Boron Powder Research Articles

Precise fabrication and superior combustion properties of n-B pomegranate microspheres based on a new dissolution-dispersion-coating method

To enhance the reactivity and combustion efficacy of boron powders, a new dissolution-dispersion-coating (DDC) method of fabricating nano-boron (n-B) pomegranate microspheres were developed. Metal nanoparticles were uniformly encapsulated within n-B microspheres, which varied in size from 2 to 500 μm. The spheroidization mechanism of microsphere structure was investigated. Subsequently, the ignition and combustion performance of the prepared pomegranate microspheres were evaluated by combustion tests at 0.2 and 0.5 MPa, respectively. The results demonstrated that the n-B microspheres of F5 (75 wt% n-B@17 wt% NC@8 wt% n-Ti) exhibited superior performances, achieving the largest flame area, minimal ignition delay time and combustion time. The combustion thermal value and combustion residue analysis indicated that the content of available boron in the F5 microspheres exceeded 72.6 % and the combustion was complete. This study provides a novel approach to enhance the ignition and combustion efficiency of n-B powders.

Doping of Mn2+ ion into boron quantum dots with enhanced fluorescence properties for sensing of L-thyroxine biomarker and bioimaging applications

L-thyroxine serves as a primary biomarker for diagnosing hypothyroidism and it is also utilized in hormone replacement therapy. Regular assessment of thyroxine levels is crucial for preventing health issues in hypothyroid patients, suggesting the requirement of a facile analytical tool for the detection of L-thyroxine. In this work, a straightforward and efficient synthetic method is introduced for in-situ preparation of Mn2+-doped boron quantum dots (Mn2+@B-QDs) derived from boron powder through a solvothermal reaction. The introduction of Mn2+ ion into B-QDs not only enhances fluorescence efficiency but also provides favorable sites within the QDs, expanding their potential applications in analytical chemistry. The blue fluorescent Mn2+ @B-QDs exhibited excellent performance for the selective recognition of L-thyroxine via a dynamic quenching mechanism. Under ideal conditions, a good linear relation was observed between the fluorescence emission intensity ratio of Mn2+@B-QDs and the concentration of L-thyroxine in the range of 0.125–5 μM, with a lower detection limit of 59.86 nM. The Mn2+@B-QDs exhibited the negligible cytotoxicity against A549 lung cancer cell lines and demonstrated good biocompatibility toward Saccharomyces cerevisiae cells.

Morphology of dissipative structures formed during the high-temperature synthesis of the MgB2 compound

The interaction of components during high-temperature annealing of compressed magnesium and boron powders in the technologies for obtaining the superconducting compound MgB2 in works using standard synthesis technology and hot gas-static pressing technology is considered. The effect of the kinetics of crystal growth and diffusion of components released at the interface on the morphology of dissipative structures formed during phase transformation is studied in a computer model of crystallization of a binary alloy. The conditions and mechanism of formation of “dendrite-like” and “layered” structures arising during crystallization of MgB2 from magnesium melt (Mg –%B) are analyzed. It is shown that the application of pressure during the synthesis of the compound makes it possible to control the morphology of the resulting dissipative structures that determine the degree of development of porosity and liquation heterogeneity of the composition in a massive superconductor.

Combustion and mechanical properties enhancement strategy based on stearic acid surface activated boron powders

Boric acid and other impurities on the surface of boron (B) particles can interact with hydroxyl-terminated polybutadiene (HTPB), weakening the mechanical properties and energy release efficiency of boron-based solid rocket propellants. SA@B composite particles were created by coating stearic acid (SA) on the surface of B particles through solvent evaporation-induced self-assembly. The study investigated the impact of SA coating on the combustion performance of B particles and the mechanical properties of HTPB matrix composites. The results showed that the SA coating enhanced the oxidation efficiency of B particles in air. The combustion heat of SA@B composite particles is 30.29 MJ/g, about 50% higher than that of B particles. During the combustion of SA@B composite particles, fewer molten solid particles surround the flame, which enhances the stability of the combustion process of the B particles. Furthermore, the SA coating effectively enhanced the dispersion of B particles in HTPB. At a stretching speed of 100 mm/min, the tensile strength of the SA@B/HTPB composite materials is higher than that of the B/HTPB composite materials. Moreover, when the mass loading of the SA@B composite particles reaches 50 wt%, the tensile strength of SA@B/HTPB composite materials is 2.46 MPa. Activating the surface of boron particles with SA can significantly improve their compatibility with HTPB, which is crucial for the stable storage of boron-based solid rocket propellants.

The synergy of polyvinylidene fluoride and CuO to enhance the combustion of boron powder

The synergy of polyvinylidene fluoride and CuO to enhance the combustion of boron powder

Insight into the formation mechanism of oxidation layer on the amorphous boron nanocluster surface

Boron (B) powder with a high-energy density can enhance the energy of propellants. It has two different forms, namely amorphous B and crystalline B, which have different behaviors during the oxidation. Especially, the oxidation layer (OL) on its surface inhibits the ignition and combustion (IC). To comprehend the formation of OL on the amorphous B nanocluster (BNC) and elucidate its oxidation mechanism, the investigation was conducted on the oxidation of amorphous BNC at various oxygen contents and temperatures (300–1900 K). An analysis of the initial oxidation products (OP), the formation process of the oxidation layer, the reaction path, and the oxidation rate were encompassed and the microscopic oxidation mechanism that cannot be observed experimentally was revealed. The morphology of B (crystalline or amorphous B) does not significantly affect the OP and the thickness of OL. The initial OP of amorphous BNC are BO2 rather than B2O3, and the ultimate OP consist of BO2, BO, and polymer BmOn (m≠1). The oxidation layer on the B surface exhibits a relatively thin thickness. The oxidation rates of two different types of B both follow a parabolic law. The atomic structure of B cluster has an important influence on the reactivity of B. The oxidation rate is influenced by both the surface structure and the oxygen content of amorphous BNC. Based on the above research, a novel oxidation mechanism of amorphous BNC was proposed.

Boriding of Ti-xNb alloys: Influence of Nb on the features of boride layer

In this study, Ti-xNb (x = 0–40 wt%) alloys produced by the powder metallurgy were borided with the aim of clarifying the effect of Nb on the structural and mechanical properties of the boride layer. After smearing the paste prepared from nano boron powder on the surfaces of the alloys, boriding was conducted at three different temperatures (900, 1000 and 1100 °C) for 8 h in a vacuum atmosphere. Unlike those formed at 900 °C, boriding temperatures of 1000 and 1100 °C provided thicker and homogenous boride layers. However, the boriding temperature of 1100 °C induced cracking within the boride layer of the Ti40Nb alloy. For these reasons, the optimum boriding temperature was determined as 1000 °C. Increase in the Nb content not only increased the fraction of β-Ti phase in the microstructure of the sintered alloy at the expense of α-Ti, but also induced NbB2 in the structure of the boride layer along with TiB2. While Nb-poor α-Ti grains favoured the growth of TiB2, TiB2·NbB2 mixture preferentially developed over the Nb-rich β-Ti grains. As the result of this, the hardness of the boride layer tended to decrease with increasing Nb content of the substrate. For example, the average hardness of the boride layers formed on Nb-free Ti and Ti40Nb alloy were measured as ∼2674 HV0.025 and ∼ 2460 HV0.025, respectively. But regardless from the hardness, the boride layers provided a good protection for the underlying substrates against dry sliding contact and triggered abrasive wear on the contact surface of the counterface (WC-Co ball). The presence of NbB2 in the boride layer led to a reduction in abrasive wear of the counterface. This finding revealed that in any wear-related application, where borided Ti alloys were intended to be used, it is better to choose high Nb-containing Ti alloys instead of α-Ti to minimize the wear of the tribo-couple via reducing the abrasion at the counter body.

Boron powder injection experiments in WEST with a fully actively cooled, ITER grade, tungsten divertor

Reactor relevant fusion devices will use tungsten (W) for their plasma facing components (PFCs) due to its thermomechanical properties and low tritium retention. However, W introduces high-Z impurities into the plasma, degrading its performance. Different wall conditioning methods have been developed to address this issue, including coating of W PFCs with layers of low-Z material. Wall conditioning by boron (B) powder injection using an impurity powder dropper (IPD) is being studied in WEST. Two series of experiments were conducted since the installation of the new ITER grade full W divertor. During the first series in 2023 ∼ 1 g of B powder was injected in total at a maximum rate of ∼ 58 mg/s, both of which are three times greater than respective values in the initial WEST powder injection experiments. The second series of experiments included injection of B and BN powders for comparison of their effects on plasma performance. The presence of an instantaneous conditioning effect is suggested by visible spectroscopy measurements of low-Z impurity lines and a rollover of total radiated power past an injection rate of ∼ 20 mg/s was observed. Presence of B coating layer formation is supported by the evolution of the average radiance of visible lines of B, W and oxygen (O). To understand B transport, an interpretative modeling workflow is employed, utilizing the SOLEDGE-EIRENE fluid boundary plasma code and the Dust Injection Simulator (DIS) code. Parameters like B perpendicular diffusivity and recycling coefficients are varied to match experimental results to see if the initial assumption of B sticking to the PFCs immediately after the contact with the wall is adequate for correctly modelling its distribution on the PFCs.

Syntheses of AlLB14(L=Li or Na) crystals using alkali fluorides and its properties

AlLB14 (L=Li or Na or K) crystals were grown using LiF or NaF or KF and crystalline boron powders as the starting materials using a high-temperature Al melt at soaking temperature 1573 ∼ 1773 K for a soaking time of 5 h under an Ar atmosphere. AlLiB14 and AlNaB14 crystals were obtained from LiF or NaF and B powders, and the atomic ratios (n=B/L = 2.0 ∼ 4.0) of starting materials. The AlKB14 crystal was not obtained from KF and B powders as starting materials. The micro-Vickers hardness of AlLB14 crystals is 24(±1) GPa for AlLiB14 and 25(±1) GPa for AlNaB14. The oxidation initiation temperature of AlLiB14 was about 815 K, and the peak due to the exothermic reaction was about 960 K for AlLiB14 and about 990 K for AlNaB14. The final oxidation products were Li2B2O4, Al4B2O9, B2O3, and amorphous phases. The values for the electrical resistivity of the AlLB14 compound were 2.4 ∼ 157 Ω·cm.

Effect of powder composition, PTAW parameters on dilution, microstructure and hardness of Ni–Cr–Si–B alloy deposition: Experimental investigation and prediction using machine learning technique

The implementation of hard-facing alloy on the existing materials caters the need for high-performance surfaces in terms of wear and high temperatures. The present research explore the effect of Plasma Transferred Arc Welding (PTAW) parameters and powder composition on dilution, microstructure and hardness of the commonly used hard-facing alloy Ni–Cr–Si–B powder. The hard-facing alloy was deposited with three weight proportions of boron (2.5 %, 3 % and 3.5 %). The statistical-based Grey Relational Analysis (GRA) followed by a Machine Learning Algorithm (MLA) was implemented to identify the ideal parameters and degree of significance of each parameter and for the prediction of the responses. The dilution percentage, microstructure analysis, and phase detection were estimated through elemental analysis, Scanning electron Microscopy (SEM) and X-ray Diffraction Analysis (XRD) respectively. The experimental and modelling results revealed that 400 mm/min of scanning speed, 8 gm/min of powder delivery, 14 mm of stand-off distance, and 120 A of current were the optimal parameters along with 3.5 wt% of boron powder composition to yield a better dilution, microstructure and hardness.

Energetic properties of core–shell B@PVDF/AP composite micro-units prepared by electrostatic spraying technology

In this study, to improve the ignition and combustion performance of fuel boron (B) powder. The core–shell B@ polyvinylidene fluoride (PVDF)/ ammonium perchlorate (AP) composite micro-unit with the effect of erosion activation is successfully prepared by simple and controllable electrostatic spraying technology. The results of morphology and structural composition show that PVDF and AP are tightly wrapped on the surface of B, forming a uniform shell, which effectively prevents moisture absorption and oxidation of B during storage and transportation. The results of the thermal analysis show that the hydrofluoric acid (HF) gas generated by the decomposition of PVDF at about 100 °C in advance has a pre-ignition reaction (PIR) with the boron oxide (B2O3) film on the surface of B. The PIR generates boron fluoride (BF3) gas and breaks the B2O3 film. This reduces the initial oxidation temperature of B by 12.6 % and enhances the oxidation activity of B powder. In addition, the oxygen (O2) released by AP improves the combustion performance of B and strengthens the effect of erosion activation. It is also found that all samples can be successfully ignited and burned continuously, which improves the ignition and combustion performance of B powder. It is worth noting that the ignition delay time of the composite micro-unit sample with the stoichiometric ratio of B/PVDF/AP of 2: 1: 2 can be shortened to 0.454 s at most, which is 17 % lower than that of the physical mixed sample. Moreover, its combustion intensity and flame temperature also reach the best. These results show that the core–shell B@PVDF/AP composite micro-unit provides a great strategy for application in solid propellant and pyrotechnics.

Effects of High Energy Ball Milling on Particle Size and Density of Amorphous Boron Powder

Amorphous boron powder has high mass and bulk calorific values and is used as a high-energy solid fuel in space propellants. However, the low density and large particle size of the amorphous boron powder prepared by the magnesium thermal reduction method results in its small mass share in the propellant, resulting in its low volumetric calorific value. In this study, amorphous boron powder was prepared by dry and wet ball milling with different rotational velocities and ball milling times and ball-to-matter ratios for planetary ball mills. Optimal process parameters for increasing the loose density and decreasing the particle size of amorphous boron powders have been investigated by unidirectional experiments. The results showed that the ball milling medium was ethanol, the rotational speed was 700 r/min, the ball feed ratio was 12%, and the ball milling time was 12 h. Combined with the ultrasonic-assisted acid leaching, the loose density of amorphous boron powders could be increased from 0.3 g/cm3 to more than 0.5 g/cm3, and the particle size of the powders could be reduced from 4 μm to about 1 μm.

Ion temperature and rotation velocity measurements of carbon and boron ions using VUV spectroscopy on EAST.

A space-resolved vacuum ultraviolet spectroscopy is employed to measure impurity emission profiles (500-3200Å) on EAST. This study successfully captures C IV (1548.20 and 1550.77Å) lines emitted from carbon ions and derives ion temperatures using Doppler broadening and a collision model based on their intensity ratios. Both the emission intensity and ion temperature profiles are determined. However, the calculated results reveal a lower temperature of around 10-20eV with the collision model, suggesting a potential need for further correction in subsequent calculations. Furthermore, this study explores relative rotation velocities from the Doppler shift, indicating an increase in toroidal rotation velocity with applied neutral beam injection. The measured results exhibit concordance with the charge exchange recombination spectrometer data. Furthermore, during boron powder dropping discharges on EAST, B II (1623.60, 1623.79, 1623.95, 1624.02, 1624.17, and 1624.38Å) emission lines exhibiting a similar time behavior trend with boron powder injection are identified. Ion temperatures are measured using B II (1362.46Å) through the Doppler broadening method. These techniques hold significant promise for future impurity analysis at the edge of EAST, providing valuable insights into the behavior of carbon and boron ions.

In-situ heteroatoms stabilization of zero-dimensional boron nanospheres for high-energy nanofluid fuels combustion enhancement

Since boron powder has the highest volume energy density, it has long been desired for use as fuel in aerospace and other fields. However, boron has poor ignition performance and low combustion efficiency due to uneven microstructure and oxide layers of boron. Here, we report a facile strategy to prepare zero-dimensional boron nanospheres from micrometer-scale amorphous boron through ultrasound-assisted in-situ stabilization of heteroatoms for inhibition of boron oxide layer by using hexachlorocyclotriphosphazene (HCCP) and 4,4′-sulfonyldiphenol (BPS) polycondensation and carbonization. The diameter of the obtained boron nanospheres was in the range of 500–800 nm, which is the smallest reported diameter of regular boron nanoparticles. The initial reaction temperature of CPZS@B-1.0 decreased from 791.1 to 641.7 °C, and the ignition delay time of 20 wt% CPZS@B-1.0/RP-3 nanofluid fuel decreased to 393 ms. The addition of CPZS@B promoted RP-3 oxidation at both low temperatures (<200 °C) and high temperatures (>200 °C) by in-situ FTIR analysis. Notably, the prepared zero-dimensional nano-boron exhibited removal of surface oxidation and complete combustion degree (from 42.06 % to 80.36 %). This work provides a new method for the preparation of nano-boron and a solution for increasing the fuel energy density of hydrocarbon fuels.

Corrosion and erosion behaviour of TiC-TiB2 reinforced epoxy coatings

ABSTRACT This research investigates the impact of incorporating titanium carbide (TiC) and titanium diboride (TiB2) particles into epoxy coatings to enhance corrosion and erosion resistance. The targeted particles were synthesised by subjecting boron and titanium carbide powders to mechanical alloying for a duration of 20 hours. X-ray diffraction (XRD) analysis confirmed the successful formation of titanium diboride and titanium carbide particles. Subsequently, ceramic particles were integrated into the epoxy at concentrations of 0, 5, 10, and 15 wt.%, and the resultant coatings were applied to steel samples through an immersion method. Electrochemical impedance spectroscopy tests on the samples demonstrated a positive influence of TiC + TiB2 particles on enhancing the corrosion resistance of the coatings, with the 15 wt.% concentration exhibiting superior corrosion resistance compared to other formulations. Employing the Box–Behnken method, 13 samples were designed and subjected to erosion testing. The findings revealed that the coating containing 15 wt.% TiC + TiB2 particles exhibited the lowest erosion rate. Moreover, an increase in the speed and angle during the erosion test correlated with a rise in the erosion rate.

Construction of boron-based double-layer core-shell structure composites and their combustion energy release characteristics

Although boron (B) powder has a high energy density, the high boiling point oxide layer (B2O3) on the surface seriously hinders the combustion of internal B particles, which further limits the use of B powder. In order to solve this issue, polydopamine (PDA) was used as a sandwich layer (sandwich layer used to connect solid-liquid interface) between the original B powder and liquid perfluoropolyether (PFPE), and then a double-layer core-shell structure B@PDA@PFPE was prepared through the electrostatic self-assembly method. Herein, PDA not only helps remove naturally occurring B2O3, but also provides more active sites and improves the reactivity of B and PFPE. The results indicate that the B@PDA@PFPE has excellent combustion flame and energy release characteristics due to the superior dispersion and reactivity of PFPE. Compared to that of the original B powder, the results of thermal decomposition and combustion heat of B@PDA@PFPE with 30%PFPE discloses that the oxidation temperature drops by about 19.5 ℃, the combustion efficiency rises by about 22.3 %, and the flame expansion rate and flame temperature rise by approximately 40 times and 95.6 ℃, respectively. Therefore, the construction of double-layer core-shell structure effectively promotes the combustion of B powder. This work provides a new strategy for the application of B powder.

High-pressure high-temperature synthesis and characterization of B10C

The boron-rich boron carbide materials have been traditionally synthesized by adding boron powder to B4C material and subjecting it to hot pressing sintering for materials composition containing 8.8–20 at. % carbon in boron (composition range of B10.4C to B4C). Our study explores a synthesis route for B10C starting from high-purity boron and carbon and direct conversion under high pressure and high temperature (HPHT) conditions of 2000 °C and 6–8 GPa. Synthesis was verified via x-ray diffraction analysis, showing the conversion of the high-purity boron and carbon powder mixture into a hexagonal B10C structure (R-3m space group) with lattice parameters of a = b = 5.6115 Å and c = 12.197 Å. The concentration of boron was measured through x-ray photoelectron spectroscopy, confirming the B10C ratio. The measured nanoindentation mean hardness of B10C was 40 GPa. Raman spectroscopy of the HPHT synthesized sample shows characteristic vibrational breathing modes of boron icosahedron and an additional intense band at a vibrational frequency of 380 cm−1. This Raman band, which appears notably weaker in earlier studies and B4C samples, is assigned to the linear chain of B–B–B and attributed to the maximal incorporation of boron within the hexagonal structure.

Synergistic Enhancement on Ignition and Combustion Properties of Boron via Viton Core-Shell Coating.

The high gravimetric (58.74 kJ/g) and volumetric (137.45 kJ/cm3) heat values loaded in boron (B) offer significant potential for application in solid propellants and explosives. However, the high melting (2076 °C) and boiling (3927 °C) points of boron powder and the low melting point (450 °C) of oxidation products affect the energy performance and application of boron. Fluorine-containing polymers have high oxidation potential and excellent mechanical properties and can produce expectant gaseous products through the combustion reaction with boron oxide, but research examining the interaction between purified boron powder and fluoropolymers and the optimal selection of the fluoropolymer remains scarce. Herein, the binding energy between typical fluoropolymers [Viton, polyvinylidene fluoride, poly(vinylidene fluoride-co-chlorotrifluoroethylene), and vinylidene fluoride] and boron was calculated via molecular dynamics simulations, which shows that Viton is an appropriate candidate for coating boron powder. In the experiment, The Bw@Viton core-shell composites were prepared using Viton as the coating layer, and boron powder was pre-purified with acetonitrile. Its structure, thermal properties, ignition, and combustion characteristics were then characterized. The results revealed successful removal of the oxide layer, and the hydrophobicity was significantly improved after Viton coating. Purification and coating synergistically enhance the energy release of boron powder, and the composites demonstrated excellent thermal, ignition, and combustion performances. In particular, the heat of oxidation and heat of combustion were increased by 26.6 and 32.7%, respectively. The ignition delay time was reduced by 53.2% compared to raw boron. A prospective reaction mechanism between boron and Viton is thus proposed.

Evaluation of the Combustion Properties and Catalytic Activity of MgAlB Energetic Ternary Particles

ABSTRACT Boron powder possesses significant potential for use as a combustible agent in energetic materials, owing to its superior combustion thermodynamic properties. However, the powder’s tendency to form an oxide layer on its surface results in delayed ignition, reduced combustion efficiency, and compromised energy advantage. To enhance the ignition and combustion properties of boron powder, we prepared boron-based energetic composites containing flammable metals (MgxAl1-xB2) through high-temperature sintering. These were then characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS). The combustion heat of these alloy powders were measured using an oxygen bomb calorimeter, while their catalytic performance on the thermal decomposition of ammonium perchlorate (AP) was analyzed using differential scanning calorimetry (DSC) and differential thermal analysis (DTA). The results indicate that compared with boron, the MgxAl1-xB2 powders are more flammable, require less oxygen, exhibit a higher combustion efficiency and exothermic advantage. Especially, the Mg0.9Al0.1B2 and MgB2 alloy exhibit optimal combustion heat values of 39,094.92 and 37,693.90 J·g−1, respectively. They significantly enhance the thermal decomposition of AP and reduce the activation energy by over 20%.

The Structural Examination of Fe/(Cu/Nb)/MgB2 Multifilament Wires During Cold Forming Process

In this study, we have successfully produced a Fe-sheathed 6+1 multifilament wire using Cu/Nb/MgB2 monocore wires. The mono filament wire was prepared using Mg+2B powder mixture by powder-in-tube method without any intermediate heat treatment. The powder mixture of the amorphous nano boron (PVZ Nano Boron, purity of 98.5%, particle sizes &lt; 250 nm) and high purity Mg powder (PVZ Mg, purity of 99%, particle size 74µm) were used. The multifilament wire was produced using groove rolling and cold drawing machines. The geometrical form of the filaments was examined using wire pieces taken from the wire at different steps throughout the production process. Finally, the multifilament wires produced in two different diameters of 1.02 mm and 0.82 mm were investigated in terms of filament uniformity, crack formation, surface roughness, and electrical transport properties. The structural examination was done on Nb filaments after the Fe and Cu sheaths were etched using HCl and HNO3 solution. The I – V measurements of the multifilament wires heat treated at 650 °C for 15, 30, 45, 60, and 240 minutes, and 700 °C for 60 minutes were carried out for the applied current up to 1 A at 25 K under various external magnetic field.