Effect of Nickel Doping Amount on Structure and Properties of Ni/FeCr₂O₄ Composites Prepared by Sintering

With nickel powder, Fe₂O₃, Cr₂O₃ and polyvinyl alcohol as raw materials, Ni/FeCr₂O₄ spinel structure composites with different nickel doping amounts (20%, 25%, 40%, mass fraction) were prepared by powder sintering method. The effects of nickel doping amount on the microstructure and properties of Ni/FeCr₂O₄ composites were studied by X-ray diffractometer, infrared spectrometer, scanning electron microscope, and mechanical tester, etc. The results show that with increasing nickel doping amount, the composite structure became denser and the volumetric shrinkage and density increased; the flexural strength was significantly improved. When the nickel doping amount was 40%, the density and flexural strength was improved by 17.3% and 22.5%, respectively, comparing with those of non-nickel doping. Nickel doping improved the emissivity of FeCr₂O₄ spinel around the wavelength of 1 000 nm, and slightly reduced the emissivity in the wavelength range of 250-700 nm and 1 200-1 600 nm, but the emissivity in these two bands was still higher than 0.9.