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BLACK CHROME PLATING PROBLEM
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Can any one help me on black chrome plating. Have tried following composition of the bath Cr2O3 (chrome anhydride) 250 gm/ltr Acetic acid 170 ml/ltr cd 150 asf The problems are: 1) Jet black colour not coming the colour obtained is metallic gray. 2) When attempting brown colour plating (with different cd value) with the solution the brown colour does not come uniformly there are gray patches at high cd areas raising of the temp helps but since acetic acid is not stable at high temp the plating stops taking place. Some one please help find solution to this problem or suggest some metal acetate which wont affect Cr plating and be stable at high temp. Thanks, Viney Chaddha- Gurgaon, Haryana, India |
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Are you plating black Chrome on bright Nickel or semi-bright (Sulphur free) Nickel ? Is your temp control uniform throughout the solution ? Are you oiling parts after plating ? Please post yr situation and maybe I can help.
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Khozema Vahanwala Saify Ind  Bangalore, Karnataka, India |
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Dear Khozema,
Thank you very much for the response I have tried this in a five litre beaker on a small plate the conditions are :
1) temp is uniform (room temp)
2) plating is attempted on bright nickel
3) there certainly no oil as the cleaning is as follows
a) ultra sonic
b) cathodic cleaning
4) any oil film present may be that of the brighteners and anti pit solutions used in bright nickel but the work piece is thoroughly rinsed after bright nickel
I would be extremely grateful if you can help
Thanks ,
Viney Chaddha- Gurgaon, Haryana, India
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Viney,
You must have a lower temperature 14-15 C degrees. I also suggest you to analyze the trivalent chrome maybe you have to much of hexavalent chrome in your black chrome solution. The ratio between anode and cathode is important 1:2 the anode area shall be more less than cathode area.
Regards,
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Anders Sundman surface finishing engineer Sweden |
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It is essential to not have any sulphate present. Add some barium carbonate to ensure no sulphate. Usually processes have other additives such as nitrate, fluoride, boric acid.
Geoff Whitelaw
- Port Melbourne, Victoria, Australia
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I wish You could talk on planet earth....apart from that the reason I was looking at this was because I am a designer in Spain and was looking up Black Chrome.............now I am confused...where can I get some good pics ? Chris Fletcherdesigner - Spain +++++++ Hi, Chris. It's a technical forum for solving plating problems and people asked the names of the chemicals. Are you suggesting we refuse to print them :-) Ask one of the suppliers of black chrome services or black chrome plating processes for pictures, but be aware that there are several different types for different purposes, including high absorptivity for solar collectors; non-reflective optical black chrome for microscope and telescope tubes; shiny decorative black chrome for auto parts, etc. Please tell us what you want to plate with black chrome and why. Good luck.
October 7, 2008 I am looking for a good formulation or bath composition for black chrome plating. Hope someone can help me thru this.. Macy Melgar- Makati City, Philippines ^- Privately contact this inquirer -^ January 12, 2010 Can you tell me ? How to make Black chrome surface finishing to have Black colour. What is factor? Prapha Phonsanstudent - Thailand January 12, 2010 Hi, Mark. Hello Prapha. Proprietary black chrome solutions are available from the international plating process suppliers like Atotech and MacDermid. That is the surest and fastest way. If you want to try to formulate the bath yourself, please phrase your questions in terms of the answers that are already provided rather than expecting someone to offer completely contrary advice :-) Regards,
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