Effect of LaF₃ on Mechanical Performance of Fly Ash Based Cordierite Ceramics

In order to overcome the mechanical weakness of cordierite ceramics based on fly ash, lanthanum fluoride (LaF₃) was introduced in the fabrication process as high efficiency additive, resulting in cordierite ceramics with excellent mechanical properties. When the addition of LaF₃ was 1.0 wt.% and the sintering temperature was 1300 ℃, elastic modulus, hardness and compressive strength of the samples were 200.09 GPa, 17.63 GPa and 118.41 MPa, respectively. The significant enhancement was mainly attributed to the enhanced liquid fluidity and densification effect. At the same time, lanthanum was enriched at grain boundaries to facilitate grain refinement and toughening. Besides, a small quantity of lanthanum might be incoporated into the cordierite lattice, which would have a positive effect on mechanical strengthening.