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Cathodic delaminations of poly(phenyl ether ether ketone) (PEEK) coatings overlaid on zinc phosphate‐deposited steels
Author(s) -
Sugama T.,
Carciello N. R.
Publication year - 1993
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1993.070501004
Subject(s) - peek , materials science , coating , cathodic protection , corrosion , ether , alkali metal , polyether ether ketone , delamination (geology) , zinc , polymer , zinc phosphate , dissolution , layer (electronics) , adhesive , chemical engineering , composite material , metallurgy , organic chemistry , chemistry , electrochemistry , electrode , paleontology , biology , subduction , tectonics , engineering
The melt‐crystallized poly(phenyl ether ether ketone) (PEEK) polymer was overlaid on crystalline zinc phosphate (Zn • Ph) conversion coating‐deposited and nondeposited coldrolled steels at 400°C in air or in N 2 environments. The ability of these coating systems to protect the steel against corrosion was evaluated from the rate of cathodic delamination of the coating layer from the steel. Because the cathodic reaction, H 2 O + 1/2O 2 + 2e − = 2OH − , at the corrosion side of a defect in the coating layer creates a high pH environment at the interfacial boundary between the coating and steel, the magnitude of susceptibility of the interfacial intermediate layers to the alkali‐induced degradation played a key role in suppressing cathodic failure. The lowest level was observed in the N 2 ‐induced PEEK/Zn • Ph/steel joint systems, thereby decreasing the rate of delamination. By contrast, oxidized PEEK induced by air in same joint systems was susceptible to the alkali‐catalyzed hydrolysis. This phenomenon significantly promoted the alkali dissolution of Zn • Ph crystals, reflecting a high rate of delamination. Nevertheless, the introduction of Zn • Ph as interfacial tailoring material into the intermediate layers markedly acted in reducing the cathodic delamination of PEEK/steel joint systems. © 1993 John Wiley & Sons, Inc.