Effect of sintering atmosphere on composition and properties of NiFe₂O₄ ceramic

Abstract

NiFe₂O₄ ceramics were prepared in different sintering atmospheres. The phase compositions, microstructures and mechanical properties were studied. The results show that the stoichiometric compound NiFe₂O₄ cannot be obtained in vacuum or atmospheres with oxygen contents of 2×10⁻⁵, 2×10⁻⁴ and 2×10⁻³, respectively. All the samples sintered in above-mentioned atmospheres contain phases of NiFe₂O₄ and NiO. With increasing oxygen content, NiFe₂O₄ content in the ceramic increases, while NiO content appears a contrary trend. In vacuum, NiFe₂O₄ ceramic has average grain size of 3.94 μm, and bending strength of 85.12 MPa. The changes of the phase composition and mechanical properties of NiFe₂O₄ based cermets are mainly caused by the alteration of their properties of NiFe₂O₄ ceramic.

Keywords

NiFe₂O₄ ceramic / microstructure / mechanical property / sintering atmosphere

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