Summary for corrosion electrolyte Discussion
corrosion electrolyte testing is discussed in the context of why neutral salt solutions such as 3.5% NaCl or salt spray are commonly used. Dr. Gayathri Srinivasan asked why seawater-like conditions are considered suitable even though the solution is neutral. Ian Brooke explained that if the material will be used in the sea, that environment is an ideal test case, and that salt spray testing is often used as a benchmark for relative corrosion resistance because salt provides conductivity in the electrolyte and helps drive corrosion. He also noted that corrosion behavior depends strongly on the actual service environment. In a follow-up, Ted clarified that the likely reference was the neutral salt spray test, an accelerated corrosion test run in an ASTM B117 chamber. He said it is widely used largely because it is well known and accepted, while other accelerated tests such as CASS and Corrodkote also exist.
Q. Sir,
I understand that the best way to test the corrosion property of a material is by studying it under sea water (3.5% NaCl). Why is this method most suitable though it is a neutral salt solution?
Dr.Gayathri srinivasan
SSN College of engineering – Chennai, Tamil Nadu, India
2003
A. If you’re planning to use the material under the sea, then that would be an ideal way of testing it. I do suspect you are referring to a Salt Spray Test, where the material is kept in a warm moist salt laden atmosphere. Which is a common corrosion test. It is often used as a benchmark for relative corrosion resistance. Salt is used to provide a good level of conductivity in the electrolyte, which aids the process of corrosion. It should be borne in mind that corrosion behavior is highly related to the environment and conditions of use.
Ian Brooke
university – Glasgow, Scotland
2003
Q. Hello TED,
I have been waiting for the reply. Kindly let me know the fate of my query.
Dr.V.S.GAYATHRI
– CHENNAI, India
2003
Your inquiry was answered quite a while ago, Dr. Gayathri. Implied in the answer was a request for clarification. People don’t like to misunderstand a question and then prattle on, because the effort they put into their reply may be wasted.
But assuming again that you are asking about the neutral salt spray test, it is an accelerated corrosion test conducted in a test chamber built and operated according toASTM B117. It is widely used because it is widely used. That is, it may not be a great test but it is a well-known and well-accepted one. There are many other accelerated tests including CASS, Corrodkote, etc.
Good luck.
Ted Mooney, P.E.
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