Effect of potassium hydroxide content in the molten salt on the chemical strengthening of aluminosilicate flexible glasses

Flexible glass has a wide range of applications in the fields of flexible display, OLED lighting and photovoltaic conversion. Chemical strengthening is one of the most effective methods of enhancing the performance of flexible glass. Through appropriate adjustment of the composition of molten salt in chemical strengthening, the scratch resistance and bending strength of chemically strengthened flexible glass could be enhanced ulteriorly. In this paper, the effects of KOH content in molten salt on glass mechanical properties, alkali metal ions distribution and structure of high aluminum flexible glass are investigated by mechanical performance testing equipment, electron probe microanalyzer and Raman spectroscopy, and the diffusion coefficients were calculated by the Boltzmann-Mattano method. The results demonstrate that the increased interstitial space in the glass caused by the KOH added in the molten salt modifies the surface state of the glass and depolymerises the glass network structure, resulting in an increase in the diffusion coefficient of K⁺. The combined effect of these results is the enhancement of the mechanical properties of the chemically strengthened flexible glass. In comparison with glass samples devoid of KOH in the molten salt, the surface compressive stress of the glass increased from 870.71 MPa to 918.52 MPa, and the depth of the stress layer increased from 14.06 μm. to 15.58 μm, the breakage bending radius decreased from 7.79 mm to 7.13 mm at a content of 0.3 wt% of KOH in the molten salt. And the Vickers hardness did not reduced when KOH content in the molten salt is below 0.3 wt%.