scholarly journals The Importance of Secondary Phases in Glass Corrosion

1990 ◽  
Vol 212 ◽  
Author(s):  
William L. Ebert ◽  
John K. Bates
Keyword(s):  
Computer Simulations ◽  
Reaction Times ◽  
Microscopic Analysis ◽  
Secondary Phase ◽  
Secondary Phases ◽  
Reaction Behavior ◽  
Glass Corrosion ◽  
Model Glass ◽  
Secondary Phase Formation

ABSTRACTThe analytical expression used to model glass reaction in computer simulations such as EQ6 is compared to the results of experiments used to support the simulations. The expression correctly predicts the acceleration observed in experiments performed at high glass surface area/1eachant volume ratios (SA/V) upon the formation of secondary phases. High resolution microscopic analysis of reacted glass samples suggests that the accelerated nature of the reaction after secondary phase formation is due to changes in the reaction affinity (i.e., is a solution effect) and not a change in the glass reaction mechanism. The composition of solutions in contact with reacted samples reflect the effects of the secondary phases predicted in the model. Experiments which lead to the generation of secondary phases within short reaction times can be used to identify important secondary phases which must be Included in the data base of computer simulations to correctly project long-term glass reaction behavior.

scholarly journals In situ nuclear-glass corrosion under geological repository conditions

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Mathieu Debure ◽  
Yannick Linard ◽  
Christelle Martin ◽  
Francis Claret
Keyword(s):  
Pure Water ◽  
Secondary Phase ◽  
Predictive Modelling ◽  
Diffusion Experiment ◽  
Secondary Phases ◽  
Glass Corrosion ◽  
Geological Repository ◽  
High Level ◽  
Rock Supports

Abstract Silicate glasses are durable materials but laboratory experiments reveal that elements that derive from their environment may induce high corrosion rates and reduce their capacity to confine high-level radioactive waste. This study investigates nuclear-glass corrosion in geological media using an in situ diffusion experiment and multi-component diffusion modelling. The model highlights that the pH imposed by the Callovo–Oxfordian (COx) claystone host rock supports secondary-phase precipitation and increases glass corrosion compared with pure water. Elements from the COx rock (mainly Mg and Fe) form secondary phases with Si provided by the glass, which delay the establishment of a passivating interface. The presence of elements (Mg and Fe) that sustain glass alteration does not prevent a significant decrease in the glass-alteration rate, mainly due to the limited species transport that drives system reactivity. These improvements in the understanding of glass corrosion in its environment provide further insights for predictive modelling over larger timescales and space.

scholarly journals Effects of Radiation Exposure on SRL 131 Composition Glass in a Steam Environment

1993 ◽  
Vol 333 ◽  
Author(s):  
D. J. Wronkiewicz ◽  
C. R. Bradley ◽  
J. K. Bates ◽  
L. M. Wang
Keyword(s):  
Radiation Exposure ◽  
Glass Surface ◽  
Average Rate ◽  
Reaction Times ◽  
Secondary Phase ◽  
Reaction Rates ◽  
Liquid Volume ◽  
Secondary Phase Formation ◽  
Effects Of Radiation ◽  
Doped Glass

ABSTRACTMonoliths of SRL 131 borosilicate glass were irradiated in a saturated air-steam environment, at temperatures of 150°C, to examine the effects of radiation on nuclear waste glass behavior. Half of the tests used actinide and Tc-99 doped glass and were exposed to an external ionizing gamma source, while the remaining glass samples were doped only with uranium and were reacted without any external radiation exposure. The effects of radiation exposure on glass alteration and secondary phase formation were determined by comparing the reaction rates and mineral paragenesis of the two sets of samples.All glass samples readily reacted with the water that condensed on their surfaces, producing two types of smectite clay within the first three days of testing. Additional crystalline phases precipitated on the altered glass surface with increasing reaction times, including zeolites, smectite, calcium and sodium silicates, phosphates, evaporitic salts, and uranyl silicates. Similar phases were produced on both the nonirradiated and irradiated samples; however, the quantity of precipitates was increased and the rate of paragenetic sequence development was accelerated in the latter. After 56 days of testing, the composite smectite layer developed at an average rate of ~0.16 and 0.63 µm/day for the nonirradiated and irradiated samples, respectively. These comparisons indicate that layer development is accelerated approximately four-fold due to the radiation exposure at high glass surface area/liquid volume (SA/V) conditions. This increase apparently occurs in response to the rapid concentration of radiolytic products, including nitric acid, in the thin films of water contacting the sample monoliths.

PH3 Effects on the Electrochemical Degradation of SOFC Anode

2011 ◽  
Author(s):  
Huang Guo ◽  
Gulfam Iqbal ◽  
Bruce S. Kang
Keyword(s):  
Electrochemical Performance ◽  
Secondary Phase ◽  
Anode Surface ◽  
Electrochemical Degradation ◽  
Secondary Phases ◽  
Nickel Phosphate ◽  
Secondary Phase Formation ◽  
Cell Anode ◽  
Fuel Cell Anode ◽  
Ppm Level

Solid Oxide Fuel Cell anode is readily degraded by trace amount of Phosphine (PH3) contaminant that is found in coal-derived syngas. PH3 interacts with the anode material and affects its electrochemical performance by forming secondary phases. In this paper, the influence of the ppm level of PH3 with moisture is investigated on the formation of secondary phases and hence on anode electrochemical performance degradation. Nickel yttria-stabilized zirconia (Ni-YSZ) anode shows immediate and severe electrochemical degradation due to PH3 in moist hydrogen condition attributed to the nickel-phosphate secondary phase formation. Whereas in dry hydrogen condition, nickel-phosphide is preferred to form on the anode surface that shows less deleterious effects on SOFC performance as compared to nickel-phosphate.

Identification of Secondary Phases Formed During Unsaturated Reaction of UO2 with EJ-13 Water

1989 ◽  
Vol 176 ◽  
Author(s):  
J. K. Bates ◽  
B. S. Tani ◽  
E. Veleckis ◽  
O. J. Wronklewicz
Keyword(s):  
Phase Formation ◽  
Secondary Phase ◽  
Yucca Mountain ◽  
Solution Chemistry ◽  
Spent Fuel ◽  
Secondary Phases ◽  
Secondary Phase Formation

ABSTRACTA set of experiments, wherein UO2 has been contacted by dripping water, has been conducted over a period of 182.5 weeks. The experiments are being conducted to develop procedures to study spent fuel reaction under unsaturated conditions that are expected to exist over the lifetime of the proposed Yucca Mountain repository site. One half of the experiments have been terminated, while one half are ongoing. Analyses of solutions that have dripped from the reacted UO2 have been performed for all experiments, while reacted UO2 surfaces have been examined for the terminated experiments. A pulse of uranium release from the UO2 solid, combined with the formation of schoepite on the surface of the UO2, was observed between 39 and 96 weeks of reaction. Thereafter, the uranium release decreased and a second set of secondary phases was observed. The latter phases incorporated cations from the EJ-13 water and include boltwoodite, uranophane, sklodowskite, compreignacite, and schoepite. The experiments are continuing to monitor whether additional changes in solution chemistry or secondary phase formation occurs.

Formation of secondary phases after long-term corrosion of simulated HLW glass in brine solutions at 190 °C

2002 ◽  
Vol 90 (9-11) ◽  
Author(s):  
P. Zimmer ◽  
E. Bohnert ◽  
Dirk Bosbach ◽  
Jae-Il Kim ◽  
E. Althaus
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Glass Powder ◽  
High Level Waste ◽  
Secondary Phases ◽  
Batch Experiments ◽  
Salt Solutions ◽  
Glass Corrosion ◽  
High Level

SummaryThe behavior of rare earth elements (REE) as chemical analogues for actinides during glass corrosion was studied with static long-term batch experiments (7.5 years) at 190 °C. Corrosion tests were carried out using a simulated inactive high level waste (HLW) glass powder. Two different highly concentrated salt solutions (NaCl-rich and MgCl

Corrosion of Waste Glasses in Boom Clay: Studies of Element Concentrations by Sims

1995 ◽  
Vol 412 ◽  
Author(s):  
A. Lodding ◽  
P. Van Iseghem
Keyword(s):  
Composition Dependence ◽  
Secondary Phase ◽  
Boom Clay ◽  
Glass Corrosion ◽  
Secondary Phase Formation ◽  
Sims Analysis ◽  
Corrosion Mechanisms ◽  
Coherent Picture ◽  
Secondary Ion

AbstractIn-situ corrosion tests on nuclear waste glasses in Boom clay provided direct contact glass-clay at 90°C, for periods of 2, 3.5 and 7.5 years. The corroded reference glasses (two R7T7 type glasses, four Pamela type glasses), were studied in terms of SIMS (secondary ion mass spectroscopy) and mass losses.The Al2O3 rich Pamela glasses appear to corrode in a selective-substitutional way, the other glasses dissolve almost congruently. Differences in the corrosion extent between the glasses are associated with compositional differences and secondary phase formation. SIMS analysis provides the reaction layer thickness and the relative element behaviour in this layer. Although relatively few, the data have provided a coherent picture of glass corrosion, in terms of corrosion mechanisms, time and glass composition dependence.

Catalytic Effect of Nanoparticles on Primary and Secondary Phase Nucleation

2013 ◽  
Vol 765 ◽  
pp. 250-254 ◽  
Author(s):  
Michael P. de Cicco ◽  
John H. Perepezko
Keyword(s):  
Secondary Phase ◽  
Zinc Alloy ◽  
Secondary Phases ◽  
Metal Matrix Nanocomposites ◽  
Secondary Phase Formation ◽  
Droplet Emulsion ◽  
Phase Nucleation ◽  
Equiaxed Grains ◽  
Matrix Nanocomposites ◽  
Primary Aluminium

Nanoparticles were shown to catalyze nucleation of primary and secondary phases in metal matrix nanocomposites (MMNCs). This catalysis is important as it contributes to the mechanical property enhancement in the MMNCs. Primary aluminium grain refinement was demonstrated in A356 matrix nanocomposites. Various types and sizes of nanoparticles (SiC, TiC, γ-Al2O3; 10-96 nm) were used to make these MMNCs and in all cases the MMNCs had smaller, more equiaxed grains compared to the reference A356. Using the droplet emulsion technique, undercoolings were shown to be significantly reduced. Undercoolings in the MMNCs were in good general agreement with the undercooling necessary for free growth, suggesting the applicability of this model to nucleation on nanoscale catalysts. Secondary phase nucleation catalysis was demonstrated in a zinc alloy AC43A MMNC and a binary Mg-4Zn MMNC. In AC43A, secondary phase nucleation was catalyzed with the addition of various nanoparticles (TiC, SiC, γ-Al2O3). The secondary phase nucleation catalysis in AC43A coincided with ductility enhancement. In Mg-4Zn, SiC nanoparticle addition changed the secondary phases that formed. MgZn2 was formed in the MMNC at relatively high temperatures consuming the Zn and reducing the amount of the low temperature Mg2Zn3 phase that formed in the reference alloy. The change in secondary phase formation coincided with significant enhancement in strength and ductility.

The behavior of unirradiated UO2and uraninite under repository conditions characterized by Raman

MRS Advances ◽  
2016 ◽  
Vol 1 (62) ◽  
pp. 4157-4162 ◽  
Author(s):  
L. J. Bonales ◽  
J.M. Elorrieta ◽  
C. Menor-Salván ◽  
J. Cobos
Keyword(s):  
Raman Spectroscopy ◽  
Spent Nuclear Fuel ◽  
Secondary Phase ◽  
Storage Conditions ◽  
Oxidation Products ◽  
Deep Geological Repository ◽  
Secondary Phases ◽  
Secondary Phase Formation ◽  
Geological Repository ◽  
Spectroscopy Studies

ABSTRACTRaman spectroscopy studies have been performed on one hand to identify different materials related to spent nuclear fuel (SNF), and on the other hand to study the behavior of SNF at different storage conditions. Specifically, the expected oxidation of the SNF matrix under dry storage conditions and the formation of secondary phases (SP), as a result of corrosion of SNF in a deep geological repository, have been studied. In order to perform these experiments, two protocols based on the Raman spectroscopy technique have been developed. The results show U4O9/U3O7and U3O8as oxidation products of UO2powder at high temperatures in air, and the secondary phase formation (rutherfordine, UO2(CO3), soddyite, (UO2)2SiO4•2H2O, uranophane alpha Ca(UO2)2(SiO3OH)2•5H2O and kasolite, PbUO2SiO4•H2O), due to uraninite corrosion under the conditions of Sierra Albarrana (Spain).

scholarly journals Waste Glass Corrosion Modeling: Comparison with Experimental Results

1993 ◽  
Vol 333 ◽  
Author(s):  
William. L. Bourcier
Keyword(s):  
Borosilicate Glass ◽  
State Theory ◽  
Secondary Phases ◽  
Path Modeling ◽  
Glass Dissolution ◽  
Glass Corrosion ◽  
Controlling Processes ◽  
Rate Limiting ◽  
Geochemical Reaction

ABSTRACTModels for borosilicate glass dissolution must account for the processes of (1) kinetically-controlled network dissolution, (2) precipitation of secondary phases, (3) ion exchange, (4) rate-limiting diffusive transport of silica through a hydrous surface reaction layer, and (5) specific glass surface interactions with dissolved cations and anions. Current long-term corrosion models for borosilicate glass employ a rate equation consistent with transition state theory embodied in a geochemical reaction-path modeling program that calculates aqueous phase speciation and mineral precipitation/dissolution. These models are currently under development. Future experimental and modeling work to better quantify the rate-controlling processes and validate these models are necessary before the models can be used in repository performance assessment calculations.

scholarly journals The Influence of Long-term Ageing on the Microstructure of Sanicro 25 Steel

2019 ◽  
Vol 253 ◽  
pp. 03004 ◽  
Author(s):  
Marek Sroka ◽  
Adam Zieliński ◽  
Grzegorz Golański ◽  
Marek Kremzer
Keyword(s):  
Secondary Phase ◽  
Laves Phase ◽  
Test Results ◽  
Secondary Phases ◽  
Separation Processes ◽  
Σ Phase ◽  
Initial Stage ◽  
High Efficient ◽  
Secondary Phase Separation

Sanicro 25 (22Cr25NiWCoCu) is a newly developed austenitic stainless steel used in the boiler pressure superheaters and reheaters with ultra-supercritical high-efficient parameters. The paper presents the results of microstructure testing and secondary phase separation processes after 20,000 h ageing at 700 and 750 °C. In the initial stage of ageing, the precipitation of numerous very small M23C6 chromium carbides and Laves phase were observed. The long-term ageing related to temperature revealed the existence of secondary phases: M23C6, MX, NbCrN, Laves phase and σ phase. The test results presented in the paper are part of the developed material characteristics to be used for predicting the service life of the material of components operated under creep conditions.

Sign in / Sign up

Export Citation Format

Share Document