The authoritative public forum
  for Metal Finishing since 1989
-----

Electroless plating on Stainless Steel

October 14, 2010

Hi everyone,

I have been trying to find information on the procedure to electroless plate MacDermid's Ni-PFTE electroless coating.

This is what I know,

Steps involved:
Alkaline clean
Rinse in DI water
Cathodic electro clean
Rinse in DI water
Woods strike
Electroless plating

What I don't understand:
What are the steps involved for the cathodic electro clean? basically how is this performed?
Why do I have to "activate" the stainless steel with HCl
I have found a lot of different information concerning the Woods Strike...
The most common formulation I have found is
120g/L Nickel chloride
10% vol. HCl
75-100 amp/ft2
3 min @ room temp

Any help would be extremely appreciated as my research does not involve the actual plating, I am testing the effect the plating has on processing equipment.

Thanks in advance!

Jay Bee
Grad student - Boston, Massachusetts, USA

---

Stainless steels can be electrolytically cleaned (cathodic electrocleaning - the job as cathode and platinum or graphite as anode) using an aqueous alkaline solution having a composition of 25 g/l Na2CO3, 35 g/l NaOH and 1 g/l sodium lauryl sulphate (sodium dodecyl sulphate) at 27 oC for 60 seconds.

The surface of stainless steel is covered with a naturally formed passive oxide layer. For electroless deposition, one of the important pre-requisites is the catalytic ability of the surface. Unlike low or medium carbon steel, stainless steels need to be activated. Deposition of a thin layer of nickel would make the surface catalytically active. Theoretically, any nickel containing solution can be used to achieve this. However, a Wood's nickel bath, which contains nickel chloride and hydrochloric acid, is commonly used to activate the surface of stainless steels, as this would also enable a better coating adhesion.

T.S.N. Sankara Narayanan
- Chennai, Tamilnadu, India
(ed.note: The good doctor offers a fascinating blog, "Advancement in Science" )
October 20, 2010