Oxidation mechanism and kinetics of TiB ₂ submicron powders in air

Abstract High‐activity TiB 2 submicron powders were synthesized via microwave‐assisted carbothermal reduction, and their oxidation behavior at 550°C–1000°C for 0.5–1.5 h in air atmosphere was carried out by the isothermal oxidation test. The phase composition and microstructure evolution of the oxidation products were performed by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). It was established that TiB 2 submicron powders had been significantly oxidized at 550°C, and the oxidation products were TiO 2 and B 2 O 3 . Hexagonal plate‐like TiB 2 grains had been completely disappeared, and fragmented into uniform nano‐scale spherical TiO 2 particles after being oxidized at 1000°C for 1 h, accompanied by the violent evaporation of B 2 O 3 products at temperatures above 1000°C. In addition, the corresponding oxidation kinetics was investigated by using a non‐isothermal thermogravimetric (TG)–differential scanning calorimetry (DSC) technique. The results showed that the Mample power law ( n = 1) was the most probable mechanism function, and the oxidation activation energy E of TiB 2 submicron powders was 640.58 kJ/mol.