TY - JOUR

T1 - The novel paste electrolyte measuring cell for EIS testing of the commonly used surface protection on bronze

AU - Soljic, Ines

AU - Soic, Ivana

AU - Eskinja, Magdalena

AU - Mujezinovic, Adnan

AU - Martinez, Sanja

N1 - Publisher Copyright: © 2023 Elsevier B.V.

PY - 2023/4

Y1 - 2023/4

N2 - The cell was tested on polished and patinated bronzes of different compositions, on sulfide 14 patina/Paraloid B-72-coated bronzes with different numbers of coating layers, on protected 15 bronze samples with different degrees of damage to the protective layers, and on uncoated and 16 coated patinated bronzes after 24 h conditioning in the condensation chamber. A quantitative 17 criterion of Phase Angle at 0.1Hz was deduced and explained. The systems show two or three 18 time constants, depending on the number and integrity of the layers. Capacitances of the highfrequency response that are attributed to the coating range from 1.8 to 31 nF/cm2 19 and capacitances of the medium-frequency response attributed to the patina range from 1.1 F/cm2 20 to 2.3 nF/cm2 21 , indicating Paraloid B-72 penetration into the pores of the patina. Log ∣Z∣ at 22 0.1Hz decreases with mechanical damage to the protective layers. Damage also leads to the 23 occurrence of the low-frequency response attributed to the Faradaic process on the substrate. 24 The three layers of Paraloid B-72 on the sulfide patina had Log ∣Z∣ at 0.1Hz around 8 and were 25 insensitive to the 24-hour condensation, indicating good protection. The cell was further 26 applied to different sides of bronze coins, so no electrical contact with the substrate was 27 required. The Kramers-Kronig test was applied to confirm the validity of the EIS results.

AB - The cell was tested on polished and patinated bronzes of different compositions, on sulfide 14 patina/Paraloid B-72-coated bronzes with different numbers of coating layers, on protected 15 bronze samples with different degrees of damage to the protective layers, and on uncoated and 16 coated patinated bronzes after 24 h conditioning in the condensation chamber. A quantitative 17 criterion of Phase Angle at 0.1Hz was deduced and explained. The systems show two or three 18 time constants, depending on the number and integrity of the layers. Capacitances of the highfrequency response that are attributed to the coating range from 1.8 to 31 nF/cm2 19 and capacitances of the medium-frequency response attributed to the patina range from 1.1 F/cm2 20 to 2.3 nF/cm2 21 , indicating Paraloid B-72 penetration into the pores of the patina. Log ∣Z∣ at 22 0.1Hz decreases with mechanical damage to the protective layers. Damage also leads to the 23 occurrence of the low-frequency response attributed to the Faradaic process on the substrate. 24 The three layers of Paraloid B-72 on the sulfide patina had Log ∣Z∣ at 0.1Hz around 8 and were 25 insensitive to the 24-hour condensation, indicating good protection. The cell was further 26 applied to different sides of bronze coins, so no electrical contact with the substrate was 27 required. The Kramers-Kronig test was applied to confirm the validity of the EIS results.

KW - Paraloid B-72

KW - bronze

KW - coins

KW - EIS

KW - paste electrolyte

UR - http://www.scopus.com/inward/record.url?scp=85147552269&partnerID=8YFLogxK

U2 - 10.1016/j.porgcoat.2023.107442

DO - 10.1016/j.porgcoat.2023.107442

M3 - Article

VL - 177

JO - Progress in organic coatings

JF - Progress in organic coatings

SN - 0300-9440

M1 - 107442

ER -