Effect of K ₂ O/Na ₂ O addition on the microstructure and mechanical properties of CaO‐MgO‐Al ₂ O ₃ ‐SiO ₂ glass ceramic

Abstract This work studied the effects of types of flux (K 2 O and Na 2 O) and sintering temperature on the microstructure and mechanical properties of augite‐based glass ceramics (GCs). Fine glass powder ( D 50 = 1.07 µm) was used as the starting material for preparing the GCs. The porosity of the samples decreased by increasing the sintering temperature from 850°C to 925°C, and a further increase in the sintering temperature to 950°C caused an increase in porosity from 0.2 to 1.8 vol%. The substitution of K 2 O for Na 2 O reduced the densification degree of GC. Nevertheless, K 2 O refined the grain size of augite to 24–33 nm, which enhanced the hardness of GC. Both Na 2 O‐containing and K 2 O‐containing GC prepared at 925°C showed their highest bending strength (GC‐Na: 225 MPa, GC‐K: 215 MPa) and Vickers hardness (GC‐Na: 8.39 GPa, GC‐K: 8.41 GPa).