The rate of drying of moisture from a metal surface and its implication for time of wetness

Cole, Ivan; Holgate, R.; Kao, Pon; Ganther, W. D.

doi:10.1016/0010-938x(94)00146-w

Cited by 26 publications

(11 citation statements)

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“…Some work exists, such as a study by Cole et al 7 which define drying rates in controlled conditions in the laboratory.…”

Section: Introductionmentioning

confidence: 99%

Experimental determination of time taken for openly exposed metal surfaces to dry

Cole¹,

Ganther²

2006

Corrosion Engineering, Science and Technology

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The time taken for wetness sensors on zinc plates, openly exposed to the atmosphere, to dry was analysed at four sites in southern Australia. The sites cover a range of environmental conditions from inland to marine. A number of typical drying patterns were observed, and it was found that these patterns could be related to the environmental severity and the probable presence of various salt contaminants. Therefore, at the marine site drying was frequently slow (.4 h) and appeared to be controlled by the presence of salts with a low deliquescent relative humidity (DRH) such as MgCl 2 . In contrast, at the inland sites drying was generally more rapid, which was consistent with either the drying of a clean surface or that of a surface controlled with salts of high DRH such as NaCl. The present paper presents histograms of drying rate for each site and the relationship between the distributions in drying rate and the environmental conditions is discussed. The relevance of the present study to modelling of atmospheric corrosion and to the design of cyclic tests to duplicate atmospheric corrosion is also discussed.

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“…Some work exists, such as a study by Cole et al 7 which define drying rates in controlled conditions in the laboratory.…”

Section: Introductionmentioning

confidence: 99%

Experimental determination of time taken for openly exposed metal surfaces to dry

Cole¹,

Ganther²

2006

Corrosion Engineering, Science and Technology

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“…[18][19][20] One process that has attracted significant attention is the role of wetting and drying in controlling surface oxide development and corrosion rate on metal surfaces. Cole 20 developed a masstransport model to determine drying rates.…”

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confidence: 99%

A Study of the Wetting of Metal Surfaces in Order to Understand the Processes Controlling Atmospheric Corrosion

Cole

Ganther

Sinclair

et al. 2004

J. Electrochem. Soc.

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This paper explores the simple principle that a metal surface wets when the surface relative humidity ͑RH͒ exceeds the deliquescent RH ͑DRH͒ of any salts on the surface. Data from field exposures across 19 sites in China, the Philippines, Indonesia, and Australia is used to determine the conditions under which openly exposed surfaces wet. At each site, surface temperature ͑of a zinc plate͒, ambient RH, sensor wetness, airborne salinity, and gaseous SO x and NO x were determined over a one-year period. In conjunction with these microclimate measures, the chemistry of airborne and deposited aerosols, as well as rainwater, were measured. Complimentary data from an environmental scanning electron microscope are presented in which salts derived from the evaporation of sea salt are rewetted. Using all of this data, an assessment of the probable contaminants controlling sensor wetting at each site is made. It is found that sites with similar International Standard Organization, ͑ISO͒ 9223, classifications in terms of industrial and marine airborne pollutants show similar surface contaminants and wetting characteristics. It is proposed that dominant contaminates can be identified for each ISO classification that are consistent with the general principle that wetting occurs when surface RH exceeds the DRH of the salts making up the contaminates. These salts can change from day to day due to the continual change in the composition of the contaminates and the ongoing homogenization of previously deposited salts through chemical reaction between salts and with the surface. Rain events usually clean the surface and start the cycle over again. The application of these findings to process models of corrosion is discussed, while generalized rules for predicting surface wetting based on climate data are proposed. It is found that these generalized rules predict total time of wetness to a high degree of accuracy.The concept of time of wetness ͑TOW͒ has been a very useful one for atmospheric corrosion scientists. 1 Indeed, the principle that corrosion can only occur in the presence of an electrolyte is based on fundamental electrochemical considerations. 2 Since the TOW concept was first proposed, sensors to measure TOW, 3-5 dose functions to define metallic corrosion 6-8 as a function of TOW, and degradation maps 9 based on these dose functions have been developed. However, the approximation commonly used to estimate TOW and included in International Standard Organization ͑ISO͒ 9225 ͓that TOW is the time when temperature is above 0°C and relative humidity ͑RH͒ is above 80%͔ cannot be directly derived from an understanding of the processes of surface wetting. Further studies of hygroscopic salts and aerosols indicate that salts, and thus the surfaces that they are on, may wet over a range of RH, depending on the deliquescent RH ͑DRH͒ of the salt. [10][11][12] In recent years, a number of authors have proposed refinements to the TOW concept in order to either derive better statistical fit with their corrosion data, or to account for...

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“…Though the practical open environment cannot be regarded as a closed system, at least for short periods of time, the surrounding region of the samples can be considered a closed system, where the heat flux and the flow of humid air remain stable and move freely around the samples [15,36]. Consequently, the heat flux around the exposed samples remains constant, which results in the occurrence of the constant dew point [36][37][38]. The constant dew point corrosion testing model therefore has a more concrete base than other simulation methodologies in terms of its ability to model the practical conditions.…”

Section: Corrosion Productsmentioning

confidence: 99%

Constant Dew Point Corrosion Tests for Metals

Dan¹,

Muto²,

Hara³

2014

Developments in Corrosion Protection

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The rate of drying of moisture from a metal surface and its implication for time of wetness

Cited by 26 publications

References 1 publication

Experimental determination of time taken for openly exposed metal surfaces to dry

Experimental determination of time taken for openly exposed metal surfaces to dry

A Study of the Wetting of Metal Surfaces in Order to Understand the Processes Controlling Atmospheric Corrosion

Constant Dew Point Corrosion Tests for Metals

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