Production Of Glass-ceramics Research Articles

Investigation of Li2O and TiO2 effects on MAS glass-ceramic produced from waste material

Among glass-ceramics, MgO-Al2O3-SiO2 (MAS) system occupies an important place due to its good characteristics. In this study, the magnesite waste being an industrial waste was evaluated for the production of MAS glass ceramics and the properties of the glass-ceramics produced were examined. For this purpose, mixtures were prepared using magnesite waste, quartz, kaolin and alumina raw materials according to the chemical composition of cordierite. Furthermore, in the mixtures prepared with the additions of TiO2 and Li2O added as a nucleating agent the effects of these additions on the crystallization temperatures were investigated. Crystallization temperatures of the glass samples were determined by the differential thermal analysis (DTA) and characterized by X-ray analysis (XRD). Subsequently, the glass-ceramic transformation was performed at 1000, 1050, 1100, 1150, and 1200?C for 1, 3, 5 and 10 hours. The products obtained were analyzed using X-ray (XRD) and scanning electron microscope (SEM). In addition, the microhardness of glass-ceramic products and their corrosion resistance in an acidic environment were measured and compared in this study.

Life cycle assessment for the production of MSWI fly-ash based porous glass-ceramics: Scenarios based on the contribution of silica sources, methane aided, and energy recoveries

Municipal solid waste (MSW) production in the world has increased by 60 % in recent years. Incineration of MSW reduces their volume in conjunction with energy recovery. Incineration produces two residues, namely bottom ash (BA) and fly ash (FA), with high concentration of heavy metals and organic pollutants, especially for FA, making them an environmental concern. Vitrification is a costly, highly safe high temperature treatment, ensuring encapsulation of heavy metals. FA vitrification requires a source of silica to be able to get vitrified. In this study, we have proposed valorizing treated (vitrified) FA through the production of porous glass-ceramics, subsequently to MSWI. The entire process, from incineration to glass-ceramics production, was evaluated for several scenarios by Life Cycle Assessment (LCA) using Sima Pro 9.0. Three main scenarios were analysed; each one considering a different silica source: bottom ash (BA), glass cullet (G) and silica sand (S), and for each scenario, three thermal recovery subscenarios were assumed: no thermal recovery used to heat FA prior to vitrification (N), heating FA prior to vitrification using incineration gases thermal recovery (T) and methane-combustion-aided thermal recovery, which exploits methane combustion to further increase the gases temperature (M). Results proved that vitrification was a technically feasible and environmentally-energetically sustainable technology. The result indicates that the most eco-sustainable scenario was using bottom ashes as a silica source together with methane-combustion-aided recovery: 0.467 kgCO2,eq, 5.83 × 10-8 carcinogenic-CTUh and 9.26 MJ required per kg of glass-ceramics produced.

Glass-ceramics synthesis using the collaborative smelting slag of spent automotive catalyst and copper-bearing electroplating sludge

This paper studied the glass-ceramics preparation from the collaborative smelting slag of spent automotive catalyst (SAC) and copper-bearing electroplating sludge (CBES) by the one-step sintering method without additional nucleating agents. The crystallization mechanism, including nucleation and crystal growth steps, was investigated by DSC, XRD and FETEM-EDS. The crystallization process during heat treatment could be summarized as follows: Fe3+ ions will congregate firstly in a small range on the surface and inside of the originally homogeneous amorphous matrix, and then gradually crystallize and transform into stable hematite (Fe2O3) crystal nuclei. Augite and gehlenite as the main two crystalline phases grow around hematite (Fe2O3) epitaxially. Additionally, the surface crystallization dominates the overall process based on the crystallization kinetics calculation. The optimum sintering temperatures of glass-ceramics preparation were researched according to the physicochemical properties analysis. When the sintering temperatures are 850℃−875℃, the density, water absorption, Vickers hardness, flexible strength, acid and alkali resistance of glass-ceramics products are 2.8–2.9 g/cm3, 0.08%–0.09%, 6.5–6.7 GPa, 98–115 MPa, 96.6%–96.9% and 98.5%–99.6%, respectively. Toxicity characteristic leaching procedure (TCLP) test shows that the material can be taken as non-hazardous. This work realizes resource utilization and detoxification of the co-smelting slag of SAC and CBES.

Effect of TiO2 on crystallization and mechanical properties of MgO–Al2O3–SiO2 glasses containing P2O5

MgO–Al2O3–SiO2 glass-ceramics have been widely used in military, industrial, and construction applications. The nucleating agent is one of the most important factors in the production of glass-ceramics as it can control the crystallization temperature or the grain size. In this study, we investigated the effect of replacing P2O5 with different amounts of TiO2 on the crystallization, structure, and mechanical properties of an MgO–Al2O3–SiO2 system. The crystallization and microstructure were investigated by differential scanning calorimetry, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The mechanical properties were investigated by measuring the Vickers hardness, Young's modulus, and fracture toughness. The results showed that adding TiO2 favored the precipitation of fine grains and significantly increased the Vickers hardness, Young's modulus, and fracture toughness of the glasses. Introducing an appropriate amount of TiO2 can make a glass structure more compact, promote crystallization, and improve the mechanical properties of MgO–Al2O3–SiO2 glass-ceramics.

Crystallization characteristics, microstructural evolution, and Cr migration mechanism of glass-ceramics synthesized entirely from low-carbon ferrochromium slag and waste glass

The disposal and large-scale reutilization of industrial solid waste in construction materials have been gaining considerable interest. Herein, the synthesis of glass-ceramics from low-carbon ferrochromium slag (FCS) and waste glass is reported. The crystallization characteristics, microstructural evolution, and Cr migration mechanisms of the glass-ceramics were investigated through offline quenching experiments. The physical properties and Cr ion leaching performance were tested and evaluated. As the low-carbon FCS content was increased, glass network depolymerization was promoted and the crystallization ability was effectively improved. When 50 wt% low-carbon FCS was added, the compressive strength and Vickers hardness of the glass-ceramics reached maximum values of 160.26 MPa and 736 Hv, respectively. Simultaneously, the dominant crystalline phase in glass-ceramics was transformed from diopside and wollastonite into gehlenite when the low-carbon FCS content was further increased to 60 wt%, thereby reducing the mechanical properties. Cr2O3 primarily existed as a [CrO6] octahedron and Cr-containing spinel in the parent glass, resulting in composition segregation. On combining the growth orientation of diopside and spinel, the resulting specific crystal coating structure improved the Cr ion leaching performance. Considering the physical properties and risk of Cr leaching, the optimal FCS content in glass-ceramics is 40–50 wt%. These findings indicate that the production of glass-ceramics from low-carbon FCS and waste glass is an effective and environment-friendly method for co-utilizing these two solid wastes.

Investigation into the viability of the properties of porous glass-ceramics produced from granite dust and maize cob for use in thermal insulation of external walls of residential buildings

Given the enormous need for cost-effective wall insulation materials in the developing countries and Nigeria specifically, this study, explores the viability of porous glass-ceramics production from granite dust and maize cob using one-step sintering technology. The chemical compositions of the locally sourced materials used including granite dust, ball clay and maize cob were obtained using XRF. 300µm of granite dust and ball clay as well as 425µm of maize cob powder were used. Different amount of granite dust and maize cob powder were mixed with constant amount of a mixture of NaOH and Na2SiO3 in three different groupings to formulate the porous glass-ceramics samples. The formulated samples were uniaxially pressed at 10MPa and sintered in a gas kiln at 850oC for 3 hours. The sintered samples were subjected to experimental tests. The results showed water absorption, apparent porosity, bulk density, compressive strength and thermal conductivity of 25.6%–46.7%, 43.5%–75%, 1.45g/cm3 –1.9g/cm3, 0.7MPa–9.7MPa and 0.11W/m.K–0.53W/m.K respectively. The mineralogical properties of the sintered samples were obtained using XRD. The results indicated a viable material for use in thermal insulation of residential buildings.

Ultrafast Nanocrystallization of BaF2 in Oxyfluoride Glasses with Crystal-like Nanostructures: Implications for Upconversion Fiber Devices

Transparent glass–ceramic fibers containing fluoride nanocrystals are attracting attention as upconversion devices. In this paper, a material design is proposed that eliminates the need for heat treatment processes. The impact of short- to medium-range structures on the crystallization of glasses was investigated to enable nanocrystallization in the quenching process via ultrafast nucleation. In this study, the short- to medium-range structures of (33.3 – x/3)BaF2–xZnO–(66.7 – 2x/3)B2O3 glasses were investigated by 11B- and 19F-magic-angle spinning nuclear magnetic resonance spectroscopy, molecular dynamics simulations, and the high-energy synchrotron X-ray diffraction. After heat treatment, glasses with x > 40 formed BaF2 nanocrystals with a diameter of ∼5 nm and a small particle size distribution (<1 nm). Based on the high-energy synchrotron X-ray diffraction, the critical size of the nuclei was estimated to be 4 nm, which was similar to the size of the precipitated crystals. Obvious selectivity in the binding was observed: F– preferred Ba2+ and O2– preferred B3+, whereas Zn2+ was bound to both anions. The binding selectivity caused a bicontinuous structure of oxide and fluoride domains, and the fluoride-related structure factors and bond distance were very similar to the peak positions of the precipitated crystals. Er3+-doped glasses with x > 40 showed upconversion luminescence with a spectrum similar to that of BaF2. These results suggested the pre-existence of a crystal-like structure with a composition, density, and ordering similar to those of the precipitated crystals. Moreover, glass with the modified composition was successfully crystallized during press-quenching of the melt and the fiber drawing process. These results could facilitate the production of photonic components such as nanocrystallized glass fibers and microspheres for upconversion lasers as well as a wide variety of glass–ceramic products.

Utilization of silt, sludge, and industrial waste residues in building materials: A review.

To promote the effective utilization of sludge and slag produced in nature and from human activities, this paper summarizes the research progress in the field of building materials on the basis of expounding their classification and characteristics. (1) Sludge and slag include silt, sludge and industrial waste residues. These three materials are mainly composed of SiO2, which can be used to produce building materials after treatment and can also be used as admixtures, including roadbed admixtures. (2) Silt and sludge are widely used in building wall materials and roadbed materials, etc. Industrial waste residues can be used in the production and processing of green concrete and glass-ceramics. (3) In addition to continuing to use existing utilization methods, key treatment technologies and new treatment devices can be further developed according to the characteristics of sludge and slag. Moreover, observations and mechanistic analysis of the microscopic structure of industrial waste residues and research on strong and weak utilization methods based on the performance of building materials can be carried out, and more efficient and energy-saving excitation or activation technologies will be developed. These efforts will eventually lead to the development of functional building materials with excellent performance and environmentally friendly characteristics to achieve the differentiated utilization of silt, sludge, and industrial waste residues and realize the efficient transformation of resources. This paper provides useful insights for the application of sludge and slag in the field of building materials.

A Review of Porous Glass-Ceramic Production Process, Properties and Applications

Porous materials exist around our environment and play an important role in our daily lives to be used widely in many fields, among the fields are energy distribution and storage, vibration suppression, liquid filtration, heat insulation, and sound absorption. Porous glasses are materials that have pores structure using silica as the primary component in all types of standard and specialty glass mixture with a foaming agent and other additives. Porous glass is usually in the size of nanometre and micrometer range. Porous glass is usually prepared by using phase separation, sintering and sol-gel method [1]. This review paper will focus on the various properties of this porous material related to the production process used to their properties and possible applications such as filtering, lightweight concrete, heat resistance insulator, and biomaterials.

Waste-to-Reuse Foam Glasses Produced from Soda-Lime-Silicate Glass, Cathode Ray Tube Glass, and Aluminium Dross

Aluminium dross is a hazardous industrial waste generated during aluminium production. It contains metallic oxides of aluminium and magnesium, other phases (aluminum nitride), and residues of fluxes and salts from the melting process of aluminium. Discarding this by-product is considered an environmental and economic challenge due to the high reactivity of dross with water or even air humidity. After removing the hazardous components from the as-received dross, one of the optional approaches is to incorporate the treated dross into construction materials. Dross is applied in several types of research as a secondary raw material source for alumina, clinker, cement or glass-ceramic production, but only a few papers focus on the usage of dross as a foaming agent for foams. Even fewer research are reported where dross was applied as a basic component of foam glasses. In this work, foam glasses were produced completely from waste materials: Aluminium dross, container (SLS) glass, and cathode ray tube (CRT) glass. The research holds several specificities, i.e., combining two industrial waste materials (CRT glass and dross), and adding an increased amount from the wastes. The physical and mechanical characteristics were examined with a special focus on the effect of the foam glass components on the microstructure, density, thermal conductivity, and compressive strength.

DETERMINATION OF THE COMPRESSION STRENGTH RP OF MULTILAYER PLATES MADE OF SLAGOSITALS

The methodology of creating multifunctional acoustic automated devices has been further developed, it is based on the construction of simple algorithms for transforming and processing signals of measuring instruments. A differential acoustic method for controlling the physical and mechanical parameters of multilayer plates made of slag glass-ceramics has been investigated. A structural diagram of an automated device for measuring acoustic control of the ultimate compressive strength Rр of a controlled slag glass-ceramics plate is proposed. The option of automation of the measurement process considered in the article makes it possible to carry out measuring control of the strength characteristics for a relatively short period of time and by averaging the results of measurements of the physical and mechanical parameters of slag glass-ceramic plates, leads to a decrease in the values of random measurement errors and thereby contributes to an increase in the accuracy of measurements of physical and mechanical parameters of slag glass-ceramics products. The values of the relative increments of the attenuation coefficient ∆ƞ23/ƞ4were obtained, while the ranges of the values of the attenuation coefficient of a transmission of various waveforms of the piezoelectric transducer correspond to the ranges of the compressive strength Rр of the test sample. At the same time, the control of the strength of the material Rр at multiple frequencies is due to the fact that even a slight change in the geometric parameters of the slag glass-ceramics slab leads to a change in the generalized parameters of the universal transformation functions of the measuring differential acoustic devices, which are associated with the physical and mechanical characteristics of the controlled material of the sample The proposed two-parameter differential acoustic control method allows to keep in mind the linkage between temperature and mechanical parameters: the unequal distribution of the temperature along the length of the sample and the uneven distribution deformation of temperature with the localization of this plastic component in the middle part of the slag glass-ceramics plate, which is most significantly affected by temperature and, as a consequence, is subject to gradual destruction.

Effect of Different Concentrations of Titanium Oxide (TiO2) Addition on the Crystallization Behaviour and Some Properties of Alkaline Earth Aluminosilicate Glass-Ceramics

Glass-ceramics in the CaO-MgO-Al2O3-SiO2 quaternary base glass system was produced via melting technique using feldspar, limestone and magnesite as sources of starting materials. Glass-ceramics production involves making a base glass, annealing and cooling to room temperature and then reheating the base glass to nucleation and crystal growth temperatures. Characterization of the produced glass-ceramics was carried out using a scanning electron microscope (SEM). The effects of the crystallization process on some properties such as hardness, chemical durability in acid and alkali media of samples were determined. The results portrayed that glass-ceramic samples to which various amounts of TiO2 (2,4,6,8 and 10 wt.%) were incorporated showed the formation of crystalline phases dispersed in the matrix of their respective residual glassy phases. Significant improvement in hardness, as well as minimum weight loss, were recorded for all the glass-ceramic samples. On the contrary, the glass samples did not crystallize despite subjecting them to heat treatment, their hardness values were low and they were not resistant to acid (1M HCl) and alkali (1M NaOH) attacks. The inability of TiO2 addition to fully transform them into glass-ceramics remains a shortcoming. However, the glass-ceramic samples obtained from this study can be used for tiling works.

Preparation of high-quality glass-ceramics entirely derived from fly ash of municipal solid waste incineration and coal enhanced with pressure pretreatment

The disposal and high-volume reutilization of municipal solid waste incineration fly ash into environmentally friendly construction materials have been gaining significant interest over the years. This study proposed a new method to produce glass-ceramics with enhanced mechanical properties and chemical leaching characteristics from fly ash and coal fly ash with mechanical pressure pretreatment. A series of co-sintering experiments were conducted by varying proportions of fly ash and coal fly ash, the pretreatment mechanical pressures and sintering temperatures, and the effectiveness was measured by analyzing the thermal behavior, compressive strength, leaching behavior of heavy metals, mineralogical and microstructural characteristics of sintered samples. The results showed that the obtained glass-ceramics exhibited distinguished physicochemical properties, a maximum compressive strength of 51.00 ± 0.86 MPa was obtained. The leaching concentrations of five heavy metals in sintered samples were much lower than the standard limitation. The morphology results showed the coal fly ash addition positively enhanced the stabilization of heavy metals and the formation of new mineral phases. And the compressive strength was evidently improved with the increase of pretreatment pressure, which was attributed to the microstructure transition and increased crystalline degree. These findings suggested that the production of glass-ceramics entirely from fly ash and coal fly ash with pressure pretreatment is a promising method by minimizing the energy consumption together with the co-disposal of two solid waste streams.

Development of CaO-rich blast furnace slag containing fluorine mica-based glass ceramic coatings

In the present study, Blast Furnace Slag (BFS) waste was evaluated as a sustainable, cost-effective CaO, SiO2, Al2O3 and MgO substitute for inorganic oxides for the production of frit, a raw material for glass ceramic production. Two different frits were prepared to compare a commercially available frit (F-STD) with frit produced using BFS waste (F-BFS). The samples were characterized by XRF, XRD, heating microscopy, dilatometry and TG-DTA to determine the chemical composition, phase formation and thermal properties. The frits were applied on steel using the electrostatic spray method and subsequently thermally treated at 830 °C for 4.5 min. The reference (GC-STD) and partially BFS-substituted glass ceramic (GC-BFS) coatings were examined by XRD, SEM-EDS and ICP-MS experiments. The main crystal phase for both samples was Ni-substituted fluorine mica (KLiNi2Si4O10F2). GC-BFS was slightly more amorphous (70%) than GC-STD (69.1%), which was correlated with the thermal properties of the BFS waste. Likewise, ICP-MS analysis after a boiling citric acid test (ISO 28706-1: 2008) revealed that the GC-BFS had relatively higher chemical resistance. The total release from the reference sample (GC-STD) was 23.556 mg/L, whereas the total release from the sustainably produced sample (GC-BFS) was 21.451 mg/L, which was consistent with the XRD results.

Influence of single-side ion exchange parameters in LZS and LZSA sintered glass-ceramics

During processing and use of glass and glass-ceramic products, defects are generated, compromising their mechanical strength and one of the methods applied to promote an increase in mechanical strength is the ion exchange. An ion (usually an alkaline with larger ionic radius) from an external source (usually a salt) replaces position with another alkaline ion (with smaller ionic radius) from material. This ion substitution produces residual compressive stress on materials surface, which can promotes an increasing in mechanical strength. In this context, sintered glass-ceramic from the systems Li2O–Zr2O–SiO2 (LZS) and Li2O–Zr2O–SiO2–Al2O3 (LZSA) were subjected to ion exchange by salt paste method using different sodium-lithium ratios, at temperatures 100°C below to the glass transition temperatures of the parent glasses, with 60–600min holding time. Despite the small amount of sodium obtained after ion exchange (0.30–0.80wt.%), the exchange layer verified in sintered LZS glass-ceramics (up to 900μm) resulted in adequate superficial tensions with 14% mechanical strength increase. Otherwise, the sodium content presented in sintered LZSA glass-ceramics after ion exchange (0.40–0.70wt.%) was distributed in an excessive exchange layer (up to 2000μm) which resulted in decrease of 42% on mechanical strength. For both glass-ceramics systems studied, an increase of Weibull modulus was verified.

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.

Vitrifikacija kao metoda remedijacije zemljišta

Various types of contaminated soil and hazardous waste that have a negative impact on the environment and human health can be treated with the vitrification process. This process is based on thermal treatment of contaminated soil or waste at high temperatures, with the addition of additives, whereby the soil/waste melts and a stable glass is formed. The resulting glass and glass-ceramic products have good mechanical resistance, chemically are resistant and immobilize contaminants, thus preventing their further negative impact on the environment. This paper presents a literature review of the vitrification process of different types of contaminated soil and hazardous waste.

New glass-ceramic from ternary–quaternary mixtures based on Colombian industrial wastes: Blast furnace slag, cupper slag, fly ash and glass cullet

The aim of this research was to evaluate the production of glass ceramics from novel combinations of fly ash, glass cullet, blast furnace slag and copper slag solid wastes. The CaO/SiO2 molar ratios of the mixtures were 0.17–0.39. Glass ceramics were produced by thermal treatment of frits obtained by quenching in water. The results show that samples with a high Fe2O3 content (>4wt%) are not adequate for glass-ceramic formation, as a result of the effect of ferric iron, Fe3+, which increases the network connectivity, on the stability of the glass. The mechanical properties of the ceramic materials were as follows: elastic modulus of 97.8–106GPa, Vickers microhardness of 612–701MPa, fracture toughness of 0.45–0.84MPam1/2, and friction coefficient of 0.57–1.0. For the glass ceramics, the mass loss did not exceed 1% in NaOH and 15% in HNO3 as a result of the crystalline phases formed. The ceramic materials developed in this research could be considered for potential applications in the production of glazes for residential or industrial tiles and coatings, among others.

Crystallization Kinetics and Structure Refinement of CaTiO3 Glass-Ceramics Produced by Melt-Quenching Technique

Glass-ceramic materials were obtained by heat treatment (960 ºC for 2, 4, and 6 hs) of glasses with CaCO3 47.50 wt%-TiO2 23.75 wt%-SiO2 23.75-Al2O3 5.00 wt% formulation produced by the melt-quenching technique (melting at 1650 ºC and subsequent annealing at 650 ºC). The materials’ structural characterization and crystallization kinetics (Kissinger method) indicate the presence of CaTiO3, CaSiO3, and CaTiSiO5 crystalline phases with activation energies 217, 281, and 446 kJ/mol, respectively. The structure refinement (Rietveld method) suggests metastability for the CaSiO3 and CaTiSiO5 phases as a function of the heat treatment time. The increase in time favors CaTiO3 crystallization, from 62.97 wt%, in the 2 hs treated sample, to 79.21 wt%, in the 6 hs treated sample. EDS and microstructure analyses confirm the glass-ceramic production and indicate segregation of the CaTiO3 phase for longer heat treatment times.

Effect of glass content on sintering kinetics, microstructure and mechanical properties of glass-ceramics from coal fly ash and waste glass

In this paper, coal fly ash and waste glass were used as raw materials to prepare CaO–Al2O3–SiO2 system glass-ceramics by direct sintering. The effects of glass content on the kinetics, phase, microstructure and mechanical properties of glass-ceramics were studied by means of liquid phase sintering formula, X-ray diffraction, scanning electron microscope and the corresponding property tests. The results showed that as glass content increased, the activation energy of glass-ceramics first decreased and then increased due to the precipitation of tridymite and augite, and the surface of glass-ceramics gradually became smooth and dense. The water absorption and total porosity of the glass-ceramics were decreased with increase of glass content，while the flexural strength and bulk density were increased. When the amount of waste glass added is 40% and the sintering temperature is 1100 °C, the glass-ceramics have dense surface and high bending strength, which is suitable for high-strength building glass-ceramics. The experimental results of this paper provide a basis for direct sintering industrial production of glass-ceramics.