|Posted by jimbo on July 02, 2004 at 02:26:20:|
|In response to Re: electrolysis|
:There is a pyhsical property of materials called the electromotive series, also referred to as the nobility series. Any two metals, when placed in an electrolyte solution ( e.g. water) a difference of potential is formed which causes current to flow. Per the nobility series, the further apart the two materials are on the scale, the greater the potential. Also, the material higher on the chart (more "noble") will be protected, and the material lower on the chart will "sacrifice" itself, or corrode.
Copper is fairly high on the chart (gold on top), steel is much lower. Zinc (galvanizd coating) is so low it is frequently used as a scarificial anode in naval and marine applications to protect the hull of ships and boats.
In a dielectric nipple, the plastic lining prevents the water from ever touching the galvanized coating. In a dielectric union, the two metals are physically separated by a dielectric (non-conducting) material, so that a complete electric circuit cannot be formed.