Effects of some factors on centrifugal casting of oxide ceramics

Conclusions It is shown that in technically suitable conditions for shaping blanks by centrifugal casting, the deposition of the particles occurs with a streamline schedule, and the coarse fractions are deposited during acceleration of the rotation of the mold. The main factor influencing the density of the finely dispersed blanks is the duration of rotation, and for systems containing coarse filler, centrifugal acceleration. Regulating the dimensions (wall thickness) of the blank is possible by altering the concentration of solid phase in the slip and the degree of filling of the mold with it.Translated from Ogneupory, No. 1, pp. 22–24, January, 1992.     

Thermochemical processing of high-sulfur Israeli shale

The thermochemical processing of high-sulfur shale from the Mishor Rotem deposit (Israel) is studied in terms of the material balance, in a Fisher retort and a larger-scale laboratory system. The properties of the products (tar, char, and gas) are determined. The shale tar has a high sulfur content, on account of the presence of a wide range of thiophene derivatives. In the fractions of semicoking tar from Mishor Rotem shale that boil at temperatures up to 250°C, 236 compounds are quantitatively identified. The content of thiophene and its homologs with the substituents C₁–C₅ and of benzothiophene with alkyl substituents C₁–C₃ is determined.     

Disordering of Pentacesium Trihydrogen Tetrasulfate in Cs5H3(SO4)4–SiO2 Composite Proton Electrolytes

(1 – x)Cs₅H₃(SO₄)₄ · yH₂O–xSiO₂ composite electrolytes were prepared in the composition range x = 0.3–0.9 and were characterized by impedance measurements, differential scanning calorimetry, and x-ray diffraction analysis. The results indicate that the introduction of fine SiO₂ particles stabilizes the high-conductivity, disordered (nearly amorphous) state of the salt, which is similar to that in pure Cs₅H₃(SO₄)₄ above the phase transition (>420 K). The conductivity of the composites is independent of SiO₂ content up to x = 0.7 and decreases at x 0.8 owing to percolation disruption. The disordering of Cs₅H₃(SO₄)₄ · yH₂O is reversible and is due to changes in the content of water of hydration.     

Determining the degree of coal oxidation at PAO AKKhZ

Methods of assessing coal oxidation are compared. The method developed by the Soviet Institute of Mining and the Coal Chemistry Institute is most expedient. On that basis, a draft of the Ukrainian DSTU standard on determining the oxidation of coal has been formulated. The method has been successfully used in selecting the flotation agent for coal enrichment at PAO Avdeevskii Koksokhimicheskii Zavod (AKKhZ).     

Production of superhard railroad wheels from T steel

The production of superstrong and durable heat-treated railroad wheels fromT steel is considered. Aspects of heat treatment are described, and the macrostructure, microstructure, and mechanical properties of the wheels are investigated.     

Investigation of Cs(H2PO4)1 − x (HSO4) x (x = 0.15–0.3) superprotonic phase stability

A detailed investigation of the highly conductive Cs(H₂PO₄)_1?x (HSO₄) _x (x = 0.15–0.3) proton electrolyte, its structural properties, and ageing behavior was carried out using X-ray diffraction, DSC, and impedance and NMR spectroscopy. The high conductivity of electrolytes (～2 × 10^?2 S/cm) remains stable during long-term ageing at 180–200°C due to stabilization of the high temperature phase to lower temperatures. The room temperature ¹H MAS NMR spectrum of (CsH₂PO₄)_1?x (CsHSO₄) _x demonstrates the predominantly highly mobile protons present in these materials with the residual low-mobile protons, which agrees with the XRD data. According to XRD and ¹H NMR data, the cubic phase of Cs(H₂PO₄)_{1 ? x} (HSO₄) _x (x = 0.15–0.3) that stabilizes at room temperature gradually transforms to a low-temperature monoclinic one. The kinetics of the phase transformation for mixed salt depends markedly on the relative air humidity. A possible stabilization mechanism of the Cs(H₂PO₄)_{1 ? x} (HSO₄) _x superionic phase with high proton mobility at low temperatures is discussed.