Surface damage resistance and yielding of chemically strengthened silicate glasses: From normal indentation to scratch loading.

We report on surface elasticity, plastic deformation and crack initiation of chemically strengthened soda‐lime silicate and sodium aluminosilicate glasses during lateral indentation and scratch testing. Instrumented indentation using a normal indenter set‐up corroborated previous findings on the effects of chemical strengthening on surface Young's modulus, hardness, and indentation cracking. Using lateral indentation in the elastic‐plastic regime, we find a pronounced increase in the scratch hardness as a result of chemical strengthening, manifest in higher work of deformation required for creating the scratch groove. Thereby, the glass composition is found to play a stronger role than the absolute magnitude of surface compressive stress. Using a blunt conical stylus for instrumented scratch testing reveals three distinct modes of scratch‐induced surface fracture, which occur during scratching or after unloading. Occasional micro‐cracking caused by pre‐existing surface flaws at low scratching load can be completely suppressed through chemical strengthening. The intrinsic defect resistance to microcracking is reduced as a result of ion stuffing, depending on the initial glass composition, whereas the resistance to abrasive yielding is enhanced by several hundred MPa. [ABSTRACT FROM AUTHOR]