| || Effect of Surface Microstructure on the Temperature sensitivity of Burning Rate of Ammonium Perchlorate
Author : Sridhara, K. ;Kishore, K.
Source : Defence Science Journal ; Vol:47(2) ; 1997 ; pp 177-184
Subject : 66 Chemical Technology
Keywords : Thermodynamics ;Vielle law
Abstract : Considering Vielle's law and the new thermodynamic model which the authors have developed recently the true dependence of temperature sensitivity of burning rate of ammonium perchlorate (AP) on pressure is resolved and experimentally verified for bellet burning. The value of decreases with pressure steeply in regime I' (below 20 atm), but gently in regime I (above 20 atm). The value of powder AP has been determined and it is observed that (powder) > (pellet), which clearly suggests that of is innuenced by the surface temperature sensitive parameter and hence by the surface/subsurface microstructure. In powder burning, the buoyant lifting of the particles into the gas phase occurs, which constitutes the so-called 'free board region' (FER) extending just above the true surface. Consequent to the decomposition of AP particles in FER, the condensed phase heat release gets curtailed and (powder) becomes larger. A general relationship for in terms of density and surface temperature is suggested, which is applicable to both pellet and powder AP.