scholarly journals Experimental investigation and computer simulation of diffusion in Pt-coated bulk Ni

2010 ◽  
Vol 46 (2) ◽  
pp. 153-160 ◽  
Author(s):  
W. Gong ◽  
L. Zhang ◽  
M. Ode ◽  
H. Murakami ◽  
C. Zhou
Keyword(s):  
Thin Film ◽  
Experimental Investigation ◽  
Electron Probe ◽  
Bulk Diffusion ◽  
Concentration Profiles ◽  
Atomic Mobility ◽  
Measured Concentration ◽  
Calculated Concentration ◽  
Higher Temperature ◽  
Interdiffusion Coefficients

The concentration profiles of thin-film Pt/bulk Ni coatings annealed at 1150, 1250 and 1300?C for different time were measured by means of electron probe microanalysis. The corresponding interdiffusion coefficients were then determined using the thin-film solution. The calculated concentration profiles based on the presently obtained interdiffusion coefficients agree well with the experimental ones, but better at a higher temperature or a longer time. The comparison between the presently measured concentration profiles and the DICTRA simulated ones indicates that it is promising to apply the well-established atomic mobility databases due to bulk diffusion information in coating systems with some simple modifications for diffusivities.

scholarly journals Calculated interdiffusivities resulting from different fitting functions applied to measured concentration profiles in Cu-rich fcc Cu-Ni-Sn alloys at 1073 K

2017 ◽  
Vol 53 (3) ◽  
pp. 255-262 ◽  
Author(s):  
Y. Liu ◽  
D. Liu ◽  
Y. Du ◽  
S. Liu ◽  
D. Kuang ◽  
...  
Keyword(s):  
Error Propagation ◽  
Scientific Method ◽  
Electron Probe ◽  
Bulk Diffusion ◽  
Ternary Systems ◽  
Concentration Profiles ◽  
Diffusion Couples ◽  
Green Method ◽  
Measured Concentration ◽  
Interdiffusion Coefficients

Employing six groups of bulk diffusion couples together with electron probe microanalysis technique, the compositiondependences of ternary interdiffusion coefficients in Cu-rich fcc Cu-Ni-Sn alloys at 1073 K were determined via the Whittle and Green method. Different fitting functions applied to the measured concentration profiles are utilized to extract the interdiffusion coefficients of fcc Cu-Ni-Sn alloys. The errors for the obtained interdiffusivities are evaluated by a scientific method considering the error propagation. The calculated diffusion coefficients using the Boltzmann and additive Boltzmann functions are found to be with reasonable errors and show a general agreement with those using other fitting functions. Based on the Boltzmann and additive Boltzmann functions, the interdiffusivities in Cu-rich fcc Cu-Ni-Sn alloys at 1073 K are obtained and validated by thermodynamic constraints. The Boltzmann and additive Boltzmann functions are recommended to be used for the fitting of measured concentration profiles in other ternary systems for the sake of extracting ternary diffusivities.

Prediction of the Depletion Zone due to Selective Oxidation of P91 Steel

2005 ◽  
Vol 237-240 ◽  
pp. 965-970 ◽  
Author(s):  
Marek Danielewski ◽  
Robert Filipek ◽  
Barbara Kucharska
Keyword(s):  
Selective Oxidation ◽  
Computer Modelling ◽  
Average Concentration ◽  
Concentration Profiles ◽  
Unique Determination ◽  
Measured Concentration ◽  
P91 Steel ◽  
Calculated Concentration ◽  
Key Factor ◽  
Limitation Method

Experimental measurements do not allow for a unique determination of the concentration profiles, e.g., in case of multi-layer systems. The measured concentration of the elements at the alloy/scale interface is an average concentration in an alloy and in a scale near the spot of the beam [1]. The knowledge of the concentration of the elements at the boundary is necessary for the understanding corrosion of alloys. This essential obstacle of experimental techniques can be overcome by computer modelling. Namely, by combining the different methods (non-unique measurement with unique modelling). The Danielewski-Holly model of interdiffusion has a unique solution. This model enables to predict the evolution of component distributions in the reacting alloy. The model is valid for time dependent boundary conditions and consequently can be used for modelling the more complex reactions, eg., the formation of complex oxides. To avoid the nonphysical values of fluxes in reacting alloy the kinetic constraint on all fluxes was introduced, i.e., the flux limitation method. The results of the selective oxidation of the P91 steel (0,1 wt.% C, 8,6 wt.% Cr, 0,25 wt.% Ni) are presented. Calculated concentration profiles are compared with the experimental data. We show the evolution of chromium distribution in oxidizing steel up to 3 000 hours. The computations demonstrate that chromium depletion is the key factor determining the scale composition.

Ternary and Quaternary Interdiffusion in γ (fcc) Fe-Ni-Cr-X (X = Si, Ge) Alloys at 900°C

2008 ◽  
Vol 595-598 ◽  
pp. 1145-1152 ◽  
Author(s):  
N. Garimella ◽  
M.P. Brady ◽  
Yong Ho Sohn
Keyword(s):  
Cross Sections ◽  
Electron Probe ◽  
Concentration Profiles ◽  
Diffusion Couples ◽  
Alloying Additions ◽  
Cr2o3 Scale ◽  
Interdiffusion Flux ◽  
Solid Diffusion ◽  
Interdiffusion Coefficients ◽  
And Diffusion

Interdiffusion in Fe-Ni-Cr (fcc γ phase) alloys with small additions of Si and Ge at 900°C was studied using solid-to-solid diffusion couples. Alloy rods of Fe-24 at.%Ni, Fe-24 at.%Ni- 22at.%Cr, Fe-24 at.%Ni-22at.%Cr-4at.%Si and Fe-24 at.%Ni-22at.%Cr-1.7at.%Ge were cast using arc-melt, and homogenized at 900°C for 168 hours. Sectioned alloy disks from the rods were polished, and diffusion couples were assembled with in Invar steel jig, encapsulated in Argon after several hydrogen flushes, and annealed atz 900°C for 168 hours. Polished cross-sections of the diffusion couples were characterized to determine experimental concentration profiles using electron probe microanalysis with pure elemental standards. Interdiffusion fluxes of individual components were calculated directly from the experimental concentration profiles, and the moments of interdiffusion flux profiles were examined to determine the average ternary and quaternary interdiffusion coefficients. Effects of alloying additions on the interdiffusional behavior of Fe-Ni- Cr-X alloys at 900°C are presented with due consideration for the formation of protective Cr2O3 scale.

Interdiffusion in (fcc) Ni-Cr-X (X = Al, Si, Ge or Pd) Alloys at 700°C

2007 ◽  
Vol 266 ◽  
pp. 191-198 ◽  
Author(s):  
N. Garimella ◽  
M.P. Brady ◽  
Yong Ho Sohn
Keyword(s):  
Cross Sections ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Concentration Profiles ◽  
Diffusion Couples ◽  
Alloying Additions ◽  
Cr2o3 Scale ◽  
Solid Diffusion ◽  
Ternary Alloying ◽  
Interdiffusion Coefficients

Interdiffusion at 700°C for Ni-22at.%Cr (fcc γ phase) alloys with small additions of Al, Si, Ge, or Pd was examined using solid-to-solid diffusion couples. Rods of Ni-22at.%Cr, Ni- 21at.%Cr-6.2at.%Al, Ni-22at.%Cr-4.0at.%Si, Ni-22at.%Cr-1.6at.%Ge and Ni-22at.%Cr-1.6at.%Pd alloys were cast using arc-melt and homogenized at 900°C for 168 hours. The diffusion couples were assembled with alloy disks in Invar steel jig, encapsulated in Argon after several hydrogen flushes, and annealed at 700°C for 720 hours. Experimental concentration profiles were determined from polished cross-sections by using electron probe microanalysis with pure standards of Ni, Cr, Al, Si, Ge and Pd. Interdiffusion fluxes of individual components were calculated directly from the experimental concentration profiles, and the moments of interdiffusion fluxes were examined to determine average ternary interdiffusion coefficients. Effects of ternary alloying additions on the interdiffusional behavior of Ni-Cr-X alloys at 700°C are presented in the light of the diffusional interactions and the formation of protective Cr2O3 scale.

Study on Atomic Mobility and Molar Volume for FCC Fe-Co Phase

2014 ◽  
Vol 936 ◽  
pp. 1201-1208 ◽  
Author(s):  
Xiu Mian Gong ◽  
Xiao Gang Lu ◽  
Yan Lin He
Keyword(s):  
Molar Volume ◽  
Diffusion Coefficients ◽  
Electron Probe ◽  
Lattice Parameter ◽  
Measured Data ◽  
Atomic Mobility ◽  
Electron Probe Micro Analysis ◽  
Micro Analysis ◽  
Interdiffusion Coefficients ◽  
Diffusion Profiles

The diffusion-couple experiments have been performed at 1273 K and 1423 K in order to verify and bias the controversial interdiffusion data in the literature. In the meantime, the literature data on the lattice parameter have been assessed to obtain the molar volume of fcc Fe-Co phase, which was in turn fed into the Sauer-Freise equation to retrieve the interdiffusion coefficients from the EPMA (Electron Probe Micro-Analysis) measured diffusion profiles. The reliable experimental data on the diffusion coefficients for fcc Fe-Co phase have finally been used to assess the atomic mobility. A general agreement has been reached between the calculated and experimentally measured data.

Application Of Electron Probe Analyses Of Minerals In Discussing The Relationship Between Ductile Deformation And Metamorphism

1990 ◽  
Vol 48 (2) ◽  
pp. 250-251
Author(s):  
Fan Guochuan ◽  
Sun Zhongshi
Keyword(s):  
Chemical Composition ◽  
Shear Deformation ◽  
Electron Probe ◽  
General Rule ◽  
Granulite Facies ◽  
Ductile Deformation ◽  
Higher Temperature ◽  
Ductile Shear ◽  
The Relationship ◽  
Ductile Shear Deformation

Under influence of ductile shear deformation, granulite facies mineral paragenesis underwent metamorphism and changes in chemical composition. The present paper discusses some changes in chemical composition of garnet in hypers thene_absent felsic gnesiss and of hypersthene in rock in early and late granulite facies undergone increasing ductile shear deformation .In garnet fetsic geniss, band structures were formed because of partial melting and resulted in zoning from massive⟶transitional⟶melanocrate zones in increasing deformed sequence. The electron-probe analyses for garnet in these zones are listed in table 1 . The Table shows that Mno, Cao contents in garnet decrease swiftly from slightly to intensely deformed zones.In slightly and moderately deformed zones, Mgo contents keep unchanged and Feo is slightly lower. In intensely deformed zone, Mgo contents increase, indicating a higher temperature. This is in accord with the general rule that Mgo contents in garnet increase with rising temperature.

Effects of Rotation on Blade Surface Heat Transfer: An Experimental Investigation

1997 ◽  
Author(s):  
Roger W. Moss ◽  
Roger W. Ainsworth ◽  
Tom Garside
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Experimental Investigation ◽  
Turbine Blade ◽  
Time History ◽  
Surface Heat ◽  
Blade Surface ◽  
Surface Heat Transfer ◽  
Effects Of Rotation ◽  
Wake Passing

Measurements of turbine blade surface heat transfer in a transient rotor facility are compared with predictions and equivalent cascade data. The rotating measurements involved both forwards and reverse rotation (wake free) experiments. The use of thin-film gauges in the Oxford Rotor Facility provides both time-mean heat transfer levels and the unsteady time history. The time-mean level is not significantly affected by turbulence in the wake; this contrasts with the cascade response to freestream turbulence and simulated wake passing. Heat transfer predictions show the extent to which such phenomena are successfully modelled by a time-steady code. The accurate prediction of transition is seen to be crucial if useful predictions are to be obtained.

Validation of a Two-Pool Model for the Kinetics of ß2-Microglobulin

2002 ◽  
Vol 25 (5) ◽  
pp. 411-420 ◽  
Author(s):  
S. Stiller ◽  
X.Q. Xu ◽  
N. Gruner ◽  
J. Vienken ◽  
H. Mann
Keyword(s):  
Standard Deviation ◽  
Plasma Concentrations ◽  
Generation Rate ◽  
Secondary Amyloidosis ◽  
Concentration Profiles ◽  
Dialysis Dose ◽  
Measured Concentration ◽  
Pool Model ◽  
Efficacy Parameters ◽  
Beta 2 Microglobulin

Secondary amyloidosis due to beta-2-microglobulin (ß2-m) is a serious long-term complication in patients on regular dialysis therapy. ß2-m can be considered a middle-molecule marker used to facilitate the assessment of dialysis efficacy. For this purpose, a validated model that calculates characteristic efficacy parameters, such as Kt/V, TAC and generation rate, is needed. There is general agreement that ß2-m-kinetics should be described by a two-pool model, but little has been published to validate such an approach. We measured the ß2-m concentration profiles of eight stable patients during hemodialysis (HD) at the start of treatment, after 30 minutes, after 60 minutes, and every hour until the end. Thereafter they were measured at 10-minute intervals for an hour. The dialyser clearances were determined from the plasma concentrations in front of and behind the dialyser twice during each session – after 1 hour, and 4 hours from the start of treatment. The kinetic parameters of a two-pool model (e.g. the compartment volumes V1 and V2, the mass transfer coefficient K12 and the generation rate G) were determined from the optimal fit of the measured concentration profile. The table below summarises the results by giving the mean and standard deviation for each parameter: V (liters) V1/V2 V % TBW K12 m(ml/min) G (mg/kg/day) 10.0 ± 1.6 4.60 ± 1.8 28.4 ± 3.1 56.3 ± 25.2 2.50 ± 0.66 Inter-individual differences in V1/V2 and K12 were high, ranging from 2.5 to 10.0 for V1/V2 and from 26 to 140 for K12. Error analysis suggested that these wide ranges were due to the method and that in reality the probable range of V is 25–36% of TBW, of V1/V2 3.5–5.3, and of K12 30–80 ml/min. With standard values for these three parameters (V = 30% of TBW, V1/V2 = 4.4 and K12 = 55 ml/m), equal for all patients, and their respective ranges, Kt/V can be calculated with a standard deviation of 13%. Kt/V > 1.2 secures the maximum possible ß2-m removal with three HD treatments a week. Conclusions The parameters of a two-pool model of ß2-m kinetics can be derived from concentration profiles obtained under routine dialysis conditions, but accuracy is not completely satisfactory. Similar to the dialysis dose for urea (Kt/Vurea) the dialysis dose for ß2-m (Kt/Vß2-m) can be calculated from the pre- and post-dialysis concentrations of ß2-m, body weight, ultrafiltration and dialysis time. Kt/Vß2-m > 1.2 secures the maximum possible removal of ß2-m in HD with three sessions per week.

scholarly journals MEASUREMENT OF SEDIMENT SUSPENSION IN COMBINATIONS OF WAVES AND CURRENTS

1972 ◽  
Vol 1 (13) ◽  
pp. 55
Author(s):  
J. Kirkegarrd Jensen ◽  
Torben Sorenson
Keyword(s):  
Thin Layer ◽  
Concentration Profile ◽  
Field Data ◽  
Concentration Profiles ◽  
Sediment Suspension ◽  
Calculated Concentration ◽  
Waves And Currents ◽  
The Mean ◽  
Mean Concentration ◽  
Good Agreement

The paper describes a procedure for obtaining field data on the mean concentration of sediments in combination of waves and currents outside the breaker zone, as well as some results of such measurements. It is assumed that the current turbulence alone is responsible for the maintenance of the concentration profile above a thin layer close to the bottom, in which pick-up of sediments due to wave agitation takes place. This assumption gives a good agreement between field data and calculated concentration profiles.

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