Increasing Boron Content Research Articles

Developed borated austenitic stainless steel alloys as nuclear reactor control rods

Modified austenitic stainless steel alloys reinforced with B and B/Ti were fabricated and their suitability as nuclear reactor control rods was tested. A standard stainless steel AISI 316L was used as a base alloy and inlaid by 0.58 wt% of B (SSB). The structural examination of the modified SSB stainless steel, which was conducted through the Schaeffler diagram, optical micrographs (OM), and X-ray diffraction (XRD) patterns had referred to the domination of the austenite phase with the appearance of boride (M2B) and carboborides (M23X6) phases along the grain boundaries. Mechanically, an augmentation in the hardness, yield strength (YS), and ultimate tensile strength (UTS) values was observed with the incorporation of B into the AISI 316L stainless steel. However, the addition of B led to a reduction in the values of elongation (El), reduction area (RD), and impact energy. Then, the SSB stainless steel was reinforced by 0.33 wt% of Ti (SSTiB1). The structural examination showed the formation of M2B, M23X6, TiC, TiN, and TiB2 phases along the grain boundaries of the austenite matrix as well as little ferrite phases. Ti led to a significant increase in hardness, YS, UTS, El, RD, and impact energy of the SSB steel. Finally, a further addition of B and Ti (1.13 & 1.77 wt% of B & Ti, SSTiB2) was tested, as this increase led to the more enhancement of hardness, YS, UTS, and impact energy but reduced the El slightly. Due to the high slow neutrons absorption cross-section of B, the slow neutrons attenuation ability of the modified stainless steel increased effectively with increasing boron concentrations. The obtained distinctive mechanical properties and high attenuation efficiency of slow neutrons of the produced SSBTi2 stainless steel, make it a suitable choice for use as control rods in nuclear reactors.

Effects of boron, Hf and Ta content on boride morphology and microstructure of β-solidified γ-TiAl alloys

Boron is the most commonly used grain refining element in γ-TiAl alloys and the morphology of the borides has a significant influence on the room temperature plasticity of γ-TiAl alloys. In this paper, the effect of boron, Hf and Ta content on boride morphology and microstructure of a γ-TiAl alloy (Ti-43.5Al–4Nb–1Mo-0.5B) were investigated. The boride morphology transitions from flat to curved as boron content increases from 0.5% to 0.8%. With a further increase in boron content, the curved borides change into short rod-like and granular. Boride morphology changes from flat to curved When Hf is added. Conversely, when Ta is added, the length and width of the borides become smaller and dendritic borides with complex morphology appear. The combination of solid solution strengthening (boron, Hf and Ta), precipitation strengthening (borides) and grain refining increases the alloy's hardness. Furthermore, the flat borides are rich in Nb and Ta, whereas the curved borides are rich in Al. The present study shows that the addition of Ta can refine the size of borides, which may have a positive effect on improving the room temperature properties of the γ-TiAl alloy.

Two Fe-Zr-B-Cu Nanocrystalline Magnetic Alloys Produced by Mechanical Alloying Technique

Fe-rich soft magnetic alloys are candidates for applications as magnetic sensors and actuators. Spring magnets can be obtained when these alloys are added to hard magnetic compounds. In this work, two nanocrystalline Fe-Zr-B-Cu alloys are produced by mechanical alloying, MA. The increase in boron content favours the reduction of the crystalline size. Thermal analysis (by differential scanning calorimetry) shows that, in the temperature range compressed between 450 and 650 K, wide exothermic processes take place, which are associated with the relaxation of the tensions of the alloys produced by MA. At high temperatures, a main crystallisation peak is found. A Kissinger and an isoconversional method were used to determine the apparent activation of the exothermic processes. The values are compared with those found in the scientific literature. Likewise, adapted thermogravimetry allowed for the determination of the Curie temperature. The functional response has been analysed by hysteresis loop cycles. According to the composition, the decrease of the Fe/B ratio diminishes the soft magnetic behaviour.

تأثير الرش بالسكريات الكحولية والبورون في بعض مؤشرات النمو والإزهار والإنتاج لنبات الفراولة (Fragaria x ananassa Duch) صنف أوزوغراند (Oso grande)

الملخص نُفذ هذا البحث في كلية الزراعة، في جامعة دمشق (دمشق/ سورية) خلال عام 2021، بهدف دراسة تأثير الرش بالبورون (حمض البوريك) (0, 50, 100 ppm) والسكريات الكحولية (السوربيتول والمانيتول) بثلاثة تراكيز (10، 20، 30 غ/ل) في نمو وإنتاج نبات الفراولة ونوعية ثماره (Fragaria × ananassa Duch) صنف أوزوغراند. لوحظ من النتائج أن الرش بالسكريات الكحولية (السوربيتول، والمانيتول) يحسّن نمو وإنتاج نبات الفراولة، وكذلك نوعية ثماره؛ فازدادت قيم المؤشرات المدروسة بزيادة التركيز، فوصل عدد الأوراق (19.06، 21.62، 23.95 ورقة/نبات) عند رش النبات بالسوربيتول (19.78، 22.57، 25.13 ورقة/نبات) والمانيتول (10، 20، 30 غ/ل، على الترتيب) مقارنة بالشاهد 15.27 ورقة/نبات. تأثر الإنتاج الكلي إيجابياً عند الرش بالمانيتول تركيز 30 غ/ل (556.29 غ/ نبات)، في حين وصل إلى (465.48 غ/ نبات) للسوربيتول بتركيز 30 غ/ل، مقارنةً بالشاهد. تحسنت نوعية الثمار بزيادة تركيز البورون (القيمة الأعلى للمواد الصلبة الذائبة (8.69%) سُجّلت عند التركيز (100 ppm) من البورون، مقارنة بالشاهد (7.59%). تفوق التفاعل بين (المانيتول 30غ/ل، والبورون 100 ppm) معنوياً في أغلب المؤشرات المدروسة وعلى نحو ملحوظ، مثل عدد الأوراق (29.06) ورقة/ نبات، والإنتاج الكلي (712.03غ)، وكمية فيتامين (C) (52.03 مغ/100غ وزن طازج)، مقارنةً بالشاهد 0غ/ل. أظهرت نتائجنا التأثير الإيجابي للرش الورقي بالسكريات الكحولية والبورون في نبات الفراولة، فينصح باستخدام التركيز (30غ/ل) للسكريات الكحولية و(100 ppm) للبورون؛ للتفوق المعنوي الذي حققاه مقارنةً بشكل مستقل ببقية التراكيز، ويفضل الرش بالمانيتول لأنه سجّل قيماً أكثر ارتفاعاً مقارنةً بالسورية.

Boron-induced magneto-optical Kerr spectra and dielectric tensors in ferrimagnetic (Mn4N)B antiperovskite thin films

Boron-induced electronic states were investigated via a combination of polar magneto-optical Kerr effect (p-MOKE) spectroscopy and spectroscopic ellipsometry for one of the antiperovskite nitrides, Mn4N. The boron content in the Mn4N film varied from 0 to 4.3 at.%, for which the crystal structure was maintained. The amplitude of p-MOKE spectra and the diagonal and off-diagonal dielectric tensors decreased with increasing boron content, which is in agreement with the magnetic properties such as magnetic anisotropy and saturation magnetization. These results were related to the lattice expansion and displacement of the charge density in the Mn4N by boron doping. However, the peak energy of the Lorentz oscillator in the diagonal elements of dielectric tensors suggests that a dominant inter-band transition was independent of boron content.

Polyborosilazane with Broadly Tunable Boron Content for SiBCN Ceramics.

The high-temperature durability of SiBCN ceramics is significantly influenced by the boron concentration and synthesis methods. Although single-source synthetic routes allow one to obtain homogeneous ceramics at the atomic level, the content of the boron element therein is limited by borane (BH3). In this study, the synthesis of carborane-substituted polyborosilazanes was performed via a simple one-pot reaction of polysilazanes with alkyne bonds on the main chain and decaborododecahydrodiacetonitrile complexes with different molar ratios. This enabled one to vary the boron content from ∼0 to 40.00 wt %. The ceramic yields were in the range of 50.92-90.81 wt %. Independently of the borane concentration, SiBCN ceramics started to crystallize at 1200 °C, and B4C appeared as a new crystalline phase with increasing boron content. The introduction of boron inhibited the crystallization of Si3N4 and increased the crystallization temperature of SiC. The presence of the B4C phase improved both thermal stability and functional properties such as neutron-shielding characteristics of the ceramics. Therefore, this research opens up new prospects for the design of novel polyborosilanzes with great application potential.

Botanical and physiological parameters response of black bean (Phaseolus vulgaris L.) cultivars under increasing boron concentrations

Argentina is one of the five leading exporters of common bean (Phaseolus vulgaris L.) worldwide. Although common bean has been characterized as sensitive to boron toxicity, its production is often subjected to high boron concentrations. The aim of this study was to provide detailed information on the impact of increasing boron concentrations (0.5–8.0 mg L−1) on germination, growth, and root anatomy of two black bean cultivars (Leales 24 and Uirapurú) frequently produced in Argentina. Standard germination assays and pot greenhouse experiments were conducted. Radicles obtained in germination assays were used to make cross sections, which were analyzed under the microscope to identify anatomical alterations. Increasing boron concentrations had no effect on germination variables. In contrast, most of the growth variables analyzed (height, leaf area, fresh and dry weight, and water content) showed a steady decrease for boron concentrations above 1.0 mg L−1. Tissue boron concentrations showed an increase when boron concentrations increased. At the microscopic level, there seemed to be a decreasing trend in xylem vessel diameter. Our results suggest that boron concentrations above 1.0 and 2.0 mg L−1 may cause considerable growth and yield decreases in Uirapurú and Leales 24, respectively, thus affecting Argentinian bean production. Additionally, our results suggest that Leales 24 is moderately sensitive to boron toxicity and is best adapted for production in areas with higher boron concentrations. These findings highlight the importance of evaluating boron concentrations in soils and irrigation water in agricultural areas, and selecting cultivars best adapted to local conditions as tools for obtaining higher yields.

Tribo-mechanical behaviour of electroless Ni-B-Mo coatings with varying bath composition

Ni-B-Mo alloy coating layers are developed on steel substrates with various coating bath compositions to investigate the significance of bath parameters on coating characteristics. The as-deposited coatings are characterized based on surface roughness, coating thickness, surface morphology, and phase structure through Surface Roughness Tester, Scanning Electron Microscopy (SEM), and x-ray Diffraction (XRD), respectively. Tribological behaviour of the coated layers is investigated through a pin-on-disc multi-tribo tester under dry condition. Surface hardness and elastic modulus are measured through nano-indentation tests. The scratch-hardness of the coatings is measured using a micro-scratch tester. Coating characteristics are determined and the significance of each coating bath parameter is analysed. It is found that the coating thickness increases with bath parameter concentration level due to increase in borohydride concentration. The increase in molybdenum concentration increases the surface roughness (Ra) from 0.28 μm to 1.05 μm and forms coarse grained surface morphology with some visible cracks leading to increase in COF value from 0.24 to 0.77. Nano-hardness and scratch hardness are found to decrease with the addition of molybdenum into the Ni-B matrix though nano-hardness (Hv) value increases from its minimum value of 530 to 971 due to the increase in boron concentration. The elastic modulus value is found to vary from 83 GPa to 197 GPa but no such specific trend may be observed with the variation of bath composition.

Ignition and combustion characteristics of boron-based nanofluid fuel

With its high gravimetric and volumetric heat value, boron-based nanofluid fuel is potentially well suited for future high-energy propulsion systems. In this experimental study, we investigate the ignition and combustion of boron-based nanofluid fuel, with a focus on the effects of oleic acid (OA) concentration (0 to 10 wt.%), boron particle concentration (2.5 to 20 wt.%), and boron particle size (300 nm to 13 µm). Thermogravimetry−differential scanning calorimetry and laser ignition tests reveal that adding boron nanoparticles to a fuel can improve its combustion intensity, but without much affecting the oxidation and ignition characteristics, primarily because of agglomeration and thicker oxide layer properties relative to boron microparticles. Pure kerosene droplets are found to undergo pre-ignition heating and classic combustion, whereas OA or boron addition promotes puffing and micro-explosions, accelerating the classic combustion process. The co-existence of OA and boron is found to lead to more frequent and stronger disintegration of the nanofluid fuel droplet. The ignition delay reaches 156 ms with only 2.5 wt.% OA inclusion, compared to just 73 ms for pure kerosene. Both the ignition delay and combustion rate increase, while the solid residual decreases owing to enhanced micro-explosions as the OA concentration increases. Unlike OA, boron addition promotes ignition, with 2.5 wt.% boron yielding an ignition delay reduction of 24 ms, but this effect weakens with increasing boron concentration. The combustion rate is found to be relatively insensitive to boron addition. Although the particle size affects the ignition and combustion performance of boron powder, its effect on the combustion of the nanofluid fuel droplet is, under the present test conditions, relatively weak. Finally, a phenomenological model is presented to capture the ignition and combustion of a boron-based nanofluid fuel droplet. The predicted ignition delay and combustion rate are found to be within 7.15% of their experimental values. This study contributes to an improved understanding of boron ignition and combustion in high-energy liquid fuel systems.

Effect of Boron on the Microstructure, Superplastic Behavior, and Mechanical Properties of Ti-4Al-3Mo-1V Alloy.

The decrease of superplastic forming temperature and improvement of post-forming mechanical properties are important issues for titanium-based alloys. Ultrafine-grained and homogeneous microstructure are required to improve both processing and mechanical properties. This study focuses on the influence of 0.01-2 wt.% B (boron) on the microstructure and properties of Ti-4Al-3Mo-1V (wt.%) alloys. The microstructure evolution, superplasticity, and room temperature mechanical properties of boron-free and boron-modified alloys were investigated using light optical microscopy, scanning electron microscopy, electron backscatter diffraction, X-ray diffraction analysis, and uniaxial tensile tests. A trace addition of 0.01 to 0.1 wt.% B significantly refined prior β-grains and improved superplasticity. Alloys with minor B and B-free alloy exhibited similar superplastic elongations of 400-1000% in a temperature range of 700-875 °C and strain rate sensitivity coefficient m of 0.4-0.5. Along with this, a trace boron addition provided a stable flow and effectively reduced flow stress values, especially at low temperatures, that was explained by the acceleration of the recrystallization and globularization of the microstructure at the initial stage of superplastic deformation. Recrystallization-induced decrease in yield strength from 770 MPa to 680 MPa was observed with an increase in boron content from 0 to 0.1%. Post-forming heat treatment, including quenching and ageing, increased strength characteristics of the alloys with 0.01 and 0.1% boron by 90-140 MPa and insignificantly decreased ductility. Alloys with 1-2% B exhibited an opposite behavior. For the high-boron alloys, the refinement effect of the prior β-grains was not detected. A high fraction of borides of ~5-11% deteriorated the superplastic properties and drastically decreased ductility at room temperature. The alloy with 2% B demonstrated non-superplastic behavior and low level of strength properties; meanwhile, the alloy with 1% B exhibited superplasticity at 875 °C with elongation of ~500%, post-forming yield strength of 830 MPa, and ultimate tensile strength of 1020 MPa at room temperature. The differences between minor boron and high boron influence on the grain structure and properties were discussed and the mechanisms of the boron influence were suggested.

Plasmon energy and microhardness of BxAl1-xSb alloys: semi-empirical prediction

Based on the reflective index reported in the literature, the present work aims to investigate the plasmon energy, the microhardness and the homopolar band gap energy of BxAl1-xSb ternary semiconducting alloys as a function of boron concentration x in the range 0 –1. We found that both the plasmon energy and the microhardness of BxAl1-xSb alloys change gradually but not monotonically with increasing of boron concentration x from 0 to 1, while the homopolar band gap energy increases monotonically with enhancing of x. We emphasize that a boron concentration x dependent plasmon energy and microhardness between 0 and 1 is extremely unusual behavior for BxAl1-xSb alloys. Normally, both plasmon energy and the microhardness monotonically increase with increasing boron concentration x as it was mentioned in the literature. The plasmon energy of AlSb and BSb was found to be 16.14 and 15.58 eV, respectively. Our value (16.14 eV) of the plasmon energy for AlSb compound is higher than the result (13.8 eV) reported by Böer and Pohl. The minimum of the plasmon energy was found to be 14.4 eV for both B0.5Al0.5Sb and B0.625Al0.375Sb alloys. The microhardness of AlSb was found at around 7.56 GPa, while that of BSb was found to be 6.51 GPa. Similar to the plasmon energy, the minimum value of the microhardness was found to be 4.45 GPa for both B0.5Al0.5Sb and B0.625Al0.375Sb alloys.

Stable Rb-B compounds under high pressure

As a frontier issue of physics and material, the structures and related properties of borides have been extensively investigated in fundamental science. The search for pressure-induced stable compounds has become a feasible approach to acquire borides that are inaccessible at atmospheric pressure. Combined with state-of-the-art swarm intelligence structure prediction and first-principles calculations, we systematically explored the Rb-B system and uncovered a series of unprecedented RbB, ${\mathrm{Rb}}_{2}{\mathrm{B}}_{3}$, ${\mathrm{RbB}}_{3}$, ${\mathrm{RbB}}_{6}$, ${\mathrm{RbB}}_{8}$, and ${\mathrm{RbB}}_{10}$ under high pressure. It is found that the catenation of boron evolves from linear chain to layered sheets, clusterlike units, and further to three-dimensional tunnel structures with increasing boron content. Among them, ${\mathrm{RbB}}_{6}$ and ${\mathrm{RbB}}_{8}$ are expected phonon-mediated superconductors with ${T}_{c}$ of \ensuremath{\sim}12 K and superhard material with a hardness of \ensuremath{\sim}37 GPa at ambient pressure, respectively. Additionally, ${\mathrm{RbB}}_{8}$ is a suitable precursor for obtaining the superconducting $o\text{\ensuremath{-}}{\mathrm{B}}_{16}$ boron allotrope by removing Rb due to its better stability than isomorphic ${\mathrm{SrB}}_{8}$. The current results provide insights into the design of unforeseen borides and illustrate intriguing B-B bonding features originating from Rb \ensuremath{\rightarrow} B charge transfer under pressures.

Effect of boron on the microstructural evolution and wear resistance of high-hardness Fe-based alloy coatings prepared by laser cladding

One of the primary failure modes of 45 steel is severe surface wear, which significantly raises its application cost. In order to improve the wear resistance, high-hardness Fe-based alloy coatings with varying boron contents were prepared on 45 steel substrates by preplaced-powder laser cladding in this study. The effect of boron content on the phase composition and microstructural evolution of the coatings were systematically studied. The proportion, morphology, and distribution characteristics of boride phases in the coatings were discussed in detail. The results demonstrated that the Fe-based alloy coatings with different boron contents were composed of α-Fe, Cr7C3, and Fe2B phases. The boron content had a significant influence on the morphology and proportion of the boride phases. With the increase of boron content, the proportion of boride phases gradually increased and the morphology transition was reticular → cluster-shape → long strip-shape → plate-shape. The composition analysis revealed that the boride was Cr-rich Fe2B phase and the content of Cr in the borides increased with the boron content of the coating. The addition of boron could effectively improve the hardness and wear resistance of the Fe-based coatings, which could be attributed to the boride hard phases in the microstructures. The coating with 6.0 wt% B exhibited the highest microhardness and least amount of wear loss. The wear mechanism of the coating with different boron contents was also discussed.

Neutron-Absorption Properties of B/Cu Composites

Copper has high electrical and thermal conductivity, which is frequently employed in structural and functional materials. In this research, powder metallurgy was used to incorporate boron nanosheets into metal matrix composites to create boron dispersion-enhanced copper matrix composites. The neutron-absorption characteristics of composite materials were investigated, as well as the link between neutron-absorption cross-section and neutron energy. The results told us that the morphology of the second phase on the particle surface is closely related to the size of Cu-B particles, copper and boron correspond atomically to each other on the interface without dislocation or lattice distortion, forming a completely coherent interface, and that the neutron absorption cross-section decreases exponentially as neutron energy increases. In low-energy neutrons with energies less than 0.1 eV, the increase of boron content and 10B abundance in Cu-B alloy will enhance the neutron-absorption capacity of the alloy. Boron dispersion-strengthened copper matrix composites have good neutron-absorption capacity, and the microstructure and size of boron do not affect the neutron-absorption performance of composites with the same content of boron. The hardness of the B-dispersion-strengthened Cu matrix composite obtained by nanoindentation test is about 3.04 GPa. Copper matrix composites with boron dispersion reinforcement exhibit high hardness and neutron-absorption characteristics.

Effect of Amorphous Boron on the Microstructure and Corrosion Properties of Ni-W Coatings

In this study, a nickel-tungsten/amorphous boron composite coating (Ni-W/B) was successfully deposited on carbon steel using the electrodeposition method. Electrodeposition was performed by dispersing varying quantities of amorphous boron (0, 0.5, 1, and 3 g/L) particles in a Ni-W electrolytic bath. The microstructure and morphology of composite coatings were characterized by scanning electron microscope (SEM). The electrochemical properties of the Ni-W alloy and Ni-W/B composite coatings were studied using electrochemical impedance spectroscopy (EIS), polarization curves, and immersion testing. It was found that the addition of amorphous boron particles to Ni-W coatings can significantly smooth the modified composite coatings and improve the corrosion resistance, probably by changing the corrosion from pitting to uniform corrosion with increasing boron content. The boron concentration of 0.5 g/L in the bath provided the highest corrosion resistance among all the modified coatings.

Enhancement of elastic properties and surface plasmon resonance with the addition of boron oxide to the ZnO−SiO2 glass system

Glass substrates, with their ultrasonic and enhanced Raman signals, are ever-demanding for medical applications. This paper reports the effect of boron addition to the enhancement of the elastic properties and Raman shifting in the Surface Plasmon Resonance results for the zinc borosilicate glass substrate that can be used for optical biosensor applications. Such glasses were prepared by melt–the quenching method and characterized using a densimeter, X-ray diffraction measurement, Fourier transforms infrared spectroscopy, ultrasonic, and surface plasmon resonance spectroscopy. Results from the current study demonstrated how the composition of the glass influences the physical and elastic moduli of the boron-doped zinc silicate series. The physical characteristics of the zinc silicate glasses were predicted to alter significantly after adding boron as a modifier. The glass density decreased from 3392 to 2983 kg/m3 as the percentage of boron increased from 0.10 to 0.20 wt.%, then increased to 3191 kg/m3 at 0.30 wt.%. The X-ray diffraction and Fourier transforms infrared spectroscopy techniques verified the amorphous glass phase. The ultrasonic method determined the glass's ultrasonic longitudinal and shear velocity at a 5 MHz resounding recurrence at room temperature to study elastic moduli. When boron content is added, the longitudinal, Young, shear, and bulk moduli exhibit a decreasing and increasing trend. As the boron content increases and behaves as a modifier, the number of non-bridging oxygen will increase, which will cause the glass network to expand. In addition, the increase in Eopt occurs from 3.4883 to 3.4331 because the sample has a higher number of non-bridging oxygen. The shift for Otto configuration of the SPR results occurs with the increase of boron concentration. The fabricated glass can potentially be used to construct an integrated silicon-based glass substrate for an optical sensor.

Evidence of ferromagnetism in boron doped graphene oxide synthesized by hydrothermal method

[Enhancing graphene's ferromagnetic properties is important for a variety of applications, including spintronics, magnetic memory, and other electromagnetic devices. A modified version of Hummer's approach was used to synthesize reduced graphene oxide. Boron-doped graphene oxide with different dopant concentrations (1,3,5 and 7 wt%) has been synthesised using the hydrothermal method. Powder X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy are used to characterize the structure. The results of the XRD analysis show that reduced graphene oxide and boron-doped graphene oxide have been formed. The existence of boron atoms at the carbon lattice has been confirmed by observation of the FTIR and Raman spectra. The presence of dopant concentrations was calculated using X-ray photo electron spectroscopy. To further analyze the magnetic characteristics of doped samples, vibrating sample magnetometer investigations are used. The samples shows significant ferromagnetism at room temperature. It has been found that the saturation magnetization(Ms) increases with an increase in boron content. For the sample with the highest boron content, the saturation magnetization(Ms) reaches 0.03 emu/g at room temperature and the coercive force(Hc) reaches 73.9 Oe. Due to the improvement in the ferromagnetic property of boron doped graphene, these materials can be used for nonmagnetic applications and other electromagnetic devices.]

Electrical and Optical Properties of Boron Doped Zinc Oxide Thin-film Deposited by Metal-organic Chemical Vapour Deposition for Photovoltaic Application

Globally, there is a high demand for clean, sustainable and renewable energy for domestic and industrial use. Conventional photovoltaic cell technology relies heavily on crystalline silicon wafers which render silicon-based solar cells expensive due to the initial cost of production and required complex deposition methods. Due to these challenges, great research interest is now directed towards thin-film solar cells. In this work, the metal-organic chemical vapour deposition (CVD) method was chosen in the preparation of boron-doped zinc oxide (ZnO: B) thin film onto a glass slide substrate. The prepared ZnO: B thin films were characterized and optimized as a window layer for solar light trapping. The transmittance of the ZnO: B films varied between 70% and 81% for boron concentration ranging from 0.0 M to 0.06 M. With the increase in boron concentration, bandgap and resistivity of the ZnO: B varied from 2.96 to 3.72 eV and 120 Ω-cm to 58 Ω-cm, respectively. Based on the results obtained, we believe that ZnO: B is suitable as a window layer for solar light trapping in the fabrication of a photovoltaic cell.

Influence of boron on the stress-rupture behavior of an additively manufactured Hastelloy X

The influence of minor additions of boron and the as-built (AB) microstructure on stress-rupture behavior of a modified crack-free Hastelloy X fabricated by laser powder bed fusion (L-PBF) was investigated. Isothermal stress rupture tests were performed at 816 °C under a static tensile load of 103 MPa. Micro-void formation in the vicinity of carbide precipitates and their coalescence was only observed at chevron-like high-angle grain boundaries, characteristic of L-PBF process. These grain boundaries, laying on the planes with maximum resolved shear stress with respect to the loading direction, directly governed the intergranular crack propagation. In view of the fracture mechanism and the time to rupture, increasing boron content significantly improves time-to-rupture through a diffusion-controlled mechanism by hindering the carbon diffusion to the grain boundaries. Adequate additions of boron (>10 ppm) guarantee the stress-rupture properties (strength) of the AB components without the need for additional post-thermal treatments. Further increase in boron content (i.e., 30 ppm), led to about five times increase in time to rupture (500 h vs. 110 h), and significantly improved creep elongation (30% vs. 9%) compared with the low boron alloy.

Fabrication and Characterization of In Situ Ti-6Al-4V/TiB Composites by the Hot-Pressing Method using Recycled Metal Chips

In this study, a Ti-6Al-4V matrix composite reinforced with in situ synthesized TiB whiskers has been successfully produced from wasted chips by a cost-effective powder metallurgy route combining rapid heating and hot pressing. The effect of boron powder addition (1 vol.%, 3 vol.%, 5 vol.%, and 7 vol.%) on phase constituents, microstructures, and mechanical properties of the fabricated composites was investigated. Additionally, the effect of two different post-heat treatments on the 3 vol.% boron-containing composites was also explored. The results show that the ultimate tensile strength (UTS) and yield strength (YS) of the composite first increase when the content of boron is less than 3 vol.%, and then start to decrease with the further increase of boron content. The TiB reinforcement layers change from discontinuous to quasi-continuous and then to continuous with increasing boron content, which is attributed to a higher fraction of agglomerated TiB reinforcement phases. The composites with 1 vol.% (UTS of 1085 MPa, strain to fracture of 5.83%) and 3 vol.% (UTS of 1127 MPa, strain to fracture of 3.98%) boron powder addition show optimized tensile properties. The mechanical properties of 3 vol.% boron-containing composites are not significantly improved after heat treatment. Our experimental results demonstrate the feasibility of fabricating low-cost, high-performance titanium alloy matrix composites from Ti-6Al-4V machining chips. It can serve as a promising and cost-effective method to directly utilize Ti-6Al-4V chips to fabricate strong and ductile Ti-6Al-4V composites for niche applications.