Mechanical and Magnetic Properties of Novel Yttria‐Stabilized Tetragonal Zirconia/Ni Nanocomposite Prepared by the Modified Internal Reduction Method

Abstract

Dense ceramic/metal nanocomposite has been fabricated by internal reduction method, which includes a two‐step process: sintering of ceramic–metal oxide solid solution and subsequent heat treatment in a reducing atmosphere to precipitate metal nanoparticles. This novel technique has been applied to yttria‐stabilized tetragonal zirconia (Y‐TZP) and nickel oxide (NiO) system to fabricate Y‐TZP/Ni nanocomposite. Dense Y‐TZP and 0.3 mol% NiO solid solution ceramic was successively prepared by the pressureless sintering, and Y‐TZP/Ni was fabricated by the internal reduction treatment. The obtained Y‐TZP/Ni nanocomposite possessed characteristic intragranular nanostructure with nano‐sized metallic Ni particles of around 20 nm. Fracture toughness of both the solid solution and nanocomposite was remarkably improved because of the solid solution of NiO into Y‐TZP and resultant destabilization of the tetragonal phase, and the Y‐TZP/Ni nanocomposite was still destabilized by the remaining nickel solution after the reduction. The nanocomposite exhibited ferromagnetism, while the Y‐TZP–NiO solid solution had diamagnetic nature. Comparison of saturation magnetization values revealed that 39.5 at.% of introduced nickel was reduced to metallic nanoparticle, proving the existence of residual NiO solute in zirconia that contributed to higher toughness value than the monolithic Y‐TZP. It is concluded that the introduced internal reduction method is a suitable process to achieve multifunctional ZrO2/Ni nanocomposite with high toughness and coexistent magnetic characteristic.

Percolative BaTiO3–Ni composite nanopowders from alkoxide-mediated synthesis

“…1 Nanocomposite materials have been extensively explored for many technological applications due to specific combinations of mechanical, optical, catalytic, electrical or magnetic properties with fundamentally different properties that cannot be achieved for single phase, pure materials. [2][3][4] Ceramic-metal nanocomposites are promising candidate materials for fabricating multifunctional nanodevices due to sometimes outstanding electrical properties with very particular features. 5,6 In order to realize an optimized microstructure for ceramic-metal nanocomposites, much effort has been undertaken concerning the control of the size and distribution of the metal nanoparticles.…”

Synthesis of Monoclinic and Cubic ZrO2 Nanoparticles from Zircon

“…Dispersion of nanoscale particles into the ceramic matrix is used to improve the mechanical properties of a ceramic‐based nanocomposite system. The incorporation of nanoparticles in the ceramics matrix facilitates considerable modification of the behavior of the ceramics, which exposes new functions such as superplasticity or high machinability like metal 17 …”

Electrical discharge machining of metal doped Y-TZP/TiC nanocomposites

“…It was shown that inclusions of nanoscale secondary metallic phases into ceramic matrices have beneficial effects on both hardness and toughness of zirconia [14,15] and alumina [16]. An extensive review on ceramic/metal micro-and nanocomposites is presented by Moya [17].…”