Solid phase redox reactions are characterized by the exchange of oxygen betweenparticles of metals and solid oxides. The reaction velocity is controlled by thefuel/oxidizer ratio and the particle size which influences the contact area andhomogeneity of the dispersion. To model this type of reaction mainly thermodynamicapproaches are in use which only allow limited conclusions to reaction velocity andphysico-chemical reaction mechanisms. To describe particle reactions with heat andmass transfer a transient, 3-D model is developed using the heat flow and diffusionequation in combination with hot-spots both as energy sources and as material sources.An approach based on the Green's function is used to solve the equations. Theadvantage of the procedure is that the physical/chemical nature of the process is alwaysobvious as well as occurring stability problems. In addition, complex geometrical 3-Dconfigurations are accessible at transient conditions because of the effectiveness of theapproach. To validate this modeling thermite-like mixtures of Zr with Fe2O3 have beenprepared using different fuel/oxidizer ratios (lean, stoichiometric and fat) and particlesizes including nano-particles. The reaction temperature was determined using fastNIR-spectrometer assuming grey body spectra. The results are discussed in comparisonto the modeling calculation.
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