RE: [CR]Silver Solder vs. Silver Braze

(Example: Component Manufacturers:Avocet)

From: "Mark Bulgier" <mark@bulgier.net>
To: classicrendezvous@bikelist.org
Subject: RE: [CR]Silver Solder vs. Silver Braze
Date: Tue, 27 Aug 2002 02:43:12 -0700


Brian wrote
> That would be silver braze. Soldering is for electronics.

and Ed Kasper replied
> Please explain the difference...

I've heard the difference described as the song goes: Is it a question of love? Hah! Is it a state of mind? no no no no! It's a question of... It's a question of... It's a question of... Of temperature - yeah. (http://bulgier.net/mp3s/BalloonFarm-AQuestionOfTemperature.mp3)

...with soldering being defined as under a certain temperature and brazing over that temp. The temp in question isn't arbitrary, it's pegged at where a qualitative change in the bond occurs. I ain't no metallurgist, but I think a solder is something like a mechanical-only joint, like glue. A braze is stronger because there is alloying going on - the filler and parent metal interpenetrate.

I also know that brass inclusions in the steel (maybe silver too?), and intermetallic compounds, are very bad things that occur when the braze is way too hot, and cause brittleness. So I guess a little interpenetrating is a good thing but too much is bad? This is where my rudimentary materials science knowledge leaves off.

There are silver-bearing fillers that melt in the soldering range; others melt in the brazing range. So which you're doing depends on what filler you're using. Soldering isn't strong enough for bike frames, but it is for plumbing.

Mark Bulgier
Seattle, Wa
USA