Optical properties of powder and ceramics of aluminium oxynitride obtained by self-propagating high-temperature synthesis

The synthesis method of aluminium oxynitride (AlON) powders by nitriding of Al/Al2O3 mixture under highpressure nitrogen is proposed. The novelty of this method consists in adding KClO4 or Mg(ClO4)2 and extra Al into the starting mixture (Al+Al2O3) to cause the exothermal aluminium oxidation reaction, which therefore initiates the aluminium nitriding reaction. The microstructure and phase composition of the AlON powders obtained by self-propagating high-temperature synthesis are demonstrated by means of SEM and XRD analysis. Diffuse reflection spectra of AlON powders have been measured and the values of band-gap energy have been calculated. Optical transmission and reflection characteristics of the AlON ceramic samples sintered from AlON powders at 1930°C have been studied. The influence of the technological parameters of ceramics production on their transparency is revealed – the most transparent sample is obtained from the powders synthesized with the Mg(ClO4)2 additive and sintered for 6 h.

Hopping Conductivity and Dielectric Relaxations in Ag/PAN Nanocomposites

The dependence of the conductivity and electric modulus of silver/polyacrylonitrile nanocomposites on the frequency of an alternating electric field has been studied at different temperatures and starting mixture AgNO3 contents. The frequency dependences on the conductivity of the nanocomposites in the range of 103–106 Hz are in good agreement with the power law f0.8. The observed relaxation maxima in the relation of the imaginary part of the electric modulus on the frequency can be explained by interfacial polarization. It was shown that the frequency dispersions of conductivity and electric modulus were well described by the Dyre and Cole-Davidson models, respectively. Using these models, we have estimated the relaxation times and the activation energies of these structures. A mechanism of charge transport responsible for the conductivity of nanocomposites is proposed. An assumption is made regarding the presence of Ag42+ and Ag82+ silver clusters in the polymer.

Worth from Waste: Utilizing a Graphite-Rich Fraction from Spent Lithium-Ion Batteries as Alternative Reductant in Nickel Slag Cleaning

One possible way of recovering metals from spent lithium-ion batteries is to integrate the recycling with already existing metallurgical processes. This study continues our effort on integrating froth flotation and nickel-slag cleaning process for metal recovery from spent batteries (SBs), using anodic graphite as the main reductant. The SBs used in this study was a froth fraction from flotation of industrially prepared black mass. The effect of different ratios of Ni-slag to SBs on the time-dependent phase formation and metal behavior was investigated. The possible influence of graphite and sulfur contents in the system on the metal alloy/matte formation was described. The trace element (Co, Cu, Ni, and Mn) concentrations in the slag were analyzed using the laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) technique. The distribution coefficients of cobalt and nickel between the metallic or sulfidic phase (metal alloy/matte) and the coexisting slag increased with the increasing amount of SBs in the starting mixture. However, with the increasing concentrations of graphite in the starting mixture (from 0.99 wt.% to 3.97 wt.%), the Fe concentration in both metal alloy and matte also increased (from 29 wt.% to 68 wt.% and from 7 wt.% to 49 wt.%, respectively), which may be challenging if further hydrometallurgical treatment is expected. Therefore, the composition of metal alloy/matte must be adjusted depending on the further steps for metal recovery.

Solvent-Free Synthesis of SAPO-34 Zeolite with Tunable SiO2/Al2O3 Ratios for Efficient Catalytic Cracking of 1-Butene

Solvent-free synthesis methodology is a promising technique for the green and sustainable preparation of zeolites materials. In this work, a solvent-free route was developed to synthesize SAPO-34 zeolite. The characterization results indicated that the crystal size, texture properties, acidity and Si coordination environment of the resulting SAPO-34 were tuned by adjusting the SiO2/Al2O3 molar ratio in the starting mixture. Moreover, the acidity of SAPO-34 zeolite was found to depend on the Si coordination environment, which was consistent with that of SAPO-34 zeolite synthesized by the hydrothermal method. At an SiO2/Al2O3 ratio of 0.6, the SP-0.6 sample exhibited the highest conversion of 1-butene (82.8%) and a satisfactory yield of light olefins (51.6%) in the catalytic cracking of 1-butene, which was attributed to the synergistic effect of the large SBET (425 m2/g) and the abundant acid sites (1.82 mmol/g). This work provides a new opportunity for the design of efficient zeolite catalysts for industrially important reactions.

Ni-in-garnet geothermometry in mantle rocks: a high pressure experimental recalibration between 1100 and 1325 °C

The temperature-dependent exchange of Ni and Mg between garnet and olivine in mantle peridotite is an important geothermometer for determining temperature variations in the upper mantle and the diamond potential of kimberlites. Existing calibrations of the Ni-in-garnet geothermometer show considerable differences in estimated temperature above and below 1100 °C hindering its confident application. In this study, we present the results from new synthesis experiments conducted on a piston cylinder apparatus at 2.25–4.5 GPa and 1100–1325 °C. Our experimental approach was to equilibrate a Ni-free Cr-pyrope-rich garnet starting mixture made from sintered oxides with natural olivine capsules (Niolv ≅ 3000 ppm) to produce an experimental charge comprised entirely of peridotitic pyrope garnet with trace abundances of Ni (10–100 s of ppm). Experimental runs products were analysed by wave-length dispersive electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We use the partition coefficient for the distribution of Ni between our garnet experimental charge and the olivine capsule $$\left( {{\text{lnD}}_{{{\text{grt}}/{\text{olv}}}}^{{{\text{Ni}}}} ; \frac{{{\text{Ni}}_{{{\text{grt}}}} }}{{{\text{Ni}}_{{{\text{olv}}}} }}} \right)$$ lnD grt / olv Ni ; Ni grt Ni olv , the Ca mole fraction in garnet ($${\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Ca}};$$ X grt Ca ; Ca/(Ca + Fe + Mg)), and the Cr mole fraction in garnet ($${\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Cr}};$$ X grt Cr ; Cr/(Cr + Al)) to develop a new formulation of the Ni-in-garnet geothermometer that performs more reliably on experimental and natural datasets than existing calibrations. Our updated Ni-in-garnet geothermometer is defined here as:$$T \left(^\circ{\rm C} \right)=\frac{-8254.568}{\left(\left( {\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Ca}} \times 3.023 \right)+\left({\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Cr}} \times 2.307 \right)+\left({\mathrm{lnD}}_{\frac{\mathrm{grt}}{\mathrm{olv}}}^{\mathrm{Ni}} - 2.639 \right)\right)}-273\pm 55$$ T ∘ C = - 8254.568 X grt Ca × 3.023 + X grt Cr × 2.307 + lnD grt olv Ni - 2.639 - 273 ± 55 where $${\mathrm{D}}_{\mathrm{grt}/\mathrm{olv}}^{\mathrm{Ni}}= \frac{{\mathrm{Ni}}_{\mathrm{grt}}}{{\mathrm{Ni}}_{\mathrm{olv}}},$$ D grt / olv Ni = Ni grt Ni olv , Ni is in ppm, $${\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Ca}}$$ X grt Ca = Ca/(Ca + Fe + Mg) in garnet, and $${\mathrm{X}}_{\mathrm{grt}}^{\mathrm{Cr}}$$ X grt Cr = Cr/(Cr + Al) in garnet. Our updated Ni-in-garnet geothermometer can be applied to garnet peridotite xenoliths or monomineralic garnet xenocrysts derived from disaggregation of a peridotite source. Our calibration can be used as a single grain geothermometer by assuming an average mantle olivine Ni concentration of 3000 ppm. To maximise the reliability of temperature estimates made from our Ni-in-garnet geothermometer, we provide users with a data quality protocol method which can be applied to all garnet EPMA and LA-ICP-MS analyses prior to Ni-in-garnet geothermometry. The temperature uncertainty of our updated calibration has been rigorously propagated by incorporating all analytical and experimental uncertainties. We have found that our Ni-in-garnet temperature estimates have a maximum associated uncertainty of ± 55 °C. The improved performance of our updated calibration is demonstrated through its application to previously published experimental datasets and on natural, well-characterised garnet peridotite xenoliths from a variety of published datasets, including the diamondiferous Diavik and Ekati kimberlite pipes from the Lac de Gras kimberlite field, Canada. Our new calibration better aligns temperature estimates using the Ni-in-garnet geothermometer with those estimated by the widely used (Nimis and Taylor, Contrib Mineral Petrol 139:541–554, 2000) enstatite-in-clinopyroxene geothermometer, and confirms an improvement in performance of the new calibration relative to existing versions of the Ni-in-garnet geothermometer.

STUDY OF GRANULATION PROCESS OF ILMENITE CONCENTRATE BY PELLETING METHOD

The use of highly dispersed ilmenite ore in the titanium concentrate enrichment technology is accompanied by high dustiness at the stage of titanium charge preparation, which inevitably leads to technological losses and adversely affects the working conditions of the staff. In connection with this, the aim of the present work was to study the process of granulating ilmenite concentrate from the Malyshevsky deposit by pelletization. The size and morphology of ilmenite concentrate particles were determined using a high-resolution electron scanning microscope and a laser diffraction particle size analyzer. The granulation process was carried out in a drum granulator thermostated by assessing the effect of temperature, rotation speed granulator, process duration and a binder flow rate on particle size distribution and static strength formed granules of the title product. During the investigations it was established that the maximum yield of granules fraction of 1.0 - 5.0 mm was obtained using an aqueous solution of molasses molasses volume ratio: water = 5:1. The use as undiluted molasses binder leads to a strong increase in ductility formed mass and negatively affects the possibility of producing a granular product. It was shown that with increasing concentration of binder in the composition of the starting mixture the average yield and static strength of granules fraction of 1.0 - 5.0 mm increases, due to the uniform distribution of the solution between the ilmenite concentrate particles. At the same time when the amount of binder in the composition of the starting raw materials over 9.5% the formation of relatively large lumps is observed, which size is more than 5.0 mm. It has been experimentally proved that with increasing duration pelletization yield pellets of ilmenite concentrate fraction of 1.0 - 5.0 mm increases, passing through a maximum at 300 s.

SYNTHESIS OF Cu1.6Bi4.6S8 COMPOUND FOR THERMOELECTRIC APPLICATION

<p class="AMSmaintext">In this work, Cu_1.6Bi_4.6S₈ thermoelectric compound was synthesized using high energy milling and heat treatment. The starting mixture include Cu, Bi and S elemental powders at the stoichiometry ratio of the formula Cu_1.6Bi_4.6S₈ were ball milled in a planetary ball mill and heat treated in an electric furnace. The results shown that after 10 hours of milling, a compound identified as Cu_3.21Bi_4.79S₉ was formed. The 16h milled powder was heat-treated at 350, 400 and 450ºC for 1 hours at a heating rate of 8 ºC/minute, XRD of the annealed powder reveals that the Cu_3.21Bi_4.79S₉ obtained fully transformed into Cu_1.6Bi_4.6S₈ after being heat treated at 400ºC. Meanwhile, Bi₂S₃ was found in the powder being annealed at 350ºC. The 5h milled powder was also annealed at 400ºC for 1 hours at a heating rate of 2 and 8 ºC/minute, XRD analysis show that Cu_1.6Bi_4.6S₈ was also formed in the heat-treated powder with the heating rate of 2 ºC/min.</p>

The Development of Technology of Basalt Nanocomposite Coatings Detonation-Gas Spaying on the Disk («Target») Basis of Thin Layer Magnetron Spaying Equipment

The chemical composition, structure and microhardness of detonation coatings based on mechanically activated mixture of basalt powder and TiAl have been studied. It has been shown that the application of mechanomixture with detonation method results in the formation of composite coating similar to the composition of starting mixture. It has high microhardness and temperature resistance that will increase the wear resistance of the parts coated with basalt at elevated temperatures.

Features of the Use of Low-Toxic Resins in the Technology of Wood Particle Boards

Source of release of harmful gas of wood particle board (WPB) – formaldehyde is not only free formaldehyde presenting in the formaldehyde resin, but formaldehyde, which is formed from hydroxymethylene groups in a weakly acidic environment during curing the resin during hot pressing of boards. In this, dimethylaniline connections are formed. They are unstable and go into methylene linkages (bridges) with the release of formaldehyde. Currently, with the goal of reducing the discharge formaldehyde from the boards of, low-molal urea-formaldehyde resin is used, mole ratio in which (carbamide (C) : formaldehyde (F) in resins preparing is at the level of (1:1.2 – 1:1.35). Thus we obtain resin with low content of free formaldehyde (0.10-0.15 % by weight of liquid resin). However, it is known that to obtain resins with good adhesive ability, and thus obtaining boards with good physical and mechanical and performance properties, excess of formaldehyde is necessary in its reaction with carbamide. With a relatively small excess of formaldehyde in the starting mixture of urea-formaldehyde we get resins with low reactivity. With increasing quantities of formaldehyde, it is growing vigorously. The highest reactivity corresponds to the mole ratio of carbamide and formaldehyde (C:F) 1:2. When the mole ratio of C:F=1:1 in the synthesis process substances are formed which have no adhesion to the wood. Therefore, the use of low molal resin in wood particleboard technology has not only its positive side (reduced evolution of formaldehyde from plates) but also negative ones (deteriorating physical and mechanical properties of the plates). In this regard for obtaining low-toxic wood particleboard, except for use of low-toxic resins in the technology, it is necessary to apply effective acceptor of formaldehyde. Moreover, it is advisable to use acceptor complex action, which not only linked formaldehyde in the boards, but also improves physical and mechanical and special properties of boards (bio-, water-, atmospheric constancy, etc.).

Composite Polymer-Clay Hydrogels Based on Bentonite Clay and Acrylates: Synthesis, Characterization and Swelling Capacity

Clay minerals, especially montmorillonite, as well as bentonite minerals with a high content of montmorillonite, have the highest ability to adsorb various organic compounds. In the East Kazakhstan region, the Manyrak deposit has huge deposits of “pink” bentonite clay (BC) with 70% of montmorillonite, extensively studied back in the 70-80-s. Now it is successfully useful in the organo-polymer composition as a mineral filler of polymer composite materials (PCM) and finds the application as domestic sorbents for the group extraction of non-ferrous ions in the purification of industrial sewage and drinking water. This article presents the results of research of creating polymer-clay composite materials based on domestic bentonite clay with improved sorption characteristics. The polymeric matrix of the composites consists of acrylates ‒ polyacrylic and polymethacrylic acids (PAA and PMAA). BC-PAA and BC-PMAA gels were obtained by radical polymerization “in situ” using the intercalation method (and wi thout it). Preliminary intercalation forms more homogeneous and interconnected composite gels. An increase in the content of the clay component and the cross-linking agent in the starting mixture results in a higher cross-linking rate and compaction of the composite gels. The behavior of the swelling of gels under the influence of temperature, pH, ionic strength indicates their polyelectrolyte character with dominant hydrogen bonds and partial hydrophobic interactions (the latter is improved in the case of BC-PMAA). The preparation of composite gels based on local BC and PAA and PMAA expands the range of composite materials and can be used as sorbents for wastewater treatment.