Evaluation of coating resistivity for pigmented/unpigmented epoxy coatings under marine alternating hydrostatic pressure

doi:10.1016/j.jmst.2019.09.011

Abstract

Abstract:

To realize a rapid evaluation of coating degradation under alternating hydrostatic pressure (AHP), appropriate physical models of electrochemical impedance spectroscopy (EIS) data fitting were respectively developed for epoxy coatings with and without pigments, based on their different water absorption behaviours. Power-law model was selected to evaluate the anti-permeability of epoxy varnish (EV) coating, which tends to form through pores in the coating structure. On the other hand, two-layer model based on Young theory was developed to evaluate the anti-permeability of pigmented epoxy coating. Consequently, the resistivity profile with coating thickness was calculated as a critical parameter to describe the anti-permeability of coating at different immersion time. The interpretation of water diffusion dynamics based on different coating structures was also given, which is responsible for the choice of distribution models.

Key words: Organic coatings, Coating resistivity, Distribution models, EIS, Alternating hydrostatic pressure

Fandi Meng, Li Liu, Yu Cui, Fuhui Wang. Evaluation of coating resistivity for pigmented/unpigmented epoxy coatings under marine alternating hydrostatic pressure[J]. J. Mater. Sci. Technol., 2021, 64: 165-175.

Figures/Tables 20

Fig. 1. Schematic diagrams of Young model of a film with an exponential decline of conductivity perpendicular to the surface (a) and Power-law model present as liner relation between resistivity of layer and thickness in log-log coordinate (b).

Fig. 2. SEM micrograph of cross-section for EM coating.

Fig. 3. Nyquist plots of EV coating at different immersion time: (a) 0-24 h, (b) 25-82 h, (c) 83-120 h, and (d) plot of |Z| vs. frequency.

Fig. 4. Nyquist plots of EM coating at different time: (a) 0-40 h, (b) 41-95 h, (c) 96-150 h and (d).151-240 h.

Fig. 5. Optical images after immersion of (a) EV coating for 120 h and (b) EM coating for 240 h.

Fig. 6. Water absorption curves for EV and EM coatings under AHP.

Fig. 7. Stylized picture of Fickian diffusion for EV coating and two-stage absorption for EM coating under AHP. The relative water uptake is plotted as a square function of time.

Fig. 8. Phase angle curves as a function of frequency for dry EV and EM coatings (scatters: the experimental data; solid line: the fitting results by power-law model).

Table 1 Best-fitted values of adjustable parameters obtained by regressing the power-law model to experimental data for dry varnish coating.

α	ρ₀ /Ω cm	ρ_d /Ω cm	ε_c
0.934	3.90 × 10¹³	1.85 × 10⁷	8.57

Fig. 9. Resistivity as a function of coating thickness for dry EV and EM coatings.

Fig. 10. Phase angle plot of EV coating under different immersion time (scatters: the experimental data; solid line: the regression results by power-law model).

Table 2 Best-fitted values of adjustable parameters for EV coating under different time.

Time/h	α	ρ₀ /Ω cm	ε_c
5	0.928	3.90 × 10¹³	8.58
24	0.921	3.90 × 10¹³	8.58
49	0.912	1.01 × 10¹³	8.59
98	0.896	1.09 × 10¹⁰	9.64

Fig. 11. Resistivity distribution as a function of different immersion time for varnish coating.

Fig. 12. (a) Phase angle as functions of frequency obtained for EM coating after immersion 41 h (The experimental data is compared with the regression results of two models); (b) phase angle plot fitted by Young model under different time.

Table 3 Values of parameters for EM coating by Young model under medium immersion time.

Time/h	δ	ρ₀ /Ω cm	ε_w
41	4.79 × 10^-4	8.99 × 10¹³	12.0
85	8.74 × 10^-4	1.64 × 10¹²	18.6
168	1.35 × 10^-3	1.12 × 10¹¹	19.8

Fig. 13. Schematic diagram of the two-layer model for EM coating.

Fig. 14. Experimental data and fitting results by the two-layer model.

Table 4 Values of parameters for EM coating by two-layer model under early immersion time.

Time/h	λ/cm	ρ₀ /Ω cm	ε_w
8	0.0041	1.57 × 10¹⁴	9.03
16	0.0011	1.57 × 10¹⁴	11.69
24	0.0009	1.57 × 10¹⁴	11.75
31	0.0003	1.57 × 10¹⁴	11.99
41	0.0001	1.16 × 10¹⁴	12.03

Fig. 15. Resistivity distribution as a function of different immersion time for EM coating.

Fig. 16. Schematic cross-section and water diffusion behaviour for EV and EM coatings under AHP.

References 41

[1]	G.K.V.D. Wel, O.C.G. Adan, Prog. Org. Coat., 37(1999), pp. 1-14.
[2]	D.H. Xia, J.Q. Wang, Z. Wu, Z.B. Qin, L.K. Xu, W.B. Hu, Y. Behnamian, J.L. Luo , Sens. Actuator B: Chem., 280(2019), pp. 235-242.
[3]	D.H. Xia, Y. Song, S.Z. Song, Y. Behnamian, L.K. Xu, Z. Wu, Z.B. Qin, Z.M. Gao, W.B. Hu , Prog. Org. Coat., 126(2019), pp. 53-61.
[4]	B. Liu, Z.G. Fang, H.B. Wang, T. Wang , Prog. Org. Coat., 76(2013), pp. 1814-1818.
[5]	Y. Liu, J.W. Wang, L. Liu, Y. Li, F.H. Wang , Corros. Sci., 74(2013), pp. 59-70.
[6]	J. Liu, X.B. Li, J. Wang, T.Y. Luo, X.M. Wang , Prog. Org. Coat., 76(2013), pp. 1075-1081.
[7]	W.L. Tian, L. Liu, F.D. Meng, Y. Liu, Y. Li, F.H. Wang , Corros. Sci., 86(2014), pp. 81-92.
[8]	F.D. Meng, L. Liu, W.L. Tian, H. Wu, Y. Li, T. Zhang, F.H. Wang , Corros. Sci., 101(2015), pp. 139-154.
[9]	W. Tian, F. Meng, L. Liu, Y. Li, F. Wang , Prog. Org. Coat., 82(2015), pp. 101-112.
[10]	R. Liu, L. Liu, F. Meng, W. Tian, Y. Liu, Y. Li, F. Wang , Prog. Org. Coat., 123(2018), pp. 168-175.
[11]	F. Meng, Y. Liu, L. Liu, Y. Li, F. Wang , Materials (Basel), 10(2017), p. 715.
[12]	F.D. Meng, L. Liu, Y. Li, F.H. Wang , Prog. Org. Coat., 105(2017), pp. 81-91.
[13]	A. Amirudin, D. Thierry , Prog. Org. Coat., 26(1995), pp. 1-28.
[14]	J.R. Scully, , J. Electrochem. Soc., 136(1989), pp. 979-990.
[15]	L. Beaunier, I. Epelboin, J.C. Lestrade, H. Takenouti , Surf. Technol., 4(1976), pp. 237-254.
[16]	M. Kendig, F. Mansfeld, S. Tsai , Corros. Sci., 23(1983), pp. 317-329.
[17]	D.H. Xia, C. Ma, S. Song, L. Xu, , J. Electrochem. Soc., 166(2019), pp. B1000-B1009.
[18]	B.R. Hinderliter, S.G. Croll, D.E. Tallman, Q. Su, G.P. Bierwagen , Electrochim. Acta, 51(2006), pp. 4505-4515.
[19]	N. Anh Son, M. Musiani, M.E. Orazem, N. Pebere, B. Tribollet, V. Vivier , Electrochim. Acta, 179(2015), pp. 452-459.
[20]	B. Hirschorn, M.E. Orazem, B. Tribollet, V. Vivier, I. Frateur, M. Musiani, , J. Electrochem. Soc., 157(2010), pp. C458-C463.
[21]	L. Young , Trans. Faraday Soc., 51(1955), pp. 1250-1260.
[22]	A.A. Roche, M. Aufray, J. Bouchet, J. Adhes ., 82(2006), p. 861.
[23]	S. Amand, M. Musiani, M.E. Orazem, N. Pébère, B. Tribollet, V. Vivier , Electrochim. Acta, 87(2013), pp. 693-700.
[24]	P. Cordoba-Torres , Electrochim. Acta, 225(2017), pp. 592-604.
[25]	P. Córdoba-Torres , Electrochim. Acta, 241(2017), pp. 535-543.
[26]	H. Göhr, J. Schaller, C.A. Schiller , Electrochim. Acta, 38(1993), pp. 1961-1964.
[27]	R.E. Delarue, C.W. Tobias, , J. Electrochem. Soc., 106(1959), pp. 827-833.
[28]	A. Clauset, C.R. Shalizi , M.E.J. Newman, SIAM Rev., 51(2009), pp. 661-703.
[29]	R. Hurt, J. Macdonald , Solid State Ionics, 20(1986), pp. 111-124.
[30]	B. Hirschorn, M.E. Orazem, B. Tribollet, V. Vivier, I. Frateur, M. Musiani, , J. Electrochem. Soc., 157(2010), pp. C452-C457.
[31]	ISO2808-2007, Classification, ISO Geneva , 2007.
[32]	W.L. Tian, F.D. Meng, L. Liu, Y. Li, F.H. Wang , Prog. Org. Coat., 82(2015), pp. 101-112.
[33]	D. Mackay, W.Y. Shiu, J. Phys. Chem Ref. Data, 10(1981), pp. 1175-1199.
[34]	M.D. Destreri, J. Vogelsang, L. Fedrizzi , Prog. Org. Coat., 37(1999), pp. 57-67.
[35]	F. Mansfeld, L.T. Han, C.C. Lee, G. Zhang , Electrochim. Acta, 43(1998), pp. 2933-2945.
[36]	S. Skale, V. Dolecek, M. Slemnik , Corros. Sci., 49(2007), pp. 1045-1055.
[37]	J.T. Zhang, J.M. Hu, J.Q. Zhang, C.N. Cao , Prog. Org. Coat., 49(2004), pp. 293-301.
[38]	F. Bellucci, L. Nicodemo , Corrosion, 49(1993), pp. 235-247.
[39]	Y.M. Chen, A.S. Nguyen, M.E. Orazem, B. Tribollet, N. Pebere, M. Musiani, V. Vivier , Electrochim. Acta, 219(2016), pp. 312-320.
[40]	A.S. Nguyen, M. Musiani, M.E. Orazem, N. Pebere, B. Tribollet, V. Vivier , Corros. Sci., 109(2016), pp. 174-181.
[41]	A.S. Nguyen, N. Causse, M. Musiani, M.E. Orazem, N. Pebere, B. Tribollet, V. Vivier , Prog. Org. Coat., 112(2017), pp. 93-100.