Additive effect in salt bath for glass strengthening

We introduce the additives effect in the molten salts such as commercially pure KNO3 and polluted KNO3. The results showed that in case of the commercial purity KNO3, only KOH improved the compressive stress (CS) of ion-exchanged glasses up to ∼50 MPa, and the others additives did not make the CS improvement. Rather than the CS was diminished by additive contamination. In case of the contaminated KNO3, the additives K3PO4, K2CO3, and K2SO4 successfully removed the impurities, Na+, Ca2+, Mg2+, by precipitating chemical compounds in molten bath and recovered the CS up to ∼97 %. X-ray diffraction (XRD) results proved how the harmful ions in molten salt was removed by adding additives.