Computer simulation of boronizing kinetics for a TB2 alloy

2021 ◽  
Vol 63 (12) ◽  
pp. 1130-1135
Author(s):  
Brahim Boumaali ◽  
Zahra Nait Abdellah ◽  
Mourad Keddam
Keyword(s):  
Diffusion Coefficients ◽  
Integral Method ◽  
Experimental Validation ◽  
Boron Content ◽  
Differential Algebraic Equations ◽  
Algebraic Equations ◽  
Boron Diffusion ◽  
The Mean ◽  
Predicted Values ◽  
Experimental Values

Abstract The boron diffusion at the surface of a TB2 alloy was simulated via two mathematical models relying on the numerical resolutions of the system of differential algebraic equations (DAE) for the integral method and ordinary differential equations for the mean diffusion coefficient (MDC) method. Both approaches allowed us to compute the boron diffusion coefficients in TiB2 and TiB for a maximum boron content of 31.10 wt.-% in TiB2 at 1223, 1273, 1323 and 1373 K. The boron activation energies in TiB2 and TiB were evaluated and compared with the data published in the literature. Finally, an experimental validation of both models was made through a comparison of the thicknesses of the experimental layers with the predicted values. Consequently, the simulated thicknesses were in line with the experimental values.

scholarly journals Analysis of the growth kinetics of Fe2B layers by the integral method

2018 ◽  
Vol 54 (3) ◽  
pp. 361-367 ◽  
Author(s):  
M. Keddam ◽  
M. Kulka
Keyword(s):  
Diffusion Coefficients ◽  
Integral Method ◽  
Present Model ◽  
Armco Iron ◽  
Differential Algebraic Equations ◽  
Algebraic Equations ◽  
Boron Diffusion ◽  
Alternative Approach ◽  
Kinetics Of ◽  
Good Agreement

In this study, an alternative approach based on the integral method was proposed to estimate the values of boron diffusion coefficients in the Fe2B layers grown at the surface of Armco iron. The set of differential algebraic equations (DAE) system was obtained to estimate the value of activation energy for boron diffusion when pack-boriding of Armco iron in the range of 1123 to 1273 K taking into account the boride incubation time. The present model has been validated by making a comparison between the experimental value of Fe2B layer thickness obtained at 1253 K for 5 h and the predicted results by using two different approaches. A good agreement was observed between these two set of data.

Characterization and boriding kinetics of AISI T1 steel

2018 ◽  
Vol 116 (1) ◽  
pp. 102 ◽  
Author(s):  
Martin Ortiz-Domínguez ◽  
Mourad Keddam ◽  
Milton Elias-Espinosa ◽  
Marius Ramírez-Cardona ◽  
Alberto Arenas-Flores ◽  
...  
Keyword(s):  
Boride Layer ◽  
Differential Algebraic Equations ◽  
Wear Behaviour ◽  
Algebraic Equations ◽  
Boron Diffusion ◽  
Time Duration ◽  
Pin On Disc ◽  
Predicted Values ◽  
Boriding Process ◽  
Scratch Tests

The AISI T1 steel was hardened by the solid boriding process in the temperature range 1123–1273 K for a time duration of 2 to 8 h. A kinetic model, based on the integral method, was applied to the growth of a single boride layer (Fe2B) at the surface of AISI T1 steel. This diffusion model has been validated experimentally by considering two additional boriding conditions. A numerical solution was then obtained after solving the set of differential algebraic equations in order to compare the experimental thicknesses of Fe2B layers with the predicted values. The activation energy for boron diffusion in AISI T1 steel was estimated as 212.76 kJ mol−1and a comparison was made with other values available in the literature. The formed boride layers with a saw-tooth morphology were examined by scanning electron microscopy (SEM). X-ray diffraction confirmed that the borided layer was composed of only Fe2B. The Daimler-Benz Rockwell-C indentation technique was employed to assess the cohesion of Fe2B layers on AISI T1 steel. In addition, the pin-on-disc and wear scratch tests were carried out for investigating the wear behaviour of borided AISI T1 steel.

scholarly journals Simulating the Growth of Dual-Phase Boride Layer on AISI M2 Steel by Two Kinetic Approaches

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 433
Author(s):  
Mourad Keddam ◽  
Peter Jurči
Keyword(s):  
Integral Method ◽  
Activation Energies ◽  
Boride Layer ◽  
Differential Algebraic Equations ◽  
Dual Phase ◽  
Algebraic Equations ◽  
Incubation Periods ◽  
Experimental Values ◽  
Kinetics Of

Two kinetic approaches (integral method and Dybkov method) have been applied for simulating the boriding kinetics of AISI M2 steel in the range of 1173 to 1323 K, by including the effect of incubation periods. For the integral method, a peculiar solution of the resulting system of differential algebraic equations (DAE) has been employed for assessing the diffusivities of boron in FeB and Fe2B. The boron activation energies in FeB and Fe2B have been deduced from both approaches and compared with the data taken from the literature. Furthermore, to experimentally extend the validity of both approaches, four additional boriding conditions obtained on the boronized samples at 1173, 1223, 1273 and 1323 K for 10 h were then used. The predicted boride layers’ thicknesses were confronted to the experimental values. Consequently, a satisfactory concordance was obtained when comparing the simulated layers’ thicknesses to the experimental values derived from the literature.

scholarly journals Simulation of boronizing kinetics of ASTM A36 steel with the alternative kinetic model and the integral method

2021 ◽  
Vol 65 (1) ◽  
pp. 33-39
Author(s):  
Z. Nait Abdellah ◽  
M. Keddam ◽  
P. Jurči
Keyword(s):  
Activation Energy ◽  
Layer Thickness ◽  
Integral Method ◽  
Experimental Validation ◽  
Mass Balance Equation ◽  
Iron Phase ◽  
A36 Steel ◽  
Predicted Values ◽  
Boron Diffusivity ◽  
Kinetics Of

Abstract In this study, two different mathematical models have been proposed for estimating the diffusivities of boron in the Fe2B layer on ASTM A36 steel in the range of 1173 to 1273 K with exposure times of 2 to 8 h. The boride incubation period required for the formation of such a layer was constant regardless of the boriding conditions. In both approaches, the boron diffusivity in the iron phase was considered in an unsaturated matrix. The first approach was derived from the mass balance equation at the (Fe2B/substrate) interface while the second approach employed the integral diffusion model. The calculated values of boron activation energies for ASTM A36 steel were found to be very comparable for the two approaches (161.65 and 160.96 and kJ mol-1). Afterwards, these values of activation energy were confronted with the results from the literature. Experimental validation of these two approaches has been done by comparing the experimental value of Fe2B layer thickness measured at 1123 K for 2.5 h with the simulated values. Finally, the predicted values of Fe2B layer thickness were in line with the experimental measurement.

DFT Benchmark Study of the O--O Bond Dissociation Energy in Peroxides Validated with High-Level Ab-Initio Calculations

2019 ◽  
Author(s):  
Danilo Carmona ◽  
Pablo Jaque ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Reference Value ◽  
Basis Set ◽  
Basis Sets ◽  
Mean Deviation ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
The Mean ◽  
Experimental Values ◽  
High Level ◽  
Almost All

<div><div><div><p>Peroxides play a central role in many chemical and biological pro- cesses such as the Fenton reaction. The relevance of these compounds lies in the low stability of the O–O bond which upon dissociation results in radical species able to initiate various chemical or biological processes. In this work, a set of 64 DFT functional-basis set combinations has been validated in terms of their capability to describe bond dissociation energies (BDE) for the O–O bond in a database of 14 ROOH peroxides for which experimental values ofBDE are available. Moreover, the electronic contributions to the BDE were obtained for four of the peroxides and the anion H2O2− at the CBS limit at CCSD(T) level with Dunning’s basis sets up to triple–ζ quality provid- ing a reference value for the hydrogen peroxide anion as a model. Almost all the functionals considered here yielded mean absolute deviations around 5.0 kcal mol−1. The smallest values were observed for the ωB97 family and the Minnesota M11 functional with a marked basis set dependence. Despite the mean deviation, order relations among BDE experimental values of peroxides were also considered. The ωB97 family was able to reproduce the relations correctly whereas other functionals presented a marked dependence on the chemical nature of the R group. Interestingly, M11 functional did not show a very good agreement with the established order despite its good performance in the mean error. The obtained results support the use of similar validation strategies for proper prediction of BDE or other molecular properties by DF Tmethods in subsequent related studies.</p></div></div></div>

Markov Jump Linear System Analysis of a Microgrid Operating in Islanded and Grid Tied Modes

2020 ◽  
Author(s):  
Gilles Mpembele ◽  
Jonathan Kimball
Keyword(s):  
Monte Carlo ◽  
Power Systems ◽  
Power System ◽  
System Analysis ◽  
Differential Algebraic Equations ◽  
Algebraic Equations ◽  
Markov Jump ◽  
Numerical Application ◽  
Conditional Moments ◽  
Markov Jump Linear Systems

<div>The analysis of power system dynamics is usually conducted using traditional models based on the standard nonlinear differential algebraic equations (DAEs). In general, solutions to these equations can be obtained using numerical methods such as the Monte Carlo simulations. The use of methods based on the Stochastic Hybrid System (SHS) framework for power systems subject to stochastic behavior is relatively new. These methods have been successfully applied to power systems subjected to</div><div>stochastic inputs. This study discusses a class of SHSs referred to as Markov Jump Linear Systems (MJLSs), in which the entire dynamic system is jumping between distinct operating points, with different local small-signal dynamics. The numerical application is based on the analysis of the IEEE 37-bus power system switching between grid-tied and standalone operating modes. The Ordinary Differential Equations (ODEs) representing the evolution of the conditional moments are derived and a matrix representation of the system is developed. Results are compared to the averaged Monte Carlo simulation. The MJLS approach was found to have a key advantage of being far less computational expensive.</div>

Application of Pregelatinized Meal of Rice and Sorghum in the Preparation of Instant Soups: Centesimal Characterization, Technological, Microbiological and Sensory Quality

2019 ◽  
Vol 15 ◽  
Author(s):  
Gomes Acg ◽  
Lima Mcpm ◽  
Caliari M ◽  
Alves Dg ◽  
Machado Alb ◽  
...  
Keyword(s):  
Fast Food ◽  
Water Solubility ◽  
Potato Starch ◽  
Rice Flour ◽  
Extrusion Process ◽  
Experimental Development ◽  
Sorghum Flour ◽  
Predicted Values ◽  
Experimental Values ◽  
Physical And Chemical

Due to the technological importance that the extrusion process represents in the application of fast food, the objective of this work was to apply pregelatinized rice and sorghum flours in the development of an instant preparation soup and to evaluate its centesimal, technological, and their sensorial analysis. Ten formulations of the instant soup were prepared from the mixtures experimental design. According to the experimental results, it can be stated that the predicted values corroborated with the experimental values, that is, a mixture was obtained for the instant soup with the characteristics of water absorption, water solubility, color, luminosity and viscosity close to the predicted by the models. After the physical and chemical analysis, the microbiological characterization of the best formulation defined by the desirability test was used, which demonstrated that the product is suitable to microbiological standards. The results obtained showed that the 80:10:10 instant soup formulation of pregelatinized rice flour, pregelatinized sorghum flour and potato starch allowed the experimental development of a new product with good nutritional characteristics benefits. It was obtained a food with good technological characteristics solubility and absorption in water, good viscosity, light color and with good sensory acceptance by the tasters.

Sign in / Sign up

Export Citation Format

Share Document