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.