bluuebunny/crossref_metadata_2025 huggingface dataset:
Li1.2Zr1.9Sr0.1(PO4)3 as a Solid-State Electrolyte
Authors: Wolfenstine Jeff , Allen Jan L. , Sakamoto Jeff , Thompson Travis
Published: February 2020

In recent years there has been a resurgence in the use of Li metal as an anode, because such use can to lead to rechargeable batteries with higher energy than currently exist. Using a Li anode with a liquid electrolyte can lead to dendrite shorting and flammability issues. To overcome these problems Li-ion conducting solid electrolytes are attracting considerable attention. The major requirements for the solid Li-ion conducting electrolyte are: high Li-ion conductivity, low electronic conductivity, high relative density, chemical/electrochemical stability with the Li anode and cathodes, adequate mechanical properties. One possible electrolyte under consideration based on the NaSCION structure is Li1.2Zr1.9Sr0.1(PO4)3. It is the purpose of this presentation to discuss the following: 1] ionic/electronic conductivity 2] elastic modulus/hardness/fracture toughness and 3] Li /water stability of dense (~97%) fine-grain (~10 mm) Li1.2Zr1.9Sr0.1(PO4)3 consolidated by reactive hot-pressing. The results will compared to other Li-ion solid-state electrolyte conductors based on the NaSICON, perovskite and garnet structures.
Open and Academia: Datasets and Tools to Accelerate Electrochemical Science and Engineering
Authors: Schwartz D. T.
Published: February 2020

Electrochemistry has a strong scholarly legacy of bench-top scale “small” science. Over the past two decades, societal demand for improved electrochemical power sources—batteries and fuel cells—has driven a push for accelerating the process of turning a scientific discovery into a technology demonstration and, ultimately, an improved product. We discuss our lab’s effort to create valuable open source data sets and analysis tool. We are taking the most commonly used and cited full-physics lithium-ion battery model as the basis for generating a large library of impedance spectra that can be compared to experimental data. We have developed a data analysis and visualization tool to compare experiments and model in order to extract key physical parameters of the battery under test. We see open source datasets and analysis tools as complementary to the broader movement by ECS to Free the Science through open access.
Ionic Liquid Enhanced Polymer Elcetrolytes for Environmental Friendly Electric Double Layer Capacitors
Authors: Francis Katherine Anne , Liew Chiam wen , Ramesh K , Ramesh Subramaniam , Ramesh S
Published: February 2020

In this study we perform the preparation and characterization of poly (vinyl alcohol) (PVA)–added ionic liquid based ion conductors. The polymer electrolyte is incorporated with magnesium triflate [Mg(CF3SO3)2 or MgTf] as salt and 1–butyl–3–methylimidazolium bromide (BmImBr) as an environmental friendly ionic liquid. Differential scanning calorimetry (DSC) is carried out to investigate the glass transition temperature (Tg
), which is used to study the plasticizing effect of the ionic liquid. The polymer electrolyte with the lowest Tg
gives the highest ionic conductivity value of (1.64±0.01) x 10-3 S cm-1 at 60 wt.% of BmImBr. This is attributed to the plasticizing effect of the ionic liquid, which increases the flexibility of the polymer backbone, hence increasing the ionic mobility and segmental motion of the ions. The highest conducting ionic liquid based polymer electrolyte is used to fabricate electrical double layer capacitors (EDLC). The electrochemical potential window is evaluated using linear sweep voltammetry (LSV). Electrochemical capacitance of the EDLC is evaluated through cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD). The electrochemical potential window of ionic liquid–added polymer electrolyte is extended from 1.35 V to 2.6 V. Cyclic voltammetry (CV) proves the improvement in specific capacitance of the electrical double layer capacitors (EDLCs) containing ionic liquid–added polymer electrolyte by increasing the specific capacitance from 1.41 Fg-1 in the ionic liquid free polymer electrolyte to 45.95Fg-1 for the 60 wt% ionic liquid added polymer electrolyte.

Keywords:

Poly(vinyl alcohol); Ionic liquid; Mg(CF3SO3)2
, EDLC; Capacitance
Structure and Electrochemistry of Chromium Substituted Lithium Vanadyl Phosphate for Lithium-Ion Batteries
Authors: Lee Krystal , Siu Carrie , Chung Youngmin , Chernova Natasha A. , Omenya Fredrick , Whittingham M. Stanley , Lin Yuh-Chieh , Ong Shyue Ping
Published: February 2020

Lithium vanadyl phosphate (LiVOPO4) is an attractive cathode material for next-generation lithium ion batteries, having the ability to reversibly extract and insert two lithium ions to reach a theoretical capacity of 318 mAh/g. LiVOPO4 also has very high energy density over two voltage plateaus of about 2.5 and 4 V. However, the transition between the two voltage plateaus goes differently upon lithiation and delithiation, causing poor energy efficiency and cycling stability. Here we explore experimentally and by the first-principle calculations, if there is room to improve the efficiency and cyclability of this material with the use of chromium substitution. A series of lithium vanadyl phosphates with varying percentages of chromium from two different chromium sources, chromium oxide and chromium acetate, are synthesized by hydrothermal method. The structure and composition of the products are determined by x-ray diffraction and inductively coupled plasma atomic emission spectroscopy. The effect of chromium substitution on the reaction voltages is compared to the first-principle calculation results and the electrochemical performance as a function of chromium substitution is discussed. This research is supported as part of the NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0012583
Electrochemical and Chemical Stability of Solid Electrolyte–Electrode Interfaces: A First Principles Computation Study
Authors: Zhu Yizhou , He Xingfeng , Mo Yifei
Published: February 2020

All-solid-state Li-ion battery based on solid electrolyte materials is a promising next-generation energy storage technology. It can provide intrinsic safety, enable high-voltage electrode materials, and boost the achievable energy density. Currently, the key performance limiting factor of all-solid-state Li-ion battery is the high interfacial resistance and interfacial degradation at the solid electrolyte-electrode interfaces.

In this presentation, I will show how we use first principles computation to provide unique insights and fundamental mechanisms at these buried interfaces, which are difficult to access in experiments. We systematically investigated and compared the electrochemical stability and chemical stability of the solid electrolyte-electrode interfaces, and studied how these interfaces affect the battery performance, including interfacial resistance, long-term stability and cyclability.

Our computation results suggest the critical role of decomposition interphase layers at electrolyte-electrode interface and the significant effects of these interphase layers on the electrochemical performance of the all-solid-state Li-ion batteries. Different types of interfaces between solid electrolyte and electrode materials may have different problems at the interfaces, which require different interfacial engineering strategies to resolve. The mechanisms of artificial layers to improve the interfacial properties are also revealed by our computation. This computational study provides novel insights and general guidance for interfacial engineering in all-solid-state Li-ion batteries.
Electrochemical Discussion of Various Materials Modified By Friction Reforming Suitable for Marine Environment
Authors: Yao Zhu , Toshikazu Fujino , Tatsuhiro Jibiki
Published: February 2020

In recent years, since the ocean resources development has been emphasized, the importance of machines used in the marine environment seem to be growing. The sliding parts of equipment directly contact with seawater, so friction material with superior both corrosion resistance and wear resistance in marine environment is necessary. Thus, in order to develop friction materials adapted to marine environment, surface modification was conducted to add the properties of tribology and corrosion resistance to several materials. The method of surface modification is grouped into two major processing. One is the friction reforming process with powder and the other is zinc pin coating processing. Reforming layers are formed on the base material by this method. In past study, a lot of modified materials have been developed. To develop much more modified material, it is required that we efficiently find a better combination of base metal and powder to make the base material having the superior properties for wear and corrosion resistance. As the result of past study, we found that Ti+Cr2N and Ti+Al2O3 by friction reforming process had excellent wear resistance properties superior to these of base materials under seawater. On the other hand, it is difficult to clarify the corrosion resistance characteristics of the modifying material under seawater just by observation and the elemental analysis of the surface. In this paper, at first, the electrochemical measurement system was built to evaluate corrosion characteristics of the modified materials under seawater. Corrosion characteristics of modified materials can be obtained from measuring corrosion potential and the polarization curve. The corrosion potential and the polarization curve of austenitic stainless steel (JIS SUS304) and 0.45% carbon steel (JIS S45C) were measured to confirm reliability of the electrochemical measurement system. Then, since this system is a help for the understanding of the electrochemical phenomena during fretting test (reciprocating friction and wear test which amplitude is very small), the corrosion potential and the polarization curve of Ti-6Al-4V as a base material of Ti+Cr2N and Ti+Al2O3 by friction reforming process are measured under the 3.5%NaCl solution in static and dynamic conditions by using this system. The dynamic (fretting test) conditions is a normal load of 9.8N, a slip amplitude of 400μm, a frequency of 7Hz and total sliding distance of 16m (20000 cycles). In the polarization test, potential was scanned from -800mV to 600mV with a scan rate of 1mV/s versus the open circuit potential. Finally, the corrosion potential and the polarization curve of Ti+Cr2N and Ti+Al2O3 by friction reforming process are measured under the 3.5%NaCl solution in static and dynamic conditions and compared with these of Ti–6Al–4V. We discuss corrosion and wear characteristics of Ti+Cr2N and Ti+Al2O3 based on these results.
(Invited) Technology’s Role in Sustainable Energy
Authors: Williams Ellen D.
Published: February 2020

Extracting useful heat and work from energy sources is essential to human civilization, and the energy infrastructure that has developed to meet the world’s needs is immense, complex and weighted with legacy technology. Today issues of energy equity, environment, climate change and climate adaptation are transforming the context in which the energy system is evolving. Linkages to world-wide water, land and mineral use must be included in developing world’s future energy systems

Fortunately, the U.S. infrastructure of research and development has created a wealth of tools and approaches that allow new progress in providing energy efficiently, cleanly and sustainably.

The connectivity of energy with other resources will be reviewed, and examples of high-potential energy innovation will be presented, including highlights from the goal-oriented programs of the Advanced Research Projects Agency – Energy.
(Invited) Multimodal Microprobe for Combined Multiple Neurochemical Sensing and Optical Stimulation
Authors: Wassum Kate M , Chiou Pei-Yu , Maidment Nigel T , Monbouquette Harold G
Published: February 2020

Efforts to understand how neurons within networks interact to control behavior will be greatly facilitated by means with which to measure multiple neuroactive molecules in the brain simultaneously and in near-real time. We are developing an implantable microprobe capable of simultaneous rapid monitoring of three ubiquitous neurotransmitters/neuromodulators: dopamine (DA), glutamate (Glut), and acetylcholine. A detailed mathematical model is guiding electroenzymatic sensor optimization, and the use of a nanostructured Pt deposit has led to improved microsensors for choline and DA operated in constant potential amperometry mode. The creation of microsensor arrays for combined sensing of multiple neurochemicals is facilitated by the use of microcontact printing to deposit specific enzymes on selected microelectrode sites with fine control. Further, we are harnessing the power of optogenetics by incorporating an optical waveguide into our microprobes with microelectrode sensor arrays. This is achieved using an innovative silica-based microprobe design with embedded waveguides and a novel output grating coupler for directional illumination from the center of each neurochemical sensing site. The resultant microprobe enables local modulation of genetically isolated neuron terminals with measurement of transmitter release from those terminals. Our evaluation of probe performance in vivo has focused on the striatum and the basolateral amygdala (BLA). Optically evoked glutamate release has been observed successfully in the BLA of rats, but not in those genetically modified animals whose pre-synaptic activity is subjected to inhibition. Also, the improved DA sensors have enabled detection of electrical stimulation-evoked DA response in the rat dorsal striatum in the drug-naïve state. Further work to correlate multiple transmitter release events with behavioral actions will provide valuable information pertinent to the search for therapeutic interventions for multiple neurological and psychiatric disorders.
Three-Dimensional Freestanding Nanofiber Electrodes for Electric Double Layer and Pseudo-Capacitors
Authors: Kalra Vibha
Published: February 2020

Fabrication of novel three-dimensional material architectures is essential for development of energy storage devices that allow high rate operation with sufficient energy capacity. In this talk, I will present our work on development of freestanding nanofiber-based electrodes using a simple electrospinning methodology for application in supercapacitors (EDLC/Pseudocapacitors)

We have developed porous carbon nanofibers (PCNF) that exhibit specific surface area of >1500 m2/g and multi-levels of pore sizes in the range of micro (< 2 nm), meso (< 50 nm) and macropores (> 50 nm). We studied these materials as freestanding electrodes in 1) electric double layer capacitors (EDLC) using liquid (aqueous and ionic liquid), as well as solid-state electrolytes and 2) as platforms for polyanilene (PANi) electrodeposition to develop hybrid supercapacitors that integrate electric double layer and pseudocapacitive energy storage. The unique combination of pores at different length scales allows us to achieve a battery-like energy density of up to 80 Wh/kg, while retaining high power and cycle life in EDLCs. In-operando infrared spectroelectrochemistry was conducted to understand the transport of ions through the carbon electrode pores and its effect on performance in ionic liquid-based EDLCs. In the hybrid supercapacitor devices, we demonstrated that the PCNF mats retain their EDLC behavior post PANi coating providing a 366 F g–1 gravimetric capacitance, 140 F cm–3 volumetric capacitance, and up to 2.3 F cm–2 areal capacitance at 100 mV s-1scan rate based on the weight, volume and area of the complete hybrid electrode – polyaniline coating and carbon substrate.

Relevant References: 1) Tran, C.; Lawrence, D.; Richey, F.W.; Dillard, C.; Elabd, Y.; Kalra, V. Electrochemical Performance of Device-ready Porous Carbon Nanofibers in Ionic Liquid Electrolyte-based Supercapacitors. Chemical Communications 2015, 51, 13760; 2) Richey, F.W., Tran, C., Kalra, V., Elabd, Y.A. Ionic Liquid Dynamics in Nanoporous Carbon Nanofibers in Supercapacitors Measured with in operando Infrared Spectroelectrochemistry, The Journal of Physical Chemistry C, 2014, 118, 21846; 3) Tran, C.; Singhal, R.; Lawrence, D.; Kalra, V. Polyaniline-coated Freestanding Porous Carbon Nanofibers as Efficient Hybrid Electrodes for Supercapacitors. Journal of Power Sources 2015, 293, 373.
Electrochemical Characterization of Dispersions Containing Lithium-Ion Battery Active Materials
Authors: Koenig Gary , Qi Zhaoxiang , Gupta Devanshi
Published: February 2020

This talk will introduce probing the electrochemical properties of dispersions of lithium-ion battery active material particles, and discuss how such characterization can provide insights into the use of these particles both in flow battery systems and in conventional static lithium-ion battery electrodes. The characterization of materials appropriate for both anode and cathode materials for lithium-ion batteries will be presented, and the necessary considerations and modifications for characterizing materials within these different electrochemical potential ranges will be discussed. An advantage to using flowing suspensions to electrochemically probe battery active materials are that 1) the impact of other cell materials can be omitted (other composite electrode, binder, conductive additive, etc.), 2) the electrode microstructure should not significantly influence measurements, and 3) the analysis is relatively fast for probing a battery active material sample across a variety of currents or potentials.
Design and Construction of Novel High-Performance Li-Ion Hybrid Supercapacitors Based on 3D Graphene Composites
Authors: Liu Wenwen , Han Lei , Tjandra Ricky , Lui Gregory , Feng Kun , Yu Aiping
Published: February 2020

Li-ion hybrid capacitors (LIHCs) as a novel and promising energy storage unit, consisting of a Li-ion battery type anode and an electrochemical double layer capacitance (EDLC) type cathode, has attracted enormous research attentions. However, it remains a significant challenge to obtain high-performance LIHCs due to most battery-type anodes with the sluggish kinetics of Li-ion storage and low specific capacitance of common capacitor-type cathodes. Thus, it is highly required to design and fabricate novel alternative high-performance battery type anode materials and capacitor-type cathode materials, able to deliver higher energies and power densities in organic electrolyte. In this work, a novel high-performance LIHCs is constructed by combining a Li-ion battery type anode (3D graphene/MoO3 nanocomposite) with a capacitor type cathode (3D graphene/PANI derived carbon material). Such a subtle design endow LIHCs with a wide voltage range of (3.8 V), a high energy density of 128.3 Wh·kg-1, and an ultra-long cycle life up to 3000 cycles with 87% capacity retention.
Melamine-Based, N-Doped Carbon/Reduced Graphene Composite Foam for Li-Ion Batteries and Hybrid Supercapacitors
Authors: Tjandra Ricky , Liu Wenwen , Liu Yangshuai , Yan Ji , Lim Lucas , Yu Aiping
Published: February 2020

Carbon foams, especially graphene foams, has recently received a lot of interest in the field of flexible energy storage due to their excellent electrochemical properties and flexibility. In this work, a compressible melamine-based carbon/reduced graphene oxide foam was synthesized using a simple one-step process. The nitrogen-rich melamine allows the final composite material to be rich in nitrogen, resulting in a higher conductivity and performance. The synergistic combination of nitrogen-doped carbon foam and reduced graphene oxide results in a compressible, free-standing, binder-free electrode (shown in Figure 1) with a capacity of 330 mAh g-1 at 0.1 A that can be used in both Lithium-ion Hybrid Supercapacitors (LIHSs) and Lithium-ion Batteries (LIBs). The composite electrode can also be used as a current collector for other active materials. As a proof of concept, a LIHS was fabricated using the composite foam as a free-standing electrode in both the cathode an anode. The resulting device has an energy density of 40 Wh kg-1 at 1 A that can be maintained for 800 charge and discharge cycles.

Figure 1 (a) 3D representation of the cMEGX synthesis procedure, (b) SEM image of neat melamine, (c) SEM image of a representative cMEGX sample, (d) optical image of cMEG800 showing its compressibility 

Figure 1
3D-Carbon Hybrid Nanostructure Formation Using Zeolite Template
Authors: Rojas Carolina Valeria , Santa Cruz Neida
Published: February 2020

The emerging carbon-based materials possess properties that depend on the way how carbon is structured at the nanoscale. Synthesis of novel three dimensional (3D) nanostructures of carbon compound would be an important advance for fundamental research and various applications. In this work, we discuss the possibility of fabricating complex 3D nanostructures by growing carbon-compounds on pre-synthesized nanostructured zeolites templates by chemical vapor deposition (CVD) and then etching away the zeolites. We study two types of zeolites structures, NaX and NaY. We systematically study the roles of different parameters, such as the composition, morphology and crystallinity of the material on zeolites-template, as well as the CVD growth temperature and different carbon sources to synthesize the carbon-compound on zeolites. The same time we will shows that polycrystalline nanostructures start to growth at low temperature of 500 oC. However we observed that the crystallinity of the nanostructures was affected by the selection of reactive carbon source that is deposited on the zeolite from lower temperatures. Furthermore, the selection of a zeolite is also important, as type X are shown to be more resistant to thermal damage than their type Y. We could successfully remove the zeolite templates to form free-standing carbon-based hollow nanostructures. This 3D structure could be used in water or air filters in a potential biological application for removal of bacteria in conditioner airs or and plants of water treatments. The results presented in this analysis could to help the synthesis of other 3D-carbon nanostructures
Carbon Nanotubes Modified with Fluorine
Authors: Zeferino González Isaias , Demers Hendrix , Brodusch Nicolas , Gauvin Raynald , Valenzuela-Muñiz Ana Maria , Verde Gómez Ysmael
Published: February 2020

One of the most remarkable properties of carbon is the ability of its atoms to combine with other elements allowing a great diversity of nanostructures, e.g., carbon nanotubes (CNTs). The unique properties of these materials, such as good electrical conductivity, chemical stability, light weight, and ease of handling make them suitable materials for electrochemical applications. Recently, the insertion of heteroatoms in the carbon structure have been used in order to modify and enhance the CNTs physical and chemical properties. The present study shows the synthesis and characterization of carbon nanotubes modified with fluorine (CNTs/F). The materials were synthesized by a modified chemical vapor deposition using toluene as carbon source and ferrocene as metal catalyst for the nanotubes growth. Fluorobenzene was used as a precursor of fluorine. During the process, parameters such as synthesis temperature (900°C - 1000°C) and fluorobenzene concentration in the toluene solution (20 - 80 g/L) were varied. The effects of these factors were investigated using high-resolution scanning electron microscopy and x-ray microanalysis by energy dispersive spectroscopy (SEM-EDS), transmission electron microscopy (TEM), x-ray diffraction (XRD), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS). The results showed that the morphological and physical properties of CNTs/F, such as wall thickness and defects changed in comparison to those of pristine CNTs. According to the Raman spectroscopy results, the composite materials showed major defects in the structure. These changes can be explained by the integration of the fluorine atoms in the structure of the nanotubes, which increase the disorder of the graphitic network. Morphology, elemental composition and chemical state of the carbon-fluorine bonds will be discussed as well as their effects in the electrochemical applications in lithium-ion batteries.
Non Destructive Evaluation of Urethane-Epoxy Coating Systems Using the Scanning Kelvin Probe Technique
Authors: Borth David , Hansen Douglas C
Published: February 2020

High performance aircraft are subjected to harsh environmental factors during operation including impacts with water and other particles, as well as high temperature and humidity. Rain erosion coatings (REC), made from polyurethane (PU), are used to protect the metal and other coatings from these damaging elements by absorbing the force of impacts and providing a barrier against corrosive substances. Over time these coatings break down and may fail in flight by delamination. Failure of a coating leads to unplanned downtime and expensive refinishing procedures. Coatings that are exposed to high temperature and humidity are particularly susceptible to degradation, leading to the assumption that the cause is hydrolysis or reversion. Hydrolysis affects the esters linkages whereas reversion targets the urethane bonds. These types of degradation lead to a breakdown of the polymer network structure and reduce both the tensile strength and melting point of the coating, increasing the likelihood of failure.

The dynamic nature of weather makes predicting when the PU REC will fail is extremely difficult when using traditional lifecycle estimates, since aircraft are exposed to different environmental conditions at different geographical locations or areas of operations. Currently, no method exists for accurately predicting when a particular aircrafts coating will fail. Therefore, there is a need for a reliable non-destructive method to detect the changes in the surface coating that indicate when it is close to failure or has begun to fail.

It is hypothesized that the Scanning Kelvin Probe (SKP) can be used to detect changes in the work function of the REC’s associated with degradation of the polymer structure. If successful, it will serve as the justification for developing a portable scanning unit that can be deployed by maintenance crews to determine when a coating needs to be reapplied. To test this, 4X6 inch 2024 aluminum alloy test panels were exposed in an autoclave to high heat and humidity (121˚C and 100% RH) for a variety of times to simulate the degradation process. They were then scanned with the SKP to characterize the degradation as a function of exposure time. Initial data shows that there is a change in work function with increasing exposure as well as localized areas of higher work function. Raman spectroscopic analysis indicates changes in coating polymer chemistry consistent with hydrolysis of the ester bonds. This data correlates with the changes in work function seen by the Kelvin probe, showing that the SKP can non-destructively detect polymer degradation.
Electrochemical and Corrosion Protection Performance of New Polymer Composite Coatings on Carbon Steel in Sulfuric Acid Medium
Authors: Branzoi Florina , Pahom Zoia
Published: February 2020

In this study, galvanostatic electrodeposition mode was used for the synthesis of new composite (Ppy-AOT/PNEA and PNEA/ Ppy-AOT) coatings onto carbon steel of type OLC 45 for corrosion protection.

Monolayer poly (N- ethylaniline) (PNEA), polypyrrole (Ppy), dioctyl sulfosuccinate sodium (AOT) and bilayer PNEA/Ppy-AOT and Ppy-AOT/PNEA coatings have been electropolymerization onto carbon steel by galvanostatic synthesis techniques from aqueous solutions 0.1 M N ethylaniline, 0.1M pyrrole, 0.01 M dioctyl sulfosuccinate sodium (AOT) and 0.3 M oxalic acid. In order to include dioctyl sulfosuccinate ions as dopant in the polypyrrole, AOT was also added to the polymerization solution of polypyrrole.

The monolayer and bilayer polymers coatings were characterized electrochemically, spectroscopically and morphologically by cyclic voltammetry, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) techniques.

Corros ion behaviour of PNEA-AOT/PPY coated carbon steel of type OLC 45 was investigated by potentiostatic and potentiodynamic polarization, open circuit potential measurements and electrochemical impedance spectroscopy (EIS) techniques in 0.5M and 1 M H2SO4solutions. The results of the corrosion tests showed that PNEA/PPY-AOT coatings ensure good corrosion protection of carbon steel in aggressive media. Bilayer coatings revealed better corrosion protection efficiencies than monolayer coatings. The new complex nanostructured composite obtained from this process is promising and might lead to industrial applications in the protection of the carbon steel substrates against corrosion.

 

Keywords: nanocomposite films, galvanostatic electrodeposition, corrosion protection, SEM, EIS, FT-IR
Artificial Pits for the Study of Underdeposit Corrosion Kinetics
Authors: Shamso Ahmed Nabil , Abdullah Aboubakr Moustafa , Laycock Nick , Ryan Mary P
Published: February 2020

The extraction of oil and gas from relatively abundant sour fields was triggered by the continuous growing need for fossil fuels. Sour (H2S –containing) gas environments present a major problem of underdeposit corrosion (UDC) which is a type of accelerated localized corrosion observed under deposits (in this case typically iron-sulfides), creating a risk to asset integrity. The mechanism of UDC is still not fully understood and there is no consensus on the methods used to evaluate UDC in pipelines. In addition, the efficacy of inhibitors may vary in such a scenario and so the amounts and efficiencies required cannot be a priori decided. There is, therefore, an urgent need for a study that addresses the characteristics of deposits representative to the different conditions present in the real environment, and the use of such a protocol to provide kinetic and mechanistic information on UDC phenomena. 1-dimensional artificial pit experiments were performed where the artificial pit acts as an anode in a three-electrode electrochemical cell, simulating an actively dissolving pit. The dissolution kinetics were obtained as a function of system variables such as chloride concentration, pH and existence of deposit at the pit cavity opening. Data will be presented on the role of deposit chemistry and morphology on the electrochemical dissolution behaviour and discussed in terms of a transport-controlled model for pit propagation.

Keywords: Pitting corrosion; artificial pits; underdeposit corrosion; sour gas
Effect of Residual Chlorine Concentration on Water Pipe Corrosion
Authors: Han Keum Seok , Park Ju-hyun , Park Young-bog , Kim Seong Jea , Kim Hyen Don , Choi Young-june , Choi In-cheol , Hong Seong Ho
Published: February 2020

1. Introduction

Water pipe corrosion corrodes the iron by the oxidation reduction reaction, and the corrosion rate is accelerated by the oxidizing agent used as disinfectant in the tap water. The major oxidizing agent in tap water are ozone and chlorine. pH, alkalinity and residual chlorine concentration are factors of internal corrosion.

We are replacing the ductile cast iron pipe with inner coating and stainless steel pipe. However, it is still used in many cases, such as gray cast iron pipes and galvanized steel pipes without internal coatings in Korea.

Chlorine is a very strong oxidant for all metals and organics, and the reaction between chlorine and iron is as follows.

HOCl + 2Fe2+ + 5H2O → 2Fe(OH)3↓ + Cl- + 5H+

Recently, as the problem with sinkholes has arisen on the a buried road as water pipes, sewage pipes, etc, interest in corrosion has been growing.

The purpose of this study is to evaluate the effect of residual chlorine on the corrosion factor by analyzing the water quality and to evaluate the necessity of the proper residual chlorine on in the water purification plant.

2. Experimental Method

In order to evaluate the corrosion of residual chlorine concentration of tap water, we were carried out Tafel experiment and water quality analysis. The corrosion rate was measured by a Tafel experiment using an electrochemical corrosion measurement system (PAR VMP-3). For tap water in Seoul, corrosion evaluation was performed according to alkalinity and hardness, residual chlorine concentraion.

3. Summary of results

The tap water quality of Seoul was as follows that residual chlorine is 0.4 mg/L, and alkalinity is 50 mg/L as CaCO3, with a pH of 7.3. The results of experiments on the rate of corrosion of Carbon Steel specimens to residual chlorine in seoul tap water, can be seen in Fig. 1.

As a result of the Tafel experiment according to the initial residual chlorine concentration under the same conditions (same LI index), The corrosion rate was 0.01 mmpy at 0 mg/L of residual chlorine and 0.074mmpy at 0.8mg/L of residual chlorine, corrosion rate for residual chlorine in carbon steel specimens was more than 7 times. It was confirmed that the higher the concentration of residual chlorine, the faster the corrosion rate was increased.

The corrosivity of tap water in Korea is evaluated by the LI index, but residual chlorine has a large effect on corrosion, so it is required to add residual chlorine for the tap water corrosion evaluation.

It is reducing the concentration of residual chlorine for reduce the chlorine odor of tap water in the distribution water system in Korea. But, residual chlorine guideline for corrosion reduction is necessary in Korea.

Figure 1
Examining the GaN Photocorrosion Potential for Stable Chemical Energy Storage
Authors: Baker David R
Published: February 2020

Some of the most promising materials for photoelectrochemical water splitting are III-V semiconductors due to their high photoelectrochemical efficiency, and their inherent band positions with respect to the water splitting reactions. However, one of the primary detractors from their widespread use is their short lifetimes due to photocorrosion. GaN is an example of this as it readily photcorrodes in both acidic and basic aqueous media, though in dark environments it is stable. An electrochemical understanding of the corrosion reaction is imperative, but the traditional potentiodynamic analysis to determine corrosion potentials is impaired by the masking of photogenerated holes by the photocurrent of the solar cell. This talk presents how Mott-Schottky analysis can alternatively be used to find the photocorrosion potential of GaN, and how it relates to previously calculated surface properties of c-plane GaN. Using the newly found photocorrosion potential and mechanism several passivation methods, such as ALD and hole scavenging, are investigated to minimize the corrosion mechanism. Additional characterization techniques such as AFM and SEM are used to probe the corrosion mechanism and observe the effectiveness of passivation methods. The information found from this analysis will allow new materials to be designed which are inherently resistant to photocorrosion without the need for expensive and intensive surface passivation modifications.
Atmospheric Corrosion of 904L Austenitic Stainless Steel at Different Environments
Authors: Abdullah Aboubakr Moustafa , Sliem Mostafa H , Mohamed Adel M
Published: February 2020

A major concern for metals and alloys in structural applications is susceptibility to atmospheric corrosion. The atmospheric corrosion behavior of 5 mm-thick 904L austenitic stainless steel (904L SS) coupons of dimensions 10 x 10 cm2 was studied as a part of a ﬁeld exposure program for many alloys under a variety of environmental conditions that are existing in Qatar. Seven locations (stations) were selected to participate in this study representing desert, marine, coastal and industrial areas in Qatar. The study was implemented using image analyzer, scanning electron microscope (SEM) coupled with energy dispersive x-ray (EDAX) and electrochemical characterization techniques. The number of pits and pits’ depths and aspect ratios were calculated. Moreover, the thickness of oxide layer was detected using x-ray photoelectron spectroscopy (XPS). The analysis of the collected coupons revealed the corrosion behavior of 904L SS specimens and fasteners in various exposure conditions after different times of exposure. In addition, a correlation was made between the effects of various environmental conditions e.g. Cl-, and SO2 concentration in air and the extent and forms of corrosion. In general, 904L SS alloy formed several pits in the crevice regions and some pits also appeared on its flat surface, especially at marine and coastal industrial sites. Test coupons at desert test station didn’t form any corrosion products on its surface or around the crevice areas. It is clear that the number, the size and the aspect ratios of pits depend on the aggressiveness of the site’s environment. The pits’ density and aspect ratio were found to follow the following order; North field > Ras Laffan > Seaside Mesaieed > Industrial Mesaieed > Halul > Dukhan > Desert.

Figure 1
A Study of NiTi Alloy Mechanical and Corrosion Behavior Subjected to Mechanical and Cyclic Thermal Loading in Corrosive Environment
Authors: Mohajeri Mahdi , Castaneda Homero , Lagoudas Dimitris
Published: February 2020

The corrosion behavior of a nickel titanium alloy (NiTi) have been investigated. The NiTi alloy is

subjected to cyclic thermal loading in corrosive environments (3.5 wt% NaCl and Ringer

solution).

Thermogravimetric measurement versus temperature is perfumed to obtain forward and

reverse martensitic transformation temperatures.

Electrochemical Avesta cell is used to study corrosion behavior of NiTi alloy under thermal

cycling in absence of mechanical loading. Electrochemical Impedance Spectroscopy and cyclic

voltammetry measurements are used to study corrosion behavior at different temperatures

and phases.

The change in corrosion rate during phase transformations are being investigated. An

equivalent circuit model is used to calculate the electrochemical parameters from EIS

measurements for forward and reverse martensitic transformations. The results shows the

breakdown of passive oxide film on the surface with martensitic transformation. This

breakdown would be an origin for fatigue crack initiation and an explanation for fatigue lifetime

reduction of NiTi in corrosive environments.
Galvanic Corrosion of AA7075-T6 Caused By Doped Titanium Oxides in a Controlled Atmospheric Environment
Authors: Policastro Steve , Anderson Rachel , Horton Derek J. , Hangarter Carlos , Keith John A. , Groenenboom Mitchell C.
Published: February 2020

Reduction reactions, such as oxygen reduction, hydrogen evolution, nitrate reduction, and sulfate reduction, are of interest in atmospheric corrosion because they are more positive than many structural airframe alloy oxidation reactions and can therefore drive material breakdown. The rate controlling reduction reaction is the one capable of supporting the largest corrosion rate at a given potential. In the case of heterogeneous corrosion, in which the anodic and cathodic sites are spatially distinct and stable, as is found in a galvanic couple; the ability of the noble metal to support a reduction reaction strongly influences the corrosion of the active metal.

For aircraft alloys having received conversion coatings and topcoats to control self-corrosion due to precipitate phases, high-strength fasteners made of stainless steel or titanium alloys are the most obvious point of attack for galvanic corrosion. In atmospheric electrolytes, droplet chloride concentrations can exceed 4M, and the oxygen reduction reaction (ORR) is frequently the dominant reduction reaction driving corrosion. Novel binary titanium alloys that had been developed using density functional theory and Monte Carlo simulations that predicted oxygen reduction reaction (ORR) rates on the metal oxides, were coupled to structural aluminum alloy (AA7075-T6) panels and exposed to a simulated tropical rainforest environment for 30 days in order to compare predicted galvanic corrosion rates with actual galvanic corrosion in an environment in which Cl-ions were applied in a controlled manner.

Acknowledgment

This work was sponsored by the Office of Naval Research, ONR, under grant/contract number N0001415WX00948; the views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Office of Naval Research, the U.S. Navy or the U.S. government.

Figure 1. Galvanic corrosion test panels exposed to a simulated tropical rainforest environment with controlled chloride dosing.

Figure 1
Dissolution and the Consequent Surface Morphology of Pt-Cu Binary Alloys Under Potential Cycling
Authors: Ooi Azusa , Tada Eiji , Nishikata Atsushi
Published: February 2020

Polymer electrolyte fuel cell (PEFC) is regarded as clean energy conversion system, however its high cost prohibits the progress of PEFC. Thus, a reduction in the amount of Pt used as cathode catalyst is required. In order to overcome this problem, Pt transition-metal (Pt-M) alloy catalysts have been developed instead of Pt catalysts, however a deterioration of Pt-M alloy catalysts is concerned because both Pt and M are dissolved from Pt-M alloy catalysts under PEFC operating conditions. In this study, potential cycling tests and inductively coupled plasma mass spectroscopy (ICP-MS), field emission-scanning electron microscopy (FE-SEM), and field emission auger electron spectroscopy (FE-AES) were combined, and dissolution behavior of Pt-Cu alloys has been investigated under potential cycling by using these techniques.

Pt50-Cu50 (Pt-50 at% Cu) and Pt25-Cu75 were fabricated by arc-melting under an Ar atmosphere. These alloys were subjected to potential cycling tests at 298 K in 0.5 M H2SO4 solution with a two-compartment stationary cell. A double junction silver / silver-chloride electrode was used as reference electrode, and Au coil was used as the counter electrode. A total of 1,000 cycles of potential cycling tests were employed between 0.05 V and 1.4 V vs. SHE at 100 mV s-1. Tests was interrupted every 100 cycles, and the test solution was sampled for quantitative ICP-MS analysis of both Pt and Cu ions dissolved in it. In addition, surface structure and depth profile after potential cycling tests were evaluated by FE-SEM and FE-AES, respectively.

FE-AES depth profiles before and after 100 cycle potential cycling confirmed that Pt-enriched layer formed on Pt25-Cu75 surface after potential cycling. Moreover, the amount of dissolved Pt and Cu ions during 1st sequential order of 100-cycles-potential cycling were 1 monolayer (ML) and 2370 ML, respectively. Hence, Pt-enriched layer formed by the large amount of Cu selectively dissolved from Pt25-Cu75. FE-SEM image of Pt25-Cu75 after 100 cycle potential cycling showed numerous pits (d
pit = 2 – 5 nm) formed on its surface, and the large amount of Cu dissolution occurs from 2nd to 10th sequential order of 100-cycles-potential cycling. Thus, selective dissolution of Cu seems not to be suppressed in the latter cycles because Cu dissolution continuously occurs through the pits. On the other hand, FE-SEM image of Pt50-Cu50 after 100 cycle potential cycling was extremely flat. Accordingly, dense Pt-enriched layer formed on its surface, and it suppressed further Cu dissolution from the alloy.

The authors acknowledge Ookayama Materials Analysis Division, Tokyo Institute of Technology, for assistance with the ICP-MS analysis.
Regenerative Electroless Etching of Silicon
Authors: Kolasinski Kurt W , Gimbar Nathan J. , Yu Haibo , Aindow Mark , Mäkilä Ermei , Salonen Jarno
Published: February 2020

We introduce regenerative electroless etching (ReEtching). This is a method of producing nanostructured semiconductors in which an oxidant (Ox1) is used as a catalytic agent to facilitate an etching reaction between a semiconductor and a second oxidant (Ox2) that would be unreactive in the primary reaction. Ox2 is used to regenerate Ox1, which is capable of initiating etching by injecting holes into the semiconductor valence band. Thereby the extent of reaction is controlled by the amount of Ox2 added and the rate of reaction is controlled by the injection rate of Ox2. This general strategy is demonstrated specifically for the production of highly luminescent, nanocrystalline porous Si from the reaction of V2O5 in HF(aq) as Ox1 and H2O2(aq) as Ox2 with Si. The Si can be in the form of wafer, high-purity powder, metallurgical grade powder, or porous Si powder made by pulverization of an anodized wafer. ReEtching of metallurgical grade powder represents an inexpensive method of producing porous silicon powders that is scalable to large quantities for use in applications such as batteries and drug delivery. Depending on the etching conditions, the powder particles may be etched completely through (complete porosification), or be comprised of a porous layer surrounding a solid core. Pillared silicon particles can also be produced. Mesoporous Si that was nonluminescent after formation by anodization can be ReEtched to produce brilliantly photoluminescent powder with extremely high specific surface area. PL bands from blue to red have been observed. PL in the red to near IR is extremely long lived, exhibiting multi-exponential decay with lifetime components in excess of 100 µs. Biological tissue autofluorescence exhibits lifetimes in the nanosecond range. Thus, the long-lived PL from Si nanoparticles is promising for bioimaging applications in which image acquisition is delayed after the initial photoexcitation.