Activated aluminum for hydrogen generation from water

Al-based alloys and mechanochemically activated aluminum powders were prepared in this study, and the regularities of their hydrolysis reaction with water were studied. Aluminum alloys were prepared by melting aluminum with additions of Ga–In–Sn eutectic (5 wt.%), bismuth (3 wt.%), antimony (3 wt.%), or zinc (3 wt.%). The temperature-dependent kinetics of their hydrolysis in a temperature range 25–70 °C was studied by using a volumetric technique. The most efficient activation of the hydrolysis process was achieved for the Al–Ga– In–Sn-Zn alloy, particularly at low temperatures (5 and 25° C). The addition of bismuth to the Al–Ga–In–Sn alloy significantly decreases the hydrolysis rate, whereas the addition of antimony has only a weak effect on the process, despite the fact that the standard electrode potentials of bismuth and antimony have rather close values. Commercially available aluminum PA-4 and ASD-1 powders were mechanochemically activated by Ga–In–Sn or Ga–In–Sn–Zn eutectic alloys (5 wt.%) and graphite (1–3 wt.%) in a mixer type ball mill. Subsequently, they were pressed (P = 4 MPa) into the pellets, which were used to generate hydrogen from water via the hydrolysis process. X-ray diffraction study of the milled PA-4 powder revealed the presence of four phases, including aluminum, graphite, and two In–Sn intermetallic compounds (In3Sn and In1–xSnx, were x ≈ 0.04). The quantitative analysis by EDX showed a uniform distribution of the activating additives over the pellet surface, while the graphite was partly aggregated. Studies on the hydrolysis kinetics when utilizing Al-based pellets demonstrated that the process readily proceeds at temperatures ≥ 5° C. At the same time, the efficiency of hydrogen generation depends on the amount of the added graphite, particle size of aluminum powders, duration and medium of their mechanochemical treatment, and the hydrolysis temperature.

Effect of Cu(NO3)2 and Cu(CH3COO)2 Activating Additives on Combustion Characteristics of Anthracite and Its Semi-Coke

The process of anthracite and its semi-coke combustion in the presence of 5 wt.% (in terms of dry salt) additives of copper salts Cu(NO3)2 and Cu(CH3COO)2 was studied. The activating additives were introduced by an incipient wetness procedure. The ignition and combustion parameters for coal samples were examined in the combustion chamber at the heating medium temperatures (Tg) of 600–800 °C. The composition of the gaseous combustion products was controlled using an on-line gas analyzer. The fuel modification with copper salts was found to reduce the ignition delay time on average, along with a drop in the minimum ignition temperature Tmin by 138–277 °C. With an increase in Tg temperature, a significant reduction in the ignition delay time for the anthracite and semi-coke samples (by a factor of 6.7) was observed. The maximum difference in the ignition delay time between the original and modified samples of anthracite (ΔTi = 5.5 s) and semi-coke (ΔTi = 5.4 s) was recorded at a Tg temperature of 600 °C in the case of Cu(CH3COO)2. The emergence of micro-explosions was detected at an early stage of combustion via high-speed video imaging for samples modified by copper acetate. According to the on-line gas analysis data, the addition of copper salts permits one to reduce the volume of CO formed by 40% on average, providing complete oxidation of the fuel to CO2. It was shown that the introduction of additives promoted the reduction in the NOx emissions during the combustion of the anthracite and semi-coke samples.

On Increasing Powder Carbon Steels Properties Using Activating Additives

In this paper, the possibility of increasing powder carbon steels properties by activation of carbon diffusion into the iron base during sintering process due to the introduction of the thermally split graphite (TSG), macromolecular compounds (MC) and sodium bicarbonate was investigated. It was found that the introduction of these additives allows obtaining homogeneous structures at a sintering temperature of 100–200 °C lower than that traditionally used for sintering of powder carbon steels. Such structures provide increased mechanical properties of powder carbon steels. The addition of sodium bicarbonate increases the diffusion rate of carbon into iron at a temperature of 950 C by 1.8 times, at 1000 °C by 1.5 times, and at 1100 °C by 1.2 times.

WASTEWATER TREATMENT FROM HEAVY METAL IONS

The article considers the problem of wastewater treatment of industrial enterprises containing heavy metal ions. Because of insufficient treatment of wastewater from heavy metal ions, they enter ecological systems, accumulate in them and cause toxic effects on phyto and zoocenosis, even in small concentrations, which in turn leads to imbalance of ecosystems and their degradation. Therefore, the treatment of industrial effluents is becoming increasingly important over time. The application of existing methods and sorbents for purification of industrial effluents from heavy metal ions is considered and analyzed.However, existing combined wastewater treatment methods and sorbents have little effectiveness against heavy metals. The paper proposes the use of clay- based sorbents. The purpose of research is to substantiate the feasibility of using sorbents based on clays of deposits in Ukraine for wastewater treatment of industrial enterprises from heavy metal ions. Clays of domestic deposits are not scarce, inexpensive in comparison with existing sorbents. Samples of sorbents based on clay were studied, their composition was developed and analyzed.A method for obtaining clay-based sorbents has been developed. Materials such as peat, wood ash and dolomite were used as activating additives. The composition and structure of the developed sorbents, as well as their sorption capacity and ability to heavy metals have been studied. These sorbents have been shown to be an effective material for cleaning industrial effluents from heavy metal ions and can be recommended for use.

Employment of electric torch discharge and a steam-gas generator in surface schooping of materials

Subject and Purpose. The present paper is concerned with the method of surface schooping of materials using high-frequency torch discharge (HFTD) and glycerol vapor as a base for dissolving activating additives to the working gas. To approach the problem, a steam generator is employed in an effort to improve the HFTD catalytic performance in the activation of surfaces and deposition of coatings on them. The purpose is to develop a design technique of a steam generator intended for making a proper gas environment in the HFTD burning area. The discussed design techniques seek to enhance efficiency of the self-contained steam generator with allowance for its small size compared to the wavelength. Methods and Methodology. The analysis of the glycerol vapor behavior in the HFTD plasma depends on the knowledge of glycerol molecule ionization potential in the electron impact case. To find out about the measure to which the glycerol vapor affects the HFTD current, a known calcium ionization potential is used as a defined point. The heating elements as part of the steam generator are designed in terms of thermal design methodology adopted in the electroheating machine making. The calculation formulas of the running time ratios of the steam generator with various heating elements and energy efficiencies have been obtained in terms of galvanic cell theory. Results. It has been shown that glycerol vapor itself cannot affect the HFTD current. For the HFTD excitation, the microwave region has been chosen. In cooperation with activating additives to the discharge plasma, this factor also adds to the HFTD current increase. Hence, the HFTD catalytic performance depends not only on the HFTD energy and its excitation field frequency but on the glycerol-dissolved additives as well. A special design has been developed for the heating element as part of a small-size steam generator. Reference tables have been composed, enabling one to pick up a prpoper diameter and number of parallel connected wires in the spiral coil. Conclusion. A good use of glycerol vapor as a base for vaporous fluxes and activating additives to the HFTD working gas has been shown. The developed design technique concerning the heating element of the steam generator optimizes its heating circuit. Specifically, it enhances the steam generation and reduces the power consumption of the steam generator running on the galvanic cell. Second, it makes it possible to use stainless-steel spiral heating coils in regime of automatic temperature control.

Spark plasma sintering of Al2O3-ceramics ingots for small-sized end mills

The regularities of the influence of sintering temperature, pressure and duration of isothermal holding during spark plasma sintering on the structure of Al2O3ceramics not containing activating additives are determined. The revealed interrelations made it possible to determine the direction of the search for the optimal parameters of the sintering regime and formulate the technological recommendations for the sintering of ingots for smallsized end mills.Ill. 4. Ref. 26.

On the question of the applicability of G.V. Samsonov’s activated sintering concept in studying the processes of powder material deformation

Some Yu.G. Dorofeev’s memoirs about joint work and meetings with outstanding materials science expert G.V. Samsonov are given. Meetings in Yugoslavia were of particular importance where G.V. Samsonov and M.M. Ristićtogether with other worldfamous scientists created the International Institute for the Science of Sintering. In the last years of his life, G.V. Samsonov proposed the concept of sintering activation by additives that act as electron acceptors and additionally contribute to the ionic bond in the matrix material. The paper considers the possibility of using this concept in the development of activating additives that reduce the activation energy of the plastic deformation of iron-based powder materials. Sintering activation when forming stable electronic configurations can be accomplished by: 1) accelerating the grain-boundary heterodiffusion of the matrix material in the presence of phase segregations containing an activating microadditive (W–Ni system); 2) intensifying shrinkage durng the plastic flow of matrix material particles facilitated by diffusion porosity formed in the additive particles as a result of predominant additive atom diffusion into base metal particles (Fe–Ni, Fe–Co, Fe–Mn systems); 3) increasing the self-diffusion coefficient of base metal atoms due to the expanded area of a less close-packed crystal lattice (αphase) upon activating additive dissolution (Fe–Mo system). The article reviews the information available on the prospects for using manganese and chromium as compaction activating additives. The compaction activation energy of iron-based powder materials can be reduced by introducing manganese additives. At the same time, the use of diffusion saturation technology is promising. The question of using chromium as an activator does not have an unambiguous answer and suggests the need for further study.