The Brazing Reaction of Iron Base Metal with Copper. I : On the Dissolution of Solid Iron into Molten Copper

A basic investigation in brazing was undertaken to study the dissolution of iron base metal in molten copper. The cylinders of iron material were immersed in molten copper and then rotated under dynamic conditions of peripheral velocities from 18.3 to 58.6cm/sec at the temperature range 1200°～1400℃, the exposure time being from 40 to 480sec. The rapid dissolving of the base metal in molten copper occurred and excess dissolved base metal was crystallized within the copper and on the iron-copper interface during solidification. The rate of dissolution of solid iron in molten copper increased with increasing temperature and rotational speed. A modified first-order kinetic equation based on a mass was used to determine the solution-rate constants. These varied from 0.68 to 2.90×10^ cm/sec depending on the temperature and the rotational speed, and were increased in proportion to 0.60～0.71 power of peripheral velocity. The activation energy for dissolution of solid iron in molten copper was estimated to be about 15.3 kcal/mole. The dependences of the solution rate constant on temperature and peripheral velocity and of initial solution rate (the obtained value ranged from 2.88×10^ to 3.70×10^ g/cm^2-sec) on temperature led to the following results : the dissolution of solid iron in molten copper is diffusion-controlled, but at higher temperatures and higher velocities there is a change in the behaviour of the dissolution