Glass and Ceramics最新文献

Zinc magnesium aluminosilicate (ZMAS) glasses were obtained with the addition of Na₂O (from 1.1 to 7.0 mol.%). The influence of the Na₂O content on glass forming ability and effectiveness of the ion-exchange treatment in molten KNO₃ was studied. The dependencies of depth and stress of subsurface layer on treatment duration were also studied along with an evaluation of the concentration shifts of alkaline cations in result of ion-exchange process. It is shown that glass Vickers hardness increases both with the Na₂O content in glass and with the duration of ion-exchange. Vickers hardness of the ion-exchanged glasses with 7 mol.% of Na₂O treated duration for 72 h reaches 900 HV. The possibility of using an ion-exchange process with glass-ceramics obtained from glasses of ZMAS system modified with sodium oxide is discussed.

Based on calculations, the spatial distribution of the local electric field (LEF) for various structural configurations of silver nanoparticles (NPs) in silicate and zinc-phosphate glasses was studied. The features of this distribution determine the efficiency of energy transfer from plasmonic NPs to rare earth (RE) ions located in the particle vicinity. The mechanism of energy transfer through field enhancement via surface plasmon resonance of particles, which is dominant for NPs of sizes of ≥ 5 nm, is determined by several factors. To clarify their roles and significance, the dependencies of LEF upon the size, spatial distribution, and degree of agglomeration of silver NPs in glass were studied. Comparative analysis of the nature of the field enhancement in places of hypothetical location of RE ions was carried out on the basis of a visual representation of the spatial distribution of the LEF in the vicinity of agglomerates of plasmonic NPs. Based on simulations, the dependencies of LEF intensity enhancement, the spatial distribution of such places in relation to the nearest plasmonic particle, upon the concentration of NPs, their size, degree of agglomeration, and the presence of small (≤ 5 nm) particles in the sample along with the relatively large ones, were determined. The optimal configuration of silver particles in glass for obtaining the maximum average enhancement of LEF intensity per the site of possible location of RE ion is revealed to be an agglomerate of NPs with sizes slightly larger than 25 nm and average distances between particle centers about 30 nm.

The structural characteristics of ceramic brick samples with minimum and maximum slag content at the micro-, macro-, and meso-levels were determined using electron microscopy. Mercury intrusion porosimetry revealed the influence of nickel slag on reducing the number of the most critical pores with a size of 0.002 – 0.050 μm (meso-level) of a ceramic body, ensuring regulation of the formation of the pore phase during the firing process and increasing the frost-resistance of products. At the same time, it was established that an increase in the mass content of slag in the composition of the raw material charge, starting from 5%, determines the increase in the volume of pores larger than 0.050 μm (macro level) in the volume of the finished product. This causes a decrease in the strength of the samples. The results of electron microscopy of samples with a minimum and maximum content of nickel slag confirmed the identified structural features of the composite ceramic material at the micro-, macro-, and meso-level and were used in the development of technology for the production of ceramic bricks with the addition of industrial waste of nickel production.

A technology for facing material based on mechanically activated cullet modified with potassium hydroxide was developed. The phase composition, macro- and microstructure of the facing material were studied. It was found that the structure of the composite modified with potassium hydroxide is represented in the interpore space by needle-shaped and columnar crystals of potassium silicates. Physicomechanical characteristics of facing material were investigated.

An energy-efficient synthesis of highly porous ceramic materials based on Sc₂O₃ was conducted using a combination of compaction and technological combustion methods with the participation of active binders. Using XRF (x-ray phase analysis), SEM (scanning electron microscopy), and EDA (energy dispersive analysis) methods, it was found that the investigated material has a morphology based on Sc₂O₃ and thortveitite Sc₂Si₂O₇ that is highly developed, multi-level, and microstructural. The basic characteristics of the material’s pore space (porosity, pore size, specific surface area, permeability, etc.) were determined by means of mercury porosimetry and alternative methods.

The influence of the technological glass-melting parameters of the selected composition in the SrO–Al₂O₃–P₂O₃–SiO₂–F system on the value of the refractive index and the amount of fluorine remaining in the glass structure post-melting was investigated. The lowering of the melting temperature combined with tableting of the charge [batch] increases fluorine absorption in the glass up to 17 wt.% at the same time, and the value of the refractive index reduction to n_D = 1.49. It was experimentally established that in the multicomponent glass selected for glass-ionomer cements with two glass-forming oxides (SiO₂ and P₂O₂) and a high Al₂O₃ content, each wt.% of fluorine reduces the refractive index by about 3.5 × 10 ^–4 units.