Gaseous Shielding Gas Additives as Flux Substitute for TIG Arc Brazing

Abstract

Brazing is one of the key technologies in the field of joining of metal components. To improve the wetting of brazing material and work-piece surface, it is often required to fall back on the use of flux. The application of these substances requires accuracy and is often connected with considerable expenditure and it is, just as the removal of flux residues, often an additional working step which has to be carried out manually. Within the framework of a DFG research project it has been investigated to which degree gaseous substances as addition to the shielding gas may replace conventional flux in TIG arc brazing. To this end, investigations have been carried out using different combinations of base and filler materials. Mainly monosilane as a gaseous flux substitute has been added in low concentrations to the shielding gas volume flow. The resulting brazed joints have been quantified with regard to their geometry, their fusion conditions and their chemical compositions. These qualities were then correlated and evaluated with the provided quantity of monosilane in order to identify dependencies.

Oxygen‐Free Production—From Vision to Application

“…[11,12,75] Processes can be separated into furnace processes in silane-doped atmosphere [12] or silane addition to a shielding gas flow. [11] Reisgen et al correlated monosilane addition during TIG arc brazing with shielding gas to properties of the brazed joints. They observed a decrease of the wetting angle of CuAl7 on S235JR to 36°with increasing silane addition to the shielding gas flow up to 0.6 L min À1 of 1% silane in argon.…”

“…[ 11,12,75 ] Processes can be separated into furnace processes in silane‐doped atmosphere [ 12 ] or silane addition to a shielding gas flow. [ 11 ]…”

“…Several researchers describe adding monosilane to the atmospheres used in high-temperature brazing processes in order to improve brazed joint quality. [11,12,75] Processes can be separated into furnace processes in silane-doped atmosphere [12] or silane addition to a shielding gas flow. [11] Reisgen et al correlated monosilane addition during TIG arc brazing with shielding gas to properties of the brazed joints.…”

“…One promising approach to generating a practically oxygen-free environment at ambient pressure at low cost is the addition of small amounts of monosilane (SiH 4 , hereinafter referred to as "silane") to inert gas atmospheres (argon, nitrogen, or, for special applications, helium). [11,12] By adding monosilane, the residual oxygen content present in the DOI: 10.1002/adem.202201819…”

“…One promising approach to generating a practically oxygen‐free environment at ambient pressure at low cost is the addition of small amounts of monosilane (SiH 4 , hereinafter referred to as “silane”) to inert gas atmospheres (argon, nitrogen, or, for special applications, helium). [ 11,12 ] By adding monosilane, the residual oxygen content present in the inert gas atmosphere (usually <20 ppmv) is completely removed by conversion to SiO 2 , H 2 , and H 2 O. Since the silane concentration only needs to be as high as the concentration of residual oxygen in the inert gas, even very small amounts of silane are sufficient.…”