Energy intensity of a clean break

Institute of Mining, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 114–118, January–February, 1989.     

The optical absorption of solid fractal structures in silicon carbide

The silicon carbide particles with solid fractal formed in an electric arc discharge plasma exhibit anomalous optical properties. In the 360–475 nm wavelength range, the level of light absorption in the fractal structures of silicon carbide is 15–30 times that in single-crystalline SiC samples.     

The role of nitrogen atoms in forming the carbon structure in the carbonization of polymer composites

Data have been used from X-ray photoelectron spectroscopy, small-angle X-ray spectroscopy, nuclear magnetic resonance, IR Fourier spectroscopy, electron spectroscopy, and other current methods for polyacrylonitrile, polypyromellitimide, hydrated cellulose, hard coals, and various model compounds to examine the effects of the nitrogen atoms on carbonization and graphitization. The nitrogen atoms are found to have multiple effects on the thermochemical and thermophysical parameters of the polymer carbonization over a wide temperature range. In the derivation of the carbon structures, the nitrogen acts as a messenger combined agent, which gives rise to heterorings, which are transformed into intermediate aromatic compounds, which form the basis of the matrix synthesis consisting of ordered graphite-type structures. Translated from Khimicheskie Volokna, No. 4, pp. 53–61, July–August, 2008.     

Crystal structure of the new ternary aluminide CeRu3−xAl10+x (x = 0.17)

A large and transparent Yb³⁺:GdYCOB crystal with dimensions up to 30 mm× 58 mm have been grown by the Czochralski method. The spectral properties of Yb³⁺:GdYCOB crystal has been investigated. The absorption cross-section (σ_a) is 1.65 × 10⁻²⁰ cm² at 977 nm. The emission cross-section (σ_e) is 0.25 × 10⁻²⁰ cm² with an FWHM of 37.2 nm at 1020 nm. The fluorescence lifetime is 3.00 ms.     

<Emphasis Type="Italic">L</Emphasis><Subscript>3</Subscript>-XANES spectroscopy of the valence-unstable cerium in intermetallic compounds with 3<Emphasis Type="Italic">d</Emphasis> metals

The effective valence of cerium is studied by L ₃-XANES spectroscopy using synchrotron radiation in the following valence-unstable systems with different types of magnetic ordering: a CeNi matrix doped with neodymium, praseodymium, and gadolinium ions in the temperature range 5–300 K and the Ce₂Fe1_{7 − x} Mn _x intermetallic compound. The obtained dependences are discussed in terms of generally accepted models of states with an intermediate valence of rare-earth ions. Possible correlations between the effective valence of cerium and the magnetic properties of the substances are taken into account.     

Thermostable fibres and the carbon-fibre-reinforced plastics made from them

The specific features of creation of highly thermostable composite materials based on thermostable fillers and binders are examined. There has been some progress in synthesis, modification, and pilot-industrial production of polyimides that satisfy the many-sided requirements of the 21st century. The possibility of assigning products of thermochemical reactions of polymers based on polyacrylonitrile to thermostable organic compounds capable of modifying thermostable binders is discussed. The necessity of theoretical studies of modeling the thermal transformations of the initial products in composite mixtures is demonstrated. The necessity of structural orientation of macrochains of the reacting components for realization of the cocarbonization principle is substantiated. __________ Translated from Khimicheskie Volokna, No. 2, pp. 26–33, March–April, 2007.     

Structure formation in high-speed spinning of polyethylene terephthalate

Conclusions Commonness and differences in yarn structure formation by high-temperature and low-temperature stretching have been shown.Model concepts on the development of structure in high-temperature deformation during the process of high-speed yarn spinning have been examined.It has been found that, on changing the linear density of elementary filaments, the spinning speed, or the position of the lubricating device, the proportion of effective high-temperature and low-temperature deformations changes.Translated from Khimicheskie Volokna, No. 3, pp. 16–19, May–June, 1988.