Electrochemical noise diagnostics: Analysis of algorithm of orthogonal expansions

Abstract

INRODUCTIONThe fluctuations in the electrochemical systems have a pronounced effect on the rate of all electro chemical processes [1]. The internal heat fluctuations determine the emergence of random fluctuations of electrical voltage and electrical current. Both fluctua tions can be recorded with a sensitive device as the electrochemical noise. The electrochemical noise is caused by random (in the microscopic sense) electro chemical processes and carriers the information about the internal state of the electrochemical system. This fact is used in the noise methods of investigation of electrochemical systems and in the technologies of noise diagnostics of objects and devices of electro chemical energetics.The main principle of electrochemical noise diag nostics can be explained by the following simple example. Assume that we have the results of long term observations of fluctuations of electrical double layer charge, which were obtained by recording equilibrium fluctuations of electrode potential. Determining dis persion of heat fluctuations of charge Q on the capacitance C of electrical double layer from the noise 2 ( ) Q σ measurements and using equation (1) of Gibbs statis tical thermodynamics(1) (where k B is the Boltzmann constant and T is the tem perature), the noise electrical double layer capacitance C can be estimated.In this case, if two electrodes (an electrode, which operated for a long time, and a new electrode) are available, these electrodes can be distinguished by the noise electrical double layer capacitance and, thus, the electrochemical noise diagnostics of the electrodes can be performed.In contrast to many other electrochemical diag nostic methods, the electrochemical noise diagnostics does not require the application of perturbations in the form of electric current or voltage onto the test system. This is the advantage of electrochemical noise diag nostics. Its drawbacks are very high requirements on the measuring instruments, the necessity of large number of experimental data, and rather complicated algorithms of diagnostic information extraction.In this work, the attention focusses on the algo rithm of spectral analysis, which is based on the theory of orthogonal expansions. Far from complete list of lit erature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] reflects the interdisciplinary characterAbstract-The algorithm of orthogonal expansions is applied to the problem of extraction of diagnostic information from random noise. It is shown that the spectral analysis of electrochemical noise can be per formed by a unified algorithm regardless of the type of orthogonal expansion used. A multi channel indicator of color of electrochemical noise can be constructed on the basis of the orthogonal expansions. It is con cluded that the algorithm of orthogonal expansions is an advantageous tool for noise monitoring and noise diagnostics of practically important electrochemical devices, including the devices of electrochemical ener getics and systems of protection against corros...

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