Al2O3-Fe2O3 composites obtained by colloidal processing route and sintered by spark plasma sintering: Microstructure and properties

Al 2 O 3 -Fe 2 O 3 ceramic composites were prepared for the first time by colloidal synthesis from alumina powder and Fe(NO 3 ) 3 ·9(H 2 O) using water as the dispersion medium. Doped alumina was treated at 600 °C under air atmosphere to thermally decompose the ferric nitrate and obtain Al 2 O 3 with Fe 2 O 3 nanoparticles on the surface. Five Fe 2 O 3 contents were studied (1, 2.5, 5.0, 10.0, and 20.0 wt%). Monolithic alumina was used as a reference to analyze the influence of the Fe 2 O 3 content on the properties of the composite. Sintering was carried out in a spark plasma sintering (SPS) apparatus under a vacuum atmosphere at 1400 °C for 3 min, with an applied pressure of 80 MPa. The mechanical and electromagnetic properties of the composites were correlated with the microstructure of the composites. This way, the presence of the Fe 2 O 3 nanoparticles promoted a fine-grained structure, which leads to an increase in the fracture toughness in the case of the composites with <5 wt% Fe 2 O 3 . The addition of Fe 2 O 3 is deleterious to the mechanical resistance in the three-point bending test. Regarding electromagnetic properties, all the samples present a soft magnetic behavior with coercive fields. The samples with the largest Fe 2 O 3 content (10 and 20 wt%) show a noticeable transverse Kerr effect, ranging up to 0.15% in the UV region.