The Effect of Halogenated Hydrocarbons on the Burning of Uranium and Zirconium

It has been found that the addition of several percent of any of a score of halogenated hydrocarbons to air in which uranium or zirconium foil is burning will markedly lower both the burning propagation velocity and the maximum burning temperature. For example, the addition of 2% CH₃C1 will lower the burning propagation velocity of 0.013 × 0.3 cm uranium foil from 0.52 to 0.41 cm/sec; the maximum burning temperature is lowered from 1375 to 1225°C. The use of 2% CH3CHF2 prevented burning from progressing along the entire length of this foil. For combustion of 0.002 × 0.3 cm zirconium foil, CF₂BrCF₂Br, CF₃Cl, and CF₃Br were found to be effective inhibiting agents. Because of the flammability of CH₃CHF₂, measurements were made of the effect of several halogenated agents on the flammability limits of that compound. It was found for example, that a 1:1 mixture of CH₃CHF₂ and CF₃Cl was nonflammable and effectively inhibited burning propagation of the uranium foil used in this study. Measurements with the uranium foil showed chlorine and bromine containing compounds to lower significantly the metal ignition temperature. That the halogenated agents may have opposite effects on ignition and steady combustion is a reflection of the difference in the controlling factors in the two cases.