溶融銅-銀, 銅-スズ系合金の活量について

Abstract

Activity of each component of liquid copper-silver and copper-tin alloys has been determined by applying the Knudsen effusion technique.Activities of copper-silver alloys show considerable positive deviations from Raoult's law, and agreed well with the data reported by the other investigators. The activity coefficient of silver at infinite dilution γ°KA g at 1, 100°C was estimated as 5.3. Entropies of mixing calculated from free energies of mixing and calorimetric heats of mixing fit well with the ideal entropies.Since the effused copper and tin were simultaneously condensed on the wall of silica condenser, respective amounts of these deposits were determined by the atomic absorption spectroscopy. Activities of copper-tin alloys determined satisfied the Gibbs-Duhem relation each other and show considerable negative deviations from Raoult's law. The value of γ°Ksn at 1130°C was estimated as low as 0.093. It was found that the order of activity curves of the alloys between copper and the metals belong to the fifth period such as silver, cadmium, indium, tin, and antimony was the same with one of the periodic chart.Difference between the behaviors of silver and tin in liquid copper, especially the posibility of the removal of these elements in the copper refining processes, was also discussed from the thermodynamic data obtained in the present investigations.