A study of diffusional zinc and aluminum- and zinc-based coatings on steel
- Univ. del Zulia, Maracaibo (Venezuela). Centro de Estudios de Corrosion
This article presents a study of aluminum (Al)- and zinc (Zn)-based diffusional metallic coatings on small, irregularly shaped pieces of carbon steel (CS). The Zn sherardized coating was applied in a purpose-built rotary oven, while the Al coating was laid on by cementing with halide-activated powders (pack cementation). The Al samples were coated with Zn to produce the Al-on-Zn (Al/Zn) coatings. Several techniques were used to characterize the coatings, such as: metallographic analysis, semi-quantitative morphological analysis of the different components, and thicknesses using scanning electron microscopy and micro-hardness tests. A comparative study of resistance to atmospheric corrosion was also carried out on the coatings. The samples that were exposed in a Venezuelan coastal testing station were catalogued as having one of the most aggressive atmospheres in the world (> C5 as per ISO 9223 for CS). It was found that the best iron-on-Zn coating (Fe/Zn) was produced at 350 C with a 3 1/2-h application time. The optimum temperature for the Al/Zn coating was 360 C with a 4-h application time. It was also determined that Zn and Al/Zn diffusional coatings on steel contribute significantly to its resistance to atmospheric corrosion, compared with galvanized steel.
- OSTI ID:
- 495310
- Journal Information:
- Materials Performance, Vol. 36, Issue 6; Other Information: PBD: Jun 1997
- Country of Publication:
- United States
- Language:
- English
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