Rapid or explosive heating of electrically conductive films has several applications, and the use of reactive laminates to increase output energy is an intriguing concept. Past studies have shown electrically heated aluminum/nickel (Al/Ni) nano-laminate films to augment this energy by an amount approximately equivalent to the expected heat of mixing between the two elements, which for most intermetallics is a significant fraction of the total heat of reaction (86% for Al/Ni). In this study, we investigate the use of sputtered aluminum/boron (Al/B) laminates to determine whether a similar increase, as measured by the velocity of an ejected flyer layer, occurs. However, observed velocities in any samples containing boron were 38% to 45% lower than samples without boron, despite much higher heats of reaction reported in the literature for Al/B. We attributed this reduction to the vaporization temperature of boron being much higher than that of Al, and because Al electrical resistivity at elevated temperatures was still much lower than boron, boron heating was less efficient as vaporized Al expanded and drove the ejected flyer. These results and analysis give insight into other reactive material combinations in which one of the constituents is an electrical insulator.

The chemical-vapor deposition conditions for the growth of pure boron (PureB) layers on silicon at temperatures as low as 400°C were investigated with the purpose of optimizing photodiodes fabricated with PureB anodes for minimal B-layer thickness, low dark current and chemical robustness. The B-deposition is performed in a commercially-available Si epitaxial reactor from a diborane precursor. In-situ methods commonly used to improve the cleanliness of the Si surface before deposition are tested for a deposition temperature of 450°C and PureB layer thickness of 3 nm. Specifically, high-temperature baking in hydrogen, and exposure to HCl are tested. Both material analysis and electrical diode characterization indicate that these extra cleaning steps degrade the properties of the PureB layer and the fabricated diodes.

Low density (LD) steels have shown particular characteristics in terms of mechanical properties and microstructure, since they have high strength, high ductility and density reduction up to 18%. On the other hand, the addition of microalloying elements such as Ti and B generate hardening by solid solution and precipitation, as well as grain refinement effect. LD steels generate nano-sized kappa phase precipitated from the austenite matrix, and these advanced steels can reach strength and elongation up to 780 MPa and 60%, respectively. The main objective of this research work is the metallographic, structural and mechanical characterization of a LD steel microalloyed with Ti/B in as-cast and -homogenized conditions. For this purpose a Fe-27Mn-7Al-1.2C (%wt) LD steel microalloyed with Ti/B was melted in a vacuum-induction furnace and cast in metallic mold. LD-Ti/B steel samples were homogenized at 1100 °C during 20, 50, 100, 150 and 200 minutes followed by water quenching. Metallographic, structural and mechanical characterization was carried out by optical (LOM) and scanning electron (SEM) microscopy, X-ray diffraction (XRD) and microhardness Vickers testing (HV10), respectively. In general, results showed a typical dendritic microstructure with average grain size of 1256 μm in the as-cast condition. On the other hand, the as-homogenized condition showed an austenitic equiaxial microstructure with average grain size from 164 to 940 μm. Austenite, ferrite and kappa phases were detected by X-ray diffraction (XRD). Also, second-phase particles such as AlN, TiC and MnS were detected by LOM and SEM-EDS analysis. LD steel microalloyed with Ti/B exhibited the highest microhardness Vickers value (235 HV10) in the as-cast condition, whilst in the as-homogenized condition microhardness gradually decreases from 223 to 198 HV10 as holding time increases.

Crystallized FeB and Fe2B powders were synthesized by a molten salt method with elemental Fe and B powders as starting materials. The results indicated that the presence of molten NaCl/KCl salts and the excess of Fe or B powders were essential to obtain pure FeB or Fe2B powders. The formation mechanism of iron borides was investigated by examining the phase compositions of the obtained products with different molar ratio of Fe/B. It was found that Fe powders firstly reacted with B powders to form Fe2B phase, and FeB phase formed from the reaction between Fe2B and excessive B. The as-synthesized FeB and Fe2B powders had a uniform short-rod and plate like morphology, respectively. Both FeB and Fe2B exhibited typical soft magnetic behavior. The saturation magnetization and the coercivity were 36.4 emu/g and 15.5 kA/m for FeB, 126.9 emu/g and 6.1 kA/m for Fe2B, respectively. The electrochemical performances of the as-synthesized FeB powders were evaluated by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance test.

Borate is present in natural groundwaters and borate is also released into groundwaters when borosilicate glass, waste form for high level nuclear waste, is corroded. Borate can form an aqueous complex, AmHB4O72+, with actinides in +III oxidation state. In this work, we present our evaluation of the equilibrium constant for formation of AmHB4O72+ and the associated Pitzer interaction parameters at 25°C.

Using Nd(III) as an analog to Am(III), solubility data of Nd(OH)3(s) in NaCl solutions in the presence of borate ion from the literature, is used to determine Am(III) interactions with borate. The log10K for the formation reaction is 37.34. This evaluation is in accordance with the Waste Isolation Pilot Plant (WIPP) thermodynamic model in which the borate species include B(OH)3(aq), B(OH)4–, B3O3(OH)4–, B4O5(OH)42–, and NaB(OH)4(aq). The WIPP thermodynamic database uses the Pitzer model to calculate activity coefficients of aqueous species.

In addition, the equilibrium constant for dissolution of AmB9O13(OH)4(cr) at 25oC is evaluated from the solubility data on NdB9O13(OH)4(cr) in NaCl solutions, again using Nd(III) as an analog to Am(III). The log10K for the dissolution reaction is –79.30. In the evaluation for log10K for the dissolution reaction, AmHB4O72+ is also considered.

The equilibrium constant and Pitzer parameters evaluated by this study will be important to describe the chemical behavior of Am(III) in the presence of borate in geological repositories.

The focus of this paper is on analysis, comparison and research on the colorful low-temperature, lead-containing overglazes on glazed porcelain body and on the enamel glazes on the metal body of the Qing Dynasty by adopting several analytical methods. Analysis and tests on the element, boron in overglaze on glazed porcelain body and enamel glaze on metal body, were performed using laser induced breakdown spectroscopy (LIBS), and the results showed that Cloisonné enamel, painted enamel and Falangcai samples contained boron, while Famille Rose (Fencai) samples did not contain boron. Meanwhile, such analysis methods as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), energy dispersive X-ray spectroscopy (EDXRF), Micro-Raman, stereomicroscope and Confocal laser scanning microscopy (CLSM) were used to test and observe the element composition, crystal composition and microstructure of the samples. The results illustrated that matrix glaze of Cloisonné enamel, painted enamel and Falangcai was the same. The yellow glaze was a lead-alkali glass and other color glazes were boron-lead-alkali glass, while all color glazes of Famille Rose were lead-alkali glass. Colorful low-temperature overglaze on glazed porcelain body and enamel glaze on metal body had a common practice and technology in the use of opacifiers and colorants. Compared to painted enamel, the painting technique of Famille Rose was more complicated, and effect was apparently praised as being superior.

Recently, a new boron allotrope B52 with orthorhombic structure was theoretically predicted to be more stable than α-tetragonal boron B50. In experiments however, only tetragonal boron phases have been obtained so far. Here, we report for the first time on the preparation of orthorhombic boron phase of B52-type, space group Pnnn, a = 8.894 Å, b = 8.784 Å, c = 5.019 Å, by normal-pressure annealing of α-tetragonal boron, synthesized at high pressures by pyrolysis of decaborane, B10H14. We have investigated temperature-induced structure evolution and thermal desorption of boron samples, which allowed us to regard the structure of mother “α-tetragonal boron” as a boron-rich hydride with composition close to B51.5H7.7. In accordance with density-functional theory calculations, the most preferable sites of hydrogen placement in tetragonal unit cell are 8j and 4g; the tetragonal-to-orthorhombic transition takes place spontaneously upon complete dehydrogenation.

High-Mn Twinning-Induced Plasticity (TWIP) steels are advanced high-strength steels (AHSS) currently under development; they are fully austenitic and characterized by twinning as the predominant strengthening mechanism. TWIP steels have high strength and formability with an elongation up to 80%, which allows reduction in automotive components weight and fuel consumption. Since the targeted application field of TWIP steels is the automotive industry, steels need high mechanical performance with good weldability and excellent corrosion resistance. However, there is lack of information about the weldability behavior of these advanced steels. This research work aims to study the weldability of a new generation of high-Mn austenitic TWIP steels microalloyed with B. Weldability was examined using spot welds produced by Gas Tungsten Arc Welding. Microstructural changes were examined using light optical metallography. Segregation of elements in the weld joint was evaluated using point and elemental mapping chemical analysis by Scanning Electron Microscopy and Electron-Dispersive Spectroscopy; while the hardness properties were examined with Vickers microhardness testing (HV25). Experimental results show that the welded joint microstructure consists of austenitic dendritic grains in the fusion zone, and equiaxed grains in the heat affected zone. Notably, the boron microalloyed TWIP steel exhibited poor weldability, showing hot cracking. Additionally, the studied TWIP steels showed a high degree of segregation in the fusion zone; Mn and Si segregated into the interdendritic regions, while Al and C preferentially segregated in dendritic areas. Finally, the welded joints of the TWIP steels showed microhardness values lower than the base material. In general, the present TWIP steels have problems of weldability, which are corroborated with microstructural changes, elements segregation and microhardness loss.

Boron nitride nanotubes (BNNTs), an analogue of carbon nanotube (CNT) is one of the most used non-metallic materials in high technology applications related to thin film fabrications. Taking advantage of their unique properties such as electrically non-conductive, thermally conductive, and high hardness, it has been used in high-temperature electronic devices, multifunctional aerospace materials, and structures and electric and aerospace systems. The main goal of this project was to use BNNTs in the fabrication of nano epoxycomposites to enhance their thermal and mechanical properties to use it for applications in aerospace constituents. In order to accomplish this goal, BNNTs were functionalized with isopherone diisocyante (IPDC). Surface analysis techniques were employed to ensure the modification BNNTs and study the interface of the reinforced composites before and after the modification. Mechanical and thermal conductivity testing was performed in order to understand the quality of the composites. Three different nanocomposites were accomplished with hBN and BNNTs using two different epoxy polymers and three curing agents. The systems EPON 862/Curing Agent W/ (hBN or BNNTs) have Tgs and tan deltas higher compared with those fabricated at the same conditions without nanoparticles. The fabricated BN composites showed improved physical properties due to their particle dispersion and boron nitrite intermolecular interactions with the epoxy polymer.

In the present work, the stress relaxation method was employed to determine the influence of B addition on the kinetics of strain-induced precipitation and its interaction with the static austenite recrystallization. For this purpose, the behavior of two low carbon advanced ultra-high strength steels was analyzed during stress relaxation tests at different temperatures and constant pre-strain rate. The precipitation start (Ps) and finish (Pf) times were determined from the relaxation curves and then the corresponding precipitation-time-temperature diagrams were constructed for each steel. Transmission Electron Microscopy was used to determine the chemical nature and evolution of precipitation. In general, the results show that the addition of B retards the austenite recrystallization, tends to accelerate the precipitation kinetics of carbonitrides and leads to a finer and denser distribution of precipitates. These results are discussed in terms of the driving force for the nucleation of precipitation, which in turn is controlled by the degree of supersaturation of microalloying element and as a function of B segregation and B-vacancy complexes to dislocations and grain boundaries.

We have demonstrated the synthesis of highly reactive boron nanomaterials by alkali metal reduction of BCl3 under sonication, followed by annealing. Unlike ordinary boron powders, these materials combust completely and release close to their theoretical energy content (based on elemental analysis) in polymer protected bomb calorimetry experiments. We have scaled up the synthesis using a commercial (Columbia International CIT-UHiPR-U1000V600) ultrasonic hi-pressure reactor. The synthesis reactions exhibit a scale problem, where they yield diminishes considerably on scale up, probably a result of alkali metals becoming trapped inside a mass of salts and rendered unable to react. We measured the combustion properties of the materials by bomb calorimetry, and thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), and report elemental analyses on selected samples.

Nano-sized metallic powders have advantages as fuels including faster, more complete combustion than micron-sized metal powder particles; however, the unpassivated nanoparticles of some metals of interest, such as Al, are pyrophoric and highly reactive, making them difficult to handle. Additionally, metal-hydrides are of great potential interest for a significant gravimetric energy increase without a penalty in the volumetric energy content, as the inclusion of hydrogen in the metallic matrix does not significantly decrease overall density of the material. Reactive metal amorphous powders produced by the sonochemical decomposition and dehydrogenation of an in situ-produced mixed borohydride-tetrahydroaluminate of titanium and containing hydrogen are examined in the current work and show exceptional air-stability and higher energy content than nano-Al. An aerosolized powder burner is used to investigate the combustion behavior of these powders mixed with gaseous fuels to quantify the energy density and reaction rate as compared to commercial aluminum powders in an effort to benchmark the performance of the sonochemically generated amorphous Ti-Al-B powder fuels.

Advanced ultra-high strength steels (A-UHSS) are revolutionizing both the steel and automotive industries, therefore it is imperative to study their hot plastic deformation behavior and modeling. The flow characteristics of all hot forming processes consist basically of two competitive phenomena: strain hardening and softening due to dynamic mechanisms (recovery and/or recrystallization). In this research work, the softening parameter was determined in a low carbon A-UHSS microalloyed steel with different amounts of boron (0, 14 and 214 ppm). Experimental stress–strain data of uniaxial hot-compression tests at different temperatures (950, 1000, 1050 and 1100 °C) and strain rates (10–3, 10–2 and 10–1 s–1) were used. The stress–strain relationships as a function of temperature and strain rate were described on the basis of the Estrin, Mecking, and Bergström model. The experimental values of the softening parameter Ω were adjusted using the least-squares method. In general, the results reveal that the softening parameter increases with increasing boron content.

The development of safe, efficient, and economic hydrogen storage technologies is key for implementation of a hydrogen-based energy economy. In the search for high-hydrogen content materials, attention in the past decade has shifted to amides and borohydrides, two representative solid-state chemical sorption materials with high hydrogen capacities that had not been previously explored for hydrogen storage. A large number of new amide and borohydride systems have recently been developed that expand the material scope for hydrogen storage. This article reviews the current progress in amides and borohydrides with emphases on material design and kinetic improvement.

Single phase erbium borides ErB2, ErB4, and ErB12 show Seebeck coefficients and power factors with absolute values that are significantly lower than those of a stable Er-B multi phase composite obtained through high temperature solid-solid reaction from the elements (molar ratio Er:B = 1:6). According to quantitative Rietveld analysis the composite consists of erbium diboride (1 %), tetraboride (83 %), and dodecaboride (16 %), and the measurement of the electrical conductivities, Seebeck coefficients, and thermal conductivities leads to ZT values as high as 0.53 at 830 K. Such refractory materials can be used for energy conversion in a range of high temperatures that are otherwise difficult to address.