(2) Corrosion at cross sections of coating layer
Photo-7 shows cross sections of coating layer after 10-year atmospheric exposure test.
(See page 16-17)
Table-7 shows the condensation of results:
a) Singapore: Coating layer of W.R.Alstar has not corroded much and remains in good condition. As to 55% Al-Zn, Zn-rich layer (phase) in coating layer has corroded and some blisters of the coating layer noted. As to Galvanized, zinc coating layer has completely vanished.
b) Manila: Coating layer of W.R.Alstar has not corroded much and remains in good condition. As to 55% Al-Zn, Zn-rich layer (phase) in coating layer has corroded and some blisters of the coating layer noted. With Galvanized, much of the zinc coating layer has vanished.

Table-7. Evaluation of corrosion at cross sections of coating layer after 10-year atmospheric exposure tests.




Photo-7-1. Cross section of several coated steel sheet after 10-year atmospheric exposure tests

Photo-7-2. Cross section of several coated steel sheet after 10-year atmospheric exposure tests



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