Interaction of powdery Al, Zr and Ti with atmospheric nitrogen and subsequent nitride formation under the metal powder combustion in air

The combustion process in air for aluminum nanopowders (nAl), micron-sized powders of aluminum (μAl), titanium (μTi) and zirconium (μZr) was accompanied by the predominant reaction of the metals with N2 and the subsequent stabilization of the nitride phases (from 38 wt.% of ZrN for μZr combustion to 72 wt.% of AlN for nAl combustion) in the condensed combustion products (CCP). The combustion process, composition and structure of CCP of nAl, μAl, μTi, and μZr were studied. Scanning electronic microscopy (SEM), X-ray diffraction (XRD), energy dispersive (X-ray) spectroscopy (EDX), and chemical analysis were performed on both initial powders and CCP. The combustion mechanism for the studied metal powders was experimentally proved. The formation of a large amount of non-equilibrium products (AlN, ZrN, TiN) instead of oxides in air is the special feature of the above mentioned experimental conditions. Nitride formation in air was defined by high temperatures and high burning rates during combustion of powdery Al, Ti and Zr.