Hardness and scratch resistance of chemically strengthened alkali-borosilicate thin glass

Chemical strengthening of glass represents a standard technology for fabricating damage-resistant protective covers. Still, little attention has been paid to modifications in the tribological properties of ion-exchanged glass surfaces. This work reports on scratch testing of a chemically strengthened alkali-borosilicate thin glass. Diffusive Na+/K+-ion exchange produces a residual surface compressive layer with compressive stress of 200–340 MPa and layers depths between 16 and 50 µm, depending on exchange temperature and treatment time. This leads to notable changes in the surface mechanical properties, such as an increase in surface Young’s modulus, indentation, and scratch hardness. Surprisingly, the Na+/K+-ion exchange is shifting the onsets of scratch-induced microcracking and microcracking to lower normal loads. The  ccelerated buildup of lateral indentation stress in glasses with high scratch hardness was found to be responsible for the lower threshold loads of microcracking and abrasive wear in chemically strengthened alkali-borosilicate thin glass.