Lanthanum modification of crystalline phases and residual glass in augite glass ceramics produced with industrial solid wastes

2019 ◽  
Vol 524 ◽  
pp. 119638 ◽  
Author(s):  
Hua Chen ◽  
Baowei Li ◽  
Ming Zhao ◽  
Xuefeng Zhang ◽  
Yongsheng Du ◽  
...  
Keyword(s):  
Glass Ceramics ◽  
Solid Wastes ◽  
Residual Glass ◽  
Crystalline Phases

scholarly journals Ferrosilicate glass ceramics based on wastes from ore concentration

2021 ◽  
pp. 95-103
Keyword(s):  
Surface Layer ◽  
Iron Ore ◽  
Glass Ceramics ◽  
Redox Conditions ◽  
Glass Technology ◽  
Crystalline Phases ◽  
Reducing Conditions ◽  
Deep Layers ◽  
Hematite Fe2o3 ◽  
Crystallization Of Glass

We showed in this work that there is a possibility of recycling the wastes derived from iron ore concentration by using glass technology. The compositions of new glass ceramics with high technological and decorative properties were developed. The influence of Al2O3, MgO and Na2O additives to the waste from ore benefication on the parameters of the synthesized glass and its crystallization products was studied. The optimal temperatures of synthesis, annealing and crystallization of glass samples in the systems (Fe2O3–FeO)–SiO2–Al2O3–Na2O and (Fe2O3–FeO)–SiO2–Al2O3–MgO were shown to be 1450100С, 500–6000С and 700–8000C, respectively. It was established that the redox conditions of crystallization of glasses in the system (FeO–Fe2O3)–SiO2–Al2O3–Na2O strongly affect the nature of the iron-containing phases that are formed: oxidative conditions favors the formation of hematite (Fe2O3) and aegirinite (Na2OFe2O34SiO2), whereas reducing conditions contributes to the formation of wustite (FeO) and fayalite (2FeOSiO2). In the system (FeO–Fe2O3)–SiO2–Al2O3–MgO under both oxidative and reducing conditions of crystallization, the same crystalline phases appear: olivine (2(Mg,Fe)OSiO2), hercin (FeOAl2O3) and iron metasilicate (FeOSiO2). It was shown that the crystallization of samples under reducing conditions allows producing materials with higher microhardness. The surface layer of glasses and glass ceramics exhibited less microhardness than their deep layers.

HIPed Tailored Pyrochlore-Rich Glass-Ceramic Waste Forms for the Immobilization of Nuclear Waste

2008 ◽  
Vol 1124 ◽  
Author(s):  
Melody Lyn Carter ◽  
Hui Li ◽  
Yingjie Zhang ◽  
Andrew L Gillen ◽  
Eric R Vance
Keyword(s):  
Nuclear Waste ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Spectroscopic Characterization ◽  
Chemical Durability ◽  
Intermediate Level ◽  
Crystalline Phases ◽  
Waste Forms ◽  
Ceramic Samples

AbstractHot isostatically pressed (HIPed) glass-ceramics for the immobilization of uranium-rich intermediate-level wastes and Hanford K-basin sludges were designed. These were based on pyrochlore-structured Ca(1-x)U(1+y)Ti2O7 in glass, together with minor crystalline phases. Detailed microstructural, diffraction and spectroscopic characterization of selected glass-ceramic samples has been performed, and chemical durability is adequate, as measured by both MCC-1 and PCT-B leach tests.

Structure Characterization of Sintered CaO-Al2O3-SiO2 Glass-Ceramic Reinforced with Spodumene

2013 ◽  
Vol 834-836 ◽  
pp. 309-314
Author(s):  
Zi Fan Xiao ◽  
Jin Shu Cheng ◽  
Jun Xie
Keyword(s):  
Glass Ceramic ◽  
Energy Dispersive Spectrometry ◽  
Crystal Size ◽  
Bending Strength ◽  
Glass Ceramics ◽  
Structure Characterization ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
X Ray

A glass-ceramic belonging to the CaO-Al2O3-SiO2(CAS) system with different composition of spodumene and doping the Li2O with amount between 0~2.5 % (mass fraction) were prepared by onestage heat treatment, under sintering and crystallization temperature at 1120 °C for two hours. In this paper, differential thermal analysis, X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and bending strength test were employed to investigate the microstructure and properties of all samples. β-wollastonite crystals were identified as the major crystalline phases, and increasing Li2O was found to be benefit for the crystallization and tiny crystalline phases remelting, resulting in the content of major crystalline phases increased first and then decreased with increasing the expense of spodumene. Meanwhile, the crystal size can be positively related with the content of Li2O. The preferable admixed dosage of spodumene can be obtained, besides the strength of glass-ceramics can be more than 90 MPa.

Study of Glass-Ceramic Waste Forms

1997 ◽  
Vol 506 ◽  
Author(s):  
S.V. Stefanovsky ◽  
S.V. Ioudintsev ◽  
B.S. Nikonov ◽  
B.I. Omelianenko ◽  
T.N. Lashtchenova
Keyword(s):  
Glass Ceramic ◽  
Glass Composition ◽  
Glass Ceramics ◽  
High Level Waste ◽  
Matrix Glass ◽  
Crystalline Phases ◽  
Cell Parameters ◽  
The Matrix ◽  
High Level ◽  
Similar Unit

ABSTRACTSince the early of the 1990s the method of inductive melting in a cold crucible (IMCC) has been applied at SIA “Radon” for production of various wasteforms, including glasses and Synroc-type ceramics. Sphene-based glass-ceramics composed of glass and crystalline phases were considered as appropriate wasteform for High Level Waste immobilisation. Investigation of two glass-ceramic specimens prepared with the IMCC has been performed using optical microscopy, XRD, SEM/EDS, and TEM methods. The samples produced consist of vitreous and crystalline phases. The vitreous phase consists of two varieties of glass formed by the immiscibility of the initial melt onto two separate liquids. One of the glasses is observed as spherical microinclusions in the matrix glass. The glass of the microspheres are differed from the matrix glass composition by higher contents of Ca, Ti, Ce, Sr, Zr (or Cr), while the matrix glass contains higher amounts of Si, Al, and alkalies. The crystalline phases with sphene- and perrierite-like structures have been also occurred. Their total quantity reaches up to 50 vol.%. The synthetic perrierite has similar unit-cell parameters with its natural mineral analogs with the only exception in two-fold value of c dimension. Zr, Ce, and Sr are incorporated into synthetic sphene and perrierite, while Cs is hosted by the glass phases.

Crystallization Kinetics of β-Spodumene/Cordierite-Based Glass-Ceramics

2016 ◽  
Vol 881 ◽  
pp. 83-88 ◽  
Author(s):  
Rafael Bianchini Nuernberg ◽  
Oscar Rubem Klegues Montedo
Keyword(s):  
Crystallization Kinetics ◽  
Glass Ceramics ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Kinetics Parameters ◽  
Crystalline Phases ◽  
Cordierite Glass ◽  
Thermal And Electrical Properties ◽  
Kinetics Of

This work aims to investigate the crystallization kinetics of β-spodumene/cordierite glass-ceramics. Thus, three glasses with compositions based predominantly on cordierite (C), β-spodumene (L) and in a molar ratio 1:1 of both phases (CL) were prepared. The kinetics parameters such as activation energy for crystallization (ranging from 160 to 358 kJ/mol) and Avrami exponent (ranging from 1.4 to 10.7) were determined by means of non-isothermal methods using differential scanning calorimetry (DSC). Additionally, the samples were crystalized according to DSC analyses and characterized by using x-ray diffraction (XRD). The main detected crystalline phases were β-spodumene to the glass L, cordierite to the glass C and β-quartz, mulite and spinel to the glass CL. Considering the thermal and electrical properties of these crystalline phases, these glass-ceramics have potential use for LTCC (Low Thermal Co-fired Ceramics) applications.

Neutron Diffraction and SEM Study on CaO-Al2O3-SiO2(ZnO-BaO-Na2O) Glass-Ceramics Prepared Under Different Cooling Conditions

2010 ◽  
Author(s):  
Liping Guo ◽  
Jun Xie ◽  
Kai Sun ◽  
Zheng Yang ◽  
Shuoxue Jin ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Tensile Stress ◽  
Glass Ceramics ◽  
Range Order ◽  
Transgranular Fracture ◽  
Residual Glass ◽  
Rapid Cooling ◽  
Cooling Temperature ◽  
Cooling Conditions ◽  
Diffraction Angle

Neutron diffraction and Scanning Electron Microscope (SEM) were employed to study complex two-phase coexistence structure and surface morphology of CaO-Al2O3-SiO2(ZnO-BaO-Na2O) glass ceramics prepared under different cooling conditions. With the rapid cooling temperature decreasing from above 850°C to 750°C and 300°C, the length of the needle-like precipitated β-wollastonite crystal decreased from 30 μm to 15 μm and 5 μm, respectively. Meanwhile, the transgranular fracture appeared and the grain boundary became indistinct in the sample rapidly cooled to 750°C, and the microcracks appeared in the samples rapidly cooled to 300°C and below. These phenomena contribute to the decrease of bending strength for the rapid cooling. Neutron diffraction revealed that the unit cell of precipitated β-wollastonite crystal elongated along its three axes and its volume increased at different cooling conditions. With the decrease of the cooling temperature, the elongation of axes and increase of volume were enhanced, implying that the tensile stress of the β-wollastonite crystal increased. At the same time, intensity of the crystal diffraction peaks increased and atomic temperature factors decreased, which revealed that defects inside a smaller size of crystal granular were less than that in larger one. Amorphous peaks at low diffraction angle did not changed with cooling temperature, showing that the middle-range-order inside residual glass phases were almost the same for all cooling conditions, while intensity of amorphous peaks at high diffraction angle increased notably for samples rapidly cooled to below 850°C, showing that rapid cooling may result in severe short-range-order in residual glass phase, which induced tensile stress of crystalline phase from around amorphous phase and therefore lead to occurrence of transgranular fracture and microcracks. This study suggests that rapid cooling to below 850°C should be avoided in order to obtain preferable mechanical properties for CaO-Al2O3-SiO2(ZnO-BaO-Na2O) glass ceramics.

Preparation of Sintered Glass-Ceramics: A Comparison of Different Binders

2014 ◽  
Vol 563 ◽  
pp. 123-126
Author(s):  
Na Li ◽  
Hong Hai Shen ◽  
Wei Juan Zhang ◽  
Shi Quan Liu
Keyword(s):  
Waste Water ◽  
Polyvinyl Alcohol ◽  
Water Glass ◽  
Glass Powder ◽  
Glass Ceramics ◽  
Solid Wastes ◽  
Fine Grained ◽  
Sintered Glass ◽  
Negative Effect ◽  
Sintering Shrinkage

With the rapid increase of solid wastes and the decrease in natural resources, the reutilization of the wastes has become an urgent need. Sintered glass-ceramics with gehlenite and anorthite as main crystalline phases have been prepared with glass powder made from a waste water flocculate. In this work, different binders, including diluted water glass, polyvinyl alcohol (PVA) solution and kaolin were added to form green bodies for making sintered glasses ceramics. Effects of the binders on the sintering shrinkage of the green bodies, the crystallization of the glass powder upon sintering and the microstructure of the sintered glass-ceramics have been investigated. The results indicate that the kaolin benefits the reduction of the shrinkage and may have negative effect on the formation of glass-ceramics with fine grained crystallites. In contrast, PVA and water glass solutions as binders lead to larger shrinkage values and glass-ceramics with well distributed smaller crystallites.

A quantitative X-ray powder diffraction analysis of the Li2O–SiO2glass–ceramic system

1993 ◽  
Vol 8 (1) ◽  
pp. 29-35 ◽  
Author(s):  
D. W. Tomlin ◽  
D. B. Sullenger ◽  
J. S. Cantrell
Keyword(s):  
Quantitative Analysis ◽  
Diffraction Analysis ◽  
Powder Diffraction ◽  
Intensity Ratio ◽  
Glass Ceramics ◽  
Ceramic System ◽  
Crystalline Phases ◽  
X Ray ◽  
Content Ratio ◽  
External Standard

An X-ray powder diffraction quantitative analysis has been developed to determine the relative amounts of the principal crystalline phases (α-Li2SiO3,α-Li2Si2O5and theα-cristobalite form of SiO2) contained in selected Li2O–SiO2glass-ceramics. The analysis was extended to estimate the amorphous-to-crystalline content ratio of individual samples. The method utilized is an external-standard intensity ratio technique that employs cristobalite, a component common to each sample, for a standard.

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