A very good customer has asked us to plate powdered iron parts with electroless nickel. We are aware that the parts must be sealed by impregnation but what else should we be aware of before taking on this project? G. L.
Plating of sintered metal powder parts is very much like trying to plate a sponge. The surface of the parts is very porous and if not plated with a heavy enough deposit, the pores will not be closed off. The trick is to make sure that the electroless nickel deposit plates the impregnated areas as well as the iron areas. To achieve this, the impregnated pores must be prepared to accept the electroless nickel.
One possible sequence for doing this is as follows:
The vendor of your electroless nickel plating chemistry should be able to help you obtain the proper sensitizer and activator.