×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Corrosion Inhibitor for Solder in Heat Transfer Solution?

Corrosion Inhibitor for Solder in Heat Transfer Solution?

Corrosion Inhibitor for Solder in Heat Transfer Solution?

(OP)
Could anyone tell me a corrosion inhibitor for solder for use in a heat transfer system that is nitrite, amine, phosphate, borate and silicate free?

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

If it is the solder being corroded can you use a different solder?   

Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com
 

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

What is the heat transfer fluid?

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

(OP)
Thanks for the responses, Im afraid the solder is non-negotiable, the solder type is ASTM Alloy Grade 30A (SAE 3A). I am working on finding the exact make up of the solder which I will post as soon as I can.

The heat transfer fluid is water with a 5% organic acids as corrosion inhibitors. However they have performed poorly versus only the solder.

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

(OP)
Make up of the solder is as follows:

Tin 29.5-31.5%
Lead 67.5-69.5%
+ traces of Sb, Ag, Cu, Cd, Al. Bi, As, Fe and Zn

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

Here is what I get.  You are starting with plain water from some source.   If you use it as is you get scaling.  If you add 5% organic acids you get corrosion (the lead dissolves?)

Have you tried a search for non-corroding water?

Your key might lie in control of the Saturation Index.  
 
For solders I think I would start with Lucas Milhaupt 800 558-7006.

Were it my project I would look at automobile coolants and anti-freezes to start.   You might be able to use something off the shelf.   

tom  
 

Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com
 

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

(OP)


I am actually working in the automobile coolants buisness, as part of the procedure for developing new products we need to ensure that they do not corrode a selection of metals. The coolant I am working on performs well against everything but the solder. I'm afraid I cant simply go and buy an off the shelf product as I am trying to develop a rival to said products. We have to use corrosive water (water with added sulfate, chloride and carbonate ions) for this specific test. As you say it is probably the lead that is the issue so I need to find an inhibitor for it. I can find plenty of inhibitors but none that are free from nitrite amine etc.  

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

Try searching for "inhibiting nitrite amine corrosion of lead" in Yahoo and Google.    Looks like some good info.  

Also try "inhibiting solder corrosion"

From the way you describe it, it sounds like you are really close on a good product.   Good Luck.

Also try the solder people.

Tom
 

Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.    

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

Can you comeback with what the acids are?

Acids like acetic would be very bad.

I've used certain organic acids to dissolve Pb in one of our processes.  

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

(OP)
The acid of question is 2-ethyl hexanoic acid, however it is reacted with a base (potassium hydroxide) to for a potassium salt, so there shouldnt be much free acid in the heat transfer system.

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

The only use I've seen of this acid is as a salt of heavy metals. The most prevalent one is the Calcium Barium salt used as a stabilizer for plastic manufacturing. We used it a as Cadmium salt for several years. I would suspect that there is enough ionization that you are getting acid attack on the lead.
This is pure "Edisonian",I would try a phosphomolybdate as a starting point since you have excluded the normal array of corrosion inhibitors. The molybdates are quite common as inhibitors in cooling water systems.

I have no information as to the stability of your salt but based on other fatty acids it probably has some very defined temperature limitations.  

Another is to try the Calcium salt in place of the potassium salt.   

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

(OP)
Thanks for the responses, I have undergone a new set of corrosion tests using an addition of sodium molybdate to see how that effects my results.

As for using Calcium Hydroxide I think that is a no-go looking at the Health Risks of using it on an industrial scale.  

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

I would recheck your information on Calcium Hydroxide as to health or disposal risks. Lime water is used in food products and myriad of other things that are in contact with people and the environment.

I would look at the molybdates used in CTW systems as there are quite a number of formulations. We used several different formulations in our water systems until we got one with acceptable results.
 

RE: Corrosion Inhibitor for Solder in Heat Transfer Solution?

(OP)
In case anyone is interested and for sake of completeness the addition of Sodium Molydbate at approximately 0.1% concentration did the trick, eliminating the solder corrosion.

Thanks for the responses appreciate it

lighterthief  

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources