a comparative study of the 0.05al process october 2, 2012
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A Comparative Study of the 0.05Al ProcessOctober 2, 2012
Background
Al for broadband Si reactivity control
H. Guttman and P. Niessen, 1975
M. Pierre, 1975
Commercialization failure of Polygalva, 1979
Al-compatible flux (G-flux)
US Patent US 7,811,389 B2, 2010
Commercial production of 12Al coating
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Parts
Steel Parts (2982 kg in total)
0.04% - 0.28% Effective Si
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Baths, Centrifuge and Products
Baths (2400 kg each)
Bath A: 0.039%Al
Bath B: 0.051%Al
Bath H: 0.005%Al
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Pretreatments
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Degrease 20 minutes Pickle 20 minutes Rinse 1 minute
Flux 1 minuteDry 120ºC 15 minutes
Coating Thickness (4 minutes)
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450ºC (842ºF), 4 minutes
Coating Thickness (Prior Study)
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440ºC (824ºF), 8 minutes
Coating Thickness (10 minutes)
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450ºC (842ºF), 10 minutes
Coating Adhesion (Part e3)
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Bath B, 10 min
Bath B, 4 minBath H, 4 min
Bath A, 4 min
Microstructure (Part e3, 0.21%Si)
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Bath B, 10 min
Bath B, 4 minBath H, 4 min
Bath A, 4 min
ζ
δ
Flaked-off Coating
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Bath B, 10 min
Bath H, 4 minBath H, 4 min
Bath A, 4 min
Coating Adhesion (Part a)
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Bath H, 4 min
Bath B, 10 min
Bath A, 4 min
Microstructure (Part a, 0.24%Si)
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Bath H, 4 min
Bath B, 10 min
Bath A, 4 min
Zinc Consumption
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Bath AB Bath H
Coating 2.48% 2.97%
Dross 4.81% 4.11%
Ash 1.38% 1.35%
Total 8.67% 8.43%
Drainage (Part k)
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The amount of accumulation at the bottom of Part k:
Bath W (g) W (lb)
H 3.9 0.0086
A 3.0 0.0066
B 2.9 0.0064
Student’s test indicated that there were significant differences between Baths H and AB, whereas there was no significant difference between Baths A and B.
White Rust Test
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H08 B132
Summary
New Process (0.04-0.05%Al) vs. HDG
Al-compatible flux (G-Flux)
Brighter, shinier and thinner coating
Improved coating adhesion
Slightly better drainage
Slightly more dross but same amount of ash
Less visible oxide skin
More localized white rust
Slightly shorter kettle life
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Questions?
Thank you for your attention!
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