Titanium oxidation kinetics and the mechanism for thermal ignition of titanium-based pyrotechnics
Previously published experimental studies proposed that thermal ignition of titanium-based pyrotechnics is controlled by the rate at which an initial oxide coating dissolves into the bulk metal as a result of molecular diffusion. The proposed dissolution mechanism was based primarily on the exotherms and ignition temperatures, which were about 793/sup 0/K, observed using differential thermal methods involving heating rates of 0.33 K/s. Data from a more recent investigation of titanium oxidation kinetics at temperatures between 473 and 773/sup 0/K showed that, for time scales on the order of minutes and temperatures near 773/sup 0/K, titanium oxidation rates and, therefore, pyrotechnic ignition are determined by diffusion-controlled growth of a TiO/sub 2/ (rutile) layer adjacent to the gas-solid interface. They are not controlled by oxygen dissolution into the bulk metal. This result was based primarily on Auger depth profiles from isothermally oxidized titanium single crystals. It is further supported by the present work, in which a model for pyrotechnic response during differential thermal analysis experiments was derived using an oxidation rate expression based on growth of a TiO/sub 2/ layer. The model predicts exotherms which are consistent with those reported in the previously published experimental studies. 16 refs., 4 figs., 3 tabs.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5816049
- Report Number(s):
- SAND-85-2872C; CONF-860739-6; ON: DE86010987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201 -- Chemical & Physicochemical Properties
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DIFFERENTIAL THERMAL ANALYSIS
DIFFUSION
ELEMENTS
FICK LAWS
HIGH TEMPERATURE
HYDRIDES
HYDROGEN COMPOUNDS
IGNITION
KINETICS
MATERIALS
MATHEMATICAL MODELS
METALS
MINERALS
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PYROTECHNIC DEVICES
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
REACTION KINETICS
RUTILE
THERMAL ANALYSIS
TITANIUM
TITANIUM COMPOUNDS
TITANIUM HYDRIDES
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS