Glass melting unit

摘要

A material which is suitable for the components of a glass melting unit which is employed in both continuous and batch processes comprises metallic zirconium. Due to the high corrosion resistance of zirconium, it is not necessary to use expensive noble metals during melting of aggressive substances. In the case of high-quality, optical glasses, an improvement in quality is achieved by a reduction in the formation of streaks (schlieren) and the prevention of the crystallisation of dissolved noble metals. In order to prevent atmospheric oxygen attacking the zirconium, the parts which are not wetted by the glass melt are either flushed by an inert gas or protected by a refractory covering containing a reducing agent. A further possibility is to carry out the melting under reduced pressure.