Corrosion Resistance of Ceramic Refractories to Simulated Waste Glasses at High Temperatures

MRS Proceedings ◽

10.1557/proc-412-181 ◽

1995 ◽

Vol 412 ◽

Cited By ~ 1

Author(s):

Shi-Ben Xing ◽

Yijing Lin ◽

Robert K. Mohr ◽

Ian L. Pegg

Keyword(s):

Compositional Analysis ◽

Waste Glass ◽

Refractory Materials ◽

Minor Components ◽

Simulated Waste ◽

Refractory Life ◽

Added Benefit ◽

Higher Temperature ◽

Test Increase ◽

Kinetics Of

AbstractIn many vitrification processes, refractory materials are used to contain the waste glass melt. The corrosive nature of the high-temperature melt consumes the waste feed materials but also limits refractory life. As vitrification is applied to more diverse waste streams, and particularly in higher-temperature applications, increasingly severe demands are placed on the refractory materials. A variety of potential refractory materials including Fused-cast AZS, Monofrax K3, Monofrax E, and the Corhart refractories ER1195, ER2161, C1215, C1215Z, Rechrome, and TI 186, were subjected to corrosion testing at 1450°C using the ASTM C-621 procedure. A series of simulated waste glasses was used which included F, Cl, S, Cu, Zn, Pb; these minor components were found to cause significant, and in some cases drastic, increases in corrosion rates. The corrosion tests were conducted over a range of time intervals extending to 144 hrs in order to investigate the kinetics of the corrosion processes. The change of the concentrations of constituents in the glass was monitored by compositional analysis of glass samples and correlated to the observed extent of corrosion; typically, components of the material under test increase with time while key minor components, such as Cu and Pb, decrease. The rate of corrosion of high-zirconia refractories was slowed considerably by adding zirconia to the waste glass composition; this has the added benefit of improving the aqueous leach resistance of the waste form that is produced.

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Surface Layer Formation on a Nuclear Waste Glass

MRS Proceedings ◽

10.1557/proc-15-37 ◽

1982 ◽

Vol 15 ◽

Cited By ~ 6

Author(s):

Werner Lutze ◽

GÜnter Malow ◽

Harald Rabe ◽

Thomas J. Headley

Keyword(s):

Waste Glass ◽

Layer Formation ◽

Surface Layers ◽

Protective Function ◽

Leach Rate ◽

Simulated Waste ◽

Volcanic Glasses ◽

The Stability ◽

Kinetics Of ◽

Surface Layer Formation

Surface layers are a common feature of leached surfaces of borosilicate waste glasses. Layers are also observed upon weathering of volcanic glasses[l] and of silicate minerals[2]. The question of whether these layers can protect the glass against further attack by decreasing the leach rate is stïll a subject of controversy[3]. Both in geochemical work[4] and in work on waste forms [5,6], surface layers are attributed a protective function, and the stability of leached, million years old volcanic glasses[1] may be due to the presence of palagonite, a thin (≤100 μm) alteration layer, which forms in a few years but does not seem to increase in thickness after this time. The present study investigates the effects of layer formation on leaching kinetics of a borosilicate waste glass containing 20 wt.% LWR-type simulated waste oxides.

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Growth of Surface Layer During the Leaching of The Simulated Waste Glass and its Barrier Effects on the Leaching

MRS Proceedings ◽

10.1557/proc-15-135 ◽

1982 ◽

Vol 15 ◽

Cited By ~ 1

Author(s):

K. Ishiguro ◽

N. Kawanishi ◽

N. Sasaki ◽

H. Nagaki ◽

M. Yamamoto

Keyword(s):

Effective Diffusion ◽

Waste Glass ◽

Transition Elements ◽

Surface Layers ◽

Barrier Effects ◽

Corrosion Kinetics ◽

Layer Structures ◽

Simulated Waste ◽

Different Types ◽

Kinetics Of

ABSTRACTThe growth of surface layers on simulated waste glass during two different types of leaching has been studied in conjunction with their corrosion kinetics. Static and Soxhlet leach tests were performed in distilled water at a temperature of 100°C. Auger and ESCA analyses of solid samples after leaching showed that the layers consisted of two or three sublayers which were distinguished by their different components. The transition elements Fe and Ni, the rare-earths Nd and La, and Zn were concentrated in the layers, while Si, B and alkali were depleted in most of the layers. Growth kinetics of the layers followed approximately linear relations for the two types of leaching. Growth rates and elemental profiles of the layers depended upon the leaching conditions. Comparison between the leaching rate and the thickness of the layer showed that layers did not work as effective diffusion barriers until a threshold thickness was reached, which depended on the layer structures.

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Kinetics of carbon monoxide methanation on a Ni/SiO2 catalyst

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19901678 ◽

1990 ◽

Vol 55 (7) ◽

pp. 1678-1685

Author(s):

Vladimír Stuchlý ◽

Karel Klusáček

Keyword(s):

Carbon Monoxide ◽

Reaction Rate ◽

Catalyst Activity ◽

Adsorbed Hydrogen ◽

Reaction Products ◽

Co Methanation ◽

Molar Ratios ◽

Rate Determining Step ◽

Higher Temperature ◽

Kinetics Of

Kinetics of CO methanation on a commercial Ni/SiO2 catalyst was evaluated at atmospheric pressure, between 528 and 550 K and for hydrogen to carbon monoxide molar ratios ranging from 3 : 1 to 200 : 1. The effect of reaction products on the reaction rate was also examined. Below 550 K, only methane was selectively formed. Above this temperature, the formation of carbon dioxide was also observed. The experimental data could be described by two modified Langmuir-Hinshelwood kinetic models, based on hydrogenation of surface CO by molecularly or by dissociatively adsorbed hydrogen in the rate-determining step. Water reversibly lowered catalyst activity and its effect was more pronounced at higher temperature.

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Pyrolysis and Oxidation of PAN in Dry Air. Thermoanalytical Methods

Materials Science ◽

10.5755/j01.ms.17.1.246 ◽

1970 ◽

Vol 17 (1) ◽

pp. 38-42

Author(s):

Anna BIEDUNKIEWICZ ◽

Pawel FIGIEL ◽

Marta SABARA

Keyword(s):

Temperature Increase ◽

Heating Rates ◽

Linear Change ◽

Dry Air ◽

Isothermal Conditions ◽

Gaseous Products ◽

Heterogeneous Processes ◽

Temperature Ranges ◽

Higher Temperature ◽

Kinetics Of

The results of investigations on pyrolysis and oxidation of pure polyacrylonitrile (PAN) and its mixture with N,N-dimethylformamide (DMF) under non-isothermal conditions at linear change of samples temperature in time are presented. In each case process proceeded in different way. During pyrolysis of pure PAN the material containing mainly the product after PAN cyclization was obtained, while pyrolysis of PAN+DMF mixture gave the product after cyclization and stabilization. Under conditions of measurements, in both temperature ranges, series of gaseous products were formed.For the PAN-DMF system measurements at different samples heating rates were performed. The obtained results were in accordance with the kinetics of heterogeneous processes theory. The process rates in stages increased along with the temperature increase, and TG, DTG and HF function curves were shifted into higher temperature range. This means that the process of pyrolysis and oxidation of PAN in dry air can be carried out in a controlled way.http://dx.doi.org/10.5755/j01.ms.17.1.246

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Effects of Dispersed Al2O3 Particles on Sintering of LTCC

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.39-40.375 ◽

2008 ◽

Vol 39-40 ◽

pp. 375-380

Author(s):

Ralf Müller ◽

Stefan Reinsch ◽

Markus Eberstein ◽

Joachim Deubener ◽

A. Thiel ◽

...

Keyword(s):

Volume Fraction ◽

Al2o3 Particle ◽

Model Composite ◽

Heating Microscopy ◽

Glass Crystal ◽

Rate Controlled ◽

Higher Temperature ◽

Crystal Particle ◽

Kinetics Of ◽

Glass Viscosity

The sintering of Low Temperature Co-fired Ceramics prepared from alumoborosilicate glass- and Al2O3 powders of similar small particle size was studied by dilatometry, heating microscopy, microstructure analysis, glass- and effective viscosity measurements. The steric effect of Al3O3 inclusions was studied using a “non-reactive” model composite. With increasing Al3O3 volume fraction ( Φ ≤ 0.45), sintering decelerates and its final stage shifts to higher temperature. The attainable shrinkage is reduced as Al2O3 particle clusters bearing residual pores become more frequent. The kinetics of sintering could be described formally superposing the weighed contributions of differentially sized and randomly composed glass-crystal particle clusters and assuming a sintering rate controlled by the effective matrix viscosity, which increases with Φ and with progressive wetting of Al2O3 particles during densification. The “reactive” model composite shows significant dissolution of Al2O3 into the glass, which has two opposed effects on sintering: reducing Φ and increasing glass viscosity. For the present case ( Φ = 0.25), the latter effect dominates and sintering is retarded by Al2O3 dissolution. Crystallization of wollastonite starts after full densification. Dissolution of Al2O3 was found to promote the subsequent growth of anorthite.

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Chicken Intestinal Alkaline Phosphatase

The Journal of General Physiology ◽

10.1085/jgp.43.6.1149 ◽

1960 ◽

Vol 43 (6) ◽

pp. 1149-1169 ◽

Cited By ~ 18

Author(s):

M. Kunitz

Keyword(s):

Alkaline Phosphatase ◽

Zinc Ions ◽

Magnesium Ions ◽

Intestinal Alkaline Phosphatase ◽

Reversible Inactivation ◽

Higher Temperature ◽

Kinetics Of ◽

Hydrolysis Of ◽

Zn Ions ◽

Denaturation Of Proteins

Purified chicken intestinal alkaline phosphatase is active at pH 8 to 9, but becomes rapidly inactivated with change of pH to 6 or less. Also, a solution of the inactivated enzyme at pH 4.5 rapidly regains its activity at pH 8. In the range of pH 6 to 8 a solution of purified alkaline phosphatase consists of a mixture of active and inactive enzyme in equilibrium with each other. The rate of inactivation at lower pH and of reactivation at higher pH increases with increase in temperature. Also, the activity at equilibrium in the range of pH 6 to 8 increases with temperature so that a solution equilibrated at higher temperature loses part of its activity on cooling, and vice versa, a rise in temperature shifts the equilibrium toward higher activity. The kinetics of inactivation of the enzyme at lower pH and the reactivation at higher pH is that of a unimolecular reaction. The thermodynamic values for the heat and entropy of the reversible inactivation and reactivation of the enzyme are considerably lower than those observed for the reversible denaturation of proteins. The inactivated enzyme at pH 4 to 6 is rapidly reactivated on addition of Zn ions even at pH 4 to 6. However, zinc ions are unable to replace magnesium ions as cocatalysts for the enzymatic hydrolysis of organic phosphates by alkaline phosphatase.

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The Self-Decay Characteristics of Chlorine Dioxide in Water

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.610-613.296 ◽

2012 ◽

Vol 610-613 ◽

pp. 296-299

Author(s):

Xin Jie Li ◽

Dan Nan Jiang ◽

Yue Jun Zhang

Keyword(s):

Rate Constants ◽

Tap Water ◽

Pure Water ◽

Decay Behaviour ◽

Increase With Increase ◽

Higher Temperature ◽

Effects Of Temperature ◽

Lower Temperature ◽

Kinetics Of ◽

Temperature Water

In order to learn the ClO2 decay behaviour in tap water, the kinetics of ClO2 decay in pure water was studied. Under the conditions of tap water treatment and keeping away from light, the effects of temperature and pH on ClO2 degradation were investigated. The results show that the ClO2 decay reaction in pure water is the first-order with respect to ClO2, the decay rate constants increase with increase in temperature or pH. At pH=6.87, the rate constants are 0.012h-1(15°C), 0.017h-1(25°C), 0.023h-1(35°C), and 0.029h-1(45°C), respectively. At 25°C, the rate constants are 0.0083h-1(pH=4.5), 0.0111h-1(pH=5.5), 0.0143h-1(pH=6.5), 0.0222h-1(pH=7.5), and 0.0351h-1(pH=8.5), respectively. The experimental data prove that ClO2 is more stable in acidic or lower temperature water than in neutral, alkalescent, or higher temperature water.

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The kinetics of comminution of some refractory materials

Soviet Powder Metallurgy and Metal Ceramics ◽

10.1007/bf01111819 ◽

1964 ◽

Vol 2 (2) ◽

pp. 95-98 ◽

Cited By ~ 1

Author(s):

A. I. Avgustinik ◽

V. Sh. Vigdergauz ◽

V. M. Gropyanov ◽

G. V. Drozdetskaya

Keyword(s):

Refractory Materials ◽

Kinetics Of

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The initial dissolution rates of simulated UK Magnox–ThORP blend nuclear waste glass as a function of pH, temperature and waste loading

Mineralogical Magazine ◽

10.1180/minmag.2015.079.6.28 ◽

2015 ◽

Vol 79 (6) ◽

pp. 1529-1542 ◽

Cited By ~ 14

Author(s):

N. Cassingham ◽

C.L. Corkhill ◽

D.J. Backhouse ◽

R.J. Hand ◽

J.V. Ryan ◽

...

Keyword(s):

Dissolution Kinetics ◽

Intrinsic Rate ◽

Waste Glass ◽

High Level Waste ◽

Dissolution Mechanism ◽

Dissolution Rates ◽

Forward Rates ◽

Glass Dissolution ◽

High Level ◽

Kinetics Of

AbstractThe first comprehensive assessment of the dissolution kinetics of simulant Magnox–ThORP blended UK high-level waste glass, obtained by performing a range of single-pass flow-through experiments, is reported here. Inherent forward rates of glass dissolution were determined over a temperature range of 23 to 70°C and an alkaline pH range of 8.0 to 12.0. Linear regression techniques were applied to the TST kinetic rate law to obtain fundamental parameters necessary to model the dissolution kinetics of UK high-level waste glass (the activation energy (Ea), pH power law coefficient (η) and the intrinsic rate constant (k0)), which is of importance to the post-closure safety case for the geological disposal of vitreous products. The activation energies based on B release ranged from 55 ± 3 to 83 ± 9 kJ mol–1, indicating that Magnox–THORP blend glass dissolution has a surface-controlled mechanism, similar to that of other high-level waste simulant glass compositions such as the French SON68 and LAW in the US. Forward dissolution rates, based on Si, B and Na release, suggested that the dissolution mechanism under dilute conditions, and pH and temperature ranges of this study, was not sensitive to composition as defined by HLW-incorporation rate.

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