Summary for black electroless nickel darkening Discussion
Black electroless nickel darkening is the focus keyphrase here, and the thread explains that the color variation is not simply a direct, predictable result of phosphorus percentage alone. The questioner, K. Bodily, describes steel panels with a 120-grit grain that are EN plated and then oxidized, but the finish ranges from bright silver to dark bronze, with only occasional true black. The concern is whether a mid-phosphorus bath’s 5% to 9% phosphorus range could explain the inconsistency. The excerpt does not include any replies, so no named answerer offers a mechanism or corrective advice. The practical takeaway from the question itself is that the process appears highly variable and the color outcome is not being held consistently from plater to plater, suggesting other process factors besides phosphorus content are likely involved.
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Q. Hello,
I have an extensive background with anodizing (Al & Ti) and I can carry a conversation with some electro plating processes, but I haven’t much experience with Black Electroless Nickel with a mid-phosphorus and am asking the community for some insight.
We have steel panels with a 120-grit grain on them and have them EN plated. The panels then go into an oxidizer that turns them darker. I won’t say black here because we are getting a range of colors from our plater that go anywhere from a bright silver (very little darkening) to a dark bronze color. Sometimes we will get something that could be considered black, but most of the time we get a bronzy/charcoal color.
I am trying to understand the mechanism that is creating the black color. I have been told that the darkness is a function of the amount of phosphorus in the nickel bath and that having more phosphorus would lead to a lighter panel, having less would create a darker panel. I’m not sure if this is the case (it’s just what I’ve been told), but if it is and a mid-phosphorus bath could be anywhere from 5%-9% phosphorus, then there would (could be) quite a range of colors produced since going from 5% to 9% phosphorus is nearly doubling its concentration.
What exactly is going on in this process that is creating the black color?
Why do we see such a large amount of variation in color?
Supposing the color is from the phosphorus concentration, and it could be 5%-9% how in the world could 2 different platers on opposite sides of the world ever obtain the same color consistently?
Thanks
K. Bodily
– Gardnerville, Nevada
May 29, 2024