Search Results for electrochemical methods

This article reviews the fundamentals of electrochemical corrosion test methods. The features and requirements of the instrumentation needed for an electrochemical test are briefly discussed. The article provides a discussion on the various electrochemical techniques and tests available for laboratory studies of corrosion phenomena. The techniques and tests include no-applied-signal tests, small-signal polarization tests, large-signal polarization tests, scanning electrode techniques, and miscellaneous techniques.

This article describes various methods of electrochemical analysis, namely coulometry, electrogravimetry, voltammetry, electrometric titration, and nanometer electrochemistry. The discussion covers the general uses, sample requirements, application examples, advantages, and limitations of these methods. Some of the factors pertinent to electrochemical cells are also provided. In addition, the article provides information on various potentiometric membrane electrodes used to quantify numerous ionic and nonionic species.

This article addresses electrochemical methods for instantaneous rate determination and threshold determination as well as nonelectrochemical methods that can determine incremental or cumulative rates of corrosion. Electrochemical methods for the study of galvanic corrosion rates and localized corrosion and evaluation of corrosion rates under paints are also discussed. The article describes nonelectrochemical methods that can determine incremental or cumulative rates of corrosion. Methods presented include polarization methods, polarization resistance methods, electrochemical impedance methods, frequency modulation methods, electrochemical noise resistance, potential probe methods, cyclic potentiodynamic polarization methods, potentiostatic and galvanostatic methods, electrochemical noise (EN) methods, scratch-repassivation method, and electrochemical impedance spectroscopy (EIS) techniques. Gravimetric determination of mass loss, electrical-resistance methods, magnetic methods, quartz crystal microbalance method, solution analysis methods, and metrological methods are nonelectrochemical methods. The article presents an electrochemical test that examines the susceptibility of stainless steel alloys to intergranular corrosion.

This article focuses on the methods that are being developed for detecting and monitoring corrosion: electrochemical methods, electromagnetic or sound wave methods, fiber-optic technology, fluorescence methods, and the Diffracto Sight method. It reviews the importance of data management and the Corrosion Expert System. It concludes with information on the simulation and modeling for incorporating the mechanisms of corrosion prevention into military hardware systems design and operation.

This article tabulates the chemical composition of iron-base, titanium-base, and cobalt-base alloys and illustrates the microstructures of these materials. It discusses the surface morphology and chemistry of oxide-film-covered alloys and provides insights into the interaction. The article illustrates the interfacial structure of a biomaterial surface contacting with the biological environment. It describes the corrosion behavior of stainless steel, cobalt-base alloy, and titanium alloys. The electrochemical methods used for studying metallic biomaterials corrosion are also discussed. The article concludes with information on the biological consequences of in vivo corrosion and biocompatibility.

Bridges and highways are core components of transportation system and range from pavements with earth, gravel, or stone covered by a thin bituminous surface course to a continually reinforced Portland cement concrete (PCC) roadway with or without a bituminous wear course. This article provides information on bridges and dowels and the reinforcement used in PCC roadways that suffer from corrosion. An overview is provided on the rise in awareness of the corrosion issues affecting bridges and highways. The chemistry and structure of concrete and its role as an electrolyte in promoting corrosion are also discussed. The article addresses reinforcement, including conventional, prestressed, cable stays, and corrosion-resistant reinforcement. It deals with the electrochemical methods for the inspection and corrosion control of embedded reinforcement. The article also reviews the corrosion of metal bridges and corrosion control, including the use of weathering steels and coating systems.

Corrosion monitoring is important in the operation of modern industrial plants and in the use and maintenance of expensive assets such as bridges and aircrafts, because the damage caused by corrosion and the rate of the deterioration can be huge and the risks devastating. This article discusses the system considerations and installation techniques of different types of direct and indirect techniques in electrochemically based on-line corrosion monitoring process. It describes the importance of probe location and on-line corrosion monitoring techniques with examples.

This article provides a discussion on the operation of various methods and sensors that have been used or have the potential to be used for on-line, real-time monitoring of localized corrosion. These include the electrochemical noise (ECN) method, nonelectrochemical methods, the galvanically coupled differential flow cell, galvanically coupled crevice cell, coupled multielectrode sensor, and electrochemical biofilm activity sensor.

This article describes the criteria for selecting a corrosion-monitoring method used in industrial plants. It provides a detailed discussion on the design, advantages, and disadvantages of plant corrosion-testing program. The basic types of racks used to support and insulate the coupons are also discussed. The analysis of electrical-resistance probes, sentry holes, side-stream loop, electrochemical noise, hydrogen-probe, and process streams are used to monitor and estimate corrosion rates. The corrosion rates can also be estimated by ultrasonic thickness measurements, polarization-resistance measurements, corrosion potential measurements, and alternating current impedance measurements. Corrosion monitoring strategies, such as locations, data analysis, redundancy, and other issues, are discussed. The article concludes with information on the interpretation and reporting of corrosion testing.

A variety of electrochemical techniques are used to detect and monitor material deterioration in service or in the field. This article describes the static or direct current measurements in a number of applications, including buried pipelines and storage tanks. It reviews the electrochemical impedance spectroscopy and electrochemical noise measurements in a laboratory, especially for the inspection of coatings.

Pitting is a form of localized corrosion that is often a concern in applications involving passivating metals and alloys in aggressive environments. This article describes the test methods for pitting corrosion. These methods include ASTM G 48, ASTM F 746, ASTM G 61, ASTM G 100, and electrochemical noise measurements. The visual examination, metallographic examination, and nondestructive inspection of pits are discussed. The article reviews the procedures for the use of standard charts, metal penetration, statistical analysis, and loss in mechanical properties to quantify the severity of pitting damage.

This article presents a brief history and the uses of the anodic protection technique. It compares anodic and cathodic protection and describes the design considerations of the anodic protection system. The article discusses the specific requirements of equipment required for anodic protection. It also explains the applications and economic aspects of anodic protection, with examples.

Corrosion of metallic materials is governed by electrochemical kinetics, so that the general concepts developed for studying electrochemical reaction mechanisms may be applied to corrosion. This article presents the fundamental aspects of electrode kinetics. The processes of charge transfer taking place at the electrode interface within the double layer and of mass transport at the vicinity of the electrode surface are discussed. The article describes the corrosion processes, which involve anodic and cathodic reactions at specific electrode sites. Some experimental methods for devising a reliable reaction model are detailed. The article explains some reaction mechanisms for cathodic and anodic processes to illustrate the great variety of reaction mechanisms occurring at the electrode interface.

This article describes the various characteristics of electrochemical grinding (ECG). It discusses grinding methods that can be performed with ECG components, namely, the electrolyte delivery and circulating system, the electrolyte, the DC power supply, grinding wheel, and the workpiece. Grinding, surface grinding, internal grinding, form grinding, and cylindrical grinding are discussed. The article also lists the advantages, disadvantages, and applications of ECG.