MatSc503 Kinetics of Materials Processes Problem Set #5 Due April 5 1. Two similar carbon-saturated molten pig irons, one containing 0.8% S and the other 0.8% S and 0.46% Si, are in separate experiments put in contact with the same sulfur-free slag at 1500˚ C for desulfurization. The concentrations of sulfur in the metals at different times are as follows: It is obvious that the presence of Si enhances desulfurization kinetics. Determine whether this occurs because Si alters the order of reaction or simply because Si increases the specific rate constant of the desulfurization reaction. 2. When an iron-manganese alloy is induction melted under vacuum, manganese vaporized. The loss of manganese from the melt occurs by two steps: (i) mass transfer across a liquid boundary layer from the bulk of the melt to the melt surface, and (ii) evaporation from the free surface of the melt into vacuum. The kinetics of step (i) are given by J film = k 1 (C Mn bulk- C Mn s ) where k 1
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