Selected Pyrotechnic Publications of Dr. Takeo Shimizu,
Part 2 – Translated Articles
Titles and Abstracts (Part 2)
Introduction: The author attempts to establish a general theory summarizing the phenomena related to the chemical reactions occurring inside pyrotechnic compositions. There are three types of reactions: smoldering, burning and detonation. In addition, there are several interesting variations like sparking, flashing [strobing] and pyrotechnic whistling. These phenomena fall between smoldering and burning or between burning and explosion and should be referred to as “critical burning”. The theory must include these phenomena.
From Pyroteknikdagen, 1983
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Introduction: In recent years I have studied the oxidation and reduction taking place between various substances in a mixture. I reported on some of these studies in a paper titled “A Concept of Negative Explosives” presented in 1986 at the Eleventh International Pyrotechnics Seminar in Vail, Colorado, USA. In the present paper, I will be presenting the follow-up work which I have performed under the above title.
The work was carried out using the oxygen value of the mixture to clarify the burning effects. The oxygen value denotes the excess (positive) or inadequate (negative) amount of oxygen generated in grams per 100 grams of mixture during the burn.
The term “dark delay composition” refers to a mixture which does not form a flame or spark that is visible from a distance. The effect can be used to prevent the formation of the trail from a flying firework. It is referred to for short in the following as “dark composition”.
When a metal is used as the component of a mixture, a special effect is generated. A report is given here on metal sparks, red lead explosive charges and water flares. The metals in question are magnesium, magnalium, aluminum, ferrotitanium and zirconium, whose effects are explained as a function of the properties of the metal, those of the oxygen carrier and the oxygen value of the mixture.
From XVth International Pyrotechnics Congress held in Teneriffe, Canary Islands (Spain) 8 – 11 Nov. 1989
Please note that a typo in Table 3 on page 23 of the Dark Delay Compositions lists the first ingredient as potassium nitrate. It should state potassium perchlorate. This will be corrected in future printings.
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Summary: Those of us who work in the pyrotechnic industry have three requirements to obtain data concerning the sensitivity of mixtures: establish the starting point of no-ignition; understand the possibility of propagation of the ignition to combustion or explosion; clarify the variation of the sensitivity, which is dependent on the materials that we have used for tools. The methods used up to now have not satisfied our requirements.
The sensitivity was determined with a drop test using a steel ball onto a sample placed on an anvil. The sample used was molded as a thin round disk. This method was used to establish the propagation of ignition.
Initially, the experiment was conducted using the up-and-down method so as to compare with that described below. The data obtained on a salute composition did not indicate a normal probability distribution. This method does not give an exact result, without having some prior test data.
The experiment was then conducted using the descending-method, which I use regularly at the factory. The height of no-ignition was determined on 50 trials with the salute composition and with the composition CuO-Al.
It was possible determine the influence of the material of the anvil on the sensitivity of the mixture and substituting aluminum for the steel.
From EuroPyro 93, 5e Congrès International de Pyrotechnie du Groupe de Travail, 6-11 June, 1993
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Abstract: Black Powder is said to be the oldest explosive. At present, it is one of the most important explosives. However, the burning reaction mechanism of materials in the mixture is still obscure. The purpose of this study is to clarify this mechanism and illustrate some applications of Black Powder.
The burning reaction of Black Powder has been denoted for a long time by various formulae that include potassium carbonate or sulfate, which is found in the ash. The author has endeavored to clarify the formation of such materials during burning, in an effort to shed light on the burning reaction mechanism.
Through his experiments, the author found that potassium carbonate or sulfate is formed not only in the case of Black Powder, but also in the case of mixtures of potassium nitrate and charcoal or potassium nitrate and sulfur. It is clear that the formation of potassium carbonate or sulfate is not peculiar to Black Powder, but to nitrate.
The ash contains both of these substances. The formation reaction takes place not in a gaseous, but rather in a solid or liquid state. Such a reaction would explain the excellent ignition characteristics of Black Powder.
Other applications of the burning reaction mechanism of Black Powder could be found to make ignition of other compounds more effective.
From 26th International Annual Conference on Pyrotechnics, 1995
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Abstract: We conducted a small-scale experiment on soil simulating underwater blasting and studied the shape of waves as well as properties of electrical noises generated during blasting. From these noise waves, we wanted to detect any failure in initiation of the charge or blasting conditions, etc. It was observed that the main source of noise is the residual electricity in the exploder; the shape of noise waves is typical of blasting conditions of the charge. It enables us to detect blasting failure, or blasting of detonator touching the water, or detonation of charge, etc. from these noise waveforms. It was also confirmed that this method of detection can also be applied in double-hole or multi-hole blasting which follows stage explosion.
From Journal of the Industrial Explosives Society, Japan, Vol. 39 (1), 1978
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