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Nickel Electroforms are magnetic
Q. Hello all,
I use the nickel electroforming process to create optical reflectors for the projection market. I am using nickel S-Rounds, run a nickel concentration around 80g/l, boric 40 g/l, pH 3.8, surface tension 45 dyn/cm, and plate near 150 A/sf.
I noticed my reflectors have a slight magnetism to them. I use arc lamps in the reflector module. I can change the arc path slightly by passing another reflector behind the module. I cannot detect the presence of the magnetic field in any other way except in the deflection of the arc.
Has anyone experienced the same?
Best regards,
Christopher Jensenlaboratories - Bohemia, New York, USA
2004
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A. Nickel is naturally magnetic.  Trevor Crichton R&D practical scientist Chesham, Bucks, UK 2004 A. Since nickel (and cobalt for that matter) is ferromagnetic, so should the nickel plate be ferromagnetic.  Bill Reynolds [deceased] consultant metallurgist - Ballarat, Victoria, Australia We sadly relate the news that Bill passed away on Jan. 29, 2010. 2004 |
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Q. Since my last post I have borrowed a gauss meter. The portion of the reflector that is closest to the arc shows the largest magnetism. At first I thought the magnetic field could have been created by the arc, a cooling fan, or the igniting voltage. I have run an experiment and have determined that the problem is in the electroforming process. The reflector has two geometrical axes of symmetry. No symmetry has been observed in the resulting magnetic field. Any comments? By the way, Nickel is naturally magnetic not a magnet. In short it can be affected by a field but does not (or at least should not) produce its own field. Best regards, Christopher Jensen [returning]- Bohemia, New York 2004 A. High phosphorus electroless nickel is non magnetic, and has good reflective properties. Consider electroless forming.  Don Baudrand Consultant - Poulsbo, Washington (Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links] and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links]) 2004 |
A. Neither Trevor nor myself was suggesting that nickel is a magnet, only that it is ferromagnetic (i.e., attracted to a magnet similarly to the way iron is attracted). Problems from informal use of the term "magnetic"!
If you have a nearby electrical current (arc lamp?), that arc or plasma will be surrounded by a magnetic field created by its current. This field will be picked up and concentrated by the nickel which will become a magnet while under the influence of the external field. The arc plasma is then a current subjected to an external magnetic field and will thus experience a mechanical force whose direction depends on the directions of the current and the field. This is what you are seeing, if I interpret your descriptions correctly.
Sounds as though you need a non-ferromagnetic reflector, perhaps in line with Don Baudrand's suggestion.
Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
2004
Q. Why is nickel magnetic?
Tony Trevino- Baytown, Texas, US
2006
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