Structure of low-carbon steel sheet after scale removal

The structural and phase changes in low-alloy steel during scale removal are analyzed by means of optical and transmission electron microscopy. A band with increased pearlite content is observed; it may be attributed to the liquation of carbon.     

Rail strengthening in prolonged operation

In rail operation (with traffic corresponding to passed tonnage of gross loads of 500 and 1000 million t), the surface layer of the steel is significantly strengthened. Electron-microscope data permit quantitative analysis of the contribution of different mechanisms to rail strengthening in prolonged operation, at different distances from the contact surface. The strengthening is multifactorial: it involves substructural strengthening associated with nanofragment formation; dispersional strengthening by carbide particles; the formation of atmospheres at dislocations; and polar stress due to interphase and intraphase boundaries. The significant increase in the surface strength of rail steel after prolonged operation (passed tonnage of gross loads of 1000 million t) is due to the presence of long-range internal stress fields and to the fragmentation of material with the formation of nanostructure.     

Gradient structural phase states formed in steel 08Kh18N10T in the course of high-cycle fatigue to failure

Optical and scanning and transmission electron microscopy have been used to study structural and phase states of steel 08Kh18N10T failed under fatigue conditions. Structural factors that reduce the fatigue life of a material have been revealed. To increase the fatigue life of the steel, it is recommended to treat the surface of the material by concentrated energy fluxes.     

Effect of the addition of ultrafine aluminum powders on the rheological properties and burning rate of energetic condensed systems

The effect of small additives (1.25–5.00%) of ultrafine aluminum powders (UFAP) on the rheology and combustion of model four-component energetic condensed systems is studied. It is found that the addition of UFAP decreases the temperature of HMX decomposition. Small additives of UFAP increase the burning rate of model energetic condensed systems and decrease the exponent ν in the burning rate law without deteriorating the rheological characteristics of the model propellants. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 1, pp. 54–59, January–February, 2007.     

Synthetic kenyaite as catalyst support for hydrocarbon combustion

Synthetic kenyaite is prepared in the system K₂O–SiO₂–H₂O. It is modified with cobalt and platinum in order to obtain catalysts for complete oxidation of n-hexane and benzene. The prepared samples are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TG), differential thermal analysis (DTA), temperature programmed reduction (TPR) and Fourier transformed infrared (FTIR) spectroscopy. Co is loaded on kenyaite using ammonia method and classical impregnation. Bimetallic Co–Pt possess higher catalytic activity than monometallic cobalt for the oxidation of benzene, while, for hexane oxidation, the monometallic cobalt catalysts exhibit higher or close activity to that of Co–Pt samples. The catalysts prepared by ammonia method have better performance due to finer dispersion of the metal particles on the surface of the support.     

Solving Problems in Ore Mining and Processing Using Information Technologies

Journal of Mining Science - Specificity of using information technologies to improve safety and efficiency of integrated mineral mining is described. The results of works on creation of information...     

Diopside – Mg orthosilicate and diopside – Ba disilicate glass–ceramics for sealing applications in SOFC: Sintering and chemical interactions studies

Diopside (CaMgSi₂O₆) based glasses compositions containing magnesium orthosilicate or barium aluminosilicates phases have been appraised for sealing applications in solid oxide fuel cells (SOFCs) and other solid-electrolyte devices. The sintering behavior and crystalline phase evolution of glass powders has been investigated under isothermal and non-isothermal conditions in the SOFC operating temperature range (800–900 °C). All the glass compositions exhibited two-stage shrinkage behavior resulting in well sintered and mechanically strong glass–ceramics with Augite as the primary crystalline phase. The appropriate coefficient of thermal expansion (CTE), long term thermal stability (300 h at 900 °C), high electrical resistivity, good adhesion and minimal reactivity with SOFC components makes the investigated glass–ceramics potential candidates for further experimentation as SOFC sealants.     

Specific features of the structure and properties of carbon nanocolumns formed by low-temperature chemical vapor deposition

The process of the formation of column-shaped carbon nanostructures by plasma-enhanced chemical vapor deposition is explored. Carbon nanocolumns are formed at 250°C. The structure and properties of the structures are studied by atomic-force microscopy, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The electrical properties of the structures are investigated.     

Temperature distribution produced by pulsed energy fluxes, with evaporation of the target

Thermal processes produced by pulsed energy fluxes are analyzed. The proposed model takes account of evaporation and melting of the target. The corresponding mathematical problem is formulated, with change in the type of boundary conditions. A numerical model is developed, as well as a computational program that does not require a fitting parameter. A formula for the dispersion time of the evaporating material is derived. Numerical values are obtained for the depth of melting as a function of the energy density. Options for parameterization of the experimental data are noted.