Influence of the properties of an oxide film on the oxidation of aluminium powders

The structure of oxide films of aluminium powders has been established to depend on the size of its particles. The temperature dependence of the oxidation of the powder in air is ascribed to changes in both the structure of the oxide laver and the pressure of saturated aluminium vapor. The porous, permeable product consists of hollow microspheres of -Al₂O₃.

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. , . , –Al₂O₃.

     

Pressure distribution on the surface of a spherical segment entering a compressible fluid

The pressure on the progressively expanding wetted surface of a spherical segment entering a compressible fluid has been experimentally determined.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 9–14, March–April, 1986     

Statistical analysis of the results of humidity-temperature tests of glass reinforced plastics (GRP)

The effect of moisture and temperature factors on the strength of glass-reinforced plastics (GRP) is examined. In view of the considerable dispersion of the experimental data, a statistical method is used for analyzing the test results. The tensile strength distribution law for KAST-V glass laminate under various humidity and temperature conditions is analyzed.Mekhanika Polimerov, Vol. 1, No. 5, pp. 135–141, 1965     

Tantalum isocyanide complexes: TaI(CNDipp)6 (Dipp is 2,6‐diisopropylphenyl) and ionic [Ta(CNDipp)7][Ta(CNDipp)6], a formal disproportionation product of the 17‐electron Ta0 metalloradical Ta(CNDipp)6

Treatment of tetraethylammonium hexacarbonyltantalate, [Et₄N][Ta(CO)₆], with 1.1 equivalents of molecular iodine (I₂) in tetrahydrofuran (THF) at 200 K, followed by the addition of 6.0 equivalents of 2,6‐diisopropylphenyl isocyanide (CNDipp) and slow warming to 293 K over a 24 h period gave the tantalum(I) iodide derivative hexakis(2,6‐diisopropylphenyl isocyanide‐κC)iodidotantalum(I), [TaI(C₁₃H₁₇N)₆] or TaI(CNDipp)₆, 1 . Recrystallization of this substance from pentane provided deep‐red nearly black parallelepipeds of the product, which was characterized by single‐crystal X‐ray diffraction. Addition of 1 in THF at 200 K to a suspension of an excess (5.8 equivalents) of caesium graphite (CsC₈), followed by warming, filtration, and solvent removal, afforded a dark‐green oily solid of unknown composition, from which several red–brown rhombohedral plates of the ditantalum salt heptakis(2,6‐diisopropylphenyl isocyanide‐κC)tantalum hexakis(2,6‐diisopropylphenyl isocyanide‐κC)tantalate, [Ta(C₁₃H₁₇N)₇][Ta(C₁₃H₁₇N)₆] or [Ta(CNDipp)₇][Ta(CNDipp)₆], 2 , were harvested. Salt 2 is a unique substance, as it is the only known example of a salt containing a homoleptic cation, [ML_x]⁺, and a homoleptic anion, [ML_y]^?, with the same transition metal and π‐acceptor ligand L. In solution, 2 undergoes full comproportionation to afford the recently reported 17‐electron paramagnetic zerovalent tantalum complex Ta(CNDipp)₆, the only known isolable TaL₆ complex of Ta⁰.     

Hydrothermal Synthesis of Porous Al2O3/Al Metal Ceramics: I. Oxidation of Aluminum Powder and Structure Formation of Porous Al(OH)3/Al Composite

The properties of ASD-1 aluminum powder and its oxidation with water at 100°C were studied. It was found that the microstructure of a surface oxide film and the conditions of oxidation significantly affected the dynamics of changes in the pH of the solution and in the degree of aluminum conversion into the hydroxide. Experimental data on the oxidation in combination with electron-microscopic measurements and the determination of adsorption and texture characteristics resulted in the conclusion that colloid-chemical processes, which include the dissolution of aluminum and the formation and precipitation of the hydroxo complexes of aluminum, are fundamental for the synthesis of porous metal ceramics.     

Hydrothermal Synthesis of Porous Al2O3/Al Metal Ceramics: IV. Synthesis of Composite Porous Ceramics in the Presence of Microporous and Mesoporous Adsorbents

The formation of the structure and properties of mesoporous composite ceramics based on an ASD-1 aluminum powder and commercial adsorbent powders (zeolites and active alumina) was studied. It was found that the mechanism of the formation of contacts between the particles of commercial adsorbents and aluminum is analogous to the mechanism of synthesis of an Al(OH)₃/Al composite. The dissolution of aluminum and the precipitation of the hydroxo complexes of aluminum from solution to the region of interparticle contacts are responsible for this mechanism. The resulting composite ceramics exhibited a polydisperse pore structure and high values of mechanical strength, gas permeability, and thermal conductivity; it can be used as a block adsorbent and catalyst support.     

Experimental determination of the pressure on a disk entering a compressible fluid at an angle to the free surface

The results of experiments to determine the pressure on the surface of a disk entering a compressible fluid at an angle to the free surface are presented.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 21–25, March–April, 1988.