The ion exchange process typically entails substituting ions within the glass network with ions derived from a molten salt bath. The glass is immersed in a molten salt bath containing ions that can diffuse into the glass structure. Commonly, sodium ions in the glass are displaced by larger ions such as potassium from the molten salt. Figure 1 depicts a schematic representation of the ion-exchange process. This transformative process modifies the physical and chemical properties of the glass, resulting in enhanced mechanical strength, heightened chemical durability, and alterations in optical properties. Ion exchange finds widespread application in the manufacture of strengthened glass utilized in diverse sectors, including electronic devices, touchscreens, and optical lenses. The controlled nature of this process enables the customization of glass properties to meet specific requirements for various industrial applications.

The objective of this study is to investigate the potential application of a nonuniform electric field to enhance the generation of targeted ion diffusion patterns during the ion exchange process. The work is organized into two main sections: the experimental section and the modeling section.

1. Experimental section

Diverse samples under varied conditions were meticulously prepared using a custom-designed experimental setup tailored for electric field ion exchange. Figure 2 illustrates this setup. The prepared samples underwent comprehensive analysis employing a diverse range of techniques, including EDS-Line, variable angle spectroscopic ellipsometry (VASE), Vickers hardness measurements, indentation toughness calculations, and bending strength testing.

This study has yielded noteworthy findings that hold potential for publication in academic journals. As an illustrative example, Figure 3 visually represents a glass article subjected to ion exchange solely on one side, resulting in a noticeable bending effect—likely attributed to the presence of compressive stress.

2. Modeling section

In this section of the study, we aimed to address a series of inquiries concerning the depth of layer (DOL) and compressive stress (CS). The research questions are outlined as follows:

1- How does the depth of layer (DOL) change in relation to the chemical composition of the glass batch and various process parameters?

2- How does compressive stress (CS) fluctuate based on the chemical composition of the glass batch and different process parameters?

3- Which parameters exhibit the most significant influence on the depth of layer (DOL) and compressive stress (CS)?

4- Lastly, and notably, what constitutes the optimal glass batch composition and process parameters in terms of achieving the desired depth of layer (DOL) and compressive stress (CS)?

Publications:

[1] Banapour Ghaffari, O., B. Eftekhari Yekta, and M. Zakeri-Nasrabadi, Estimating “depth of layer” (DOL) in ion-exchanged glasses using explainable machine learning. Materialia, 2024. 33: p. 102027.DOI: https://doi.org/10.1016/J.MTLA.2024.102027
[2] Banapour Ghaffari, O., B. Eftekhari Yekta, and M. Zakeri-Nasrabadi, Designing High-Performance Ion-Exchangeable Glasses with Multi-Objective Optimization and Machine Learning. Ceramics International, 2024.DOI: https://doi.org/10.1016/j.ceramint.2024.08.141.