Investigation of the structure glass-ceramic materials according to data of IR spectroscopy

The efficiency of the use of IR spectroscopy in studying the structure of magnesium-aluminosilicate glass-ceramic materials was analyzed. It was established that the formation of the structure of these glass-ceramic materials during the heat treatment is associated with a distortion of the cordierite structure. The presence of solid solutions, high and low cordierite in the structure of the materials under study was detected according to the systems of bands F2, E2, C2 and D2, depending on the temperature of their heat treatment. The mechanism of phase formation in magnesium-aluminosilicate glass-ceramic materials has been determined, which consists in the formation of future crystals of -cordierite and spinel at the initial stages of nucleation, and crystals of -cordierite and mullite at the stage of crystallization. Formation of a finely dispersed glass-ceramic structure with a predominant content of -cordierite or mullite under conditions of low-temperature heat treatment is a decisive factor in ensuring high thermal and mechanical properties of glass-ceramic materials. This allows them to be used as structural elements of devices and equipment under thermal and mechanical loads.

Cutting inserts made of glass and glass ceramics

Against the background of the increasing cost and scarcity of raw materials that are required for the manufacture of cutting tools, the question of alternative cutting materials arises. Glasses and glass ceramics represent a possibility for this, the use of which has hardly been considered so far. This thesis is devoted to the question of whether cutting tools can be made from glass and glass ceramic materials at all. In addition, the question of how such tools can be used for which purposes is dealt with. First results on both questions are presented. The grinding of indexable inserts from the materials examined was possible without breaking corners and edges. Plastics can be easily machined with the tools produced. When machining aluminum, however, the tools made of glass fail completely, while those made of glass–ceramic show good results here too. These first results are intended to pave the way for further research in this area.

Light Scattering in Glass Ceramic X-ray Imaging Plates

<p>Glass ceramic materials have been suggested as a possible high resolution replacement for current commercial storage phosphor imaging plates. The low spatial frequency of the current plates is caused by strong scattering of the laser light incident on the plate during the read-out process. Glass ceramic materials show very small scattering due to their transparent nature, which should lead to a higher resolution. However, a competing argument is the small amount of scattering that does occur travels a much greater distance in the plate, limiting the resolution. The aim of this thesis was to simulate the scattering of light in imaging plates and use this to optimise the trade-off between resolution, sensitivity and transparency which is implicit in plate design. Additionally, experiments were performed to determine the resolution of glass ceramic and commercial imaging plates. Simulations show that high resolution can be achieved in both the strong and weak scattering limits, corresponding to opaque and transparent materials. Increasing the absorption of the laser light increases the resolution, as does decreasing the laser beam diameter and power. An increase in the resolution almost always comes at a cost of a decrease in the sensitivity. The resolutions of an Agfa MD30 and glass ceramic imaging plate were found to be 4:5 line pairs/mm and 6:5 - 8:0 line pairs/mm respectively for an MTF equal to 0:2.</p>

Light Scattering in Glass Ceramic X-ray Imaging Plates

<p>Glass ceramic materials have been suggested as a possible high resolution replacement for current commercial storage phosphor imaging plates. The low spatial frequency of the current plates is caused by strong scattering of the laser light incident on the plate during the read-out process. Glass ceramic materials show very small scattering due to their transparent nature, which should lead to a higher resolution. However, a competing argument is the small amount of scattering that does occur travels a much greater distance in the plate, limiting the resolution. The aim of this thesis was to simulate the scattering of light in imaging plates and use this to optimise the trade-off between resolution, sensitivity and transparency which is implicit in plate design. Additionally, experiments were performed to determine the resolution of glass ceramic and commercial imaging plates. Simulations show that high resolution can be achieved in both the strong and weak scattering limits, corresponding to opaque and transparent materials. Increasing the absorption of the laser light increases the resolution, as does decreasing the laser beam diameter and power. An increase in the resolution almost always comes at a cost of a decrease in the sensitivity. The resolutions of an Agfa MD30 and glass ceramic imaging plate were found to be 4:5 line pairs/mm and 6:5 - 8:0 line pairs/mm respectively for an MTF equal to 0:2.</p>

Glass formation and properties of glasses in the system SrO–B2O3–SiO2–xAl2O3 (x=0; 10 mol.%)

The paper shows the prospects of the system SrO–Al2O3–B2O3–SiO2 as a basis for the synthesis of new vitreous and glass-ceramic materials, which are widely used as electrical insulated and high-temperature coatings, for sealing of solid oxide fuel cells, and in the production of heat resistant materials. We experimentally established the conditions of glass formation, regions of glass-forming melts and properties of glasses, the chemical composition of which is limited by the following content of components (mol.%): SrO 30–80, B2O3 10–60, SiO2 10–60, and Al2O3 0–10. It is shown that during the synthesis of glasses in the corundum crucible at the temperature of 13500С the region of glass formation in the system SrO–B2O3–SiO2 is limited by the following content of components (mol.%): SrO 30–60, B2O3 10–60, and SiO2 10–50. It is found that the introduction of Al2O3 to the composition of these glasses expands the region of glass formation towards increase of the SiO2 content in the glass up to 60 mol.%. Experimentally determined values of glass properties are within the following limits: coefficient of linear thermal expansion (67–118)10–7 К–1; glass transition temperature 570–6600С; dilatometric softening point 580–7000С; and density 2.62–3.71 g cm–3. The established patterns of influence of the components and conditions of glass formation on the physical and chemical characteristics of glasses may serve as an experimental basis for designing of new materials with a complex of specified properties, which allows solving the problems of their practical use.

Effect of Phosphorus on Crystallization of Alkaline Molybdenum-Containing Borosilicate Glasses

The effect of additives of P2O5 on the solubility of molybdenum in the amorphous part of glass and on the phase composition of the crystallized part of the highly alkaline glasses of the Li2O–(Na2O–K2O)–B2O3-SiO2 system was studied. The comparison of the phase composition of samples with or without phosphorus prior and after annealing allowed to determine the change of solubility of molybdenum in the amorphous part of the samples and to evaluate the thermal stability of the synthesized glass-ceramic materials. It was found, that for the compositions without phosphorus and the samples without lithium, when molybdenum is added at the synthesis stage, almost all of the molybdenum is included only in the crystalline molybdates. The study has shown an increase in the solubility of molybdenum only in the structure of lithium-containing glasses with phosphorus.

Application of Statistical Methods in Predicting the Properties of Glass-Ceramic Materials Obtained from Inorganic Solid Waste

This paper uses mathematical methods as the basic tool at the stage of experiment planning. The importance of research programming applications was shown using the theory of experiments and the STATISTICA software. The method of experiment planning used in the case of studying the properties of a mixture, depending on its composition, features considerable complexity. The aim of the statistical analysis was to determine the influence of variable chemical composition of waste materials on selected properties of glass-ceramic materials. A statistical approach to multicomponent systems, such as ceramic sets, enables the selection of appropriate amounts of raw materials through the application of ‘a plan for mixtures’. To utilize the raw waste materials, e.g., slags from a solid waste incinerator, fly or bottom ashes, in the modeling of new materials, a mathematical relationship was developed, which enables estimating, based on the waste chemical composition, selected technological and practical properties of the glass so as to obtain a material featuring the required technological–practical parameters. For the obtained glasses, a comparative analysis of the experimentally and computationally determined properties was carried out: transformation temperature, liquidus temperature, density, and thermal expansion coefficient. The obtained high theoretical approximation (at the level of determination correlation coefficient R2 > 0.8) confirms the suitability of the polynomial model for mixtures for applications in the design of new glass-ceramic products.