Alumina/molybdenum nanocomposites obtained by colloidal synthesis and spark plasma sintering

• Published in: Ceramics international 2023-03, Vol.49 (6), p.9432-9441
• Main Authors: Fernández-González, D., Suárez, M., Piñuela-Noval, J., Díaz, L.A., Gómez-Rodríguez, C., García Quiñonez, L.V., Borrell, A., Fernández, A.
• Format: Article
• Language: English
• Subjects: Alumina; Ceramics; Cermets; Composite materials; Mechanical properties; Sintering; Spark plasma sintering
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2022.11.108

Alumina/molybdenum nanocomposites were prepared by colloidal synthesis from alumina powder and molybdenum (V) chloride using ethanol as dispersion medium. Modified alumina was calcined at 450 °C in air atmosphere to remove chlorides, and then treated in a tubular furnace at 850 °C under Ar/H2 to reduce the MoO3 formed in the previous stage and obtain Al2O3 with molybdenum nanoparticles on the surface. Three different molybdenum contents were proposed (1, 5 and 10 wt % Mo), and pure alumina was used as reference, that were sintered by spark plasma sintering (SPS) under vacuum atmosphere at 1400 °C for 3 min with an applied pressure of 80 MPa. Composites were characterized by microstructure, hardness, toughness, and three-point bending test. The presence of molybdenum nanoparticles resulted in a fine-grained structure promoted by the presence of molybdenum at grain boundaries and triple points, as well as by the utilization of the SPS equipment. Hardness is at least a 20% greater and fracture toughness 30% larger in the composites than in the monolithic alumina.