Boride Alloy Research Articles

Bifunctional metal–acid sites on nickel boride catalysts: Phenol hydrodeoxygenation and water-promoted C = C hydrogenation

Modification of earth-abundant metal catalysts with optimized catalytic performance can be potential alternatives to precious metal catalysts for more sustainable processes. Using a chemical reduction method, nickel boride (Ni3B) alloy catalysts were prepared with a Ni/B ratio of 3. Ex-situ and in-situ characterization indicates that the structure of Ni3B changes from amorphous to crystalline with increasing pretreatment temperatures. The presence of B does not seem to alter the electronic properties of Ni. However, after pretreatment, oxidized B species (i.e., BOx and H3BO3) ex-solve from the bulk, leading to the formation of a B-enriched surface. In-situ titration and dehydration reaction experiments demonstrate the presence of acid sites, which play an important promoting role in the hydrogenation of C = C bonds. Moreover, Ni3B catalysts show a remarkable activity towards phenolic ring hydrogenation with the added ability to deoxygenate the secondary products via dehydration on the acid sites. Under water-free reaction conditions, the Ni3B catalysts exhibit similar hydrogenation activity to that of a pure Ni catalyst. Remarkably, the addition of small amounts of water leads to a > 100-fold increase on Ni3B catalysts, while it inhibits the reaction on bare Ni catalyst by blocking active sites. These observations highlight the cooperative role of bifunctional sites in Ni3B catalysts and solvent composition for C = C hydrogenation reactions.

High-entropy borides with frame structure: Efficient electrocatalysts for oxygen evolution reaction

Innovative methods for producing catalytic nanomaterials are crucial for advancing environmental conversion and storage technologies. This study introduces a novel approach to fabricate a high-entropy boride alloy with a frame structure, FeCoNiMgB/NF, using in situ growth of high-entropy alloy powder on nickel foam (NF). The resulting frame-structured FeCoNiMgB/NF high-entropy boride alloy exhibits superior electrocatalytic performance for the oxygen evolution reaction (OER) compared to pure FeCoNiMgB powder and other counterparts. It demonstrates a low overpotential of 183 mV at a current density of 10 mA cm−2, a Tafel slope of 34 mV dec−1 in 1 M KOH, and excellent stability over 72 h without significant decay.The outstanding catalytic performance of the frame-structured FeCoNiMgB/NF high-entropy alloy can be attributed to the synergistic effects of FeCoNiMgB–NF, a larger specific surface area, and excellent frame-structure conductivity. The alloy's long-term stability is a result of the gradual formation of the FeCoNiMgOOH lath structure array during the reaction process, facilitating low adsorption and charge transfer energies as per theoretical calculations. This study presents a new method for constructing advanced frame-structured high-entropy boride alloys, promising advancements in energy conversion and storage technologies.

Amorphous Cobalt Boride Alloy Synthesized by Liquid Phase Methods as Electrode Materials for Electrochemical Capacitors

AbstractAn amorphous cobalt boride alloy with high electronic conductivity is fabricated through the liquid‐phase reduction method. Benefiting from large specific surface area and hierarchical pore structure, the as‐synthesized Co‐B nanoflakes expose substantial electrochemical active sites, promote the transfer of electrons and ions, and accelerate the redox kinetic process. The as‐obtained amorphous Co‐B alloy sample displays a specific capacitance of 411 F g−1 at 0.5 A g−1, and with the current density increased to 10 A g−1, it maintains 69% of the initial capacitance. The as‐assembled asymmetric supercapacitor device reveals electrochemical properties comprising an excellent specific capacitance of 64.3 F g−1 at 0.25 A g−1, superior cyclical stability of 105% after 20,000 cycles at 3 A g−1, and maximum energy density of 22.9 Wh kg−1 at a power density of 200.3 W kg−1. This study demonstrates great potential in developing high‐conductivity materials for an asymmetric supercapacitor through utilizing an amorphous cobalt boride alloy as a promising electrode material.

Microstructure and magnetic properties of nanocrystalline cobalt–zirconium boride alloy prepared by melt spinning and subsequent annealing

The structural, thermal and magnetic characteristics of cobalt–zirconium boride (Co80Zr18B2) alloy were investigated in this work. In this regards, cobalt–zirconium boride samples with different structures and crystallite sizes were prepared using a copper boat vacuum induction melting plus melt-spinning and subsequent annealing processes. Prepared samples were characterized using X-ray diffraction, field emission scanning electron microscopy, differential scanning calorimetry and vibrating sample magnetometer. According to X-ray diffraction results, cobalt–-zirconium (Zr2Co11) single phase can successfully form by means of a melt-spinning process at a wheel speed of 40 m s−1. The saturation magnetization and coercivity of this sample are 58 emu/g and 3 kOe, respectively, which exhibit a hard magnetic property. Cobalt–zirconium compound which formed during melt-spinning process was not stable and transformed to Co23Zr6 during annealing process up to 500 °C. The maximum value of coercivity (Hc = 3.4 kOe vs. 3 kOe for single Zr2Co11 phase) is related to cobalt–zirconium boride alloy after annealing at 500 °C for 1 h.

Tuning the magnetic and structural properties of a three-metal boride alloy: Mn0.95−δFe1.05+δ−xCoxB

We present a comprehensive study of the three-metal boride alloys Mn0.95−δFe1.05 + δ−xCoxB (δ=0−0.15 and x=0−1.05) synthesized via arc melting and annealing. The alloys crystallize in a body-centered tetragonal unit cell in the same space group (I4/mcm) as the parent compound Mn2B. A small amount of MB (M = Mn, Fe, Co) impurity forms in the as-cast samples which is removed by acid treatment. Rietveld refinement on the powder X-ray data reveals an anisotropic variation of lattice parameters in the series. The c-axis increases with increasing Co content but the a-axis decreases. Magnetic measurements show a non-monotonic variation of both Tc and the saturated magnetization Ms as a function of x. These findings highlight the tunable nature of Mn0.95−δFe1.05 + δ−xCoxB and motivate further studies of metal-rich boride alloys.

Characterization and corrosion resistance of boride layers on carbon steel

Boriding treatment was carried out at 850, 900, 950, 1000 and 1050 °C for 2, 4 and 8 h on carbon steel. The effect of some treatment parameters such as the chemical composition of the mixture, boriding temperature and time were investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM) and microhardness tests were used to describe the formed boride layers. Some properties of boride layers have been studied such as corrosion and wear resistance. The obtained results confirm that the corrosion resistance of boride carbon steel was improved compared to no-boriding steel. The dry abrasive wear resistance of boride alloy samples is about 5 times greater than that of non-boride ones.

Controlled synthesis of uniform multilayer hexagonal boron nitride films on Fe2B alloy.

Two-dimensional (2D) hexagonal boron nitride (h-BN) is highly appreciated for its excellent insulating performance and absence of dangling bonds, which could be employed to maintain the intrinsic properties of 2D materials. However, controllable synthesis of large scale multilayer h-BN is still very challenging. Here, we demonstrate chemical vapor deposition (CVD) growth of multilayer h-BN by using iron boride (Fe2B) alloy and nitrogen (N2) as precursors. Different from the self-limited growth mechanism of monolayer h-BN on catalytic metal surfaces, with sufficient B source in the bulk, Fe2B alloy promotes the controllable isothermal segregation of multilayer h-BN by reacting with active N atoms on the surface of the substrate. Microscopic and spectroscopic characterizations prove the high uniformity and crystalline quality of h-BN with a highly orientated layered lattice structure. The achievement of large scale multilayer h-BN in this work would facilitate its applications in 2D electronics and optoelectronics in the future.

Nanostructured Amorphous Nickel Boride for High‐Efficiency Electrocatalytic Hydrogen Evolution over a Broad pH Range

AbstractA fruitful paradigm in the development of low‐cost and efficient water splitting systems for hydrogen generation is to search the highly active non‐noble catalysts towards hydrogen evolution reaction (HER). Here, the electrocatalytic HER activity of nanostructured amorphous nickel boride (Ni−B) alloy has been investigated. Amorphous Ni−B has exhibited excellent catalytic efficiency and long‐term stability for HER over a broad pH range, which is actually comparable to the performance of Pt. This high catalytic activity is due to the amorphous structure and the moderate electron structure of Ni−B. The Ni−B catalyst is easily obtained via electroless plating technique and we could get a supported Ni−B catalyst on desired substrates. Given the low cost, abundance, corrosion resistance, high efficiency and ease of fabrication, amorphous Ni−B is among the best alternatives to noble metal hydrogen evolution catalysts for water splitting.

A simple method for correcting the neutron self-shielding effect of matrix and improving the analytical response in prompt gamma-ray neutron activation analysis

A simple method using an internal standard is proposed to correct for the self-shielding effect of B, Cd and Gd in a matrix. This would increase the linear dynamic range of PGNAA in analyzing samples containing these elements. The method is validated by analyzing synthetic samples containing large amounts of B, Cd, Hg and Gd, the elements having high neutron absorption cross-section, in aqueous solutions and solid forms. A simple Monte-Carlo simulation to find the extent of self-shielding in the matrix is presented. The method is applied to the analysis of titanium boride alloy containing large amount of boron. The satisfactory results obtained showed the efficacy of the method of correcting for the self-shielding effects in the sample.

Exceptional electrochemical activities of amorphous Fe–B and Co–B alloy powders used as high capacity anode materials

Ultrafine amorphous alloy powders (UAAP) of Fe–B and Co–B were synthesized and tested for possible use as electroactive anodic materials. It is found that unlike their parent elements, the transition metal (TM) and boron, the Fe–B and Co–B alloy powders show superior electrochemical activities when used as anodic materials in aqueous alkaline solution. The discharge capacities of Fe–B and Co–B electrodes were observed to be 1200 and 1100 mAh/g at moderately high rate of 100 mAh/g, respectively, much higher than the theoretical capacity of currently used zinc metal (820 mAh/g). The exceptional high capacities of the boride alloys were found due to the electrochemical activation of boron atoms in the highly dispersed transition metal atoms. Inversely, the activated boron clamps the electrode potential to a negative region to prevent the transition metal from passivating.

Selective hydrogenation of 2-ethylanthraquinone over an environmentally benign NiB/SBA-15 catalyst prepared by a novel reductant–impregnation method

An environmentally benign SBA-15-supported amorphous nickel boride alloy catalyst, prepared by a novel reductant–impregnation method, exhibits superior activity, selectivity, and stability in the selective hydrogenation of 2-ethylanthraquinone (eAQ) to 2-ethylanthrahydroquinone (H 2eAQ), which is the dominating process for the production of hydrogen peroxide in industrial scale. The unique characters of the amorphous alloy as well as the pore structure of the mesoporous SBA-15 molecular sieve are crucial for the excellent catalytic behavior of the title catalyst.

Preparation and characterization of MCM-41 and silica supported nickel boride catalysts

Ni-B/MCM-41 and Ni-B/SiO 2 catalysts were prepared by low-temperature reduction of surface-adsorbed nickel chloride with ethanolic sodium borohydride solution. XRD analysis showed that the MCM-41 framework of Ni-B/MCM-41 catalyst remained intact, while nitrogen adsorption–desorption study revealed uniform pore size distribution of the channel system. Thermal treatment of this catalyst under nitrogen at 450°C indicated the presence of a segregated nickel phase on the surface of MCM-41. On amorphous silica, however, amorphous nickel boride alloy may have formed. As-synthesized Ni-B/MCM-41 is more susceptible to oxidation than Ni-B/SiO 2 probably due to the smaller size of its alloy particles. This suggestion is also supported by the EXAFS results. The lower activity of Ni-B/MCM-41 catalyst than Ni-B/SiO 2 in benzene hydrogenation reaction probably reflects the lower reducibility of nickel oxide phase than nickel boride alloy phase.

The Microstructure and Superplastic Behavior of Clean Mechanically Alloyed Titanium–Titanium Boride Alloys

AbstractThe superplastic forming (SPF) of titanium alloys is an established technology. A reduction in grain size from that of the typical sheet materials would lead to enhanced SPF properties and hence a reduction in production cycle times. This study describes the microstructural development and superplastic behaviour of fine-grained Ti-6%Al-4%V alloys. Ball-milling Ti-6%Al-4%V powder produces a nanocrystalline material; however on consolidation by hot isostatic pressing rapid grain growth occurs. Addition of boron powder during milling leads to boride precipitates in the matrix of the consolidated alloy. The precipitates are dispersed inhomogeneously, resulting in localized grain refinement. Superplastic testing revealed cavitation formation but in comparison to conventional sheet material, large elongations were achieved at relatively high strain rates.

A Low Temperature Route for the Synthesis of Rare Earth Transition Metal Borides and Their Hydrides

Synthesis of rare earth-based alloys by the ORD technique consists in the reduction of rare earth oxides in a melt of calcium under argon, and simultaneous diffusion–reaction of the just formed rare earth metal with the other elements. This method has been applied with success to numerous ternary borides containing transition metals such as the magnetic alloys Y2Co14B, LnCo4B, and YCo3B2. By using a small excess of Ca, boride particles grow in a viscous slurry media containing unreacted (melted) Ca and nanosize CaO particles. Single phase boride alloys can be obtained at 1000°C as loose micrometer-size particles of very high crystal quality as confirmed by the sharp diffraction peaks on the corresponding X-ray diagrams. Particles can be easily recovered by gentle washing in diluted weak acid solution, and dried under vacuum at room temperature. This rather low temperature technique is particularly adapted to the synthesis of incongruent melting phases, as well as for the alloys containing volatile rare earth elements (Sm, Yb, Tb,…).

ほう化合金粉末とＮｉ粉末を添加したＭｏ圧粉体の焼結挙動

We studied the sintering behavior of No powder compacts with an addition of boride alloy powders and Ni powders. These boride alloys are CrB, TiB2 and WB which have high decomposition temperature. The results of this experiment are as follows:1)Though relative densities of sintered No powder compacts with an addition of boride alloy powders slightly rise up, these boride alloy powders do not disintegrate at sintering temperature.2)The liquid phase produces in matrices of No powder compacts with supplementary addition of Ni powder at sintering temperature and promotes the densification.3)Two endothermic peaks in DTA curve denote points of liquid phases. We infer that the endothermic peak at low temperature side is the transient liquid phase, because the liquid phase produces temporarily at parts of the matrix in heating up to melting point. The other endothermic peak corresponds to the melting point of No powder compact.4)WB alloy powder in No powder compacts with an supplementary addition of Ni powder decomposes at lower temperature than that of WB boride compound.

Fatigue strength of low carbon steel with hard boride alloy bonded on.

In order to improve the erosion resistance of heat exchanger tubes in fluidized-bed boilers, small blocks of Boride alloys were diffusion bonded on the low carbon steel tubes. It was anticipated that these blocks could reduce the fatigue strength because of the stress concentration at the corner of bonded blocks and the difference of hardness between the tube and the blocks.Fatigue tests were performed on plate and tube specimens made of boiler graded low carbon steels with and without bonded Boride blocks and the fatigue crack initiation behavior was studied experimentally. Low carbon steel tubes with the Boride alloy blocks were found to have the equivalent fatigue strength to the low carbon steel without Boride blocks. Analyzing the test results, it was concluded that the crack initiation behavior of tube specimens was controlled by two counteracting effects, namely beneficial effects o f compressive residual stress and boron diffusion, and detrimental effect of corner notch.It was concluded that low carbon steel tubes with boride alloys can be employed in the fluidized-bed boilers much the same way as usual tubes without boride blocks.

The properties including some crystallochemical properties of mixed borides of group IVa-Va elements

The conditions of preparation for refractory borides and their solid solutions by the method of self-propagating high temperature synthesis were studied. It was established that borides synthesized in a vacuum possess a higher purity than those obtained in an argon atmosphere. The use of a higher magnesium boride (88 wt.% B-12 wt.% Mg) as a boronizing agent reduced the rate of the burning process and extended the region of homogeneous solid solutions of boride obtained during the synthesis. Some physicochemical properties (such as microhardness, density and crystal lattice parameters) of boride alloys were determined and their dependence on the alloy composition was established.

Reinforced iron boride materials

1. An iron boride alloy introduced by infiltration into the pores between molybdenum wires and an iron matrix ensures strong bonding between the wires and the matrix. 2. During the manufacture of a RIBM diffusion zone transition layers form around the molybdenum wires. The transition layers consist of variable-composition solid solutions comprising all the elements present in the composite. 3. Reinforcement with molybdenum wires substantially increases the thermomechanical fatigue resistance of an IBM. 4. It is shown that Co and Ni can be successfully used as bases of low-melting-point infiltrating materials (LiMs) in the manufacture of RIBMs.

Gas-impermeable protective thermocouple sheaths from zirconium boride

A study was made with the object of producing gas-impermeable sheaths from zirconium boride with 5% Mo additions and of testing such sheaths under industrial conditions. It is shown that the liquid phase which forms during sintering as a result of the reaction of molybdenum with zirconium boride gives rise to substantial shrinkage and helps to obtain gas-impermeable parts. Zirconium boride alloys with up to 10% Mo consist of a single phase.