Initially,arelatively high corrosionloss is observed for Galvalume sheetas
the zinc-rich portion of the coatingc orrodesa nd provides sacrificial
protection at cut edges. This takes place in all environments, whereas,
aluminum provides adequate galvanic protection only in marinec hloride
TABLE 7.12
Comparison of Cathodic Protection for Galfan and Galvanized
Coatings
Amount (mm) of Bare Edges Exposed after 3
Years (Coating Recession from Edge)
Environment
Galvanized
Galfan
Severemarine
1.6
0.1
Marine
0.5
0.06
Industrial
0.5
0.05
Rural
0.1
0
Source:F romF .C. Porter.1 994. Corrosion Resistance of Zinc and Zinc Alloys,
New York: Marcel Dekker.
20
10
15
5
0
12
24
36
48
60
72
84
96
Exposure time (months)
o=Galvanized
x=Galfan
1-side thickness loss (μm)
FIGURE 7.16
Seven year exposureo fGalfan and galvanized steel in aseverem arine atmosphere.
Coatings
449
CAT8247—CHAPTER 7—17/10/2006—15:03—TRGANESH—XMLM ODEL B–pp. 403–485
the zinc-rich portion of the coatingc orrodesa nd provides sacrificial
protection at cut edges. This takes place in all environments, whereas,
aluminum provides adequate galvanic protection only in marinec hloride
TABLE 7.12
Comparison of Cathodic Protection for Galfan and Galvanized
Coatings
Amount (mm) of Bare Edges Exposed after 3
Years (Coating Recession from Edge)
Environment
Galvanized
Galfan
Severemarine
1.6
0.1
Marine
0.5
0.06
Industrial
0.5
0.05
Rural
0.1
0
Source:F romF .C. Porter.1 994. Corrosion Resistance of Zinc and Zinc Alloys,
New York: Marcel Dekker.
20
10
15
5
0
12
24
36
48
60
72
84
96
Exposure time (months)
o=Galvanized
x=Galfan
1-side thickness loss (μm)
FIGURE 7.16
Seven year exposureo fGalfan and galvanized steel in aseverem arine atmosphere.
Coatings
449
CAT8247—CHAPTER 7—17/10/2006—15:03—TRGANESH—XMLM ODEL B–pp. 403–485