[TowerTalk] Al-to-Al

Fri Feb 16 10:42:52 EST 2018

Conductors (at least metals) are rated on an electromotive scale.  The 
farther apart they are on the scale the greater the voltage generated 
when an electrolyte is present. Stick a piece of aluminum into a lemon 
(citric acid solution for electrolyte) and also stick in a piece of 
copper and touch the two metals with your multimeter probes and note the 
voltage.  Switch over to current measurement and see the short circuit 
current the little battery will produce.

When dissimilar metals (different ratings on the electromotive scale) 
touch in the presence of an electrolyte (acid rain, salty ocean breeze, 
etc current flows and the less noble metal is eaten away by  
electrolysis (AKA electrolytic corrosion.)

Zinc particles in an oil or grease base are protected from contact with 
an electrolyte. When a joint has Penetrox or other equivalent zinc 
particle bearing paste in it and is tightened the zinc particles are in 
contact with the two substrate materials to be joined, promoting good 
conductance and are protected from galvanic action by the oil/grease.  
By itself zinc is not magic and will corrode easily.  You wouldn't want 
to use zinc washers in place of the zinc particle loaded paste.

Replaceable pieces of zinc are used on prop shafts and propellors to 
protect the shaft and prop from damage by electrolysis. The zinc is 
considered a "sacrificial element" as it is eaten away by electrolysis 
while protecting the prop and shaft. Many of the 6 gal water heaters 
found on RVs have replaceable sacrificial zinc rods in them. In that 
service corrosion of the replaceable zinc is intentional to protect 
other components.  In joining aluminum antenna components you don't want 
corrosion and the zinc in the paste is not intended to be sacrificed to 
protect the aluminum.

Anyone want to design sacrificial zincs to put on antennas?

Patrick        NJ5G

On 2/15/2018 9:52 PM, Kim Elmore wrote:
>  From this thread, I learned that stainless steel and aluminum are a corrosive combination. I hadn’t heard this before.
>
> I’ve known that copper and aluminum are a corrosive combination and so the Jet Lube SS-30 surprises me. But I also wonder about zinc (the main component of NoAlOx, OxGard, and Penetrox) and aluminum. Is that truly a combination that plays well together?
>
> Kim N5OP
>
> "People that make music together cannot be enemies, at least as long as the music lasts." -- Paul Hindemith
>
>> On Feb 15, 2018, at 18:44, Kim Elmore <cw_de_n5op at sbcglobal.net> wrote:
>>
>> I asked the question to make sure something was needed for Al-to-Al and it seems it is truly is. Long ago, I was told that Al-to-Al was best dry because galvanic corrosion couldn’t
>>
>> When I was In CO, I used some stuff called OxGard because it was supplied with an antenna. It seemed to work well there, but CO is very dry. OxGard has a petroleum grease containing graphic and zinc particles. After about 10 y in CO, everything seemed fine and when I took the antennas apart to move to OK, the grease was still greasy. I used it when I reassembled the antennas here. But, I always wondered if the stuff was truly necessary.
>>
>> Kim N5OP
>>
>> "People that make music together cannot be enemies, at least as long as the music lasts." -- Paul Hindemith
>>
>>> On Feb 15, 2018, at 16:45, Keith Dutson <kdutson at sbcglobal.net> wrote:
>>>
>>> May have something to do with weather conditions.  I noticed Penetrox seems to dry out quicker here.
>>>
>>> -----Original Message-----
>>> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Bill M
>>> Sent: Thursday, February 15, 2018 4:24 PM
>>> Cc: towertalk at contesting.com
>>> Subject: Re: [TowerTalk] Al-to-Al
>>>
>>> We found when we took older antennas down where Penetrox was used were corroded together or extremely hard to separate. We went to Noalux 30 years ago and haven’t looked back.
>>> Bill W2CQ
>>>
>>>> On Feb 15, 2018, at 9:05 AM, Keith Dutson <kdutson at sbcglobal.net> wrote:
>>>>
>>>> Cannot find Noalox here in these stores in Houston.  Penetrox is available, and I keep a supply in the shack for general use.  Seems to be pretty much identical to Noalox for my use.
>>>>
>>>> 73, Keith NM5G
>>>>
>>>> -----Original Message-----
>>>> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of john at kk9a.com
>>>> Sent: Thursday, February 15, 2018 7:17 AM
>>>> To: towertalk at contesting.com
>>>> Subject: Re: [TowerTalk] Al-to-Al
>>>>
>>>> Noalox seems to be more available at the big box stores, I wonder why Penetrox became popular with amateur antenna builders.
>>>>
>>>> John KK9A
>>>>
>>>>
>>>> To:    towertalk at contesting.com
>>>> Subject:    Re: [TowerTalk] Al-to-Al
>>>> Date:    Wed, 14 Feb 2018 16:09:29 -0500
>>>>
>>>> We’ve tried pretty much everything in our salt air environment of South Florida. Most here use Noalux successfully over the past 30+ years.
>>>> Bill W2CQ
>>>>
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