The sintering behavior of Al 2 O 3-NbC nanocomposites fabricated via conventional and spark plasma sintering (SPS) was investigated. The nanometric powders of NbC were prepared by reactive high-energy milling, deagglomerated, leached with acid, added to the Al 2 O 3 matrix in the proportion of 5 vol.% and dried under airflow. Then, the nanocomposite powders were densified at different temperatures, 1450-1600 °C. Effect of sintering temperature on the microstructure and mechanical properties such as hardness, toughness and bending strength were analyzed. The Al 2 O 3-NbC nanocomposites obtained by SPS show full density and maximum hardness value >25 GPa and bending strength of 532 MPa at 1500 ºC. Microstructure observations indicate that NbC nanoparticles are dispersed homogeneously within Al 2 O 3 matrix and limit their grain growth. Scanning electron microscopy examination of the fracture surfaces of dense samples obtained at 1600 ºC by SPS revealed partial melting of the particle surfaces due to the discharge effect.

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This study aims to investigate the dry sliding wear behavior of Al 2 O 3 -5vol.% NbC nanocomposites sintered by two different consolidation techniques: conventional sintering (CS) and spark plasma sintering (SPS) at temperatures ranging from 1450 to 1600°C. The dry sliding wear tests were performed on a tribometer with a ball-on-disc configuration using an Al 2 O 3 ball as a counterpart material, with a normal contact load of 15 and 30 N, a sliding distance of 2000 m and a sliding speed of 0.1 m/s at room temperature and ambient environment. The sintering methods, mechanical properties and applied load acted directly on the wear mechanism of the nanocomposites. The samples sintered by SPS exhibited higher densification and hardness, in addition to a lower friction coefficient and wear rate. Based on the wear rate, these nanocomposites exhibited a moderate regime with 15 N of load, and several regimes when 30 N of applied load was used. The main wear mechanisms observed were plastic deformation, abrasion and grain pull-out. The excellent results show that Al 2 O 3 -NbC nanocomposites are ideal for the manufacture of new products such as cutting tools. K E Y W O R D Salumina-niobium carbide, ceramic-matrix composite, cutting tools, sliding wear, spark plasma sintering