Which of the following statements describes why ion exchange of 99% SiO2 - 1% B2O3 in a salt bath of molten postassium chloride (KCl) is not an effective way to increase the surface strength of the glass sample?
The ion exchange works correctly, however both air-cooling and water-quenching are more efficient ways to induce a surface strengthening effect.
The glass is composed of only 1% B2O3, which is not a large enough proportion of B2O3 to undergo ion exchange, and therefore does not increase the surface strength of the sample effectively.
The potassium ion is smaller than B2O3, so when ion exchange takes place the surface is actually being weakened instead of strengthened.
The sample described above is composed of SiO2 and B2O3. Neither of these components are network modifiers, so ion exchange does not take place to strengthen the surface of the glass.
The surfaces of the glass sample are not cooled quickly enough to create a high internal strain energy that leads to strong surfaces.
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