Electromagnetic radiation shielding composite coatings based on powdered alumina and ironoxide

The article presents the results of experimental substantiation of the method for improving the shielding properties of composite coatings based on powdered alumina (electrocorundum, alum earth), which consists in modifying the composition of such coatings by adding to it powdered iron oxide. This experimental substantiation consisted in the development of the technique for obtaining composite coatings based on powdered alumina and iron oxide, the manufacture of the experimental samplesusing the developed technique, measurements of electromagnetic radiation reflection and transmission coefficients values in the frequency range 0.7…17.0 GHz of the manufactured samples; implementation of the comparative analysis of the measured values with the similar values typical for the composite coatings filled with powdered alumina oxides, and composite coatings with the fillers such as powdered iron oxide. The obtained results revealed that by adding powdered iron oxide to the composite coatings based on powdered alumina oxides, it is possible to reduce by 1.0…8.0 dB their electromagnetic radiation transmission coefficient values in the frequency range 0.7…17.0 GHz. In addition, we found that the implementation of the proposed method allows one to decrease by 2.0…20.0 dB the electromagnetic radiation reflection coefficient values in the specified frequency range of the considered composite coatings, if such are applied to metal substrates. We propose to use the composite coatings, obtained on the base of the substantiated method, in order to ensure the electromagnetic compatibility of radio-electronic equipment.

Ecologically closed energymetallurgical technology of powdered iron ore and coal-cleaning wastes processing

The problem of coal-cleaning wastes utilization is actual in many countries of the world. At present in Russia these wastes are used only at 10–15% in different industries, but the potential of their utilization is much wider. Peculiarities of waste-less technology of powdered coal-cleaning wastes gasification in the slag suspended layer considered, resulted in conditional synthesis gas obtaining with simultaneous reducing and isolation of metal from ash and slag. Besides, another result was obtaining a highporous alumina-silicate slag (microspheres), applicable as a light filler for paints and coatings with low heat conductivity, as well as absorbing agent etc. It was shown, that based on the earlier elaborated jet-emulsion facility, a waste-less technology of gasification (processing) of coal and its cleaning wastes can be created resulting in obtaining three liquid products: synthesis gas (or electric power), alumina-silicate micro granules and iron with dissolved in it rare metals. Apart from the wastes of coal-cleaning availability, the presence of powdered iron-containing wastes (dust from gas-cleaning systems, iron ore concentration tails) can increase the efficiency of the technology. The increase will take place due to stable gas-slag emulsion support and the two-phase flow in the connection channels, as well as decrease of gaseous oxygen consumption at the expense of it substitution by oxygen of iron oxides.

Influence of modifcation on the refinement of primary silicon crystals in hypereutectic silumin AlSi21CuNi

On the paper the influence of modifying micro additives on the refinement of primary silicon crystals in the hypereutectic AlSi21CuNi piston silumin have been examined. As the modifiers there were used micro additives of Phosphorus in the form of AlCu19P1.4 and CuP12 pre-alloys, sulfur in the form of CuS and iron in the powdered form. The modifying micro additives were used separately and together. Micro additions of iron were used together with phosphorus. Sulfur micro addition provided the fragmentation of the primary silicon crystals, but not as effective as the phosphorus micro additive. The best effect of fragmentation of the primary silicon crystals was ensured by the combined addition of phosphorus in the form of AlCu19P1,4 pre alloy with a micro additive of powdered iron which reduced the average size of the primary silicon crystals from 114 μm to 20 μm.