Diffusional Growth Kinetics of Boride Layers on Iron-Chromium Alloys

Dybkov, V. I.; Goncharuk, L. V.; Khoruzha, V. G.; Meleshevich, K. A.; Samelyuk, A. V.; Sidorko, V. R.

doi:10.4028/www.scientific.net/ssp.138.181

Cited by 27 publications

(21 citation statements)

References 10 publications

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“…e result obtained by equation 31is the same as that obtained in equation (19) estimated by a steady-state Table 2: Estimated values of boron diffusion coefficients in the Fe 2 B layer using the second approach (non-steady-state diffusion model).…”

Section: E Two Diffusion Modelssupporting

confidence: 54%

“…Type of layer (19) would appear to imply that the non-steady-state diffusion model is superior to the steady-state diffusion model and so should always be used. However, in many interesting cases, the models are equivalent as in this case.…”

Section: Temperature (K)mentioning

confidence: 99%

“…e suggested models were validated by comparing the experimental value of Fe 2 B layers' thickness with the theoretical result. By substituting equation (19) (32) Figure 10 shows the SEM micrographs of the cross sections of borided ASTM A36 steels at 1123 K for 2.5 h. Table 4, presents the values of the theoretical result of Fe 2 B layers' thickness with the experimental data. A good concordance was the observed value between the experimental result and the simulated value for the given boriding condition.…”

Section: Experimental Validation Of the Kinetic Modelsmentioning

confidence: 99%

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Modeling of the Growth Kinetics of Boride Layers in Powder-Pack Borided ASTM A36 Steel Based on Two Different Approaches

Domı́nguez

Gómez-Vargas

Parga

et al. 2019

Advances in Materials Science and Engineering

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An indispensable tool to choose the suitable process parameters for obtaining boride layer of an adequate thickness is the modeling of the boriding kinetics. In this work, two mathematical approaches were used in order to determine the value of activation energy in the Fe2B layers on ASTM A36 steel during the iron powder-pack boriding in the temperature range of 1123–1273 K for treatment times between 2 and 8 h. The first approach was based on the mass balance equation at the interface (Fe2B/substrate) and the solution of Fick’s second law under steady state (without time dependent). The second approach was based on the same mathematical principles as the first approach for one-dimensional analysis under non-steady-state condition. The measurements of the thickness (Fe2B), for different temperatures of boriding, were used for calculations. As a result, the boron activation energy for the ASTM A36 steel was estimated as 161 kJ·mol−1. This value of energy was compared between both models and with other literature data. The Fe2B layers grown on ASTM A36 steel were characterized by use of the following experimental techniques: X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray Spectroscopy (EDS). Finally, the experimental value of Fe2B layer’s thickness obtained at 1123 K with an exposure time of 2.5 h was compared with the predicted thicknesses by using these two approaches. A good concordance was achieved between the experimental data and the simulated results.

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Section: E Two Diffusion Modelssupporting

confidence: 54%

Section: Temperature (K)mentioning

confidence: 99%

Section: Experimental Validation Of the Kinetic Modelsmentioning

confidence: 99%

See 1 more Smart Citation

Modeling of the Growth Kinetics of Boride Layers in Powder-Pack Borided ASTM A36 Steel Based on Two Different Approaches

Domı́nguez

Gómez-Vargas

Parga

et al. 2019

Advances in Materials Science and Engineering

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“…Calculations showed this system to provide a good fit to experimental data obtained with iron boride and other compound layers. Full set of appropriate values of diffusional constants k can be found in [40][41][42][43][44][45][46][47][48][49].…”

Section: If the Conditionmentioning

confidence: 99%

“…Experimental data [38][39][40][41][42][43][44][45][46][47][48][49] on the interaction of five iron-chromium alloys (5-30% Cr) and two industrial steels containing 13 and 25% chromium with boron in a mixture of amorphous boron powder and KBF 4 (activator) in the temperature range of 850-950ºC at reaction times up to 43200 s are juxtaposed and discussed together with findings of other researchers in this work.…”

Section: Introductionmentioning

confidence: 99%

Basics of Formation of Iron Borid e Coatings

Dybkov

2016

J. Miner. Met. Mater. Eng.

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Main features of formation of iron boride layers in surface coatings on iron, its alloys, notably with chromium, and steels are discussed. Those include their microstructure, phase identity, chemical composition, sequence of occurrence, growth kinetics, and dry wear resistance. Two different kinds of layer microstructure (single-phase and twophase) are shown to exist. Boriding of iron-chromium alloys (5-30% Cr) and chromium steels (13 and 25% Cr) at 850-950ºC and reaction times up to 43200 s is found to result in the formation of a surface coating consisting of two boride layers. In the case of Fe-Cr alloys containing 5-15% chromium and a 13% Cr steel, the outer layer bordering the boriding agent consists of the (Fe,Cr)B compound, while the inner one adjacent to the solid substrate consists of the (Fe,Cr)2B compound. Each boride layer is a homogeneous phase. It is a microstructure of the first type. With Fe-Cr alloys containing 25 and 30% chromium and a 25% Cr steel, each of two boride layers consists of two compounds. The outer layer comprises the (Fe,Cr)B and (Cr,Fe)B compounds, while the inner one comprises the (Fe,Cr)2B and (Cr,Fe)2B compounds. It is a microstructure of the second type that was not observed earlier. With Fe-Cr alloys containing 5% and 10% Cr, boriding during 3600 s leads to the formation of a single (Fe,Cr)2B layer. The (Fe,Cr)B layer occurs after the first-formed (Fe,Cr)2B layer has attained a thickness of more than 100 µm. With other alloys and steels, a reaction time of 3600 s is sufficient for both boride layers (Fe,Cr)B and (Fe,Cr)2B to form. Their distinguishing feature is a {002} texture. Boride layers with the microstructure of the second type exhibit a much higher wear resistance than those with the microstructure of the first type. The difference exceeds an order of magnitude.

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Evaluation of Boride Layer Growth on Carbon Steel Surfaces

Matijević

2014

Met Sci Heat Treat

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The kinetics of growth of the boride layer in the boronizing of carbon steels from EKABOR 3 powder is studied. Relations between the thickness of the boride layer and the parameters of the process, i.e., the temperature and the duration of the boronizing operation, and the composition of the saturated steel are derived. The morphology and the types of the borides are determined by the methods of light microscopy and x-ray diffraction. The parameters of the Arrhenius equation for the kinetics of boronizing are computed. The contour diagram obtained for the variation of the thickness of boride layer makes it possible to determine the size of the layer from data on the parameters of the process.

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Diffusional Growth Kinetics of Boride Layers on Iron-Chromium Alloys

Cited by 27 publications

References 10 publications

Modeling of the Growth Kinetics of Boride Layers in Powder-Pack Borided ASTM A36 Steel Based on Two Different Approaches

Modeling of the Growth Kinetics of Boride Layers in Powder-Pack Borided ASTM A36 Steel Based on Two Different Approaches

Basics of Formation of Iron Borid e Coatings

Evaluation of Boride Layer Growth on Carbon Steel Surfaces

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