Fabrication and characterization of hot pressed Al2O3–SiC fibrous monolithic ceramics

Fibrous Monolithic Ceramics (FMs) in many of cases are inexpensive alternatives for replacing the ceramic composites that reinforced with continuous fibers. Additionally, the FMs composites provide higher fracture toughness. For fabrication of monolithic specimens, alumina-based composites with 5, 10, 15, 20 and 25 wt% of silicon carbide and 0.5 wt% of titanium hot pressed at 1550 °C under the pressure of 30 MPa for 1 h. Then, the fibrous monolithic ceramics, containing core and shell with the diameter of 1 mm manufactured. The core of (FMs) containing 90 wt% alumina, 10 wt% silicon carbide and 0.5 wt% titanium dioxide, surrounded by graphitic shells. core to shell volume fraction ratios (65: 35 and 75: 25) produced by extrusion method. For the second step, the fibers were laid out in the cold press in two different directions of 0°, 0 /90°. then they were pressed with a load of 30 MPa. After that, the specimens hot pressed under the pressure of 30 MPa at 1550 °C for 1 hour. For the monolithic composites containing 5 wt % silicon carbide, maximum fracture toughness and hardness measured and values about 5.9 (MPa.m1/2) and 2085 HV. The highest flexural strength of 634.75 MPa was obtained for the specimen with 25 wt% silicon carbide. For the FMs specimens, due to the reduction of the cell boundary thickness, the crack deflection and crack delamination in the cell boundary increased, and the maximum value of fracture toughness increased up to 8.9 MPa .m1/2.