-
Details
-
Hits: 300
The processes of thermal consolidation of nanoporous glass surface by means of carbon dioxide laser radiation have been investigated. Successful formation of a heat-sealed layer with a thickness of (20 ± 1) ?m was demonstrated under the following heat-sealing regime: average radiation power 10,5 W, defocusing ?f = 16 mm F-Theta lens with a focal length of 157 mm, scanning speed 40 mm/s, track spacing 100 ?m. It is shown that femtosecond pulses can be used to record birefringent structures through a thermally compacted layer, the magnitude of their phase shift being an indirect indicator of glass porosity.
-
Details
-
Hits: 208
The paper shows micro-impurities and defects occurring in glass welded by two-stage method from natural quartz mined in the Urals. It is established that the quality of glass depends on the presence and distribution of mineral and gas-fluid inclusions in natural quartz, as well as on the fractional composition of the grains used and the conditions under which the welding process is carried out. It is noted that almost all trace elements in quartz, pass into the welded glass, thus, the trace element composition of the initial quartz is a critical factor determining its suitability for the production of high-quality transparent quartz glass.
-
Details
-
Hits: 207
The results of investigation of properties (solubility, antiscaling, anticorrosive, algicidal, bactericidal) of glassy copper-zinc-containing phosphate composition (Cu–Zn–FC), which is obtained by waste-free ecological technology for the purpose of corrective treatment of make-up water in centralized heating systems, are presented. The synergetic effect of the joint presence of long-chain phosphates, alternating copper and zinc cations in the composition is revealed, which strengthens, evenly distributes the protective film on the surface of the system elements and provides maximum efficiency in the fight against salt deposits, corrosion, biofouling.
-
Details
-
Hits: 218
The processes of obtaining selective vanadium-containing layers on the outer surface of tubular ceramic membranes based on a-Al2O3 for use in the petrochemical industry have been studied. A layer of V2O5?1.6H2O deposited on the outer surface of the ceramic membrane was obtained by the sol-gel method. The temperature of the heat treatment varied from 400 to 700 C. The chemical stability in a liquid medium of membranes with a deposited layer subjected to heat treatment at 650 C has been studied. It was found that the chemical stability of membranes with a V2O5 deposited layer is in the pH range from 5 to 8. The optimal heat treatment temperature for obtaining a layer with high adhesion to the substrate was 650 C.
-
Details
-
Hits: 262
This work examines the main regularities in the formation of cement stone structure and the relationship between the properties of concrete mixes with various fillers and highly compressed materials obtained through the hyperpressing method. The objective of the study is to develop an efficient technology for producing construction materials using local, including non-standard raw materials and industrial waste, which is important both from an environmental and economic perspective. The experiment investigates the use of semi-dry pressing and hyperpressing to form concrete mixes with improved performance characteristics. It is assumed that during the pressing process, especially under hyperpressing conditions (pressures above 40 MPa), intensive interaction occurs between particles forming macroparticles, which contributes to a stronger cement stone structure. The involvement of Van der Waals forces and valence bonds between filler particles and hydrated clinker minerals, as well as molecular interactions, is considered the key mechanism for enhancing the strength and durability of the material. An important aspect is the use of low-plasticity clays, overburden rocks, and industrial waste, which significantly reduces production costs and improves environmental sustainability. The study also emphasizes that the hyperpressing technology helps reduce the technological cycle time, lowers specific energy consumption, and improves economic efficiency, making this technology promising for the production of environmentally friendly construction materials. The work contributes to the development of new methods for using secondary and local materials in construction, opening up new opportunities for improving the efficiency and sustainability of construction materials production.
-
Details
-
Hits: 166
The glass-forming region in the ternary system TeO2–ZnO–MoO3 was investigated at two melt cooling rates. The achieved molybdenum trioxide content in the glass reached up to 80 mol. % with varying TeO? and ZnO ratios. The phase composition of the batch and the resulting glass under thermal treatment was studied using X-ray diffraction analysis. Within the temperature range of 20…300 °C, no significant interaction was observed between the initial binary oxides. However, upon further heating, complex oxide phases of tellurium (IV), zinc, and molybdenum (VI) (Te?MoO?, Zn?Te?O?, ZnMoO?, and ZnTeMoO?) were formed. The formation of these compounds was also observed during the induced crystallization of the glasses. Transmission spectra of the glass samples were recorded, revealing a redshift of the short-wavelength transmission edge with increasing molybdenum trioxide content.
-
Details
-
Hits: 195
The paper studies the effect of adding potassium form of silicon-phosphorus-antimony cationite (K:KFS-cationite) to a potassium nitrate salt bath on the magnitude of compressive stresses on the surface of sodium-calcium-magnesium silicate glass. Compressive stresses are formed as a result of low-temperature ion exchange Na+ (glass) – K+ (salt melt). Two types of potassium nitrate were studied: technical grade B and chemically pure grade Extra pure. To determine the distribution of compressive stresses in the surface layer of glass, the waveguide spectroscopy method was used, with the help of which the profile of birefringence was measured and the stress profile was calculated. To measure microhardness, a PMT-3 microhardness tester was used. It is shown that the introduction of K:KFS cationite into the potassium nitrate melt leads to an improvement in the ion exchange conditions for two grades of nitrate compared to the salt melt without the cationite – namely to an increase in the value of compressive stresses, the depth of the ion exchange layer and microhardness. The increase in compressive stresses in relation to the initial glass after ion exchange with the addition of cationite was 155 MPa for grade B and 450 MPa – for grade Extra pure. The increase in microhardness in relation to the initial glass was 120 % for grade B and 240 % – for grade Extra pure. The cationite significantly improves the ion exchange conditions for technical potassium nitrate grade B. The introduction of cationite into the salt bath melt is a promising direction in ion exchange technology used to increase the mechanical and thermal strength of glass products. This technological approach is especially relevant in glass strengthening production, where cheaper technical potassium nitrate is used.
-
Details
-
Hits: 187
Synthesis and properties data of the ceramic material based on 31.0BaO–30.0B2O3–15.0Al2O3–7.0SiO2–6.8MgO–5.9ZnO–4.3MgF2 (mol. %) glass and Al2O3 as a filler are provided. Sintered at 875 °C composite ceramics with an initial glass/Al2O3 mass ratio of 60:40 and has ?r = 8.7 and tan ? = 6.6 ·10–4, at frequency 1 MHz. The flexural strength of such ceramics is 117.5 MPa, CTE = 69.7 10–7 K–1, the composite is chemically compatible with silver and can be promising material for the low-temperature of co-fired ceramics technology.
-
Details
-
Hits: 306
In this work, the local atomic structure of neodymium ions embedded in alumoborate glass (5 mol. % Nd2O3) is studied in comparison with the structure of neodymium ions in zinc phosphate glass (0.5 mol.% Nd2O3) using the Fourier analysis of the extended X-ray absorption fine structure (EXAFS) spectra near L3-edge of Nd. The EXAFS spectra of the neodymium oxide recorded at the K- and L3-edges of Nd were considered as an experimental standards. The usage of two absorption edges allowed to determine the spectral characteristics of multielectron excitations contributions to the spectrum and to increase the accuracy of the determined parameters of the local atomic structure. We found that the neodymium atom in alumuborate glass is surrounded, in average, by ~9.6 oxygen atoms at a distance of ~2.4 ?, and in zinc phosphate glass – by ~6.8 oxygen atoms at a distance of ~2.3 ?.
-
Details
-
Hits: 151
The article describes the study of the effect of the tempering mode on the mechanical strength of products. It shows the effect of the press settings and the temperature in the tunnel furnace chambers on the nature of glass failure during testing. It is proposed to use a logistic regression model to predict the nature of failure during mechanical strength testing of manufactured glasses and promptly correct the tempering mode.
