Effects of SO2 deposition on painted steel surfaces

✍ Scribed by G. D. Davis; B. A. Shaw; C. O. Arah; T. L. Fritz; W. C. Moshier; T. C. Simpson; P. J. Moran; K. L. Zankel

• Book ID: 104592420
• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 476 KB
• Volume: 15
• Category: Article
• ISSN: 0142-2421
• DOI: 10.1002/sia.740150208

✦ Synopsis

Abstract

The effects of 1 ppm SO~2~ with high humidity on alkyd‐painted steel was investigated using x‐ray photoelectron spectroscopy (XPS) and adhesion tensile tests. The SO~2~ caused a spotted discoloration on the specimens on which dew is allowed to dry and accelerated the loss of adhesion between the primer and the steel. The brown spots are characterized by a high S content and form in areas where the condensed dew becomes more concentrated in H~2~SO~3~ or H~2~SO~4~ as it evaporates. Specimens not exposed to dew also have high S concentration on the surface, but do not discolor. High humidity alone caused a loss of adhesion at the primer–metal interface, but SO~2~ increased the rate of this de‐adhesion. Such a loss of adhesion decreases the protection provided by the paint system and the presence of Fe on both sides of some failures indicated that the substrate was beginning to corrode.