Engineered stress-profile silicate glass: High strength material insensitive to surface defects and fatigue

A modified ion-exchange process can be used for the production of high strength glass, which is, in addition, insensitive to surface flaws. In such ESP-Glasses (Engineered Stress Profile) the residual stress profile possesses a maximum compression at a certain depth from the surface, which, conversely, is almost stress free. Such unusual stress profile allows a stable and controlled growth of surface defects before final catastrophic failure. In this way the strength can be independent from the size of pre-existing surface flaws in a certain range of crack size and possess limited scatter. In the present work, three commercial silicate glasses have been used for the production of ESP glass.