The freeze-coating of filaments

Abstract

The coating of filaments of glass or of other materials by passing them through a molten metal globule is described. An analysis of the process of freezing by the radial conduction of heat into the fibre is given and good agreement found between predicted and measured values of the coating thickness. `Blobs', large lumps of metal adhering to the fibre, are shown to be caused by the presence of the oxide film surrounding the metal globule and can be eliminated by using an inert gas blanket. There is a discussion of factors affecting the strength of aluminium-coated silica fibres, showing that diameter variation plays only a small part in determining the variance of strength. Chemical interaction at the interface accounts for the largest part.