Field deployable impedance-based corrosion sensor

Electrochemical impedance spectroscopy (EIS) has been used in various applications, such as metal corrosion monitoring. However, many conventional corrosion monitoring setups are bulky and inconvenient for in-situ testing. The purpose of this work is to reduce the size of the whole corrosion monitoring system. We utilized EIS to design a field deployable impedance-based corrosion sensor (FDICS), capable of performing in-situ EIS analysis. Experiments verified the sensor’s accuracy, and the results showed that the sensor performed similarly to a bench-top EIS machine when we tested on circuit models. Furthermore, we used the proposed FDICS to monitor a metal corrosion experiment and performed EIS. The result showed that the proposed FDICS is able to obtain the sample’s impedance spectroscopy, which could help researchers test its corrosion severity on a metallic sample in-situ. Compared to other bulky conventional setups, our device eliminates the design complexity while still showing insights into the corrosion reaction.

The effect of chemical treatment on the adhesion strength and structural integrity of the epoxy coatings

This research aims to investigate the effect of chemical treatment on the integrity of the epoxy coating on mild steel substrates. Grit blasted steel samples were chemically treated in 10 vol.% NaOCl solution, 10 vol.% CrCl3 and 30 vol.% H3PO4 - 5 vol.% HNO3 solutions prior to coating application. Post-cleaning surface morphology and chemical composition revealed the formation of oxidation products on steel surface. Under optimized conditions, a dry film thickness of 135 ± 3 m of epoxy coating was achieved. The CT2 sample (pre-treated with CrCl3) presented higher coating adhesion strength (4.12 MPa) and the lowest rust area of 0.03 % compared to other chemically treated samples during 720 hours of immersion in 5 wt.% NaCl solution. The coating degradation mechanism was evaluated by electrochemical impedance spectroscopy (EIS) after 24, 48, 72 and 120 hours of immersion in 3.5 wt. % NaCl solution. EIS analysis of the coated samples pretreated with NaOCl and CrCl3 solutions exhibited low water uptake and limited corrosion due to hindrance in the diffusion of ionic species through the coating. However, coated steel samples pretreated in acidic solutions displayed appreciable corrosion damage as confirmed from saly spray and immersion tests. For instance, the delamination of the CT3 and CT4 (acid pre-treated) coatings was confirmed from the EIS analysis., which represented the formation of a double layer and occurrence of faradaic (corrosion) reactions as the coating-substrate interface, resulting in 15 – 30% delamination in 120 hours of exposure.

EIS Analysis of Sulfur Cathodes with Water-Soluble Binder NV-1A for Lithium-Sulfur Batteries

The paper discusses the electrochemical behavior of a Li-S battery with a new water-soluble binder NV-1A. It is shown that the main contribution is made by the interface, which is formed on the lithium counter electrode. It is noteworthy that the nonlinear growth of the resistance of SEI layer during the discharge process correlates with the change in the resistance of charge transfer through the interface.

STUDY OF STRUCTURAL AND ELECTROCHEMICAL PROPERTIES OF 3-D MICROFLOWER-LIKE NICKEL HYDROXIDE

Recent work reported on nickel hydroxide chemically synthesized by simple cast effective chemical bath deposition method at room temperature. During reaction, nanoflakes developed and time enhance nanoflakes interlinked to form marigold like microflower which reveals from SEM. Structural properties analysis by XRD and FT-IR gives hexagonal crystal structure and presence of Ni-O bond to confirmation of deposition of Ni(OH) material. Highest value of specific 2 -1 capacitance of electrode at deposition time 90 min without aniline from Cyclic voltammetry is 553 Fg at scan rate 10 mV -1 -1 -2 -1 -1 s and from Galvanostatic charge discharge 215 Fg at current density 3 mA cm with 6.04 W h kg and 1687.5 W kg of energy and power density respectively. EIS analysis reveals least charge transfer resistance of 90min deposition time electrode.

Investigation on Microstructure, Nanohardness and Corrosion Response of Laser Cladded Colmonoy-6 Particles on 316L Steel Substrate

316L steel is predominantly used in manufacturing the components of high-pressure boilers, heat exchangers, aerospace engines, oil and gas refineries, etc. Its notable percentage of chromium offers resistance against corrosion and is mostly implemented in harsh environments. However, long-term exposure to these components in such environments can reduce their corrosion resistance property. Particularly at high temperatures, the oxide film formed on this type of steel reacts with the chloride, sulfides, sulfates, fluorides and forms intermetallic compounds which affect its resistance, followed by failures and losses. This work is focused on investigating the hardness, microstructure and corrosion resistance of the laser cladded Colmonoy-6 particles on the 316L steel substrate. The cladded specimens were dissected into cubic shapes and the microstructure present in the cladded region was effectively analyzed using the FESEM along with the corresponding EDS mapping. For evaluating the hardness of the cladded samples, the nanoindentation technique was performed using the TI980 TriboIndenter and the values were measured. The potentiodynamic polarization curves were plotted for both the substrate and clad samples at 0, 18, 42 and 70 h for revealing the corrosion resistance behavior. In addition, the EIS analysis was carried out to further confirm the resistance offered by the samples. The surface roughness morphology was evaluated after the corrosion process using the laser microscope, and the roughness values were measured and compared with the substrate samples. The result showed that the cladded samples experience greater hardness, lower values of surface roughness and provide better corrosion resistance when compared with substrate samples. This is due to the deposition of precipitates of chromium-rich carbide and borides that enhances the above properties and forms a stable passive film that resists corrosion during the corrosion process.

LSCF-CuO as Promising Cathode for IT SOFC

Infiltration of copper oxide towards LSCF was done in order to enhance cathode performance due to superior properties, including high electrical conductivity and high catalytic activity for the oxygen reduction reaction. Samples were synthesized at different temperatures using the sol-gel route. The TGA results showed that LSCF achieved complete perovskite formation when calcined above 600 °C and DTA showed the formation of lattice oxygen at 550 °C. XRD analysis showed no shifted peaks and nano size levels were achieved when samples were calcined at 700 °C and 800 °C. SEM and BET showed similar analysis patterns, where the particle size increased as the calcining temperature was increased. EIS analysis further verified that the polarization resistance of the sample calcined at 700 °C was as small as 0.161 Ω, compared to 1.524 Ω with a calcination temperature of 800 °C. The activation energy of LSCF-CuO was found to be 122.2 kJ/mol, which is much lower than for conventional LSCF.

Bi2S3/rGO Composite Based Electrochemical Sensor for Ascorbic Acid Detection

The engineering of an efficient electrochemical sensor based on a bismuth sulfide/reduced graphene oxide (Bi2S3/rGO) composite to detect ascorbic acid (AA) is reported. The Bi2S3 nanorods/rGO composite was synthesized using a facile hydrothermal method. By varying the amount of graphene oxide (GO) added to the synthesis, the morphology and size of Bi2S3 nanorods anchored on the surface of rGO can be tuned. Compared to a bare glassy carbon electrode (GCE), the GCE modified with Bi2S3/rGO composite presented enhanced electrochemical performance, which was attributed to the optimal electron transport between the rGO support and the loaded Bi2S3 as well as to an increase in the number of active catalytic sites. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis of Bi2S3/rGO/GCE demonstrate that the active Bi2S3/rGO layer on GCE plays an important role in the electrochemical behavior of the sensor. In particular, the Bi2S3/rGO/GCE sensor shows a wide detecting range (5.0–1200 μM), low detection limit (2.9 µM), good sensitivity (268.8 μA mM−1 cm−2), and sufficient recovery values (97.1–101.6%) for the detection of ascorbic acid.