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| EFFECT OF HIGH HYDROSTATIC PRESSURE ON DIFFUSING BEHAVIOR OF WATER THROUGH EPOXY COATING |
| LIU Ying, LIU Li, LI Ying, WANG Fuhui |
| State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 |
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Abstract The diffusing behavior of water through epoxy coating under ordinary pressure (1 atm) and high hydrostatic pressures in deep ocean (35 atm) was investigated by traditional gravimetric method and electrochemical impedance spectroscopy (EIS). The corresponding diffusion coefficients were calculated and the effect of hydrostatic pressures on kinetics of water adsorption was also analyzed. The results showed that high hydrostatic pressure accelerated the diffusion process of water through organic coating, and the diffusion mechanism had been changed from ideal Fick diffusion under 1atm to S type adsorption non-ideal Fick diffusion under 35 atm. The parameters for diffusion kinetics, including diffusion velocity, saturation time and saturated percent of water adsorption were significantly different under two environments. The changes of parameters relevant to the barrier property of epoxy coating with immersion time were also severer under high pressure, including the coating capacitance Cc, coating resistance Rc, and break-point frequency fb, resulting in coating failure before its lifetime.
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Received: 19 April 2011
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Corresponding Authors:
LI Ying
E-mail: liying@imr.ac.cn
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