溶融銅-ビスマス, 銅アンチモン系合金の活量について
溶融銅合金に関する熱力学的研究 (第2報)
1967 年 83 巻 948 号 p. 666-672
詳細
1967 年 83 巻 948 号 p. 666-672
Vapor pressures of bismuth and antimony have been measured for liquid bismuth, antimony, copper-bismuth and copper-antimony alloys respectively, in the temperature range from 900°C to 1, 200°C by the use of transportation method. The vapor pressure of each gaseous species, such as Bi, Bi2, Sb, Sb2, and Sb4, and total pressures were calculated from the available data on the equilibrium among these gas species of metals and the data obtained in the current work. The results shown below are agreed well with the values reported by the others:
logP (Bi+Bi2)(atm)=-8970/T+4.71 (900°-1200°)
logP (Sb+Sb2+Sb4)(atm)=-6030/T+2.99 (900°-1200°)
Activities of bismuth and antimony were calculated from the vapor pressures using the following relation
ai=(Pin/P°in) 1/n
where n is the number of atoms per molecule in vapor phase. On the other hand, the activity of copper were determined by the Gibbs-Duhem integration. For Cu-Bi system, the activity-composition curves show positive deviations from the Raoult's law. On the contrary, the activity of antimony shows a negative deviation especially in the copper rich side of Cu-Sb system. The maximum values of the heat of mixing were 1.5kcal/mole at NBi=0.52 for Cu-Bi system and-2.8kcal/mole at Nsb=0.26, near the composition corresponding to the intermetallic compounds, for Cu-Sb system.
In addition, the removal of bismuth and antimony from crude copper have been estimated from the activity coefficients of these elements in the infinite dilute solution, and the results indicate that the contents of bismuth and antimony in crude copper can not easily be reduced even by oxidation or vaporization.
