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The interaction between dacitic tuff and calcium hydroxide under hydrothermal conditions has been investigated. At a ratio of CaO/SiO2 = 0.3–1.5 : 1 and at a ratio between the liquid phase and the solid phase amounting to 10 : 1, after 2 h at 220°C, calcium hydroxide is completely bound. As a result of the destruction of potassium feldspar in tuff, potassium can be transformed into a plant-digestible form.

The paper discusses the prospects of using metal-air electrochemical current sources, in particular the advantages of using magnesium as an anode. The methods for increasing the efficiency of the anode, electrolyte and cathode are analyzed. Moreover, the paper presents the comparative electrochemical characteristics of various metals used as an anode, their effectiveness, advantages, and availability. At the same time, this research considers a number of problems that are specific to metal-air current sources and ways to overcome them. We discuss the methods for reducing the cost of magnesium production and utilization of the by-product of the reaction – magnesium hydroxide based on a new technology (ECOATOM, LLC; Republic of Armenia).

The opportunities of use of metallic magnesium as a generator of hydrogen gas, as well as thermal and electric energy is presented in the paper. Various schemes of magnesium application are discussed and power characteristics of corresponding devices are presented. Economic estimation of hydrogen price obtained by different methods is made, including the use of magnesium as a source of hydrogen for transportation in comparison with gasoline. Details and prospects of our new inexpensive technology of magnesium production from magnesium hydroxide and magnesium bearing rocks (which are available worldwide and in Armenia) are analyzed. It is estimated the threshold cost of Mg production at which application of this metal in power engineering is economically justified., {"references":["T. Williams, \"Reaction and Thermal Modeling of a Packed Bed Reactor for Hydrogen Storage\", in Proc. of the COMSOL Conference, Boston, 2007.","A. Du, S.C. Smith, G.Q. 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Yang, Y. Liu, J. Ruan, S. Yang, X. Liu, \"Hydrogen generation by the hydrolysis of magnesium–aluminum–iron material in aqueous solutions\", International Journal of Hydrogen Energy, vol. 39, no. 21, pp. 10843–10852,July 2014.\n[10]\tD. Cao, L. Wu, Y. Sun, G. Wang, Y. Lu,\"Electrochemical behavior of Mg−Li, Mg−Li−Al and Mg−Li−Al−Ce in sodium chloride solution\", Journal of Power Sources, vol. 177, no. 2,pp. 624−630, Mar. 2008.\n[11]\tA.R. Suresh Kannan, S. Muralidharan, K.B. Sarangapani, V. Balaramachandran, V. Kapali, \"Corrosion and anodic behaviour of zinc and its ternary alloys in alkaline battery electrolytes\", Journal of Power Sources, vol. 57, no. 1, pp. 93−98, Sept.-Dec. 1995.\n[12]\tF. Pacheco, \"Hydrogen Generator\", US Patent 6834623, Dec. 2004.\n[13]\tY. Yan, Ionic Liquid Electrolytes in Mg-Air Batteries, Dissertation, Institute for Frontier Materials Deakin University, Jan. 2016.\n[14]\tT. Zhang, Z. Tao and J. 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By choosing appropriate stabilizing additions and optimizing the thermal treatment, aluminum titanate with a low thermal expansion coefficient (TEC) (minus 3.38.10 - 6 K - 1 in the interval of 20 - 200 °C) and hysteresis (0.07 % at 400 °C) was obtained. The material was used as an additive for decreasing the TEC of alumina. Destructive thermal stresses were overcome by optimizing the milling and homogenization technique. The sintering rates, phase content and microstructure are described.

An influence of β-eucryptite glassceramics on the sintering ability, sintering mechanisms, and structure of alumna ceramics has been researched by methods of DTA, TG, DTG, XRD, dilatometry, optical and electronic microscopy. The thermal incompatibility between Al 2 O 3 and β-eucryptite glassceramics that results from the difference between their thermal coefficients of expansion (TEC) has been overcome by use of superfine powders and thorough blending of the base mixture. A phase composition, microstructure, TEC, mechanical and electrical properties, and thermal-shock resistance of alumina ceramics containing β-eucryptite glassceramics have been determined. A possibility of replacing β-eucryptite glassceramics by the equivalent amount of Li 2 O.2SiO 2 containing glass or a mixture of Li 2 CO 3 . SiO 2 powders has been demonstrated.