Intergranular Space Research Articles

Metabolomics and microscopic profiling of flaxseed meal- incorporated Peda

Functional dairy foods are in high demand due to their convenience, enhanced nutrition, intriguing flavors, and natural ingredients. The valorization of flaxseed by-products can potentially boost the functionality of these foods. This work involves the optimization of flaxseed meal powder (2%, 2.5%, 3%) during Peda preparation based on sensory and textural attributes. The optimized Peda (2%) exhibited significantly reduction in moisture (39.6%) and water activity (18.9%), while significantly increasing crude fiber (1.88%), protein (26.4%), fat (8%) and DPPH inhibition (274.5%) as compared to control Peda. Scanning electron microscopy of the optimized Peda revealed the surface displayed a dense, uneven texture, heavily coated with fat, and intergranular spaces filled with milk serum. Twenty-three primary compounds were recognized in high-resolution mass spectrometry (HR-MS), including 6 organic acids, 6 amino acids, 3 fatty acids, 3 other metabolite derivatives, 2 lipids, 2 bioactive components, and 1 sugar. Besides gas chromatography mass spectrometry (GC–MS) found six separate types of fatty acids. These compounds have been proven to possess various bioactivities, such as promoting brain activity, antioxidant, anti-diabetic, anti-inflammatory, cardiovascular-protective effects, etc. Flaxseed meal, as a plant-based substitute for dairy ingredients, offers a sustainable and healthy alternative, making flaxseed-incorporated Peda a functional food.

Ultrathin Carbon Textures Produced on Machined Surfaces in an Integrated Finishing Process Using Microabrasive Films.

This study presents research into the unique method of depositing carbon layers onto processed surfaces, during finishing with abrasive films, on a global basis. The authors of this article are holders of the patent for this method. What makes this technology outstanding is that it integrates processes, whereby micro-finishing and the deposition of a carbon layer onto freshly exposed surface fragments is achieved simultaneously, in a single process. Among the main advantages accruable from this process is the reduction of surface irregularities, while the deposition of a carbon layer is achieved simultaneously. Ultrathin graphite layers can be widely used in conditions where other methods of reducing the coefficient of friction are not possible, such as in regard to micromechanisms. This article illustrates the application of carbon coating, end on, on a surface processed with abrasive film, containing intergranular spaces, saturated with graphite. Thin carbon layers were obtained on two substrates that did not contain carbon in their initial composition: soda-lime glass and a tin-bronze alloy. It was performed through microscopic examinations of the produced surface, roughness analyses of these surfaces, and analysis of the chemical compositions determined by two methods, namely EDS and GDOES, proving the existence of the coatings. The aim of this paper is to prove the possibility and efficiency of using graphite-impregnated lapping films in the deposition process of carbon films, with improved surface smoothness, durability, and wear resistance. The produced coatings will be tested in regard to their operational properties in further research. The authors underline the potential of this method to revolutionize surface treatment processes, due to the significant advantages it offers across various industries.

Boosting tough metal Zn anode by MOF layer for high-performance zinc-ion batteries

Metal-organic frameworks (MOFs) have been used to stabilize the metal zinc anode, yet the developed coating materials ignore the influence of intergranular space on deteriorating Zn electrode. Herein, we propose the channel sizes of MOFs as the key control factor to balance the zinc ion flux and Zn2+ desolvation behavior within the channels and between the intergranular spaces. Among three coating layers made by MOFs, the MOF-5W layer with confined spaces and channels is capable to promote the spontaneous desolvation process. The activated surface sites on MOF-5W endow the intergranular channels with accelerated ion transportation and spontaneous Zn2+ desolvation. Two kinds of migration paths are well-matched, as the MOF-5W@Zn anode shows Zn stripping/plating over 5000 cycles at 40 mA cm‒2, as well as cycling stability of 1050 h with high areal capacity of 10 mAh cm‒2. The findings enlighten the innovative research for tough Zn anode.

Unraveling the dual cracking mechanism of 316L/CuSn10 heterostructures fabricated by laser powder bed fusion

A comprehensive understanding of cracking mechanisms and the prevention of interfacial microcrack formation are imperative for additive manufacturing of high-performance multi-material heterostructures. This study systematically investigated 316L/CuSn10 heterostructures and identified solidification cracking and solid-state cracking as the predominant mechanisms. Solidification cracking is closely linked to the copper content within the mixing zone, particularly evident at 10% copper content, which heightens sensitivity to solidification cracking due to the widening of intergranular spacing and the elongation of the liquid film channel. Solid-state cracks tend to initiate from pre-existing solidification cracks, propagate along high-angle grain boundaries (HAGBs), particularly within a specific misorientation angle range of 20°–50°, terminating eventually at low-angle grain boundaries (LAGBs). This is mainly controlled by the distribution of dislocations at crack tips, which are dispersed within the grains at LAGBs, and the resulting back stress contributes to crack termination. These findings contribute valuable insights into the cracking mechanisms in heterostructures and offer guidance for the fabrication of crack-free steel-copper components.

Calcareous bioconstructions formation during the last interglacial (MIS 5) in the central Mediterranean: A consortium of algal, metazoan, and microbial framebuilders (Capo Colonna - Crotone basin - South Italy)

The last interglacial (MIS 5) transgressive-regressive deposits of the Capo Colonna marine terrace provide a good fossil example of a Central Mediterranean infra/circa-littoral setting, characterized by both calcareous coralline algae-dominated low-relief bioherms and biostromes, equivalent respectively to the modern coralligenous and mäerl habitats. The skeletal primary framework of the bioherms, consists of laminar to massive encrusting coralline red algae acting as main bioconstructors, with minor bryozoans, encrusting foraminifera, and serpulids as secondary frame-builders. Whereas, the autochthonous mäerl tabular beds are mainly composed of free-branched coralline red algae rudstone. A variable amount of sandy bioclastic sediment is laterally interbedded with the bioconstructions and tends to be entrapped in their cavities and pockets. All sedimentary sub-facies of the bioconstructions and associated sediment are rich in autochthonous syn-sedimentary microbial-mediated micrite, forming aphanitic, peloidal, clotted peloidal, and filamentous fabrics. Microbial micrite can also trap and bind a variable amount of grains, or be a secondary component of the sandy sediment as micritic rims surrounding the clasts. All these early-lithified micrites show the typical nanostructure of the primary microbial-mediated carbonates, rather than a detrital mud particles accumulation, as they consist of nanospheres coalescing into subhedral microcrystals that replace both microbial cells (present with several morphological types) and extracellular substances. This in turn implies the original widespread presence of benthic lithifying microbial biofilms which colonized both the cavities of the skeletal framework of the bioconstructions, and the intergranular space of the associated sediment. These microbial communities, thanks to the metabolic processes of the microorganisms that induced the carbonate precipitation, significantly contributed to the early cementation of all the studied deposits.

Experimental research on the influence of acid on the chemical and pore structure evolution characteristics of Wenjiaba tectonic coal.

The chemical and pore structures of coal play a crucial role in determining the content of free gas in coal reservoirs. This study focuses on investigating the impact of acidification transformation on the micro-physical and chemical structure characteristics of coal samples collected from Wenjiaba No. 1 Mine in Guizhou. The research involves a semi-quantitative analysis of the chemical structure parameters and crystal structure of coal samples before and after acidification using Fourier Transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) experiments. Additionally, the evolution characteristics of the pore structure are characterized through high-pressure mercury injection (HP-MIP), low-temperature nitrogen adsorption (LT-N2A), and scanning electron microscopy (SEM). The experimental findings reveal that the acid solution modifies the structural features of coal samples, weakening certain vibrational structures and altering the chemical composition. Specifically, the asymmetric vibration structure of aliphatic CH2, the asymmetric vibration of aliphatic CH3, and the symmetric vibration of CH2 are affected. This leads to a decrease in the contents of -OH and -NH functional groups while increasing aromatic structures. The crystal structure of coal samples primarily dissolves transversely after acidification, affecting intergranular spacing and average height. Acid treatment corrodes mineral particles within coal sample cracks, augmenting porosity, average pore diameter, and the ratio of macro-pores to transitional pores. Moreover, acidification increases fracture width and texture, enhancing the connectivity of the fracture structure in coal samples. These findings provide theoretical insights for optimizing coalbed methane (CBM) extraction and gas control strategies.

Platinum-bearing Fe-Mn oceanic crust on basalts: mineralogy and model of formation

Fe-Mn oceanic crust on basalts of the guyot in the Mid-Pacific Seamount (Pacific Ocean, depth 2486 m, chemical composition (wt %): Mn 24.2, Fe 12.6, Ni 0.59, Co 0.72, Cu 0.13; (ppm) Pt 0.35, Pd 0.0052), was studied using 3D-technology of mineralogical research. In addition to dominaiting vernadite and goethite, the following minerals are identified in the hydroseparation (HS) concentrates of the crust: 1) rock forming and accessory minerals of basalts (clinopyroxene, plagioclase, potassium feldspar, biotite, ilmenite, titanomagnetite, Ti-chrome spinel, zircon, apatite); 2) sulfides that are identical to those from the basalt substrate (pyrite, chalcopyrite, bornite, chalcocite, tennantite, nickel pentlandite Ni4S3, sphalerite, galena, argentite/acantite, molybdenite); 3) native metals (iron, nickel, copper, titanium, tungsten); 4) iron silicides (gupeiite Fe3Si, xifengite Fe5Si3, and hapkeite Fe5Si3); 5) platinum group minerals - unnamed (Cu,Pt)4Si and rustenburgite (Pt,Pd)3(Sn,Sb). The complexes of ore minerals in basalts are identical to those of the Fe-Mn crusts. Basalt accessories are assumed to be primary phases and a source of metals for the formation of native minerals. “Microdroplets” of native iron Fe, (Fe,Ni), nickel Ni, (Ni,Cr), (Ni,Fe) and copper Cu (sizes 20–100 microns, degree of sphericity up to 100%) represent the products of their crystallization from metal melts in basalts, transported by deep fluid into Fe-Mn crusts on these rocks. The zoned microglobules of 20–70 microns sizes with iron or native nickel (core) + successive rims of wüstite-magnetite and Fe-Mn hydroxides were identified. They were apparently formed during the movement of these solid microparticles (from bottom to the top) along intergranular spaces and other permeability channels in basalts under conditions of increasing oxygen fugacity and falling temperature at various levels of deep fluid infiltration. The crystallization of native metals in the Fe-Mn crust that are characterized by low-temperature (10 °C) and oxidizing (fO2 MHG magnetite-hematite-goethite) conditions of mineral formation is impossible. The goethite replacement to different extent of many grains of relict Fe-minerals (sulfides and native metals) that are “foreign” to the Fe-Mn crust have been established. Fe-Mn crusts were formed as a result of the precipitation of colloidal particles Mn2+(Ba2+и Sr2+), to a lesser extent of the iron hydroxide Fe(ОН)3, as well as the concentration and transformation of micrograins of minerals of other metals, extracted by fluid from basaltic substrates. The comparison of the physico-chemical parameters of crystallization of basalts and native metals suggests another source of formation of native minerals in basalts, different from the postmagmatic basaltic fluid, i.e. deep-seated sharply reducing "hot" gas flows associated with superplumes. The mineralogical data determines a volcanogenic-fluid-oceanic model for the formation of Fe-Mn crusts on underwater oceanic elevations.

Pre-concentration of REE values from nepheline syenite rocks of western Odisha, India

ABSTRACT The rare-earth elements (REEs) have gained enormous economic and scientific attention due to their distinct properties and new applications. Nepheline syenite rock is an important primary source of rare earth minerals. The nepheline syenite rocks from the Rairakhol area, western Odisha, have been characterized for their rare earth mineralogical and textural characteristics. Preliminary beneficiation studies of these rocks were carried out to upgrade the REE values using falcon gravity separation and floatation technique. Hornblende, biotite, K-feldspar, albite, and nepheline are the major mineral constituents of the nepheline syenite where REE-bearing minerals occur as accessory minerals. The REE mineral phases present are zircon, sphene, apatite, allanite, britholite, and REE phosphate, with grain sizes ranging from 10 to 50 microns. Allanite and britholite occupy the intergranular spaces of major mineral phases and occur as thin lines or veins whereas sphene and zircon occur as inclusions within major mineral phases. The flotation study shows that the total REE content of the froth product could be enriched to 1696 ppm, which is three times more than the total REE content (563 ppm) of the feed sample.

Implications of the depositional and diagenetic attributes on the reservoir properties of the siliciclastic mangahewa formation, Taranaki Basin, New Zealand: Integrated petrographical and petrophysical studies

The siliciclastic Mangahewa reservoir in the Pohokura Gas Field presents a formidable challenge for gas exploration due to its diverse petrophysical properties. To address this challenge, our study employs a comprehensive approach integrating petrography and petrophysical analyses for core and well logging data. In the present study, we uncover an association of sandstone microfacies, in the key wells like Pohokura South-1, Pohokura-1, and Pohokura-2 wells, which change from fine to medium-grained subfeldsarenites to lithic feldsarenites microfacies. The petrographic investigation pinpoints the critical factors influencing the reservoir quality, including facies types, grain size, pore types, sedimentary structure, detrital clay content, and mineral composition. Both the primary intergranular and secondary dissolution pore spaces are responsible for the influential large intergranular pore volumes causing a superior reservoir quality. Mineral composition, influenced by the source and lithofacies, significantly impacts the reservoir properties. Diagenetic processes further control the reservoir quality, where the abundant silica cement, the illitic clays, and the rare pervasive carbonate cementation render the low reservoir quality. Compaction significantly reduces porosity during diagenesis. High-quality reservoir sandstones are characterized by coarse grain size, minimal detrital clay presence, predominantly quartz composition, limited carbonate and moderate silica cementation, low authigenic illite levels, and minor compaction impact. Based on the petrophysical data, the Mangahewa reservoir is composed of five RRTs (reservoir rock types) with the RRT1 samples having the best reservoir characteristics due to their fair porosity, very good permeability, and macro pore sizes. On the other side, the RRT5 samples are characterized by the lowest reservoir quality (poor porosity and permeability and micropore sizes) due to cementation and compaction. Our study provides valuable insights into the intricate petrophysical properties of the Mangahewa reservoir, enhancing the predictability of the reservoir behavior and optimizing hydrocarbon production in this challenging geological setting.

Structural characteristics and properties of heat-resistant nickel β-alloys produced via the centrifugal SHS-casting method

Employing centrifugal self-propagating high-temperature synthesis (SHS) metallurgy, complemented by advanced metallurgical processes such as vacuum induction melting (VIM) and vacuum arc remelting (VAR), yielded the alloy formulation denoted as base–2.5Mo–1.5Re–1.5Ta–0.2Ti. This study investigates the effects of various technological modes and additional metallurgical treatments on the alloy's impurity and non-metallic inclusion content, structural characteristics, mechanical behavior under compression, and its oxidation mechanisms and kinetics when exposed to temperatures of 1150 °C for 30 h. With increasing centrifugal acceleration, the proportion of non-metallic inclusions (number of points) drops from 5 to 1–2 points. The best combination mechanical properties, including σucs = 1640 ± 20 MPa, σys = 1518 ± 10 MPa, and residual deformation were observed in alloys processed under conditions of increased gravitational force (g = 50). Within a centrifugal force range of g = 20÷300, the composition of the synthesis products aligned with the theoretical expectations. The total content of impurities is 0.15 ± 0.02 %, with a decrease in gas impurities–oxygen and nitrogen levels reduced to 0.018 % and 0.0011 %, respectively. The structural analysis of the alloys revealed the presence of globular and streaked inclusions of a chromium-based solid solution embedded within the matrix. Inclusions with thickness of 2–8 μm are present in the intergranular space: (Cr)Ni,Mo,Co, (Cr)Mo,Re and (Cr)Re,Mo. The formation of the Ni(Al,Ti) phase at grain boundaries was identified, contributing to an enhancement in plastic resistance and overall strength of the alloy. Oxidation mechanisms varied across different processing modes, with the size of structural components significantly influencing oxidation kinetics. The weight gain observed in SHS samples was 70 ± 10 g/m2 with oxidation predominantly occurring along the NiAl interphase boundaries and penetrating into the depth of the sample. TEM facilitated the identification of phases enriched with Ti microadditions, reducing the levels of dissolved nitrogen and oxygen within the intermetallic phase to a combined weight percentage (ΣO,N) of 0.0223 wt.%.

Water-Containing Defects in Variously Deformed Milky-White Vein Quartz of the Larino Deposit (South Urals)

Abstract ––The methods of Infrared (IR) and Raman spectroscopy, as well as gas chromatography, were used to assess the distribution, content and composition of water-containing defects in variously deformed milky-white vein quartz of the Larino deposit. Weakly deformed quartz and quartz with intensive polygonization and recrystallization, in which water is present in molecular form, in fractures, channels, intergranular space, as well as in the composition of fluid inclusions, are analyzed. The content of water-containing defects, according to IR spectroscopy and gas chromatography, decreases in a series from weakly deformed primary granular coarse-grained quartz to blocked and recrystallized. The obtained results indicate the release of water during recrystallization, along the newly formed grain boundaries by diffusion and further homogenization to achieve an equilibrium state. Gas content also depends on the degree of deformation changes in samples and decreases from large coarse-grained differences to intensely deformed quartz with a high content of recrystallized grains.

Experimental Study on Liquid Metal Embrittlement of Al-Zn-Mg Aluminum Alloy (7075): From Macromechanical Property Experiment to Microscopic Characterization.

This study is a multiscale experimental investigation into the embrittlement of Al-Zn-Mg aluminum alloy (7075-T6) caused by liquid metal gallium. The results of the experiment demonstrate that the tensile strength of the 7075-T6 aluminum alloy significantly weakens with an increase in the embrittlement temperature and a prolonged embrittlement time, whereas it improves with an increase in the strain rate. On the basis of the analysis of the experimental data, the sensitivity of the embrittlement of 7075-T6 aluminum alloy by liquid gallium to the loading strain rate is significantly higher compared to other environmental factors. In addition, this study also includes several experiments for microscopic observation, such as Scanning Electron Microscope (SEM) observation, Energy-Dispersive Spectrometer (EDS) spectroscopy, and Electron Back Scatter Diffraction (EBSD) analysis. The experimental observations confirmed the following: (1) gallium is enriched in the intergranular space of aluminum; (2) the fracture mode of 7075-T6 aluminum alloy changes from ductile to brittle fracture; and (3) the infiltration of liquid gallium into aluminum alloys and its enrichment in the intergranular space result in the formation of new dislocation nucleation sites, in addition to the original dislocations cutting and entanglement. This reduces the material's ability to undergo plastic deformation, intensifies stress concentration at the dislocation nucleation point, and, ultimately, leads to the evolution of dislocations into cracks.

Evaluating the impact of bentonite granule size distribution and swelling on the hydraulic conductivity of geosynthetic clay liners

The impact of granular size, distribution, total intergranular porosity, mobile intergranular porosity, and the tortuosity of the flow paths on the hydraulic conductivity of geosynthetic clay liners (GCLs) was assessed using a COMSOL hydrodynamic model. Results showed that as the intergranular pore spaces become smaller as the bentonite granules swell, the hydraulic conductivity of the GCL decreases. This effect is more significant when the density of the bentonite is lower. Outcomes from the model also illustrate that flow in GCLs with low hydraulic conductivity occurs in fine pore spaces with a width on the order of 1 um. The mobile intergranular porosity through which flow occurs is approximately 0.05 after the bentonite swells, and is small relative to the total intergranular porosity. This indicates that most water within bentonite having low hydraulic conductivity is occluded within isolated pores. As the hydraulic conductivity decreases, the tortuosity of intergranular flow paths increases, varying from 1.38 to 1.03. The findings provide insight into the complex flow behavior in GCLs and factors that affect achieving low hydraulic conductivity.

Granite Crushing Screenings as a Component Factor in the Concrete Structure Formation. Part II: Experimental Studies of Structure-forming Potential

The paper considers the results of experimental studies of the individual and joint influence of macro-, meso- and micro-nanofractions of granite crushing screenings on the processes of structure formation and properties of cement concrete. It has been established that in the processes of formation of the structure of fine-grained concrete and the potential for resistance to its destruction, all fractions of stone crushing screenings perform their specific functions as a component factor. Macro-sized (crushed stone) grains of screening of the 5–10 mm fraction form a macro-scale frame of the addition system, which perceives force load with the accumulation of loading energy and braking of main cracks. Sand mesoparticles of fraction 0.16–5 mm fill the intergranular space of the system for adding macroparticles with dissipation of external loading energy in the matrix material. The microfraction of granite crushing screenings (the fraction is <0.16 mm), along with the effect of replacing the volume of cement stone, exhibits physical and chemical activity in the phase formation of hydrate compounds. It is shown that in the initial screening of granite crushing, the structure-forming role of its particles is not manifested effectively enough, the main reason for which is the “excess” of sand fractions, which push apart the grains of macrofractions and increase the water demand of the concrete mixture. Traditional methods of enriching screenings do not solve this problem. The principle of conditioning screenings by saturating them with macro- and micro-sized fractions is discussed. Based on this principle, a technology for mechanical processing of screenings has been developed to produce a “line” of products for targeted use in the building materials and products industry. The introduction of such technology will significantly increase the efficiency of construction and technological recycling of stone crushing screenings through maximum use of the structure-forming potential of their polydisperse composition.

Effect of Σ5(2 1 0)[0 0 1] symmetric tilt grain boundary on the compatibility between iron and liquid lithium: Atomistic simulations

The compatibility between Fe-based alloys and liquid Li is crucial for the development of liquid Li blanket in the fusion devices. In this work, molecular dynamics (MD) simulations have been used to reveal the effect of Σ5(210)[001] symmetric tilt grain boundary (GB) on the compatibility between Fe and liquid Li. The results show that the corrosion of Fe bicrystal by liquid Li aggravates with increasing temperature, and the critical temperature for the deterioration of compatibility is about 800 K. In the corrosion process, the Fe atoms near the GB are most likely to escape or even dissolve, and Li atoms preferentially penetrate into the intergranular space along the GB. Based on the simulation, the Fe atoms near the GB have high potential energy and poor structural ordering, and their thermal motion at high temperatures generates a large number of Frenkel defects here, which in turn promote the diffusion of Fe and Li atoms along the GB. In terms of energetics, the lower vacancy formation energies and Li atomic substitution energies near the GB are responsible for the GB corrosion.

Stress sensitivity of permeability in high-permeability sandstone sealed with microbially-induced calcium carbonate precipitation

Microbially induced carbonate precipitation (MICP) catalyzed by S. pasteurii has attracted considerable attention as a bio-cement that can both strengthen and seal geomaterials. We investigate the stress sensitivity of permeability reduction for the initially high-permeability Berea sandstone (initial permeability ∼110 mD) under various durations of MICP-grouting treatment. The results indicate that after 2, 4, 6, 8 and 10 cycles of MICP-grouting, the permeabilities decrease incrementally by 87.9%, 60.9%, 38.8%, 17.3%, and then 5.4% compared to the pre-grouting condition. With increasing the duration of MICP-grouting, the sensitivity of permeability to changes in stress gradually decreases and becomes less hysteretic. This stress sensitivity of permeability is well represented by a power-law relationship with the coefficients representing three contrasting phases: an initial slow reduction, followed by a rapid drop, culminating in an asymptotic response. This variation behavior is closely related to the movement and dislocation of the quartz framework, which is controlled by the intergranular bio-cementation strength. Imaging by scanning electron microscopy (SEM) reveals the evolution of the stress sensitivity to permeability associated with the evolving microstructures after MICP-grouting. The initial precipitates of CaCO3 are dispersed on the surfaces of the quartz framework and occupy the pore space, which is initially limited in controlling and reducing the displacement between particles. As the precipitates continuously accumulate, the intergranular slot-shaped pore spaces are initially bonded by bio-CaCO3, with the bonding strength progressively enhanced with the expanding volume of bio-cementation. At this stage, the intergranular movement and dislocation caused by compaction are reduced, and the stress sensitivity of the permeability is significantly reduced. As these slot-shaped pore spaces are progressively filled by the bio-cement, the movement and dislocation caused by compaction become negligible and thus the stress sensitivity of permeability is minimized.

Исследование возможностей снижения энергоемкости адсорбционных процессов при высоких требованиях к влагосодержанию сжатого воздуха

Purpose: Study of the possibility of reducing the energy intensity of adsorption processes with high requirements for the moisture content of compressed air. Results: It has been shown that the molecular sieve RS-144M has the lowest weight among all the adsorbents represented due to its low density, which makes it possible to reduce the weight of the adsorption unit; the smallest volume and height of adsorption filling in the column have zeolites NaA and Ka-CO, followed by molecular sieves; due to the release of the molecular sieve RS-144M in the form of a powder the size of the working pores of 3Å, it has a low bulk density and the smallest intergranular spaces, which provides a low value of porosity of the granules, a total of 8.3% of the total fill volume. Practical significance: The use of molecular sieves produced on the basis of zeolite helps to reduce the energy capacity of the compressed air drying process. The most effective is the molecular sieve RS-144M. It allows you to dry compressed air to meet the requirements of the highest moisture purity classes, while guaranteeing the lowest energy consumption. The remaining adsorbents will also allow the compressed air to be dried to the desired purity grade, but will have an energy consumption greater than that of the RS-144M, making their use not always expedient.

Remobilization of HFSE, Y, and REE during Diagenetic Alteration of Heavy Minerals in Sandstones from the Chvalčov Site, Flysch Belt of the Outer Western Carpathians, Czech Republic

An in situ electron microprobe study of detrital minerals yielded important insights into the diagenetic history of the Cretaceous-to-Paleogene flysch sandstones from the Chvalčov site, Rača Unit, Flysch Belt of the Outer Western Carpathians. Detrital titanite and a Fe-Ti mineral (probably ilmenite) were almost completely altered to TiO2 minerals, which also newly crystallized in intergranular spaces of sandstone. Brookite, anatase, and, exceptionally, rutile were identified by Raman spectroscopy. Authigenic TiO2 phases show complex composition with occasionally elevated contents of Fe, Nb, Zr, V, Sc, Cr, Al, Y, and/or P, which were likely sourced from altered neighboring heavy minerals. In addition, rare authigenic LREE- and Y-enriched apatite rims were observed on detrital apatite. The remobilization of REE, Y, and HFSE was likely mediated by acidic early diagenetic fluids enriched in fluoride and sulfate anions. The superimposed formation of calcite cement was associated with the dissolution of detrital garnet, feldspars, and quartz. The compositions of detrital apatite and garnet (Alm60-82Prp4-30Sps0-24Grs0-19) are comparable with those from adjacent parts of the Flysch Belt. Detrital rutile is enriched in Nb, V, Cr, and Zr. Our study illustrates the intensity of diagenetic alteration of detrital minerals in flysch sandstones as well as the usefulness of in-situ electron-microprobe investigations for the recognition of processes influencing heavy minerals in diagenetically altered sediments.

SiC fiber strengthened Si[sbnd]14Ti high-temperature filler alloy for brazing SiCf/SiC and C/C composites

SiC fibers were employed as the reinforced and tough phase in the Si14Ti filler alloy for joining SiCf/SiC composites and C/C composites. The joint microstructure and regulation mechanism of SiC fibers were investigated for the first time. The morphology evolution of SiC fibers was also observed through the chemical reaction experiment between fibers and liquid Si14Ti alloy. SiC nanocrystals that composed the SiC fibers experienced degradation and regrowth progress in the high-temperature Si14Ti melt, and then transformed into coarse SiC in the brazing seam. Meanwhile, the liquid Si14Ti filler alloy filled the intergranular space among the newly generated SiC blocks, and reacted with the SiCf/SiC and C/C composites to form SiC interfacial layers. The microstructure of the SiCf/SiC-C/C joint finally evolved into SiC interfacial layer/SiC-TiSi2 multi-phase ceramics and Si-TiSi2 eutectic structure/SiC interfacial layer. Finally, a favorable joint shear strength of 48 MPa was obtained when brazing at 1420 °C.

TWO TYPES OF GALLIUM EXPOSURE TO ALUMINUM

The effect of gallium on aluminum during their fusion is investigated. The corrosion rate of aluminum alloys with 1, 2 and 5 at % gallium content was experimentally determined, which was 0.001, 0.00101 and 0.00062 g/m2 · h, respectively, which is less than that of pure grade A99 aluminum – 0.0016 g/m2 · h. The rate of dissolution of these alloys in acidic and alkaline media is determined. X-ray phase analysis showed the homogeneity of the alloys under consideration. The morphology of aluminum alloys with gallium was studied, after exposure to an aggressive environment – a solution of hydrochloric acid. The possibility of obtaining hydrogen and nanoscale alumina by decomposition of water by activated gallium aluminum alloy is shown. Activation of the aluminum surface by gallium alloy occurs according to the Rebinder effect and the article presents a micrograph of the surface of aluminum treated with Ga-Sn alloy, clearly demonstrating this effect. When using metallic gallium in contact with aluminum, the interaction requires heating to a temperature above 30°C (the melting point of gallium is 29.7°C), the melting point of the eutectic composition 92Ga–8Sn is 20.0°C, which allows the interaction to begin at room temperature. At temperatures of about 4°C, activated aluminum can be stored for a long time. The quality of hydrogen obtained by decomposition of water should be higher than that obtained by cracking, and the cost is close to a well-developed technology of electrolysis of water and no more than 2 times the cost of its synthesis via cracking of hydrocarbons. Gallium and its liquid alloys are non-toxic, almost do not interact with water, activate aluminum, preventing the formation of a protective oxide film, penetrate into the intergranular space and aluminum easily interacts with water, forming hydrogen and aluminum hydroxide.