Fabrication of Al2O3-ZrO2-Ni composites with improved toughness using nano powders prepared by mechanical alloying

Abstract

It has been established that the production of structural ceramic/metal composites with improved toughness has a great of interest for industrial applications. Al2O3-10 wt % ZrO2 sintered composites reinforced with 0, 3, 6, 9 and 12 wt % of Ni were fabricated from nano powders prepared by mechanical milling method. The phase identification, crystal size, morphology and particle size of obtained powder were examined by XRD and TEM, respectively. The powder was compacted and sintered at various temperatures up to 1550 °C. Relative density and apparent porosity of fired composites were determined by water displacement method whileas their microstructure was investigated by SEM. Mechanical and electric properties of sintered specimens were also determined in details. The results revealed that nano powders were successfully prepared after milling for 20h. The particle and crystal sizes increased while lattice strain and dislocation density decreased with increasing Ni content. For the sintered composites, the microhardness, compressive strength and elastic moduli reduced when the Ni content increased while they improved with rising sintering temperature. The fracture toughness improved with increasing both Ni content and sintering temperature. For AZ12Ni composite sintered at 1550 °C, it exhibited the maximum fracture toughness (6.5 MPa m0.5). The electrical-resistivity reduced with rising both Ni quantity and firing temperature. While the dielectric constant and dielectric loss reduced with higher Ni content but they increased with rising firing temperature. The electrical resistivity, dielectric constant and dielectric loss of AZ12Ni composite sintered at 1550 °C were 8.94 × 109 Ω m, 7.47 and 2.8 × 10−5, respectively.