Nickel-boron nanolayer evolution on boron carbide particle surfaces during thermal treatment

This study is focused on reduction of Ni₂O₃ and B₂O₃ in the Ni-B nanolayer on B₄C particle surfaces and understanding of the nanolayer composition and morphology changes. Initially, the nanolayer contains Ni₂O₃, B₂O₃, and amorphous boron. After 400 °C thermal treatment in a H₂-Ar atmosphere, Ni₂O₃ is reduced to nickel; the nanolayer morphology is maintained and the coated particles demonstrate magnetism. As the thermal treatment temperature is increased to 550 °C, B₂O₃ is reduced to boron, which reacts with nickel and forms Ni₂B. Simultaneously, the nanolayer evolves into nanoparticles. Thermal treatment temperature increase to 700-900 °C only causes Ni₂B particle growth but does not fundamentally change the composition or phase.