Testing the Nickel Chrome plating Layers

A. Hi David. Please see our Introduction to Chrome Plating as the first step, which will help you understand the general ideas.

You have not introduced yourself yet, so when you ask how to check things, we don't know quite what you mean. Did your "customer" give you the parts because you specified them or bought them from them? Or are you a testing laboratory offering these services? The nickel plating layering can be checked, via the STEP test, for a proper potential difference to encourage the bright nickel layer to corrode to protect the semi-bright layer (you'll understand better after you read the Introduction). All chrome plating cracks, and the idea behind microporosity is to distribute the cracks so the electrochemical corrosion forces are distributed instead of being concentrated in small areas as well.

Please read the Introduction and get back to us with more detail. Thanks.

Regards,

Q. Hi Teddy, Sorry for that ... I am working as Manufacturing Head of an electroplaters shop in India. We bought our Customer parts from them to check the type of plating and its properties. Because previously they did some other suppliers. So that we bought from them to analyse it.

A. Hi again Sun David. I am not experienced in such analysis and we'll have to await further help from someone who is. But a metallographic cross section should reveal the multiple layers of nickel, as there will be a visible demarcation between semi-bright and bright nickel if it is duplex nickel, and you can estimate the thicknesses from a well done micrograph as well. You'll be able to see the chrome layer too -- but probably not the cracking pattern; for that I think you would need SEM work. Because of my own lack of experience with it, I don't know if it's possible to do a STEP test on the duplex nickel after chrome has already been applied.

If you are able to do CASS and/or Corrodkote testing on the purchased parts you should be able to come up with a plating sequence that will equal it. You may be able to get a head start in figuring out what kind of plating you have just from the application. For example, if the parts are for interior use they are probably single layer nickel. If the parts are high volume exterior parts, they are probably duplex (2-layers) nickel because less nickel thickness is required for quality plating with the duplex approach. If the parts are very low volume, they are possibly single layer even if intended for exterior use. Good luck.

Regards,