Electrochemical Evaluation of Corrosion Inhibitors and
Protective Coatings used on Bronze Artifacts
Mahrouse, Ya, Ismail, Bb, Rifai, Mc
a
conservation department, faculty Archaeology, South valley university.
Yussri_25@yahoo.com
b
conservation department, faculty Archaeology, South valley university.
c
conservation department, faculty Archaeology, Cairo university.
Kay words: corrosion, inhibitors, bronze
Abstract
The main objective of this study was to evaluate the
performance of some common corrosion inhibitors and
protective coatings used in conservation of bronze artifacts by
electrochemical measurements and weight loss. The corrosion
inhibitors used in this work were Benzotriazole (BTA)
(C6H5N3), 2-mercaptobenzothiazole (MBT), while the protective
Coatings used were Paraloid B72 and Paraloid B66.
The electrochemical test was carried out using apparatus
[potential potentiostas Galvanic ( model 273 A) EG and G] with
this conditions: initial potential = 0.1, final potential = 0.1 V,
Sample area = 2 CM2 , Scan rate = 5 MVS-1, The capacity of
Solution = 50 ml ( mix. /HCl), with three-electrode cell. A
platinum was used as counter. electrode, Silver Silver chloride
[Ag/AgCl] as eference electrode , and bronze coupons as a
working electrode and all experiments were performed at room
temperature.
Electrochemical measurements were carried out in the following
corrosive mediums (0,2 g/L-1 Na2SO4 + 0.2 g/L-1 NaHCO3+ 0,2
g/L-1 NaCl ) acidified to pH 5 by addition of dilute HCl and
(0.5M HCl ) on binary copper alloy (bronze) coupons with the
composition Cu 93 Sn 6 that it determined by EDXRF.
In both corrosive mediums, electrochemical techniques showed
that Benzotriazole and 2-mercaptobenzothiazole were efficient
as corrosion inhibitors for bronze and Paraloid B-66 showed
better results than Paraloid- B72. The corrosion inhibitor
effectiveness of the selected compounds was rated BTA > MBT
for the inhibitors and B 66 > B 72 for the protective coatings.
Weight loss tests were performed on the coupons using Cupric
chloride The corrosion inhibitor effectiveness of the selected
compounds after two and four weeks was rated BTA > MBT
and B- 66 > B- 72.
the apparatus used in the measurement
of the electrochemical corrosion inhibitors
form of coupons
-2
-3
6
-4
3
1
-5
5
-2
Log i, mA.Cm
4
2
-6
-7
-8
-9
-300
-250
-200
-150
-100
-50
0
E, mV(Ag/AgCl)
polarization curves of treated and Untreated coupons
with corrosion inhibitors in: (0.5M HCl,
PM of treated coupon by BTA
in The first medium
SEM of treated coupon by BTA
in tow mediums
SEM of treated coupon by Paraloid
B- 72 in tow mediums
PM of treated coupon by BTA in The second medium