The effect of single-side ion exchange on the flexural strength of plain float glass and float glass containing a drilled hole

The effect of single-side ion exchange (using a KNO3:KCl mixture) on the ring-on-ring flexural strength of float glass has been studied. Two ion exchanged series, treated at 450 and 515 degrees C, were investigated. The ion exchanged samples showed approximately 160 respectively 100% increases in their arithmetic mean strength compared to as-received float glass. Furthermore, a series of samples containing drilled holes were studied in order to investigate the effect of single-side ion exchange on such common construction elements. The samples that contained drilled holes were ion exchanged at 450 degrees C and showed around 140% increase of the fracture load compared to the untreated samples containing drilled holes. As a general observation, the ion exchange treatment induced similar to 110 MPa compressive stresses (515 degrees C) and similar to 180 MPa compressive stresses (450 degrees C). The ion exchanged samples showed no significant increase in stiffness.