Effect of Al2O3-NbC nanopowder incorporation on the mechanical properties of 3Y-TZP/Al2O3-NbC nanocomposites obtained by conventional and spark plasma sintering

The incorporation of AlO-NbC-nanopowder reinforcement in a 3Y-TZP matrix, and its influence on the mechanical properties of 3YTZP/AlO-NbC nanocomposites, obtained by conventional and spark plasma sintering (SPS), was investigated. Nanometric powders of AlO-NbC were prepared by reactive high-energy milling, deagglomeration, and leaching with acid, and added to the 3Y-TZP matrix, at a proportion of 5 vol%. The final powders were dried under airflow, compacted, and sintered in the temperature range of 1300–1500 °C. The effects of the sintering technique and final temperature, on the microstructure and mechanical properties, such as hardness, toughness, and Young's modulus, were analysed. Fracture toughness of the material reinforced with AlO-NbC nanopowders, which is one of its most important properties, differed significantly from that of the 3Y-TZP monolith (5.2 MPa m). The nanocomposites, sintered conventionally at 1450 °C, showed higher fracture toughness (8.7 MPa m). Microstructure observations indicated that NbC nanoparticles were dispersed homogeneously within the 3Y-TZP matrix, and limited its grain growth. However, partial oxidation of the NbC on the nanocomposite surface, at the conventional sintering temperature of 1500 °C, caused a reduction in the fracture toughness.The authors acknowledge the Brazilian institutions CAPES-PVE (grant number 23038.009604/2013-12), FAPESP (grant number 2015/07319-8), Fundação Araucária (grant number 810/2014), European Union/Erasmus Mundus for doctorate mobility (grant number EB15DM1542), and the Spanish Ministry of Economy and Competitiveness (grant number IJCI-2014-19839).Peer Reviewe