銀ろうの炭素鋼へのぬれ性について

抄録

The wettability of a silver brazing alloy (BAg-8; Ag-28 wt% Cu alloy) on carbon steel plates with different carbon contents were investigated in relation to the effect of brazing atmosphere. The wettability was examined by measuring the spreaded area of the silver brazing alloy on the base metal. Pure hydrogen and mixed gases of hydrogen and nitrogen in various composition were used for brazing atmosphere. The results obtained are summarized as follows:
(1) The spreading area of the silver brazing alloy on carbon steel tends to increase parabolically with heating time. The apparent activation energy for spreading of molten BAg-8 on the carbon steel was about 41.1 kcal/mol.
(2) The spreading area was affected by the content of hydrogen in brazing atmosphere, that is, the higher the content of hydrogen the better becomes the spreadability. The spreading area on the base metal of low carbon steel (0.1% C) in N₂-20 vol% H₂ atmosphere was approximately 50% of that in pure hydrogen.
(3) The spreading area varied with the carbon content in the base metal and decreased with increasing carbon content.
(4) The interfacial tension between molten BAg-8 and the mixed gases of hydrogen and nitrogen tends to decrease with increasing content of hydrogen. This shows that the better spreadability in the brazing atmosphere with higher content of hydrogen would be due to the effect of hydrogen which reduces not only base metal oxides but also interfacial tension.