MODELING OF THE EFFECTS OF POROSITY AND PARTICLE-SIZE ON THE STEADY-STATE WAVE VELOCITY IN COMBUSTION SYNTHESIS

A simple model has been developed for steady-state combustion wave velocity which takes into account the effects of porosity, pore size and powder particle size. This model uses a unit-cell approximation for a characteristic porous compact geometry and also a description of heterogeneous reaction is utilized as an approximation to explicitly include the effect of particle size. Parametric studies indicate that as the porosity increases the combustion propagation rate decreases. It is also inferred that the pore size plays an important role in this behaviour and it can even reverse this trend at high values of pore size. As observed in combustion experiments, the model also correctly predicts the increase in combustion velocity with decreasing particle size.