Characterising nonuniform electrodeposition and electrodissolution using the novel wire beam electrode method

An electrochemically integrated multi-electrode system namely the wire beam electrode (WBE) has been applied as a new method of characterising nonuniform electrodeposition and electrodissolution, by measuring and identifying characteristic patterns in electrodeposition and electrodissolution current distribution maps. Various patterns of electrodeposition current distribution have been obtained from Watts nickel plating and bright acid copper plating baths with the effects of several affecting factors such as bath concentration, temperature, agitation and electrolyte flow. Typical patterns of electrodissolution current distribution have also been detected over a WBE surface under anodic dissolution. This work suggests that the WBE method can be used as a new tool for monitoring, characterising and optimising electrodeposition and electrodissolution processes in the laboratory, and can also be applied as an experimental method to verify the accuracy and completeness of mathematical models for electrodeposition and electrodissolution.

A novel crevice corrosion experiment using a wire beam electrode

This paper describes a new experiment for studying crevice corrosion. A wire beam electrode was employed in this experiment to measure electrochemical parameters directly from crevice area and these parameters were used to calculate instantaneous crevice corrosion kinetics. A clear correlation between calculated corrosion depth map and real corrosion appearance was obtained.

Studying non-uniform electrodeposition using the wire beam electrode method

Nonuniform electrodeposition is a major concern in almost every practical electrodeposition application. The ablility to control nonuniformity in electrodeposition is the key to successful plating for corrosion resistance, and more especially to meeting the very exacting requirements of electroforming, electrodeposition. This paper presents a novel technique namely the wire beam electrode (WBE) for characterizing and monitoring nonuniform electroplating processes. For the first time, the nonuniform distribution of electroplating currents (NDEC) has been mapped. Preliminary experimental results indicated that electrochemical heterogeneity was the key factor affecting NDEC. The secondary current distribution, rather than the primary current distribution, played a major role in determining the NDEC. This work suggests that the WBE is a practical tool for characterizing and optimizing electrodeposition processes and for verifying the accuracy and completeness of mathematic modelling of electrodeposition processes.

An auto-switch for multisampling of a wire beam electrode corrosion monitoring system

An auto-switch device has been designed, constructed, and tested for multisensor corrosion measurements. The auto-switch is able to connect/disconnect the selected wire beam electrode and/or electrode pairs under computer control. A computer controlled analog switch-array consisting of 100 inputs has been used as an essential part of the switch bank. The switch-bank is an essential component of a corrosion-monitoring instrument that is expected to find wide application in industry. The performance of the switch-bank is discussed and its effect on the signals is illustrated.

Quantifying the efficiency and understanding the mechanism of localised corrosion inhibition using the wire beam electrode

Parameters extracted from the wire beam electrode (WBE) galvanic current maps have been used in conjunction with electrochemical noise patterns to directly quantify the degree of localised corrosion inhibition provided by inhibitors and to understand the mechanism of localised corrosion inhibition. The behaviour of two traditional localised corrosion inhibitors has been assessed by their effects on the maximum anodic current density (imax), total anodic current density (itot), the number of anodic sites (Na) and the localised corrosion intensity index (LCII). Typical experiments are presented to illustrate the application of these parameters in providing useful information on the efficiency and mechanism of localised corrosion inhibition.

Localized corrosion and inhibition studies using the wire beam electrode in conjunction with the electrochemical noise analysis and the scanning reference electrode techniques

Several new technical developments have been made based on the combined use of the wire beam electrode (WBE), electrochemical noise analysis (ENA) and the scanning reference electrode technique (SRET). These have included: (i) The WBE-R n method- the combined use of the WBE and the noise resistance (Rn) to map the rates and patterns of uniform or localized corrosion; (ii) The WBE-Noise Signatures method- the combined use of the WBE and the noise signature to detect the origination and propagation of localized corrosion; and (iii) The WBE-SRET method- the combined use of the WBE and SRET to investigate localized corrosion from both the metallic and electrolyte phases of a corroding metal surface. This paper presents a brief review on these novel methods and their applications for detecting general and localized corrosion, for mapping the rates of corrosion, and for studying corrosion inhibitors.