Development of high strength and tough nickel slag-aerogel ceramics

Nickel slag-SiO2 aerogel porous ceramics with low density and high porosity (HPLD) were prepared successfully. However, the application is also limited by poor flexural strength and fracture toughness. To optimize this, we explored a composite foaming method using nickel slag as a raw material that was associated with various toughening agents. The effects and mechanism of the sintering temperature, holding time and toughening agent on the performance were revealed. The results showed that the optimum sintering temperature was 1020 °C, and the holding time was 120 min. Various toughening methods can enhance fracture toughness and strength in ceramics, although the self-toughening method of zirconia demonstrates the most favourable effects. This method involves the production of nail-like structures that become firmly embedded in the cordierite and anorthite crystal phase at high temperatures. This structure resists a portion of the energy released during external concentrated stress, thus promoting a marked increase in both strength and toughness. Compared to the control group, the incorporation of zirconia resulted in a compressive strength of 0.7 MPa and a fracture toughness of 5.11 MPa m1/2, representing impressive 75.0 % and 82.5 % increases, respectively. Additionally, the flexural strength increased by nearly 200 % compared to that of the control group.