Extraction of Ti Powder from Ti–MgO–Mg(–CaO) Cakes Produced by Magnesiothermic Reduction

The extraction of Ti powder from SHS-produced Ti–MgO–Mg(–CaO) cakes by treatment in leaching solutions (HNO₃, HCl, and NH₄Cl) was explored and optimized in relation to such factors as concentration of leaching agent, leaching temperature, chemical resistance of target Ti powder, and extent of byproducts extraction. The type of leaching solution was found to affect the size, structure, and morphology of resultant Ti powder. Best results were obtained at 70°C with aqueous solutions of: (1) the nitric acid taken in a 6-fold excess to the Mg content of combustion product and (2) the ammonium chloride taken in a 20-fold excess to nominal Mg content.     

Composition of the water-soluble humic preparations of mechanically activated brown coals

Conditions for the solid-phase mechanochemical activation of coals, which make it possible to substantially increase the yield of water-soluble humic preparations enriched in humic acids and mineral elements, are given in this work. It was found that the humic preparations isolated from mechanically activated coals are characterized by an increase in the antioxidant activity and a change in the cationic and anionic composition. The concentration of acidic ionogenic groups in humic acids increased.     

Ultrafine and nanosized MoSi2 powders by SHS process with a reduction stage

Suggested are basic principles for fabrication of fine MoSi₂ powders by SHS process with a reduction stage. Investigated was the influence of green composition, stoichiometric ratio, inert NaCl additive, and synthesis conditions on the structure/properties of thus fabricated MoSi₂ powders. With increasing amount of added NaCl, the mean size of MoSi₂ crystallites was found to decrease. The fabricated MoSi₂ powders represented the agglomerates formed by the crowds of smaller (200 nm) and larger (up to 1–3 μm) particles. The powders were characterized by SEM, XRD, and chemical analysis.     

Properties of vapor-deposited borophosphorosilicate glass layers employed in technology of silicon integrated circuits

The data of investigations on the physicochemical and electrophysical properties of borophosphosilicate glass layers deposited from mixtures of tetraethoxysilane and esters of boric and phosphoric acids in an oxygen-ozone medium (temperature, 400–440°C; atmospheric and subatmospheric pressures) have been generalized. The empirical relationships are obtained for determining the boundaries of the optimum dopant concentration region when the glass is used as a reflow interlayer dielectric in integrated circuit technology. The assumption is made that the structure of borophosphosilicate glass layers is formed by a porous network involving dopant clusters.     

Electrodeposition of Nanocrystalline Nickel Coatings from a Deep Eutectic Solvent with Water Addition

Protection of Metals and Physical Chemistry of Surfaces - The electrodeposition of nanocrystalline Ni coatings from electroplating baths containing deep eutectic solvents (analogues of...     

Processes of the Collision Interaction between Ceramic Particles Being Crushed in a Circulation Pneumatic Crusher

A new circulation pneumatic crusher capable of producing submicron powders of refractory materials is presented. A mathematical model is constructed for the dynamic breaking of ceramic macroparticles. This model allows the basic laws of shock-wave crushing in the circulation pneumatic apparatus to be analyzed.__________Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 3, 2005, pp. 327–333.Original Russian Text Copyright © 2005 by Belov, Biryukov, Roslyak, Yugov, Afanas’ev.     

Kinetics of the formation of supersaturated solid solutions upon mechanical alloying: II. Qualitative analysis of diffusion processes in interstitial solid solutions

Specific features of the kinetics of absorption of atoms of an alloying element by nanostructured alloys which lead to the formation of strongly supersaturated interstitial solid solutions upon plastic deformation of multiphase powder mixtures is discussed. The rate of absorption is shown to substantially depend on the parameters of mechanical action, segregation phenomena at the external and internal boundaries of the solid solution, and mechanisms of plastic deformation of the nanomaterials. Numerical estimates of the parameters that characterize the process of mechanical alloying of the powder mixture of iron with 25 at % carbon are given, which agree satisfactorily with the experimental data.