Identify defect levels in organic coatings

Recently, researchers have successfully determined defect levels in organic coatings, where electrochemical noise (EN) is measured in single-cell (SC) mode.
, field corrosion detection methods will be developed to identify defect levels in organic coatings.
new work aims to develop field corrosion detection methods to identify defect levels in organic coatings
C) by using electrochemical noise (EN) measured in Singe Cell (SC)
. Electrochemical sensors are used for defect identification, and the results show that the magnitude of electrochemical current noise (ECN) increases as defect levels rise.
successful differentiation of protection levels
Further data analysis based on power spectral density (PSD) and discrete wavelength analysis confirms that white noise levels WL and wave wave energy distributions can successfully distinguish between the protection levels of organic coatings.
the study was published today: Progress in Organics Volume 126, January 2019, Pages 53-61.
the
used in the marine environment is coated with
organic coating,
to prevent metal corrosion, thereby threatening the life of the material. Detecting corrosion damage to coated metals in the marine environment can assess the remaining service life of metals and clarify corrosion agents.
corrosion under an organic coating is an electrochemical process ,
1
,
2
, so
electrochemical impedance spectrum
(EIS) (
3
), polarization technology, electrochemical noise (EN) (
4
), and some local electrochemical techniques are the most commonly detected metal corrosion. Each method has its own unique advantages/disadvantages: polarization technology is not suitable for field corrosion detection because it causes large polarization of the system, which can lead to changes in the
corrosion potential
environment. Local electrochemical techniques


reviewed in the 5-minute study. Local EIS (
6
,
7
),
Scanning Electrochemical Microscope
(SECM), Scan Comparing Electrode Technology (SVET) (SVET) (
8
),
Scan Gavin Probe
(SKP) (
9
) and Scan
Ion Selection Electrode
Technology (SIET) have been successfully used to analyze the agents in corrosion-degrading organic coated metal systems, but these techniques are not easy to use to detect corrosion of field metals.
field studies, in-place detection of corrosion degradation is preferred because it does not interfere with the system to a large extent. Electrochemical noise (EN) is used to measure free corrosion levels in-place. The simplicity of EN measuring equipment makes EN an ideal technology for rapid corrosion detection. EN has been used to detect corrosion of
coating
,
,
,

,
corrosion resistance
can be quantified by the standard deviation of electrochemical position noise (EPN), the standard deviation of electrochemical current noise (ECN), the noise resistance
R
n

,
,
,
,
spectral noise resistance (

13
), power spectral density (PSD) (
4
,
16
,
1 7
analysis from small wave , in part signal standard deviation (SDPS) figures
18
) and
confusion
and in
19
. Meng et al. (
20
) uses EN to study the corrosion resistance of epoxy-coated metals under static pressure in alternating fluids in the ocean and concludes that EPN spikes in the coating are due to residual effects of pressure changes. Valentini, etc. The
parameters
by measuring EN were found to be very consistent with 21 resistance parameters obtained through EIS. Mojica, etc. The


polyurethane
film was evaluated with EN and the slope of the linear area in PSD was found to be an indicator of corrosion.
en settings for field testing are very important, and a simple, long-term and reliable setup is the ultimate goal. The traditional EN settings for painted metals are performed using a zero resistance current meter (ZRA) and consist of two nominally identical working electrodes and a reference electrode. Since it is difficult to test in the field, Jamali, Mills and the people (up to
4
,
14
,
s23 s
,
s 24 s
,
s 25 s
,
s26 s
,
s 27 s
,

,
, 29 ,
,
, 30 ,
,
, 31 ,
, single substrate ( SS ) , multiple single substrates ( MSS ) , basically no connection to substrates ( BNCS ) , and multiple substrate-free connections ( MNCS ) modes for laboratory and field applications . However, there are still disadvantages to using SS and BNCS because the resulting
R
n
comes from two SS or three BNCS regions, so
R
n
in each region is not easy to determine. Recently, Mills et al. A
(SC
mode has been developed for field corrosion testing. The SC mode consists of a working electrode (WE) and a reference electrode (RE), which is also used as a pair of electrodes (CE), assuming that the current flowing through the RE is small and does not affect the
stability of
the RE. The SC mode first measures the open-circuit level (OCP) and then the ECN (set a constant power level at the OCP) under constant-current control. Because SC mode is relatively easy to set up, it is convenient in field corrosion testing. However, when the coating deteriorates seriously, the current flowing through RE may increase significantly; In this case, it is not appropriate to use a single RE and requires another pair of electrodes (CE). Three-electrode systems (using separate CE and RE) are necessary for SC mode because the voltage of the "battery" including RE and WE is required before current noise can be measured. Therefore, in terms of complexity, individual cells are equally complex, with positive scoring intended to reduce ambiguity. But the MSS and MNCS models still have a long way to go
the
.
here, we use improved SC settings and mathematical methods such as power spectral density (PSD), statistical analysis and wavetle analysis to identify defect levels in organic coatings to extract useful parameters from EN data.