Aqueous Solution Of Boric Acid Research Articles

Ultrahigh-Temperature Long-Persistent Luminescence from B2O3-Confined Polycyclic Aromatic Compounds.

Organic molecules and polymers have recently been intensively explored for afterglow materials owing to their low cost and flexible design. However, they normally fail to generate long-persistent luminescence at elevated temperatures, mostly due to the fast deactivation of triplet excited states. Here, we report that polycyclic aromatic compounds (PACs) individually confined in a B2O3 crystalloid emit long-persistent luminescence at high temperatures up to 400 °C. This is facilely accomplished by dispersing a series of aromatic derivatives in an aqueous solution of boric acid, followed by drying, melting, and dehydrating. The resulting highly rigid and thermostable B2O3 crystalloid network provides a matched ultrastrong confinement effect and completely restricts the vibration and rotation of the molecularly distributed PACs even at ultrahigh temperatures and thereby prevents the nonradiative dissipation of triplet excitons and promotes the generation of ultrahigh-temperature long-persistent luminescence. The afterglow colors are responsive to both temperature and time, spanning from ultraviolet to near-infrared regions over a wide temperature range, which is substantially modulated by the subtle balance of phosphorescence and thermally activated delayed fluorescence. These features favor the creation of advanced afterglow materials for visual 3D temperature probing, anticounterfeiting, and data encryption in extreme environments.

Ti compound coating of carbonyl iron particles with controlled surface conditions using a peroxotitanium acid solution for stable magnetic particles

The surface coating of carbonyl iron particles (CIPs) deposited under various surface conditions was examined using a peroxotitanium acid (PTA) solution including H2O2 to obtain highly stable magnetic particles. Upon adsorption on the CIP surfaces, peroxotitanium complexes dehydrated and transformed into TiO2 with hydroxides (TiO2–OH), and the coating morphology significantly changed depending on the surface conditions of the CIPs. The volatile surface impurities that remained on raw CIPs inhibited the adsorption of the complexes, leading to insufficient coating. As oxidation treatment using a boric acid aqueous solution was performed to examine the effects of surface oxides on the coating, the treatment increased the oxide layer thickness and specific surface area of the raw CIPs. During the coating of oxidized CIPs, active surfaces were dissolved in a PTA solution, and γ-FeOOH plate particles were redeposited on the particle surfaces because H2O2 remaining in the PTA solution initially oxidized the active surfaces and then depleted. The results indicated that the treatment with the PTA solution was not suitable for oxidized CIPs with increased specific surface area. A simple dry treatment under vacuum conditions decreased surface impurities on raw CIPs without increasing their specific surface area; consequently, their surfaces were uniformly and sufficiently coated with TiO2–OH. The uniform surface coating decreased the saturation magnetization of the CIPs by only 0.98% and improved their oxidation onset temperature from 369.8°C to 437.1°C, making them suitable for practical use.

Harnessing the antimicrobial potential of natural starch and mint extract in PVA-based biodegradable films against staphylococcus aureus bacteria

Sustainable packaging solutions are of paramount importance in addressing the environmental challenges posed by conventional non-biodegradable materials. This study addresses this critical need by introducing a novel approach to crafting antimicrobial biodegradable polymer films. Leveraging the benefits of polyvinyl alcohol (PVA) as a base material, combined with corn-starch (CS) and mint extract (ME), these films offer a compelling synergy of eco-friendliness, antimicrobial efficacy, and mechanical strength. The antimicrobial property was imparted by adding mint extract, and boric acid (BA) was added as a cross-linker for better mechanical properties. All process was done by solution casting method followed by mechanical stirring. After 7 days, starch-PVA blend showed 50% weight loss; however, after adding mint extract, the action of microbes was reduced, and a 50% reduction in weight was observed after 12 days. The excellent mechanical properties were achieved by adding 10% aqueous solution of BA as a cross-linker. The confirmation of BA in the blend was done by the Fourier transform infrared spectroscopy (FTIR). Differential scanning calorimetry (DSC) was used to check the thermal properties of the films. Antimicrobial results showed that mint extract was resistant to staphylococcus aureus bacteria. These biodegradable films offer a multifaceted solution, aligning with sustainability objectives, showcasing antimicrobial potential, and demonstrating mechanical robustness. As such, they hold promise for a diverse array of applications, particularly in the realm of environmentally conscious food packaging. In the pursuit of greener alternatives, these films stand as a testament to innovative materials engineering that harmonizes functionality with ecological responsibility.

Preparation and Boron Removal Performance of Glycidol Modified PANI Nanorods: An Optimization Study Based on Response Surface Methodology.

Boron removal from aqueous solutions has attracted increasing attention, offering benefits for animal and plant health as well as profound significance for exploiting Salt Lake boron resources. In this work, we synthesized novel glycidol-functionalized and hydrophilic polyaniline (PANI) nanorod adsorbents, which were prepared to separate boron compounds from boric acid aqueous solutions. The as-prepared adsorbents were significantly different from the traditional polymers' grafting reaction because they had a higher functional yield and more active position for adsorption. The maximum adsorption capacity (0.2210 mmoL∙g-1) and optimal adsorption conditions (boric acid concentration of 1307 mg/L, pH = 9.82, time of 10 h) were obtained with single-factor experimentation and the response surface method (RSM). In addition, adsorption kinetics studies showed that the adsorption reaction belonged to the pseudo-first-order kinetic model, and diffusion was the key limiting factor; therefore, the adsorption equilibrium time is more than 10 h. Finally, the related possible adsorption mechanism was investigated based on the species and the diffusion of boron in the aqueous phase.

Volatility of boric acid in water: New experimental data below 373.15 K and reassessment of equilibrium constant models

A data review for vapour liquid equilibrium (VLE) of the boric acid/ water system is conducted from different databases and authors. A void of information for the distribution coefficient for boric acid into the liquid and vapour phases at temperatures below 373.15 K is identified. New experimental data is measured in this work to fill the lack of distribution coefficients values for temperatures below 373.15 K. Values calculated from mathematical correlations for the distribution coefficient are compared with the experimental data. Besides, mixed solvent electrolyte thermodynamic model (MSE) has been computed for VLE equilibrium based on a gamma–phi formulation; thus, it includes a calculation of the speciation equilibrium for boric acid in aqueous solutions. Nevertheless, actual parameters used in MSE model are not adapted to represent the distribution coefficient at temperatures below 500 K. Consistency is evaluated between experimental data and thermodynamic correlations. The correlation presented by Plyasunov (2011) is identified as the correlation that represents the experimental data with less variation among the collected correlations. Finally, a modification in the parameters of volatility for MSE model is proposed to obtain a similar representation of the distribution coefficient than the correlation proposed by Plyasunov (2011).

Влияние растворов борной кислоты в органических растворителях на продуктивность и химический состав зеленой массы клевера лугового

A comparative study of the effectiveness of boron in various forms (aqueous solution / chelated form) on the yield and quality indicators of Martum variety meadow clover herbage was carried out. Chelated forms were solutions of boric acid in organic liquids: monoethanolamine, diethanolamine, triethanolamine, glycerol, ethylene glycol. The plants fertilized with solutions of boric acid in orga¬nic solvents were bulkier and their biomass grew more intensively. The use of an aqueous solution of boric acid (the traditional form of boron microfertilizers) increased the plant growth by only 6.2 % compared to the variant without fertilization. The use of organic solvents led to more significant increase in the height of red clover: its increase compared to control test varied from 5.5 to 19.6 cm. The tallest plants were observed in the variant with the use of boric acid dissolved in ethylene glycol, which exceeded the control value by 1.3 times. Foliar top dressing with boric micronutrient fertilizers allowed increasing the herbage of the experimental crop by 7.4–78.5 %, in relation to the control test. The use of triethanolamine, glycerol, and ethylene glycol as solvents contributed to the maximum significant growth of the vegetative mass of clover, which was 8.1, 7.7 and 9.5 t/ha higher, respectively, compared to the unfertilized variant. The collection of dry matter in the experimental variants increased by 0.1–1.1 t/ha. The highest value of this indicator was noted during foliar treatment of clover with the solution of boric acid based on ethylene glycol, which exceeded the value of the control test by 73.3 %, as well as the variant with an aqueous solution of boric acid by 62.5 %. In addition to taking into account the total content of organic or mineral compounds in the clover phytomass, the content of the main nutrients – nitrogen, phosphorus, and potassium – was determined. The highest concentration of nitrogen was observed after adding a mixture of boric acid and glycerol, which is 24.2 % higher than the value in the control test, as well as 33.1 % higher than the variant after the aqueous solution of boric acid. The content of phosphorus in the clover herbage was maximal in the variant using a solution of boric acid in glycerol; it exceeded the control test by 15.4 %. The dissolution of boric acid in water and ethylene glycol, on the contrary, significantly reduced the concentration of this element by 11.5 % compared to the control test. The content of potassium in the clover herbage in the control test was 1.95 %, while the use of solutions of boric acid in organic solvents for foliar feeding led to an increase in this indicator by an average of 1.04 times. At the same time, the maximal increase in the indicator under consideration in the variant where a solution based on diethanolamine was used equaled 7.7 % to the corresponding value of the unfertilized variant and 8.2 % to the variant using an aqueous solution of boric acid. The use of boric acid contributed to a slight decrease in the content of nitrates, and the options with the use of di- and triethanolamine were characterized by the greatest effect in this case.

Non-negligible corrosion from vaporized boric acid on 304 stainless steel

Based on the volatility and sublimation properties of boric acid, the corrosion behaviours of 304 stainless steel (SS) in boric acid-containing vapour over the boric acid aqueous solution and in the solution at high temperature were investigated. The results showed that the vaporized boric acid could cause or accelerate the formation of droplet-orientated scabs on the metal surfaces, which led to the formation of localized crust-like layers of corrosion products, whereas the boric acid in solution could only cause uniform corrosion with thin oxide layers formed on the metal surface. Prolonging the exposure duration or increasing the concentrations of boric acid in solution could accelerate the localized corrosion. The weight gains of 304 SS exposed to the vaporized boric acid reached 0.314 mg/cm2 at 180 °C for 960 h, while it was 0.055 mg/cm2 in the corresponding boric acid solution, being 5.7 times in weight changes. Furthermore, the possible corrosion pathway and formation mechanism of the corrosion products were proposed and discussed.

Anodizing of Hydrogenated Titanium and Zirconium Films.

Magnetron-sputtered thin films of titanium and zirconium, with a thickness of 150 nm, were hydrogenated at atmospheric pressure and a temperature of 703 K, then anodized in boric, oxalic, and tartaric acid aqueous solutions, in potentiostatic, galvanostatic, potentiodynamic, and combined modes. A study of the thickness distribution of the elements in fully anodized hydrogenated zirconium samples, using Auger electron spectroscopy, indicates the formation of zirconia. The voltage- and current-time responses of hydrogenated titanium anodizing were investigated. In this work, fundamental possibility and some process features of anodizing hydrogenated metals were demonstrated. In the case of potentiodynamic anodizing at 0.6 M tartaric acid, the increase in titanium hydrogenation time, from 30 to 90 min, leads to a decrease in the charge of the oxidizing hydrogenated metal at an anodic voltage sweep rate of 0.2 V·s−1. An anodic voltage sweep rate in the range of 0.05–0.5 V·s−1, with a hydrogenation time of 60 min, increases the anodizing efficiency (charge reduction for the complete oxidation of the hydrogenated metal). The detected radical differences in the time responses and decreased efficiency of the anodic process during the anodizing of the hydrogenated thin films, compared to pure metals, are explained by the presence of hydrogen in the composition of the samples and the increased contribution of side processes, due to the possible features of the formed oxide morphologies.

A new approach to the synthesis of nanosized powder CaO and its application as precursor for the synthesis of calcium borates

A procedure for the synthesis of calcium oxide has been developed, which consists in heat treatment of an aqueous solution of calcium acetate and d-glucose at 350 and then at 700 °C. The process parameters have been determined. It has been shown that when d-glucose is used and the reaction mixture is heat treated at 700 °C, highly dispersed calcium oxide with an average particle size of 77 nm is formed. CaO formed has been used as a precursor for the synthesis of priceite (Ca2(B5O7)(OH)5 · H2O) during hydrothermal treatment of CaO in an aqueous solution of boric acid. It has been found that the optimal conditions for the synthesis of monophase priceite under hydrothermal conditions include the temperature range of 170–200 °C and the heating time of 12 h. When heating priceite at 800 °C in air for 1 h, highly dispersed powder calcium bis(borate) Ca(BO2)2 has been isolated as the final product. It is shown that the use of synthesized powder CaO leads to the formation of fine-crystalline powders of calcium borates. Samples obtained at each stage of the proposed synthesis of highly dispersed calcium oxide and calcium borates, using the example of priceite and calcium bis(borate), have been studied by powder X-ray diffraction, SEM, TEM, BET, IR spectroscopy, and DTA.

ОПРЕДЕЛЕНИЕ КОМПЛЕКСА ТЕПЛОФИЗИЧЕСКИХ СВОЙСТВ ВОДНЫХ РАСТВОРОВ БОРНОЙ КИСЛОТЫ ПРИ ПАРАМЕТРАХ ХАРАКТЕРНЫХ ДЛЯ АВАРИЙНОГО РЕЖИМА ВВЭР

The article presents the results of experimental studies of the thermophysical (density, viscosity) and physicochemical (degree of acidity - pH) properties of water solutions of boric acid. A review of the available literature data on the effect of the properties of boric acid solutions on heat removal from the reactor core is presented. It has been established that the available information is very general and does not cover the entire range of parameters (temperature, pressure, acid concentration) characteristic of a possible emergency at a nuclear power plant with a VVER reactor. Methods and facilities for conducting experimental studies are described. The results of experimental studies are presented. The density of aqueous solutions of boric acid with a concentration of 2.5-450 g/kg H2O at a temperature of 25-130 °C was determined. The dependence of the investigated characteristic on temperature and concentration was also obtained. The results of an experimental study of the kinematic viscosity of water solutions of boric acid with a concentration of 2.5-200 g/kg H2O at a temperature of 25-90 °C were obtained. The total error in measuring the viscosity of aqueous solutions of boric acid did not exceed 2 %. The pH values of water solutions of boric acid in the temperature range 25-50 and concentrations of 2.5-450 g/kg H2O were determined. The dependence for calculating the degree of acidity of boric acid is obtained. Experimental data on the thermophysical and physicochemical properties of water solutions of boric acid can be used to refine the results of calculations of emergency heat removal processes in a reactor facility, carried out using both one-dimensional calculation programs and three-dimensional CFD codes.

Development of coalescents for paints and varnishes based on ionic liquids – the products of diethanolamine and inorganic acids interaction

This paper reports the synthesis of ionic liquids through the interaction between diethanolamine and orthophosphate and boric acids in order to establish the possibility of replacing volatile coalescents in a formulation for paints and varnishes with ionogenic compounds. The results from studying the influence of polymeric coalescents based on ionic liquids on the rheological properties of water-dispersion paints and varnishes of different nature are presented. It has been established that the synthesized coalescents could be used to modify the properties of paints and varnishes based on polyurethane and styrene-acrylic aqueous dispersions. It has been shown that the product of the interaction between diethanolamine and boric acid in aqueous solutions forms an ionogenic complex compound with a unipolar conductivity in terms of ОН─ ions. It was also established that when introduced to the formulation of water-dispersion paints and varnishes, the solutions of modifiers produce a diluting action. The influence of ionic liquids on the process of film formation of aqueous dispersions of polymers and pigmented paints and varnishes based on them was investigated. It was established that the synthesized ionogenic compounds are not inferior, in terms of their effectiveness, to the widespread conventional industrial coalescents of the Texanol→ type. Therefore, there is reason to assert the possibility of replacing the industrial coalescent Texanol→ in the formulation of pigmented water-dispersion paints and varnishes based on styrene-acrylic and polyurethane dispersions with fundamentally new synthesized ionogenic modifiers. Thus, the coatings with a coalescent based on ion liquid of diethanolamine borate have a higher level of conditional hardness, which exceeds by 17 % the hardness index of the paint made on the basis of the conventional Texanol→ type coalescent, without changing its decorative properties, such as color and shine

Modeling of the Refractive Index for the Systems MX+H2O, M2X+H2O, H3BO3+MX+H2O, and H3BO3+M2X+H2O. M = K+, Na+, or Li+ and X = Cl− or SO42−

The modeling of the refractive index for binary aqueous solutions of boric acid, sodium chloride, potassium chloride, sodium sulfate, lithium sulfate, and potassium sulfate, as well as ternary aqueous solutions of boric acid in the presence of sodium sulfate, lithium sulfate, or potassium chloride, is reported. The refraction index was represented by molar refraction. It was described as the sum of solutes’ partial molar refraction and solvent molar refraction. The solutes’ partial molar refraction was estimated from the molar refraction of the binary solutions. The excess molar refraction for these systems was described with the equation of Wang et al. The polarizability of the solutes present in the studied systems was estimated using the Lorenz–Lorenz relation. The results showed the model is appropriate for describing the systems studied; the interactions of boric acid, sodium, potassium, lithium, chloride, and sulfate ions with water molecules are relevant to explain the molar refraction and refractive index, and those for the binary systems of lithium chloride and sodium chloride are also relevant the ion–ion interactions. The model is robust and presents estimation capabilities within and beyond the concentrations and temperature range studied. Therefore, the outcomes represent valuable information to understand and follow the industrial processing of natural brines.

Использование растворов борной кислоты в орга-нических жидкостях в качестве борсодержащих микро-удобрений. Влияние на урожайность и химический состав зерна озимой и яровой пшеницы

The conditions for dissolution of boric acid in monoethanolamine, diethanolamine, triethanolamine, glycerol, ethylene glycol and morpholine were selected, which made it possible to obtain low-viscosity solutions with a concentration that was many times higher than the max-imum attainable concentration in water and did not produce precipitates during storage. The resulting solutions were used as microfertilizers for foliar feeding and seed treatment of win-ter (Moskovskaya 56) and spring (Zlata) wheat. The use of boron as a microelement contributed to the preservation of a larger number of living plants of winter wheat during the wintering peri-od, and, consequently, the better winter hardiness of the crop. The maximum value of the winter wheat yield was obtained when the seeds were treated with monoethanolamine borate. The high-est values of the indicators of the yield structure belonged to the grain of winter wheat against the background of the seed treatment with a chelated form of boron: for the number and weight of grains when monoethanolamine borate was used; for the length of the ear when glycerol borate was used. The treatment of the Moskovskaya 56 wheat seeds with the microelement led to an increase in the amount of nitrogen in the grain relative to the control by 7–11 %. The highest values belonged to the variants including the treatment of seeds with the traditional form of the element (aqueous solution of boric acid), as well as the treatment with monoethanolamine borate. The maximum increase in the yield of the Zlata spring wheat was observed on feeding with a solution of boric acid in glycerol: 3.26 t / ha (2.1 times higher than on feeding with the traditional form of the microelement). Boron as a microelement contributed to an increase in the structural parameters of spring wheat plants in all forms. The greatest positive effect was noted from the action of glycerol borate, where the difference to the control variant was 2.4 times for the number of grains in an ear to the control, and their weight was 2.7 times. After the use of boron the spring wheat gluten was characterized as good (quality group I).

Динамика сорбции борной кислоты борселективным анионитом типа СБ

Investigation and choice of an effective sorbent are significant for protection of water bodies against boron The boron high concentration in natural waters produces toxic impact on aquatic biota due to its high biological activity. This paper studied the dynamics of boric acid sorption from aqueous solutions by polycondensation anionite SB-1 synthesized on the base of monoethanolamine and epichlorohydrin. The anion exchanger contained aminooxyethyl and alcohol functional groups in its structure. Methods. It has been established the influences of the ion form of the anionite on the dynamic characteristics of boron sorption from both a model boric acid aqueous solution (0.43 mol/dm3) and an industrial wastewater effluent after boric acid production (0.47 mol/dm3), other things being equal (pH = 5.0; the volume rate of the solution passing through the anionite layer = 1.5 ml/min∙cm2; t = 20 0C). Structural studies to determine the form of boron in the anionite phase were performed using the IR spectroscopic method. Dynamic characteristics of boron sorption (the cation and overall ion-exchange capacity values, period of the protecting effect of the filter) were determined graphically from the sorption curves. Results. It has been found that the hydroxyl form of the anion exchanger SB-1, in comparison with the chlorine form, performs superequivalent boron sorption while boron sorption from both a model and real production solutions. For the first time we have demonstrated that at the initial stage, boric acid sorption is carried out owing to the chemisorption, resulting to the formation of stable hydroxoborate forms [B(OH)4]– in the ionite phase. As the anionite is being saturated and the concentration of free functional hydroxyl groups is decreasing, the formation of polynuclear forms of boric acid [B4O5(OH)4]2– occurs in the anionite phase by sorption of boric acid molecules on free tetrahydroxoborate anions and, further, the complex formation of polynuclear forms of boron by the nitrogen atom of aminooxyethyl functional groups. It has been stated that desorption of boron from anionite is considered to be effective when carried out with a 2 n. NaOH solution with a regeneration degree of 0.995.

Experimental study of the surface tension of highly concentrated boric acid solutions applicable to VVER emergency cooling

The results of the experimental studiesof the surface tension of aqueous solutions of boric acid in a range of concentrations of 2.5-150 gkg−1H2O are presented in the paper.As a result of a literature review, it was foundthe present information about surface tension of boric acid solutions is contradictory and does not cover the entire range of parameters characteristic of a possible emergency at nuclear power plants (NPPs) with the VVER reactor. The technique of the experimental research is described. The results of the measurements of the surface tension of aqueous solutions of boric acid are presented.The existence of the temperature dependence is confirmed.The effect of concentration on the surface tension of aqueous solutions of boric acid in the studied range of parameters is shown.

Theoretical Study on Ionization of Boric Acid in Aqueous Solution by Ab Initio and DFT Methods at T=298.15 K.

The aim of this research work was to theoretically calculate the pKa value of boric acid in aqueous solution by theoretical methods at T=298.15 K. Boric acid has antifungal and antiviral properties. It is used in various prescription pharmaceutical products. The ab initio and density functional theory (DFT) methods were used in this research work. To explain the determined acidic dissociation constant, the various molecular conformations and solute-solvent interactions of the species of boric acid were considered. The basis set at the B3LYP/6-31+G (d) level of theory was selected for DFT calculations. We analyzed the formation of intermolecular hydrogen bonds between several species of boric acid and water molecules through Tomasi's method. The result showed that there was comparable agreement between the experimentally and theoretically determined pKa values for boric acid.

Rate-based simulation study of boric acid promoted potassium carbonate capture system

This study presents parametric analysis and process modification on a post-combustion carbon dioxide (CO2) capture system using boric acid promoted potassium carbonate (K2CO3) solution. The model was simulated in Aspen Plus® V10 and ELECNRTL property package was employed. Un-promoted K2CO3 system was adopted as a base case study and its simulation was validated using literature data. The K2CO3 concentration in the lean solvent makeup was then varied from 25 wt% to 40 wt% to examine the effects of lean solvent concentration on key operating variables such as stripper reboiler duty, stripper condenser duty and CO2 capture rate. A 2 wt%, 4 wt% and 6 wt% aqueous boric acid solutions were then added as promoter to the hot K2CO3 solvent and the simulation results indicated that capture rate efficiency can be enhanced by 0.7%, 0.9% and 1.2% respectively. Energy saving process modification was also carried out to the stripper column. Compared to the conventional unmodified H3BO3/K2CO3 system, the modified promoted system is able to achieve 21.09% savings in reboiler duty.

Studying the thermophysical and physicochemical properties of solutions of boric acid for emergency core cooling of WWER

The results of experimental research of physicochemical (degree of acidity - pH) properties of aqueous solutions of boric acid are presented in this paper. A review of available literature data about the influence of properties of boric acid solutions on heat removal from the reactor core is given. It has been established that the available information is very general in nature and does not cover the entire range of parameters (temperature, pressure, acid concentration) characteristic of a possible emergency situation at NPPs with a WWER reactor. Experimental techniques and test facilities for research are described. The experimental data of the pH of aqueous solutions of boric acid in range of the concentration (5-100 g kg-1 H2O) and temperature (25-50 °C) are received. The approximating dependence for the degree of acidity of aqueous solutions of boric acid has been obtained.

Simulation of particle size distribution of mechanochemically activated charges of Al-SiC composite materials

Annotation. In this work, 3D Spline models of the influence of silicon carbide content on the particle size distribution of the powder mechanochemical activated mixture Al-SiC were built. The formation of agglomerates in the process of mechanochemical activation (MCA) of a multicomponent Al-SiC mixture in a liquid medium of a saturated aqueous solution of boric acid has been established. The increase in the content of SiC in the charge increases the degree of agglomeration of the composite particles of the powder mixture in the process of MCA. Subsequent manual processing leads to the grinding of agglomerates and a change in the distribution of particle sizes from bimodal to unimodal distribution. The parameters of the constructed nonlinear model of the particle size distribution of mechanochemically activated Al – SiC powder blends (5–20 wt.%) Are determined. At the optimum content of silicon carbide (10% wt.), The relationship between the extreme values of the model parameters and the maximum hardness of the hot-compacted composite Al-SiC powder was established.

Thermodynamics of Polyborates under Hydrothermal Conditions: Formation Constants and Limiting Conductivities of Triborate and Diborate

Frequency-dependent molar electrical conductivities for aqueous solutions of boric acid with small additions of sodium hydroxide or potassium hydroxide have been measured from 298 to 573 K at 12 MP...