A mathematical model is presented for the concentration of incoming ions in the glass and the residual stress build-up resulting from the ion exchange processes between silicate glasses and a bath of molten alkali nitrate salts. The role of quality characteristics of molten salt is discussed. The discussion covers both thermodynamic equilibrium issues at the glass surface and interface between glass and the molten salts and the interdiffusion non-equilibrium kinetics. Measurement methods and results are reported for surface compression (SC) and compression layer depth (Cd) for different soda-lime glasses: clear, low-iron, and grey body tinted. The discussion of the salt chemistry related to ion exchange chemical strengthening is focused on the service life of plants in the industrial environments. Salts pollution ad their de-activation mechanisms are introduced and critically discussed. Conclusions are summarized and presented, putting in evidence the importance and relevance of this study to the application areas of silicate glasses chemical strengthening by ion exchange.
Guglielmo Macrelli
Chemical strengthening of Silicate Glasses by Ion Exchange: the role of Alkali Nitrate Salts
Company: Isoclima SpA, Italy
About the speaker:
Guglielmo Macrelli is a Glass Scientist. He served as an R&D responsible, then as Chief Scientist, and finally as CTO in Isoclima Spa – Italy from 1992 to 2024. He is presently the Chief Scientific Advisor for Isoclima SpA. He published more than 50 papers mainly peer-reviewed, in the field of Glass Science and technology. He has been invited speaker to several international meetings and congresses.