Large-Area Atomically Thin WS₂ Enables Exceptionally Scratch-Resistant Silica Glass

Beyond aesthetics, scratch damage on glass surfaces significantly affects their mechanical strength and other critical functionalities. Here, it is demonstrated that the large-scale growth of atomically thin WS₂ films on silica glass via chemical vapor deposition can result in ultra-scratch-resistant surfaces. Through rigorous scratch tests using atomic force microscopy, it is observed that even a monolayer of WS₂ can subdue nanoscale friction by ≈95%, effectively averting severe plowing wear. Instead, minor distortions of the glass surface are recorded owing to the combined load-bearing and low-shear WS₂ monolayer. To elucidate the mechanism behind the exceptional scratch resistance, atomistic simulations are employed, which reveal that while WS₂ evidently shields the normal stresses during indentation, nominal shear stresses eventually act on the glass during scratching. Consequently, shear-induced bond-breaking and bond-switching transitions are observed in the contact subsurface that prematurely densify the silica network as a non-wear dissipating mechanism. Altogether, the present study showcases the potential of two-dimensional WS₂ coatings for new-generation scratch-resistant glass and provides fresh perspectives into their protection mechanisms.