Science and Technology of Energetic Materials

Vol.65, No.1 (2004)

Research paper

Synthesis of transition metal picrates
Makoto Matsukawa, Takehiro Matsunaga, Masatake Yoshida, and Shuzo Fujiwara


Picric acid is known to react with metals to form highly unstable metallic picrates, which are known to have been involved in serious explosive accidents. In this study, transition-metal picrates of chromium, manganese, cobalt and nickel salts are synthesized, and the thermodynamic and explosive properties (for example, initiation sensitivity) are examined.

The decomposition of Mn-picrate or Co-picrate determined through differential scanning calorimetry (DSC) begins at a lower temperature than that of picric acid, and the heat of decomposition of transition-metal picrates is found to be lower than that of picric acid. Thermogravimetry and Karl Fischer analysis confirm that transition-metal picrates contain crystal water, and the amount of crystal water in metastable-phase picrates is determined experimentally. Thermogravimetric analysis reveals that crystal water begins to dehydrate in a temperature range extending from slightly above room temperature to approximately 470 K. The activation energies of the decomposition reaction of these transition-metal picrates are 204.1 kJmol-1 for Cr-picrate, 108.1 kJmol-1 for Mn-picrate, 132.3 kJmol-1 for Co-picrate, and 184.3 kJmol-1 for Ni-picrate. Drop-hammer test results show that Cr-picrate has higher strike sensitivity than picric acid, and friction tests reveal that all of the transition metal-picrates examined here have equal or lower friction sensitivity compared to picric acid.

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