brazing?

Lead is called soldering....

"Clif Holland" wrote: Lead is called soldering.... ^^^^^^^^^^^^^^^ That is the first thought that crossed my mind, but I think there must be something about the tin in solder that makes it flow and wet better.

Surface tension and solubility. The characteristic of brazing (as distinct from bronze welding) is that the filler material "wets" the base metal and flows by capillary action alone. For welding or soldering you have to poke it into place mechanically. Welding differs from soldering (and brazing) in that there's significant diffusion between the weld and the filler.

Silver is used rather than brass to lower the melting point. You might also find it interesting to look up "eutectic" behaviour in alloys.

I suppose the number of free electrons has bonding actions. Cu and Ag are in the same outer shell column of the chart - Zinc next to Cu. Cd next to Ag.

Near the full outer shell columns lie Tin and Lead. I think to many electrons to match up with a half shell (using rough numbers in the election counts) for Fe.

So I would think it is atomic bonding issue. Heat opens up the shells for play with the other metals.

Martin

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Grant Erw> What is it about silver or brass that makes it acceptable brazing rod?

Generally the difference between brazing and soldering is defined by temperature. Soldering according to one of my old texts is limited to 300 to 500 degrees F. Some define brazing as temps over 475. You can weld lead pipe with lead. It really is all relative. I have lead soldered steel together with varying results. If you are careful and clean your joints lead base solders will bond to steel. My first attempt was as a slot car enthusiast. I made my frame out of spring wire while everyone else around me was using brass. My car was light and had amazing acceleration. Randy

GWE