Experimental Sequence

Run the ASTM CPT standard technique by selecting Experiment>Critical Pitting Temperature>ASTM Critical Pitting Temperature from the Framework™ menu bar. This initiates the following sequence of events:

  1. Framework creates a Runner window, and the ASTM Critical Pitting Temperature.exp script is run in this window.
  2. In the runner window, the script displays a Setup dialog box which becomes the active window. This dialog box allows you to view and edit the experiment parameters. Clicking the OK button accepts the parameters and starts the experimental run.
  3. The script now obtains the use of the potentiostat and temperature controller specified during setup, and opens the data file specified in the Output File field of the Setup dialog box. If the potentiostat or controller is in use, or the data file cannot be opened, the script returns you to the Setup dialog box.
  4. All header information is written to the data file. Header information consists of the analysis tag, the time and date the experiment was started and a list of the setup parameters.
  5. The script conditions the electrode if Conditioning was specified in the Setup. Conditioning is done by applying a fixed potential for a defined time. It establishes a known surface state on the corrosion specimen. A plot of current versus time is displayed during the Conditioning.
  6. The cell is turned off and the specimen's Eoc is measured.
  7. If an Initial Delay is turned on in the Setup, this step lasts for the time specified as the Initial Delay time, or until the potential stabilizes . If no Initial Delay is specified, this step only lasts long enough for Eoc to be measured. A plot of potential versus time is always displayed. The last measured potential is recorded as Eoc.
  8. The potential is set to the Applied E parameter value entered in Setup, and the Cell is turned on. The temperature is set to Start Temp., and the system delays until the measured cell temperature reached this requested value. A current and measured temperature point is recorded. The temperature is stepped by the forward step size and the script pauses for one sample period. Another current and measured temperature point is recorded. NOTE: The measured temperature and the requested temperature can be different if the temperature sweep rate is too high for the cell's thermal time constant. This process of stepping the temperature, delaying and then recording a point continues until the requested temperature reaches the Final Temp. During this stepping process, the measured current is compared to the Stop criteria. If the measured current exceeds the stop criteria for the Duration specified, the experiment will end. Otherwise, the experiment will continue until the requested temperature reaches the Final Temp.
  9. The scan ends and the data is written to the data file. The plot continues to be displayed until you click the Skip button.