There are a few things you should consider.
The Galvanic Series https://en.wikipedia.org/wiki/Galvanic_series runs from the most "noble" metal to the best to use as a sacrificial anode in electrolytic corrosion. You will notice that copper is *above *aluminum and zinc is below aluminum. Thus, I am somewhat dubious about the use of copper-filled anti-seize in protecting aluminum elements in the outdoor environment subject to acid rain and bird guano (part of which becomes nitric and phosphoric acid under the effect of bacterial decomposition). It seems to me that zinc or magnesium would be better and that the copper anti-seize might be a good anti-seize but a bad sacrificial electrode. Zinc is readily available.
Steels are above copper on that table, and thus copper anti-seize is appropriate for that. Stainless steel has a potential for galling, so you need anti-seize with it. But you should be using it on _all_ fasteners. I can't over-emphasize what a pleasure it has been disassembling an antenna that spent 10 years in the air when the assembler used anti-seize diligently during its installation. I came with a hacksaw and bolt cutter, and never had to use them.
Stainless steel doesn't rust because it forms a protective layer of chromium oxide on its surface. It is this layer that can also form galling and seize the union of a nut and bolt. Aluminum also forms a layer of aluminum oxide very quickly when exposed to atmosphere, it is this that protects it from further corrosion.
We use rosin to remove these surface oxide layers from various materials and make them solderable. Rosin is an acid, but is only chemically active when heated, so it does not continue to rot the metal as other fluxes would. Because of the great speed with which these oxides form, welding of stainless steel and aluminum generally requires use of a gas which protects the joint from oxygen during the welding process.
On Sun, May 12, 2024 at 9:14 AM Jim S via AMSAT-BB amsat-bb@amsat.org wrote:
Sounds about right. However, I just tested some Permatex anti-seize and it reads in the few dozen ohms range when meter probes are even only 1/16 inch apart. So it is pretty conductive. As you point out when compressed it is certainly "conductive".
Jim -----Original Message----- From: Zach Metzinger zmetzing@pobox.com Sent: May 12, 2024 10:00 AM To: amsat-bb@amsat.org Subject: [AMSAT-BB] Re: Electrically conductive grease
On 5/10/24 11:16, samuel galet via AMSAT-BB wrote:
What is the best grease to use to lubricate aluminum antenna tubes to >
prevent corrosion and improve conductance. It also needs to conduct > electricity and protect metal screws from rusting.
The grease itself does not conduct (much). The joint pushes the grease out of the way and forms gas-tight metal-to-metal contact. The grease fills in the voids and prevents oxidation. I suspect there is a non-trivial amount of capacitive coupling going on, as well.
I use the cheap stuff, and it seems to work just fine. Find it at any big box store.
https://www.gardnerbender.com/en/p/OX-100B/Ox-Gard-Anti-Oxidant-Compound
73,
--- Zach N0ZGO
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