Where the
world gathers for metal finishing
Q&As since 1989


-----

Why does the hard chrome on nickel fail

 

I am plating hard chrome over Nickel substrate. The product is used in a hot, acidic ( not so much, about 5.5 pH )aquaeous atmosphere. We have received complaints from clients that some times the product fails prematurely. From the inspection of the failed product, it is seen that the chrome has come off at places completely where as at other places, the chrome is as good as new.

After asking a few questions around, few theories have come up. 1. It is the battery action between nickel and chrome that has caused this. (due to aquaeous acidic nature of enviro ) 2. The adhesion is poor.

We are using the present hardchrome chemistry for the last 3 years and we have never faced any problems of this sort. We were using fluoride based chemistry before that without any problem. The precleaning and activation cycles have been looked into and they have no problems. My question is Usually hard chrome is used for wear protection in a oil or grease based atmosphere. Since ours is water based, is corrosion or erosion the prime culprit? There are sulphate based, fluoride based, organic additive based hard chrome baths. which of the above is better suited when corrosion by battery action is the prime culprit.

Nitin Kibe
- Pune, India