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Lin B.,Tsinghua University | Lu X.,Tsinghua University | Li L.,Guangdong Sanhe Pipe Pile Co.
Journal Wuhan University of Technology, Materials Science Edition | Year: 2011

Arc sprayed Zn and Zn15Al coatings were chosen to protect the metal ends of prestressed high-strength concrete (PHC) pipe piles against corrosion of salina soil in northern china and neutral meadow soil in northeast China. The corrosion behavior of the coated Q235 steel samples in two simulated soil solutions were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The experimental results show that the corrosion of the matrix Q235 steel in both simulated solutions is remarkably inhibited by Zn and Zn15Al coatings. The corrosion products on Zn and Zn15Al are thick, compact, firm and protective. The corrosion current density i corr of both Zn and Zn15Al-coated samples is decreased evidently with corrosion time, and the charge transfer resistance R ct is increased greatly. The corrosion resistance indexes of Zn and Zn15Al in simulated neutral meadow soil solution are more outstanding than those in salina soil. The corrosion resistance of Zn15Al in salina soil is slightly superior to that of Zn. When the sprayed coatings are sealed with epoxy resin, the corrosion resistance of the coatings is further enhanced markedly. © Wuhan University of Technology and Springer Verlag Berlin Heidelberg 2011.


Lin B.-L.,Tsinghua University | Lu X.-Y.,Tsinghua University | Li L.,Guangdong Sanhe Pipe Pile Co.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2011

The corrosion rate, electrochemical corrosion and galvanic corrosion behaviors of the end plate and the steel bar at metal end of prestressed high-strength concrete (PHC) pipe pile in simulated solutions of chloride salt soil, salina soil, neutral meadow soil and acid soil were investigated by natural immersion tests, potentiodynamic polarization and electrochemical impedance spectroscopy measurements and galvanic corrosion tests. The results show that the corrosion resistance of the end plate is inferior to that of the steel bar, and in saline soil the corrosion resistance grade of the steel bar is poor. The cathodic processes of the end plate and the steel bar in four simulated soil solutions are controlled by oxygen diffusion. The corrosion products on end plate and steel bar immersed in saline soil are hardly protective. Steel bar is anodic and end plate is cathodic when they were coupled and immersed in four solutions. The galvanic corrosion effect of stell bar in acid soil is maximal, while that in neutral meadow soil is minimal.


Lin B.-L.,Tsinghua University | Lu X.-Y.,Tsinghua University | Li L.,Guangdong Sanhe Pipe Pile Co.
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2010

The durability of Prestressed High-strength Concrete(PHC) pipe pile was affected by the corrosion resistance of their metal ends, which depended on the material of end plate(EP), apron(AP) and pretensioned PC steel bar(PC). Electrochemical corrosion behaviors of three kinds of EPs, such as cast steel, cold-bended steel, and Q235A steelin four typical simulated soil solutions including chloride salt soil, salina soil, neutral meadow soil and acid soil were investigated by natural immersion tests and electrochemical measurement techniques. The results showed that the corrosion rate of three kinds of EPs was smaller than that of PC and AP. The corrosion of PC and AP accelerated by cast steel EP was smaller than that by cold-bended steel and Q235A steel. The corrosion resistance of cast steel EP was poor. There was contact galvanic corrosion between EP and AP, EP and PC in simulated soil solutions. In couple of EP/AP, AP was anode. Cast steel EP was anode when the galvanic couple of cast steel EP/PC was in saline soil. In galvanic couples of cold-bended steel EP/PC and Q235A steel EP/PC, PC was anode. Contact corrosion quickens the damage of thin-walled AP and small-area PC, leading the premature failure of prestress. The corrosion of the existing metal ends in practical engineering should be improved.


Lin B.-L.,Tsinghua University | Lu X.-Y.,Tsinghua University | Li L.,Guangdong Sanhe Pipe Pile Co.
Cailiao Kexue yu Gongyi/Material Science and Technology | Year: 2010

Three kinds of single layer coatings of Zn, Zn15Al, 316L stainless steel and two kinds of double layer coatings with inner layer of Zn or Zn15Al and outer layer of 316L by arc spraying were developed to protect the metal ends of prestressed high-strength concrete (PHC) pipe piles against acid soil corrosion in south China. The corrosion behaviors of the coated Q235 steel samples in simulated Yingtan acid soil solution were investigated by natural immersion, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. The results show that the corrosion of the matrix Q235 steel is effectively inhibited by Zn, Zn15Al, Zn-316L and Zn15Al-316L coatings. The corrosion products on Zn and Zn15Al coated samples are compact and firm. The corrosion resistance indexes of both Zn and Zn15Al coated samples are improved significantly with corrosion time, and those of the latter are a little superior to those of the former. But the corrosion resistance of 316L coated samples is decreased quickly with immersion time.

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