bluuebunny/crossref_metadata_2025 huggingface dataset:
Miniaturization of Photothermal Cantilever Deflection Spectroscopy with an Electrical Readout
Authors: Kim Seonghwan , Lee Dongkyu , Thundat Thomas
Published: February 2020

Detection, differentiation, and quantification of trace amounts of chemical analytes with a portable device are of great interest in many applications such as energy, environment, law-enforcement, national security, and health. With the recent progress of micro/nanofabrication and system integration technologies, micro/nanoelectromechanical systems are regarded as very strong candidates to satisfy the current requirements of portable sensors such as high sensitivity, miniature size, multiple detection, low-cost, and low-power consumption. The enhancement in quality of life and economic growth are anticipated by realizing and exploiting high-performance portable chemical sensing systems in the near future. However, achieving this goal using the current approach based on the development of chemoselective interfaces is proving to be a challenging task, especially for the realization of reversible sensors at room temperature. Responses from a sensor with immobilized chemoselective interfaces often show interference due to the presence of other similar molecules and give false signals. This chemical selectivity challenge can be overcome by photothermal cantilever deflection spectroscopy (PCDS), which exploits the high thermomechanical sensitivity of a bi-material microcantilever. A bi-material cantilever responds to heat generated by non-radiative decay process when the adsorbed molecules are resonantly excited with infrared (IR) light. Monitoring the variation in cantilever deflection amplitude as a function of illuminating IR wavelength corresponds to the conventional IR absorption spectrum of the adsorbed molecules. In addition, the mass of the adsorbed molecules can be determined by measuring the resonance frequency shift of the cantilever for the quantitative analysis. This photothermal spectroscopy technique offers unprecedented opportunities for highly selective as well as sensitive chemical sensing without relying on chemoselective interfaces. However, conventional optical signal readout schemes employed for microcantilever sensors limit miniaturization and system level integration. Here, we demonstrate PCDS using a piezoresistive cantilever which can be easily miniaturized and integrated into a portable sensor platform.
Determination of the Antioxidant Capacity in Medicinal Plants, Using a Laccase Screen Printed-Type Biosensor
Authors: Rodríguez-Sevilla Erika , Ramirez-Silva Maria Teresa , Palomar-Pardavé Manuel , Romero-Romo Mario A. , Hernández-Arana Andres , Ibarra-Escutia Pedro
Published: February 2020

The immobilization of Laccase from Trametes versicolor (TvL) by means of entrapment, cross-linking and covalent bonding methods is analyzed through the development and characterization of amperometric screen-printed sensors for phenolic compounds. In order to do the immobilization with each of the methods stated, polyvinyl alcohol (PVA), glutaraldehyde (GA) and N-ethyl-N’-(3-dimethylaminopropyl)carbodiimide clorhydrate (EDC), were used respectively; the electrochemical characterization was carried out at (30.0 ± 0.5) °C and pH = 4.70 ± 0.01. The apparent Michaelis-Menten constant, Km
´, for the enzymatic oxidation of hydroquinone, HQ, to p-quinone, Q, was used as comparison parameter, to provide information on the enzymatic kinetic parameters, as well as the analytic parameter linked directly to the biosensor. After comparing the different immobilization methods, it became apparent that the best one was cross-linking at 40 °C, that gave the lowest Km
´ ((170.1 ± 3.2) µM), and HQ limit of detection ((17.0 ± 6.6) µM) values. The antioxidant capacity of real samples, infusion of medicinal plants, was evaluated using this biosensor.
Influence of Au Nanoparticle Surface Decoration on Highly Oriented SnO2 Nanorods/ZnO Hybrid Films for Gas Sensing Improved Performance
Authors: Carvajal Christian G , Pradhan Aswini K , Kadri Killani
Published: February 2020

Hybrid films containing SnO2 nanorods and ZnO michrorods were grown by a low-temperature vapor-liquid-solid (VLS) technique. Au nanoparticle decoration on the SnO2 and ZnO structures was succesfully carried out simultaneously by using a UV wavelength light source and a simple bath solution of HAuCl4·4H2O in ethanol. Surface morphologies and structural properties of the Au decorated SnO2 & ZnO structures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The Au decorating nanoparticles were found to be 10nm in average size showing an even dispersion along the hybrid films. Average sizes of the SnO2 nanorods and ZnO michrorods were reported previously elsewhere. Gas sensing measurements for acetone vapor, ethanol vapor, and carbon monoxide were carried out and compared using three different transducer films consisting in pure SnO2 film, undecorated SnO2 & ZnO hybrid film, and Au decorated SnO2 & ZnO hybrid film. Surface area and Au decoration dramatically influence the sensing device performance and this features are discussed in the present work.
Real-Time Impedimetric Detection of DNA Amplification By PCR Using Electrochemical Impedance Spectroscopy
Authors: Diaz-Cartagena Diana C , Gomez-Moreno Ramon , Cunci Lisandro , Diaz-Diaz Elimar M , Cunci Roman , Baerga-Ortiz Abel J. , Watkins James J. , Cabrera Carlos R
Published: February 2020

DNA sensors are innovative diagnostic tools that have gained broad acceptance in recent years. Different procedures have been used to develop these sensors. One of the most frequently used method is the self-assemble monolayer (SAMs) that provides advantages in terms of simplicity, efficiency and cost of electrode design. Gold surface modification with SAMs change the electrochemical capacitive behavior of their surface which can be measured by Electrochemical Impedance Spectroscopy (EIS). Tethering of ssDNA via SAMs techniques onto metallic Au surface provide a biosensing probe which is sensitive to changes on the surface, and these changes on the ssDNA conformation correlate to changes in the double layer capacitance (Cdl). Using this as the basis, a novel microchip with an interdigitated array electrodes was done and used as a real-time electrochemical biosensor for the detection of DNA amplification directly on its surface. The microchip was designed using a silicon/SiO2 substrate and gold thin film patterned by photolithography. The microchip is connected by a USB type A connector. In this device, the polymerase chain reaction (PCR) takes place on the surface interface, and the primer ssDNA tethered to the surface is elongated. Every modification, variation or alteration of the DNA on the surface of the electrodes result in changes in the Cdl and measured by EIS having a non-faradaic and label-free detection. The recognized sensitivity of electrochemical platforms and the well-known specificity of exclusive primers provide portability, reliability, rapidness, and accuracy in a robust biosensor microchip. Moreover, by avoiding the use of optical labels we are able to measure complex or unpurified biofluid samples without the need of extensive purification. All these features will have a tremendous impact on the biomedical science filling the absence of methods that can detect DNA in real-time and in a direct readout of crude biological fluids.
MEMS Based Eit Technology for Non-Invasive Breast Cancer Diagsnostics
Authors: Khosla Ajit
Published: February 2020

Non-invasive and radiation free medical imaging modalities for breast screening is increasingly in demand as the health care industry is taking a paradigm shift from the traditional “treating the sick” to “keeping people healthy” model. To address this need, we are developing a Nano Electrode Array based Electro Impedance Tomography (EIT) device.

The objective of this device is to become the leading solution for accurate and cost-effective non-invasive and radiation free early breast cancer detection medical imaging modality.This will be the first medical imaging device to use nano-electrode array embedded in flexible textile as sensors (fabricated via MEMS processes) [1, 2, 3, 4, 5,6], scan across a wide frequency spectrum and allow scanning of both breasts simultaneously. In addition, it is also the first device that simultaneously allows the scanning of lymph nodes located under the arm, a feature which is of value to oncologists tracking progression and treatment of cancers.

References:

D. Chung, A. Khosla, et al, “Flexible Ag/AgCl electrodes for applications in tissue Electrical Impedance Scanning (EIS)” Journal of The Electrochemical Society, 161 (2) B3071-B3076 (2014)

A. Khosla and B. L. Gray, “Preparation, characterization and micromolding of multi-walled carbon nanotube polydimethylsiloxane conducting nanocomposite polymer”; Materials Letters Volume 63, Issues 13-14, 31 May

2009, Pages 1203-1206.

A. Khosla, B.L. Gray, “CONDUCTIVE ELASTOMERIC MATERIAL AND USES THEREFOR“ US Patent No. 61/113998- Issued.

A. Khosla, and B. L. Gray; “Micropatternable Multifunctional Nanocomposite Polymers for Flexible Soft NEMS and MEMS Applications” ECS Trans. 2012 volume 45, issue 3, 477-494.

Matthew Giassa, A. Khosla, B. L. Gray, Ash Parameswaran, Kirpal Kholi, Ramani Rameseshan. “Applications for Low Frequency Impedance Analysis Systems.”, Journal of Electronic Testing, Volume 26, Number 1, 139-144, 2010.

A. Khosla, and B. L. Gray; "Fabrication and properties of conductive micromoldable thermosetting polymer for electronic routing in highly flexible microfluidic systems", Proceedings of SPIE Vol. 7593, 759314 (2010)
On-Line Preconcentrator on a Glass Capillary with Electrokinetic Trapping Technique
Authors: Lee Jeong Hoon , Yoo Yong Kyoung , Han Sung Il , Lee Junwoo , Chae Myung-Sic , Hwang Kyo Seon
Published: February 2020

In proteomics, the needs for concentrating the low-abundant molecules from the target samples are rapidly increased, since the concentration of low abundant ones might fall below the detection limit of biosensors.1 In many cases, the samples are needed with several separation steps so that the preconcentration step is even more important when using microfluidic sensing systems.

Recently, protein preconcentrator are intensively investigated with micro/nanofluidic channel networks.2
,
3 More recently, the microfluidic chips with perm-selective ion nanoporous material have been developed for enhancing their performance4. The microfluidic preconcentrator based on electrokinetic trapping technique was intensively studied with PDMS, however, the surface of PDMS is unstable, which lead to inefficient use of electrokinetic trapping.

Here, we suggest the capillary based preconcentrator for collecting target proteins. It is well-known that the capillary has well-defined surfaces and could be connected easily with other analytical equipment. For this, we developed preconcentrator on a glass capillary simply by coating the ion-permslective membrane inside the glass channels. For operating protein preconcentration, we applied 20 V at both side electrodes in reservoir and tested the negative pressures to operate the ICP, then observed ion concentration polarization formed around ion permselective nanoporous material pattern. We tested the BDNF protein directly connected from the inserting tube in a mouse and measured real-time BDNF protein quantities with times

This simple and powerful method can provide a high sensitivity and a high reliability for preconcentration of other analysis equipment such as electro-spray components for the Mass Spec applications.

References

1. J. H. Lee and J. Han, Microfluid Nanofluid 9, 973-979 (2010).

2. Y.-C. Wang and J. Han, Lab Chip 8, 392 - 394 (2008).

3. J. H. Lee, Y.-A. Song and J. Han, Lab Chip 8 (4), 596-601 (2008).

4. J. H. Lee, B. D. Cosgrove, D. A. Lauffenburger and J. Han, J. AM. CHEM. SOC. 131, 10340-10341 (2009).
Electrochemical Behavior of Carbon and Thermo-Treated Steel Rebars Embedded in Concrete Exposed to Chlorides
Authors: Martínez-García Ricardo Adrián , Rivera-Corral Jesús Octavio , Fajardo Gerardo
Published: February 2020

One of the most used materials to reinforce concrete structures is the carbon steel rebar, however raw materials to produce carbon steel according to ASTM-A-615 standards are have become more expensive, so most of the production of this type of steel reinforcement is made from ferrous metal waste material; but, their physical and mechanical properties are barely sufficient for the requirements that the applications demand and the fact of using raw materials of a known stoichiometric composition to improve them can result in an increase of the cost production, so the implementation of heat treatment has been the most feasible alternative to achieve the required quality checks at reasonable prices.

There is a great quantity of electrochemical data related to the mild steel rod, but the heat treatment produces a martensite outer layer, which may cause electrochemical differences. For this reason the main objective of this work was compare the electrochemical behavior between two different types of reinforcement, such as carbon steel and thermo-treated steel by QTB (Quenching Temperature Bar) process. The research was conducted in an accelerated exposure environment through immersion-drying cycles, using reinforced concrete specimens fabricated with water/cement ratios of 0.45 and 0.65.

These specimens were monitored through electrochemical tests, such as the half-cell potential (HCP) and the linear polarization resistance (LPR). Finally the determination of the critical chloride concentration was performed with a potentiometric titration. A critical chloride concentration of 0.45% and 0.73% for total chlorides by weight of cement were obtained for thermo-treated steel and carbon steel, respectively; where the critical chloride concentration is parameter which defines the activation for a reinforced concrete structure. In this case the activation time was different, but the electrochemical results obtained in all the exposure period for both of the two reinforcing steels were similar. The results were used for develop two explications about of the activation time differences between the two reinforcing bars.
Corrosion Inhibition of C38 Steel in 1M HCl Media By Amazonian Tree Alkaloidic Extract: Electrochemical and Phytochemical Study of Xylopia Frutescens Aubl
Authors: Chevalier Maxime , Sutour Sylvain , Roos Christophe , Lebrini Mounim
Published: February 2020

The present report continues to focus on the broadening application of plant extracts for metallic corrosion control [1and 2] and reports on the inhibiting effect of the Xylopia frutescens alkaloidic extract on the corrosion of C38 steel in 1 M hydrochloric acid. This extract presents mainly aporphinoid alkaloids, with nitrogen, oxygen, and aromatic rings. The corrosion inhibition’s is studied by polarization curves and electrochemical impedance spectroscopy (EIS). Constant phase element parameters of EIS are graphically calculated for better data precision. Studies on the phytochemical constituents of the total extract were also established and the active(s) molecule(s) are identified by NMR spectroscopy.

The total alkaloid extract of Xylopia frutescenswas found to be an inhibitor for C38 steel corrosion in 1 M HCl solution and its inhibition efficiency increased with increasing concentration. The study showed that the inhibition behavior of the crude extract is due to the presence of aporphinoid alkaloids in the crude extract.

1- F.Suedile,etal., Corrosion inhibition of zinc by Mansoa alliacea plant extract in sodium chloride media: Extraction, Characterization and Electrochemical Studies, Electrochim. Acta (2014), http://dx.doi.org/10.1016/j.electacta.2013.12.070

2- M. Chevalier, et al., Enhanced corrosion resistance of mild steel in 1 M hydrochloric acid solution by alkaloids extract from Aniba rosaeodora plant: Electrochemical, phytochemical and XPS studies, Electrochim. Acta (2013), http://dx.doi.org/10.1016/j.electacta.2013.12.023
Effect of Nano-Encapsulated Corrosion Inhibitors on Self-Healing Corrosion Protection of Steel Sheets
Authors: Choi Ha Na , Kim Jong Sang , Park Jong Myung
Published: February 2020

A nano-encapsulation system of organic corrosion inhibitors has been designed, which is capable of improving the self-healing corrosion protection without degrading the barrier protection of the coating layers. Core-shell nanoparticles loaded with six types of amine corrosion inhibitors such as ethanolamine, 5-amino-1-pentanol, diethanolamine, triethanolamine, propylamine and dipropylamine, were synthesized by multi-stage emulsion polymerization. Amines were successfully encapsulated into nanocapsules by reacting with carboxylic acid in core and shell polymer during alkalization swelling process. Water-soluble amines were effectively introduced in nanocapsules, and the basicity was the most predominant parameter for amine encapsulation. In alkaline condition, the encapsulated amines were generally well released and the release of the encapsulated amines was pH dependent regardless of the exposure time. In addition, the molecular structure and aqueous solubility were critical factors in the release behaviors. Linear amines and highly water-soluble amines were more easily released to the environments from inside capsules than branched and water-insoluble ones. The nanocapsules were incorporated into the coating resin and were coated on cold-rolled steel sheets to investigate corrosion protection efficiencies. The corrosion inhibitive efficiencies of the nanocapsule-containing coating layers were evaluated by semi-immersion tests and electrochemical tests, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). The organic coatings with inhibitor-loading nanocapsules showed better corrosion performance than the organic coating with inhibitor-free nanocapsules. Among six amines used in this study, 5-amino-1-pentanol, diethanolamine and triethanolamine exhibited self-healing anti-corrosion performance with recovering coating resistance. The coating resistance of the coating film gradually decreased and then increased via the self-healing corrosion protection of amines release from the nanocapsules. On the other hand, ethanolamine, propylamine and dipropylamine exhibited a rapid drop in the coating resistance, and the resistance continued to decrease without self-recovery. The inhibition efficiencies of encapsulated amines were affected by both intrinsic inhibition activities of amine and encapsulation/release behaviors.
Corrosion Mechanism of Nicrwmo Coating Deposited by HVOF
Authors: Achem Calahorra Jamnie Yazmin , Tiburcio Citlalli Gaona , Estupiñan Francisco , Estrada Ariadna Trujillo , Poblano Salas Carlos , Calderón Facundo Almeraya , Cabral Miramontes Jose Angel
Published: February 2020

Coatings Ni-Co-W- Mo have excellent resistance to abrasion and wear, further have good resistance to corrosion in acid and alkaline aqueous media. The thermal spraying technique Oxy-Fuel high speed (Hight Velocity Oxygen-fuel) was used to deposit the coating of the alloy on 304 stainless steel substrates. Such coating was evaluated using electrochemical resistance to linear polarization and curves cyclic polarization in HCl solution, NaOH and distilled water, to compare a function of pH the corrosion resistance and the corrosion mechanism that occurs in this type coatings. The results show that the coating has similar corrosion resistance to the substrate used.
Electrochemical Behavior of Steel Covered with Corrosion Products of Zinc
Authors: Tada Eiji , Katakami Shinya , Nishikata Atsushi
Published: February 2020

Corrosion protection mechanism of galvanized steel is mainly attributed to galvanic action of zinc and barrier effect of corrosion products of zinc.1)-2) Especially, it is said that corrosion products of zinc offer some corrosion protection to steel even after sacrificial dissolution of metallic zinc.3) In this study, electrochemical behavior of steel covered with zinc corrosion products was investigated to clarify protection mechanism for steel corrosion by zinc corrosion products.

A galvanic couple of Zn/steel, consisting of a steel substrate and a zinc layer, was used to prepare steel covered with zinc corrosion products. The zinc layer with 2 mm in width and 2 um in thickness was prepared by electrodeposition of zinc on the center of the steel substrate. The surface ratio of steel and zinc was 6:1. The Zn/steel couple was immersed in 1 M NaCl or 1 M MgCl2until the zinc layer dissolved completely. The zinc corrosion products formed on the steel substrate were observed and analyzed by SEM-EDX and Raman spectroscopy. Micro-electrochemical technique was employed to measure anodic and cathodic polarization curves for the steels covered with zinc corrosion products. The test solution for the polarization measurements was 0.1 M NaCl.

From the results of surface observation, precipitation morphology of zinc corrosion products changed depending on the types of the electrolyte solutions and the distance from the zinc layer. In case of 1 M NaCl, zinc corrosion products precipitated mainly around the zinc layer and the amount of the products decreased with increasing the distance from the zinc layer4)-6). The zinc corrosion products were confirmed to be zinc hydroxide and simonkolleite. It was found that cathodic reaction for steel covered with these corrosion products was inhibited. On the other hand, in case of 1 M MgCl2, precipitation morphology of zinc corrosion products was different from that in 1 M NaCl and the corrosion products containing Mg were formed on the steel a certain distance away from the zinc layer. The results of electrochemical polarization tests showed that anodic kinetics was suppressed on the steel covered with the corrosion products containing Mg.

References

X. G. Zhang, J. Electrochem. Soc., 143 (1996), 1472.

M. Matsumoto, J. Surf. Finish. Soc. Jpn., 57 (2006), 25.

S. Fujita and D. Mizuno, Corros. Sci., 49 (2007), 211.

E. Tada, K. Sugawara and H. Kaneko, Electrochim. Acta, 49 (2004), 1019.

E. Tada, S. Satoh and H. Kaneko, Electrochim. Acta, 49 (2004), 2279.

E. Tada and H. Kaneko, Corros. Sci., 52 (2010), 3421.
Inhibition of Carbon Steel in Cooling Water Systems by Nicotinamide
Authors: Branzoi Florina , Branzoi Viorel , Iordoc Mihai
Published: February 2020

Nicotinamide as organic inhibitor has anticorrosive properties and for this reason, was used for cooling water systems protection. The inhibition activity analysis of this new organic inhibitor was made by assuming that the mechanism of inhibition by organic molecules is chemisorptions and that the energetic of the corrosion process per se is unaffected by the addition of substituents on the parent compound. We presume that, this organic inhibitor, nicotinamide, inhibit corrosion of carbon steel by a protective mechanism, forming insoluble iron complexes and repairing the porous oxide layers. The methods employed were potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and metallurgical microscopy techniques. The addition of the organic inhibitors led in all the cases to inhibition of the corrosion process. The inhibition efficiency was high in all the studied cases. The corrosion parameters obtained from polarization curves and from EIS spectra are in good concordance and point out the inhibitory action of nicotinamide. The adsorptions of the organic compounds on the carbon steels surface obeyed Langmuir’s isotherm. Further characterization using Fourier transform infrared spectroscopy (FT-IR) demonstrates the adsorption of organic inhibitors and the formation of corrosion products on the carbon steels surface. The inhibition process was attributed to the formation of the adsorbed film on the metal surface that protects the metal against corrosive agents. The EIS measurements have confirmed this protection and pointed out the formation of adsorption layers on the electrode surface.
Electrochemical Study of Corrosion in High Temperature Molten Salts
Authors: Garcia-Diaz Brenda L. , Olson Luke Christopher , Martinez-Rodriguez Michael J. , Fuentes Roderick Eliel , Gray Joshua R.
Published: February 2020

Concentrating solar power systems are projected to need to produce energy with a cost of $0.06 / kWh when implemented on a very large scale. It is generally believed that temperatures of the heat transfer fluids will need to be higher than 800oC to drive an advanced Brayton cycle or Rankine cycle with superheated steam to reach this target. However, current state-of knowledge of corrosion science indicates a lack of published data on the impact of molten salts at temperatures above 800°C on corrosion of molten salt contacting materials such as steels or high temperature alloys and ceramics. This work investigates the corrosion mechanism of selected alloys and ceramics in chloride and fluoride molten salts used for high operating temperature heat transfer fluids using a combination of electrochemical techniques, theoretical calculations, and thermodynamic predictions. The electrochemical characterizations included linear polarization resistance scans, electrochemical impedance spectroscopy, and cyclic potentiodynamic polarization. Results show that the Fe-Ni-Cr alloys tested have high general corrosion and require corrosion inhibition. Advanced materials, such as SiC-SiC and TZM, have been shown to have much lower corrosion and good passivation behavior. Experimental tests using coupon immersion in the molten salts support the mechanism determined from electrochemical testing that the main element being oxidized is Cr. Analysis of samples also indicates selective Cr oxidation creates porous layers in the sample. The electrochemical impedance tests suggest that the corrosion is diffusion controlled.
Corrosion of High Temperature Materials in Fluoride and Chloride Molten Salts
Authors: Fuentes Roderick Eliel , Olson Luke Christopher , Martinez-Rodriguez Michael Joe , Gray Joshua R. , Garcia-Diaz Brenda Lee
Published: February 2020

Concentrating solar power (CSP) systems that can operate at higher temperatures than 800°C can achieve higher efficiencies and power production using high temperature power cycles. Operating at these temperatures requires identifying heat transfer fluids and materials for construction of heat transfer systems that will provide good operating characteristics and long system lifetimes. Advanced power cycles such as the supercritical CO2 Brayton cycle can operate above 800°C and molten salts are one of the best options to transfer heat at these conditions due to their very high boiling points and good heat transfer properties. However, a potential drawback with using molten salts at high temperatures is materials corrosion. Therefore, it is important to identify pairs of heat transfer materials and molten salts that will have the mechanical properties and chemical stability to provide long system lifetimes. Several alloys that can be used for high temperature operation includes alloys with high nickel and chromium content, such as Haynes 230, and high cobalt and chromium content, such as Haynes NS-163. However, weight loss by dealloying of chromium from high temperature alloys containing chromium was observed when exposed to FLiNaK at 850°C for 500 hrs1. In this work, several high temperature alloys such Haynes 230 and NS-163, TZM and a SiC/SiC composite were exposed to molten KCl-MgCl2 and FLiNaK at temperature 750, 850 and 950°C for a long term period. The alloys were examined via SEM/EDS post corrosion at the surface and cross-section to account for the corrosion attack and element depletion from bulk. The salts were analyzed via ICP-OES to quantify the elements that were depleted and diffused into the salt.

Reference:

1. L.C. Olson, J. W. Ambrosek, K. Sridharan, M. H. Anderson and T. R. Allen, Journal of Fluorine Chemistry, 130(1), 67-73 (2009).
High Temperature Electrochemical Evaluation of Ni Based Coatings Deposited by Laser Ablation
Authors: Estrada Ariadna Trujillo , Miramontes Jose Angel Cabral , Aguilar Pedro Antonio Márquez , Hernández Adalberto Castro , Robledo Patricia Zambrano , Tiburcio Citlalli Gaona , Calderón Facundo Almeraya
Published: February 2020

INTRODUCTION

Among the wide variety of coating applications Laser Ablation [1,2], we can find an alternative for the lifetime of the materials used in aggressive media, such as molten salts which cause various damages and losses are substantially represented in the industry [3,4].

METHODOLOGY

SA213-T22 the steel is used as substrate for the deposition of coatings based Ni a shot blast treatment before the coating is applied leaving the surface to which this list to be anchored correctly. The electrochemical tests were done with a 3-electrode cell (RE, AE w1) [3] at two temperatures 25 ° and 700 ° C.

RESULTS

Figure 1 shows two linear polarization can be observed at a higher temperature than the corrosion rate decreases and the potential Icorr is more active presents.

CONCLUSIONS

The laser coatings represent an alternative to tackle the process of high temperature corrosion by molten salts as these may have greater strength than other materials.

Electrochemical techniques are a useful tool for assessing coatings by laser Ablation molten salt alternative.

REFERENCES

[1] Ferrari, B., R. Moreno, T. Benito, M. T. Larrea, and J. C. Fariñas. Revista de Metalurgia 34, no. Extra (1998): 22-26.

[2] M. Badrossamay, T.H.C. Childs, Volume 47, Issue 5, April 2007, Pages 779-784, ISSN 0890-6955

[3] Almeraya, F., A. Martinez-Villafañe, C. Gaona, M. A. Romero, and J. M. Malo. Revista de metalurgia 34, no. 1 (1998): 11-17.

[4] Tristancho, José Luis, Facundo Almeraya, and José Chacón. Scientia et Technica 3, no. 46 (2010): 163-167.
Electrochemical Analysis of Temperature, Concentration and Velocity Effects in Naphthenic Acid Corrosion of 5%Cr-1%Mo Steel
Authors: Escorcia Rojas Kely Margarita , Laverde Cataño Dionicio Antonio
Published: February 2020

Abstract:

When heavy oil are submitted to high temperature and stirring conditions as found in the furnaces that belongs to preheating-section in refining units, corrosive mechanisms such as produced by naphthenic acids evolves to attack the material. The corrosion resistance of steels that are used in these applications is improved by adding elements such as Cr and Mo, since these tends to form oxides that change the kinetics of corrosion and provide major stability to the material structure.

The temperature, velocity and naphthenic acids concentration effects in the corrosive mechanism of 5%Cr-1%Mo steel were studied in a dynamic autoclave by Electrochemical Impedance spectroscopy (EIS), Linear Polarization Resistance and Potentiodynamic Polarization Curves with an electrochemical cell of three electrodes: reference and counter electrode was made of Au and working electrode was 5%Cr-1Mo sample. The sample was exposed to mineral oil-naphthenic acids solutions to different concentrations (0.0-3.0 mg KOH/g) and 200 psi pressure. Contrary to the velocity effect, the temperature has a huge influence in the steel corrosion: to 180°C the steel exhibits lower corrosion rate, however, increasing temperature promotes the thermal composition of complex naphthenic acids, reflecting a reduction in resistance charge transfer between metal-electrolyte Rm/e, increasing the corrosion rate. Moreover, the temperature is closely related to the concentration acid effect, since the kinetics of corrosion changes significantly when the system is subjected to higher temperatures.

These results were complemented with surfaces characterizations by Scanning electron microscopy and dispersive X-ray analysis (SEM/EDX) and were observed major attacks on steel to higher temperatures. Moreover, the electrolytes were characterized by Fourier transform infrared spectroscopy (FTIR) and mass spectrometry techniques.
Electrochemical Impedance Study on Dissolution of Cu-Zn Alloy in Fresh Water
Authors: Hoshi Yoshinao , Tabei Kozue , Shitanda Isao , Itagaki Masayuki
Published: February 2020

The brass (Cu-Zn alloy) is widely used for the water pipe of constructional plant and the joint of the device material. One of the corrosion problems of Cu-Zn alloy is the dezincing, which is the selective dissolution of Zn from Cu-Zn alloy. The fundamental studies of anodic dissolution of Cu-Zn alloy were reported by Pickering et al. (1-3). They indicated that a porous Cu-rich layer was formed on the surface of Cu-Zn alloy due to the preferential dissolution of Zn from Cu-Zn alloy. They proposed the two types of the dissolution mechanisms, which were simultaneous and selective. However, the stability of the Cu-rich layer formed on the Cu-Zn surface has not been clarified yet.

In the present study, the dissolution of Cu-Zn alloy in the fresh water was investigated by an electrochemical impedance spectroscopy (EIS). The measurement of the electrochemical impedance was performed by three-electrode system. The working electrode (0.785 cm2) was Cu-Zn alloy (Cu-35at%Zn) and the counter electrode was the platinum wire. The KCl-saturated silver/silver chloride electrode (SSE) was used as the reference electrode. All the potentials in this study were referred to SSE. In order to investigate the stability of the Cu-rich layer formed on the surface of Cu-Zn alloy, the formation of the Cu-rich layer was conducted as follows. The Cu-Zn alloy (Cu-35at%Zn) was abraded by #1200 emery paper under running water. Then, the galvanostatic polarization of Cu-Zn alloy was measured at 1.0 mA/cm2 for 24 h. The electrolyte solution was 0.5M NaCl containing 5mM NaHCO3. The temperature of the electrolyte solution was keep at 60 oC by thermostatic bath.

The impedance spectra of the Cu-Zn alloy before and after the formation of Cu-rich layer on the surface of the Cu-Zn alloy were measured to examine the stability of the Cu-rich layer. In addition, the results of the rest potential and the anodic polarization curve were also discussed in the present study.

Reference

1. H. W. Pickering and C. Wagner, Journal of the Electrochemical Society, 114, 698 (1967).

2. H. W. Pickering, Journal of the Electrochemical Society, 115, 143 (1968).

3. H. W. Pickering and P. J. Byrne, Journal of the Electrochemical Society, 116, 1492 (1969).
Potential Scanning Impedance Spectroscopy to Investigate Dissolution Mechanisms of Iron
Authors: Itagaki Masayuki , Isobe Koichiro , Hoshi Yoshinao , Shitanda Isao
Published: February 2020

Electrochemical impedance spectroscopy (EIS) is powerful method to analyze dissolution mechanisms of metals because time constants for elementary reaction steps and formation of reaction intermediate can be discriminated. Impedance spectrum is generally measured by using frequency response analyzer whose principle is on the basis of Fourier transformations of sinusoidal input and output signals. In the present paper, we employ a wavelet transformation to determine impedance spectra of dissolving iron electrode because the wavelet transformation gives the power spectrum densities with recording the time and the time variation of the spectra can be discussed. We used complex Morlet mother wavelet in order to obtain the complex number data in the frequency domain. The time-dependent impedance of the dissolving iron electrode can be determined by calculating cross spectra of the wavelet coefficients of current and potential signals. We developed potential scanning impedance spectroscopy (PSIS) using the impedance determination by wavelet transformation. By PSIS, we can obtain the successive impedance spectra with measuring the potentiodynamic polarization curve of metal electrode simultaneously, and discuss the dissolution mechanisms of iron in aqueous solutions.
Study of the Oxygen Reduction Reaction on the Coupled Galvanic Carbon Steel - Stainless Steel
Authors: Pérez-Quiroz José Trinidad , Genescá Llongueras Juan , Pérez-López Tezozomoc , Rendón-Belmonte Mariela , Terán-Guillen Jorge , Martínez-Madrid Miguel
Published: February 2020

The main objective of this work is to study the electrochemical behavior of galvanic coupling between carbon steel, CS, and stainless steel, SS, in an alkaline environment simulating the conditions prevailing in a repaired structure in which stainless steel rebar’s will be an option. Previously research conducted in different parts of the world on this subject reach agreement with the fact that AISI 304 SS and 316 SS embedded in concrete offers high corrosion resistance in aggressive environments but only for the case of new structures, and no further explanation has been given on the behavior of SS when in contact with CS. Galvanic coupling between these two metals should increase the corrosion process of the more anodic, CS in this case, but this phenomenon does not occur in practice.

Galvanic coupling was investigated by means of the electrochemical coulostatic technique. Tests performed allow determining the Tafel slopes of anodic and cathodic processes. The Tafel slope values obtained show that the process is being controlled by the reduction of oxygen, O2 in the environment where the samples were placed. On the basis of these kinetic parameters, a mechanism for the corrosion process is proposed in which the rate determining step would be O2 mass transfer process. The diffusion of O2 would take place through a formed oxide film, passivating in nature. Due to the formation of this oxide film, the cathodic oxygen reduction reaction, ORR, on stainless steel surface would be very slow. The high polarization of ORR rate would be the factor controlling the whole process, then minimizing the risk of damage by galvanic corrosion, demonstrating the feasibility of using stainless steel in the repairing of concrete structures.
Electrochemical Evaluation of TiO2, Cerium and Iron TiO2 Based Nanofibers Coatings in Copper and Copper Alloys Substrates
Authors: Rodriguez-Acuña Fausto , Aguilar-Campuzano Elivet , Hernandez-Escampa Marco , Hernandez-Gallegos Miguel , Menchaca Carmina , Uruchurtu Jorge
Published: February 2020

Nanofibers have very well known applications in several fields like medicine, textile industry and energy systems. They can be produced by different techniques including electrospinning. In this work, a process for obtaining TiO2 cerium and iron TiO2 nanofibers with a mesoporous structure was performed in order to produce coatings and evaluate their properties. The formation of porous structures using titania, mixed titania/ceria and mixed titania/iron oxides precursor solutions was achieved with a polymer gel templating technique. The nanofibers were prepared with a sol–gel solution containing a mixture of poly (vinyl pyrrolidone) [PVP, Mw 1 300 000], titanium tetraisopropoxide [Ti(O-i-Pr)4], a triblock copolymer Pluronic F127, cerium(III) nitrate hexahydrate [Ce(NO3)3∙6H2O] and iron oxides using the electrospinning technique. The synthesis process was carried out afterward to promote the crystallization and phase transformation to anatase, as well as to remove the polymer via calcination in air at 500 °C. Scanning electron microscopy (SEM) revealed the average diameters of the resulting nanofibers were in the 70 nm to 200 nm range, depending on the preparation conditions. The aim of this work was to evaluate the electrochemical behavior of TiO2, cerium and iron TiO2based nanofibers coatings applied to copper and copper alloys surfaces. In order to achieve this goal, an experimental procedure was designed which allowed to simulate the degradation of the coatings in corrosive environments. The techniques used included electrochemical noise measurement, electrochemical impedance spectroscopy and potentiodynamic polarization.
Evaluation of Atmospheric Corrosion in the City of Tuxpan Veracruz
Authors: Gallardo Castán Ernesto , Lugo Islas Gabriela , Galicia Badillo Aurora , Ramírez Reyes José Luis , Mercado Bahena Iris Graciela , Alarcón Molina Luis Alexis , García Navarro Norma , Pérez Téllez Juan
Published: February 2020

Tuxpan is a port with economic and industrial important activity, has subject to the process of atmospheric corrosion of metal structures such as boats, ships, oil platforms and Thermoelectric. The main purpose of this paper is to evaluate the Atmospheric Corrosion of Tuxpan Veracruz, it was necessary to install a display panel with carbon steel specimens (Ac -R), galvanized steel (zinc ), aluminum and copper in order to evaluate them in every season by electrochemical methods (electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and potentiodynamic polarization curves (CP) ) and at the end of the year by gravimetric techniques as established by CLIMAT and ISO methodology. The results show the aggressiveness of the marine atmosphere, mainly zinc and carbon steel due to aggressive agents such as chlorides and SiO2 (silica). XRD analysis shows the presence of metal oxides formed on the metal substrate surface.
Microstructural and Electrochemical Characterization of Ti6Al4V Alloy
Authors: Flores-Álvarez José Fernando , Rodriguez-Gomez Francisco Javier , Onofre-Bustamante Edgar , Roncagliolo Barrera Paola
Published: February 2020

The present work is an electrochemical study of Ti6Al4V alloy and TiO2 films obtained by thermal oxidation technique, and the use of cerium salt as a corrosion inhibitor. The electrochemical characterization was performed in phosphate-buffered saline (PBS) solution using the techniques of linear polarization and electrochemical impedance spectroscopy, and present phases’ characterization technique by scanning electron microscopy (SEM).

The protective capacity against corrosion of films using heat and cerium salt as corrosion inhibitor depends on the thickness of the oxide layer formed on the surface.

Blanks and thermally oxidized at 700 ° C for one hour and cooled in the oven for 24 hours samples, and samples heat treated + chemical conversion treatment with cerium 0.01 M can be ranked as follows according to their anticorrosive capacity: Ti6Al4V alloy <Ti6Al4V sample heat treated at 700 ° C <Ti6Al4V sample thermally + chemical conversion treatment treated with 0.01M cerium.
Passivation Magnesium in Phosphates for Its Application As Biomaterial
Authors: Ramírez Herrera José Manuel , Rodrígez Gómez Francisco Javier , Galicia Aguilar Gonzalo
Published: February 2020

Magnesium is potentially useful in biomaterial application. However, the corrosion rate of this metal is so high that its degradation occurs before the end of the healing process; for that reason, there are some researches for alloys as AZ31 and AZ91, as well as some treatments were applied to these alloys expecting a decreasing in the corrosion rate. The aim of this work is to decrease the corrosion rate and find a different material from the AZ alloys, for that reason we performed a chemical passivation of magnesium. We got this passivation through the immersion of the specimen in a phosphates solution. These passivations were evaluated with electrochemical techniques in Kokubo’s solution (SBF) and results were compared with not passivated magnesium and AZ31. Open circuit potential, EIS, polarization curves were carried out in order to evaluate passivation.

The material was chemically characterized by using atomic absorption, while the surface was analyzed before and after the techniques by Scanning Electron Microscope (SEM).

All experiments were realized at room temperature conditions (≈22°C=71.6°F); the surface of the probe was prepared with sandpaper: 240, 320, 400, 600, 1200, 1500 and finished with an alumina 0.3 m polish in order to ensure an homogeneous surface. The chemical treatment was performed at room temperature and by immersion, the samples remains in the solution for 24 hours.

Through the electrochemical techniques performed in this study, a decrease in corrosion rate was reported when the samples were passivated with the phosphates, this effect was observed in Fig. 1. This figure shows the polarization curve of magnesium, AZ31 and their passivation. The corrosion potential is different in each case, the Tafel slopes are also roughly different, these differences are important because it means that the corrosion rate was modified. This modification of the corrosion rate can be corroborated with Fig. 2 that shows a higher impedance in the case of passivation compared with the magnesium.
Evaluation of an Imidazoline in Simulated Atmospheric Conditions as Corrosion Inhibitor through Electrochemical Noise
Authors: Roncagliolo Barrera Paola , Flores-Álvarez José Fernando , Rodriguez-Gomez Francisco Javier
Published: February 2020

This work presents electrochemical noise measurement results from assessment of 2-methyl-2-imidazoline as inhibitor on a 1018 steel, at different relative humidity, categorized according to ASTM E 104 85.

A modified steel plates atmospheric corrosion probe (MECA) was used in order to measure potential and current noise time series; by using MECA, atmospheric corrosion rate could be determined, even if humidity was low.

Imidazoline is widely used in petrochemical industry as a corrosion inhibitor, so that was the reason for studying the behavior of this inhibitor in other corrosive processes as in the packaging or protection of metals exposed to atmosphere.

Spectral and statistical analysis of the noise data was carried out; after that, polarization curves were conducted to validate the information from noise and the use of MECA monitor. From the results, it was established that 2-methyl-2 imidazoline decreasing anodic potential and modifies the double layer adsorption.

The use of MECA monitor was validated, founding that records were reliable for electrochemical measurements of atmospheric corrosion.
Dissolution Mitigation of Alloy 690 By Electrochemical Surface Modification
Authors: Kim Kyung Mo , Shim Hee-Sang , Seo Myung Ji , Hur Do Haeng
Published: February 2020

Metal oxide particles and metal ions are released from the inside surface of steam generator (SG) tubes in operating nuclear power plants. These corrosion products are transported into the core, forming a crud on fuel cladding. The composition of the fuel crud consists mainly of nickel ferrite, and it indicates that the primary source is the nickel element in SG tube materials. A higher crud buildup might cause an increase in radiation dose rate and axial offset anomaly (AOA). The metal ion release property is affected by water chemical conditions, and metal surface states such as the roughness and residual stress (work hardening).

In this work, the metal surface modification technique for reducing the metal ion release is investigated using an electrochemical polishing method and is evaluated with micro hardening on the surface layer.

The corrosion tests were performed using commercial alloy 690, which was heat processed by two steps, mill annealed, and thermal treated. The electro-polishing (EP) process was applied by ElectoMet® 4 (Buehler Co, IL). The specimen used a tube shape of 19.05 mm outside diameter, and was electro-polished on the inside surface. After the EP process, the surface morphology and roughness was investigated by field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM).

The corrosion test environment simulated the primary water chemistry in PWRs. The temperature and pressure were maintained at 330oC and 150 bars during the experiments. The condition of the test solution was 2 ppm lithium (LiOH) and boron 1,200 ppm (H3BO4), 35 cc/kg (STP) dissolved hydrogen and 10 ppb dissolved oxygen.

The metal ion release rate was evaluated using a gravimetric analysis method using a two-step alkaline permanganate-ammonium citrate (AP/AC) descaling process.

The change in the surface morphologies of the corrosion products is not remarkable, while the release rate is lower by a factor of two when the surface was modified using the appropriate electrochemical polishing method. The metal ion release rate is mainly dependent on the surface roughness as the function of EP time and electrolyte composition. The specimen which had EP time for 8 minutes showed most improvement of metal ion release rate.