Ingress of water into organic coatings: Real-time monitoring of the capacitance and increase in mass

Determination of water uptake in organic coatings deposited on 2024 aluminium alloy: Comparison between impedance measurements and gravimetry

“…The mass fraction of water (ϕ m ) absorbed by the coating for each exposure time was calculated as exposed to pure water [18,19], although, even in this case, the resistivity of the electrolyte within the coating can be affected by ionic species initially present in the coating that become dissolved in water. Since our previous work [1][2][3][4][5] focused on assessing resistivity profiles, we did not discuss water uptake, and actually used the "water volume fraction" only as a formal intermediate parameter in calculations, without a direct physical meaning.…”

“…The determination of coating dielectric constant, the calculation of water uptake therefrom, and the comparison with direct gravimetric measurements have been the object of many studies. Reports in the literature include studies in which both EIS and gravimetric measurements were made on metal-supported coatings [12,[16][17][18][19][20][21][22], where both were made on free-standing films [12,[23][24][25][26], and where impedance was measured with supported coatings and mass variation with free films [27][28][29]. Different authors have put forward reasons for preferring free films or supported coatings.…”

On the role of water, temperature, and glass transition in the corrosion protection behavior of epoxy coatings for underground pipelines

“…It should be noted that two or more diffusion processes were reported in other coating systems. 46,47 The time for the coatings to reach 50% saturation was determined from this plot. Using equation (2), the water diffusivities in the bisphenol A coating and the Novolac coating at 20°C were determined to be 2.7 9 10 À10 and 4.1 9 10 À10 cm 2 /s, respectively.…”

Reduced indentation recovery temperature at the surface of a crosslinked epoxy coating in humid conditions

“…The exposure to 95% RH produces much greater recovery than at the lower RH. Although it is not a focus here, the increased water content of the films may be in more than one form 13 and so affects the mechanical response differently. Figure 4 shows the indentation recovery at different temperatures with a set RH.…”