Synthesis, characterization and catalytic application for wet oxidation of phenol of iron-containing clays

High-surface-area pillared clays (PILC) were prepared from naturally occurring montmorillonites by exchanging interlayer ions to polyoxocations containing (i) aluminum (Al₁₃-PILC), (ii) iron adsorpted onto Al₁₃-PILC, and (iii) iron and aluminum located within the same complex (Fe_0.8Al_12.2-PILC). The obtained Fe_0.8Al_12.2-PILCs were characterized by DR–UV–vis and IR spectroscopy, XRD, ESR, scanning electron microscopy and low temperature N₂ adsorption measurements. Important factors affecting catalyst activity and phenol removal efficiencies have been studied, i.e. the effect of pH, temperature, catalyst concentration and stability of the catalyst.     

Mechanical activation of the reactive sintering of titanium carbide

This paper describes the mechanical alloying of Ti and C powders by intensive grinding in a planetary mill. The effect of milling conditions and initial composition on the compositional homogeneity and properties of powders and samples consolidated by hot-pressing was studied by x-ray diffraction, scanning electron microscopy, and surface area measurement. The diffraction patterns indicated that a powder mixture ground for 24 hours transforms to TiC after sintering for only one minute at 600°C under a pressure of 3 GPa. Materials Science Instiute, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 5–6, pp. 32–38, May–June, 1998.     

Some features of the formation of A1N during the reduction-nitriding of ultrafinely divided alumina

Conclusions A study was made of the process of carbothermic reduction-nitriding of ultrafinely divided alumina in the temperature range 1200–1450C. It was established that the carbothermic reduction-nitriding of ultrafinely divided alumina is accompanied by the formation of intermediate oxycarbide and oxynitride phases. This is a result of the alumina reduction process having a stepwise character and of the formation of solid solutions in the AI-O-N system. It is shown that the resultant aluminum nitride is in the form of polycrystalline particles. The sizes of the particles and of the grains in them are 1–3 and 0.01–0.2 m, respectively. With rise in nitriding temperature, the particles decrease and the grains increase in size.Translated from Poroshkovaya Metallurgiya, No. 11(263), pp. 14–19, November, 1984.     

Formation of silicon nitride from silica

Conclusions The formation of Si₃N₄, during the carbothermic reduction of SiO₂ in the presence of small Fe additions combined with nitridation is a complex process involving several solid-solid, gas-solid, gas-liquid-solid, and gas-gas reaction stages. The catalytic action of iron manifests itself in the formation of an intermediate compound — iron carbosilicide. The product of the nitridation of FeSi_xC_y is-Si₃N₄, and that of the nitridation of silicon, -Si₃N₄.Translated from Poroshkovaya Metallurgiya, No. 7(247), pp. 13–17, July, 1983.     

Development of a rational roll pass design for a rolling mill using performance criteria

A new technique is developed to analyze the roll pass design of a section rolling mill. Metal forming nonuniformity and efficiency coefficients, which determine the degree of working of a metal microstructure in rolling of section bars, are used as performance criteria. The system of roll passes intended for the production of a round bar 28 mm in diameter is used as an example to analyze possible deformation schemes and the advantages and disadvantages of each scheme.     

Synthesis of exfoliated graphite and its use as an electrode in supercapacitors

In this work, the effect of the synthesis conditions on exfoliated graphite and its properties was investigated. Exfoliated graphite was obtained via thermal reduction of graphite oxide at temperatures of 250–350°C. The influence of the synthesis conditions (temperature and heating rate) on the properties of exfoliated graphite (product yield, bulk density, specific surface area, specific capacitance and others) was determined via direct experimental design method. The ability to use exfoliated graphite in supercapacitors was determined on the basis of the specific capacitance data. The highest specific capacitance of exfoliated graphite was found to be 129 F/g.