Production Of Glass-ceramics Research Articles

Impact of MgO-ZnO substitution on nucleation of aluminosilicate glasses

The nucleation mechanisms is of technically interest and important in glass-ceramics production. Here we investigate the nucleation behaviors of NiO-doped MgO-Al2O3-SiO2 and ZnO-Al2O3-SiO2 glasses. It is found that crystallization tends to takes place on the surface and the interior of glasses for the former and the latter, respectively. The origin of different nucleation behavior is studied by comparing aluminum coordination, configurational entropy and rheological properties of the glasses. The substitution of MgO by ZnO leads to increase of tetrahedral aluminum concentration, and decrease of configurational entropy above glass transition temperature, in particular, the latter is closely related to volume nucleation. In addition, the qualitative comparison of thermodynamic and kinetic barriers of steady-state nucleation rate of two glasses indicates that ZnO-bearing aluminosilicate glass possesses higher diffusivity and lower critical nucleus size, which favoring volume nucleation.

Production of glass-ceramics from fluorinated sludge: Structure, properties and leaching risk

Fluorinated sludge (FS) is a solid waste with massive discharge. To mitigate environmental pollution and optimize resource utilization, FS was employed in the fabrication of glass-ceramics. The impacts of different FS additions (40–60 wt%) and sintering temperatures (1000–1150°C) on the crystalline phase, microstructure, properties and leaching performance of glass-ceramics were discussed. Crystallization kinetics were studied to analyze the crystallization mechanism of glass-ceramics. The results showed that the predominant crystalline phases of glass-ceramics were anorthite and fluorite. The increasing sintering temperature facilitated the growth of crystals and the polymerization of glass network, resulting in improved densification. When the FS addition was 50%, sample sintered at 1100°C with a flexural strength of 47 MPa exhibited the best comprehensive performance: a density of 2.29 g/cm3, Vickers hardness of 584 HV. FS addition has resulted in an increase in the activation energy of glass-ceramic. The main pattern of crystallization was volume crystallization in glass-ceramic. The F− leaching concentration of all glass-ceramics is lower than 1 mg/L, which will not cause environmental pollution. Only when the FS addition was above 55%, there was a leaching risk for Cu and Zn in the sample due to its poor acid resistance. It is a promising way for FS to manufacture glass ceramics as a high-value construction material.

Phase evolution of Nd3+-doped natural garnet minerals systems: A potential host phase for trivalent actinide immobilization

The immobilization of long-lived actinides produced from spent fuel reprocessing poses a significant environmental concern. In this work, we synthesized glass-ceramics at low temperatures using natural garnet minerals as precursors to immobilize trivalent actinides. Two primary metrics, the quantitative distribution of Nd3+ in glass-ceramics and its leaching rate, were employed to explore the mechanism of Nd3+ immobilization in glass-ceramic products. XRD results show that the primary crystalline phase of the glass-ceramics transitions from calcium feldspar and spinel to oxyapatite with increasing Nd2O3 content. Within a specific range, the proportion of Ca2Nd8(SiO4)6O2 in the samples increases from 37.9 % to 57.9 % with rising Nd2O3 content, while the glassy phase proportion decreases. The distribution of Nd3+ in Ca2Nd8(SiO4)6O2-based glass-ceramics was quantitatively investigated using a combination of TEM-EDX and Rietveld refinement calculations. Nearly 70 % of Nd was found to benefit from a double sealing barrier (Oxyapatite + glass) even under high Nd2O3 loading. A 42-day leaching experiment was conducted using deionized water as the medium. The data demonstrated that Ca2Nd8(SiO4)6O2-based glass-ceramics exhibited a lower Nd-normalized leaching rate(LRNd∼10−5 g m−2 d−1) in solution compared to products solely relying on the glass network for actinide immobilization. This work introduces a cost-effective natural solution for trivalent actinide immobilization.

BATCH COMPOSITION INFLUENCE ON SINTERING AND CRYSTALLIZATION PROCESSES OF CORDIERITE GLASSES OBTAINED BY THERMAL PLASMA MELTING

This article focuses on the production of glasses and glass-ceramic materials with a cordierite (2MgO∙2Al2O3∙5SiO2) composition. The processes of crystallization and sintering of cordierite glasses, which are based on natural raw materials, pure oxides and pre-synthesized cordierite, have been investigated. It has been determined that cordierite glasses produced via plasma melting exhibit high structural defects attributed to rapid heating and cooling rates. The relaxation of microstresses in the glasses takes place within the temperature range of 480 – 490 °C. Glasses based on synthesized cordierite exhibit a crystallization temperature of 930 – 1020 °C, depending on the presence and type of nucleating agents. This is approximately 20 – 50 °C lower compared to glasses based on component mixtures. The primary crystallization product of studied glasses at 900 °C is the high-quartz solid solution with formula MgO∙Al2O3∙3SiO2, which is dissociate above 1000 °C with the formation of cordierite. The addition of 5% ZrO2 to the batch increases the viscosity of softened glasses and their crystallization temperature, resulting in increased activity of glass powders in the sintering processes due to the higher impact of liquid-phase sintering on the general densification process of glass-ceramics. This allows for the production of glass-ceramics with open porosity of 2 – 4% at 1300 – 1350 °C. The addition of 5% TiO2 to the batch reduces the glass crystallization temperature. However it does not significantly effect on the cordierite glass-ceramics sintering processes. For citation: Sharafeev S.M., Shekhovtsov V.V., Zvyagina E.E. Batch composition influence on sintering and crystallization processes of cordierite glasses obtained by thermal plasma melting. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 7. P. 80-87. DOI: 10.6060/ivkkt.20246707.7032.

Experiments Using Different Types of Waste to Manufacture Ceramic Materials: Examples on a Laboratory Scale

Reusing waste as raw materials to produce other materials can entail a decrease in production costs and in the abusive use of natural resources. Furthermore, it can even improve the properties of the end product or material. In this sense, a review of the most relevant literature published in recent decades shows that numerous solutions have been proposed or implemented, such as its use to produce construction materials, catalysts, pigments, pozzolana, refractory materials, glass-ceramic products, etc. Our research group has verified the viability of using different types of waste as secondary raw materials to obtain several types of ceramic, glassy and glassceramic materials, as well as frits. This article highlights several types of industrial waste that have both non-toxic (Li, Ca and Mn) and highly toxic (Cr VI) differentiating elements that can be used in sintering and vitrification industrial processes to immobilise them or render them inert. We studied the compositions and characterised the various materials obtained, conducting toxicity and leaching tests on waste/materials designed with high amounts of chromium. A suggestion for future lines of research has been proposed.

Enhancing fluorescence properties in transparent glass ceramics via optimized Gd2O3/Ga2O3 ratios and crystallization conditions

In this study, Gd2O3–Ga2O3-GeO2-Nd2O3 glasses and glass ceramics were synthesized, and their structural, thermal, and crystallization characteristics were analyzed. Our findings indicate that substituting Gd2O3 for Ga2O3 positively influences the enhancement of bridge oxygen content and network structure stability. Heat treatments at different temperatures showed no significant impact on the crystal phase type but did alter the crystallization rate. Optimal conditions were identified: a Gd2O3/Ga2O3 ratio of 0.6 facilitated the production of transparent glass ceramics containing a single-phase GdGaGe2O7 nano-crystal. Notably, the glass ceramic nucleated at 780 °C for 24 h and crystallized at 840 °C for 5 min exhibited superior performance. Despite a 6% reduction in transmission rate, the emission intensity at 1060 nm increased by 1.5 times. This material holds promise for various applications in solid-state lasers operating within the 1.06 μm region.

Study on the Production of Glass-Ceramics from Diabase Rocks: A case study of Uzbekistan

Study on the Production of Glass-Ceramics from Diabase Rocks: A case study of Uzbekistan

Innovative pathways to high-performance glass ceramics: Harnessing nature's treasures with chromium and zirconium nucleation catalysts

This study explores the novel production of high-performance glass ceramics (GCs) by harnessing readily available and cost-effective raw materials schist, dolomite, and magnesite for the first time. The nominal composition for the base glass, G(30), was designed based on the eutectic composition of the diopside-anorthite ratio with 30% enstatite content within the quaternary CaO-MgO-Al2O3-SiO2 system. To enhance nucleation, chromium (Cr2O3) and zirconium (ZrO2) oxide were separately introduced into the base glass batch in two ratios (0.5% and 1%), producing four additional batches-Cr(0.5), Cr(1), Zr(0.5), and Zr(1), orderly. All these batches were melted at temperatures ranging from 1450 °C to 1550 °C then cast into glass discs and rods. Double-stage heat treatment schedule, 750 °C /2 h followed by 950 °C and 1050 °C/1 h separately, was employed to induce the transformation of prepared glass into GCs. X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques were applied to orderly investigate the developed crystalline phases and the prevailing micro-structures of the prepared GCs. The glass ceramic with the highest Cr2O3 ratio, Cy(1) which was treated at 1050 °C/1 h, displayed the most adequate microstructure and minimal pore formation in comparison with other GCs. As well, the favorable physicochemical properties, Vickers microhardness (6.43 GPa), low thermal expansion coefficient (0.171 ×10 −6 °C−1) at 29–100 °C, and the exceptional resistance for acid and alkali corrosion (95%), nominate such GS sample, Cy(1), for several architectural applications.

Recycling of waste glass and incinerated sewage sludge ash in glass-ceramics

Disposal of waste glass and incinerated sewage sludge ash (ISSA) in landfills is a waste of resources and poses significant environmental risks. This work aims to recycle waste glass and ISSA together to form value-added glass-ceramics. The physical and mechanical properties, leaching behaviour, and microstructure of the glass-ceramics produced with different proportions of waste glass powder (WGP) and ISSA were investigated. Thermodynamic calculations were performed to predict the formation of crystalline phases and the phase transformation involved. The results showed the potential of WGP and ISSA as raw materials in glass-ceramics production. WGP effectively densified the microstructure of the glass-ceramics by forming a viscous phase. As WGP content increased, the total porosity of glass-ceramics decreased whereas the density increased, accompanied by the formed anorthite transforming into wollastonite. The incorporation of WGP densified and refined the pore structure of the glass-ceramics, thereby improving the mechanical properties and reducing the water absorption. The glass-ceramics produced with a 50:50 blend of WGP and ISSA exhibited the highest compressive strength of 43.7 MPa and the lowest water absorption of 0.3 %. All fabricated glass-ceramics exhibited innocuous heavy metal leaching. The co-sintering of ISSA and WGP can produce additive-free glass-ceramics, characterized by reduced energy consumption and notable heavy metal immobilization capacity. These materials hold promise for utilization in construction as building materials.

Wollastonite-containing glass-ceramics from the CaO–Al2O3–SiO2 and CaO–MgO–SiO2 ternary systems

Glass-ceramics (GCs) are polycrystalline materials produced from parent glasses by the controlled crystallization that results in crystalline phase(s) embedded in a residual amorphous matrix. Typically, GCs are produced by a conventional glass route with subsequent crystallization for which two heat treatments are usually applied, the former to generate nuclei and the latter being a crystal growth stage. Alternatively, another technically viable route for manufacturing GCs involves sintering of glass-powder compacts followed by crystallization (sinter-crystallization).Wollastonite-containing GCs from the CaO–Al2O3–SiO2 and CaO–MgO–SiO2 systems find a wide variety of uses in different technological fields, including construction, architecture, medical and high-tech fields. For example, a special type of wollastonite-containing GC marketed under the name of Neoparies®, which is stronger and lighter than natural stone, features high resistance to weathering/chemical attack and is manufactured on a large scale for construction and architectural applications. In the biomedical field, the well-known Cerabone® products have been used in bone-contact applications for many years.The main goal of this brief review is to provide a critical analysis of the experimental trials focusing on the synthesis of wollastonite-containing GC materials and to discuss the various fields of their application. Constitution of phase diagram of CaO–Al2O3–SiO2 and CaO–MgO–SiO2 systems are comprehensively discussed with connection to melt crystallization path and crystalline phase formation. Furthermore, special emphasis will be given to the production of wollastonite-containing GCs for construction and architectural purposes from natural raw materials and wastes, as well as to the recent advancement in developing wollastonite-containing GC biomaterials for bone repair.

Surface integrity and material removal mechanisms of Zerodur glass-ceramics by Gallium infiltration in high-pressure polishing

The core of the production of ultra-precision optical glass-ceramics are the reduction of high-stress concentration and micro-crack growth during polishing. This work aimed to study the effect of gallium solidification in the interfacial micro-structure on the micro-crack growth and the effect of the mechanical properties of glass-ceramics with gallium under different polishing stresses. In this study, a new polishing method was introduced. This innovative technique involves the infiltration of liquid gallium as a filler into the sub-surface of the workpiece. The gallium subsequently solidifies within the micro-cracks of the workpiece, effectively offset surface defects and improving the polishing outcome. The results of the gallium infiltration polishing method show that glass-ceramics workpieces with defects are repaired by solidified gallium, allowing them to be polished at higher pressures, reducing polishing time by 21.4% compared to low-pressure polishing. In addition, the gallium penetration polishing method dispersed the stress concentration near the microcracks and inhibited the growth of micro-cracks during the polishing process, which has been verified by the surface morphology analysis of the workpieces.

Production of glass-ceramics from MSW-fly ash and Dexing copper mine-tailing: Crystallization kinetics, structure, properties and immobilization of heavy metals

To reduce the environmental pollution from MSW-fly ash and Dexing copper mine-tailing and realize their maximum utilization, this research used them to synthesize novel eco-friendly glass-ceramics. Effects of different nucleation-crystallization temperatures on the crystal evolution, microstructure, properties, leaching behavior of heavy metals were discussed. The findings indicate that the crystallization activation energy E is 381 kJ/mol, and the crystallization mechanism is two-dimensional crystallization controlled by diffusion with an increasing nucleation rate. The difference in the nucleation-crystallization temperature will affect the precipitation and growth of crystal (CaAl2Si2O8) in this glassy system, and further affect the microstructure and properties of the prepared glass-ceramics. Furthermore, because the glass-ceramics is the combination of glass and crystal, an obvious immobilization effect for heavy metals Fe, Mn and Cr can be obtained in our glass-ceramics. Apart from the high immobilization efficiencies for heavy metals, our glass-ceramics also show low density (2.715–2.761 g/cm3) and water absorption (0.026–0.045%), high Vickers hardness (5.72–6.39 GPa), good chemical stability (kH2SO4: 3.68–28.72%, kNaOH: 0.01–0.96%), which confirms the potential and feasibility of the MSW-fly ash-Dexing copper mine-tailing-derived glass-ceramics as building decoration material.

Additive manufacturing by laser powder bed fusion and thermal post-treatment of the lunar-regolith-based glass-ceramics for in-situ resource utilization

Powder bed fusion is one of the most promising additive manufacturing approaches for in-situ resource utilization (ISRU) in the following lunar exploitation missions. However, the harsh conditions for energy supply and equipment operation on the lunar surface and the amorphization of materials due to rapid heat-cooling cycles could hinder the efforts to produce high-quality lunar regolith-based products. Laser powder bed fusion (LPBF) with large laser spot sizes and low scan speeds were used to print the glassy lunar regolith simulant (LRS) precursors. Then the thermal post-treatment was carried on to transform the LRS precursors into glass–ceramic products. The precursors and glass–ceramic samples' microstructure, mechanical properties, and thermophysical properties were investigated. The results indicated that the acceptable range of volumetric energy density (VED) for the LPBF process of lunar regolith was from 3.5 to 4.3 J/mm3. The porous structure resulting from the large molten pools leads to low thermal conductivities and an acceptable strength compromise. The glassy precursors formed augite phase-dominated LRS glass-ceramics at 823 °C during thermal post-treatment and augite-plagioclase polycrystalline LRS glass-ceramics with better mechanical properties at 1100 °C. The increase of the augite phases precipitation contributed to the strength enhancement, and the grain coarsening caused by the prolonged crystallization process at 1100 °C would reduce the strength. The average compressive strength, fracture toughness, and Vickers hardness of the LRS glass-ceramics could reach 50.71 MPa, 1.49 MPa·m1/2, and 897.91 HV1/15, respectively. This multi-process method of laser powder bed fusion of glass-ceramics can maximize the application potential of the ubiquitous lunar regolith in future in-situ additive manufacturing to produce lunar regolith-based building materials for different stages of future lunar exploitation missions.

Strength characteristics of lightweight concrete based on granular foam glass ceramics

Introduction. Over the past 20–30 years, a wide range of effective porous aggregates with a high content of glass phase of various types and low-heat-conducting lightweight concretes of various structures based on them has been developed.In recent years, JSC Research Center of Construction has developed a new highly efficient single-stage technology for the production of porous granular foam glass ceramics (UCS). It is based on the production of raw granules by mixing and granulating a highly porous powder of opal-cristobalite rock with a sodium-containing solution. This ensures the maximum area of the interfacial boundary, the most uniform distribution of all components at the micro level and, as a result, ensures glass formation at a temperature that does not exceed the foaming interval of the finished glass phase.The aim of the publication is to study the problems of the features of the strength characteristics of lightweight concrete on granular foam glass ceramics.Materials and methods. The strength of cubes made of light concrete on the UCS under compression (R) was determined on samples with a size of 10 × 10 × 10 cm and 7 × 7 × 7 cm according to State Standard 10180-2012 with an assessment of strength according to State Standard 18105-2018.The prismatic strength coefficient (Kpp) was determined by the results of compression tests of samples-prisms with dimensions of 10 × 10 × 40 cm and 7 × 7 × 28 cm and samples made from the same batch-cubes with dimensions of 10 × 10 × 10 cm and 7 × 7 × 7 cm.Bending tensile strength (Rtb) (Figure 2) and splitting strength (Rtt) were determined, respectively, on 10 × 10 × 40 cm prism samples and 10 × 10 × 10 cm cube samples according to State Standard 10180-2012 with an assessment of strength values according to State Standard 18105-2018.Axial tensile strength (Rtb) and splitting strength (Rtt) were determined, respectively, on prism samples measuring 7 × 7 × 28 cm according to State Standard 10180-2012. The strength of the prisms (prismatic strength, Rb) was determined on samples of prisms 10 × 10 × 40 cm according to State Standard 24452-80.Results. The article presents the results of experimental and theoretical studies of the basic strength properties of thermal insulation and structural-thermal insulation lightweight concrete on granulated foam ceramic (UCS) with a density of 500 to 800 kg/m3, as well as structural lightweight concrete with a density of up to 1700 kg/m3 of optimal compositions (prismatic compressive strength, prismatic strength coefficient, axial tensile strength, tensile strength during bending and splitting).Various dependencies on the evaluation of the experimental data obtained are analyzed and recommendations are given for inclusion in regulatory documents, in particular, in SP 351.1325800.2017 "Concrete and reinforced concrete structures made of light concrete. Design rules".Conclusions. Experimental data have been obtained on a higher prismatic strength coefficient for lightweight concrete at the UCS, which in the future may be the basis for increasing the standard design strength resistance under axial compression for this type of lightweight concrete.The values and formulas for determining the prismatic strength and the prismatic strength coefficient of light concrete of the tested compositions at the UCS can be used in the calculation and design of large-format wall panels of a new type.Experimental and calculated data on the tensile strength of the tested compositions of lightweight concrete of a porous structure at the UCS have been obtained, which can be taken into account when adjusting regulatory documents.When using lightweight concrete of a porous structure on the UCS to increase the shrinkage crack resistance of such concrete for enclosing structures, it is advisable to use dispersed reinforcement with polymer fiber, which also increases the heat-protective properties of such structures. The article presents the results of studies of the main strength properties of thermal insulation and structural-thermal insulation lightweight concretes on the UCS with a density of 500 to 800 kg/m3, as well as structural lightweight concretes with a density of up to 1700 kg/m3 of optimal compositions.Various dependencies on the evaluation of the experimental data obtained are analyzed and recommendations are given for inclusion in regulatory documents, in particular, in SP 351. 1325800.2017 "Concrete and reinforced concrete structures made of light concrete. Design rules".

Al-26 and O-18 tracer diffusion in a titania-coated sodium aluminosilicate glass

Although TiO2 is a common nucleating agent in the production of aluminosilicate glass-ceramics, its role as a catalyst for the nucleation of the functional crystal remains unclear. Therefore, the Ti, Al and O mobility was studied in situ using 26Al and 18O tracer diffusion and Ti chemical diffusion experiments in an aluminosilicate melt of albite composition. The albite glass serves as a surrogate for lithium and magnesium aluminosilicate glass-ceramic compositions, as it allows to study atomic mobilities free of crystallisation artefacts. The depth profiles showed that Al mobility increased significantly and became comparable to that of oxygen when Ti simultaneously diffused into the glass. In the absence of Ti, the diffusivity of Al was two orders of magnitude lower than that of oxygen. The co-diffusion coefficients of Ti and Al seem to confirm a proposed preferential structural linkage between Al and Ti species in the network structure of aluminosilicate melts.

Er/Yb co-doped LiYF4 transparent oxyfluoride glass-ceramics with up-conversion optical properties

Transparent oxyfluoride glass-ceramics doped with rare earth ions (RE3+) are promising materials for photoluminescence up- and down-conversion. In this study, glass compositions within the system 40SiO2–25Al2O3–18Li2O–7LiF–10YF3 (mol.%) doped with ErF3 and codoped with ErF3/YbF3 were prepared by melt-quenching method and subjected to thermal treatment at temperatures above glass transition (Tg + 35 °C) for long dwell times to obtain the corresponding glass-ceramics. The formation of LiYF4 and LiAlSiO4 nanocrystals was confirmed by XRD analysis after thermal treatment at 540 °C for 20 h. The increase in the treatment time up to 80 h resulted in the enhancement of the UC luminescence yield and the decrease of the Red to Green ratio (R/G) emission intensity. Due to the nano-sized crystals, the glass-ceramic products were transparent (%T) in near-infrared (NIR) and visible spectral region with %T remaining approximately 85% and 75%, respectively, after 20 h treatment. However, the visible window transparency reduced, with %T dropping to around 50% after 80 h due to the increase in crystal size and crystalline fraction. The influence of Yb3+ co-doping on the up-conversion (UC) luminescence has been investigated in the glass-ceramics and compared to the parent glasses, confirming that Yb3+ ions were also a key factor for facilitating up-conversion via energy transfer (ET), leading to a greater luminescence yield than for Er3+ single doped glass-ceramics and tuning of R/G intensities.

Production of sintered glass-ceramic composites from low-cost materials

Considering that wastes are harmfull for the environment and human health due to certain physical, chemical and biological reasons; the necessity of systematic implementation of waste management comes to the fore. Waste management provides advantages to for industrial manufacturing with less pollut on, cheaper and competitively superior products. With the waste recycling, the needs for raw materials and the impact of production on the environment will decrease. This study proposed to produce low-cost sintered glass-ceramic composite by adding a mixture of molten mining tailings, recycled glasses and alumina platelets at different rates. The results showed that glass-ceramic composite made by 50 wt % molten tailings, 25 wt % recycled borosilicate glass and 25 wt % alumina platelets exhibited the best properties (2.39 g/cm3 bulk density, 0.22 ± 0.01% water absorption and 84± 9 MPa bending strength). In this study, considering the consumptions of raw material resources, it was seen that glass and mine residues can be used as secondary raw materials in glass ceramic composite production when cost and environmental issues are matter.

A novel and clean utilization of multiple solid wastes to produce foam glass-ceramic

Direct materialisation is a large-scale solid waste utilisation approach with economic and environmental benefits. This study explored a novel process for the utilisation of multiple solid wastes, including fly ash, blast furnace slag and desulphurisation gypsum, for foam glass–ceramic preparation. The high-temperature decomposition reactions of desulphurisation gypsum were analysed to investigate its suitability as a foaming agent. The effects of the sintering temperature during the preparation process and the raw material composition on the properties of the prepared foam glass–ceramic were investigated. The optimum parameters were a desulphurisation gypsum addition amount of 7 wt% and a sintering temperature of 1,200 °C, while the corresponding bulk density, thermal conductivity and compressive strength were 1.21 g/cm3, 0.153 W/m K and 11.23 MPa, respectively. Finally, the migration and transformation of heavy metals during the preparation process and the leaching behaviour of heavy metals from the final material were analysed. The recycling of multiple solid wastes for foam glass–ceramic production has significant economic and environmental benefits. The excellent thermal insulation and strength properties of foam glass–ceramic make them suitable for manufacturing wall insulation materials.

Utilization of gasification slag and petrochemical incineration fly ash for glass ceramic production.

This study investigated glass ceramics produced using coal gasification slag (CGS) and petrochemical incineration fly ash (PIFA) to immobilize hazardous heavy metals such as Cr and As. However, the crystallization kinetics and stabilization behavior mechanism of different heavy metals in the petrochemical incineration fly ash-derived glass-ceramics remains unclear. And X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and inductively coupled plasma mass spectrometry were used to characterize glass and crystalline products. In this paper, we reported the crystallization kinetics and chemical leaching characteristics of the glass ceramic. A low crystallization activation energy of 121.49kJ/mol was achieved from crystallization peak of several different heating rates around 850°C, implying that it is easier to produce the glass ceramics at that temperature. The Avrami parameter of the former crystallization was determined to be 1.23 ± .12, which indicated two-dimensional crystal growth with heterogeneous nucleation. The toxicity characteristic leaching procedure results indicated that the heavy metals were well solidified, and that the leaching concentration was significantly lower than the limit specified by governmental agencies. The potentially toxic element index of the parent glass and the two glass ceramics were 11.7, 5.8, and 3.6, respectively. Therefore, the conversion of hazardous petrochemical incineration fly ash and other solid waste into environmentally friendly glass ceramics shows considerable potential and reliability.

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 glassceramics 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 glassceramic products and their corrosion resistance in an acidic environment were measured and compared in this study.