Name: potentiodynamic corrosion testing
Uploaded: 2016-09-04T14:00:00.000+00:00
Duration: 8 min 43 s
Description: Watch this Scientific Journal Video about Potentiodynamic Corrosion Testing at JoVE.com

The authors had no funding provided for this study.

1. Construcción del titular de la Muestra <ol><li> Construir el portamuestras y separadores de acero inoxidable y un tornillo de acero inoxidable roscado M3, que se celebró en su lugar con una tuerca hexagonal M3. </li><li> Retire la cabeza del tornillo roscado con unos alicates y pulir el segmento de corte para mantener el patrón de rosca. </li><li> Cuando todos los componentes individuales están listas, montar las pinzas de soldadura. Cada soporte del electrodo contiene tres espaciadores unidos entre sí mediante los tornillos M3 que resulta en un mango de 11,5 cm. Colocar las tuercas hexagonales en la unión del tornillo y espaciadores para bloquear la conexión. </li><li> Solder (60/40% Sn / Pb) una pinza de cocodrilo sin dientes en el tornillo en el extremo de la varilla. Esto asegurará un agarre firme para unir más tarde el electrodo durante el análisis. </li><li> Una vez que los soportes de electrodos se montan, aplicar varias capas de laca de parada (sellador eléctrico) para evitar que las varillas de acero inoxidable de la corrosión mientras se sumerge en la cámara de corrosión. <ol><li> Coloque todos los titulares de los electrodos con las muestras unidas a la pinza en una campana de humos antes del recubrimiento. Coloque una jeringa de 20 ml en la campana de humos. Utilice la jeringa para recoger la laca de parada. </li><li> Encienda la campana de humos y verter el barniz de parada en un pequeño frasco de vidrio. Tire 10 ml de laca de parada en la jeringa y recubrir la superficie de los soportes de electrodos. Asegúrese de no cubrir la muestra de ensayo, que se va a analizar en busca de corrosión. </li><li> Escudo mitad de cada soporte del electrodo y colocar en la campana de humos se seque antes de aplicar la otra mitad. Esto ayudará a obtener una capa bien sellado completo sin dañar las áreas a recubrir. Asegúrese de que durante la fase de secado, las regiones recién recubierto, que no toquen otras superficies, ya que esto va a arruinar la capa aplicada. </li><li> Coloque los soportes de electrodos en una posición elevada durante el secado sin contacto con ninguna superficie. Recubrir los electrodos rápidamente debido a la solidificación rápida de la laca de parada.Esto completa la primera capa. </li><li> Una vez seco, repetir el proceso para obtener 3 capas a lo largo de toda la zona. </li></ol></li><li> Antes de comenzar la sesión a la corrosión, deje los titulares de secar durante 24 horas después de la finalización de la última capa. Todos los procesos de recubrimiento se producen a temperatura ambiente, no se requieren etapas de calentamiento o de enfriamiento aunque pueden acelerar / decelerar el proceso de curado. </li><li> Realización de una jaula de Faraday <ol><li> Construir una jaula de Faraday mediante el recubrimiento de dos recipientes de plástico del mismo tamaño con 4 capas de papel de aluminio para cubrir todos los lados. </li><li> Cortar dos agujeros pequeños a cabo en el borde del recipiente de plástico superior para permitir la conexión del electrodo al potenciostato y la línea de nitrógeno al tanque de nitrógeno para pasar a través. Un diseño de la fractura de la jaula de Faraday permite que el componente superior para ser retirado al final de una carrera sin la necesidad de reemplazar la sección de la carcasa inferior del tanque. </li><li> Montar el compartimento externo (cámara de agua) en la jaula de Faraday. leave la segunda mitad de la cara y el lugar en la parte superior del compartimiento inferior sólo cuando la vasija de corrosión se ha sellado (más adelante en el procedimiento). </li></ol></li></ol> 2. Limpieza de cristalería <ol><li> Limpiar la vasija de corrosión (vaso cilíndrico 700 ml) antes de cada proceso de corrosión. Frote el recipiente con detergente y enjuagar bien con agua del grifo. Repita este paso 3 veces. </li><li> Enjuagar el recipiente de la corrosión 3 veces con agua desionizada (DI) para eliminar los contaminantes potenciales que se encuentran en el agua del grifo. </li><li> Una vez aclarado con agua DI se completa verter 300 ml de 95% de etanol en el recipiente de la corrosión y de remolino alrededor de ponerse en contacto con todas las superficies internas. Vierta el etanol y repetir este paso 3 veces. </li><li> Deje la vasija de corrosión bajo una campana de humos durante 30 minutos para permitir que todo el etanol se evapore por completo. </li><li> Tome la vasija de corrosión limpia, seca y enjuagarlo con el electrolito que se utilizará para la ejecución de la corrosión. DelanteroACH enjuague llenar la vasija de corrosión con 200 ml de electrolito y repetir este procedimiento 3 veces. Para este estudio, enjuagar el recipiente de la corrosión con solución salina tamponada con fosfato (PBS). La composición química de la (10 L) de electrólito utilizado a través de PBS es 80 g de NaCl, 11,5 g de Na 2 HPO 4, 2 g de KCl y 2 g KHPO 4. </li><li> Tras el enjuague, llenar el recipiente de la corrosión con el volumen requerido de PBS listo para la reacción. </li></ol> 3. Configuración del Aparato <ol><li> Abrazadera de un calentador con un sistema de circulación incorporado para el lado del compartimento exterior mediante una abrazadera. El tamaño del compartimento externo tiene que ser de aproximadamente 30 cm x 20 cm x 20 cm y está hecho de vidrio o polimérico que es capaz de alojar la vasija de corrosión más pequeño y el sistema calentador. </li><li> Llenar el compartimento exterior con agua del grifo hasta que el nivel de agua es mayor que la altura de los electrodos en suspensión dentro de la vasija de corrosión. El compartimiento más pequeñoes la vasija de corrosión (anteriormente descrito en la sección 2). </li><li> Sellar el recipiente de la corrosión con una tapa de reacción de vidrio y la abrazadera para asegurar un sello impermeable. La tapa de la cámara proporciona seis puntos de entrada para un aparato experimental y medición. </li><li> Suspender un termómetro de uno de los puntos de entrada de la tapa de reacción para proporcionar una lectura de la temperatura dentro de la célula de corrosión. Suspender los tres electrodos de la tapa utilizando los otros 3 puntos de entrada. Utilice politetrafluoroetileno cinta (PTFE) para asegurar el sello de cada conexión. </li><li> Usar una configuración de tres electrodos que consiste en una referencia, contador, y el electrodo de trabajo. El electrodo de trabajo es el tornillo de acero inoxidable (muestra bajo análisis). Antes de insertar el electrodo en la vasija de corrosión, limpie con una mezcla de etanol del 80% empapado limpiar y colocar en un vaso de vidrio lleno con 100 ml de PBS. </li><li> Use un pasador de conexión para fijar los soportes de electrodos en los tirantes de los electrodos. Montar el electrode tirantes en los puntos de entrada de la tapa de la vasija de corrosión. </li><li> Coloque el electrodo de trabajo en el centro con el contraelectrodo y la referencia que se suspende desde cualquier lado. Sellar el punto de entrada de vidrio y los tirantes de corrosión utilizando cinta de PTFE. </li><li> Para el electrodo de referencia, utilizar un estándar Ag / AgCl. Para el contraelectrodo, el uso de una malla de platino que era ligeramente doblada para envolver alrededor de la muestra bajo prueba (electrodo de trabajo). </li><li> Llenar el electrodo de Ag / AgCl con 3 M KCl con una pipeta. Después de un uso prolongado, el cambio y volver a llenar el Ag Ag / Cl. Para ello soltar la punta del electrodo para vaciar el líquido en un recipiente de recogida vaso pequeño (vaso de precipitados). Una vez que toda la solución se retira introduzca la punta y se llenan de 3 M KCl. </li><li> Use cinta adhesiva en todas las uniones para asegurar toda la cámara está sellada. </li><li> Una vez que la cámara está sellada con todos los electrodos colocados en el interior del recipiente de la corrosión, ajustar la temperatura a 37 ° C y abra la válvula de nitrógeno ingenioja velocidad de 150 cm3 / min de caudal. Deja la temperatura y nitrógeno en funcionamiento durante 60 minutos antes de la realización de una carrera. Seguir corriendo nitrógeno durante la duración del experimento. </li></ol> 4. Ejecución de Prueba de corrosión <ol><li> Abra el paquete de software electroquímico, que interconecta con el potenciostato controlado USB. </li><li> Haga las conexiones eléctricas entre el potenciostato y los electrodos 3 y gire el potenciostato sucesivamente. </li><li> Abrir y usar la &quot;vista de medición&quot; para ver las lecturas actuales y potenciales de corrosión medio ambiente. Durante la fase de potencial de circuito abierto (OCP), donde hay potencial de rampa se aplica todavía la lectura actual entre el trabajo (potencial positivo) y el contador (negativo) del electrodo es de alrededor de (0 ± 0,01) mu. El sellado incorrecto de la cámara con cinta PTFE puede causar fluctuaciones en la lectura de la corriente debido a la cámara que se aireó con gas nitrógeno para eliminar las moléculas de oxígeno. </li><li> Deje elmuestra se equilibre y estabilice dentro del entorno vasija de corrosión. La duración de tiempo para esto varía (1 a 6 hr) y depende de material. Monitorear el potencial de uso de vista de medición para determinar si se alcanzan las condiciones estabilizadas. El potencial será constante sin fluctuaciones cuando se alcanzan condiciones estables. </li><li> Después de que se alcancen condiciones estables, iniciar el proceso de corrosión. Sin embargo antes de que esto se puede hacer, llene el &quot;programa de la corrosión&quot; y &quot;voltametría cíclica (CV)&quot; condiciones utilizando la plantilla esqueleto proporcionado por el software analítico. </li><li> Seleccione el procedimiento de voltametría cíclica potenciostato dentro de la vista de configuración desde la pestaña procedimiento. </li><li> Habilitar los siguientes parámetros para ser incluidos en la muestra para la ejecución de la corrosión: el tiempo, el electrodo de trabajo potencial (WE), y actual de la partida a la corrosión. </li><li> Seleccione la opción de automatizar la gama actual. Ajuste la corriente más alta en el rango de ser de 10 mA, y la corriente más baja de la range sea 10 nA para la NOS. </li><li> Asegúrese de que la selección final de corte se controla a través del potencial estableciendo el parámetro atrás ciclo &#39;a 0,8 mV para permitir que el ciclo de histéresis para completar. </li><li> Registre el OCP de la vista de medición en el cuadro de texto del parámetro OCP. Establecer el inicio potencial de 100 mV por debajo del valor registrado OCP. Establecer el potencial vértice superior a 800 mV, el vértice inferior a 100 mV por debajo del potencial de inicio y parada del potencial de 100 mV por debajo del potencial vértice inferior. Ajuste la velocidad de barrido de 0.001 V / seg y el potencial paso a 0,0024 V / seg. Ahora se inicia Press. </li></ol> 5. Después de la finalización de la corrosión Run Nota: después de la finalización de la corrosión ejecutó el examen de polarización se muestra dentro de la vista de análisis del software. Para cada polarización ejecutar la vista del moderador enumera el OCP, la trama de E vs t y la escalera de CV que es un gráfico de E frente a log (i). <ol><li> Dentro de cada parcela ltinta, determinar filtración interna de los puntos de datos, la extrapolación Tafel, y las opciones de la trama. Expandir cada enlace presenta para mostrar diversos parámetros de interés, que forman colectivamente los parámetros electroquímicos. La exploración de polarización (densidad de corriente vs. potencial), determina el potencial de circuito abierto, el potencial de picadura (pit E) y el potencial de protección (E pro). </li><li> Tabular la anódico y catódico constantes Tafel, la velocidad de corrosión, la corriente de corrosión, la densidad de corriente de corrosión, el potencial de inicio, y el potencial efecto en virtud de la velocidad de corrosión utilizando el enlace pendiente de Tafel. </li></ol> 6. Eliminar el ejemplo del soporte del electrodo <ol><li> Preparar 3 pequeños frascos de 50 ml con diclorometano en la campana de humos. </li><li> Retirar las muestras analizadas de los soportes de electrodos sumergiendo el extremo inferior del soporte en diclorometano durante 30 min dentro de un humo del capó. </li><li> Una vez extraído, colocar la muestra en el siguiente vaso dediclorometano y se deja durante 15 minutos. Repita este proceso con el tercer y último enjuague para eliminar cualquier exceso de recubrimiento en las secciones de fijación de la muestra. </li><li> Limpie el sellador restante del clip y de la muestra y finalmente enjuagar con agua DI. </li></ol>

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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromium+and+cobalt+ion+concentrations+in+blood+and+serum+following+various+types+of+metal-on-metal+hip+arthroplasties:+a+literature+overview.">Chromium and cobalt ion concentrations in blood and serum following various types of metal-on-metal hip arthroplasties: a literature overview.</a> Acta Orthop. 84 (3), 229-236 (2013).</li><li>Frangini, S., De Cristofaro, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+galvanostatic+polarisation+method+for+determining+reliable+pitting+potentials+on+stainless+steels+in+crevice-free+conditions.">Analysis of galvanostatic polarisation method for determining reliable pitting potentials on stainless steels in crevice-free conditions.</a> Corros Sci. 45 (12), 2769-2786 (2002).</li></ol>

The authors have nothing to disclose.

Exploraciones de polarización producidos a partir de las muestras de acero inoxidable mostraron parcelas continuas limpias que correlacionan con exploraciones visto en la literatura indicativa de un sistema que funcione bien la corrosión, que es a la vez fiable y reproducible 29. Poor reproducibilidad de los potenciales de picaduras potenciodinámicas se identifica con una extensión de unos pocos cientos de milivoltios, con picaduras ser potencial caracterizado por un proceso estocástico 29. Es...

Las técnicas electroquímicas proporcionan un método rápido y relativamente barato de obtener las propiedades electroquímicas de un material. Estas técnicas se basan predominantemente en la capacidad de detectar la corrosión de un metal mediante la observación de la respuesta del proceso de transferencia de carga a una perturbación controlada electroquímica 1-5. La corrosión de los implantes de metal dentro de un entorno de cuerpo es crítica debido a las consecuencias adversas sobre la biocompatibilidad y el material de la integridad 6. El factor principal que contribuye a la corrosión de los implantes dentro del cuerpo es la disolución del óxido de la superficie que lleva a un aumento de la liberación de iones metálicos 7-11. Esto da lugar a reacciones biológicas adversas, que se pueden encontrar de forma local, pero con efectos potencialmente sistémicos que conducen a la falla prematura del implante 10,12-28. Las características de corrosión de un espécimen de prueba se predicen a partir de la exploración de polarización producidopor un potenciostato. Una exploración de polarización permite la extrapolación de los parámetros cinéticos y de corrosión de un sustrato metálico. Durante un análisis, la oxidación o la reducción de una especie electro-activas puede ser limitado por la transferencia de carga y el movimiento de los reactivos o productos. Todos estos factores están encapsulados por la exploración de polarización; por lo tanto, la importancia de tener un sistema que produce una exploración de polarización fiable y repetible a través de múltiples ciclos es de gran importancia. El objetivo principal de este manuscrito es proporcionar un protocolo de identificación de la lógica y las medidas adoptadas para obtener un sistema de la corrosión potenciodinámico que funcione bien.

<table><tbody><tr><td>Potentiostat</td><td>Metrohm</td><td>PGSTAT101</td><td></td></tr><tr><td>Ag/AgCl reference electrode, shielded</td><td>Metrohm</td><td>6.0729.100</td><td></td></tr><tr><td>Electrode shaft</td><td>Metrohm</td><td>6.1241.060</td><td></td></tr><tr><td>Polisher Forcipol 1v</td><td>Metkon</td><td>3602</td><td></td></tr><tr><td>Clindrical flask 700 ml</td><td>SciLabware</td><td>FR700F</td><td></td></tr><tr><td>Reaction lid</td><td>SciLabware</td><td>MAF2/41</td><td></td></tr><tr><td>Dichloromethane</td><td>Sigma-Aldrich</td><td>MKBR7629V</td><td>Use under a fumehood. Wear protective clothing.</td></tr><tr><td>Thermo / HAAKE D Series Immersion Circulators</td><td>Haake</td><td></td><td></td></tr></tbody></table>

potentiodynamic corrosion testing

Different metallic materials have different polarization characteristics as dictated by the open circuit potential, breakdown potential, and passivation potential of the material. The detection of these electrochemical parameters identifies the corrosion factors of a material. A reliable and well-functioning corrosion system is required to achieve this.
Corrosion of the samples was achieved via a potentiodynamic polarization technique employing a three-electrode configuration, consisting of reference, counter, and working electrodes. Prior to commencement a baseline potential is obtained. Following the stabilization of the corrosion potential (Ecorr), the applied potential is ramped at a slow rate in the positive direction relative to the reference electrode. The working electrode was a stainless steel screw. The reference electrode was a standard Ag/AgCl. The counter electrode used was a platinum mesh. Having a reliable and well-functioning in vitro corrosion system to test biomaterials provides an in-expensive technique that allows for the systematic characterization of the material by determining the breakdown potential, to further understand the material's response to corrosion. The goal of the protocol is to set up and run an in vitro potentiodynamic corrosion system to analyze pitting corrosion for small metallic medical devices.

A la conclusión del procedimiento de un sistema in vitro de corrosión está configurada para llevar a cabo estudios de corrosión. Los procedimientos específicos, tales como la limpieza de la vasija de corrosión y la jaula de Faraday se introdujeron en el protocolo para mejorar el rendimiento de ruido. El concepto fundamental de una buena exploración de polarización es identificar las condiciones electro-físicas del material proporcionando información valiosa para compre...

Watch this Scientific Journal Video about Potentiodynamic Corrosion Testing at JoVE.com

Potentiodynamic Corrosion Testing

Here, we present a protocol to set up and run an in vitro potentiodynamic corrosion system to analyze pitting corrosion for small metallic medical devices.

Potenciodinámico Pruebas de Corrosión

Different metallic materials have different polarization characteristics as dictated by the open circuit potential, breakdown potential, and passivation ...

Universidad San Sebastian

Research

JoVE Journal

Environment

17.5K vistas.  Prince of Wales Clinical School. Here, we present a protocol to set up and run an in vitro potentiodynamic corrosion system to analyze pitting corrosion for small metallic medical devices. 

Video: Potentiodynamic Corrosion Testing

Metal Corrosion and the Efficiency of Corrosion Inhibitors in Less Conductive Media

Material corrosion can be a limiting factor for different materials in many applications. Thus, it is necessary to better understand corrosion processes, prevent them and minimize the damages associated with them. One of the most important characteristics of corrosion processes is the corrosion rate. The measurement of corrosion rates is often very difficult or even impossible especially in less conductive, non-aqueous environments such as biofuels. Here, we present five different methods for the determination of corrosion rates and the efficiency of anti-corrosion protection in biofuels: (i) a static test, (ii) a dynamic test, (iii) a static test with a reflux cooler and electrochemical measurements (iv) in a two-electrode arrangement and (v) in a three-electrode arrangement. The static test is advantageous due to its low demands on material and instrumental equipment. The dynamic test allows for the testing of corrosion rates of metallic materials at more severe conditions. The static test with a reflux cooler allows for the testing in environments with higher viscosity (e.g., engine oils) at higher temperatures in the presence of oxidation or an inert atmosphere. The electrochemical measurements provide a more comprehensive view on corrosion processes. The presented cell geometries and arrangements (the two-electrode and three-electrode systems) make it possible to perform measurements in biofuel environments without base electrolytes that could have a negative impact on the results and load them with measurement errors. The presented methods make it possible to study the corrosion aggressiveness of an environment, the corrosion resistance of metallic materials, and the efficiency of corrosion inhibitors with representative and reproducible results. The results obtained using these methods can help to understand corrosion processes in more detail to minimize the damages caused by corrosion.

The testing of processes associated with material corrosion can often be difficult especially in non-aqueous environments. Here, we present different methods for short-term and long-term testing of corrosion behavior of non-aqueous environments such as biofuels, especially those containing bioethanol.

Corrosión de metales y la eficacia de los inhibidores de la corrosión en medios menos conductivos

Material corrosion can be a limiting factor for different materials in many applications. Thus, it is necessary to better understand corrosion processes, ...

Investigación

Medio ambiente

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Espectroscopia de impedancia electroquímica como herramienta para la valoración constante de tipo electroquímico

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Química

Synthesis of Platinum-nickel Nanowires and Optimization for Oxygen Reduction Performance

Platinum-nickel (Pt-Ni) nanowires were developed as fuel cell electrocatalysts, and were optimized for the performance and durability in the oxygen reduction reaction. Spontaneous galvanic displacement was used to deposit Pt layers onto Ni nanowire substrates. The synthesis approach produced catalysts with high specific activities and high Pt surface areas. Hydrogen annealing improved Pt and Ni mixing and specific activity. Acid leaching was used to preferentially remove Ni near the nanowire surface, and oxygen annealing was used to stabilize near-surface Ni, improving durability and minimizing Ni dissolution. These protocols detail the optimization of each post-synthesis processing step, including hydrogen annealing to 250 &#176;C, exposure to 0.1 M nitric acid, and oxygen annealing to 175 &#176;C. Through these steps, Pt-Ni nanowires produced increased activities more than an order of magnitude than Pt nanoparticles, while offering significant durability improvements. The presented protocols are based on Pt-Ni systems in the development of fuel cell catalysts. These techniques have also been used for a variety of metal combinations, and can be applied to develop catalysts for a number of electrochemical processes.

&#160; The protocol describes the synthesis and electrochemical testing of platinum-nickel nanowires. Nanowires were synthesized by the galvanic displacement of a nickel nanowire template. Post-synthesis processing, including hydrogen annealing, acid leaching, and oxygen annealing were used to optimize nanowire performance and durability in the oxygen reduction reaction.

Síntesis de nanocables de platino y níquel y optimización de rendimiento de reducción de oxígeno

Platinum-nickel (Pt-Ni) nanowires were developed as fuel cell electrocatalysts, and were optimized for the performance and durability in the oxygen ...

Experimental Protocol to Determine the Chloride Threshold Value for Corrosion in Samples Taken from Reinforced Concrete Structures

The aging of reinforced concrete infrastructure in developed countries imposes an urgent need for methods to reliably assess the condition of these structures. Corrosion of the embedded reinforcing steel is the most frequent cause for degradation. While it is well known that the ability of a structure to withstand corrosion depends strongly on factors such as the materials used or the age, it is common practice to rely on threshold values stipulated in standards or textbooks. These threshold values for corrosion initiation (Ccrit) are independent of the actual properties of a certain structure, which clearly limits the accuracy of condition assessments and service life predictions. The practice of using tabulated values can be traced to the lack of reliable methods to determine Ccrit on-site and in the laboratory.
Here, an experimental protocol to determine Ccrit for individual engineering structures or structural members is presented. A number of reinforced concrete samples are taken from structures and laboratory corrosion testing is performed. The main advantage of this method is that it ensures real conditions concerning parameters that are well known to greatly influence Ccrit, such as the steel-concrete interface, which cannot be representatively mimicked in laboratory-produced samples. At the same time, the accelerated corrosion test in the laboratory permits the reliable determination of Ccrit prior to corrosion initiation on the tested structure; this is a major advantage over all common condition assessment methods that only permit estimating the conditions for corrosion after initiation, i.e., when the structure is already damaged.
The protocol yields the statistical distribution of Ccrit for the tested structure. This serves as a basis for probabilistic prediction models for the remaining time to corrosion, which is needed for maintenance planning. This method can potentially be used in material testing of civil infrastructures, similar to established methods used for mechanical testing.

We propose a method to measure a parameter that is highly relevant for corrosion assessments or predictions of reinforced concrete structures, with the main advantage of permitting testing of samples from engineering structures. This ensures real conditions at the steel-concrete interface, which are crucial to avoid artifacts of laboratory-made samples.

Protocolo experimental para determinar el valor de umbral de cloruro para la corrosión en las muestras tomadas de estructuras de hormigón armado

The aging of reinforced concrete infrastructure in developed countries imposes an urgent need for methods to reliably assess the condition of these ...

Ingeniería

Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline earth-liquid metal alloys as functions of both composition and temperature in order to acquire thermodynamic data. The cell consists of a chemically stable solid-state CaF2-AF2 electrolyte (where A is the alkaline-earth element such as Ca, Sr, or Ba), with binary A-B alloy (where B is the liquid metal such as Bi or Sb) working electrodes, and a pure A metal reference electrode. Emf data are collected over a temperature range of 723 K to 1,123 K in 25 K increments for multiple alloy compositions per experiment and the results are analyzed to yield activity values, phase transition temperatures, and partial molar entropies/enthalpies for each composition.

This protocol describes the measurement of the electromotive force of alkaline-earth elements in liquid metal alloys at high temperatures (723-1,123 K) to determine their thermodynamic properties, including activity, partial molar entropy, partial molar enthalpy, and phase transition temperatures, over a wide composition range.

Determinación de propiedades termodinámicas de aleaciones de metales alcalinotérreos-líquido utilizando la técnica de la fuerza electromotriz

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline ...

Applicability Analysis of Assessment Methods for Morphological Parameters of Corroded Steel Bars

The irregular and uneven residual sections along the length of a corroded steel bar substantially change its mechanical properties and significantly dominate the safety and performance of an existing concrete structure. As a result, it is important to measure the geometry and amount of corrosion of a steel bar in a structure properly to assess the residual bearing capacity and service life of the structure. This paper introduces and compares five different methods for measuring the geometry and amount of corrosion of a steel bar. A single 500 mm long and 14 mm diameter steel bar is the specimen that is subjected to accelerated corrosion in this protocol. Its morphology and the amount of corrosion were carefully measured before and after using mass loss measurements, a Vernier caliper, drainage measurements, 3D scanning, and X-ray micro-computed tomography (XCT). The applicability and suitability of these different methods were then evaluated. The results show that the Vernier caliper is the best choice for measuring the morphology of a non-corroded bar, while 3D scanning is the most suitable for quantifying the morphology of a corroded bar.

This paper measures the geometry and the amount of corrosion of a steel bar using different methods: mass loss, calipers, drainage measurements, 3D scanning, and X-ray micro-computed tomography (XCT).

Análisis de la aplicabilidad de los métodos de evaluación de parámetros morfológicos de las barras de acero corroído

The irregular and uneven residual sections along the length of a corroded steel bar substantially change its mechanical properties and significantly ...

Determining Tribocorrosion Rate and Wear-Corrosion Synergy of Bulk and Thin Film Aluminum Alloys

The increasing complexity and severity of service conditions in areas, such as aerospace and marine industries, nuclear systems, microelectronics, batteries, and biomedical devices, etc., impose great challenges on the reliable performance of alloys exposed to extreme conditions where mechanical and electrochemical attack co-exist. Finding ways for alloys to mitigate the combined attack of wear and corrosion (i.e., tribocorrosion) under such extreme conditions is thus highly critical for improving their reliability and service lifetime when used in such conditions. The challenge lies in the fact that wear and corrosion are not independent of each other, but rather work synergistically to accelerate the total material loss. Thus, a reliable method to evaluate the tribocorrosion resistance of metals and alloys is needed. Here, a protocol for measuring the tribocorrosion rate and wear-corrosion synergy of Al-based bulk and thin film samples in a corrosive environment under room temperature is presented.

Here, we present a protocol to measure the tribocorrosion rate and wear-corrosion synergy of thin film and bulk Al alloys in simulated sea water at room temperature.

Determinación de tasa de tribocorrosión y sinergia corrosión desgaste de película a granel y delgadas de aleaciones de aluminio

The increasing complexity and severity of service conditions in areas, such as aerospace and marine industries, nuclear systems, microelectronics, ...

Electrochemical Roughening of Thin-Film Platinum Macro and Microelectrodes

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries of the metal. Using this method, a crack free, thin-film macroelectrode surface with up to 40 times increase in active surface area was obtained. The roughening is easy to do in a standard electrochemical characterization laboratory and incudes the application of voltage pulses followed by extended application of a reductive voltage in a perchloric acid solution. The protocol includes the chemical and electrochemical preparation of both a macroscale (1.2 mm diameter) and microscale (20 &#181;m diameter) platinum disc electrode surface, roughening the electrode surface and characterizing the effects of surface roughening on electrode active surface area. This electrochemical characterization includes cyclic voltammetry and impedance spectroscopy and is demonstrated for both the macroelectrodes and the microelectrodes. Roughening increases electrode active surface area, decreases electrode impedance, increases platinum charge injection limits to those of titanium nitride electrodes of same geometry and improves substrates for adhesion of electrochemically deposited films.

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries. The electrochemical techniques of cyclic voltammetry and impedance spectroscopy are demonstrated to characterize these electrode surfaces.

Desbaste electroquímico de macro y microelectrodos de platino de película delgada

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries ...

Applying Dynamic Strain on Thin Oxide Films Immobilized on a Pseudoelastic Nickel-Titanium Alloy

Direct alteration of material structure/function through strain is a growing area of research that has allowed for novel properties of materials to emerge. Tuning material structure can be achieved by controlling an external force imposed on materials and inducing stress-strain responses (i.e., applying dynamic strain). Electroactive thin films are typically deposited on shape or volume tunable elastic substrates, where mechanical loading (i.e., compression or tension) can affect film structure and function through imposed strain. Here, we summarize methods for straining n-type doped titanium dioxide (TiO2) films prepared by a thermal treatment of a pseudo-elastic nickel-titanium alloy (Nitinol). The main purpose of the described methods is to study how strain affects electrocatalytic activities of metal oxide, specifically hydrogen evolution and oxygen evolution reactions. The same system can be adapted to study the effect of strain more broadly. Strain engineering can be applied for optimization of a material function, as well as for design of adjustable, multifunctional (photo)electrocatalytic materials under external stress control.

Dynamic, tensile strain is applied on TiO2 thin films to study the effects of strain on electrocatalysis, specifically proton reduction and water oxidation. TiO2 films are prepared by thermal treatment of the pseudo-elastic NiTi alloy (Nitinol).

Aplicación de tensión dinámica en películas de óxido fino inmovilizadas en una aleación pseudoelástica de níquel y titanio

Direct alteration of material structure/function through strain is a growing area of research that has allowed for novel properties of materials to ...

Electrochemical Measurements of Supported Catalysts Using a Potentiostat/Galvanostat

Source: Laboratory of Dr. Yuriy Rom&#225;n &#8212; Massachusetts Institute of Technology
A potentiostat/galvanostat (often referred to as simply a potentiostat) is an instrument that measures current at an applied potential (potentiostatic operation) or measures potential at an applied current (galvanostatic operation) (Figure 1). It is the most commonly used instrument in the electrochemical characterization of anode and cathode materials for fuel cells, electrolyzers, batteries, and supercapacitors.
Conventionally, these anode and cathode materials are interfaced with a potentiostat via a three-electrode electrochemical cell. The electrode leads from the potentiostat are connected to the reference electrode, the counter electrode (often called the auxiliary electrode), and the working electrode (which contains the test material of interest). The electrochemical cell is then filled with a high ionic strength electrolyte solution, such as an acidic, alkaline, or salt solution. The media for this high ionic strength solution is typically aqueous; however, for applications necessitating higher operating cell potential windows, such as batteries and supercapacitors, non-aqueous media is often used. The cell media is degassed with an inert gas (to prevent unwanted side reactions) or with a test gas (if the test reaction involves a gas at one of the electrodes).
Alternatively, a salt bridge or membrane is employed to maintain ionic contact if the two half cells are to be measured in different electrolytes. In heterogeneous electrocatalysis, this type of &#34;two compartment&#34; cell is often used if the test molecule at the working electrode is also reactive at the counterelectrode. This happens frequently as the counterelectrode typically employed is platinum, which is a highly active catalyst for many reactions. Here, single compartment cells will be used, where all three electrodes are in the same media.
This video will explain the process of polishing a working electrode, preparing a catalyst ink, mounting the catalyst ink onto the working electrode, preparing the electrochemical cell, and then performing electrochemical measurements. The measurements that are performed include: cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronopotentiometry (CP), and chronoamperometry (CA).
<img alt="Figure 1" src="/files/ftp_upload/5698/5698fig1.jpg" /> 
Figure 1. An example of a single compartment electrochemical cell. a.) Teflon cap, b.) glass cell, c.) Pt wire counter electrode, d.) working electrode, e.) Ag/AgCl reference electrode, f.) 0.5 M aqueous sulfuric acid electrolyte solution.