AbstractTo enhance the performance of high‐temperature polyphenylene sulfide (PPS) coating in protecting steels from corrosion, the cold‐rolled steel surfaces were prepared with anhydrous zinc phosphate (Zn · Ph) conversion coatings containing poly(acid) anhydride as an interfacial tailoring material. The factors contributing to the formation of a good bond at the PPS/Zn · Ph joints were as follows: (1) the chemical reaction of PPS with Fe2O3in the Zn · Ph layers, (2) PPS‐to‐poly(acid) anhydride interaction, and (3) the mechanical interlocking between PPS and the rough Zn · Ph crystal surfaces. Although such interfacial bond structures provide a superior durability of PPS/Zn · Ph joints against a hot H2SO4solution, the cathodic reaction, H2O + ½O2+ 2e−= 2OH−, occurring at any defect in the PPS/Zn · Ph joint system when NaCl is present will lead to the delamination of the PPS film from the phosphated steel. This cathodic delamination was due mainly to alkali‐induced dissolution of Zn · Ph layers. However, the rate of delamination for the PPS/Zn · Ph systems was considerably lower compared with that for the PPS/steel system in
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