I am familiar with Alodine. It was used by the 100s of gallons of the liquid
version to passivate the aluminum in the products produced by my former employer.
We also had the facilities to do this and other plating in our engineering
shop. You can see some of my personal handiwork here: http://sadxa.org/n7ws.html
I can tell you that the "conductive" version isn't at 10 GHz. The prototype
Phoenix missile solid-state amplifier that I was responsible for getting from
prototype to production used an aluminum cavity with sixteen IMPATT diodes
arrayed radially around the cavity. The cavity was machined into one piece of
passivated aluminum that was closed with another. The power out and tuning was
very erratic and could be changed by separating the parts, cleaning the surfaces
with swabs and alcohol and reassembling them. We finally gave up and went to
gold plating. Problem solved.
This is far enough OT that I won't elaborate on another example where gold
plating can get you in trouble.
On 10/12/2016 3:51 AM, David Cutter wrote:
A quick note on a protective coating for aluminium:
You might like to look at Alocrom 1200 (Alodine 1200 outside Europe) which can
be hand-applied to preserve and protect aluminium from corrosion, retaining
its conductivity. I used it for many years in industrial and military
applications, where it is applied more thickly but for our purposes it
produces a pleasant gold colour. You can mix small amounts for small areas
that need protection. Surfaces need to be scrupulously clean first.
Over here a 1kg kit can be purchased for around £40 including delivery.
Here's the instruction leaflet:
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