Effect Of Boron Content Research Articles

Effect of Boron Content on Microstructure, Mechanical Properties, and Oxidation Resistance of Mo-Si-B Composites

Mo-Si-B composites with boron content from 0 to 8 wt.% were prepared by spark plasma sintering using Mo, Si, and B elemental powders. The effects of boron content on the phase composition, mechanical properties, and high-temperature oxidation resistance of the Mo-Si-B composites were investigated. The results show the evolution of the major phase constitution of the composites with increasing boron content is in the following sequence: (MoSi2, Mo5Si3) → (MoSi2, Mo5Si3, Mo5SiB2) → (MoSi2, MoB) → (MoSi2, MoB, MoB2). As the boron content increases, both the hardness and flexural strength of the composites increases, but the fracture toughness of the composites gradually decreases. The strengthening mechanisms for the composites are second-phase strengthening and grain refinement strengthening. However, the formation of brittle phases, i.e., Mo5SiB2, MoB, and MoB2, reduces the toughness of the composites. In addition, since a dense barrier layer of SiO2-B2O3 formed on the surface of the composites inhibits the inward diffusion of oxygen, B-doped Mo-Si-B exhibits better oxidation resistance compared with non-doped composites.

Microstructures and high-temperature mechanical properties of a directionally solidified Ni-based superalloy: Influence of boron content

The effects of boron content on the microstructure and mechanical properties of a directionally solidified Ni-based superalloy were investigated. The increase of boron content significantly increases the amount of γ/γ′ eutectic, impels the formation of multi-phase eutectic-like constituent, and promotes the morphological transformation of MC carbides from rod-like to blocky. After standard heat treatment, the incipient melting occurs in the high boron alloy, which can lower the dissolving temperature of γ/γ′ eutectic. With increasing boron content, the volume fraction of secondary γ′ phase decreases significantly and the homogeneity and alignment of secondary γ′ show a decrease, and the tensile strengths at 900 °C decrease slightly mainly due to the strengthening effect of much more tertiary γ′ phases. The wide γ matrix channel facilitates the movement of dislocations, which is somewhat beneficial to the elongation, while the incipiently melted region (IMR), the decreased volume fraction of secondary γ′ phase and the less homogeneity of secondary γ′ phase are rather harmful to the elongation. Consequently, the elongation is drastically reduced. The existence of a large amount of IMRs is principally responsible for the reduction of the stress rupture property. Tertiary γ′ phases re-dissolving in γ matrix channel facilitates the movement of dislocations between large secondary γ′ phases, which is beneficial to the elongation of the alloys. In addition, the IMRs provide masses of crack sources, and consume the precipitation strengthening elements (Ti, Ta) and the solid solution strengthening elements (Cr, W and Mo), which plays the major role in the degradation of the high-temperature tensile or stress rupture properties.

Effect of boron content on microstructure and mechanical properties of Ti50Zr50 alloys

A series of as-cast (Ti50Zr50)100-xBx (x = 0, 2, 4, 6, 8 at.%) alloys were fabricated by vacuum electro-arc melting method. The microstructure and mechanical properties of all as-cast specimens were investigated. Single α′ phase was observed in the Ti50Zr50 alloy. With the adding of B element, the diffraction peaks of TiB and ZrB2 were found. The TiB and ZrB2 intermetallics with a whisker shape were mostly distributed in the prior β grain boundaries. When the addition B content is 4%, the TiB and ZrB2 whiskers is the most smallest. In addition, the microstructures of Ti-Zr-B alloys are obviously refined with the increase B content. It may be attributed to constitutional supercooling caused by boron rejection due to a small amount of solid solubility of boron in titanium and zirconium. The tensile tests indicate that the as-cast (Ti50Zr50)96B4 alloy shows the maximum ultimate tensile strength and yield strength, which increased by 27.9% and 42.3% compared with the Ti50Zr50, respectively. The strengthening mechanisms may be from two aspects of the load transfer and grain refinement. Fracture morphologies show that the brittle fracture becomes dominant in the Ti-Zr-B alloys with the increase of B concentration.

Development and Parametric Study of B/BaCrO4/FG Pyrotechnic Delay Composition

ABSTRACTStudies were undertaken to develop and experimentally investigate the effect of Boron content, Fish Glue (binder) and ambient temperature on the charge consumption and burning rate of Boron/Barium chromate/Fish Glue (B/BaCrO4/FG) pyrotechnic delay composition in short delay devices together with measurement of exothermicity of delay composition at different fuel/oxidizer ratios. The Boron content was varied from 5% to 45%, while Fish Glue content varied from 0% to 3.0%. The measured burning rate and charge consumption increased with increasing in Boron content until maximum values of burning rate and charge consumption were recorded at 18% boron. Similarly, both burning rate and charge consumption decreased with an increase in binder content and minimum values of these parameters were recorded at 3.0% Fish Glue. The calorific value of this delay mixture also increased with an increase in Boron content until maximum calorific value recorded at about 15% Boron. The composition failed to ignite by the calorimeter as well as by the igniter at Boron contents above 40%. The delay composition filled in delay tubes was then subjected to functional tests after conditioning at a temperature of +70°C, +21°C, and –40°C. The burning rate decreased with decreasing the ambient temperature.

Influence of boron content on the morphological, spectral, and electroanalytical characteristics of anodically oxidized boron-doped diamond electrodes

The effect of boron content in nanocrystalline anodically polarized boron doped diamond (BDD) thin films deposited at B/C ratio 500ppm – 8000ppm on their morphology, quality, and electrochemical and spectral properties was investigated using scanning electron and atomic force microscopies and Raman spectroscopy, where the shift of maximum Lorentzian component of diamond phonon at ∼1332cm−1 was used as the function of boron concentration. Cyclic voltammetry with the outer- and inner sphere redox markers ([Ru(NH3)6]3+/2+ and [Fe(CN)6]3−/4−) enables to differentiate among the semiconductive films (500ppm and 1000ppm) and films with metallic conductivity (2000ppm – 8000ppm). Nevertheless, only the inner sphere character of [Fe(CN)6]3−/4− redox marker enables to visualize the differences between individual boron content for metallic films. Further, reversible behavior with ΔEp of 59.8±0.9mV (n=5) and Ipa/Ipc ratio 1.00 at the scan rate of 100mVs−1 was achieved for this redox marker at 2000ppm film; this film just above the semiconductive/metallic threshold exhibited also favorable spectral (e.g., roughness surface factor) and electrochemical characteristics. The width of the potential window in aqueous media of different pH values and in wide variety of supporting electrolytes decreases with increasing boron content, with independence of anodic potential limit for 2000ppm – 8000ppm electrodes and more pronounced dependence of cathodic potential limit on boron content for all tested BDD films. Further, well-defined and highly reproducible anodic DP voltammetric peak of 2-aminobiphenyl with peak current increasing with boron content were obtained at ca +0.7V (vs. Ag/AgCl/3molL−1 KCl) at all BDD films tested.

Solvothermal synthesized boron doped TiO2 catalysts: Photocatalytic degradation of endocrine disrupting compounds and pharmaceuticals under visible light irradiation

Boron doped TiO2 (B-TiO2) photocatalysts with visible light activity were successfully synthesized by solvothermal method. The characterizations of the synthesized products were carried out by XRD, SEM-EDAX, BET, XPS, TGA-DTG and UV–vis spectroscopy. The band gap values of TiO2 were decreased with the increase of the boron doping level. XPS analysis revealed that the interstitial TiO2 structure was modified via formation of TiOB bonds. Photocatalytic degradations of endocrine disrupting compounds (2,4-dichlorophenol (DCP), bisphenol-A (BPA)) and non-steroidal anti-inflammatory drugs (ibuprofen (IBU), flurbiprofen (FLU)) were examined by using raw and boron doped TiO2 catalysts under UV-A and visible irradiation. Boron doping can remarkably enhance light utilization and improve the photocatalytic activity of TiO2 toward the selected organics. The effects of boron content, initial solution pH and H2O2 on the photocatalytic performance were studied. The BPA, DCP, IBU and FLU reaction rate constants of B-TiO2 (8wt.% B) were found as kBPA=5.989×10−2, kDCP=2.087×10−2, kIBU=1.818×10−2, and kFLU=1.319×10−2min−1. B-doped TiO2 catalysts were found to be effective for the consecutive degradation tests referring their potentiality in extended applications.

Effect of boron content on 1,4-butanediol production by hydrogenation of succinic acid over Re-Ru/BMC (boron-modified mesoporous carbon) catalysts

A series of Re-Ru bimetallic catalysts supported on mesoporous boron-modified carbon (denoted as Re-Ru/xBMC, x=B/C molar ratio) were prepared by a single-step surfactant-templating method and a subsequent incipient wetness impregnation method, and they were used for liquid-phase hydrogenation of succinic acid to 1,4-butandiol (BDO). The effect of boron addition on the catalytic activities and physicochemical properties of Re-Ru/xBMC catalysts was investigated. It was found that the addition of boron into carbon support affected surface area, metal dispersion, and reducibility of rhenium and ruthenium species in the Re-Ru/xBMC catalysts. It was also observed that boron species in carbon framework existed in several different phases such as substituted boron, partial oxidized boron, and boron oxide. In particular, the amount of substituted boron species was closely related to the hydrogen adsorption behavior of Re-Ru/xBMC catalysts. The amount of weak hydrogen-binding sites increased with increasing the amount of substituted boron species of the catalysts. Yield for BDO in the hydrogenation of succinic acid showed a volcano-shaped trend with respect to B/C molar ratio. This result was in good agreement with the amount of weak hydrogen-binding sites of the catalysts. It was revealed that TOFBDO increased with increasing the amount of weak hydrogen-binding sites of Re-Ru/xBMC catalysts. Among the catalysts, Re-Ru/0.04BMC with the largest amount of weak hydrogen-binding sites served as an efficient catalyst in the selective formation of BDO by hydrogenation of succinic acid.

The Effect of Boron Content, Crystal Structure, Crystal Size on the Hardness and the Corrosion Resistance of Electrodeposited Ni-B Coatings

The Effect of Boron Content, Crystal Structure, Crystal Size on the Hardness and the Corrosion Resistance of Electrodeposited Ni-B Coatings

Effect on Tensile Strength of Wood-based Carbon Fiber Impregnated by Boron

Wood-based carbon fiber derived from liquefied wood has the disadvantages of low mechanical strength and unstable performance. To improve its mechanical properties, wood-based carbon fiber precursors were impregnated with 5 wt.% and 8 wt.% boric acid solutions for 1 h and then carbonized at 900 °C for 1 h. The effect of boron content on fiber tensile strength and microstructure was investigated through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The tensile strength of wood-based carbon fibers impregnated with 5 wt.% boric acid reached 0.468 GPa, an increase of 44.89% compared with the untreated samples. In addition, the amount of graphitoidal crystal and the degree of graphitization increased with the boric impregnation. Furthermore, boron in the form of a boron-carbon solid solution in the graphene layer of carbon fibers effectively improved the tensile strength of wood-based carbon fibers.

Mechanical properties and tribological behavior of aluminum matrix composites reinforced with in-situ AlB2 particles

Aluminum matrix composites (AMCs) reinforced with in-situ AlB2 particles have been fabricated using a combination of powder metallurgy, hot rolling and solution treatment. The effects of boron content (7 and 12wt%), hot rolling and heat treatment parameters on the microstructures and mechanical properties of the composites were investigated by means of scanning electron microscopy (SEM), tensile test and micro-hardness measurements. The friction coefficient, wear behavior and scratch morphology of the AMCs and pure aluminum were also studied using scratch tests. The hardness and wear properties are higher in a case of composites when compared to unreinforced matrix material.

Effects of B<sub>2</sub>O<sub>3</sub> Contents on Crystallization Behaviors and Dielectric Properties of CaO-B<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> Glass Ceramics

The CaO-B2O3-SiO2 glass ceramics system with four different boron contents (14 wt. %, 16.4 wt. %, 18.6 wt. %, 21 wt. %) were prepared under 900oC. The properties and microstructures are characterized by Differential Scanning Calorimeter (DSC), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The effects of boron contents on the composition of crystalline phases and the properties of CaO-B2O3-SiO2 glass ceramics system were studied. The results show that when the molar ratio of CaO/SiO2 is 1.06, as the content of B2O3 increases, the major crystalline phases experiences the transformation from CaSiO3 to CaB2O4 and the content of α-SiO2 crystalline phase decreases, and the dielectric constant increases firstly but it decreases after the content of B2O3 reaches to 18.6 wt. %, while the dielectric loss tgδ of decreases gradually with the addition of boron content. When the content of B2O3 is 16.4 wt. %, the CaO-B2O3-SiO2 glass ceramics with a bulk density of 2.47 g/cm3 exhibits good dielectric properties (1 MHz): εr=6.03, tgδ=3.49×10-3.

Effect of boron content on the microstructure and magnetic properties of non-oriented electrical steels

The effects of boron content in the range of 0–0.0082 wt%, on the inclusion type, microstructure, texture and magnetic properties of non-oriented electrical steels have been studied. After final annealing, the addition of excess boron(w(Bt)〉0.004 1 wt%) led to the formation of Fe2B particles. As boron content increased, grain size increased and reached a maximum in steel with 0.004 1 wt% boron. Furthermore, steel containing 0.004 1 wt% boron had the strongest {100} fiber texture, Goss texture and the weakest {111} fiber texture among the five tested steels. Flux density firstly rapidly increased and then suddenly decreased with increasing boron content and reached a maximum in steel with 0.004 1 wt% boron. Conversely, core loss first sharply decreased and then abruptly increased with the increase of boron content and reached a minimum in steel containing 0.004 1 wt% boron. Steel containing 0.004 1 wt% boron obtained the best magnetic properties, predominantly through the development of optimum grain size and favorable texture.

Microstructure analysis of graphite/Cu joints brazed with (Cu-50TiH2) + B composite filler

Joining of carbon materials to copper will benefit the fabrication of plasma facing components for fusion applications. Graphite/Cu joints have been prepared by brazing with (Cu-50TiH2)+B composite filler in a vacuum. The effect of boron content in the composite filler on the mechanical property and microstructure of brazed graphite/Cu joints has been investigated. The average shear strength of joints increases with boron content raising from 0 to 15vol%. The maximum average shear strength of 19.8MPa was obtained with boron content of 15vol%. Then, the strength of joints decreases with boron content higher than 15vol%. The microstructure analysis of joints brazed with (Cu-50TiH2)+15vol% B filler indicates that TiB whiskers have been in situ synthesized in the filler layer. The filler layer is mainly composed of Cu based solid solution and Ti-Cu intermetallic compounds with TiB whiskers distributed inside. The distribution of TiB whiskers in the filler layer could serve as reinforcements, contributing to the improvement of graphite/Cu joints.

HIP法で固化成形した高耐食マトリックスを有するNi-Cr-Mo-B系耐食耐摩耗合金の諸特性に及ぼすB量の影響

HIP法で固化成形した高耐食マトリックスを有するNi-Cr-Mo-B系耐食耐摩耗合金の諸特性に及ぼすB量の影響

Effects of boron content on the glass-forming ability and mechanical properties of Co–B–Ta glassy alloys

The effects of boron content on the glass-forming ability, mechanical and elastic properties in Co92−xBxTa8 (at.%, x=30, 32.5, 35, and 37.5) bulk glassy alloys were investigated. Among these alloys studied, the Co59.5B32.5Ta8 alloy exhibits the highest glass-forming ability, which could form a glassy rod at least 3mm in diameter by the copper mold casting method. It is found that the plasticity of those glassy alloys increases with decreasing boron content. The plastic strains for the Co59.5B32.5Ta8 and Co62B30Ta8 BMGs are up to ∼2.1% and ∼2.5%, respectively. The decrease of shear modulus with decreasing boron content results in the increase of Poisson’s ratio, which is responsible for the improved plasticity. In addition, the strength of the ductile glassy alloys remains very high at above 5000MPa, although enhancing plasticity is accompanied by the loss of some strength. The present results show that Co–B–Ta bulk metallic glass with good glass-forming ability and significant plasticity as well as ultrahigh strength can be synthesized by adjusting alloy composition.

Preparation and Mechanical Characterization of Amorphous B-C Films

This study has demonstrated that trimethylboron, B(CH3)3 is a suitable boron source material for the fabrication amorphous boron carbide (a-BC:H) films. a-BC:H films were deposited by pluse plasma chemical vapor deposition on a silicon substrate (100) with different gas pressures and gas flow rates at constant voltage, -5 kV . The grown a-BC:H films were found to be porous surface and their thickness were in the range of 0.95 to 1.56 μm for 3 h of deposition time. Results indicated that the boron contents, morphologies and mechanical properties of the a-BC:H films were dependent on the gas pressures and gas flow rate. The increased of boron content will introduce more porous film surface. The effect of boron content on the mechanical properties such as hardness, Youngs modulus, and wear resistance were discussed. The good quality film is obtained from B(CH3)3 at 5 Pa and gas flow rate of 15 cm3/min which boron to carbon atomic ratio is 0.43. This film has lower friction coefficient (0.3) sliding against stainless steel ball, high hardness (8.1 GPa) and Youngs modulus (62.2 GPa).

Effect of boron content and welding current on the mechanical properties of electrical resistance spot welds in complex-phase steels

When complex phase steel where tensile strength is more than 1GPa grade is joined by resistance spot welding (RSW) optimum boron (B) content should be chosen to satisfy weldability and mechanical properties. Therefore, in this study, the effect of the B content (0–40ppm) on the tensile-shear strength of the RSW were investigated. As the resistivity of the base metal was independent on the B content it did not affect to nugget diameter. Regardless of the B content the specimens under 5t1/2 (t=sheet thickness) were fractured at interfacial failure mode. In the low welding current condition (lower than 6.4kA), measured nugget diameters were smaller than calculated critical nugget diameter regardless of the amount of B addition so that fracture mode was interfacial failure. Pull out failure occurred at the softened zone which was boundary between the base metal and the heat affected zone. Tensile-shear load of the specimen failure at the pull-out mode was increased as the fractured diameter and hardness of the softened zone were increased. Shear load was only dependent on the fractured diameter. The equations to calculate the shear and tensile-shear load were suggested for the specimens fractured at interfacial and pull-out failure modes respectively. Correlation coefficients between measured and calculated values of shear and tensile-shear load were 0.98 and 0.97, respectively. Therefore, shear and tensile-shear load of advanced high strength steel joined by RSW could be predicted successfully using the suggested equation.

Properties of graphitized boron-doped coal-based coke powders as anode for lithium-ion batteries

Coal-based coke powder is a by-product when coke is smashed for metallurgy and chemical industry. There is a vast output of coke powder every year around world, most of which is combusted as cheap fuel or abandoned directly. In this work, the electrochemical performance of graphitized boron-doped coal-based coke powder as anode for lithium ion batteries was investigated. The effects of boron content and graphitization temperature on the anode performance of boron-doped coal-based coke powder were also investigated in this paper. Results showed that a reversible capacity of 360.3mAh/g of boron-doped coal-based coke powder can be obtained, while that of unboron-doped was 292.9mAh/g. X-ray diffraction (XRD) analysis for the boron-doped coal-based coke powder showed that the distance between carbon layers was lowered by a proper amount of doped boron and higher graphitization temperature. X-ray photoelectron spectrometer (XPS) analysis was carried out to explain the effect of boron doping on the electrochemical performances of coal-based coke anodes.

高耐食マトリックスを有するNi - Cr - Mo - B 系ガスアトマイズ粉末の複硼化物生成挙動 に及ぼすB 量および熱処理の影響

高耐食マトリックスを有するNi - Cr - Mo - B 系ガスアトマイズ粉末の複硼化物生成挙動 に及ぼすB 量および熱処理の影響

Molecular dynamics investigation of Si–B–N ceramics: effects of boron content

Silicon boron nitride (SiBN) has the advantages of Si3N4 at high temperatures and also advantageous anti-oxidation and mechanical properties. While the synthesis methods of this new material are limited to the sol–gel route, understanding the structural and mechanical properties of SiBN becomes essential in order to control the properties under fabrication. In this study, atomistic models of SiBN ceramics with different boron content were built by melt-quench technologies. Pair distribution function and angular distribution function were applied to study the structural properties, and tensile loading was applied in order to obtain the stress–strain curves and mechanical properties of SiBN. Phase separation of SiN-rich region and BN-rich region was observed for SiBN with different B content. With B content increasing, the BN-rich region tended to be larger and the SiN-rich region became smaller. Si3B3N7 showed sharper and narrower peaks on distribution functions and larger Young's modulus than Si3BN5 and Si3B5N9.