Mechanical Engineering - Workshop Technology - Discussion

Soldering= Flux is zinc chloride, ammonium chloride.
Brazing = Flux is borax,
Braze welding = Flux is borax.

BRAZING:

Filler material - Cu& zinc, cu & silver, cu & alu.
Flux - Borex.

SOLDERING:

Flux - zinc chloride and aluminium chloride.
Filler material - tin & lead base alloy.

Yes, a fluxing agent is required for all brazing and soldering applications. The purpose of the flux is to remove oxides from the base material and to prevent oxidation during the heating process, thus promoting the free flow of the brazing filler metal. Unless brazing operations are contained within an inert or reducing atmosphere environment (i.e A vacuum furnace), a flux such as borax is required to prevent oxides from forming while the metal is heated.

Why only borax?

Why is borax?