Heat and mass transfer in solidification cladding.

The conditions under which solidification cladding can he carried out are considered, and the heat and mass transfer phenomena involved in the process are investigated. Most of the experiments involve the exposure of rotating cylindrical probes to liquid metal at various superheats as well as at zero superheat, and have been carried out using lead and tin and certain of their binary alloys. The initial chill-layer formed on the probe is remelted only in the presence of superheat. The melt back of the chill-layer is succeeded by dissolution of the probe surface. The rates of chill-layer growth and melt-back as well as the rate of surface dissolution have been determined experimentally for various degrees of superheat and probe rotation speeds. The problem has also been approached from the theoretical point of view by: 1. adopting an integral profile method and applying it to a cylindrical geometry in order to predict the rate at which metal will solidify against a finite rotating cylindrical wall and the rate at which it subsequently remelts,and, 2. deriving the equations governing the relevant rate cont-rolling dissolution mechanisms.This theoretical work has involved the development of a model for unsteady conductive/convective heat transfer in a liquid metal, and an investigation into the mass transfer processes controlling the dissolution of lead and tin into lead/tin alloys. The results obtained in this work can be used to predict the heat and mass transfer conditions under which successful solidification cladding process can be carried out on an industrial scale.