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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