The Role of Tin in Copper Ruby Glass
-Viscosity Measurements |
ATMA RAM*, s. N. PRASAD, K. P. SRIVASTAVA AND B. N. GHOSH
Pages : 79-85
DOI : 10.1080/0371750X.1973.10840566 |
Abstract |
A new mechanism for striking of colour in copper ruby glass was recently suggested: 2 Cu -0-Si =
(chilled glass) striking-+Cu20 (red colourant)+=Si-0-Si=. It does not need tin, considered
essential as per the earlier mechanism. The actual role of tin has therefore been investigated. A copper
ruby glass melted without tin became amber indicating the presence ofCu0
• For confirmation, its low
temperature viscosiry has been studied. Viscosiry of chilled glass remains unchanged on annealing.
This indicates presence of Guo in chilled glass rather than of Cu+ which, on annealing, would have
increased the viscosiry several fold due to formation of bigger structural linkages. Hence in absence·
of tin the reduction of Cu+ to Cu0 is almost instantaneous in the melt and the latter makes the glass
amber. Cu+ being absent, formation of Cu20 (red colour ant) is not possible on striking. But when
tin is used, availabiliry ofCu+ is prolonged. It is likely that tin acts as a protector for Cu+ in molten
glass. Probably reaction Sn2+-+ Sn° takes place in preference to Cu+-+ Cu0
• Thus when tin is used,
Cu+ is available in the freshly shaped glass-ware and on striking, Cu20, the red colorant, is produced. |
Full text : Subscribe to Download Full Text |
[Go Back] |
|