The degradation of the nitrate oxidant was followed in the course of the aging process of tracer pyrotechnic mix containing 22.0 % Mg, 46.0 % Sr(NO3)2, 22.0 % KCIO4, 9.0 % Al‐Mg alloy and 4.0 % organic binder. The accelerated aging was conducted under the conditions of the increased humidity (98.5 %, 85.0 %, 78.5 %) at the increased temperature (75 °C). Nitrate content as a function of aging time was calculated by substracting nitrite nitrogen from total nitrogen content determined by Devarda's alloy reduction method. The degradation products of the nitrate (nitrite and carbonate) were determined by UV/VlS (Griess reaction) and IR spectroscopy, respectively. Nitrate proved to have a great instability in the presence of the metal, the extent of its conversion to nitrite and carbonate being rather great in comparision to the previously studied alkali metal nitrates in the presence of Mg as well. The loss of the nitrate and the formation of the nitrite and carbonate are governed by the same kinetic laws as fuel degradation to the hydroxide. The rate of the metal oxidation to the hydroxide was faster than the rate of the nitrate degradation process. The failure of the mix is connected to the rather small content of the nitrite (0.4 %) while the texture was significantly destroyed.

The aging of tracers, containing different amounts of Mg, Sr(NO3)2, KClO4, Al‐Mg alloy and organic binder, was conducted under the conditions of 50.0% and 98.5% relative humidities at 75 °C, and of 98.5% relative humidity at 25 °C. IR spectroscopy and X‐ray diffraction were used for investigation of chemical changes. At the lower humidity no detectable changes were observed. Tracer of metauoxidant ratio >1 exhibits decreased stability, changing significantly under the conditions of higher humidity, even at room temperature. In the reaction sequence of aging process (Mg(OH)2) and SrCO3 are formed, with concomitant decrease in Mg and Sr(NO3)2 content. Alloy changes only slightly, and the content of KClO4 and binder remains unchanged. Interaction between metal and nitrate is considered to be essential in the process of chemical aging.

The physical and chemical characteristics of green signal pyrotechnic mix, before and after destabilization caused by the action of increased humidity at different temperatures, were determined. Data obtained by the means of X‐ray diffraction. IR spectroscopy and adiabatic calorimetry were compared with the results acquired by measuring functional characteristics (the dominant wavelength and the colour hue of the emitted light, the intensity of the emission and the rate of burning). Comparision of all of these results points out to the very close relationship between the X‐ray diffraction data and the function of the signal mix. Chemical changes, leading to the disuse of the examinated mix, were recognized as Mg(OH)2, BaCO3 and Ba(NO2)2 formation with concomittant decrease in Mg and Ba(NO3)2 content. Since no changes were observed in separately aged components, the interaction among components proved to be of essential importance.

This work is a continuation of our former investigations in the field of corrosion of steel by alternating currents. In‐vestigations of corrosion of construction ship steels by alternating currents in seawater have been made. Investigations were performed within the range of alternating current densities from 20 up to 1500 mA/dm2 at frequencies from 18 up to 20000 Hz. Investigations have shown that the corrosion rate increases with the increase of current density at constant frequency. Besides, it has been established that at constant current density the corrosion rate decreases with the frequency increase up to 2000 Hz, and with the further increase of frequency up to 20000 Hz the rate of corrosion is increased. The material effect of corrosion by alternating currents in our investigations amount to 4.35–17.57% of the corrosion by equivalent densities of direct current.

The behaviour of six different types of binders phenol‐formaldehyde resin, shellac, polyvinylchloride, ethylcellulose, nitrocellulose, and fluorel was investigated in pyrotechnic compositions on the basis of magnesium, boron and aluminum. It has been found that the nature of the binder significantly influences the burning characteristics of the igniters. Correlation has been found between binder exothermicity and investigated characteristics. In addition, the influence of the contents of phenol‐formaldehyde resin and of fluorel, in the range of 0% to 25% on the same performance characteristics was studied. Phenol‐formaldehyde resin has been chosen as preferred binder for the investigated igniters in an amount of 5%.