Multielectrode Array Sensors Research Articles

The Study of Corrosion Behaviors of Carbon Steel Weldments and Their Inhibition in Simulated Pore Solution Using Multi-Electrode Array Technique

A multi-electrode array sensor was developed to study the corrosion behaviors of carbon steel weldments and the effectiveness of the NaNO2 inhibitor in carbonated pore solution. The sensor can simulate a complete weldment, and the measurement results can match well with the coupon immersion test. The galvanic corrosion between the weld area, heat-affected area, and base metal area, as well as the effect of nitrite corrosion inhibitor on the weld area, were observed by measuring the open circuit potential, coupling potential, and galvanic current. The results show that corrosion is likely to happen around the weld metal area and its adjacent heat-affected zone. The intensive galvanic currents can accelerate the localized corrosion, while NaNO2 can inhibit it.

An electroneurography-based assay for identifying injured nerve segment during surgery: design and in vivo application in the rat

Objective. Nerve injury is the main reason for nerve reconstruction surgery, during which the surgeon must determine the location of the injured nerve segment, resect it, and reconnect the remaining healthy nerve stump ends within a limited time. Given this importance, an assay needed to determine the exact location of the injured nerve segment, but no tool has yet fulfilled this need so that a visual inspection of the nerve is still the primary method of identifying the injured segment. Approach. We designed a flexible multi-electrode array sensor that records the electroneurographic signal (ENG) as the action potential elicited by electrical stimulation that propagates along the nerve upon both orthodromic and antidromic stimulation. Its utility was validated by in vivo experiments in injured sciatic nerves of rats. Main results. The results showed that the first post stimulus negative electroneurographic component (N1) is the most valid neural correlate, as its amplitude decreased, and latency increased as the action potential propagated across the injured segment. Gradual recovery of nerve conduction was observed when measured immediately, 7, and 30 d after injury. The locations of the identified injured segments were validated by histological findings. Significance. The sensor and the algorithm developed in this study are breakthroughs in surgical nerve assessment accomplished by determining the specific nerve segment that should be resected, enabling the optimal surgical outcome.

Study Pitting Corrosion of P110 Steel by Electrochemical Frequency Modulation Technique and Coupled Multielectrode Array Sensor

By using the electrochemical frequency modulation (EFM) technique, coupled multielectrode array sensor (CMAS), and other corrosion research techniques, the pitting corrosion behavior of P110 steel in oilfield formation water was studied. The results showed that serious pitting corrosion was observed on P110 steel at 90°C in oilfield formation water. The EFM and CMAS techniques could be used for monitoring or detecting pitting corrosion effectively. The average corrosion rates obtained by EFM and CMAS both decreased with time. At the first 12 h of the test the average corrosion rate was quite high and general corrosion occurred, and then the average corrosion rate decreased and the pitting corrosion was observed from the EFM results. The CMAS result showed that when the pitting corrosion happened, there were obvious localized anode and cathode pots on the metal surface that directly caused the pitting corrosion and might be related to the structure of the protective layer.

Investigation on the effect of polymer in vertical oil-water two-phase flow using nonlinear analysis

This paper is devoted to investigating the effect of polymer on vertical oil-water two-phase flow using nonlinear analysis. For the comparison of flow characteristics in oil-water flows with different polymer dosages, an experiment in a vertical upward pipe with 20mm inner diameter (ID) is conducted to obtain fluctuating signals of dispersed oil-in-water slug flow (D OS/W), dispersed oil-in-water flow (D O/W) and very fine dispersed oil-in-water flow (VFD O/W) using vertical multi-electrode conductance array sensor (VMEA). With the aid of recurrence plot, the effect of polymer on flow structure variation is qualitatively characterized. Then, recurrence quantification analysis and multi-scale weight complexity entropy causality plane (MS-WCECP) are respectively utilized to uncover the determinism and instability of the complex oil-water system with polymer addition. The results indicate that the recurrence plot can be effectively used to identify flow pattern and reveal the differences of flow structures in oil-water flows with and without polymer. The multi-scale weight complexity entropy causality plane can satisfactorily reflect the instability of polymer-added oil-water two-phase flow.

Spatiotemporal model-based estimation of high-density atrial fibrillation activation maps

Examination of activation maps using multi-electrode array (MEA) sensors can help to understand the mechanisms underlying atrial fibrillation (AF). Classically, creation of activation maps starts with detection of local activation times (LAT) based on recorded unipolar electrograms. LAT detection has a limited robustness and accuracy, and generally requires manual edition. In general, LAT detection ignores spatiotemporal information of activation embedded in the relation between electrode signals on the MEA mapping sensor. In this work, a unified approach to construct activation maps by simultaneous analysis of activation patterns from overlapping clusters of MEA electrodes is proposed. An activation model fits on the measured data by iterative optimization of the model parameters based on a cost function. The accuracy of the estimated activation maps was evaluated by comparison with audited maps created by expert electrophysiologists during sinus rhythm (SR) and AF. During SR recordings, 25 activation maps (3100 LATs) were automatically determined resulting in an average LAT estimation error of −0.66±2.00 ms and a correlation of ρs=0.98 compared to the expert reference. During AF recordings (235 maps, 28226 LATs), the estimation error was −0.83±6.02 ms with only a slightly lower correlation (ρs=0.93). In conclusion, complex spatial activation patterns can be decomposed into local activation patterns derived from fitting an activation model, allowing the creation of smooth and comprehensive high-density activation maps.

Effectiveness of Products in Managing Metallic Corrosion Induced by Cyclic Deicer Exposure: Laboratory Study Using Multielectrode Array Sensors, Electrochemical Impedance, and Laser Profilometer

AbstractA total of 12 multielectrode array sensors were utilized to assess the individual effectiveness of two corrosion inhibitors and one coating under cyclic deicer exposure conditions. There were four sensor groups, and each group consisted of nine-pin probes that were fabricated from 1008 carbon steel, 304 stainless steel, and 1100 aluminum, respectively. A total of two environmental exposure tests were conducted, in which 2.3% NaCl and 3.0% MgCl2 solutions were used as salt, respectively. The two tests each included eight environmental cycles and with 24 h per cycle. For all the exposed sensors, the most severe corrosion occurred at the beginning of the humidity stage. For sensors in the control group, MgCl2 exhibited a corrosion attack throughout the exposure period, whereas NaCl only exhibited an apparent corrosion attack during the humidity stage. Both the sensor corrosion rates and mass loss results indicate that the inhibitors had a much greater effect for MgCl2 than for NaCl. Although the coat...

Threshold Chloride Levels for Localized Carbon Steel Corrosion in Simulated Concrete Pore Solutions Using Coupled Multielectrode Array Sensors

Threshold chloride levels for localized corrosion of carbon steel material have been studied in three types of simulated concrete pore solutions: sodium hydroxide-potassium hydroxide (NaOH-KOH) with pH 11.6, calcium hydroxide (Ca[OH]2) with pH 12.6, and sodium hydroxide-potassium hydroxide-calcium hydroxide (NaOH-KOH-Ca[OH]2) with pH 13.3. The nonuniform corrosion rates of carbon steel were measured with coupled multielectrode array sensors (CMAS) when the chloride concentration was changed from 0.0005 mol/L to 1 mol/L in each solution. Open-circuit potentials were also measured from the coupling joint of the CMAS probes and electrodes made of rebar specimens immersed in the simulated pore solutions to verify the results from the CMAS probes.

Boric Acid Corrosion of Concrete Rebar

Borated water leakage through spent fuel pools (SFPs) at pressurized water reactors is a concern because it could cause corrosion of reinforcement steel in the concrete structure and compromise the integrity of the structure. Because corrosion rate of carbon steel in concrete in the presence of boric acid is lacking in published literature and available data are equivocal on the effect of boric acid on rebar corrosion, corrosion rate measurements were conducted in this study using several test methods. Rebar corrosion rates were measured in (i) borated water flowing in a simulated concrete crack, (ii) borated water flowing over a concrete surface, (iii) borated water that has reacted with concrete, and (iv) 2,400 ppm boric acid solutions with pH adjusted to a range of 6.0 to 7.7. The corrosion rates were measured using coupled multielectrode array sensor (CMAS) and linear polarization resistance (LPR) probes, both made using carbon steel. The results indicate that rebar corrosion rates are low (~1 µm/yr or less) when the solution pH is ~7.1 or higher. Below pH ~7.1, the corrosion rate increases with decreasing pH and can reach ~100 µm/yr in solutions with pH less than ~6.7. The threshold pH for carbon steel corrosion in borated solution is between 6.8 and 7.3.

A Review of Recent Patents on Coupled Multielectrode Array Sensors for Localized Corrosion Monitoring

The coupled multielectrode array sensor (CMAS) is an emerging technology for monitoring localized corrosion, such as pitting, intergranular attack, crevice corrosion, or other forms of nonuniform corrosion. The technique has been used for online, real-time corrosion monitoring in laboratories and field systems. In this paper, the patents related to the development of CMAS technology for localized corrosion monitoring are reviewed. These patents include applications in mapping or monitoring localized corrosion; methods for localized corrosion rate measurements; method to minimize internal current; improvement in electronics and software; planar CMAS probe; and high-temperature electrochemical sensors. Current and future developments of this corrosion monitoring technology are discussed. Keywords: Coupled Multielectrode Array Sensors, Corrosion monitoring, Localized corrosion, electrochemical sensor, multielectrode array, high-temperature electrochemical sensor, pitting, anodic electrodes, Multielectrode systems, electrode arrays, wire-beam electrode, Multi-phase corrosion, multielectrode sensors, carbon-coated electrodes, stainless steel

A Review of Recent Patents on Coupled Multielectrode Array Sensors for Localized Corrosion Monitoring

A Review of Recent Patents on Coupled Multielectrode Array Sensors for Localized Corrosion Monitoring

INVESTIGATION OF THERMO-PHYSICAL AND FLOW PROPERTIES OF CO2 HYDRATE SLURRY

A pilot CO2 hydrate slurry production system was built and tested. The density of CO2 hydrate slurry was experimentally investigated and the relation between the density and the solid fraction has been established. The apparent viscosity of water, CO2 solution and CO2 hydrate slurry was investigated with a XL7-100 online resonant viscometer. We find that when the solid mass fraction in slurry increases, the density and apparent viscosity of CO2 slurry also increase. CO2 hydrate solid particles contribute only slightly to the viscosity increase when the solid mass fraction increased from 1.59% to 28% from our experimental results. Higher solid mass fraction can be achieved when more CO2 gas is injected into the loop under suitable hydrate formation conditions. The pure hydrate's dissociation enthalpy was evaluated by Micro Differential Scanning Calorimetry system. The enthalpy of CO2 hydrate slurry mainly depends on solid mass fraction. Real-time coupled multielectrode array sensor probes were applied to measure the maximal localized corrosion rate of three different materials subjected to CO2 hydrate slurry and saturated CO2 solution in the temperature range of 274.15–291.15 K and pressure range of 2.5–3.0 MPa. For a long-term usage in a mixture of CO2 saturated aqueous solution and hydrate slurry environment, carbon steel materials are to be unacceptable from the corrosion resistance point of view. In contrast, stainless steel type 304L and copper 110 have presented very low corrosion rates.

An embedded multi‐parameter corrosion sensor for reinforced concrete structures

AbstractA prototype of an embedded corrosion sensor has been developed for assessing the corrosion status of reinforcing steel bar (rebar) in concrete. The integrated sensor unit includes an Ag/AgCl probe, a metallic oxide probe, a multi‐electrode array sensor (MAS), and a four‐pin (Wenner) array stainless steel electrode for chloride content, pH, microcell corrosion current, and localized concrete resistivity measurements, respectively. A stable solid probe was used as the reference probe in this unit to express the potentiometric measurement of chloride content and pH probes. In this study, the chloride and pH probes were calibrated in simulated pore solutions (SPSs) regarding temperature and pH fluctuations. The corrosion current results of the MAS probe in SPSs matched very well with those obtained by the linear polarization resistance technique, which was conducted on companion carbon steel specimens. A sensor prototype was embedded into a paste cylinder for long‐term performance evaluation. Up‐to‐date results show that the sensor probes exhibit excellent sensitivity and reliability through 1 year of monitoring. Continuous monitoring in the laboratory for extended periods is underway.

Internal Current Effects on Localized Corrosion Rate Measurements Using Coupled Multielectrode Array Sensors

Abstract Coupled multielectrode array sensors (CMAS) have been used for real-time monitoring of corrosion, particularly localized corrosion. The internal anodic current on the most anodic electrode...

High-Temperature Electrochemical Sensor for Online Corrosion Monitoring

Abstract Electrochemical sensors incorporating diamond-like carbon (DLC)-coated electrodes are effective tools for online, real-time corrosion monitoring at high temperatures. A vacuum-based chemical vapor deposition process was used to deposit a DLC thinfilm coating on the surface of the sensing electrodes. The chemical inertness of the DLC coating on the sensing electrodes produced a crevice-free electrode that can be used at temperatures above 100°C. In this paper, we present the coating deposition process for sensor electrodes and fabrication of coupled multielectrode array sensors (CMAS) for high-temperature, high-pressure applications. Probes were fabricated using uncoated and DLC-coated Alloy 22 (Ni-22Cr-13Mo-3Fe-3W [UNS N06022]) and titanium Grade 7 (Ti-0.2Pd [UNS R52400]) electrodes. The Alloy 22 probes were tested in high-temperature, high-pressure conditions in a pH 10 caustic solution. The measured nonuniform corrosion rate using the Alloy 22 probe with the DLC-coated electrodes was approximat...

A Review of Coupled Multielectrode Array Sensors for Corrosion Monitoring and a Study on the Behaviors of the Anodic and Cathodic Electrodes

Abstract Localized corrosion is often the cause of many failures and unplanned shutdowns in industry. For example, statistics have shown that more than 80 % of the corrosion-induced failures in the chemical processing industry are due to localized corrosion, rather than general corrosion. Thanks to the advancement in coupled multielectrode array sensors (CMAS) technology, localized corrosion rates can now be quantitatively measured. If interfaced with controllers, CMAS probes can be used to automatically control the dosing of corrosion inhibitors and reduce the cost for corrosion control. This paper presents an overview for the CMAS technology and the experimental data that verifies the working principles of the CMAS for localized corrosion rate measurement.

The perimeter measure analysis of chaotic attractor morphology of inclined oil-water two phase flow patterns

In two-dimensional phase space, the attractor morphology parameters of perimeter measures, such as area, lengths of long axis and short axis, are defined, and the variations of these parameters with the delay time are investigated. It was found that the growth rates of the above parameters do not change notably in the first zone during the attractor unfolding process, which is suitable for attractor morphology characterization. The classification effectiveness of this method is verified by applying it to simulating signals, such as sine signal, white noise, mixed signals and Lorenz signals. By the experiment of inclined oil-water two phase flow, the conductance signals were acquired from the vertical multi-electrode array sensor, and the water dominated inclined oil-water flow patterns are analyzed by using the attractor morphology parameters and we found that the growth rate of area is an invariant quantity of attractor morphology, which can give a good classification of dispersion of oil in water-pseudoslugs flow and dispersion of oil in water-countercurrent flow.

Development of Crevice-Free Electrodes for Multielectrode Array Sensors for Applications at High Temperatures

Abstract Coupled multielectrode array sensors (CMAS) have been used as online and real-time monitors for localized corrosion in both laboratory and field systems. In a CMAS probe, multiple miniature electrodes made of materials identical to the engineering component are used as sensing electrodes. The application of CMAS at high temperatures, up to 150°C in corrosive environments, however, is limited by degradation of the insulating mounting material, such as epoxy. Degradation of the mounting material can lead to crevice corrosion and causes an increase in the exposed surface area of the electrodes. In this study, the effectiveness of a diamond-like carbon film to protect the Alloy 22 (UNS N06022) electrodes in an acidic sodium chloride-sodium nitrate-potassium nitrate (NaCl-NaNO3-KNO3) salt mixture was demonstrated at 150°C. The average localized corrosion rate measured from the probe with coated electrodes in the NaCl-NaNO3-KNO3 salt mixture at 150°C was approximately 0.43 μm/y. In contrast, the averag...

Development of diamond-like carbon-coated electrodes for corrosion sensor applications at high temperatures

Coupled multielectrode array sensors have been used as online and real-time monitors for localized corrosion in both laboratory and field systems. Multiple miniature electrodes made of materials identical to the engineering component of interest are used as sensing electrodes. However, these devices have an upper operating temperature limit of approximately 70 °C because crevice formation between the electrode and the mounting material impairs their performance. In this paper, a crevice-free electrochemical sensor for corrosion monitoring at temperatures above 100 °C is presented. A diamond-like carbon thin film was deposited on the sensing electrodes using plasma immersion ion processing and its properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and laser Raman spectroscopy. The effectiveness of the diamond-like carbon film in protecting the Alloy 22 (Ni-22Cr-13Mo-3Fe-3W) electrodes in a corrosive NaCl–NaNO 3–KNO 3 salt mixture at 150 °C was demonstrated. The effective corrosion monitoring capability of the new electrochemical sensor at high temperatures was attributed to the pinhole-free microstructure, high electrical impedance, and high corrosion-resistance properties of the diamond-like carbon film.

Validation of localised corrosion model using real time corrosion monitoring in a chemical plant

A mechanistic model was developed and applied to predict the localised corrosion of a number of alloys in a plant process stream. In order to validate the model, multi-electrode array sensors (MAS) made from type 316L stainless steel and from two Fe–Ni–Cr–Mo–W alloys, AL6XN and alloy C–276, were installed in a side loop of a process stream in the chemical plant. The pitting corrosion rates measured from the probes were consistent with the plant equipment experience. The pitting rates obtained from the long term measurements were in good agreement with the actual corrosion rates obtained from post-test surface examination of the probes. The model successfully predicted the relative ranking of the alloys in this process environment. The pitting rates measured by the probes were consistent with model predictions.

Evaluation of the coupled multielectrode array sensor as a real-time corrosion monitor

Coupled multielectrode array sensors made of carbon steel and stainless steels were evaluated and compared with electrochemical noise (EN) sensors. Good correlations between sensor signals and solution corrosivity were observed for all multielectrode array sensors. Some correlation between the average pit index and solution corrosivity was observed for the carbon steel EN sensors, but not for the stainless steel EN sensors. The time-average noise resistances from the stainless steel EN sensors correlate well with solution corrosivity. There were, however, large random fluctuations and drifting for all EN signals, which make the EN sensors unreliable as real-time monitors.