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On the Mechanisms of Titanium Particle Reactions in O 2 /N 2 and O 2 /Ar Atmospheres
Author(s) -
Andrzejak Timothy A.,
Shafirovich Evgeny,
Varma Arvind
Publication year - 2009
Publication title -
propellants, explosives, pyrotechnics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.56
H-Index - 65
eISSN - 1521-4087
pISSN - 0721-3115
DOI - 10.1002/prep.200700256
Subject(s) - quenching (fluorescence) , combustion , particle (ecology) , materials science , titanium , liquid nitrogen , analytical chemistry (journal) , melting point , thermocouple , nitrogen , chemical reaction , chemical engineering , chemistry , metallurgy , organic chemistry , composite material , physics , oceanography , quantum mechanics , engineering , fluorescence , geology
Combustion of titanium particles in air may potentially be used for the in situ synthesis of nanoscale TiO 2 particles, which can photocatalytically degrade chemical and biological air pollutants. The knowledge of Ti particle reactions in O 2 ‐containing atmospheres is required to develop this method. In the present work, large (∼3 mm) single Ti particles were heated by a laser in O 2 /N 2 and O 2 /Ar environments. High‐speed digital video recording, thermocouple measurements and quenching at different stages of the process were used for diagnostics. Analysis of the obtained temperature‐time curves and quenched particles does not show a significant influence of nitrogen on the oxidation of solid Ti. In all experiments, noticeable surface oxidation started at temperatures between ∼850 and ∼950 °C, leading to a sharp temperature rise at ∼1400 °C. During prolonged heating at the Ti melting point (1670 °C), a liquid TiO 2 bead formed and, after an induction period, ejected fragments. It was shown that this phenomenon may result from an excess of oxygen in the liquid bead. Fragment ejection in O 2 /N 2 atmospheres was more intense than in O 2 /Ar, indicating that N 2 accelerates the oxidation of liquid Ti.