The availability of thin, flexible, and damage-resistant glasses is a key requisite for many of today's glass applications, including windshields, façade elements, or display covers for personal electronic devices. Brittleness and the high susceptibility of glasses to surface flaws result in catastrophic failure under load, with attainable practical strengths far below the theoretical limits. 1 This problem has stimulated intensive research on the fundamental deformation modes in glasses and their implications for the generation of surface defects. 2,3 At the same time, various methods are employed which enhance the practical strength of glasses. 4 Among these, the most popular are to equip the glass product with a residual surface compressive stress layer through thermal or chemical post-processing. 5 Chemically strengthened glasses are produced through diffusive ion exchange, which typically involves the immersion of an alkali-containing glass into a

Glass samples of two different chemical compositions were strengthened by ion exchange. Residual stress profiles were experimentally determined by differential surface refractometry. The experimental results were compared with values theoretically predicted by a formalized viscoelastic mathematical model incorporating both stress buildup and stress relaxation contributions. The comparison exhibited a remarkable agreement both in terms of strengthening characteristics and stress profiles curves between experimentally measured and theoretically predicted values. The mathematical model incorporated terms directly linked to selected relaxation mechanisms either isochoric shear stress driven and fast relaxation. The comparison demonstrated the relevance of the stress relaxation mechanisms for the different glass chemical compositions. The approach presented in this study will allow the prediction of the mechanical behavior of chemically strengthened glass starting from its chemical composition together with the ion exchange process parameters.

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This work focuses on the effect of surface cleaning treatments of soda‐lime‐silicate float glasses before chemical strengthening where a compressive stress layer is introduced via ion exchange. As‐received and cleaned glass surfaces were subjected to two different treatments using demineralized water and acidic solutions were subjected to ion exchange in a molten KNO3 bath for 8 hours at 450°C. Precleaning treatment leads to a relative enhancement of the potassium surface concentration following chemical strengthening as compared to the uncleaned samples, also reflecting in altered surface stress profiles and case depth. These observations provide guidance for optimal pretreatment conditions of glass for chemical strengthening. Appropriate cleaning treatments can result in higher achievable fracture loads of subsequently chemically tempered glasses in ring‐on‐ring biaxial bending tests.