The authoritative public forum
  for Metal Finishing since 1989
-----

Anodization of aluminium for electrical insulation

Dear Finishing Fellow Members

I would like to know whether any process / related information / literature available for using anodized film of aluminium as electrical insulation film for the base metal (aluminium). Any detail would be of great help to me.

Dr. K. Murugan
corporate R&D. - India
1998

---

Dr. Murugan:

I can provide a little information, checking Resistivities in the CRC Handbook of Chemistry & Physics [adv: on Amazon & AbeBooks & eBay affil links] you find the following for aluminum 2.83 x 10EO-6 , and using the value of alumina as an approximation for the anodic coating 1x10EO11. So there is quite a difference, however if you look at the "dielectric strength for alumina it is low, 40 - 160 volts/mil as compared to polymeric materials. For instance polypropylene is 500 - 650 volts/mil.

Paul Stransky
- Putnam, Connecticut
1997

---

I am very interested in using the electrical insulating properties of the aluminum oxide coating (anodization) to fabricate insulated aluminum conductors in wire, strip and foil form. Thank You.

Ara Sayabalian
1998

Can you please give me suggestions on how to locate companies that sell aluminum anodization equipment. I tried via yahoo but was not really successful

Raed Shammas
Shammas Aluminium
1998

---

In our Directory of Equipment, you will find many manufacturers and distributors. Anodizing equipment is, for the most part, very similar to plating equipment and supplied by the same companies. So if you don't see any manufacturers of anodizing equipment in your area, just look for plating equipment.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
--

---

Does anyone know of an anodization process that is conductive and can be used for grounding an aluminum part? We are currently having to grind off areas to get a good ground. I know we can mask of the areas in the future, but was wondering if there was a better way.

Thanks for any and all help.

Wayne F Adolf
Aksys Ltd
1998

Anodic processes produce aluminum oxide which is non-conductive as you have found. Typically an area is masked off where a grounding connection is required, using inexpensive masking dots to protect the surface during anodizing. Conductive chem film is then applied. This prevents mother nature's natural aluminum oxide from forming on a fresh aluminum surface. If one grinds off an area for electrical connection without allowing for protection from the atmosphere, then over time the connection area will develop increasing resistance as an aluminum oxide layer is formed on the aluminum between the connection. This produces heat, as well as a poor connection at that area.

Ward Barcafer, CEF
aerospace - Wichita, Kansas
1998

Dear: Are there somebody who know how to control the thickness of anodized alumina film, and if there will be sth different between the anodization of aluminium and that of aluminium film deposited by some methods? thank you very much!

Chen Ying
- Beijing, P.R. China
2000

Could anyone help me by relating knowledge on how successful anodization is in practice as an electrical isolator? I am working on a project where electrical isolation is imperative for the functionality of the product. I would like any knowledge (bookwise or by experience) as to the effectiveness of anodization especially under manufacturing conditions. Thanx!

Sammye Miller
- San Jose, California
2000

Ed. note: The most complete compendium of aluminum anodizing information is Wernick, Pinner, & Sheasby's "Surface Treatment and Finishing of Aluminum and its Alloys".