**3.5 Determination of the fracture toughness KIC**

For the SCB test, after the crack starts from the disc center at the maximum load, the crack propagates symmetrically ahead the loading diameter. KIC is determined by applying Eq. (1), the KIC is calculated for different percentages of TCP.

**Figure 12** shows the fracture toughness of different amounts of TCP added to Alumina. As sintered at 1600°C/1 h, The best value of the fracture toughness value of Al2O3/10 wt.% TCP composites is 8.76 MPa m1/2.
