Alkali-resistant oxynitride glasses

Oxynitride glasses in the Si–Zr–Na–Li–K–B–O–N system have been produced via incorporation of Si₃N₄into the glass structure. This system is the oxynitride analogue of commercially available alkali resistant (AR) glasses used for concrete reinforcement. Glasses with nitrogen contents up to approximately 4 at.% have been obtained. Hardness, fracture toughness, and chemical durability were found to increase with increasing nitrogen content. Fibers were drawn from the glasses containing approximately 4 at.% nitrogen and used to produce reinforced cement composites. The microstructure of the fiber-matrix interface was examined in these samples after aging and compared to that of oxide AR glass fiber-matrix interface. Measurement of the wetting behavior of aqueous solution as a function of the nitrogen content of the glass suggests that this difference in microstructure is the result of changes in physiochemical properties of the glass surface due to the incorporation of nitrogen into the glass structure.