Kinetics of Phosphorus Segregation in the Grain Boundaries of VVER-1000 Pressure Vessel Steels

2017 ◽  
Vol 375 ◽  
pp. 125-133 ◽  
Author(s):  
Boris Bokstein ◽  
Anatole N. Khodan ◽  
Mikhail V. Sorokin ◽  
Alexey O. Rodin ◽  
Evgeny A. Syutkin ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Auger Analysis ◽  
Phosphorus Segregation ◽  
Quantitative Measurements ◽  
Brittle Fractures ◽  
Fast Transport ◽  
Grain Bulk ◽  
Kinetics Of ◽  
Good Agreement

Methods of AES quantitative analysis were developed and applied for the determination of element concentrations at the surfaces of brittle fractures along grain boundaries. An attempt was made to take into account the presence of carbide precipitates and cleavage areas in the zone of the Auger analysis of their impact on the results of quantitative measurements. Obtained data were used for evaluation of the phosphorous segregation kinetics. The obtained results are consistent with thermodynamic modeling with CALPHAD method.Kinetics of segregation is analyzed with three models: (1) Langmuir - McLean theory; (2) model akin to kinetics of first order chemical reactions in solids; and (3) the model, which takes into account contribution of fast transport within subgrain networks and slow diffusion through the grain bulk. The two later models are in a good agreement with the experimental results.

scholarly journals Single-sided NMR for the measurement of the degree of cross-linking and curing

2018 ◽  
Vol 7 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Norbert Halmen ◽  
Christoph Kugler ◽  
Eduard Kraus ◽  
Benjamin Baudrit ◽  
Thomas Hochrein ◽  
...  
Keyword(s):  
Relaxation Times ◽  
Curing Kinetics ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
First Results ◽  
Non Destructive ◽  
Kinetics Of ◽  
Good Agreement

Abstract. The degree of cross-linking and curing is one of the most important values concerning the quality of cross-linked polyethylene (PE-X) and the functionality of adhesives and resin-based components. Up to now, the measurement of this property has mostly been time-consuming and usually destructive. Within the shown work the feasibility of single-sided nuclear magnetic resonance (NMR) for the non-destructive determination of the degree of cross-linking and curing as process monitoring was investigated. First results indicate the possibility of distinguishing between PE-X samples with different degrees of cross-linking. The homogeneity of the samples and the curing kinetics of adhesives can also be monitored. The measurements show good agreement with reference tests (wet chemical analysis, differential scanning calorimetry, dielectric analysis). Furthermore, the influence of sample temperature on the characteristic relaxation times can be observed.

Effect of C and Ge Concentration On The Thermal Stability of RTCVD Grown Si1-x-yGexCy Alloys

1997 ◽  
Vol 470 ◽  
Author(s):  
Patricia Warren ◽  
Stephane Retzmanick ◽  
Martin Gotza ◽  
Marc Begems
Keyword(s):  
Lattice Constant ◽  
Strain Relaxation ◽  
Mechanical Strain ◽  
Chemical Vapor ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Cubic Silicon Carbide ◽  
Kinetics Of ◽  
Good Agreement

ABSTRACTSi / Si1-x-yGexCy / Si heterostructures containing up to 17 at.% Ge and 1.9 at.% C were grown on (001) silicon by low pressure Rapid Thermal Chemical Vapor Deposition, using a mixture of silane, germane and methylsilane, diluted in hydrogen. The samples were then annealed in a Rapid Thermal Processing furnace, under an atmospheric pressure of nitrogen, at temperatures ranging from 900 to 1130 °C.The samples were characterized using infrared spectroscopy and x-ray diffraction. SIMS profiling and TEM observation were performed on some of the samples.Substitutional C gradually disappeared, either precipitating out to form cubic silicon carbide (β-SiC), or simply vanishing into interstitial positions. In any case, the in-plane lattice constant remained constant after annealing, indicating that there was no mechanical strain relaxation by formation of misfit dislocations. The perpendicular lattice constant increased due to the decrease in substitutional C concentration, as well as it decreased due to the germanium out-diffusion. This variation of the strain during annealing was modeled, and allowed the determination of the kinetics of the substitutional carbon disappearance. The same behavior was observed for all samples. Indeed, the Cs disappearance rate was always increased for samples with higher initial Ge and C concentrations. The kinetics of this precipitation was found in very good agreement with previous published results.

Thermodynamics and Kinetics of Crystallization of Amorphous Si and Ge Produced by Ion Implantation

1983 ◽  
Vol 27 ◽  
Author(s):  
E.P. Donovan ◽  
F. Spaepen ◽  
D. Turnbull ◽  
J.M. Poate ◽  
D.C. Jacobson
Keyword(s):  
Noble Gas ◽  
Amorphous State ◽  
Heat Evolution ◽  
Precise Determination ◽  
Total Enthalpy ◽  
Kinetics Of Crystallization ◽  
Amorphous Si ◽  
Kinetics Of ◽  
Good Agreement

ABSTRACTAmorphous Si and Ge layers, produced by noble gas (Ar or Xe) implantation of single crystal substrates, have been crystallized in a differential scanning calorimeter (DSC). This technique allows determination of the growth velocity (which is proportional to the rate of heat evolution, ΔHac), and the total enthalpy of crystallization ΔHacAmorphous Ge was found to relax continuously to an amorphous state of lower free energy, with a total enthalpy of relaxation of 6.0 kJ.mole−1 before crystallization started. The regrowth velocity on (100) substrates,measured to be 4.2×1017 exp (−2.17eV/kT)Å/sec, is compared to other determinations. The value of ΔHac was found to be 11.66± 0.7 kJ.mole, in good agreement with ΔHac for amorphous Ge produced by other methods. For Si, ΔHac was determined to be 11.95± 0.7 kJ.mole without any evidence of heat release due to relaxation. The kinetics of crystallization measured by DSC are compared with those determined by other techniques. The effects of the implant profile on the regrowth velocity could also be observed directly in the DSC signal. The more accurate value of ΔHac allowed a more precise determination of the melting temperature of amorphous Si: Taℓ= 1420K.

Effect of subgrain structure on the kinetics of phosphorus segregation in grain boundaries

2015 ◽  
Vol 158 ◽  
pp. 151-154 ◽  
Author(s):  
M.V. Sorokin ◽  
Z.V. Lavrukhina ◽  
A.N. Khodan ◽  
D.A. Maltsev ◽  
B.S. Bokstein ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Subgrain Structure ◽  
Phosphorus Segregation ◽  
Kinetics Of

Kinetics of phosphorus segregation at grain boundaries of low-alloy low-carbon steel

2014 ◽  
Vol 115 (2) ◽  
pp. 146-156 ◽  
Author(s):  
B. S. Bokshtein ◽  
A. N. Khodan ◽  
O. O. Zabusov ◽  
D. A. Mal’tsev ◽  
B. A. Gurovich
Keyword(s):  
Carbon Steel ◽  
Grain Boundaries ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Phosphorus Segregation ◽  
Kinetics Of

scholarly journals Spectrofluorometric Determination of Olanzapine and Fluphenazine Hydrochloride in Pharmaceutical Preparations and Human Plasma Using Eosin: Application to Stability Studies

2008 ◽  
Vol 91 (6) ◽  
pp. 1309-1317 ◽  
Author(s):  
Fathalla Belal ◽  
Amina El-Brashy ◽  
Nahed El-Enany ◽  
Nihal El-Bahay
Keyword(s):  
Human Plasma ◽  
Reaction Pathway ◽  
Pharmaceutical Preparations ◽  
Stability Studies ◽  
Quenching Effect ◽  
Spectrofluorometric Determination ◽  
The Mean ◽  
Kinetics Of ◽  
Good Agreement

Abstract A simple, rapid, and sensitive spectrofluorometric method has been developed for the determination of olanzapine (OLZ) and fluphenazine hydrochloride (FPZ HCl). The proposed method is based on the quantitative quenching effect of the studied drugs on the native fluorescence of eosin at pH 3.4 and 3.2 for OLZ and FPZ HCl, respectively. The fluorescence was measured at 547 nm after excitation at 323 nm. The fluorescence-concentration plots were rectilinear over the range of 0.051.0 and 0.101.0 g/mL, with lower detection limits of 1.8 103 and 1.2 103 g/mL, for OLZ and FPZ HCl, respectively. The proposed method was successfully applied to the analysis of commercial tablets and ampules containing the drugs, and the results were in good agreement with those obtained with reference methods. The proposed method was further applied to the determination of OLZ in spiked human plasma. The mean recovery was 98.62 0.24 (n 4). The method was also used for stability studies of FPZ HCl upon oxidation with hydrogen peroxide, and the kinetics of the reaction were studied. A proposal for the reaction pathway was postulated.

scholarly journals Absolute and empirical determination of the enzymatic activity and kinetic investigation of the action of hyaluronidase on hyaluronan using viscosimetry

1995 ◽  
Vol 306 (1) ◽  
pp. 153-160 ◽  
Author(s):  
K P Vercruysse ◽  
A R Lauwers ◽  
J M Demeester
Keyword(s):  
Empirical Relationship ◽  
Gel Permeation Chromatography ◽  
Dilution Method ◽  
Empirical Estimation ◽  
Chromatography Analysis ◽  
Rate Of Reaction ◽  
Kinetics Of ◽  
Empirical Approaches ◽  
Good Agreement

We describe an investigation of the action of hyaluronidase on hyaluronan using viscosimetry. A new viscosimetric approach was developed for determining the activity of the enzyme in katal units. This approach requires knowledge of several parameters (e.g. Mark-Houwink constants) which were determined by combining viscosimetric measurement and gel-permeation chromatography analysis. Using all the necessary parameters we determined the kinetic parameters of the enzyme and found that 250 i.u. correspond to 1 nkat. An empirical viscometric was used to estimate the activity of the enzyme, and the Km was determined using the kinetic dilution method. The estimates produced by the absolute and empirical approaches were in good agreement. We demonstrate that the empirical estimation of the reaction rate is related to the rate of reaction expressed in absolute units and thus provides a good estimate of enzyme activity. Furthermore, we have found an empirical relationship which enables investigation of the kinetics of the enzyme in a simple and sensitive way by viscosimetry.

Determination of the lattice translation across {110} APBs in GaAs

1988 ◽  
Vol 46 ◽  
pp. 600-601
Author(s):  
D.R. Rasmussen ◽  
N.-H. Cho ◽  
C.B. Carter
Keyword(s):  
Grain Boundaries ◽  
Lower Energy ◽  
Antiphase Boundary ◽  
The Other ◽  
Boundary Structure ◽  
Interface Plane ◽  
Inversion Symmetry ◽  
High Angle ◽  
Equilibrium Distance

Domains in GaAs can exist which are related to one another by the inversion symmetry, i.e., the sites of gallium and arsenic in one domain are interchanged in the other domain. The boundary between these two different domains is known as an antiphase boundary [1], In the terminology used to describe grain boundaries, the grains on either side of this boundary can be regarded as being Σ=1-related. For the {110} interface plane, in particular, there are equal numbers of GaGa and As-As anti-site bonds across the interface. The equilibrium distance between two atoms of the same kind crossing the boundary is expected to be different from the length of normal GaAs bonds in the bulk. Therefore, the relative position of each grain on either side of an APB may be translated such that the boundary can have a lower energy situation. This translation does not affect the perfect Σ=1 coincidence site relationship. Such a lattice translation is expected for all high-angle grain boundaries as a way of relaxation of the boundary structure.

Surface reconstructions of (001) cleaved GdBa2Cu3O7-δ

1992 ◽  
Vol 50 (1) ◽  
pp. 106-107
Author(s):  
H.W. Zandbergen ◽  
M.R. McCartney
Keyword(s):  
Electron Microscopy ◽  
Copper Oxide ◽  
Grain Boundaries ◽  
Atomic Structure ◽  
Oxygen Deficiency ◽  
Surface Layers ◽  
Layer Sequence ◽  
Surface Reconstructions ◽  
Good Agreement

Very few electron microscopy papers have been published on the atomic structure of the copper oxide based superconductor surfaces. Zandbergen et al. have reported that the surface of YBa2Cu3O7-δ was such that the terminating layer sequence is bulk-Y-CuO2-BaO-CuO-BaO, whereas the interruption at the grain boundaries is bulk-Y-CuO2-BaO-CuO. Bursill et al. reported that HREM images of the termination at the surface are in good agreement with calculated images with the same layer sequence as observed by Zandbergen et al. but with some oxygen deficiency in the two surface layers. In both studies only one or a few surfaces were studied.

COMPARATIVE ACTION OF VARIOUS OESTROGENIC COMPOUNDS ON MOUSE VAGINAL SIALIC ACIDS (II)

1969 ◽  
Vol 62 (4) ◽  
pp. 663-670 ◽  
Author(s):  
Lars Carlborg
Keyword(s):  
Sialic Acid ◽  
Response Curve ◽  
Sialic Acids ◽  
Clear Cut ◽  
Suitable Parameter ◽  
Sufficient Degree ◽  
Comparative Action ◽  
Relative Potencies ◽  
Good Agreement

ABSTRACT Oestrogens administered in lower doses than necessary to induce full cornification of the mouse vagina induce mucification. It was shown previously that the degree of mucification could be estimated by quantitative determination of sialic acids. A suitable parameter for oestrogen assay was the measurement of vaginal sialic acid concentration which exhibited a clear cut dose response curve. Eleven assays of various oestrogens were performed with this method. Their estimated relative potencies were in good agreement with other routine oestrogen assays. A statistically sufficient degree of precision was found. The sensitivity was of the same order, or slightly higher, than the Allen-Doisy test.

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