Which better In the experimental work for corrosion inhibition of metallic alloys, the calculation for determining the inhibition efficiency (E%) by the equation from corrosion rate (CR) by the electrochemical test or calculate the E% from weight loss technique?
Dear Ali Sabea,
you can refer to this:
https://corrosion-doctors.org/Inhibitors/Efficiency.htm
Kind regards
Gedvidas Bikulcius
Electrochemical tests (e.g. polarization curves) are usually more sensitive and give you additional information about the inhibition mechanisms (anodic/cathodic/mixed). Nevertheless, standard immersion tests (with determining weight loss of coupons) are often requested in industry to prove the effectiveness of the inhibitor.
Dear Ali Sabea Hammood
Two cases should considered :
Case1: studying simple corrosion system where obtained values of corrosion potential and corrosion current density by electrochemical polarization, are in agreement with the weight loss method so you can consider both techniques (see ref1 as example).
Case2: studying complex corrosion system. This makes corrosion rate between electrochemical and weight-loss techniques to differ and the obtained values with weight loss are more certain and reproducible (see ref2 as example).
Best regards
ref1- https://www.mdpi.com/2076-3417/9/21/4684/htm
ref2- https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0200595&type=printable
Electrochemical tests provide you with information on the instantaneous corrosion rate and can be used to calculate performance.
Gravimetric tests allow obtaining average corrosion rate during all measurement time.
regards
S Krakowiak
Hi,
Electrochemical tests show you real-time kinetics of the cathodic and anodic processes. In this regard, polarization tests are not very useful for a long-time performance evaluation. Then, EIS can be used for the evaluation.
Indeed, weight loss tests are suitable for a long-period average corrosion rate monitoring. However, your should remember that in the case of severe local corrosion these results may be somehow misleading
What is percentage of inhibition efficiency?how do you calculate absence and presence of inhibitors in tafel graph
Dear Dr. Ali Sabea Hammood,
the following equation determined the inhibition efficiency (I.E.) and surface coverage (θ) by weight loss measurements, where W1 and W0 are the weight loss values in the presence and absence of inhibitor (First image)
The inhibition efficiency (IE) and corrosion rate (CR) were calculated by Electrochemical measurements by using the formulae (Second Image), where i’corr and icorr are the corrosion current density of the substrate in the presence and absence of inhibitor. M = Atomic mass of metal, ρ = density of corroding metal, Z = Number of electrons transferred per metal atom.
For more details, please see the source:
- Synthesis, characterization and corrosion inhibition efficiency of N-(4-(Morpholinomethyl Carbamoyl Phenyl) Furan-2-Carboxamide for brass in HCl medium
N. Zulfareen, K. Kannan, T. Venugopal, S.Gnanavel
Arabian Journal of Chemistry, Vol. 9, Issue 1, Pages 121-135 (2016)
Available at: https://www.sciencedirect.com/science/article/pii/S1878535215002634
In addition to the presence of the inhibitor, its surface morphology and its distribution are of extreme importance. These characteristics are strongly linked to its protective power towards the substrate and a detailed surface analysis can often provide interesting information.
My best regards, Pierluigi Traverso.
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