Enhanced wear resistance of engineered glass-ceramic by nanostructured self-lubrication

Highlights: • Novel micro-nanostructured glass-ceramics obtained by a fast sintering processing route. • Hierarchical micro-nanostructure extremely improves mechanical properties. • Wear mechanism undergone is unlike other glass-ceramics, like a polishing process. • Nanocrystals work as solid lubricants, reducing surface damage suffered. • Very promising candidates to be used in high-performance self-lubricating applications. -- Abstract: A new kind of micro-nanostructured glass-ceramic based on albite and anorthite crystallizations, >90%, has been obtained following a fast sintering processing route. Flexural strength values up to 111 MPa and microhardness values of 9.5 GPa are measured, supposing an improvement of ~60% regarding current glazes for ceramic floor tiles for high transit areas. The hierarchical micro-nanostructuration of these glass-ceramics favour crack deflection, which implies a reduction of brittleness in these materials and a consequent increase of fracture toughness of ~40% regarding a standard glass-ceramic. Tribological properties are also evaluated, showing a decrease in the friction coefficient (μ) of ~36% and a surprising reduction of the wear rate (W_R) larger than one magnitude order, in both micro-nanostructured glass-ceramics, concerning a standard one. Worn tracks analysed by Multi-Mode Optical Profilometry and FE-SEM measurements revealed that nanocrystals present in the microstructure work as solid lubricants, favouring body sliding over their surface and noticeably reducing μ, W_R and the surface damage suffered. Wear mechanism undergone by both glass-ceramics is unlike other glass-ceramics, similar to a polishing process, without any apparent material spalling. All of these findings make the micro-nanostructured materials very promising candidates to be used in high-performance self-lubricating applications.