Hydrodemercaptanization as an Optimal Means of Producing Jet Fuel: Comparison with Hydrotreating and Oxidative Demercaptanization

Chemistry and Technology of Fuels and Oils - The article presents a comprehensive analysis and comparison of existing technologies for producing jet fuels: hydrotreating, hydrodemercaptanization,...     

Effect of preliminary and repeated heat treatment on the plasticity and structure of 25Kh17N2B-Sh steel

An investigation of prematurely damaged high-pressure pipelines from steel 25Kh17N2B-Sh showed that the microstructure of their parts contains a carbide network and coarse austenite grains, which are known to worsen the mechanical properties. The possibility of improving the structure and plasticity of parts of high-pressure pipelines from martensitic steel 25Kh17N2B-Sh by preliminary quenching with subsequent subcritical tempering or cyclic heat treatment before final vacuum quenching is discussed below, The capacity for grain growth in the quenching of parts from rods of different heats and the effect of double quenching to improve the coarse-grain structure are investigated.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 9–11, August, 1995.     

The structural state of ultrahigh-molecular-weight polyethylene in single-stage arc-discharge plasma deposition of nanoparticles

We present the results of a study of the structural state of ultrahigh-molecular-weight polyethylene (morphology, X-ray-diffraction patterns, IR spectra) obtained in a single technological cycle combining the synthesis of nanoparticles and their deposition onto the surface of polymer microgranules. Technological conditions for the preservation of the initial state of ultrahigh-molecular-weight polyethylene are found for its presence in the zone of thermal action of the plasma flow. Mechanisms of degradation of the polymer are discussed.     

Problem of unexpected failure of steel parts

Examples of unexpected (brittle) fracture that occurs in the production of parts or the operation of parts and machines despite of the fact that the mechanical properties of the metal (steel) satisfy the standards for metal products are considered. Solutions to the problem are suggested on the basis of earlier works of the author. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 31–34, March, 1998.     

Electrically Conducting Ceramics Based on Al–AlN–TiB<Subscript>2</Subscript>

The high-temperature conductivity of ceramics based on Al–AlN–TiB₂ obtained by self-propagating high-temperature synthesis has been studied. The dependences of DC resistivity were measured in vacuum (1 Pa) by a four-point technique in a temperature range of 293–1273 K. The evolution of the phase composition of the material upon heating was studied by time-resolved diffraction in real-time mode. The measurements show a “metallic” behavior of conductivity when the Al–AlN–TiB₂ composite is heated, and there is also an abrupt change of resistivity in a temperature range of 870–970 K that is linked with Al melting. In this case, the crystalline structure of ceramic phases does not undergo changes in the studied temperature range. The same temperature coefficient of resistance has been observed for all studied compositions up to the melting point of aluminum.     

Specific Features of Application of Different Methods of Analytical Control of Spent Catalysts of the Petrochemical Industry

A method of analysis of samples of spent petrochemical catalysts based on acidic decomposition of samples with further determination of platinum by inductively coupled plasma mass spectrometry is developed. The method allows analyzing various brands of catalysts, mixtures, and waste of catalysts formed during regeneration. A comparative study of the results of platinum determination obtained by different analytical methods in samples of several types of catalysts is performed. It is shown that spectrophotometric method of platinum determination in spent alumo-platinum catalysts recommended for certification of batches of catalysts and umpire analysis is not universal. At comparable accuracy indices, the analytical method should be selected taking into account the specific features of a particular batch of catalysts and restrictions of the applied method.