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-----Expectations of Electroless Nickel.
1999
Hello people.
Is two to three hundred hours NSS resistance a reasonable expectation for an electroless nickel coating if:
- 1) the part has edges (stepped, even threaded, etc)
- 2) the part is sandblasted
- 3) light acid is used after the sand
- 4) the coating undergoes no subsequent heat treatment (so as not to harden it by crystallisation, either deliberately or inadvertently)
- 5) 25 microns of nickel is deposited ?
At this point, we are getting 5% corrosion within 24 hrs, which leads to intolerable corrosion by 48 or at best 72 hours. If electroless nickel cannot do this, can anyone suggest a coating which has a similar uniformity to e'less Ni, can get over 200 hours NSS, and preferably does protect sacrificially?
this is not easy: I'm a little stumped.
thanks in advance, Terry Roberts
- Australia
I would have expected a little more resistance from your EN, but EN does have pores in it and until you get to 0.0015" (1 1/2 mils) you will have attack thru the pores. Increase your thickness by 50% and your problem should go away.
James Watts- Navarre, Florida
1999
Terry, Been there - done that. The answer to all your questions is YES. But add the following: a) you are using a 12% + phosphorous bath b) you are using a 3% solution of chromic acid as a final rinse Ray
ray delorey- cambridge, ontario, canada
1999
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