scholarly journals Thermal evolution effects on the properties of converting Cs-polluted soil into pollucite-base glass-ceramics for radioactive cesium immobilization

2021 ◽  
Author(s):  
Yong Yang ◽  
Xin Cao ◽  
Lifen Shi ◽  
Zhengyi Zhang ◽  
Pingping Wang ◽  
...  
Keyword(s):  
Thermal Evolution ◽  
Glass Ceramics ◽  
Polluted Soil ◽  
Radioactive Cesium ◽  
Base Glass ◽  
Cesium Immobilization

A novel method to convert Cs-polluted soil into pollucite-base glass-ceramics for Cs immobilization

2020 ◽  
Vol 385 ◽  
pp. 123844 ◽  
Author(s):  
Yong Yang ◽  
Tianhe Wang ◽  
Zhengyi Zhang ◽  
Zhenkun Ke ◽  
Chuanli Shan ◽  
...  
Keyword(s):  
Glass Ceramics ◽  
Polluted Soil ◽  
Base Glass ◽  
Novel Method

scholarly journals Development of Extraction Technique for Radioactive Cesium in Polluted Soil

2014 ◽  
Vol 24 (4) ◽  
pp. 119-124 ◽  
Author(s):  
Yuki NOGUCHI ◽  
Toshiyuki KIDA ◽  
Eiichi KATO ◽  
Kikuo SHIMIZU ◽  
Mitsuru AKASHI
Keyword(s):  
Polluted Soil ◽  
Extraction Technique ◽  
Radioactive Cesium

Microstructure and Crystallization of MAS Glass-Ceramics Containing Alkali Oxides

2010 ◽  
Vol 177 ◽  
pp. 437-440
Author(s):  
Zhuo Hao Xiao ◽  
Jian Er Zhou ◽  
Yong Qing Wang
Keyword(s):  
Heat Treatment ◽  
Glass Ceramics ◽  
Melt Quenching ◽  
Base Glass ◽  
Sio2 Glass ◽  
Sio2 System ◽  
Treatment Conditions ◽  
Strength Tests ◽  
Alkali Oxides ◽  
Regular Network

MgO-Al2O3-SiO2 glass-ceramics containing 4.0w% alkali oxides were prepared by conven- tional melt quenching technique. The effects of heat treatment conditions on crystal types, microstructure and break strength of the glass-ceramics were studied by DSC, XRD, SEM and break strength tests. The main crystallization phases of this glass system are β-quartz (Li2-2xMgxAl2Si3O10) and β-Spodumene, no cordierite phase found. The glass-ceramics possessed a regular network-shaped microstructure feature formed by pyroxene crystals. With the increase of temperature, the β-Quartz around pyroxene crystals converted into β-spodumene and the regular network-shaped microstructure feature getting weaker and disappeared. The average break strength of the glass-ceramics containing no cordierite crystals based on MgO2-Al2O3-SiO2 system is about 150MPa, which is much high than the base glass.

scholarly journals Impact of Morphology and Microstructure on the Mechanical Properties of Ge-As-Pb-Se Glass Ceramics

2020 ◽  
Vol 10 (8) ◽  
pp. 2836 ◽  
Author(s):  
Rashi Sharma ◽  
Rebecca Welch ◽  
Myungkoo Kang ◽  
Claudia Goncalves ◽  
Cesar Blanco ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Vickers Hardness ◽  
Glass Ceramic ◽  
Volume Fraction ◽  
Glass Ceramics ◽  
Post Heat Treatment ◽  
Base Glass ◽  
Parent Glass ◽  
Crystal Phases

The impact of base glass morphology and post heat-treatment protocol on the mechanical properties (Vickers hardness and Young’s modulus) of a multi-component glass-ceramic was examined. Two parent chalcogenide glasses with identical composition but varying morphology (homogeneous and phase separated) were evaluated for their mechanical properties following identical thermal processing to induce crystallization. The nucleation and growth rates of the starting materials were compared for the two glasses, and the resulting crystal phases and phase fractions formed through heat treatment were quantified and related to measured mechanical properties of the glass ceramics. The presence of a Pb-rich amorphous phase with a higher crystal formation tendency in the phase-separated parent glass significantly impacted the volume fraction of the crystal phases formed after heat-treatment. Pb-rich cubic crystal phases were found to be dominant in the resulting glass ceramic, yielding a minor enhancement of the material’s mechanical properties. This was found to be less than a more moderate enhancement of mechanical properties due to the formation of the dominant needle-like As2Se3 crystallites resulting from heat treatment of the homogeneous, commercially melted parent glass. The greater enhancement of both Vickers hardness and modulus in this glass ceramic attributable to the high-volume fraction of anisotropic As2Se3 crystallites in the post heat-treated commercial melt highlights the important role base glass morphology can play on post heat-treatment microstructure.

Effect of Glass Ceramic Crystallinity on the Formation of Simulated Apatite Layers

2006 ◽  
Vol 514-516 ◽  
pp. 1039-1043 ◽  
Author(s):  
Nuno A.F. Almeida ◽  
Maria Helena F.V. Fernandes
Keyword(s):  
Glass Ceramics ◽  
Apatite Layer ◽  
Silicate Glasses ◽  
Layer Formation ◽  
Volume Percent ◽  
Base Glass ◽  
Heat Treated ◽  
Phosphate Phase ◽  
Calcium Magnesium ◽  
Kinetics Of

In silicate glasses the kinetics of apatite layer formation is usually rapid but the adhesion to the base glass is poor. Glass ceramics promote a stronger bonding between layer and substrate but decrease the rate of the apatite layer formation. In this work a glass of composition (wt%) 54,89%C3P-24,81%SiO2-20,30%MgO has been studied. This glass was heat treated at four temperatures (840 °C, 870 °C, 890 °C and 910 °C) to obtain glass ceramics with different contents of the same crystalline phase. A calcium magnesium phosphate phase was formed in all glass ceramics in a volume percent increasing with temperature. The apatite layer precipitated after immersion in simulated body fluid (SBF) formed faster on the glass than on the glass ceramics and a decrease in the amount of apatite formed was observed with the increase in crystallinity. It was generally concluded that heat treatment can turn a reactive glass into glass ceramics of different surface behaviors, from bioactive to quasi bio inert materials.

Zn2+- Controlled Crystallization and Microstructure in K-Li-Mg-B-Si-Al-F Glass

MRS Advances ◽  
2018 ◽  
Vol 3 (60) ◽  
pp. 3525-3533 ◽  
Author(s):  
Mrinmoy Garai ◽  
Anoop K. Maurya ◽  
Shibayan Roy
Keyword(s):  
Heat Treatment ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Ceramic ◽  
Vickers Microhardness ◽  
Glass Ceramics ◽  
Network Modifier ◽  
Base Glass ◽  
Controlled Crystallization

Abstract Text:The crystallization of (9-X) K2O-1Li2O-12MgO-10B2O3-40SiO2-16Al2O3-12MgF2-X PbO/BaO/ZnO (X =0/5) composition (wt.%) were studied by means of dilatometry, DSC, XRD, SEM and microhardness analysis. Density of base K-Li-Mg-B-Si-Al-F glass (2.59 g.cm–3) is found to be increased on addition of the network modifier oxides PbO, BaO and ZnO content. Addition of Pb2+, Ba2+ and Zn2+ furthermore increased the glass transition temperature (Tg.). A characteristic exothermic hump is found to be appeared in DSC thermograph at the temperature range 800-950°C; and that is ascribed to the formation of crystalline phase fluorophlogopite mica, KMg3(AlSi3O10)F2. Opaque glass-ceramics were prepared from K-Li-Mg-B-Si-Al-F glasses (with and without containing PbO, BaO and ZnO content) by controlled heat-treatment at 1000°C. Interlocked type microstructure combined of flake like fluorophlogopite mica crystals is obtained in ZnO-containing K-Li-Mg-B-Si-Al-F glass-ceramic; and such microstructural pattern is ascribed to cause large thermal-expansion (>11.5×10-6/K, 50-800°C).Vickers Microhardness of base glass-ceramic (5.12 GPa) is increased when contains ZnO (5.26 GPa). ZnO-containing boroaluminosilicate glass-ceramic is, hence, considered with potential interest as they can exhibit the microcrack resistivity in high temperature recycling operation (like SOFC).

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

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Z.S. Aliyu
Keyword(s):  
Glass Ceramic ◽  
Minimum Weight ◽  
Glass Ceramics ◽  
Aluminosilicate Glass ◽  
Base Glass ◽  
Ceramic Samples ◽  
Melting Technique ◽  
The Matrix ◽  
Quaternary Base ◽  
Tio2 Addition

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.

Deformation and fracture of mica-containing glass-ceramics in Hertzian contacts

1994 ◽  
Vol 9 (3) ◽  
pp. 762-770 ◽  
Author(s):  
Hongda Cai ◽  
Stevens Marion A. Kalceff ◽  
Brian R. Lawn
Keyword(s):  
Glass Ceramic ◽  
Material Removal ◽  
Glass Ceramics ◽  
Fatigue Properties ◽  
Base Glass ◽  
Compressive Stresses ◽  
Contact Loads ◽  
Deformation And Fracture ◽  
The Matrix ◽  
Microstructural Design

The Hertzian indentation response of a machinable mica-containing glass-ceramic is studied. Relative to the highly brittle base glass from which it is formed, the glass-ceramic shows evidence of considerable “ductility” in its indentation stress-strain response. Section views through the indentation sites reveal a transition from classical cone fracture outside the contact area in the base glass to accumulated subsurface deformation-microfracture in the glass-ceramic. The deformation is attributed to shear-driven sliding at the weak interfaces between the mica flakes and glass matrix. Extensile microcracks initiate at the shear-fault interfaces and propagate into the matrix, ultimately coalescing with neighbors at adjacent mica flakes to effect easy material removal. The faults are subject to strong compressive stresses in the Hertzian field, suggesting that frictional tractions are an important element in the micromechanics. Bend-test measurements on indented specimens show that the glass-ceramic, although weaker than its base glass counterpart, has superior resistance to strength degradation at high contact loads. Implications of the results in relation to microstructural design of glass-ceramics for optimal toughness, strength, and wear and fatigue properties are discussed.

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