Production Of Glass-ceramics Research Articles

Current trends in the use of rare earth metals and their compounds in metallurgy and production of optical materials

It is difficult to name such an area of modern science and technology where rare earth metals (REM) would not be used. Generalization of all existing information on this issue due to its enormous volume and variety is hardly possible and advisable. Therefore, to write literary reviews in this area, one or two relevant segments in a global issue are usually selected and considered in detail. In this review, metallurgy and the production of optical materials are selected as such segments. In metallurgy, first of all, it should be noted the use of rare earth metals in the composition of multicomponent heat-resistant alloys for aviation and space technology, as deoxidizers, for the formation of a perfect structure when creating composite materials and coatings. The use of REM is growing both in ferrous and nonferrous metallurgy. In ferrous metallurgy, increasing the resistance of austenitic steel to oxidation by adding yttrium and cerium, creating composite coatings with additives of yttrium oxide to achieve special properties, etc. In nonferrous metallurgy, composites based on aluminum alloys with additives of cerium oxide; composites based on tin bronze doped with cerium oxides; titanium alloys doped with yttrium, etc. Rare earth metals are an integral part of research on the creation of lasers, solar cells, optoelectronic amplifiers, etc. for use in optoelectronics and other fields of glass materials and ceramics production. These areas of application of rare-earth metals include aluminosilicate glasses, borate glasses, and various types of optical ceramics. A group of new alloyed materials for various laser devices and installations has been created. Such materials include fluortellurite glasses doped with erbium, multicomponent fluoride glasses doped with europium and holmium, tungsten sodium phosphate glasses doped with trivalent REM ions, germanate glass doped with erbium and ytterbium, and others. Research in this area is continuously expanding. The study was supported by a grant from the Russian Science Foundation (project No. 20-13-00180).

Unravelling the effect of nano-heterogeneity on the viscosity of silicate melts: Implications for glass manufacturing and volcanic eruptions

Traditionally depicted as homogeneous materials, manmade and volcanic glasses are often subjected to nanostructuration during demixing and crystallization of their parental melt. While the controlled formation of nanocrystals has been exploited for decades in the industrial production of glass-ceramics to obtain materials with superior properties, nano-heterogeneities have been recently recognized in volcanic products erupted explosively. Here, a multi-pronged approach is adopted to highlight how the emergence of nano-heterogeneities exerts a previously unexplored influence on the viscosity of multicomponent silicate melts. Calorimetry and viscometry provide evidence of how the formation of TiO2- and FeO-bearing nanocrystals increases the effective viscosity of suspensions. Raman spectroscopy and transmission electron microscopy allow the correlation between the increase in viscosity and the degree of sample modification. This study has implications for glass and glass-ceramics manufacturing and for the development of better numerical models of volcanic eruptions, which are key for the operational assessment of volcanic risk.

Characterisation of co-mixed HIP wasteforms for Magnox sludge and clinoptilolite wastes

Co-mixed simulant wasteforms consisting of calcined Magnox sludge simulant and clinoptilolite, with additions of a glass forming frit and CeO2 or U3O8 were processed using Hot Isostatic Pressing (HIP). This enabled the production of high waste loaded materials, with the successful incorporation of both simulant and active material. These formed heterogeneous glass-ceramic products, with decomposition of raw materials and some vitreous phase formation. The aqueous durability of these materials was assessed over a 28-day period using a modified PCT test, and favourably compared to the durability of an international glass. Overall this verifies the potential for HIP technology to be used in wasteform production, with potential large reductions in waste volume, especially if co-mixed wastes are considered.

Crystallization Behavior and Optical Properties of Glass-Ceramics Containing Nano-Diopside Crystals

Diopside is a ceramic material with excellent properties including a low dielectric constant, high thermal conductivity, low sintering temperature below 1000 °C, and high mechanical strength. It has been applied to wireless and optical communications, substrates for touch panels, lenses for UV-LED, building materials, and so on. In this study, glass-ceramics containing nano-sized diopside crystals were fabricated, and their transmittance at visible light and photoluminescence were evaluated. In particular, TiO2 was added as a nucleating agent to suppress the surface crystallization phenomenon and Mn was used as a dopant to emit red light. The glass-ceramics were prepared by heat treatment at a temperature lower than the maximum crystal growth temperature (TP) calculated from the non-isothermal analysis method using differential thermal analysis (DTA) for the formation of nano-sized crystals. For glass containing 20 wt% of TiO2, the Avrami constant was calculated to be 2.23 and the activation energy required for crystal growth to be 549 kJ/mol, reflecting typical bulk crystallization behavior. Glass-ceramics with high light transmittance up to 70% were obtained by inducing the bulk crystallization behavior, and the diopside crystal size was less than 10 nm, which was equal to or higher than that of commercialized transparent glass-ceramic products. Glass-ceramic specimens doped with Mn showed luminescence of 736∼766 nm wavelength at excitation light of 365 nm wavelength. The emission peak intensity increased with the amount of dopant added, but gradually decreased with increasing crystallinity of the diopside phase.

Технология обработки ситалла на примере травления и очистки моноблока кольцевого лазера

The paper uses production of the main part of a ring laser, that is a monolithic sitall crystal, as an example to describe the main stages of manufacturing and chemical processing of the SO-115M lithium aluminosilicate sitall glass-ceramic material. We analysed composition optimisation and glass-ceramic production methods and investigated the effects of various components (such as glass formers, modifiers, and clarifiers) on the optical performance of the finished article. We describe the sequence of main monolithic crystal processing operations: etching and cleaning, which includes degreasing, ultrasonic treatment, rinsing and drying. We tested an original etchant formulation and present an etching rate calculation for it. We selected a solution for ultrasonic cleaning of the article and assessed the resulting surface finish quality

Application of modified red mud in environmentally-benign applications: A review paper

Red mud (RM) is a waste product that results from bauxite refining via the Bayer process. Its disposal remains an issue which raises significant environmental concerns, particularly if disposed on land or water bodies. Much research has been done on the use of red mud for environmentally-benign applications such as wastewater treatment, catalysis, the production of construction materials and glass ceramics, and for the recovery of metals. This paper reviews the current efforts made in the utilization of red mud as a valuable industrial by-product, which in turn should minimize its harmful impact on the environment. This detailed review compiles and highlights a variety of novel applications of modified red mud as a coagulant, an adsorbent for wastewater treatment, as well as, its use in catalytic processes and in building materials. The physico-chemical properties of red mud can be tuned by a range of treatment methods include acidification, neutralization and heat treatment. As revealed from the literature reviewed, modifications on red mud for the removal of various types of contaminants have shown promising results. However, further amendment and modifications on red mud are needed to utilize this industrial waste in many other industrial applications.

Sinter-crystallization of spodumene LAS glass-ceramic tiles processed by single-firing

For the manufacturing of glass-ceramic products, a monolithic glass is prepared using the same technologies for the conventional glass production, followed by a thermal-treatment of nucleation and crystal growth. An alternative process could be the production of glass-ceramic materials by pressing of glass powders and densification by sintering. In this way, the same equipment used in a traditional ceramic tile plant could be used to produce components with complex geometry. In this work, the single-firing process was used to obtain LAS glass-ceramic (Li2O.Al2O3.SiO2) tiles. The aim of the work was to determine the effect of particle size, pressing and sintering temperature on the bending strength and thermal expansion coefficient of the glass-ceramic tiles. The raw materials were melted in alumina crucibles (1480 °C, 80 min) and the obtained glass was quenched in water and annealed (600 °C). The glass was milled for 1 and 2 h (ball mill), resulting in two particle sizes, 9.1 μm (1 h) and 22 μm (2 h). The powders were granulated and pressed at 35 and 45 MPa, resulting in four processing conditions. In sequence, the compacts were dried (150 °C, 24 h) and sintered at 1175 and 1185 °C (10 °C/min heating rate). The microstructure of the glass-ceramic tiles was determined by SEM and XRD techniques. The bending strength was determined by the 3-point method and the thermal expansion coefficient (CTE) was determined by dilatometry. As a result, LAS glass-ceramics tiles were obtained, showing high modulus of flexural strength (70–80 MPa) and very low thermal expansion coefficients (1.2–1.4 × 10−6 °C−1). Surface crystallization was achieved and the main phase was β-spodumene. Sintering was simultaneous to crystallization, in a typical one-step process.

An energy-efficient two-stage hybrid flow shop scheduling problem in a glass production

Energy-efficient scheduling is highly necessary for energy-intensive industries, such as glass, mould or chemical production. Inspired by a real-world glass-ceramics production process, this paper investigates a bi-criteria energy-efficient two-stage hybrid flow shop scheduling problem, in which parallel machines with eligibility are at stage 1 and a batch machine is at stage 2. The performance measures considered are makespan and total energy consumption. Time-of-use (TOU) electricity prices and different states of machines (working, idle and turnoff) are integrated. To tackle this problem, a mixed integer programming (MIP) is formulated, based on which an augmented ε-constraint (AUGMECON) method is adopted to obtain the exact Pareto front. A problem-tailored constructive heuristic method with local search strategy, a bi-objective tabu search algorithm and a bi-objective ant colony optimisation algorithm are developed to deal with medium- and large-scale problems. Extensive computational experiments are conducted, and a real-world case is solved. The results show effectiveness of the proposed methods, in particular the bi-objective tabu search.

Use of Bypass Cement Dust from Al-Kufa Cement Factory for Production of Glass Ceramic Material

Bypass cement dust was supplied from Alkufa cement factory, which has been used in preparing glass ceramic material. The percentage of bypass cement dust which is included in the overall batch is about 30 wt%. The bypass cement dust composition has been modified by adding other materials like marble, granite, and silica, to prepare glass ceramic material by powder technology. The prepared samples with different ratios ingredients were pressed under a load of 15 tons/cm2 for 90 sec, in a steel mold of 30 mm in diameter, liquid phase sintering is carried out by using High-Temperature Furnace at 100 – 1250 º C and 208/ 240 VAC. Techniques including SEM (Scanning electron microscopy) and XRD (X-ray diffraction) tests were then used to evaluate the produced material. The obtained glass ceramic material have high bulk and apparent density, low apparent porosity , high compression strength and hardness , low electrical and thermal conductivity. The XRD and SEM results showed that glass ceramic materials are formed. The phase transformation has happened and the titanite, wollastonite, diopside, periclase, and silica condense clusters phase are formed, which are the important phases of glass ceramic. Tests show that the sample A5 contains 38% bypass cement dust, 30%granite, and 32% silica , the sample C5 contains 28% bypass, granite 30%, marble 10%, and silica 32% and the sample B4 contains 59% bypass , 25% marble, and 16% silica . Showing properties A5 and C5 which conform to that of glass ceramic properties better than B4. The research is considered a pioneer work in the field of investment of dust of bypass cement for producing glass ceramic materials. It represents an important step and could be the basis for future researches leading to the achievement of glass ceramic production in Iraq.

Energy efficient production of glass-ceramics using photovoltaic (P/V) glass and lignite fly ash

This study investigates an innovative approach for the valorization of specific wastes generated from the energy sector and the production of glass-ceramics. The wastes used were photovoltaic (P/V) glass, produced from the renewable energy sector, and lignite fly ash, produced from the conventional energy sector. The process first involved the production of glass after melting specific mixtures of wastes, namely (i) 70% P/V glass and 30% lignite fly ash, and (ii) 80% P/V glass and 20% lignite fly ash, at 1200 °C for 1 h as revealed by the use of a heating microscope. The results indicated that the P/V glass, as a sodium-potassium-rich inorganic waste, reduces energy requirements of the melting process. The produced glass was then used for the production of glass-ceramics. Dense and homogeneous glass-ceramics, exhibiting high chemical stability and no toxicity, were produced after controlled thermal treatment of glass at 800 °C. The mechanical (compressive strength, Vickers hardness) and physical (open porosity, bulk density and water absorption) properties of the produced glass-ceramics were evaluated. X-ray diffraction (XRD) and Energy Dispersive X-ray fluorescence (ED-XRF) were used for the characterization of the raw materials and the produced glass-ceramics. Scanning electron microscopy (SEM) provided further insights on the microstructure of the final products. The properties of the produced glass-ceramics, namely water absorption and compressive strength, render them suitable for applications in the construction industry. The waste valorization approach followed in this study is in line with the principles of circular economy.

Influence of Sintering Temperature on Mechanical Properties of Glass-Ceramics Produced with Windshield Waste

In this work, glass-ceramics were produced with mechanical and physical properties, using recycled glass powder from windshields as raw material. The glass powder was formed and sintered at temperatures 600, 650, 700, 750, and 800°C. Pieces were also produced with the addition of niobium oxide to the glass powder. The flexural strength and the Archimedes density of the produced parts were determined. The reliability of the results was evaluated by the Weibull statistic. X-ray diffraction was performed. Maximum flexural strength was 77.64 MPa at 750°C, with the addition of niobium oxide at 43.86 MPa at 700°C. X-ray diffraction showed crystalline structures in the specimens with the addition of the nucleating agent, confirming the production of glass-ceramics in this composition. The pure glass powder only crystallized from 750°C. The Nb2O5 favors the formation of crystalline structures in the vitreous matrix at low temperatures and with piezoelectric structures.

Preparation and Properties of Blast Furnace Slag Glass Ceramics Containing Cr2O3

AbstractIn this study, the blast furnace slag of the Baotou Steel and Iron Company was used as the main raw material to prepare glass ceramics with diopside as the main crystal phase. The composition of the parent glass was designed by thermodynamic calculations with FactSage software. Small amounts of the nucleation agent Cr2O3were then added to the parent glass to induce crystallization. Differential thermal analysis was used to determine the nucleation and crystallization temperatures of the glasses, and scanning electron microscopy and X-ray diffraction were adopted to determine the microstructures and phase compositions of the glasses after heat treatment, respectively. The results showed that glass ceramics of the diopside phase can be prepared with up to 73 wt% blast furnace slag when 1.44–1.91 wt% Cr2O3is added, and the ceramics have uniform compact grains and a high bending strength of about 84.6–101.7 MPa. In addition, the mechanical properties are better than those of natural marble and granite. These results provide basic information and a scientific basis for industrial production of diopside glass ceramics using molten blast furnace slag as the main raw material.

The Formation of a Comfortable Habitat and the Economic Feasibility of Using Alternative Thermal Insulation Technologies

The pace of construction and renovation of buildings is increasing every year. This encourages the search and introduction of new materials and technologies to improve the comfort of housing. An important problem is also the need to ensure the energy efficiency of buildings. A peculiarity of the Russian natural conditions is a significant daily and annual difference in atmospheric temperatures. The use of various thermal insulation materials in the construction process will significantly reduce the cost of maintaining buildings and provide comfortable conditions for people, regardless of natural events. In addition, the use of certain facade treatments solves the aesthetic problem and can protect against precipitation and industrial emissions. Therefore, the purpose of this study is to find additional possibilities for thermal insulation of buildings using non-traditional technologies and materials. Modern approaches to the aesthetics of buildings involve the use of expensive mineral thermal insulation materials. Reducing the cost of their manufacture is possible through the use of industrial waste. Wastes from non-ferrous metallurgy are suitable for the production of slag wool or for the production of slag glass-ceramics. A wide range of possibilities allows the use of various wastes in the manufacture of bricks to increase porosity, strength and frost resistance. The use of a number of additives also provides an increase in economic efficiency and environmental friendliness of production. The use of special coatings for gypsum finishing materials could increase their strength and water resistance. The quality of facade paints is significantly increased when using aluminum silicate liquid sodium glass. Fine-dispersed waste of metallurgical enterprises will allow to lower the cost of production of liquid glass and aluminosilicate glue. The use, obtained from waste, astringent, provides for the production of heat-insulating materials the production of bright colors without the use of pigments. High strength and water resistance of materials can ensure the use of magnesian waste. Keywords: thermal insulation, energy efficiency, industrial waste, building materials, finishing materials, paints.

Synthetic wollastonitic glass ceramics derived from recycled glass and medical waste incinerator fly ash

The present investigation focuses on the production of synthetic wollastonitic glass ceramics (WGCs) through vitrification of medical wastes incinerator fly ash (MFA) with soda lime recycled glass (SLRG) at 1300 °C, followed by re-crystallization in the range of 950 °C. The sintering process was carried out at the final temperature, previously determined by differential thermal analysis (DTA). The raw materials as well as the produced WGCs were characterized by chemical mineralogical and microstructural analyses. Their leaching behaviour was evaluated using the EN 12457-2 compliance leaching test. Re-crystallization led to the development of glass ceramics with two major crystalline phases: monoclinic wollastonite (b-CaSiO3) and gehlenite (Ca2Al2SiO7). The compressive and bending strength values varied from 190 to 194 MPa and 79–82 MPa, respectively. Although MFA exhibited high metals leaching values, indicating a hazardous waste, no trace elements were detected in the leachates of the WGCs.

The Effect of Lithium on Crystallization and Microstructure of Glass-Ceramics in Soda-Lime Silicate System

This study investigated the crystallization of soda-lime silicate (NCS) system by re-melting soda-lime silicate glass cullet with Al2O3 CaCO3 and Li2O. The Li2O was added as a nucleating agent. The effect of the nucleating agent on crystallization was investigated in order to study the possibility for use as a parent glass for glass-ceramics. Soda-lime silicate cullet was the main raw material and its chemical composition by weight was 68% SiO2 2% Al2O3 9% Na2O 9% K2O 3.5% CaO 2.5% MgO 1.2% TiO2 3% SrO and 2% ZnO. Glass batches with composition (%wt) of (65-x) Cullet:13Al2O3:22CaCO3:x(Li2O) (x = 0, 1, 2, 4, 6 and 8) were melted at 1500°C for 3 hours and annealed at 600°C. All glasses added with Li2O were clear except x = 8. The crystallization was investigated by Differential Scanning Colorimetry technique (DSC). The results exhibited the exothermic peak of crystallization (TpI and TpII). The glasses with added Li2O exhibited decreasing crystallization temperature with increasing Li content. The glasses were heated at temperatures around the crystallization temperature (700, 750 and 800°C). After heat treatment, the crystalline phase in the glasses was determined by X-ray diffraction technique (XRD). The microstructure was investigated by optical microscope and Scanning Electron Microscope (SEM). The phases of Nepheline (Na,K)AlSiO4 and Wollastonite (CaSiO3) were found. The crystallization depended on the heat treatment temperature. The thermal expansion of the glasses was determined by the dilatometric method to indicate the characteristics of the glass-ceramics. In conclusion, Li2O had a strong effect on the crystallization in soda-lime silicate system. The result could be applied for the production of glass-ceramics from soda-lime cullet.

MODERN PRODUCTION AND TREATMENT TECHNOLOGIES USING THERMAL PLASMA ENERGY

The paper presents research results on silicate melt and glass-ceramic material production based on ashes generated by thermal power plants using the energy of thermal plasma. A plasma-chemical reactor is designed and tested. Calculations show that when the thermal power of plasma torch varies from 50 to 100 kW and the optimum melt temperature of 1850 °C is maintained in the plasma-chemical reactor, the feed rate varies. The dependence between the crystallization properties of the melt and the mixture composition is established. To obtain the material with increased crystallinity, the resulting silicate melt is subjected to plasma treatment at 700 °C for 1 hour and 950 °C for 2 hours. The degree of crystallinity increases up to 60–65 %. Compressive and flexure strength and coefficient of linear expansion of obtained products are determined. The obtained results are compared with those available in the domestic and foreign markets.

The application of «lean production» capabilities for improvement of the glass-ceramics production by small batches. Part 3. The analysis results and the ways to reduce the defect level

The examples are given for the «lean production» capabilities application (such as Pareto diagram, cause and effect diagram of Ishikawa and others) to the analysis of the problems appearing at the science-absorbing industries in the process of the small batches glass-ceramics wares manufacturing. The reasons for the defects occurrence were established, the influence of the supplementary stages on the amount and nature of the detected defects was demonstrated. Some ways how to remove the identified problems are proposed and backed up with facts.

Crystallization kinetics of machinable glass ceramics produced from volcanic basalt rock

This study investigates the utilization of basalt in manufacturing machinable glass ceramics. As the fluorine and potassium phases, MgF2 and K2O added into basalt are responsible for the machinability of glass ceramics. Three different compositions containing 80%, 85%, and 90% basalt, with K2O and MgF2 as the remainder, were mixed and melted in an alumina crucible at 1500 °C. Glass samples were obtained by casting the melt into a graphite mould. Glass ceramics were prepared through subsequent crystallization heat treatment of the obtained glass. Compositional and mechanical characterizations were carried out via XRD-SEM and hardness/fracture toughness and machinability tests respectively. The effect of change in the obtained phases with basalt composition on the machinability of glass ceramics was investigated. Furthermore, crystallization kinetics of the glasses were investigated by differential thermal analysis (DTA) using the Kissinger kinetic model with several different heating rates. This study reports that basalt can be utilized in the production of machinable glass ceramics only if the basalt ratio is justified. The results showed that good machining performance was observed in low-basalt content conditions (B80), When the basalt content increased (B85 and B90), the machining capability decreased markedly. Furthermore, the crystallization activation energies decreased with increase in basalt content.

Crystallization pathways in glass-ceramics by sintering cathode ray tube (CRT) glass with kaolin-based precursors

The crystallization mechanisms for the formation of glass-ceramics by sintering CRT glass with kaolin-based precursors were investigated by quantitatively determining the crystalline and amorphous phases in the products. Amorphization of sintered products was observed in CRT/kaolinite and CRT/mullite glass-ceramics systems at 700–900 °C. With the increase of temperature, the crystallochemical formation of lead feldspar and orthoclase was detected. Orthoclase was found to be the major crystalline phase in both CRT/kaolinite and CRT/mullite systems at 1000–1100 °C. When the temperature increased to 1000–1100 °C, lead feldspar was formed as the only crystalline phase to host Pb. The leaching tests suggested that the glass-ceramic product sintered by CRT/kaolin-based precursors has stronger resistance against acid attack because of the incorporation of lead into lead feldspar crystal protected by glass matrix. The incorporation of CRT glass into glass-ceramics provides a promising strategy for reducing the environmental hazard of CRT glass.

PHYSICOCHEMICAL AND THERMOPHYSICAL PROPERTIES OF GLASS-CERAMIC MATERIALS DEPENDING ON THEIR COMPOSITION

The paper deals with rock glass-ceramic materials in CaO-MgO-FeO-Al2O3-SiO2system and studies their thermal and thermal diffusivity, viscosity, thermal expansion coefficients, crystallization temperature range. The suggested thermodynamic and kinetic dependences are used in trying out the temperature-time parameters of glass-ceramic material production. Industrial and local natural waste are used to design 19 glass-ceramic compositions which underwent semicommercial testing.