Fabrication and mechanical properties of short ZrO2 fiber reinforced NiFe2O4 matrix composites

Short ZrO2 fibers (ZrO2(f)) reinforced NiFe2O4 ceramic composites were fabricated by cold pressing process. The phase composition, microstructure, mechanical properties and fiber/matrix interface of the composites were investigated by X-ray diffraction, scanning electron microscopy and mechanical testing machines. ZrO2(f) show good thermodynamic and chemical compatibility with NiFe2O4 ceramic matrix and effectively enhanced the mechanical properties. The toughening mechanisms are fiber bridging, interfacial debonding, fiber pullout, phase transformation and the matrix constraint effect. By incorporation of 3 wt% fibers with the average length of 5∼6 mm, the bending strength and fracture toughness of the composites reached 88.92 MPa and 4.62 MPa m1/2, respectively, while the strength conservation ratio after thermal shock increased from 48.85% to 75.86%. The weak interface bonding built up between ZrO2(f) and NiFe2O4 facilitates the reinforcing effects of the fibers to operate.