"jim rozen" wrote in message
...
snip--
sometimes by placing the entire item in a furnace with
a controlled (typically reducing) atmosphere. In the latter case
one can use things one does not typically think of as a braze material,
for example, gold, copper, nichrome. These can be applied in advance
to the joint as a preform (ring or sheet) or can be applied as
a paste of binder and metalic powder. Extremely intricate work
can be done this way. Bud was in charge of the hydrogen furnaces
and after he died things kind of were never the same. A real
craftsman.

About the time I left Sperry, they had started building a new product that
escapes me now. At any rate, it was furnace soldered. The most beautiful
of work. Perfect joints in every case. The item was made up of several
individual pieces, and I recall that the solder was pretty much copper
colored.

snip--

I found out how well lead can dissolve gold the hard way - by trying
to solder a 0.003 inch diameter gold wire with lead-tin solder.
Talk about frustration!

Jim

I imagine you've played with gold plated electrical pins in the course of
your hobby or work. Have you ever noticed that they are plated with nickel
before gold is applied? Sir T.K. Rose, in his Metallurgy of Gold,
documents the phenomenon whereby gold and silver, placed in intimate contact
with one another, will migrate from one to the other. Pins without the
nickel barrier slowly absorb the gold plating, leaving behind nothing more
than a copper or brass pin that has a miniscule amount of gold in its
makeup. Not enough to prevent corrosion. That happens at room temps.
No wonder heated lead is so aggressive.

Harold