Synthesis, structure and anti-oxidation properties of FeNi nanoparticles coated by BN (hexagonal)

BN-coated FeNi nanoparticles (i.e., FeNi/BN) has been prepared via liquid phase reduction process followed by high temperature calcination. TEM and SEM images confirm the nano-dimensional structure with core/shell structure, with FeNi NPs as core and BN layers as shell. The anti-oxidation performance of the coated and uncoated powders were investigated from room temperature to 900 °C by TGA and DTA, thermal analysis data revealed that the FeNi NPs are oxidized at 220 °C in the air, while the FeNi/BN samples are stable below 570 °C. This results from the fact that the enhancement of the thermal stability by the BN shell. In addition, the BN layers limit the growth of FeNi NPs, resulting in the lower saturation magnetization and higher coercivity, compared with pure FeNi NPs.