1. Open a standard ECN file containing corrosion potential and corrosion current data.
Use File-> Open or press the Speed Button
1.1 The software responds with a file open dialog , Select your ECN file.
Figure 23.0 ECN file open dialog box, ECN Analysis Version 1.0 .
A typical Electro Chemical Noise (ECN) file is shown below. This software expects the first column to be the time values, the second column to be the corrosion current in (amperes) and the third column as the corrosion potential ( in milli volts).
Figure 24.0 A typical Electro Chemical Noise (ECN) File.
1.2 If the file read is success, the software displays the following messages with the size of allocated memory and record length.
1.3 The time record window for Both Potential and Current gets updated with the newly read content of the ECN file.
Figure 25.0 The time record window of ECN analysis version 1.0
2.0 Setting the parameters for Processing.
2.1 Go to Preference Menu' -> Processing Preference.
Software responds with a separate dialog Box and prompts the user to enter the processing parameters.The user enter the various parameters like length of FFT, the type of FFT window to be used etc.
Figure 26.0 The Preferences window of ECN Analysis version 1.0
|•||Sampling Interval / s|
The sampling rate originally used in your experiment needs to entered on the sampling rate box, the time column of the input file will be ignored.
The software calculates noise impedance from power spectral densities of potential and current. The noise impedance spectrum is usually noisy and to improve readability a number of impedance spectra from adjacent segments can be used to obtain an averaged impedance spectrum.The number of spectra for the calculation can be entered here.
|•||Points Average for Low-Frequency Limit|
Low-frequency impedance and low-frequency limits of potential and current power spectral densities (required to estimate charge and frequency of corrosion events) are calculated by averaging some points in the low frequency regions of the impedance spectrum. The number of points (and therefore the frequency range) used to extract low-frequency limits can be entered here.
|•||Stern Geary Coefficient / V|
The Stern-Geary coefficient is required to obtain accurate estimation of charge and frequency of corrosion events. Make sure that you enter the appropriate Stern-Geary coefficient for the material/environment combination that you are studying.
|•||Skip Iterations Between Saved Spectra|
This software allows you to save complete Potential PSD & Current PSD spectra periodically. This parameters indicates how often complete spectra are saved to the disk. The lower the number, the higher the number of spectra saved. Prior to the start of the processing, the software asks the user if spectra need to be saved. If 'NO' is selected, the Skip Interactions Between Saved Spectra parameter has no effect. Generally, it is not required to save the spectra periodically and a 'NO' should be selected prior to starting the processing.
|•||Segments Overlap %|
The distance between the first point of one segment and the first point of the following segment is specified in Segment Overlap %. The default value is 95%. High overlap produce more accurate results and enables to use more heavy time-averaging without compromising time resolution, but increases processing time. For very long dataset it is suggested to use small overlap percentage.
2.0 To Process your file either go to the menu item ' Processing -> Start ' or use the speed button
The software starts to process the file and the processing your selected file. The progress can be monitored on the Time Record tab. The time associated to the segment that is being currently processed is highlighted with a diamond shape on the potential and current time records. The Progress is also visible on the Progress bar .
3.0 What all I can explore during and after Processing ?
The software allows you to visualize the potential and current segments that are currently being processed in the ' Processing ' tab. In the top part the current segment and the potential segment are shown. The software removes DC drift ( or trend ) in the time record by linear curve fitting and displays the result in the central graphs. The bottom graphs shows the Power Spectral densities calculated using FFT method, which is obtained from the potential and current segments.
Figure 27.0 The Processing tab of ECN version 1.0 This tab shows a segment of potential, current and the same after the trend is removed. The Bottom two graphs are the power spectral densities of current and potential respectively.
The third tab (PSD) provides you with the noise impedance calculated from these 2 PSD's. The graph on the bottom is the Average impedance obtained after averaging few impedance spectra specified by ' No of spectra to average' in the preference window. The fourth tab ( Resistance / Charge / Frequency ) provides you with Noise impedance , Noise resistance, Charge and the frequency of events. Figure below shows a typical record.
Figure 28.0 The Results tab of ECN Analysis version 1.0. It provides low-frequency Noise impedance , Noise Resistance ,Average charge and Frequency of corrosion events.