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Kinetic analysis of foaming agent variants as a means towards optimised temperature cycles and foaming agent/matrix alloy combinations

Kinetische Analyse von Varianten von Schaumbildnern als Mittel für die Optimierung der Zyklustemperatur und Schaumstoff-Matrix-Legierungskombinationen
: Lehmhus, D.; Wichmann, M.; Busse, M.

Lefebvre, L.P.:
Porous metals and metallic foams, MetFoam 2007 : Proceedings of the Fifth International Conference on Porous Metals and Metallic Foams. September 5-7, 2007, Montreal, Canada
Lancaster, Pa.: DEStech Publications, 2008
ISBN: 978-1-932078-28-2
ISBN: 1-9320-7828-2
International Conference on Porous Metals and Metallic Foams (MetFoam) <5, 2007, Montreal>
Fraunhofer IFAM ()
Aluminiumlegierung; kinetische Reaktion; mathematisches Modell; Metallschaum; Temperatureinfluß; thermische Analyse; Titanhydrid; Zersetzungsreaktion; Aluminiumsiliciumlegierung

Different titanium hydride variants have been produced by means of thermal treatment in air. Thermal analysis data on these materials has been used for kinetic analyses comparing different kinetic models for the description of the decomposition reaction. Models based on Prout-Tompkins kinetic equations have finally been selected. For these, parameter values of the so-called kinetic triplet have been determined, allowing prediction of the course of the decomposition for arbitrary temperature cycles. These predictions are compared to measured data and the models thus justified. For a range of low-melting matrix alloys of the Al-Si-Cu-Zn type containing different foaming agent variants, foam expansion experiments have been performed during which time and temperature as well as volume expansion were recorded. AlSi7 has been included in the study as a reference material. For each combination of matrix alloy and foaming agent the foaming temperature and thus the temperature cycle endured by the precursor has been varied as an additional parameter. The resulting expansion curves have been matched with the prediction of the decomposition reaction for the respective temperature cycles derived from the initial kinetic analyses of the foaming agent variants, showing good agreement up to medium levels of expansion. As criterion for foam collapse, a limiting gas release rate is proposed. Based on such criteria on the one hand and kinetic analysis results on the other, temperature cycles giving tailored shapes of the degree of reaction-vs.-time/temperature curve and promising improved foam expansion can be defined.
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