Showing papers on "Nickel boride published in 2014"

Selection of peptides binding to metallic borides by screening M13 phage display libraries.

Abstract: Background: Metal borides are a class of inorganic solids that is much less known and investigated than for example metal oxides or intermetallics. At the same time it is a highly versatile and interesting class of compounds in terms of physical and chemical properties, like semiconductivity, ferromagnetism, or catalytic activity. This makes these substances attractive for the generation of new materials. Very little is known about the interaction between organic materials and borides. To generate nanostructured and composite materials which consist of metal borides and organic modifiers it is necessary to develop new synthetic strategies. Phage peptide display libraries are commonly used to select peptides that bind specifically to metals, metal oxides, and semiconductors. Further, these binding peptides can serve as templates to control the nucleation and growth of inorganic nanoparticles. Additionally, the combination of two different binding motifs into a single bifunctional phage could be useful for the generation of new composite materials. Results: In this study, we have identified a unique set of sequences that bind to amorphous and crystalline nickel boride (Ni3B) nanoparticles, from a random peptide library using the phage display technique. Using this technique, strong binders were identified that are selective for nickel boride. Sequence analysis of the peptides revealed that the sequences exhibit similar, yet subtle different patterns of amino acid usage. Although a predominant binding motif was not observed, certain charged amino acids emerged as essential in specific binding to both substrates. The 7-mer peptide sequence LGFREKE, isolated on amorphous Ni3B emerged as the best binder for both substrates. Fluorescence microscopy and atomic force microscopy confirmed the specific binding affinity of LGFREKE expressing phage to amorphous and crystalline Ni3 Bn anoparticles. Conclusions: This study is, to our knowledge, the first to identify peptides that bind specifically to amorphous and to crystalline Ni3B nanoparticles. We think that the identified strong binding sequences described here could potentially serve for the utilisation of M13 phage as a viable alternative to other methods to create tailor-made boride composite materials or new catalytic surfaces by a biologically driven nano-assembly synthesis and structuring.

Laser production of B–Ni complex layers

Abstract: The paper presents the results of modification with nickel and laser treatment of boronized layers produced on C45 steel. The objective of the study was to investigate the microstructure and selected properties of the new layer. The boronized layer modified with nickel was produced by the galvanic-diffusion method. Galvanic coating was produced first; next the galvanic-coated sample was diffusion boronized at 950 °C for 4 h. This resulted in a two-zone microstructure consisting of a continuous subsurface zone and underlying needle-like iron borides. In the continuous zone microhardness was in the range of 1100–1200 HV0.1 while in the second zone of the needle-like microstructure the microhardness was between 1600 HV0.1 and 1400 HV0.1. Galvanic-diffusion boronickelized layers were modified by using CO2 laser technology. As a result of the laser beam impact the presence of three zones was observed: remelted (MZ), heat affected (HAZ) and the substrate. Laser heat treatment was carried out by two methods. The first method consisted of remelting the galvanic-diffusion layer. The second method consisted of alloying galvanic coating with boron. Microhardness measurements of the surface layers were made before and after laser modification. An advantageous effect of laser modification on the microhardness of boronickelized layers was found. Microhardness profiles of boronickelized layers after laser modification were characterized by a smooth transition from the remelted zone through the heat affected zone to the substrate. In the remelted zone the microhardness was approximately 1100 HV0.1. In this study, also an X-ray phase analysis was carried out. Nickel boride phases Ni3B and Ni4B3 were detected in the nickel modified boronized layer. In addition, the nonequilibrium phase of iron boride Fe3B occurred in the laser-modified layers. Laser modification had a positive effect on the wear resistance of nickel modified boronized layers.

Synthesis of Ni2B nanoparticles by RF thermal plasma for fuel cell catalyst

Abstract: The catalyst of Ni2B nanoparticles was successfully prepared using nickel and boron as precursors with the quenching gas in radio frequency thermal plasmas. The generating of Ni2B needs adequate reaction temperature and boron content in precursors. The quenching gas is beneficial for the synthesis of Ni2B in RF thermal plasma. The effect of quenching rate, powder feed rate and boron content in feeding powders on the synthesis of nickel boride nanoparticles was studied in this research. The high mass fraction of 28 % of Ni2B nanoparticles can be generated at the fixed initial composition of Ni:B = 2:3. Quenching gas is necessary in the synthesis of Ni2B nanoaprticles. In addition, the mass fraction of Ni2B increases with the increase of quenching gas flow rate and powder feed rate.

C5/C6 alkane isomerization catalyst loaded with nickel boride as well as preparation method and application method thereof

Abstract: The invention relates to a C5/C6 alkane isomerization catalyst loaded with nickel boride as well as a preparation method and an application method thereof. The catalyst comprises a carrier and the nickel boride the weight of which is 1-5% of that of the carrier, wherein the carrier is formed by aluminium oxide and an H beta molecular sieve; the weight ratio of the aluminium oxide to the H beta molecular sieve is (1:9)-(9:1). According to the catalyst provided by the invention, halogen components are not needed to be added, and noble metals are not used, so that the environmental pollution is avoided and the catalyst cost is reduced; besides, the catalyst can be directly used for isomerization process without requiring pre-hydrogenation for reduction. Tests prove that when the catalyst is used for isomerization reaction for catalyzing n-hexane and n-pentane, the activity of the catalyst is higher, and the isoalkane selectivity and the catalyst stability are better.

Synthesis of Raspberry and Ginger Ketones by Nickel Boride-catalyzed Hydrogenation of 4-Arylbut-3-en-2-ones

Abstract: Raspberry and ginger ketones 1 [1] and 2 [2] are well-known natural substances which became the objects of both laboratory and industrial synthesis. Owing to their intensive fragrance they found applications in perfumery, cosmetics and as food additives [3, 4]. Investigations of the biological activity of the phenolic compounds 1 and 2, in particular antioxidant [5 – 7] and anti-inflammatory [6 – 8] actions, cancer prevention [8, 9] and influence on the metabolic rate [10, 11] are still ongoing. In addition to that, the preparation of these simple structures with unusual properties is interesting as an educational process [12]. One of the general approaches to the synthesis of ketones 1 and 2 includes an aldol condensation of 4-hydroxybenzaldehyde and 4-hydroxy3-methoxybenzaldehyde (vanillin) with acetone followed by the reduction of the double bonds of the corresponding intermediate α ,β -unsaturated ketones 3 and 4 (Schemes 1 and 2). The first step is simple and cheap to realize, however for the reduction of enones 3 and 4 rather expensive hydrogenation catalysts (palladium [1, 13], platinum [2], rhodium [12], or Raney nickel [14]) have been used. Transition metal catalysis except rhodium is also complicated by a partial reduction of the carbonyl function [12]. Some other specific methods and reagents such as sodium amalgam [15], sodium hydrotelluride [16], baker’s yeast [17, 18], and aluminum halide-induced ionic hydrogenation [19] were employed for the 1,4-reduction of compounds 3 or 4. At last, highly efficient hydrogenation was achieved with neodymium oxide/polyethylene glycolsupported nickel boride [20]. In the present paper we report an easier and cheaper procedure for the transformation of enones 3 and 4 into raspberry and ginger ketones in good yield using nickel boride as hydrogenation catalyst.

Hydrodechlorination of Et3NBCl3 Catalyzed by Amorphous Nickel Boride – A Mechanistic Approach

Abstract: The catalytic hydrodechlorination of BCl3 with molecular hydrogen in the presence of tertiary amines is a viable strategy for the energy-efficient generation of valuable B–H bonds. A mechanistic study based on experiments with isolated intermediates and deuterium labeling experiments is presented. The occurrence of the rate-limiting reverse reaction from the insoluble Et3NHCl adduct was identified as a major cause of low Et3NBH3 yields. In addition, amines with NCH2 units, which also serve in the corresponding cases as solvents, have a strong influence on the reaction kinetics; they are directly involved in the hydrogen transfer at elevated temperatures and assume the role of a cocatalyst. A catalytic cycle for the reaction on a nickel boride catalyst is proposed.

Studies on electroless nickel boride coating on boron carbide particles

Abstract: Ni–B alloy deposits were successfully formed over alkali surface treated boron carbide by electroless technique and the effects of processing parameters such as reduction bath pH, temperature and post-heat treatment were investigated. Microstructural studies show remarkable changes in structural morphology from mesh-like structure to platelet type Ni–B coating. The main Ni–B phases observed were NiB, Ni2B, Ni3B and Ni4B3. An effective Ni–B alloy coating with better surface characteristics was formed at pH 8 under 75°C reaction bath temperature in the presence of bath stabiliser. The post-heat treatment of Ni–B coated particles under varying bath reaction temperatures at 400°C showed remarkable Ni–B phase transformation from metastable NiB and Ni2B to stable crystalline Ni3B phase. The NiB coated particle shows lower particle–matrix interfacial reaction, better wettability and enhanced dispersion in aluminium composites compared to uncoated particles.

Application of nickel-boride coating on metal surfaces

Abstract: FIELD: process engineering.SUBSTANCE: invention relates to surface metallisation processes, particularly, to application of nickel-boride coating on metal surface by autocatalytic deposition from alkaline solution. Proposed solution contains the following components, in wt %: nickel chloride - 0.35-0.63, sodium borohydride - 0.025-0.105, lead tungstate- 0.0018-0.0054, ethylenediamine - 20.0-28.0, sodium hydroxide to pH of 10.0 to 14.0, demineralised water making the rest. Prior to coat deposition current at density of 0.027±0.005 A/cmis fed to processed part. In particular cases, current is fed for 5-60 seconds while solution concentration and temperature are selected to allows deposition rate of 10-12 mcm/h.EFFECT: higher mechanical strength and adhesion, sufficient resistance to abrasion.3 cl