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this system.Thus it is possible to compare thedata collectedacross a largenumberof experi-
mental conditions togivemorecompleteunderstandingof thisgasless reaction.Althoughthis
systemhas been extensively studied for over 40 years now, a consensus has not emerged on
the exact activationenergy, as canbe seen inFigure9. Thedata again illustrate the effect that
differing experimental conditions play, whether in the material structure, heating rates, or
otherexperimental factors.
In1987,Philpotet al.didpreliminarystudieson theNi/Al systemkineticsusing theKissinger
approach [35]. They showed that there is an effect of heating rate, the nickel particle size, as
well as an effect of a varyingAl content, on the reactionmechanism in this system [35], this
work is highlighted in more detail in an above section. Hunt et al. examined the effect of
particlesizeontheapparentactivationenergyusingaCO2laser tocontrol theheatingcoupled
with theDTA-basedKissinger approach.Using800nmsizeNiparticles coupledwith20μm,
4μm, 80 nm, and 40 nmAl particles, it was found that that these reactions had activation
energies of: 103.5 10.5, 97.3 5, 21.2 2.5, and 17.4 2.85 kJ/mol, respectively [36]. They
then increased the Ni size to 15 μm and measured with the four Al sizes, resulting in
162.5 1.4,131.2 2.6,103.6 5.2,and80.1 6.3kJ/mol, respectively [36].Thisconfirmsthat
the initial reactant structure plays a significant impact on the kinetics. The size of either
reactant significantly alters the effective kinetics. Kim et al. studied this reaction using
nanolaminated composite micro-foils with different thickness ratios between Ni and Al at
heating rates between 5 and 100K/min. For 4:1 foils, they found that the formation ofNiAl3
occurred, followedbyNi2Al3,withactivationenergiesof142and106kJ/mol, respectively [37].
Figure9. Summaryofkineticdatacollected for theNi/Al system.
Kinetics of Heterogeneous Self-Propagating High-Temperature Reactions
http://dx.doi.org/10.5772/intechopen.70560 181
zurück zum
Buch Advanced Chemical Kinetics"
Advanced Chemical Kinetics
- Titel
- Advanced Chemical Kinetics
- Autor
- Muhammad Akhyar Farrukh
- Herausgeber
- InTech
- Ort
- Rijeka
- Datum
- 2018
- Sprache
- englisch
- Lizenz
- CC BY 4.0
- ISBN
- 978-953-51-3816-7
- Abmessungen
- 18.0 x 26.0 cm
- Seiten
- 226
- Schlagwörter
- Engineering and Technology, Chemistry, Physical Chemistry, Chemical Kinetics
- Kategorien
- Naturwissenschaften Chemie