Investigation of tin penetration at bottom surface of float borosilicate glasses

Tin penetration at the bottom surface of float borosilicate glasses was studied. The changes of tin penetration depth with different reaction temperatures and times were studied by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. The results showed that tin penetration layer could not be observed until 850°C. The tin penetration depth increased with increasing reaction temperature from 850 to 950°C, while it decreased with further increasing temperature from 950 to 1050°C. X-ray photoelectron spectroscopy (XPS) was employed to study the mechanism of the decrease occurred from 950 to 1050°C. The coexistence of Sn0 and Sn2+ ions and the changes of relative concentration ratio between them in the tin penetration layer were investigated by XPS.