scholarly journals Study of The Effect of TiO2 Addition On The Crystalline Phases, Structure and Chemical Durability of a Nuclear Glass Ceramic

2021 ◽  
Author(s):  
Rafika SOUAG ◽  
Nour elhayet KAMEL ◽  
Dalila Moudir ◽  
Yasmina MOUHEB ◽  
Fayrouz Aouchiche
Keyword(s):  
Glass Ceramic ◽  
Glass Ceramics ◽  
Ceramic Materials ◽  
Chemical Durability ◽  
Aluminosilicate Glass ◽  
High Level Waste ◽  
X Ray Diffraction ◽  
Complex Chemical Composition ◽  
High Level ◽  
Selection Of

Abstract This study focused on the effect of TiO 2 addition on the crystallines phases’ formation, structure and chemical durability of a nuclear glass ceramic constituted by an aluminosilicate glass in the system: SiO2-Al2O3-CaO-MgO-ZrO2-TiO2 . The materials with four contents of TiO2 , ranging from 4.11 to 7.11 wt.%, are synthesized by a discontinuous method,. For the whole of materials, X-ray diffraction analysis allow identifying an aluminosilicate belonging to pyroxenes silicates family as a main phase, powelite and calzirtite. Both SEM and DTAanalyses confirmed these results. The materials FTIR analysis reveals the glass ceramics complex chemical composition. MCC1 and MCC2 tests, performed on selected glass ceramic materials, indicate that the materials with 4.11 and 5.11 wt.% TiO2 are the most durable against Si, Al, Mg and Ce elements release, in MCC2 test; The results make conclusions valuable on the selection of such glass ceramics as candidate for the disposal of high-level waste.

Experimental Glass-Ceramic Products to Immobilize ICPP HLW

1987 ◽  
Vol 112 ◽  
Author(s):  
Roseanne S. Baker ◽  
Bruce A. Staples ◽  
Dieter A. Knecht ◽  
Julius R. Berreth
Keyword(s):  
Glass Ceramic ◽  
Hot Isostatic Pressing ◽  
Glass Ceramics ◽  
High Level Waste ◽  
Processing Plant ◽  
Chemical Processing ◽  
Stabilized Zirconia ◽  
Experimental Glass ◽  
Ceramic Glass ◽  
High Level

AbstractCandidate products are being evaluated to immobilize the routinely calcined waste at the Idaho Chemical Processing Plant (ICPP). A potential product with minimal volume for immobilizing ICPP high-level waste (HLW) for final disposal is a high-waste-loading and high-density glass-ceramic. Glass-ceramics are formed by Hot Isostatic Pressing (HIPing) the HLW with selected additives, such as SiO2, B2O3, Li2O, Na2O, and Y2O3. Glass-ceramic products have been formed with calcine loa ings up to 80 wt% and densities up to 3.4 g/cm3. Crystalline phases observed in the glass-ceramic products include calcium fluoride, monoclinic and cubic zirconia, calcium- and yttrium-stabilized zirconia, and zircon. An interstitial amorphous phase also exists consisting of the oxides of silicon, aluminum, boron, and alkalis. The glass-ceramic waste forms give leach rates comparable to simulated HLW glass products.

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 and Mechanical Properties of Glass-Ceramic from Silicon Slag

2014 ◽  
Vol 953-954 ◽  
pp. 1643-1648
Author(s):  
Hang Li ◽  
Li Qiang Liu ◽  
Min Jing ◽  
Zhi Gang Wang ◽  
Zheng Wang ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Mechanical Performance ◽  
Glass Ceramics ◽  
Ceramic Materials ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Talcum Powder ◽  
X Ray ◽  
Glass Ceramic Materials ◽  
Spherical Grains

The glass-ceramic materials were produced from silicon slag with the addition of talcum powder and TiO2 by melting them in an electrically heated furnace and subsequent heat treatment at various temperatures and time. The microstructure and crystallization behaviors of glass–ceramics have been investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). With the increase of silicon slag content, the sequent precipitate phase is: krinovite Na (Mg1.9Fe0.1)Cr (SiO)3O, pseudobrookite Fe2TiO5 and anorthite Ca (Al2Si2O8), enstatite ferroan MgFeSi2O6, and albite Na (AlSi3O8). The shape of crystals was spherical grains. The glass–ceramic sample obtained from 70% silicon slag had the excellent mechanical performance including flexural strength of 200.45 MPa and Vickers micro hardness of 909.72 MPa.

scholarly journals Preparation and properties of Li2O-BaO-Al2O3-SiO2 glass-ceramic materials

2014 ◽  
Vol 8 (4) ◽  
pp. 203-210 ◽  
Author(s):  
Gamal Khater ◽  
Maher Idris
Keyword(s):  
Solid Solution ◽  
Water Absorption ◽  
Glass Ceramic ◽  
Density Measurement ◽  
Glass Ceramics ◽  
Ceramic Materials ◽  
Optical Microscope ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
Glass Ceramic Materials

The crystallization of some glasses, based on celsian-spodumene glass-ceramics, was investigated by different techniques including differential thermal analysis, optical microscope, X-ray diffraction, indentation, microhardness, bending strengths, water absorption and density measurement. The batches were melted and then cast into glasses, which were subjected to heat treatment to induce controlled crystallization. The resulting crystalline materials were mainly composed of ?-eucryptite solid solution, ?-spodumene solid solution, hexacelsian and monoclinic celsian, exhibiting fine grains and uniform texture. It has been found that an increasing content of celsian phase in the glasses results in increased bulk crystallization. The obtained glass-ceramic materials are characterized by high values of hardness ranging between 953 and 1013 kg/mm2, zero water absorption and bending strengths values ranging between 88 and 126MPa, which makes them suitable for many applications under aggressive mechanical conditions.

Phase Relations and Chemical Durability of Ceramics in the Pseudo-Binary System: CaZrTi2O7–GdAlO3

2003 ◽  
Vol 807 ◽  
Author(s):  
N. P. Mikhailenko ◽  
A. V. Ochkin ◽  
S. V. Stefanovsky ◽  
O. I. Kirjanova
Keyword(s):  
Electron Microscopy ◽  
Binary System ◽  
Chemical Durability ◽  
Phase Relations ◽  
High Level Waste ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceramic Samples ◽  
High Level ◽  
System 1

ABSTRACTPhase relations in a pseudo-binary system (1-x) CaZrTi2O7- x GdAlO3 suggested for immobilization of a zirconium - rare earth – actinide fraction of high level waste were studied with X-ray diffraction and electron microscopy. Zirconolite and perovskite were found to be major phases in the ceramic samples prepared by cold pressing and sintering at 1400 and 1500 °C. At relatively low perovskite content (x < 0.5) zirconolite is the major host for Gd, which is considered as a trivalent surrogate for Am and Cm. At higher perovskite content, perovskite becomes the major host for Gd. Zirconolite is the major host phase for corrosion products (Al, Fe, Ti, Zr). Leach rates of Gd, 238Pu, and 241Am from the ceramics studied are 10−4–10−5 g/(m2d).

scholarly journals Study of the effect of Ca/Mg alkali-oxides ratio on the structure of a glass-ceramic based on an aluminosilicated glass containing 2wt.% of zirconolite crystalline phase

2014 ◽  
Vol 46 (3) ◽  
pp. 377-383
Author(s):  
R. Souag ◽  
N. Kamel ◽  
Y. Mouheb ◽  
M. Hammadi ◽  
Z. Kamel ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Glass Ceramics ◽  
Xrd Analysis ◽  
Aluminosilicate Glass ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Alkali Oxides ◽  
Scanning Electron

New nuclear glass-ceramics are extensively studied for the radioactive waste confinement, due to the double confinement conferred by the glass-ceramics. In this study, a glass-ceramic constituted by an aluminosilicate glass in the system: SiO2-Al2O3-CaO-MgOZrO2-TiO2, containing 2wt.% of Ca0.83Ce0.17ZrTi1.66Al0.34O7 zirconolite, has been synthesized by the discontinuous method. Cerium, an actinide surrogate is introduced both in the glass and ceramic phases. The synthesis is performed by a double melting at 1350?C, followed by a nucleation at 564?C, during 2 h, and a crystal growth at 1010?C during 3 h. Then effect of Ca/Mg ratio on the distribution of the crystalline network in the material was studied for Ca / Mg ratios ranging from 0.4 to 5.5. For the whole of the materials, Archimedes density is about 2.80 g/cm3. X-ray diffraction (XRD) analysis shows that the increase of Ca/Mg ratio leads to the increase of aluminosilicated crystalline phases with high Ca contents; the materials molar volumes remaining constant. The zirconolite phase is not affected by these additive aluminosilicated phases. The scanning electron microscopy analysis (SEM) coupled with energy dispersive X-ray (EDX) analysis confirmed these results; and shows the uniformity of distribution of the ceramics in the bulk of the materials.

scholarly journals Formation of nanostructures in Eu3+ doped glass–ceramics: an XAS study

2014 ◽  
Vol 70 (a1) ◽  
pp. C959-C959
Author(s):  
Julio Pellicer-Porres ◽  
Alfredo Segura ◽  
Gema Martínez-Criado ◽  
Ulises Rodríguez-Mendoza ◽  
Víctor Lavín
Keyword(s):  
Amorphous Phase ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Aluminosilicate Glass ◽  
Chemical Information ◽  
Nanocrystalline Phase ◽  
X Ray Diffraction ◽  
Oxyfluoride Glass ◽  
X Ray ◽  
X Ray Absorption

Lead-aluminosilicate oxyfluoride transparent glass–ceramics doped with RE3+ ions have been revealed to be unique in the field of optical material engineering. This kind of material consists of a beta_x000C_-PbF2 fluoride nanocrystalline phase in an aluminosilicate glassy amorphous phase. In this way, the macroscopic properties of this material are characteristic of aluminosilicate glass, whereas the spectroscopic properties of the RE3+ ions remain those of low-phonon-energy fluoride crystals. The optical properties of the RE3+ ions, and therefore their interest for photonic applications, depend on the final environment of these ions in a host matrix. Exploration of the local structure of the Eu3+ ions as well as characterization of the amorphous matrix demands structural techniques that do not rely on long range order. Given the complexity of the system under study, chemical selectivity is also required. In this work [1], we describe the results of x-ray absorption experiments carried out to deduce structural and chemical information in Eu3+ doped, transparent, oxyfluoride glass and nanostructured glass–ceramic samples. The spectra were measured at the Pb and Eu–LIII edges. The Eu environment in the glass samples is observed to be similar to that of EuF3. Complementary x-ray diffraction experiments show that thermal annealing creates _x000C_beta-PbF2 type nanocrystals. X-ray absorption indicates that Eu ions act as seeds in the nanocrystal formation. There is evidence of interstitial fluorine atoms around Eu ions as well as Eu dimers. X-ray absorption at the Pb–LIII edge shows that after the thermal treatment most lead atoms form a PbO amorphous phase and that only 10% of the lead atoms remain available to form _x000C_beta-PbF2 type nanocrystals. Both x-ray diffraction and absorption point to a high Eu content in the nanocrystals. Our study suggests new approaches to the oxyfluoride glass–ceramic synthesis in order to further improve their properties.

Nepheline Precipitation in High-Level Waste Glasses : Compositional Effects and Impact on the Waste Form Acceptability

1996 ◽  
Vol 465 ◽  
Author(s):  
H. Li ◽  
J. D. Vienna ◽  
P. Hrma ◽  
D. E. Smith ◽  
M. J. Schweiger
Keyword(s):  
Chemical Durability ◽  
Primary Phase ◽  
Waste Form ◽  
High Level Waste ◽  
X Ray Diffraction ◽  
Consistency Test ◽  
Compositional Effects ◽  
High Level ◽  
The Impact ◽  
Glass Compositions

ABSTRACTThe impact of crystalline phase precipitation in glass during canister cooling on chemical durability of the waste form limits waste loading in glass, especially for vitrification of certain high-level waste (HLW) streams rich in Na2O and Al2O3. This study investigates compositional effects on nepheline precipitation in simulated Hanford HLW glasses during canister centerline cooling (CCC) heat treatment. It has been demonstrated that the nepheline primary phase field defined by the Na2O-Al2O3-SiO2 ternary system can be used as an indicator for screening HLW glass compositions that are prone to nepheline formation. Based on the CCC results, the component effects on increasing nepheline precipitation can be approximately ranked as Al2O3 > Na2O > Li2O ≈ K2O ≈ Fe2O3 > CaO > SiC2. The presence of nepheline in glass is usually detrimental to chemical durability. Using x-ray diffraction data in conjunction with a mass balance and a second-order mixture model for 7-day product consistency test (PCT) normalized B release, the effect of glass crystallization on glass durability can be predicted with an uncertainty less than 50% if the residual glass composition is within the range of the PCT model.

Effect of Gradual Substitution of CaO by SrO in Glass-Ceramic Materials of the System SiO2 - Al2O3 - CaF2 - RO (R = Ca, Mg, Sr)

2012 ◽  
Vol 1373 ◽  
Author(s):  
M. Garza-García ◽  
J. López-Cuevas ◽  
C.A. Gutiérrez-Chavarría ◽  
N. Piedad-Sánchez ◽  
E. Camporredondo-Saucedo ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Vickers Microhardness ◽  
Glass Ceramics ◽  
Ceramic Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Substitution Level ◽  
Glass Ceramic Materials ◽  
Ceramic Samples ◽  
Crystallization Fraction

ABSTRACTThe density, Vickers microhardness and crystallization fraction of glass-ceramic materials synthesized from parent glasses are determined in which CaO is gradually substituted by SrO. The chemical composition (in mol.%) of the parent glasses is 54SiO2-(23-X)CaO-12MgO-5Al2O3-6CaF2-XSrO, where X is the employed CaO substitution level (X = 0, 3, 6 and 9 mol.%, with X = 0 corresponding to the reference material). In order to determine the type of crystallization occurring in the glass-ceramic samples, as well as the crystalline phases formed in them, these are characterized by both Scanning Electron Microscopy (SEM/EDS) and X-Ray Diffraction (XRD). Independently of the CaO substitution level employed, the glass-ceramics show the formation of a solid solution corresponding to diopside-type pyroxene, with chemical formula Ca(Mg,Al)(Al,Si)2O6, as a single crystalline phase. The synthesized glass-ceramic materials with the reference composition show the highest Vickers microhardness and crystallization fraction, as well as the lowest density.

Glass-Ceramic Waste Forms for Immobilizing Plutonium

1996 ◽  
Vol 465 ◽  
Author(s):  
T. P. O'Holleran ◽  
S. G. Johnson ◽  
S. M. Frank ◽  
M. K. Meyer ◽  
M. Noy ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
High Level Waste ◽  
Processing Plant ◽  
Chemical Processing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceramic Waste ◽  
Waste Forms ◽  
Diffraction Patterns ◽  
High Level

ABSTRACTResults are reported on several new glass and glass-ceramic waste formulations for plutonium disposition. The approach proposed involves employing existing calcined high level waste (HLW) present at the Idaho Chemical Processing Plant (ICPP) as an additive to: 1) aid in the formation of a durable waste form and 2) decrease the attractiveness level of the plutonium from a proliferation viewpoint. The plutonium, PuO2, loadings employed were 15 wt% (glass) and 17 wt% (glass-ceramic). Results in the form of x-ray diffraction patterns, microstructure and durability tests are presented on cerium surrogate and plutonium loaded waste forms using simulated calcined HLW and demonstrate that durable phases, zirconia and zirconolite, contain essentially all the plutonium.

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