錫箔上における水銀の表面擴散及び通電擴散

Abstract

In this studiy two groups of tin foils reduced from 2 mm to 7μ in thickness were used. One group A was treated with benzol and ether, the othes group B benzol, slightly etched by HCl dil., and subsequently washed in the order of water, alcohol and ether. As more than 2 days passed between rolling and surface treatment, X-ray Laue photograph of tin foil showed that both samples had already been recrystallised. Tin foil was hung down on mercury kept in a dish, and measurements were held in electric-thermostatt. From Fick's differential equation of diffusion, using proper boundary conditions of surface diffusion, we obtain D=y2/t, ･D is surface diffusion constant, y diffusion distance and t time. We can easily discriminate between diffused surface and original tin surface. Diffusion constants are as follows:[Table omitted] Thus we obtained DA=0.1516 exp (-3450/RT), DB=-1.148 exp (-5180/RT). We applied direct current to surface diffusion by hanging down two tin foils on one dish filled with mercury and made a circuit with battery. In this case, we found that movement of mercury atoms, i.e. acceleration or retardation of diffusion velocity at electrode, can easily be determined in a short time in comparison with ordinary electrolysis. At 12℃, under the condition of 6V-6A, and diffusion velocity of mercury were accelarated at anode. But the diffusion velocity at each electrodes is larger than in the case of no current, because of temperature elevation due to Joule's heat. X-ray photograph by back reflection of diffused surface shows that amalgam is hexagonal system (Hg 6-10%).