Boron Activation Research Articles

Evolution of activation energy for boron dissolution in the borosilicate glass during the initial leaching stage

Borosilicate glass is widely used for immobilizing high-level radioactive waste. In this study, two types of borosilicate glasses, Na-borosilicate and Zr-Na-borosilicate, were subjected to leaching within a temperature range of 50-90°C, at 10°C intervals. The rate of boron consumption was measured by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) and Fourier-Transform infrared spectroscopy (FTIR) techniques, and the boron activation energy was determined through the Arrhenius equation. The boron activation energies for Na-borosilicate and Zr-Na-borosilicate glasses are approximately 46 kJ/mol and 42 kJ/mol, respectively. The activation energy, which FTIR calculated, was consistent with that obtained by ICP-OES during the initial leaching time and decreased as the leaching time increased. The decrease in activation energy of boron is because the [BO3] structure was replaced by molecular water. The FTIR method offers an alternative approach for calculating the boron activation energy and contributes to understanding the leaching mechanism in the initial leaching stage.

An Efficient Boron Source Activation Strategy for the Low-Temperature Synthesis of Boron Nitride Nanotubes

HighlightsDeveloped more efficient boron activation strategies, while establishing various low-melting growth systems.The preparation temperature of boron nitride nanotubes has been reduced to 850 °C.

Boronizing of Monel K500 alloy: Microstructural characterization and modeling of boron diffusion

In this study, the thermochemical treatments were carried out using the powder-pack boronizing method at temperatures ranging from 1123 K to 1223 K for durations of 2 to 6 h, with the aim of improving the surface properties of Monel K500 alloy. Microstructural investigation of the boride layers, conducted using optical microscopy (OM) and scanning electron microscopy (SEM), revealed a needle-like layer structure with high porosity homogeneously distributed on the surface. The results of XRD analysis showed that the boride layer contained different nickel borides (Ni2B, Ni3B, Ni4B3 and NiB12), iron borides (Fe2B and Fe3B) and complex borides (Fe4.5Ni18.5B6 and Fe3Ni3B). The presence and amount of elements in the boride layer were determined by EDS analysis. This study focused mainly on diffusion kinetics studies of boronized Monel K500 alloy. Growth kinetics of the boride layer were investigated using three different approaches such as parabolic growth model, regression model and mean diffusion coefficient (MDC) model. Boron activation energy values were calculated and found to be quite similar, at 266.14 kJ mol−1 and 266.17 kJ mol−1 using the MDC model and parabolic growth model, respectively. These values were compared with similar results reported in the literature.

Superior electro-catalytic performance achieved by the negatively charged boron atom on BC3/TM/graphene sandwich heterostructures

The sandwich heterostructures (SHSs) are novel two-dimensional materials that hold great potential as efficient electro-catalysts. In this work, we computationally designed the BC3/TM/Gr SHSs by intercalating transition metal atoms into the BC3/graphene heterostructure. After the computational screening, only BC3/Sc/Gr, BC3/Ti/Gr, BC3/Y/Gr and BC3/Zr/Gr are validated as stable SHSs. The electron donation from the intercalated TM atom results in the formation of the negatively charged boron atom (Bδ−) and activation of the BC3 surface, making the BC3/TM/Gr SHSs highly promising as single-atom catalysts (SACs). The BC3/Sc/Gr and BC3/Y/Gr SHSs exhibit potential in carbon dioxide reduction reaction (CO2RR) and carbon monoxide reduction reaction (CORR) electro-catalysis. Particularly, when BC3/Y/Gr SHS serves as CORR electro-catalyst, the step (*CHO→*CHOH) is a potential determining step, with an extremely low limiting potential (UL = −0.10 V). The BC3/Ti/Gr and BC3/Zr/Gr SHSs are suitable as hydrogen evolution reaction (HER) electro-catalysts. Specially, the BC3/Ti/Gr SHS serves as an ideal HER electro-catalyst in acid condition, with close-to-zero adsorption free energy (ΔGH = 0.006 eV) and fairly low overall activation barrier (0.20 eV). By analyzing the electronic properties, the unique adsorption activity of the Bδ− on H atom and unsaturated CO2RR intermediates is elucidated as the origin of excellent catalytic activity of BC3/TM/Gr SHSs, which is modulated by the intercalated TM atom. Our work is instructive to rational design of SACs towards energy conversion based on non-metal elements.

Fe2B layer growth kinetics on ASTM A307 steel evaluated by two diffusion models

Abstract In this study, we implemented two simple models to simulate the growth of the Fe2B layer on ASTM A307 steel through boriding. The first model considered steady-state boron diffusion, while the second model incorporated transient regime effects. In the steady-state model, the boron concentration profile within the Fe2B layer exhibited linearity. By correlating the boron chemical potential with the inward mass flux at the (Fe2B/substrate) interface, we confirmed the parabolic nature of layer growth. Both models were employed to determine the boron activation energies, yielding the same value of approximately 164 kJ mol−1. Experimental validation of the two models was conducted under two additional boriding conditions (1323 K for 1.5 and 2 h). Finally, the simulated layer thicknesses matched with the experimental values.

Study on Tritium Production and Effluent Source Term for HPR1000

During the operation of nuclear power plants, fuel fission and activation of boron and lithium in reactor coolant will produce a certain amount of tritium, which is difficult to be removed by conventional waste treatment system, and will cause certain harm to human body in the form of internal irradiation after entering the environment. In this paper, by analyzing the main sources of tritium production, the calculation model and key parameters of tritium production are evaluated, the tritium production and gas-liquid effluent source terms are obtained for HPR1000. The result shows that the activation of boron-10 in the reactor coolant is the main source of tritium production, accounting for about 66%, followed by the contribution of secondary source rods, accounting for about 30%. The gas and liquid effluents of tritium meets the requirements of GB6249-2011. The results can be used as a reference for environment impact assessment and determination of application value of tritium effluent.

In vitro bioactivity and biocompatibility assessment of PCL/PLA–scaffolded mesoporous silicate bioactive glass: Role of boron activation

Bioactive glasses with rapid biodegradation and efficient biomineralization for damaged bone tissue repair remain deficient. Based on this fact, some new types of boron-activated mesoporous Bioactive silicate glasses (BMSGs) were made to determine the feasibility of achieving their improved mechanical strength, structure, porosity, biodegradability and bone healing performance. Four samples of the form xB2O3 – (80–x) SiO2 – 15CaO – 5P2O5 with x is 0, 5, 10, and 15 mol% were prepared using a unified sol-gel/evaporation induced self-assembly (SG-EISA) process. Furthermore, the solvent casting/partial leaching method was used to Scaffold the proposed BMSGs by polycaprolactone/polylacticacid (named as BMSG-PPS). The role of boron concentration fine-tuning in modifying the glasses morphology, structure, Bioactivity and Biocompatibility was assessed in vitro by immersing them in simulated body fluid (SBF) at various durations. Intense XRD peak at 31.7° confirmed the existence of crystalline hydroxyl carbonate apatite (HCA) in the glasses. Glass made with 10 mol% of boron (BMSG-PPS10) showed the strongest crystalline peak of HCA amongst all the studied samples. FESEM image of the Scaffold surface also revealed the presence of HCA agglomeration after 168 h of immersion in the SBF. The boron-free sample (BMSG-PPS0) showed strong agglomeration of HCA and Ca to P ratio (1.78±0.01) close to bone. After 168 h of immersion in the SBF solution, the symmetric stretching of PO43–and CO32–bands in the glass became more prominent. After 168 h of immersion in the SBF, the samples’ weight loss and solution pH correspondingly varied in the range of 5.66–7.37 % and 6.80–7.02. In addition, ICP–OES analyses of the glasses verified an increase of Si release in the SBF from the silicate network, indicating their rapid biodegradation. Briefly, the proposed BMSG–PPS with improved Bioactivity and Biocompatibility may be beneficial for various bio-medical implant coating applications.

Boron activation in silicon thin films grown by PECVD under epitaxial and microcrystalline conditions

Boron doping level and boron activation in silicon thin films grown by PECVD under epitaxial (p+ epi‑Si) and microcrystalline (p+ µc-Si) conditions have been investigated as functions of the substrate material and annealing in the range of 200°C – 300°C. Hall effect measurements show that in the as-deposited state, the conductivity is mainly governed by the carrier concentration, while the hole mobility is controlled by the crystalline quality. SIMS measurements reveal that dark conductivity is not directly proportional to the boron doping level, nor to the presence of B-H complexes, suggesting that carbon contamination and the formation of B-O complexes could play an important role in the electrical properties of the material. Annealing in air resulted in an increase in the dark conductivity for all samples. However, the increase was much higher (up to two orders of magnitude) for the samples deposited on silicon-on-insulator (SOI) substrates which have better crystalline quality and displayed the highest increase in hole carrier concentration, related to boron activation. Thus, the substrate material influences both the crystalline quality and the boron incorporation in the p-type material. At high boron incorporation, the mobility limitations are likely to be due to carrier concentration rather than to the crystalline quality, indicating that p+ µc-Si conditions allow a conductivity advantage over p+ epi‑Si conditions due to a higher doping level, which makes them suitable as hole-selective contacts in solar cells.

Phase transformations and microstructure evolution of boron-containing iron concentrate during roasting under CO-CO2-N2 atmosphere: Synergistic effect of soda-ash and CO concentration

The efficient utilization of the boron-containing iron ore, China's primary source of boron, has strategic significance for the country. An innovative process that allows for the highly efficient extraction of boron and simultaneous enrichment of magnetite at a relatively low soda-ash roasting temperature (1123 K) under a CO-CO2-N2 atmosphere was proposed. The complex microstructure, composed of spinel (MgxFe3-xO4) and magnesiowustite (MgyFe1-yO), formed concurrently with the activation of boron (NaBO2) when roasting in the presence of 20 wt% Na2CO3. The spinel would be further reduced into magnesiowustite, and the magnetism of roasted samples dropped significantly with increasing CO concentration from 5.0 vol% to 7.5 vol% with a constant CO/(CO + CO2) ratio of 10 %. DFT calculation results demonstrated that Mg-doped Fe3O4 (MgxFe3-xO4) enhances the adsorption of CO molecules and intensifies the reduction of Fe3O4.

A Chemoselective Polarity‐Mismatched Photocatalytic C(sp3)−C(sp2) Cross‐Coupling Enabled by Synergistic Boron Activation**

AbstractWe report the development of a C(sp3)−C(sp2) coupling reaction using styrene boronic acids and redox‐active esters under photoredox catalysis. The reaction proceeds through an unusual polarity‐mismatched radical addition mechanism that is orthogonal to established processes. Synergistic activation of the radical precursor and organoboron are critical mechanistic events. Activation of an N‐hydroxyphthalimide (NHPI) ester by coordination to boron enables electron transfer, with decomposition leading to a nucleofuge rebound, activating the organoboron to radical addition. The unique mechanism enables chemoselective coupling of styrene boronic acids in the presence of other alkene radical acceptors. The scope and limitations of the reaction, and a detailed mechanistic investigation are presented.

A Chemoselective Polarity-Mismatched Photocatalytic C(sp3 )-C(sp2 ) Cross-Coupling Enabled by Synergistic Boron Activation.

We report the development of a C(sp3 )-C(sp2 ) coupling reaction using styrene boronic acids and redox-active esters under photoredox catalysis. The reaction proceeds through an unusual polarity-mismatched radical addition mechanism that is orthogonal to established processes. Synergistic activation of the radical precursor and organoboron are critical mechanistic events. Activation of an N-hydroxyphthalimide (NHPI) ester by coordination to boron enables electron transfer, with decomposition leading to a nucleofuge rebound, activating the organoboron to radical addition. The unique mechanism enables chemoselective coupling of styrene boronic acids in the presence of other alkene radical acceptors. The scope and limitations of the reaction, and a detailed mechanistic investigation are presented.

Modelling boron diffusion for Fe2B layer formation: comparative kinetics analysis in pack-boronized AISI 4147 steel

Abstract In this current research paper, the modelling of boron diffusion during the powder-pack boronizing was achieved by utilizing two kinetics approaches: the integral method and average diffusion coefficient (ADC) method. This integral method used a general solution of algebraic differential equations (DAEs) system. The powders mixture composed of: 33.5 wt% B4C, 5.4 wt% KBF4 and 61.1 wt% SiC was employed to generate the Fe2B layers on AISI 4147 steel in the interval of 1123–1273 K for 2–8 h. The obtained surface layers have been characterized by Scanning electron microscopy (SEM) to examine the growth front with a typical saw-toothed morphology. The crystalline nature of boride phase has been verified by X-ray diffraction technique (XRD). The calculation results arising from the two models led to the similar boron activation energy in Fe2B equal to 196.19 kJ mol−1. Additionally, both models were checked out empirically by selecting three extra boronizing conditions obtained at 1273 K for increasing times (2.5, 4.5 and 8.5 h). The predicted layers’ thicknesses were found to be in line with the experimental results.

Kinetic Modelling of Powder-Pack Boronized 4Cr5MoSiV1 Steel by Two Distinct Approaches

This work attempts to model the powder-pack boronizing kinetics of 4Cr5MoSiV1 steel in the interval of 1133 and 1253 K in order to predict the layers’ thicknesses. The first approach is referred to as the bilayer model and relies on the conservation principle of mass balance equations at the two phase fronts accounting for the linearity of boron distribution across each boride phase. The second approach deals with the application of dimensional analysis to simulate the boronizing kinetics of 4Cr5MoSiV1 steel. Using the bilayer model and the classical parabolic law, the boron activation energies in FeB and Fe2B were evaluated and discussed in light of the literature data. The estimated boron activation energies from the bilayer model were respectively equal to 164.92 and 153.39 kJ mol−1. These values were very comparable to those calculated from the classical parabolic law. Finally, it was proven that the dimensional analysis was able to simulate the layers’ thicknesses for the selected processing parameters.

Characterizations and Kinetic Modelling of Boride Layers on Bohler K190 Steel

In this study, the Bohler K190 steel, manufactured by the powder metallurgy (PM) process, was subjected to the boronizing process. This thermochemical treatment was carried out in the range of 1173 to 1323 K, for 1–10 h. The scanning electron microscopy (SEM) was utilized for examining the morphology of layers’ interfaces with a dual-phase nature and measuring the layers’ thicknesses. The obtained boronized layers had a maximum thickness of 113 ± 4.5 µm. The X-ray diffraction analysis (XRD) confirmed the presence of FeB and Fe2B layers. The energy dispersive spectroscopy (EDS) mapping and EDS point analysis were used to investigate the redistribution of chemical elements within the boronized layers and the transition zone. The values of Vickers microhardness of Fe2B, FeB, and transition zone were estimated. Finally, the boron activation energies in FeB and Fe2B were found to be 204.54 and 196.67 kJ·mol−1 based on the integral method and compared to the literature results.

Characterization of dual phase boride coatings on Sverker 3 steel and simulation of boron diffusion

AbstractThe Sverker 3 steel was treated by solid boriding in the range 1173–1273 K for holding times ranged from 1 to 7 h. The processes resulted in two-phase (FeB + Fe2B) boride layers except the treatment at 1173 K for 1 h where the Fe2B was formed only. The growth of borides obeys a typical parabolic law, with the maximum thickness of 120 ± 4.5 µm. Considerable redistribution of carbon and alloying elements took place during boronizing; carbon and silicon were pushed out from borides while chromium and tungsten were rather gathered in these compounds. The microhardness of Fe2B ranged between 1600 and 1700 HV 0.1, and that of FeB reached 2100–2200 HV 0.1. The average diffusion coefficient (ADC) approach was applied by assuming the linearity of boron concentration profiles across the iron boride layers. This approach allowed us to obtain the boron diffusivities in both the FeB and Fe2B. Afterwards, the boron activation energies in both layers were obtained by fitting the temperature evolution of calculated boron diffusivities in the two iron boride phases with the Arrhenius relations. The assessed boron activation energies in FeB and Fe2B were, respectively, 215.18 and 203.6 kJ mol−1. Finally, a comparison of these values of energies was made with literature results.

Characterization and Boron Diffusion Kinetics on the Surface-Hardened Layers of Royalloy Steel

The Royalloy steel was boronized at 1173, 1223, 1248, 1273 or 1323 K for 1, 3, 5, 7 or 10 h using a Durborid powder mixture. The boronized samples were analyzed by scanning electron microscopy, X-ray diffraction and Vickers microhardness testing. The kinetic activity of boronized layers growth obeys the parabolic law, and the maximum thickness was 182 ± 10 µm. The thickness of FeB makes up to 40% of the total layer thickness. The obtained layers have two phases, which were composed of FeB and Fe2B phases, except for the sample boronized at 1173 K for 1 h which had an Fe2B layer only. The microhardness of the Fe2B phase had a range of 1370–1703 HV0.1, and that of the FeB phase was within 1727–2231 HV0.1. During the boronizing process, the chromium created extra particles with the highest amount of chromium in the transient region. The highest amount of silicon was observed at the boride layer/substrate interface. The amount of manganese was slightly lower in the boride layers compared to the amount in the substrate. Finally, the integral diffusion model was applied to determine the boron activation energies in the FeB and Fe2B layers, and this was followed by a comparison with the literature data.

Fast protodeboronation of arylboronic acids and esters with AlCl3 at room temperature

AlCl3-mediated protodeboronation of arylboronic acids and esters is reported herein. This method features mild reaction conditions, high reaction yields, as well as short reaction times. Mechanistic studies based on 11B NMR spectroscopy suggest that it might proceed through initial boron activation by coordination of AlCl3 to the oxygen atom of arylboronic acid or ester groups.

Powder-pack boronizing of CoCrFeNiAl0.5Nb0.5 HEA: Modeling of kinetics, microstructural, mechanical, and tribological characterizations

This study is dedicated to the detailed investigation of boronization kinetic, microstructural, mechanical, and wear properties of high entropy alloys (HEAs) considering their sluggish diffusion effect properties. A CoCrFeNiAl0.5Nb0.5 HEA was powder-pack boronized in the interval of 850–1050 °C for 2, 4, and 6 h in the boronizing medium containing 90 wt% of boron carbide and 10 wt% of sodium tetrafluoroborate. Boronizing of CoCrFeNiAl0.5Nb0.5 HEA was successfully produced. The obtained multi-phase boronized layers were characterized by compactness and flatness showing up inside its typical dendritic zones. The X-Ray Diffraction (XRD) studies showed the presence of ternary phases inside the boronized layers having a thickness of 4.38–92.16 µm. The nano and microhardness values were also determined and the adhesion force was analyzed through the Rockwell indentation tests. In addition, the Vickers fracture toughness values (0.46–1.83 MPa m−1/2) of the treated samples were found to be very dependent on the boronizing temperature. The wear losses have decreased due to the increase in hardness and an improvement of up to 99% has been achieved. The average diffusion coefficient model was implemented to deduce the boron activation energy in the CoCrFeNiAl0.5Nb0.5 HEAs. Finally, the predicted layers’ thicknesses were coincident with the experimental data.

A novel process for highly efficient separation of boron and iron from ludwigite ore based on low-temperature microwave roasting

A facile route for simultaneous activation and separation of boron and iron from ludwigite ore at low temperature under the synergistic effect of microwave heating and sodium carbonate (Na2CO3) was reported. It was shown that the composite system would absorb microwave energy well and promote the reduction of iron oxides and formation of water-soluble metaborate derived from szaibelyite, with restrained decomposition of lizardite which demanded less Na2CO3. After roasting at only 700 °C, the metallized briquettes with iron metallization degree (ηFe) of 90.5% were produced. By milling and leaching and subsequent magnetic separation of the metallized pellets, the boron-rich leachate with boron leaching percentage of 85.1% and direct reduced iron (DRI) powders with total iron content (TFe) of 90.6 wt%, ηFe of 97.6%, and iron recovery (εFe) of 91.2% could be obtained. Boron and iron had much better separation performance than that achieved by the conventional route.

Bilayer growth kinetics and tribological characterization of boronized AISI M2 steel

Abstract The AISI M2 steel has been treated by solid boriding between 1123 and 1273 K for an exposure time of 2–8 h. In these circumstances, a bilayer constituted by FeB and Fe2B has been formed with interfaces nearly flat. The tribological behavior and decohesion resistance of boride coatings were studied by using the following characterizations: (Rockwell-C cohesion, pin-on-disc and wear scratch tests). The modeling of process kinetics was undertaken based on two different approaches (the mass balance equations and the integral method). The assessed values of boron activation energies in FeB and Fe2B arising from the two models were nearly similar. In addition, the predicted layers’ thicknesses at 1243 and 1273 K during 10 h were concordant with the experimental values.