Metal finishing Q&As since 1989

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Electroplating silicon dioxide

Dear Sir,

I'm PhD researcher, please I want help me by recommending a procedure for electroplating silicon dioxide over Zinc-nickel coating or used silicon dioxide in the same bath when electroplating Zn-Ni.

Rabea
Smart - Amman, Jordan
2006

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Silicon dioxide coatings can be obtained by evaporation in a vacuum system. A small amount of oxygen is also used (reactive evaporation) to get stoichiometric SiO2; otherwise, get SiO(2-x). Find someone nearby who does physical vapor deposition (PVD).

I am unaware of plating processes for SiO2. You can try a sol-gel process, but my experience is that many cracks form and adhesion is poor. Si can be deposited by decomposing silane gas (SiH4), a chemical vapor deposition process, and then the Si could be oxidized.

A polysiloxane coating is much easier and may be useful.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2006

Silicon dioxide is a molecule (neutral), not an ion. You can only electroplate electrically charged ions but not molecules which do not have an electrical charge. PVD processes, as suggested by Ken, impart a different kind of energy that propels the particles towards a target, so they are deposited onto a surface.

Guillermo Marrufo
Monterrey, NL, Mexico
2006

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As a PhD researcher you should understand the importance of clearly stating the question. The previous answers are correct - but again I would expect you to know that.
Although silica cannot be electrolytically deposited, it should be quite simple to co-deposit it. The process is commonly used to produce diamond grinding wheels, etc.
In simple terms, add silica to the plating bath and stir sufficiently to prevent it precipitating while plating. The plating thickness will need to be comparable to the particle size.
Alternatively put a layer of silica on the (horizontal) cathode, deposit through it and wash off the excess.

Geoff Smith
Hampshire, England
2006