Prof. Dr. VINCENZO M. SGLAVO
Department of Industrial Enginnering
University of Trento, IT
Vincenzo M. Sglavo is professor of materials science and technology at the Department of Industrial Engineering, University of Trento (Italy). He received the Laurea degree “cum laude” in Materials Engineering from the University of Trento in 1988.
In 1989, he joined the Department of Materials Engineering, University of Trento, as Assistant Professor, and in 1999 became Associate Professor. Since May 1993 to August 1994 he worked as Post Doc Fellow at the Department of Materials Science and Engineering, The Pennsylvania State University, USA where he went back as Adjunct Professor in 2001. He has been appointed as Full professor of Materials science and technology at the University of Trento in June 2019.
His current research interests include fracture phenomena in glasses and ceramics, strengthening of glass by ion-exchange, electrical field-assisted sintering and materials for solid oxides fuel cells. Author of more than 180 scientific papers and 12 patents, Prof. Sglavo is member of the American Ceramic Society, the Society of Glass Technology and the Italian association of professional engineers.
Chemical Strengthening Of Silicate Glass: Processing Issues And Innovations
Ion-exchange process has gained remarkable interest during the last years for chemical strengthening silicate glasses because of its suitability and flexibility in the reinforcement of components with different geometry and thickness. During a typical industrial process, sodium atoms contained in the glass are substituted by potassium ions diffusing from molten potassium nitrate at temperatures below the strain point of the glass, thus creating a bi-axial residual compressive stress in the material surface which strengthens the component.
After a brief analysis of the ion exchange process fundamentals, two main aspects regarding processing issues and innovative procedures are discussed.
At first, an interesting aspect regarding the presence of impurities in the bath, introduced with the raw salt or accumulated during the process and responsible for the resulting performance is pointed out. Analyses of commercial soda lime silicate float glass and sodium borosilicate glass are reported and the effect of variable sodium, magnesium and calcium concentration in the molten bath on the efficiency of the ion exchange process is analyzed. The performances of chemically strengthened samples in terms of potassium penetration profile, residual stress and mechanical strength are studied. The addition of limited quantities of silica is also advanced as possible remedial action for non-efficient salts.
Then, an innovative process where an electric field – assisted ion exchange is carried out to enhance sodium-potassium interdiffusion and improve the mechanical performances of soda-lime-silicate and soda-borosilicate glass is presented. Electric fields with variable intensity are applied cyclically in both direct and inverted polarization. Mechanical tests are used to characterize the performances of the strengthened material. Spectroscopic analyses are also carried out to determine the potassium concentration in the surface layers of the samples. It is shown that the application of the electrical field allows to enhance Na-K interdiffusion to a large extent, thus reducing the treatment time well below the hour. The cyclic process allows to reinforce both surfaces thus allowing to reach very high mechanical strength.