Interaction of Boron Carbide with Nickel Oxide

Thermodynamic methods and x-ray analysis have been applied to the chemical interactions in 0.9625 B₄C + 0.05 NiO + 0.0375 C, B₄C + NiO, B₄C + 4 NiO + 3 C mixtures; stages occur in the processes there that correspond to various temperature ranges. It is found that NiB always contains small amounts of lower borides, whose quantity does not exceed 2 mass% when the synthesis conditions are optimal.

     

Certain regularities of the kinetics of moisture and heat exchange in drying of moist materials

Methods of calculation of the kinetics of drying of moist materials for the period of the falling rate are considered; they are based on the characteristics of the kinetics of drying: the relative drying rate and the generalized and relative drying times. Miscellaneous  Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 6, pp. 1102–1110, November–December, 2008.     

Comparative Study of the Chemical Resistance of Titanium Nitride and Stainless Steel in Media of the Oral Cavity

We have shown that TiN powders practically do not react with biochemical media in the body. Using the polarization curve method, x-ray phase analysis, and Auger-electron spectroscopy of the electrode surface, we have studied the reaction of titanium nitride and 12Kh18N10T stainless steel with distilled water, a 3% solution of NaCl, HCl, and gastric juice. We have demonstrated the high corrosion resistance of both materials in H₂O (which is also typical for saliva); but in the presence of salt and when gastric juice is ejected from the esophagus into the oral cavity, the corrosion resistance of steel may decrease by several orders of magnitude compared with TiN. In the case of a titanium nitride electrode, we have also established the mechanism of the protective (inhibiting) action of organic reagents contained in the biochemical media, while stainless steel dissolves in gastric juice significantly more rapidly than in hydrochloric acid with the same pH 2.0.

     

Recursive tangential-angular operator as analyzer of synchronized chaos

A method for the quantitative analysis of the degree and parameters of synchronization of the chaotic oscillations in two coupled oscillators is proposed, which makes it possible to reveal a change in the structure of attractors. The proposed method is tested on a model system of two unidirectionally coupled logistic maps. It is shown that the method is robust with respect to both the presence of a low-intensity noise and a nonlinear distortion of the analyzed signal. Specific features of a rearranged structure of the attractor of a driven subsystem in the example under consideration have been studied.     

The corrosion fatigue strength of pumping rods

Tests have been done on steels 40, 20N2M, and ES (experimental steel) for stress corrosion cracking (SCC) in various media (NACE medium, 3% NaCl solution, and chloride-calcium stratal water containing hydrogen sulfide).     

Reaction of aluminum nitride powder with biochemical media

The effect of particle size and morphology on the degree of dissolution of commercial AlN powder, fiber crystals, and nanoparticles in physiological solution, blood serum, gastric juice, and control media with the same values of pH was determined. The reaction mechanism of AlN powder with biochemical media and its toxic effect are discussed. Translated from Poroshkovaya Metallurgiya, Nos. 3/4(412), pp. 53–61, March–April, 2000.     

Features of (Ti, Me)C solid solution formation

The structure and phase composition of the products of combined carbothermal reduction of titanium and niobium (tantalum) oxides with an excess of carbon are studied. It is established that formation of solid solutions (Ti, Nb)C and (Ti, Ta)C occurs through successive stages of synthesis of the individual carbides followed by dissolution of TiC in NbC (TaC). Excess of carbon provides high dispersion of the reduction products and their purity with respect to oxygen. Features of solid solution (Ti, Nb)C formation with interaction of niobium oxide and titanium carbide with an excess of carbon (12 mass%) are studied. Use of fine-grained titanium carbide, pure with respect to oxygen, with excess carbon made it possible to reduce by 300 °C the temperature for forming homogenous solid solution and to obtain powder with a particle size of less than 8 μm without grinding. __________ Translated from Poroshkovaya Metallurgiya, Nos. 1–22(447), pp. 19–25, January–February, 2006.     

Using atomic-step-structured 6H-SiC(0001) surfaces for the calibration of nanotranslations in scanning probe microscopy

The silicon surfaces of 6H-SiC(0001) single crystals subjected to stepwise high-temperature annealing in vacuum have been studied by atomic force microscopy and scanning tunneling microscopy techniques. A special annealing procedure is proposed that yields a structured surface featuring regular atomicsmooth steps with heights of 0.75 and 1.5 nm. We propose using these structured crystal surfaces for calibrating vertical translations in scanning probe microscopes.