Fe2B Layers Research Articles

Boriding Kinetics of FeB and Fe2B Layers on AISI M2 Steel by the Integral Diffusion Model

Boriding Kinetics of FeB and Fe2B Layers on AISI M2 Steel by the Integral Diffusion Model

Investigation of tribological behaviour and diffusion model of Fe2B layer formed by pack-boriding on SAE 1020 steel

In this study, a substitute boriding powder including boric acid as boron source was prepared and employed for boronizing of SAE 1020 steel. The boronizing processes were performed at 850, 900 and 950 °C for 4, 8 and 12 h. The formed boride layers were identified by varied experimental methods such as optical microscope, SEM and WDS analysis. As an outcome of the analyses, the boride layer containing only Fe2B phase with saw-tooth morphology was specified on surface of the samples. A diffusion model was proposed to estimate the coefficients of boron diffusion in the Fe2B layers. The value of boron activation energy for SAE 1020 steel was calculated as 183.14 kJ/mol and the result was contrasted with literature data. As a result of the microhardness measurements, the average hardness value of Fe2B layer was about between 1200 and 2000 HV0.1. The average hardness values of the transition zone and matrix zone were determined to be approximately 160 HV0.1 and 151 HV0.1, respectively. This study mainly concentrates on the tribological properties of borided SAE 1020 steel with using alternative boriding powder. Coefficient of friction graph was drawn for each sample and the wear rates were calculated. It was specified that specific wear rate of borided samples was roughly 47 times lower than that of unborided samples.

Investigation of using pumpkin seed oil methyl ester as a fuel in a boron coated diesel engine

In this study, pumpkin seed oil was converted into biodiesel using alkali-catalyzed transesterification. Physicochemical properties were examined based on ASTM standards and compared with commercial diesel fuel (D-2). To improve the performance of engine, combustion chamber components like piston head, cylinder liner, intake and exhaust valves were thermally coated. Boronizing method was applied for the first time in the coating of conventional cast iron cylinder liner surface to reduce heat transfer. 150 μm thick Fe2B layer was deposited on the surfaces. So, the conventional engine was converted into low heat rejection engine. In order to determine the insulation affect of Fe2B layer, 3-D finite element transient-state analyses were done to the both coated and standard cylinders. D-2 and PSME fuel blends were used as test fuels. Emission and performance of the coated engine (CE) have been investigated for both fuels. CE showed lower emission and higher performance. For D-2 and B-20 fuels; results showed that, CO decreased by 13–15%, HC decreased by 53–36%, smoke density decreased by 15–36%, respectively. But NOx emission increased by 11–37% for D-2/B-20 fuels, respectively. Besides, BTE for D-2/B-20 fuel increased by 10-10% while BSEC decreased by 3–9%, respectively.

SIMULATION MODEL OF THE GROWTH KINETICS OF Fe2B LAYERS WITH CONSIDERATION OF THE BORIDE INCUBATION TIME EFFECT

In this work, a mathematical model for simulating the thermochemical boronizing process is presented. The diffusion model used in this paper is based on Fick’s laws by solving the mass balance equation of the (FeB/Fe2B) interface. In this developed model, the effect of boride incubation times during the formation of Fe2B layers on Armco iron was considered. To demonstrate the validity of our calculations, the simulation results are compared with experimentally obtained data on borided Armco iron, which allowed us to verify the validity of the model. Therefore, a good concordance was observed when comparing the experimental parabolic growth constants taken from the literature with our simulated values of the parabolic growth constants from the present diffusion model. From this study, it has been found that the incubation time has a very important influence on the evolution of the kinetics of the boride layers.

Cálculo de la energía de activación de la difusión de boro en la capa de Fe2B en la borurización por empaquetamiento de los aceros SAE 1050 y DIN UC1

The layer of iron boride (Fe2B) was formed on the surface of two steels, SAE 1005 and DIN UC1; after being subjected a treatment by packaging, and it was used to study the effect of the chemical composition on the thickness of the layer, the growth kinetics and the activation energy for boron diffusion. The mass balance equation and the parabolic growth law were used at the Fe2B/substrate interface, considering that the layer begins to grow after an incubation time (t0). The microscopic analysis revealed in the iron boride its form irregular, type saw teeth, in both steels. The present phases were identified by X-Ray diffraction, corroborating the presence of a single-phase Fe2B layer. An Arrhenius-type equation was used to correlate the layer thickness with the activation energy, which for this study was determined in 132.3 and 143.9 kJ mol-1 for SAE1005 and DIN UC1 steels, respectively.

Characterization and boriding kinetics of AISI T1 steel

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.

Sliding Wear Behavior of Friction Couples Primarily Selected for Corrosion Resistance: Iron Boride/Iron Boride and Iron Boride/Yttria-Stabilized Zirconia

Wear mitigation in a sliding couple is challenging if wear has to be minimized on both surfaces. In this paper, ball-on-disk testing is performed on sliding couples where both surfaces (ball and disk) are treated for wear resistance. Studied materials are pack borided H13 tool steel (ASTM A681), pack borided AISI 420 stainless steel (ASTM A276) and plasma sprayed yttria-stabilized zirconia (YSZ). Borided H13 steel exhibits a single phase Fe2B layer, while AISI 420 has a double phase layer, with FeB on the outer surface. Both FeB/Fe2B and FeB/YSZ couples generate three-body abrasion. In the latter case, mass transfer occurs from the ball to the disk as well. Friction coefficient is ~0.6 for the AISI 420/Fe2B and FeB/Fe2B sliding pairs, with less vibration on the latter and wear rates close to 10−3 mm³·(N·m)−1 for both the ball and the disk. In comparison, the FeB/YSZ pair has a friction coefficient of ~0.65, a similar total mass loss, but a much higher wear rate for YSZ than for FeB.

Comparative performance and emission characteristics of peanut seed oil methyl ester (PSME) on a thermal isolated diesel engine

In this research, cylinder liners of a diesel engine were coated with a 150 μm thick Fe2B layer using boronizing method. The upper surface of the piston was coated with a 300 μm thick CoNiCrAlYttra + NiCrBSi layer by using plasma spraying method. D-2, biodiesel (PSME-100) and blend (PSME-50) were used as test fuels. PSME fuel was produced through alkali catalyzed transesterification method. As-prepared fuels were used separately in coated (CE) and standard engines (SE) to compare performance and exhaust emission of both engines. In order to see the isolation effect of Fe2B layer, 3-D finite element transient-state analyses were carried out. According to the results, brake thermal efficiency (BTE) and exhaust gas temperature (EGT) of coated engine were considerably enhanced while brake specific fuel consumption (BSFC), CO, HC and smoke emission were decreased compared to those of standard engine. However, NOx emission of CE was higher than that of uncoated one, which was attributed to high combustion temperature and long combustion process in CE. These results were further confirmed with finite element simulation. The decreasing BSFC and increasing BTE for coated engine has been attributed to the elevated temperature of the combustion chamber by the effect of thermal insulation.

LS-SVM approach for modeling the growthe kinetics of FeB and Fe2B layers formed on Armco iron

LS-SVM approach for modeling the growthe kinetics of FeB and Fe2B layers formed on Armco iron

Investigation of high temperature dry sliding behavior of borided H13 hot work tool steel with nanoboron powder

Boride layer characterization and dry sliding wear behaviors of borided H13 steel at different durations and temperatures with nanoboron powder have been investigated. A single phase boride layer was formed at 800 °C and a double phase boride layer was obtained at 900 °C and 1000 °C. According to the boriding process with Ekabor II, higher ratio FeB/FeB + Fe2B and total boride layer were formed when nanoboron was used in the boriding process. It has been observed that the increment in the boriding temperature and boriding duration has increased the boride layer thickness from 6,34 μm to 103.26 μm. Manganese boride and chromium boride phases were determined along with iron borides in the boride layer. The hardnesses of borides formed on the H13 steel reached 2028 HV0.1 and the change in hardness from the surface to the interior was slower at samples which were borided at higher temperatures and durations. Fracture toughness was found to be in the range of 1.32–5.23 MPa-m1/2 depending on boronizing time in samples which were borided at 1000 °C. The increase in the boriding temperature and boriding duration led to increased wear resistance. At high temperature, microcrack-induced plastic deformation and fatigue; at room temperature, microcrack formation were dominant wear mechanisms.

Modeling of the Growth Kinetics of Boride Layers during the Diffusion Annealing Process

In the current work, a diffusion model was suggested to estimate the boron activation energies for FeB and Fe2B layers on the gas-borided Armco iron at temperatures of 1073, 1173, and 1273 K for a treatment time varying between 1.33 and 4 h. This model takes into account the effect of boride incubation times during the formation of the FeB and Fe2B phases. The mass balance equations were reformulated to describe the evolution of boride layers after applying the diffusion annealing process. In addition, the time needed to completely dissolve the FeB phase in the boride layer was also predicted. This predicted time was influenced by the boriding parameters during the diffusion annealing process.

Investigation of Growth Kinetics of Fe2B Layers on AISI 1518 Steel by the Integral Method

Abstract The AISI 1518 steel was pack-borided in the temperature range 1123–1273 K for a treatment ranging from 2 to 8 h. A compact single boride layer (Fe2B) was formed at the surface of the AISI 1518 steel using the mixture of powders composed of 20 % B4C, 10 % KBF4 and 70 % SiC. The following experimental techniques such as scanning electron microscopy coupled with EDS analysis and X-ray diffraction analysis were employed to characterize the pack-borided AISI 1518 steel. An alternative model, based on the integral mass balance equation, was used to estimate the boron diffusion coefficients in the Fe2B layers in the temperature range 1123–1273 K. Finally, the value of activation energy for boron diffusion in the AISI 1518 steel was estimated and compared with the literature data. Furthermore, the present model was validated by comparing the experimental value of Fe2B layer thickness, obtained at 1253 K for 2 h of treatment, with the predicted value.

Tribocorrosion behavior of boronized AISI 4140 steel

In this study, AISI 4140 steel was boronized using powder-pack‑boronizing process, seeking to produce a monophasic iron boride (Fe2B) layer. The microstructural and chemical characteristics were evaluated by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), respectively and Grazing incidence X-ray diffraction (GIXRD). Mechanical behavior was probed by instrumented indentation while tribological behavior was determined through pin-on-disc tests. For the pin-on-disc tests, two condition were evaluated, dry condition and also immersed in 3.5% NaCl solution, which was connected to a potentiostat, monitoring the open circuit potential (OCP). The single Fe2B layer was indeed obtained with a thickness around 42μm. The iron boride layer showed significantly lower wear rate and also lower coefficient of friction (COF) during tribocorrosion tests, in comparison with unboronized specimens. An opposite behavior was verified during dry tribological tests, where unboronized samples presented lower COF behavior.

Microabrasive wear behavior of borided steel abraded by SiO2 particles

Boriding treatment was applied to AISI 1020 steel to improve its wear resistance. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy, Vickers microhardness testing, fracture toughness, and confocal microscopy. The microscale abrasive wear behavior was also investigated. SiO2 abrasive particles were used as abradant with slurry concentrations of 0.5 and 1.0g/cm3. Normal loads of 0.49 and 0.98N were used. Fe2B phase was identified in the boride layer via XRD analysis. The Fe2B layer was 169μm thick with a mean hardness of 1608±101 HV0.05 and fracture toughness of 5.35±1.43MPam1/2. A reduction in the hardness of the outermost surface of the boride layer was observed owing to the formation of a porous region. Boriding treatment improved the wear resistance of the steel substrate. Sliding abrasive wear was the main mechanism under all tested conditions. The presence of micro-rolling abrasion and fracture-based mechanisms was observed for untreated and borided samples, respectively.

Effects of Heat Treatment on Phase Transformation and Corrosion Resistance of Boride Layer on Austenitic Stainless Steel AISI 304

The austenitic stainless steel AISI 304 was thermochemically surface treated using a powder-packed boronizing process at a temperature of 950 °C for about 4 hours. Double-phase boride layer (FeB and Fe2B) was detected and then investigated for the corrosion resistance compared with the untreated one. Heat treatment was performed at a temperature range of 800 to 900 °C for 2 hours on the boronized austenitic stainless steel AISI 304 to diminish the double-phase boride layer. Afterward, corrosion tests were performed to clarify the effects of heat treatment as well as phase transformation on the corrosion resistance of the boronized austenitic stainless steel AISI 304. The results of this study showed that the formation of single-phase Fe2B layer offers the best corrosion resistance.

Kinetics of Formation of Fe2B Layers on AISI S1 Steel

In the present work, the AISI S1 steel was pack-borided in the temperature range 1123-1273 K for 2- 8 h to form a compact layer of Fe2B at the material surface. A recent kinetic approach, based on the integral method, was proposed to estimate the boron diffusion coefficients in the Fe2B layers formed on AISI S1 steel in the temperature range 1123-1273 K. In this model, the boron profile concentration in the Fe2B layer is described by a polynomial form based on the Goodman’s method. As a main result, the value of activation energy for boron diffusion in AISI S1 steel was estimated as 199.15 kJmol-1 by the integral method and compared with the values available in the literature. Three extra boriding conditions were used to extend the validity of the kinetic model based on the integral method as well as other diffusion models. An experimental validation was made by comparing the values of Fe2B layers’ thicknesses with those predicted by different diffusion models. Finally, an iso-thickness diagram was proposed for describing the evolution of Fe2B layer thickness as a function of boriding parameters.

Optically-induced changes in magnetic properties of Fe2B/BiFeO3 heterostructure

Optical control of magnetic properties in exchange coupled photostrictive/ferromagnetic heterostructures is of great fundamental and technical interest for application in information storage, spintronic and microwave magnetic devices. In the present research, an optical modification of exchange bias field and magnetic properties of Fe2B/BiFeO3 heterostructure has been reported. A Fe2B/BiFeO3 bilayer and a BiFeO3 single-layer were deposited on (001)-SrTiO3 substrate by pulsed laser deposition technique. Magneto-optical hysteresis loops and x-ray diffraction pattern of the samples were recorded under light illumination with a wavelength of 405 nm at different intensities. Recorded hysteresis loops showed exchange bias coupling between ferromagnetic Fe2B and antiferromagnetic BiFeO3 layers. In addition, the results showed optically-induced changes in exchange bias and coercive fields. A critical point, in the variation of the exchange bias field with light intensity, was observed at 330 ± 10 mW/cm2. The behaviour of the exchange bias field was changed at this critical point with enhancement of the light intensity. Furthermore, the X-ray diffraction results indicated that light illumination led to an out of plane tensile strain in the BiFeO3 layer and this strain led to manipulation of the BiFeO3 magnetization. Therefore, the observed optically-induced changes can be related to the photo-induced strain in the BiFeO3 layer.

Sliding wear of borided sintered AISI M2 steel coated with AlTiN/CrN multilayer

In this work, the effect of the combination of solid boriding treatment on High Speed Steel AISI M2 produced by conventional powder metallurgy (P/M) and AlTiN/CrN film deposition by cathodic arc PVD process is evaluated in terms of the ability to withstand load during sliding wear tests and in terms of adhesion of the multilayer film. The wear resistance of the compound was evaluated by pin-on-disc sliding tests using variable speeds (0.1 m/s and 0.3 m/s) and alumina counter-body diameters (3 mm and 6 mm). The boriding treatment in AISI M2 steel promoted the formation of FeB and Fe2B layers. The average hardness of the borided layer (2162 HV0.025) was approximately 2 times greater than the hardness of quenched and tempered AISI M2 steel (945 HV0.025). The average hardness of the multilayer film was 3912 ± 504.76 HV0.025. The Borided + Film (BF) samples presented higher dry sliding wear resistance in all test conditions. For BF samples, wear on the counter-body was greater and the material removed from the counter-body formed a transfer layer onto the track, resulting in negative wear volume for some test conditions. The boriding treatment improved resistance to plastic deformation in both Borided (B) and Borided + Film (BF) conditions.

A Diffusion Model for the Fe2B Layers Formed on a Ductile Cast Iron

A Diffusion Model for the Fe₂B Layers Formed on a Ductile Cast Iron

Magnetic anisotropies and its optical manipulation in epitaxial bismuth ferrite/ferromagnet heterostructure

Exchange-coupled BiFeO3/ferromagnet thin film heterostructures are promising for a fast and power efficient control of magnetization of the ferromagnetic layer. In the paper, the results of the study of magnetic properties of the epitaxial Fe2B/BiFeO3 heterostructure on (001)-SrTiO3 substrate with ferromagnetic resonance (FMR) spectroscopy are presented. The hierarchy of magnetic anisotropies that determine the angular variation of the resonance field in-plane and in-/out-of the plane of the system include the tetragonal four-fold and uniaxial terms for the Fe2B layer, uniaxial term for antiferromagnetic BiFeO3 layer and the exchange coupling at the interface. We find out that the exchange bias direction can be switched by a strong enough applied magnetic field. Both the exchange bias and an in-plane FMR resonance field of the heterostructure are strongly affected by the illumination with λ = 405 nm light. An optical tunability of the exchange bias and ferromagnetic resonance fields of the heterostructure has been demonstrated.