Science and Technology of Energetic Materials

Vol.62, No.5 (2001)

Research paper

Thermal behavior of the mixtures of potassium benzoate with potassium perchlorate
(Study on pyrotechnic whistling noise)(*in Japanese)
Koki Ishikawa, Michio Koga, Masaru Matsumoto, Toshiaki Tsuru,
and Shun-ichi Yoshinaga


The mixtures of potassium salt of aromatic compounds such as benzoic acid, terephthalic acid and salicylic acid and potassium perchlorate were widely used as a pyrotechnic whistle composition.
In this report, the reactions of pyrotechnic whistle compositions of the mixtures of potassium benzoate with potassium perchlorate were investigated by thermal analysis, observation by microscope and sound test such as the waveform, frequency and sound pressure analysis of the whistling noise for different compositions, tube length and material of tube. The results obtained are as follows :
(1)The compositions capable for producing whistling noise are the mixtures of potassium benzoate with potassium perchlorate which compositions are in the proportions 40 / 60, 30 / 70, and 20 / 80 (C6H5COOK / KClO4 by wt.).
(2)The fundamental frequency of the pyrotechnic whistling noise is about 2 kHz, and harmonic sound appears beside the fundamental sound. The frequency is inversely proportional to the length of tube. Therefore, whistling noise was considered to appear by the resonance of the tube.
(3)Although different materials were used for the tubes, they made little difference in frequency and linear burning rate, when whistling compositions pressed into the aluminum, glass, and vinyl chloride tube. The sound pressure increases about 10 dB louder cmpared to that one which pressed into the paper tube.

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