The surface layer formed after leaching and subsequent heat treatment of an alkali lead silicate glass was studied. The glass was leached in 1 N HCl solution and subsequently heat treated in vacuum at 525°C. The surface was characterised with secondary ion mass spectrometry (SIMS) and the leachate solution was analysed by spectrochemical methods. The leaching kinetics of Pb were found to follow a t1/2 dependence for short times, indicating an interdiffusion mechanism between Pb2+ and H3O+ ions. For longer times the leaching rate of Pb showed a linear dependence with time. This was attributed to the formation of a hydrated gel like SiO2 rich layer at the surface of the glass in which ions have a very high mobility similar to that of ions in solution. Heat treatments of the leached glass in vacuum resulted in preferential segregation of alkali into the leached surface layer. However, the heat treated surface was resistant to further leaching of lead indicating densification of the SiO2 gel layer.
|Original language||English (US)|
|Number of pages||5|
|Journal||Physics and Chemistry of Glasses|
|State||Published - Dec 1 1996|
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Physical and Theoretical Chemistry