Remember that when you look at a shiny piece of aluminum you are still
looking at a layer of oxide. Aluminum Oxide forms almost instantly and is a
means of protection. Out in the weather the oxide layer will thicken and
turn white. This is not harmful to the operation of the antenna either.
OTOH a layer of the thicker oxide makes the slip fit element connections
less conductive, BUT generally just sliding the elements togther will scrape
through the oxide layer is some spots. It's also the reason we use "star"
washers when making electrical connections to Aluminum.
> Aluminium WILL corrode in any environment, as will virtually any metal,
> except Gold, Platinum etc. Corrosion IS oxidation, that's the chemical
> process, which required Oxygen ( obviously) and moisture ( inevitable).
> Acidic and Chloride rich environments will exacerbate the process. If you
Aluminum is particularly reactive with basic solutions.
> check the dull surface, you will see white spots, and these are indeed
> Aluminium oxide. It is a significant problem only in terms of electrical
Not just the spots, the whole surface is a layer of oxide. They are usually
from water on the aluminum or water and salt solutions.
> continuity, so protect the joints between tubes as far as possible. As far
> as mechanical degradation is concerned, I am more worried about being hit
> by
> an alien spacecraft!
>
A conductive grease will protect the joint and the scraping of the element
going together will cut through the normal thin layer of oxide.
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com
> 73
>
> Clive
> GW3NJW
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com]On Behalf Of KT2Q
> Sent: 12 September 2005 06:13
> To: TowerTalk
> Subject: [TowerTalk] Aluminum longevity?
>
>
> All:
>
> Before I go to the trouble of coating the exterior of my new M2 Yagi, is
> aluminum corrosion a real problem with the alloys used today?
>
> Shouldn't the natural oxydation protect the surface of the antenna and
> stop
> corrosion? What about the inside of the elements and boom? If surface
> corrosion is a real problem, what's the sense of protecting the outside if
> the inside is left bare?
>
> I have a F12 antenna that's been up for 6 years. The aluminum is certainly
> dull, but I don't see any corrosion. The clamps are rusted to hell, but
> the
> rest is in fine shape.
>
> So, what's the average life expectancy of aluminum before corrosion takes
> it's toll and the antenna needs replacing?
>
> 73, Tony KT2Q
>
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
> any
> questions and ask for Sherman, W2FLA.
>
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>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
> any questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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