Bonding Properties between Hot-Dip Coated Steel Strip and Polyethylene in Corrugated Pipe

Abstract

We studied the effects of different types of hot-dip coatings and passivation treatments on cross-sectional morphology, adhesion to polyethylene (PE), and bonding energy. The results revealed that the bonding force of a hot-dip Zn–Al coating on a steel strip to PE is 196.3 N. The adhesion of Zn–Al and Zn–Al–Mg to PE before passivation was increased by 84.6% and −31.1% higher than that of Zn and PE. After passivation, the adhesion of Zn–Al and Zn–Al–Mg to PE was increased by 63.8% and −46.6% higher than that of Zn and PE, respectively. Passivation treatment can effectively improve the bonding between hot-dip coatings and PE. The bonding strengths of the hot-dipped Zn, Zn–Al, and Zn–Al–Mg to PE increased by 73.3%, 26.6%, and 33.3%, respectively, following passivation. The application of a silane coupling agent to the passivator formed chemical bonds on the surface of the hot-dip coatings, which improved the adhesion between the coatings and resin. Overall, utilising a hot-dip Zn–Al coating instead of a pure zinc coating (containing 0.01% Al) can improve the adhesion between the coating and PE in steel-strip-reinforced PE spiral-corrugated pipe (MRP), thereby improving the application performance of the MRP.