UFC 3-570-06
JANUARY 31 2003
For an electrode to be used as a reference to measure other electrodes, the metal and
the electrolyte in contact with the metal must be specified. Once this is done, the
electrode becomes a reference electrode.
Many types of reference electrodes have been used. In the laboratory the
hydrogen/hydrogen (hydrogen electrode, hydrogen electrolyte) is common. For field
use, the copper/copper sulfate (copper electrode, fully saturated copper sulfate
electrolyte) is in common use, except in salt water, where silver/silver chloride (silver
electrode, silver chloride electrolyte) is used and must be adjusted by the factor or the
chloride contact of the electrolyte. These references are merely stable electrodes with a
known potential used to measure the potential of unknown electrodes. Using these
references, the potential value of any metal in any electrolyte can be recorded for future
reference and compared to other electrodes. A table of such measurement is called a
galvanic series of measurements. Each table must specify the reference electrode
used to accomplish the measurements, and the electrolyte the unknown electrodes
were in, to allow for interpretation by corrosion experts. This series can then be used to
determine which electrode will be the anode (and corrode) in an electrochemical
corrosion cell.
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