Effect Of Boron Content Research Articles

Effect of boron content and quenching temperature on the microstructure and wear resistance of high boron steel

Abstract This article investigates the change rule of the microstructure, hardness and wear resistance of high boron steel containing 0.1 wt.% to 0.5 wt.% boron in the cast state and after quenching at different temperatures. The results show that the microstructure of cast high boron steel with different contents of boron is composed of pearlite, ferrite and eutectic boride, which has lower hardness and wear resistance, and the higher the content of boron, the higher the hardness and the better the wear resistance. After quenching at 900–1,000 °C, pearlite and ferrite change into a large number of lamellar martensite and a small amount of lath martensite. After high-temperature quenching at 1,050 °C, retained austenite appears in the microstructure in addition to martensite, and borides are partially dissolved. The hardness and wear resistance are significantly improved compared to the as-cast high boron steel. As the quenching temperature increases, the dissolution of boride is obvious, the hardness and wear resistance are firstly increased and then decreased. When the content of boron is 0.5 wt.% and the quenching temperature is 1,000 °C, the hardness reaches a maximum value of 59.0 HRC, and the abrasion resistance is the best.

Effect of Boron Content in LiOH Solutions on the Corrosion Behavior of Zr-Sn-Nb Alloy.

In pressurized water reactors, LiOH may be concentrated in some areas, leading to the accelerated corrosion of fuel claddings. Injecting boric acid into primary coolants can mitigate the accelerated corrosion effect of LiOH on Zircaloys, but the effects of boron content on the corrosion behavior of the Zr-Sn-Nb alloy are still unknown. This work focused on the corrosion and hydrogen absorption behavior at 360 °C/18.6 MPa in 100 mg/kg LiOH solutions with 0 mg/kg, 50 mg/kg, and 200 mg/kg boron contents for up to 510 days, aiming to study the effect of boron content on corrosion resistance in LiOH solutions. Corrosion kinetics, microstructures of oxide films, hydrogen absorption concentrations and hydride morphology were obtained after the test. The results show that injecting boron in LiOH solutions can significantly reduce the corrosion weight gain, hydrogen concentration, and hydrogen length of Zr-Sn-Nb alloys, that is, improving corrosion resistance effectively. During the oxidation of the Zr-Sn-Nb alloy, B3+ and Li+ incorporate in oxide films. The incorporation of Li+ may lead to the generation of oxygen vacancies, which can carry oxygen from the solutions to O/M interface, accelerating corrosion. The incorporation of B3+ in oxide films will slow down the oxidation of Zr-Sn-Nb alloys by reducing the oxygen vacancies caused by Li+ aggregation.

The Effect of Boron Content on the Microstructure and Magnetic Properties of Sintered Nd-Ce-Fe-B Magnets

The Effect of Boron Content on the Microstructure and Magnetic Properties of Sintered Nd-Ce-Fe-B Magnets

Effect of boron content on microstructure evolution and crystallization behavior of Fe7(CoNi)93-xBx (x=15, 18, 21) eutectic high-entropy alloys

The effect of boron content on microstructure evolution, glass-forming ability and crystallization behavior of Fe7(CoNi)93-xBx (x = 15, 18, 21) eutectic high-entropy alloys (EHEAs) was investigated. Bulk Fe7(CoNi)93-xBx EHEAs and ribbons were prepared by vacuum frequency induction melting furnace and melt-spinning method, respectively. The results show that the microstructure of as-cast hypoeutectic Fe7(CoNi)78B15 alloy consists of primary (Fe, Co, Ni) dendrite and lamellar eutectic. The eutectic Fe7(CoNi)75B18 alloy shows a fully lamellar eutectic structure consisting of (Fe, Co, Ni) phase and B-rich phase. The microstructure of hypereutectic Fe7(CoNi)72B21 alloy exhibits primary B-rich dendrite and lamellar eutectic. The as-spun Fe7(CoNi)75B18 and Fe7(CoNi)72B21 alloys show an amorphous structure. By comparison, the hypereutectic Fe7(CoNi)72B21 alloy shows an excellent glass-forming ability and thermal stability, which is attributed to the increase of crystallization activation energy induced by B addition. In addition, the increase of B addition inhibits the crystallization behavior, which is caused by the formation of stable covalent bonds between boron and other elements. This work provides an alternative route for the preparation of metallic glass by introducing the non-metallic boron component.

The Effect of Boron Content on the Structure and Mechanical Properties of Electron-Beam High-Entropy AlNiCoFeCrTiB Coatings

The Effect of Boron Content on the Structure and Mechanical Properties of Electron-Beam High-Entropy AlNiCoFeCrTiB Coatings

Effect of boron element on microstructure and mechanical properties of 316L stainless steel manufactured by selective laser melting

Boron(B)element is often utilized to enhance mechanical properties of stainless steel due to its excellent performance. In this study, selective laser melting (SLM) was used to print 316L/B stainless steel with varying boron weight content. The effects of boron content on microstructure, nanoindentation, and mechanical properties of the printed 316L stainless steel were discussed. Fine cell dendrites and columnar crystals were found in the SLM printed stainless steel due to the rapid solidification in SLM. It was found that boron has a higher growth limiting factor in the iron system and the boron solute can provide a high component supercooling. By adding boron element to stainless steel during printing, the honeycomb and grain size after solidification are significantly reduced due to interactions between the boron element and the 316L. Tensile testing results show that the ultimate tensile strength of the SLM fabricated parts with 0.5 wt% and 1 wt% boron element addition can be increased significantly to 1071 MPa and 1174 MPa, respectively.

Propane Oxidative Dehydrogenation on Nanosized Boron Carbide: Effect of Boron Content and Its Oxidation Implicated by DFT Calculations

Metal-free boron-containing materials are growing to be promising choices in oxidative dehydrogenation (ODH) of light alkanes to alkenes, while it remains unclear how the boron content and the second element that constitutes the scaffold to accommodate B in the materials may influence their catalytic activity. Herein, by means of the density functional theory study of nanosized boron carbide, we studied the mechanisms of ODH of propane (ODHP) catalyzed by three types of boron carbides, B13C2, B4C, and h-BC, which differ from each other in their B contents and their chemical topologies. The influence of hydroxyl coverage on the surface was also evaluated to address the structure–catalytic activity relationship in the ODHP reaction. The calculations show that (1) the B element content and the hydroxyl groups could regulate the electronic structure and significantly increase the highest occupied molecular orbital (HOMO) energy to promote chemical reactivity. (2) Boron carbide with higher coverage of hydroxyl groups on the surface (B13C2-H and B4C-H) exhibits higher activity for catalyzing ODHP reaction owing to the enhanced nucleophilicity, which is further confirmed by the noncovalent interaction (NCI) analysis. (3) The reactivity of the catalyst is positively correlated with the B content, and the ODHP catalyzed by B13C2 is kinetically more favorable than that by B4C and h-BC. This study is expected to enrich our understanding of the structure–activity relationship of boron-based catalysts in the ODH system and benefit the optimization of the catalytic systems.

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.

Polyborosilazanes with Controllable B/N Ratio for Si-B-C-N Ceramics.

Polyborosilazanes with controllable B/N ratio were synthesized using high-boron-content m-carborane, dichloromethylsilane, and hexamethydisilazane. After high-temperature pyrolysis, Si-B-C-N quaternary ceramics with SiC and B4C as the main phases were obtained. The B/N ratio in the precursors corresponded to the change in the feeding ratio of carborane and dichloromethylsilane. The effects of boron content and B/N ratio on the ceramic precursors and microphase structure in Si-B-C-N quaternary ceramics were explored in detail through a series of analytical characterization methods. A high boron content results in a significant increase in the ceramic yield (up to 71 wt%) of polyborosilazanes, and at the same time, the B/N molar ratio was regulated from 28.4:1 to 1.62:1. The appearance of the B4C structure in the Si-B-C-N quaternary ceramics through the regulation of the B/N ratio, has rarely been reported.

Effect of Boron Content on Microstructure and Impact Toughness in CGHAZ of Shipbuilding Steel Plates with Ca Deoxidation

Herein, the effect of boron (B) content on the microstructure and impact toughness in the coarse‐grained heat‐affected zone (CGHAZ) after large heat input welding of 400 kJ cm−1 for the EH40 shipbuilding steel plate with Ca deoxidation is studied. As the B content is increased from 0.0002 to 0.0024 wt%, the average width of grain boundary ferrites (GBFs) is decreased from 14.6 to 11.3 μm, the formation of acicular ferrite (AF) is promoted, and the formations of GBF and Widmanstatten ferrite (WF) are hindered in CGHAZ. The heat‐affected zone (HAZ) impact toughness is increased from 39 to 97 J at −20 °C. The fraction of low‐angle grain boundaries (LAGBs) is decreased from 40 to 29%, and the high‐angle grain boundaries (HAGBs) is increased from 60 to 71%. When the B content is 0.0024 wt%, the B atom segregates on the grain boundaries, and the widths of the segregation lines range from 2.3 to 3.6 μm. GBF is found to be the weakest zone in the CGHAZ. B addition can effectively reduce the formation of GBF, enhancing the critical crack stress and improving the HAZ toughness.

Effect of Boron Content on the Transverse Stress Rupture Properties of a Directionally Solidified Superalloy

The effect of boron content on the transverse stress rupture properties of a directionally solidified columnar superalloy is studied in present research. The experimental results indicate that the transverse stress property of the alloy containing 0.015% boron reaches the peak value at 870°C /380MPa while that of the alloy with 0.005% boron is the best at 1100°C/40MPa. At 870°C, dislocation slip is the main deformation mode. Stress concentration is induced when dislocations are hindered by precipitates at grain boundaries and interdendritic regions. And then cracks nucleate due to the stress concentration. In the alloy containing 0.015% boron, no borides precipitate and boron strengthens the grain boundary cohesion by solid solution. At 1100°C, grain boundary movement becomes the main deformation mode. In the alloy with 0.005% boron, the strengthening of grain boundary cohesion decreases comparing with that of alloy with 0.015% boron, and the resistance to grain boundary movement reduces with decreasing B content. Therefore, it results in compatible deformation between adjacent grains, resulting in the longest stress rupture lifetime.

Investigation on joining high borated stainless steels through electron beam welding technology

High borated stainless steels (HBSSs) are widely used in nuclear field because of excellent neutron-shielding ability. However, coarse network-like borides are prone to be formed in weld joints during welding process, deteriorating the ductility seriously. In this work, electron beam (EB) welding was adopted to join ∼3.5 mm thick HBSSs containing 0.30–2.12 wt. % boron. Benefiting from high energy density, fine γ-Fe matrix and network-like borides were obtained in fusion zone (FZ) and partially molten zone (PMZ) of weld joints. The effects of boron content, heat input and post weld heat treatment (PWHT) on the microstructure, mechanical properties and fracture behaviour of weld joints were investigated. As boron content increased, narrower PMZ was observed in weld joints owing to smaller solidification temperature range. The volume fraction and size of borides in PMZ/FZ raised, enhancing the strength and decreasing the ductility. Meanwhile, the fracture location of weld joints was closer to the interface of PMZ and base metal (BM) during deformation. Higher heat input brought a wider PMZ and larger penetration depth, but hardly changed the size and distribution of borides. Interestingly, it caused a steep slope of interfacial line between PMZ and BM, leading to the fracture along the interface with low ductility. After PWHT, the borides in PMZ/FZ were spheroidized, and the stress localization during deformation was weakened. Consequently, excellent weld joints exhibiting similar mechanical properties with base steels were produced. This systematic work provided a reference for welding other materials containing coarse and brittle secondary phases.

Effect of trace boron on grain refinement of commercially pure aluminum by Al–5Ti–1B

The effect of boron content on grain refinement of commercially pure aluminum by Al–5Ti–1B was quantitatively assessed. When the boron content is less than 0.03 wt.%, the refining performance of Al–5Ti–1B gradually is weakened as the boron content increases, which is attributed to the reaction of boron with the Al3Ti interlayer on TiB2 and the consumption of solute Ti. On the contrary, when the boron content exceeds 0.03 wt.%, the refining performance of Al–5Ti–1B gradually recovers with increasing boron content, which is related to the formation of primary AlB2 particles that provide additional nucleant substrates.

Effect of boron content on the microstructure and electromagnetic properties of SiBCN ceramics

Electromagnetic wave (EMW) absorbing materials have excellent potential for various applications in civil engineering and the military. In this study, siliconboron carbonitride (SiBCN) ceramics with excellent EMW absorption capability and oxidation resistance were obtained by adjusting the boron content. The results revealed that the graphite crystallite size in the SiBCN ceramics increased from 3.42 to 3.78 nm, whereas the thickness of the oxide layer decreased from 16.6 to 8.2 μm. The highest electrical conductivity and permittivity for the SiBCN ceramics were obtained when the boron content was 5%. The minimum reflection loss was −35.25 dB at 10.57 GHz and a ceramic thickness of 2.0 mm. At a temperature of 600 °C, the SiBCN ceramic exhibited excellent EMW attenuation ability; particularly, the minimum reflection loss reached −29.18 dB at 9.65 GHz and a ceramic thickness of 2.5 mm. The superior EMW absorption properties of the SiBCN ceramics at high temperatures can be ascribed to the synergistic effect of relaxation and conductivity. The results suggest that boron could enhance the transformation of amorphous carbon into crystalline graphite and increase the number of heterointerfaces and conductive paths. This work provides a method for obtaining SiBCN ceramics with excellent EMW absorption properties.

Boron‐containing nonwoven polymeric nanofiber mats as neutron shields in compact nuclear fusion reactors

Composite materials that contain thermally and chemically stable boron compounds are attractive candidates for applications that require high neutron absorption due to the large neutron absorption cross-section of boron. Electrospun polymer nanofibers have a unique volume-to-surface area, incorporating carbon and hydrogen atoms in their molecular structure that could moderate and thermalize incident neutrons. Nonwoven nanofibers could in turn reduce neutron scattering and increase neutron absorption by providing large surfaces and better atom economy in the shield materials. The expected high absorption will result from improved neutron interaction with high neutron absorbance hydrogen, carbon, and boron atoms in the nanofibers through increased specific surface area and atom economy. In this work, elemental boron-doped PVA polymeric nanofibers are produced for the first time to date for the application of neutron shielding. With the increasing demand for nuclear power generation and radiation therapies in medicine, the need for producing lightweight and flexible materials that could replace the traditional heavy metal/metal carbide-based shields is vital. Similarly, the need for flexible materials that could shield neutrons is also becoming critical for aerospace applications. The effect of boron content on the quality of fibers and neutron shielding capacity is evaluated by using an Am-Be neutron source. Characterization studies of produced nanofibers were carried out by SEM, TGA, FT-IR, and XPS analyses. Results have shown that PVA-based nanofibers doped with wt% 0.1 to 0.5 boron, having fiber diameter distribution between 60 and 330 nm range, could absorb up to 6% of neutron flux.

Effects of boron content on the microstructure and properties of B x C-TiB2 (x=4.5, 6.5 or 8.5) ceramic composites by the reactive spark plasma sintering

ABSTRACT B x C-TiB2 ceramic composites were fabricated via reactive spark plasma sintering using TiC and B as the raw materials. The impact of B/TiC mole ratios on the phase compositions, densification behaviors, microstructure, and mechanical properties of the ceramic composites were investigated. The results showed that the stoichiometry of ‘B x C’ could be tailored by changing initial boron content and the obtained B4.5C, B6.5C and B8.5C phases have the same crystal structure (R-3 m). The excess of B enhanced the reaction between TiC and B, which released a large amount of hot energy and promoted the densification of the composites. The TB8.5 composite sintered at 1900°C had the best comprehensive mechanical properties, with hardness and flexural strength of 40.36 GPa and 551 MPa, respectively. The formation of nano-sized TiB2 grains induced by reaction were beneficial for improving the mechanical properties of these composites.

Effects of Boron Content on the Toughness of Electro-Gas Welding-Deposited Metal

Effects of Boron Content on the Toughness of Electro-Gas Welding-Deposited Metal

Effect of Boron Content and Low-Temperature Annealing on the Structure State and Tribological Properties of Electrodeposited Ni-B Coatings

Effect of Boron Content and Low-Temperature Annealing on the Structure State and Tribological Properties of Electrodeposited Ni-B Coatings

Modelling the tribological response in dry sliding of boron modified as-cast Ti6Al4V on hardened steel

Tribological characteristics of boron modified as-cast Ti6Al4V alloys are not very well known, but these alloys enjoy improved as-cast mechanical properties and favourable manufacturing economy. Experimental results are reported here for the effects of sliding speed and normal load on the wear rate and the coefficient of friction in dry sliding of these alloys on hardened EN 31 steel. Alloys having 0%, 0.30%, and 0.55% boron by weight were tested. A full factorial experiment assessed the effects of boron content, speed, and load on wear and friction. Interactions between speed and load were found to be statistically significant in influencing the wear rate and the coefficient of friction. Regression models are developed to predict the wear rate and coefficient of friction responses. The developed contour plots can assist designers in choosing operating conditions when selecting these alloys even if the wear mechanisms are unknown. Evidence shows that the wear resistance of Ti6Al4V can be improved by boron addition, and wear regimes are sensitive to boron content.

Boron doped graphene synthesis using pulsed laser deposition and its electrochemical characterization

During the design of graphene (G), their electronic, chemical and electrochemical properties among others can be tuned by incorporating heteroatoms in the honeycomb structure. In this study, we investigated boron doped graphene (BG) synthesis and the effect of boron content on the electrochemical property of graphene. To this end, BG was synthesized using pulsed laser deposition (PLD) with carbon and boron as solid sources, followed by rapid thermal annealing in the presence of nickel catalyst. Raman spectroscopy revealed that the BG films consisted of few-layer graphene and boron doping increased the defects level in the films. X-ray photoelectron spectroscopy confirmed the successful boron doping into the graphene with the control of boron content. Electrochemical characterization demonstrated that BG electrodes exhibit higher reversibility and electron transfer constant than the G electrode. All these results prove that PLD method is a viable alternative way to produce BG films with excellent electrochemical properties.