oa Reduction of Platinum Corrosion in Molten Glass

In order to ensure the high quality necessary for use in scientific instruments, most high-technology optical glasses are melted in platinum containers. In general, this noble metal has excellent corrosion and erosion resistance, as well as low solubility, when in contact with molten glass. Therefore the dangers of discoloration and reduction in optical transmission are low. Glass melts may be contaminated by the uptake of corrosion and erosion products if the glass is melted in ceramic materials. The use of platinum, instead of ceramics, for both containers and stirrers enables glass melts to be stirred more thoroughly and hence become more homogeneous. In this way a better quality and higher yields of glass are obtained. Even totally new glass systems which have superior optical properties, but which would attack ceramics very quickly, can be melted in platinum vessels and produced to extremely high quality. Generally, platinum or its alloys enables optical glass to be produced with high purity, homogeneity and the absence of streaks and bubbles.