Metal finishing Q&As since 1989

-----

Electroless Nickel Plated carbon tool steel: need improvement in corrosion

August 24, 2009

Hello,

I'm looking for help with an application.

Trying to cure a corrosion problem with Electroless Nickel plated carbon steel (5-10µm plating).

Food production area (not direct food contact) washed down with water and detergent (awaiting exact details on the detergent).

There is a bolt tightend against the plated surface.
So need some scratch resistance.

Material:
Heat treated (after forming) SK5 (JIS carbon tool steel)Equivalents for reference are: AISI 1086, DIN C85S/CK85(C85E), NF C90.

304 Stainless stands up well to environment but is too weak.

Do you have an opinion on the best surface treatment.

Currently looking at:
Raydent (seems to be cryogenic diffusion?) and can't find info of supplier outside of Japan.
Thicker Electroless Nickel plating ?µm
Any others you know of?

Robin White
automation - Bletchley, Buckinghamshire, UK

---

First of two simultaneous responses -- August 27, 2009

5-10 micron will give you no corrosion resistance
You need 25 microns at least.
But that is not all.
You asked for wear resistanc which means that you need a low phos electroless nickel.
BUT, a low phos EN has no good corrosion resstance.
So, you need a layer of Mid phos EN for the corrosion resistance and on top of it a low phos layer for the wear resistance.
This is not the end of the story. You have to check the local regulations for coating approved for food ultilities.

Sara Michaeli
Tel-Aviv-Yafo, Israel

---

Second of two simultaneous responses --

Robin,

A couple of things strike me. First of all you do not state what type of electroless nickel. For corrosion resistance you need to use a high phosphorus process. Secondly your thickness seems too low. I would suggest a thickness of at least 25 microns.

Brian Terry
Aerospace - Yeovil, Somerset, UK
August 27, 2009

---

September 15, 2009

Thank you both for your replies, I had thought perhaps its too thin a coating. I have now read on high phos. option and need to investigate its suitability to food area use.

Would like to thank all involved with this website.

Its good to talk.

Robin White'
- Bucks, UK