Rates of dissolution of rotating iron cylinders in liquid copper and cu-fe alloys

Iron cylinders with molybdenum capped ends are rotated at speeds of 260, 570, and 835 rpm in liquid copper and Cu-Fe alloys maintained at 1220°, 1300°C, and 1370°C under argon at 1 atm pressure. The dependence of the dissolution rate of the cylinders on the concentration of iron in the bulk liquid is observed. The solution-rate constants defined by an approximate form of the Berthoud equation vary from 7 × 10^-3 to 30 × 10^-3 cm.s^-1. There is a linear relation between the logarithm of the rate constant and the reciprocal of absolute temperature for each rotational speed. The rate constant is found to vary with the 0.85 to the 0.96 power of the Reynolds number in the range 6500 〈 Re 〈 22000. This suggests that the dissolution process is diffusion controlled. The dependence of the dissolution rate on the activity of iron in the bulk liquid is observed. Oxygen increases markedly the dissolution rate, whereas sulfur does not.