Determination of the Thermal Diffusivity of a Zr/PbCrO4 Pyrotechnical Mixture and of the arrhenius parameters of the ignition reaction in presence of an oxidizing atmosphere

An experimental device with main features closely related to those of Cook-Off type⁽¹⁾ devices has been developed to attain the specific study requirements. The tested product is a pyrotechnical compound containing zirconium and lead chromate in the proportion of 60% Zr and 40% PbCrO₄. An iterative calculation method has been developed to determine thermal diffusivity without any reaction and to evaluate the Arrhenius kinetic parameters of the product ignition reaction. The Zr/PbCrO₄ compounds appear as cylindrical tablets dia. 14 mm and 11.7 mm high. From room temperature to about 100°C, thermal diffusivity ranges between 3.2 and 3.9. 10⁷ m²/s. The ignition reaction kinetic parameters in an oxidizing atmosphere are as follows: Ea = 47 kJ/mol and Z = 10 · s⁻¹. With the results from thermal analysis, we demonstrate that initiation can be attributed to the oxygen contained in air, which diffuses into the product porosities. Lead chromate behaves as an inert substance throughout the ignition phase.