Potassium ionic exchange in glasses for mechanical property improvement

•Potassium ionic exchange•Interdiffusion coefficient•Infrared spectroscopy•Structural glass•Depolymerization of network silicate glass

The aim of this work is to obtain information on structural modification of glass during potassium ionic exchange for mechanical reinforcement. These modifications are evaluated by two characterization methods; scanning electronic microscopy and Fourier transform infrared spectroscopy. The SEM study gives the potassium concentration profile, allows the kinetics of ionic exchange to be observed and gives access to the interdiffusion coefficient with a good concordance between theoretical and experimental concentration profiles. We have verified that the exchange is done between Na+ and K+ ions. We have coupled this SEM result to infrared spectroscopy measurements in middle and far infrared ranges and have proved that infrared spectroscopy allows the access of the structural evolution of glass near the surface after chemical tempering. The evolution of the stretching vibration of Qn modes, between 850 and 1250 cm− 1, shows a depolymerization of the silica network. The Gaussian positions of Qn modes evolve with the exchange time and prove that there is an increase in the rigidity of the silica network due to a compression state.