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Nb₂AlC-Particle-Reinforced ZrO₂-Matrix Composites

M. Stumpf, J. Biggemann, T. Fey, T. Fey, K. Kakimoto, P. Greil

Journal of Ceramic Science and Technology, Vol. 9, No. 3 (2018), pp. 271-278

DOI: 10.4416/JCST2018-00013

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Abstract

Nb2AlC-particle-loaded ZrO2-matrix composites were manufactured by means of pressureless sintering (PS) and spark plasma sintering (SPS) at 1300 °C. The MAX phase Nb2AlC was synthesized based on the reaction of Nb, NbC and Al powder mixtures at 1600 °C in Ar-atmosphere. Nb2AlC formation was confirmed with XRD and ICP-OES. Nano-particulate tetragonal 3Y-TZP powder was mixed with Nb2AlC powder with a mean particle size of 7.93 µm up to a volume fraction of 19.5 %. While the microstructure of the PS composites revealed a residual porosity of 20 – 22 %, almost dense materials with a residual porosity ≤ 2.35 % were obtained by means of SPS. With increasing Nb2AlC fraction a significant improvement of the mechanical properties was observed. An increase in fracture toughness of up to 46 % (PS) and 67 % (SPS) measured on composites loaded with 19.5 vol% Nb2AlC compared to pure 3Y-TZP was attributed to crack bridging of Nb2AlC particles which, depending on the orientation, may attain high strain values owing to basal slip and kink band formation.

Keywords

Nb2AlC, ZrO2, particle composite, toughness

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