Electrochemical Study of Calcareous Deposit Formation in Simulated Soil Solution under Cathodic Protection

2019 ◽  
Vol 821 ◽  
pp. 307-312
Author(s):  
Phumlani Mjwana ◽  
Philippe Refait ◽  
Babatunde A. Obadele ◽  
Marc Jeannin ◽  
Peter Olubambi
Keyword(s):  
Cathodic Protection ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Diffusion Reaction ◽  
Steady Increase ◽  
Applied Potential ◽  
Non Invasive ◽  
Surface Time ◽  
Bode Plots

Cathodic protection induces the formation of a calcareous layer has been shown to improve metal protection against corrosion by reducing the oxygen diffusion on the metal surface. The present study focuses on the electrochemical scaling induced by the application of cathodic polarisation. A combination of non-invasive in-situ electrochemical techniques and electrochemical impedance spectroscopy was used. Metal/electrolyte interface behaviour was studied using voltammetry to determine the controlling anodic and cathodic reactions. One-week long experiments were conducted. Applied potential –1.2 VSCE was shown to enable the formation of CaCO3 allotropes calcite and aragonite, and brucite due to increased interfacial pH which resulted in the formation of hydrogen at the electrode surface. Time constants from bode plots for applied potential –1.2 VSCE also illustrated the inhomogeneity of the calcareous layer. Modelling of polarisation curves illustrated a “passivation” phenomenon which resulted from formation of hydroxyl cations. This was further validated by bode plots with the added information on the diffusion reaction process. High frequency behaviour showed a steady increase in the electrolyte resistance which may be attributed to the formation of the calcareous layer. Evidence of the initial Mg-gel porous layer, which precedes the formation of brucite, was found.

scholarly journals Corrosion Performance of AISI-309 Exposed to Molten Salts V2O5-Na2SO4at 700°C Applying EIS andRpElectrochemical Techniques

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
E. F. Diaz ◽  
C. Cuevas-Arteaga ◽  
N. Flores-García ◽  
S. Mejía Sintillo ◽  
O. Sotelo-Mazón
Keyword(s):  
Molten Salts ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Metallic Surface ◽  
Corrosion Performance ◽  
Potentiodynamic Polarization Curve ◽  
Linear Polarization Resistance ◽  
Second Stage ◽  
Tafel Slopes ◽  
Bode Plots

The corrosion performance of AISI-309 exposed 5 days to molten salts 50 mol% V2O5-50 mol% Na2SO4at 700°C is reported in this paper. Such evaluation was made using three electrochemical techniques: potentiodynamic polarization curve (PC), electrochemical impedance spectroscopy (EIS), and linear polarization resistance (Rp). FromPC, the Tafel slopes,Icorr, andEcorrwere obtained. From Nyquist and Bode plots, it was possible to determine two different stages; the first one showed just one loop, which indicated the initial formation of Cr2O3layer over the metallic surface; after that, the dissolution of Cr2O3formed a porous layer, which became part of the corrosion products; at the same time a NiO layer combined with sulfur was forming, which was suggested as the second stage, represented by two capacitive loops. EIS plots were in agreement with the physical characterization made from SEM and EDS analyses. Fitting of EIS experimental data allowed us to propose two electrical circuits, being in concordance with the corrosion stages. Parameters obtained from the simulation of EIS data are also reported. From the results, it was stated that AISI-309 suffered intergranular corrosion due to the presence of sulfur, which diffused to the metallic surface through a porous Cr2O3layer.

In-Situ Characterization Of Ultra-Small Magnetic Junctions Made By Electrochemical Techniques

2001 ◽  
Vol 674 ◽  
Author(s):  
A. Sokolov ◽  
J.R. Jennings ◽  
C-S Yang ◽  
J. Redepenning ◽  
B. Doudin
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Low Temperatures ◽  
Coulomb Blockade ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
In Situ Characterization

ABSTRACTElectrochemical impedance spectroscopy is used to characterize the growth of NiO over Ni electrodes. We find a limited increase of thickness and a significant increase of porosity of the oxide as a function of time and anodization potential. Conductance measurements performed on Ni/NiO/Co junctions of 30 nm diameters indicate the presence of a Coulomb blockade at low temperatures and small bias. Tunneling is observed at higher bias. Small magnetoresistance ratios (1%) are found.

Properties of Oxide Formed on Aluminium in Aqueous Acetate Buffer

2006 ◽  
Vol 519-521 ◽  
pp. 717-722 ◽  
Author(s):  
N. Giskeødegård ◽  
O. Blajiev ◽  
A. Hubin ◽  
H. Terryn ◽  
Ola Hunderi ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Potential Temperature ◽  
Ex Situ ◽  
Pure Aluminium ◽  
Film Properties ◽  
Hydrated Layer ◽  
Transmission Electron ◽  
Controlled Potential

The properties of oxide formed on pure aluminium in acetate buffers under controlled potential, temperature, and pH are characterized by in situ electrochemical techniques and spectroscopic visual ellipsometry (VISSE). Monitoring the current density (cd) during transition between different applied potentials gives direct information about Faradaic changes in the oxide properties, while the ellipsometer monitors the changes in the actual thickness and refractive index of the film. Electrochemical impedance spectroscopy (EIS) reveals, in addition to film properties, information about the charge transfer processes and adsorption at steady-state conditions. VISSE and ex situ transmission electron microscopy (TEM) indicate the presence of a two layered oxide structure, consisting of the barrier and a porous hydrated layer. The thickness and density of these two layers are monitored in situ during growth and dissolution. The thickness of the barrier layer depends reversibly on the applied potential, while the thickness of the hydrated layer is less affected by the potential. The absorption sensitive parameter is correlated with the buffer concentration and therefore believed to be related to the acetate.

scholarly journals In-situ multi-analytical study of ongoing corrosion processes on bronze artworks exposed outdoor

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 241
Author(s):  
Leila Es Sebar ◽  
Leonardo Iannucci ◽  
Caterina Gori ◽  
Alessandro Re ◽  
Marco Parvis ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Three Dimensional ◽  
Corrosion Products ◽  
Invasive Approach ◽  
Non Invasive ◽  
Combined Use ◽  
Art Collection ◽  
The Stability ◽  
Microclimate Conditions

<p class="Abstract">This paper presents a long-term in-situ campaign to monitor contemporary bronze statuary exposed outdoors. The case study relates to the characterisation of three sculptures belonging to the Gori Art Collection, located in the Fattoria di Celle: ‘Cavaliere’ and ‘Miracolo – Composizione’ by Marino Marini and ‘Due forme o due ombre n°2’ by Luciano Minguzzi. The overall conservation state of the sculptures was investigated by means of a multi-analytical and non-invasive approach, involving different techniques. Three-dimensional photogrammetry was performed to fully document the artworks. The chemical and microstructural features of the corrosion patinas were then characterised through X-ray fluorescence and Raman spectroscopy. In addition, the stability and the protective effectiveness of the corrosion products were assessed by electrochemical impedance spectroscopy. Thanks to the combined use of these specific techniques, the information extracted through the different analyses could be correlated with each other and with the exposure conditions. The different corrosion products were identified as being primarily copper sulphates and phosphates, and they were correlated with the different microclimate conditions related to their location on the statues. The information gathered from the presented multi-analytical approach represents the fundamental knowledge required to develop a tailored conservation project to assure the long-lasting preservation of these artworks.</p>

scholarly journals Smart Electrochemical Portable Tools for Cultural Heritage Analysis: A Review

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4303 ◽  
Author(s):  
Valentini
Keyword(s):  
Cultural Heritage ◽  
Electrochemical Sensors ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Organic Layer ◽  
Scientific Impact ◽  
Organic Layers ◽  
Electrochemical Devices ◽  
Metallic Corrosion

. Protecting Cultural Heritage (CH) from corrosion and other environmental damages, mainly involving metallic or organic layers contained in artwork, represents a major challenge for conservation scientists. Electrochemical techniques provide useful information about the deterioration effects of metallic coatings and organic layers. Recently, Electrochemical Impedance Spectroscopy (EIS) has been successfully applied in the study of metallic corrosion. However, EIS has not succeeded in becoming a routine technique, due to problems regarding both instrumental apparatus (which is not ideal for in situ analysis, especially with previous cell configurations), and the difficulty with data processing. At the same time, new portable electrochemical sensors, immunosensors, and biosensors have successfully made a scientific impact, mainly with in situ diagnosis of organic components contained in CH objects. For this purpose, this review presents two sections: the first describes the analytical optimization of impedance electrochemical cell geometries that are suitable for in situ metal-coating investigation; the second reports on the assembly of small electrochemical sensors, immunosensors, and biosensors, which useful for in situ organic layer characterization. This overview summarizes the state of the art regarding the application of electrochemical techniques and small electrochemical devices as alternative tools for the understanding of CH.

Efficiency of diagnosis and treatment non-invasive and microinvasive sgamous cell cervical cancer

2020 ◽  
pp. 71-74
Author(s):  
M.M. Melnyk ◽  
◽  
S.V. Nespradko ◽  
I.V. Goncharuk ◽  
M.V. Marchenko ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Key Words ◽  
National Cancer Institute ◽  
Reproductive Function ◽  
Diagnosis And Treatment ◽  
Non Invasive ◽  
Corpus Uteri ◽  
Complex Program ◽  
Early Cervical Cancer

The objective: analyse the effectiveness of diagnosis and treatment for early cervical cancer. Materials and methods. Analysed 107 cases of women’s disease on CIN ІІІ, cancer in situ, they were on treatment in National cancer institute and Kyiv dictrict cancer dispensary from 2010 till 2015 years. Results. Diagnosed percent relapse CIN ІІІ, cancer in situ contain 4.57% uninvasive and invasive form – 0.94%. Conclusion. According diagnostic CIN ІІ and CIN ІІІ is recommended to do treatment conization and dynamic dispensary observation. Are making complex program of infection HPV16, 18. In appering of margins resection some elements of tumor after wider conization by forms of cancer in situ. Many of expansive burns in cervical glands, in making of reproductive function, going disease (nodel leiomyoma of corpus uteri etc). In perspective is accept the notion of looking after and screening research of considering infection HPV16, 18 on CIN І, CIN ІІ. Key words: cervical cancer, сancer in situ, CIN І–ІІІ, diagnostic, treatment, conization.

The study of the electrochemical properties of zinc-rich coating on the base of water sodium silicate

2019 ◽  
Vol 24 (4) ◽  
pp. 51-58
Author(s):  
Le Hong Quan ◽  
Nguyen Van Chi ◽  
Mai Van Minh ◽  
Nong Quoc Quang ◽  
Dong Van Kien
Keyword(s):  
Carbon Steel ◽  
Electrochemical Properties ◽  
Sodium Silicate ◽  
Cathodic Protection ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Electrical Contact ◽  
Electrochemical Impedance Spectra ◽  
Pure Zinc ◽  
Electric Circuits

The study examines the electrochemical properties of a coating based on water sodium silicate and pure zinc dust (ZSC, working title - TTL-VN) using the Electrochemical Impedance Spectra (EIS) with AutoLAB PGSTAT204N. The system consists of three electrodes: Ag/AgCl (SCE) reference electrode in 3 M solution of KCl, auxiliary electrode Pt (8x8 mm) and working electrodes (carbon steel with surface treatment up to Sa 2.5) for determination of corrosion potential (Ecorr) and calculation of equivalent electric circuits used for explanation of impedance measurement results. It was shown that electrochemical method is effective for study of corrosion characteristics of ZSC on steel. We proposed an interpretation of the deterioration over time of the ability of zinc particles in paint to provide cathodic protection for carbon steel. The results show that the value of Ecorr is between -0,9 and -1,1 V / SCE for ten days of diving. This means that there is an electrical contact between the zinc particles, which provides good cathodic protection for the steel substrate and most of the zinc particles were involved in the osmosis process. The good characteristics of the TTL-VN coating during immersion in a 3,5% NaCl solution can also be explained by the preservation of corrosive zinc products in the coating, which allows the creation of random barrier properties.

CURRENT APPROACH ON CUTANEOUS MELANOMA DIAGNOSTICS

2019 ◽  
Vol 65 (5) ◽  
pp. 638-644
Author(s):  
Mariya Ebert ◽  
Georgiy Gafton ◽  
Grigoriy Zinovev ◽  
I. Gafton
Keyword(s):  
Physical Examination ◽  
Cutaneous Melanoma ◽  
Growth Dynamics ◽  
Current Approach ◽  
Clinical Diagnostics ◽  
Skin Tumors ◽  
Steady Increase ◽  
Non Invasive ◽  
Early Stages ◽  
Other Information

Melanoma is on the first place in mortality among all skin tumors. Over the past 50 years, there has been a steady increase in the incidence of cutaneous melanoma compared to other types of tumors. Rates of 5-year survival are fairly high, if melanoma is diagnosed in the early stages, which requires adequate diagnostics and treatment. Melanoma diagnostic, especially in the early stages, can be problematic even for an experienced dermatologist. However, primary contact doctor can be any specialty. Melanoma and other skin tumors can be detected by physical examination during treatment for another disease. Phenotypic risks factors, anamnestic data, and physical examination data are important in cutaneous melanoma diagnostics. The sensitivity of clinical diagnosis during a visual examination by an experienced dermatologist is approximately 70 percent. However, dermascopy can significantly increase the accuracy of a clinical diagnostics. In recent years there has been an active research for new non-invasive methods and algorithms for cutaneous melanoma diagnostics. The main goal of non-invasive diagnostics is to determine need for biopsy. This decision should be based on a combination of clinical and dermascopic examinations and other information, including growth dynamics, symptoms and medical history. Thus, an adequate diagnostic of cutaneous melanoma, including non-invasive and invasive methods, is a simple and economically viable way to early detection of cutaneous melanoma and to reduce mortality from this aggressive disease.

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