Glass Physics and Chemistry最新文献

Development of value-added utilization method for rice husk char (RHC) generated from rice husk gasification power plants is desirable. Amorphous porous silica was obtained by simple calcination of RHC; however, acid treatment prior to calcination improved its purity and increased its specific surface area. In the adsorption of Methylene Blue (MB) by the prepared porous silica, acid treatment enhanced its adsorption capacity and suppressed the increase in the pH of the MB solution. According to the Langmuir adsorption isotherm, the maximum adsorption capacity of the porous silica obtained by calcining acid-treated RHC at 500°C was 26.81 mg/g, which was 3.5 times higher than that of the porous silica obtained by calcining RHC at 500°C without acid treatment.

A new composite material based on thermoplastic elastomer is developed for the 3D printing of neutron-absorbing products. It is shown that the use of thermoplastic elastomer in the development of material for the 3D printing of products allows for the required neutron absorption properties to be achieved, significantly increasing the technological effectiveness of the composition and preserving its applicability in additive technologies. The concentration of boron nitride in the composite, which allows achieving the effect of absorption of neutron radiation by the material of 2.4 Å/1.2 Å (3/1) to a penetration depth of 1.4 mm, while maintaining its physical and mechanical properties, was 25%. The physical and mechanical characteristics of the developed material are not inferior to unfilled plastics: tensile strength σ_max = 8.1 MPa and tear resistance T_s = 76 N/m.

Three borosilicates with the general formula of REE₃BSi₂O₁₀ (REE = Nd, Eu, Gd) were obtained by the high-temperature solid-state synthesis and studied by powder high-temperature X-ray diffraction (HTXRD) in the temperature range from 30 up to 1050°C. The HTXRD study showed that these borosilicates (orthorhombic, Pbca space group) have similar, nearly isotropic thermal expansion in the whole temperature range; the average coefficients of thermal expansion (CTE) were: 〈α_a〉 = 9.6, 〈α_b〉 = 8.3 and 〈α_c〉 = 8.7 × 10^–6°С^–1, with (α_max – α_min) ≤ 1.2 × 10^–6°С^–1. The average volume CTE insignificantly decreases with increasing the cation size from 27.2 for Eu and 27.0 for Gd down to 25.8 × 10^–6°С^–1 for Nd compound while the unit cell volume increases with increasing the REE cation radii in the REE₃BSi₂O₁₀ series.

Amidst the relentless surge in demand for fiberglass products in recent years, a concomitant rise in product remnants and obsolete fiberglass materials has presented a pressing challenge of resource wastage. To address this dilemma and scrutinize the resource utilization potential of recycled fiberglass, the present study explores the utilization of waste fiberglass materials. Through physical comminution, two distinct forms of recycled fiberglass, namely powder and fibers, were isolated and characterized. The study further investigated the impact of varying dosages of these recycled fiberglass components on the fluidity and resilience of mortar, establishing five distinct dosage tiers. To enhance the compatibility and performance of the recycled glass fibers, four silane coupling agents (KH550/560, KH550/570, KH560/570, KH792/560, KH792/570) were employed for surface modification. At the optimal dosage, a comprehensive analysis was conducted to evaluate the effects of different coupling agents on the mechanical properties of recycled glass fiber-reinforced cementitious materials. The findings revealed that the addition of fiberglass powder significantly enhances the fluidity of the mortar, whereas an increase in fiber content adversely affects its flowability. Notably, the direct incorporation of unmodified recycled glass fibers did not yield significant improvements in the flexural and compressive strengths of the specimens. In light of the substantial variations observed in the flexural and compressive strengths, a maximum addition of 2% recycled glass fibers in reinforced cement mortar products is proposed. The enhanced material performance, particularly with the addition of KH550/570 silane coupling agent, validates the efficacy of incorporating modified recycled glass fibers. This study not only sheds light on the potential utilization of waste fiberglass materials in high-value applications but also paves the way for future research in the area of sustainable resource utilization and waste management.

Porous manganese dioxide powders are synthesized by chemical precipitation from aqueous KMnO₄ solutions in the presence of 1-butanol under mechanical stirring (using a magnetic stirrer) and ultrasonic treatment. The resulting products correspond to δ-MnO₂ in phase composition and exhibit a hierarchically organized supraatomic structure. A comprehensive analysis of the experimental data using scanning electron microscopy (SEM), low-temperature nitrogen adsorption, small-angle X-ray scattering (SAXS), cyclic voltammetry, and galvanostatic charge–discharge methods show that the method of processing the reaction mixture affects the morphology and mesostructure of the resulting δ-MnO₂ powder and does not significantly affect the values of specific capacitance and specific resistance of the electrodes formed based on it. At the same time, we note that according to the modeling data or data obtained by the galvanostatic charge–discharge method, δ-MnO₂, synthesized under ultrasonic treatment conditions, allows obtaining electrodes with specific capacitance values 5% (simulation) or 9% (galvanostatic method) higher and with specific resistance values 11% (simulation) or 58% (galvanostatic method) lower compared to those for electrodes based on δ-MnO₂, synthesized under mechanical processing conditions.

The biocidal action of new protective compounds based on polycrystalline mono-, bis-, and tris-chelate 1,10-phenanthroline acetate complexes of Mn(II) in relation to a wide range of microscopic fungi: Cadophora fastigiata ID-382 and ID-494, Hormodendrum pyri ID-126, Leptosphaeria sclerotioides ID-433, Paraphoma fimeti ID-110a, Penicillium aurantiogriseum ID-408, Thelebolus microspores ID-423, Tricellula aquatica ID-533 isolated from wood of the Arctic regions of Russia is studied. Acetate complexes of Mn(II) with mono-, bis-, and tris-chelate-coordinated 1,10-phenanthroline: Mn(phen)(OAc)₂·2H₂O, Mn(phen)₂(OAc)₂·2H₂O, and [Mn(phen)₃](OAc)₂·5H₂O are synthesized starting from manganese(II) acetate tetrahydrate Mn(OAc)₂·4H₂O and 1,10-phenanthroline monohydrate phen·H₂O by complex formation in melts. The obtained complexes are characterized by IR spectroscopy, ESP, and diffractometry. All three compounds exhibit strong fungistatic and fungicidal activity that is most pronounced for the coordination-saturated tris-chelate [Mn(phen)₃](OAc)₂·2H₂O with maximally hydrophobic cations. The obtained results show the prospects of searching among carboxylate complexes of manganese(II) with coordinated 1,10-phenanthroline for effective environmentally friendly biocides for protecting wood from biodegradation under the conditions of the Arctic regions of Russia.

Synthetic nanotubes of nickel hydrosilicate (pecoraite) are treated with aqueous solutions of cobalt chloride, sulfate, and nitrate at various temperatures and salt concentrations under hydrothermal conditions. It is shown that under hydrothermal conditions, when nanotubes interact with a 0.1 M solution of cobalt nitrate for more than 4 h at a temperature ≥180°С the formation of the cobalt oxide phase Co₃O₄ is observed in the form of crystals of lamellar morphology. This phase actively crystallizes with the concentration of the Co(NO₃)₂ solution increasing up to 0.5 M. At the same time, the nanotubular structure of pecoraite is preserved. In the case of treating nanotubes with solutions of cobalt sulfate and chloride, significant amorphization of the hydrosilicate structure is observed, most likely leading to the complete destruction of the tubular morphology at a temperature of 220°C.

This article presents the results of a study on protective, dielectric, and thermally resistant organosilicate coatings (OSCs) based on a ladder polymer, polyphenylsilsesquioxane (PPSQ), which is used as a film-forming agent. For the first time, a classical approach is employed to calculate the formulations of pigmented coatings in relation to organosilicate compositions (OSComps). The average viscosity molecular weight of the selected film-forming agent PPSQ is determined. The developed coatings exhibit high thermal resistance up to 420°C while maintaining the necessary physicomechanical and electrophysical properties.

This article presents the results of a study of the relationship between the thermal conductivity and mechanical properties of foam glass using complex numerical modeling of thermal processes and the stress–strain state (SSS) of the material. The density of foam glass demonstrates a linear dependence on the formation of residual stresses. It is established that the porosity of foam glass leads to the formation of significant temperature gradients in the area of contact between the foam glass matrix and the gas. The average pore diameter has the greatest impact, while the annealing speed has the least effect. Analysis of the dependence of stress on the temperature and cooling rate shows that the stress in the pores is significantly lower than in the foam glass matrix. The distribution of residual stresses has a parabolic configuration with maxima in the central region. Validation of the numerical simulation by comparing theoretical predictions with the experimental data confirms the correctness of the obtained results.

This article presents the results of the refinement of the crystal structure of α-Cs₂SO₄ at a temperature of 800°C in the edge and apex models. The arrangement of the oxygen atoms’ sites, which are not fixed by symmetry, unlike the Cs and S sites, is clarified. It is proposed that the edge model better corresponds to the experimental data and satisfies the crystallochemical parameters. However, the bond lengths in the apex model are in better agreement with the published data.