Net Boat Talk

Go Back   Net Boat Talk > Boat Talk > RSS (Really Simple Syndication) feed

RSS (Really Simple Syndication) feed Autmated feed

Reply
 
Thread Tools Display Modes
  #1  
Old 09-08-2012, 04:37 PM
RSS_user RSS_user is offline
Senior Member
 

Join Date: Nov 2008
Posts: 2,116
RSS_user is on a distinguished road
Default Galvanic Corrosion - One of the Biggest Enemies in the Water

Hello, I wanted to write today to talk about galvanic corrosion. For those of you not familiar with galvanic corrosion it is an electrochemical reaction when one metal corrodes from another when both are immersed in an electrolyte that is conductive (such as sea water). Dissimilar metals and metal alloys have different electrode potentials when two or more of these metals exist in the same electrolyte. When this happens a galvanic couple is created and depending upon the nobility of the metal (which I will talk about further on in this article) one metal will become the anode and another metal will become the cathode (both are electrodes). To explain the difference between an anode and a cathode in simplest terms, an anode is the metal that current flows in to, a cathode is the metal that current flows out from. Do not confuse an anode and cathode with positive or negative charges or voltage. An anode and cathode can both be positively charged. It is the direction of current flow between the two metals that matters. Once the galvanic couple is formed between the two metals, the anode metal will dissolve into the electrolyte (the sea water). During this process the charged ions and atoms are interchanged with electrons at the electrodes and pass through the sea water. This process is known as electrolysis. In a simple way to explain this, electricity passing through the water between two electrodes is electrolysis. The resulting reaction is galvanic corrosion. The rate at which this occurs is dependant on water temperature, the salinity in the water, nearby dissimilar metals in the water, and free flowing current that may exist in the water. This galvanic couple process is how a common household battery works. The result is the electric current produced from the reaction. Given the size of a body of water (such as in a salt water river at a marina) this electrochemical reaction can be measured in millivolts (mV).



More...
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump







All times are GMT -4. The time now is 05:43 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.