ロウの拡がりにおよぼす溶剤の基礎的性質に関する研究(第 1 報) : 溶剤の粘性

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The most widely held view on the flux action with soldering and brazing is presented by three principal functions which are described below. 1. To dissolve or releasen any oxides present on the base metal and molten filler alloy surfaces which are to be brazed. 2. To prevent the oxidation of these surfaces during the brazing process. 3. To lower the surface tension of the molten filler alloy, namely, the molten flux should be readily displaced by the molten filler alloy, thus promoting the wetting of the base metal by the molten filler alloy. The last of the above mentioned functions belongs to the physical meaning of the flux action and, accordingly the investigation of the viscosity of flux saturated with metal oxides is one of the most important for gaining a thorough knowledge of the brazing phenomena. In this paper, the relation between the viscosity of the molten flux and the interfacial tension between the filler alloy and the molten flux can not be reported but the paper describes the variation of viscosity with various fluxes which were heated to either the lower or the higher brazing temperature in a porcelain or graphite crusible. The results obtained from the investigation are as follows : 1. By small additions of powder ammonium chloride or granular stannous chloride, or both of them to the molten zinc chloride, the viscosity can considerably be decreased. In the binary molten flux system, the minimum value (about 1.5 poise at 450℃) of the viscosity was recognized when using the 75% ZnCl_2-25% NH_4Cl, the 70% ZnCl_2-30% SnCl_2・2H_2O. On the other hand, the maximum value (about 2 poise at 300℃) was found when using the 50% ZnCl_2-50% SnCl_2・2H_2O. 2. The viscosity of either the eutectic composition or compound in the ZnCl_2-NH_4Cl system seems to indicate the minimum value, as well as the fluidity of the molten metal and alloy in cast processing; for instance, if the relation between fluidity and viscosity is shown reversibly under physical considerations, the antimony-lead alloy or the antimony-cadmium alloyhas the same phenomena. 3. Boric acid (about 80 poise at 900℃) has a higher viscosity than borax (about 10 poise at 900℃) and the viscosity decreases as the borax in the mixtures is increased. But it should be noted that the transition point (at about 780℃) was observed when producing the phase change which would be probably considered as the chemical reaction : 2H_3BO_3=B_2O_3+3H_2O in mixed system. Further research is needed to understand this "transition point."
社団法人溶接学会の論文
1963-08-25

ロウの拡がりにおよぼす溶剤の基礎的性質に関する研究(第 1 報) : 溶剤の粘性

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