Phase Composition and Structure of Aluminum – Coating Composite

Low-melting enamel coatings for household aluminum kitchenware are synthesized. The possibility of formation of low-melting glasses in the system R₂O – Al₂O₃ – B₂O₃ – TiO₂ – P₂O₅ is studied. An optimum glass matrix composition with a decreased firing temperature (580°C) is selected.     

Low-Melting Coatings for Glass Decoration

The optimum titanium-bearing lead-free glass compositions have been developed for producing low-melting white coatings on sheet glass. The properties of glasses and coatings and their structure and phase composition are studied. The optimum conditions for the formation of coatings are determined.     

Mathematical Modeling of the Optimum Conditions for Formation of Enamel Coatings on Aluminum

This paper reports on the results of research in the field of enameling of aluminum cooking utensils with low-melting lead-free enamels based on glasses in the R ₂O–Al₂O₃–B₂O₃–P₂O₅–TiO₂ system. The preliminary optimization of the compositions and properties of enamel coatings made it possible to obtain coatings with a high-quality surface in a minimum number of experiments.     

Phase composition and structure of dull low-melting glazes

The possibility of producing dull low-melting glazes for ceramic products to be fired according to a slow firing regime based on the system Na₂O-MgO-CaO-B₂O₃-Al₂O₃-SiO₂ is demonstrated. The results of studying glaze glasses and coatings by x-ray phase analysis, electron microscopy, infrared microscopy, etc. are described. A correlation between the structure and the phase composition of coatings and their qualitative characteristics is established. The main properties of synthesized dull glazes are specified. __________ Translated from Steklo i Keramika, No. 4, pp. 19–23, April, 2006.     

Interactions between oxides and compounds in the ZrO2-Al2O3-SiO2 system and a glass melt

Conclusions The interaction between ZrO₂, Al₂O₃, ZrSiO₄, and 3Al₂O₃·2SiO₂ with alkali silicate glasses of three compositions has been studied. It is shown that the greatest resistance to the effect of a molten glass is found in ZrO₂ and Al₂O₃. Therefore, the most promising compositions in the ZrO₂-Al₂O₃-SiO₂ system are those which contain baddeleyite and corundum as the crystal phases with the minimum amount of silica.The most aggresive oxide in the composition of the glasses used in this experiment is K₂O whose interaction with the refractory leads to the formation of low-melting compounds.The dissolution of corundum in the glass and the associated change in the properties of the glass have been studied. It is established that the dissolution of Al₂O₃ is the result of its interaction with the melt and the formation of low-melting compounds (alkali aluminosilicates of the feldspar type) while the emergence of a more viscous contact zone in the glass around the corundum grains lowers the rate of dissolution of Al₂O₃.Translated from Ogneupory, No. 2, pp. 50–53, February, 1980.     

The Fluxing Effect of Mineral Material – Cullet Compositions on Enamel Glass

Enamel glasses are synthesized based on the Na₂O – B₂O₃ – Co₂O₃ – SiO₂ system, including perlite, nepheline concentrate, and cullet. The physicochemical and technological properties of the resulting glasses and one-layer coatings based on these glasses are considered. A comparative analysis of the fluxing effect of the nepheline - cullet and perlite-cullet compositions on glasses is carried out. The reference composition areas are shown to be suitable for the development of one-coat powdered glass enamels.     

Fabrication of low-melting glasses in the ZnSO4 -KPO3 - NaPO3 and Li2SO4 - Na2SO4 - K2SO4 - NaPO3 Systems

Low-melting glasses of the ZnSO₄-KPO₃ -NaPO₃ and Li₂SO₄ -Na₂SO₄ K₂SO₄ -NaPO₃ systems are investigated. It is established that me wider me so-called cation assortment, i.e., the greater the number of cations R ⁿ⁺ in the system, the more probable and the easier is the glass formation. It is shown that the occurrence of the processes of structure formation in low-melting glasses depends considerably on the forces of weak intermolecular interaction. For this reason, the investigated glasses have unique properties, namely, are low-melting and have low chemical stability and an anomalously high TCLE (over 300 × 10^–7 K^–1)     

Properties, Structure, and Application of Low-Melting Lead–Bismuth Glasses

Glass formation, crystallization, and physicochemical properties, as well as glass structure in the system PbO – ZnO – Bi₂O₃ – B₂O₃ – SiO₂, are investigated in the section with a constant molar content of glass-formers (B₂O₃ + SiO₂) equal to 20%. A nonlinear dependence of glass properties on their composition is established caused by the change of the coordination state of lead ion in glass structure. The developed glasses are recommended for joint and seals in the production of a new generation of physical parameter sensors.     

A Low-Boron Dielectric Coating for Aluminum

A titanium-boron-silicate system containing alkali metal oxides and lead, strontium, cadmium, chromium, and cobalt oxides is studied for the purpose of developing a low-melting enamel coating for aluminum. The influence of the polyalkali effect and the SiO₂ : TiO₂ ratio on the conductivity and chemical resistance of the glass is studied. The possibility of obtaining a low-melting (firing temperature 540 – 560°C) corrosion-resistant enamel with a high resistivity based on the indicated glass system is demonstrated.     

Tinted Low-Melting Enamels for Aluminum

The possibility of formation of low-melting glasses in the R₂O – RO – Al₂O₃ – B₂O₃ – TiO₂ – P₂O₅ system at a firing temperature of 550°C is investigated. A correlation of glass formation in the considered system with the content of Al₂O₃ and P₂O₅ is established, and the composition of a transition layer with crystalline phases of Na₂O · P₂O₅, Al₂O₃ and Al₂O₃ · P₂O₅ is determined.     

Activation of Sintering of a Ceramics Based on SiC and Its Mechanical Properties

The technological conditions of fabrication, the phase composition, and the mechanical properties of sintered compositions in the SiC – Al₂O₃ – Y₂O₃ system are described. The processes occurring in their sintering are studied.     

Modern Low-Melting Borosilicate Glasses and Glazes for Majolica and Pottery (A Review)

A review of low-melting borosilicate glasses and glazes for majolica and pottery is presented. The data given on the compositions and properties of glasses make it possible to identify a particular composition with the required properties and locate its patent source.     

Synthesis and Properties of Glasses in the NaF–ZnSO4 System

The glass-forming ability is studied in the NaF–ZnSO₄ system. It is revealed that, when melts are cooled at a rate of 10³ K/s, the glass formation is observed in the concentration range 35–70 mol % ZnSO₄. The characteristic temperatures are determined by differential thermal analysis. According to these temperatures, fluorosulfate glasses can be assigned to low-melting glasses. The density of glasses is measured by hydrostatic weighing. The experimental data obtained are used to calculate the molar volume and the thermal stability parameters of fluorosulfate glasses.     

Effects of composition and phase relations on mechanical properties and crystallization of silicate glasses

Crystallization, mechanical properties, and workability are all important for the commercialization and optimization of silicate glass compositions. However, the inter-relations of these properties as a function of glass composition have received little investigation. Soda-lime-silica glasses with Na₂O-MgO-CaO-Al₂O₃-SiO₂ compositions relevant to commercial glass manufacture were experimentally studied and multiple liquidus temperature and viscosity models were used to complement the experimental results. Liquidus temperatures of the fabricated glasses were measured by the temperature gradient technique, and Rietveld refinements were applied to X-Ray powder diffraction (XRD) data for devitrified glasses, enabling quantitative determination of the crystalline and amorphous fractions and the nature of the crystals. Structural properties were investigated by Raman spectroscopy. Acoustic echography, micro-Vicker's indentation, and single-edge-notched bend testing methods were used to measure Young's moduli, hardness, and fracture toughness, respectively. It is shown that it is possible to design lower-melting soda-lime-silica glass compositions without compromising their mechanical and crystallization properties. Unlike Young's modulus, brittleness is highly responsive to the composition in soda-lime-silica glasses, and notably low brittleness values can be obtained in glasses with compositions in the wollastonite primary phase field: an effect that is more pronounced in the silica primary phase field. The measured bulk crystal fractions of the glasses subjected to devitrification at the lowest possible industrial conditioning temperatures indicate that soda-lime-silica glass melts can be conditioned close to their liquidus temperatures within the compositional ranges of the primary phase fields of cristobalite, wollastonite, or their combinations.     

Pyroelectric composites based on LaBSiO5 stillwellite

Synthesis of ferroelectric materials by glass crystallisation is attractive to produce both high-quality textures and composites. In the present work, composites based on ferroelectric stillwellite-like LaBSiO₅ and glasses having compositions near to compounds Pb₅Ge₃O₁₁, PbLiPO₄ and PbBPO₅ were synthesised and their dielectric and pyroelectric properties examined. A pyroelectric coefficient of about 0.5 nC/cm² K may be obtained by liquid-phase sintering of pellets. Preliminary data on crystallisation processes of the lead-containing glasses as well as on the chemical interactions between stillwellite-like LaBSiO₅ and glasses at the sintering temperature are reported.     

Development of microfibers for bone regeneration based on alkali-free bioactive glasses doped with boron oxide

In this paper, we present a new series of alkali-free bioactive glasses (BG) based on FastOs^® composition (38.49 SiO₂ – 36.07 CaO – 19.24 MgO – 5.61 P₂O₅ – 0.59 CaF₂, expressed in mol %), which was modified by partially replacing silicon dioxide network-former with boron trioxide network-former, utilizing calcium oxide as a charge compensator. The main objective of this study was to obtain a new family of bioactive glasses suitable for the fabrication of glass fibers. The BGs were prepared by melt quenching technique and their structural and thermal properties were determined. Glass rods were used to obtain fibers by the classic drawing technique. The bioactivity of the fibers was subsequently assessed through immersion tests in simulated body fluid (SBF) to establish their ability to form hydroxyl carbonated (HCA) apatite onto their surfaces. Glasses with moderate substitution of SiO₂ with B₂O₃ exhibited enhanced thermal properties, allowing to significantly suppress the crystallization trend, and favoring to draw the fibers. The structure of the studied glasses was obtained by NMR spectroscopy. The structure-property correlations were established by their relationship to the configurational entropy. Smaller amounts of substitution resulted in larger entropy of the glasses. Moreover the SBF tests revealed an extensive formation of HCA, comparable to the parent FastOs^®BG composition, which assures fast bonding to the bone. Thus, presented glass fibers may be considered as promising materials for wool-like bone implants or as reinforcing constituent of biopolymer matrix composites.     

Silicon Nitride—Grain Boundary Oxynitride Glass Interfaces: Deductions From Glass Bulk Properties

Oxynitride glasses exist as grain boundary phases in Si₃N₄ ceramics. This paper provides an overview of oxynitride glasses outlining effects of composition on properties. A review of the effects of grain boundary glass chemistry on fracture resistance of silicon nitride is given. A knowledge of overall additive compositions and their quantities in Si₃N₄ combined with measured properties of bulk glasses allows residual stresses in the interfacial glasses to be calculated. Increase in Y:Al ratio leads to higher thermal expansion mismatch and higher residual stresses in intergranular glasses. Values are in good agreement with those obtained using micromechanical finite element analysis.     

Solder Glass Sealing

The development of low-melting solder glasses which make possible the sealing of ordinary glasses at temperatures near their annealing point is described. The properties required of such solder glasses are discussed and some compositions which meet these requirements are given. The high-lead region of the system PbO-B₂O₃-Al₂O₃-SiO₂ is taken up in detail. The effect of the addition of ZnO to this system is also considered. Devitrification is a problem in the use of some of these glasses. The technique of applying the solder glass in various types of seals is described. The advantages and disadvantages of this kind of sealing are pointed out.     

Dependence of the Hydrogen Permeability Coefficient in Glasses of the Sodium-Silicate System on the Silica Modulus

The system Na₂O – SiO₂ used in designing compositions for producing gas microcontainers (microspheres) is investigated. Based on a known equation, an expression is obtained for the dependence of the hydrogen permeability coefficient of glass on its silica modulus. It is established that the alkaline modifier even in the form of an impurity can influence gas permeability. A conclusion is made on the need to apply criterial valuations in designing glasses. A nomogram is obtained for determining the silica modulus, hydrogen permeability coefficient, phase composition, and probability of glass formation in the Na₂O – SiO₂ system.     

Lead-free low-melting-point glass as bonding agent for TiO2 nanoparticles

This work is a study of the properties of TiO₂-anatase nanoparticles attached by a low-melting point inorganic glass (530°C). Unlike other low-melting glasses, this composition does not contain any toxic metal. Likewise, it shows an excellent wettability on ceramic nanoparticles. A small addition of 5 vol% of glass remarkably enhances the mechanical strength of the composites with respect to pure TiO₂ calcined at the same temperature, becoming twice this value. Self-cleaning properties analyzed using the methylene blue 385 nm UV-A photodegradation test showed that, after different UV-light periods, the photo-efficiency of TiO₂-anatase was not altered by the presence of this glass.