract no. 030100247, Mr. L. Gintert, program manager.
Keywords
- Accelerated testing
- Adhesion
- Auto-motive-OEM
- Cast iron
- Conversion coating
- Corrosion
- Corrosion protection
- Electrochemical impedance
- Iron
- Phosphate
- Pollution
- Steel
ASJC Scopus subject areas
- General Chemistry
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Colloid and Surface Chemistry