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

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 (WR) 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, WR 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. Keywords: Wear, Solid lubricant, Micro-nanostructure, Glass-ceramic, Hardness, Fracture toughness