51095

E-Nickel Plating for pump cylinder; thermal cycling  

January 29, 2009

I have a small pump bore (12.7mm) in 6061-T6 Aluminum. The piston seal is Teflon. I need to E-Nickel the bore for the seal performance. My pump will be operating between 20C and 115C, so I am concerned about the Nickel flaking.

I have read articles here about E-Ni on Aluminum operating over 200C. I would like to know if anyone has experience with specific E-Ni performing better or worse with temperatures between 20C and 115C and if thermal cycling can lead to flaking.

As a side note, I found out the expensive way that hard anodizing does not like to see 75C. My pump components' surfaces all cracked. After the fact I read a few articles here discussing this.

Thank you in advance.

Lansing Stout
Designer - Corvallis, Oregon, USA

I rather doubt that it is the temperature that is bothering your hard anodizing, since pots that are hard anodized go over 100C and frying pans will sometimes go over 200C.
I think that there was something is the liquid that was pumped that caused the problem like bleach, some soaps that are slightly alkaline and who knows.
If you do a proper EN on aluminum cycle, you will not have flaking. You can do a 400F for 4 hours heat treat that will show up any blisters as well as harden the nickel.

James Watts
- FL