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| CORRELATION BETWEEN CONTROL FACTORS AND TIME OF WETNESS OF Q235 STEEL UNDER Cl-, SO42- AND CO32- CONTAMINATED LIQUID LAYER |
| TANG Zilong1;2; LI Chao1; QU Wenchao1; SONG Xin1 |
1．School of Materials Science and Engineering; Tianjin University; Tianjin 300072
2．Tianjin Key Laboratory of Composite and Functional Materials; Tianjin University; Tianjin 300072 |
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Abstract Time of wetness (TOW) of Q235 steel covered by thin liquid layer of 1 mmol/L NaCl，10 mmol/L Na2SO4 and Na2CO3 is measured by taking consideration of three control factors, i.e. temperature (Temp), relative humility (RH) and time of immersion (TOI), as well as corrosion deposits. The standardization procedure from data mining is adopted and applied to all parameters before a linear model is introduced to correlate the TOW and its control factors. Effect and pattern of the control factors as well as corrosion deposits on TOW is studied. The result shows that the pattern of temperature and RH on TOW is greatly changed due to the involvement of Cl-, SO42- and CO32- ions compared with that without these contaminants. Depending on the chemical/physical properties of the contaminants and the composition and distribution of corrosion deposits, the contribution of temperature and RH terms to TOW could be reversed or enhanced or weakened. Specifically, the TOW behavior can be clustered into two sections with the threshold values of 24 ℃ and RH 70%~80% which is determined approximately and conclusively. In each section, the contribution of temperature and RH to TOW is changed at different levels. At the end, the synergic effect of temperature and relative humidity on TOW is found and discussed in detail including the cause of this effect and possible dependence on the contaminating ions and corrosion deposits.
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Received: 29 October 2008
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Corresponding Authors:
TANG Zilong
E-mail: zlt633@gmail.com
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