scholarly journals INFLUENCE OF ALLOYING Ti, Mo AND W ON THE KINETIC AND STRENGTH CHARACTERISTICS OF MEMBRANE ALLOYS BASED ON Nb AND V

Author(s):  
Валерий Анатольевич Полухин ◽  
Римма Михайловна Белякова ◽  
Эльмира Джумшудовна Курбанова

Проведен анализ влияния Ti, Mo и W на характер аморфной нано- и кристаллической структуры на прочностные и кинетические характеристики - диффузии D и проницаемости Ф водорода в мембранных сплавах, созданных на основе бинарных Ni - Nb и V - Ni. Легирование сплавов Ni - V титаном, молибденом и вольфрамом ведет к постепенному замещению ими ниобия и ванадия и способствует образованию нескольких второстепенных фаз хотя и действующих как барьеры для диффузии водорода, но способствующих снижению процессов гидридообразования. Выявлена строгая зависимость кинетики водорода не только от термодинамических параметров -температуры и давления, но и от наличия свободного объема в формируемых аморфных, нано-кристаллических и кристаллических сплавов. Установлено, что процессы селективности, динамика водорода - его поток J, определяемый произведением диффузии и проницаемости (J = D×Ф), зависят от базового состава, выбора легирующих элементов (Ti,Mo и W ), а также формируемых структур - аморфной, нанокристаллической и полифазной дуплексной кристаллической микроструктурой. Установлено, что тщательно подобранный состав определяет производительность селективного процесса и способствует выделению высокочистого водорода с последующими его приложениями для зеленой энергетики. An analysis was carried out of influence of Ti, Mo and W on the nature of the amorphous nano- and crystalline structures on the strength and kinetic characteristics - diffusion D and permeability Ф of hydrogen in membrane alloys based on binary Nb - Ni, V - Ni. Doping with Nb - V alloys, titanium, molybdenum and tungsten leads to the gradual replacement of niobium and vanadium, and promotes the formation of several minor phases while acting as barriers for hydrogen diffusion, but contributing hydride reduction processes. A close dependence of the hydrogen kinetics was revealed not only on thermodynamic parameters - temperature and pressure, but also on the presence of free volume in the formed amorphous, nanocrystalline and crystalline alloys. So, the processes of selectivity, the dynamics of hydrogen - its flux J determined by the product of diffusion D and permeability Ф, J = D×Ф depend on the basic composition and the choice of alloying elements (Ti,Mo and W ), as well as the formed structures - amorphous, nanocrystalline and duplex, represented by multiphase crystalline microstructures. It was found that a carefully selected composition determines the productivity of the selective process and promotes the release of high-purity hydrogen with its subsequent applications for green energy.

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 589 ◽  
Author(s):  
Yugo Kato ◽  
Michio Suzuki

Metal nanoparticles (NPs), with sizes ranging from 1–100 nm, are of great scientific interest because their functions and features differ greatly from those of bulk metal. Chemical or physical methods are used to synthesize commercial quantities of NPs, and green, energy-efficient approaches generating byproducts of low toxicity are desirable to minimize the environmental impact of the industrial methods. Some microorganisms synthesize metal NPs for detoxification and metabolic reasons at room temperature and pressure in aqueous solution. Metal NPs have been prepared via green methods by incubating microorganisms or cell-free extracts of microorganisms with dissolved metal ions for hours or days. Metal NPs are analyzed using various techniques, such as ultraviolet-visible spectroscopy, electron microscopy, X-ray diffraction, electron diffraction, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Numerous publications have focused on microorganisms that synthesize various metal NPs. For example, Ag, Au, CdS, CdSe, Cu, CuO, Gd2O3, Fe3O4, PbS, Pd, Sb2O3, TiO2, and ZrO2 NPs have been reported. Herein, we review the synthesis of metal NPs by microorganisms. Although the molecular mechanisms of their synthesis have been investigated to some extent, experimental evidence for the mechanisms is limited. Understanding the mechanisms is crucial for industrial-scale development of microorganism-synthesized metal NPs.


MRS Bulletin ◽  
2006 ◽  
Vol 31 (10) ◽  
pp. 770-773 ◽  
Author(s):  
David S. Sholl ◽  
Y.H. Ma

AbstractDense metal membranes are a well-developed technology for the production of high-purity hydrogen. The physical mechanism of hydrogen transport across metal films—dissociation of molecular hydrogen, diffusion of interstitial atomic hydrogen, and subsequent recombinative desorption of molecular hydrogen—means that metal membranes can have extremely high selectivities for hydrogen transport relative to other gases. We describe current experimental and theoretical trends in the development of metal alloy membranes for hydrogen purification in practical, chemically robust processes.


Author(s):  
Ronald S. Weinstein ◽  
N. Scott McNutt

The Type I simple cold block device was described by Bullivant and Ames in 1966 and represented the product of the first successful effort to simplify the equipment required to do sophisticated freeze-cleave techniques. Bullivant, Weinstein and Someda described the Type II device which is a modification of the Type I device and was developed as a collaborative effort at the Massachusetts General Hospital and the University of Auckland, New Zealand. The modifications reduced specimen contamination and provided controlled specimen warming for heat-etching of fracture faces. We have now tested the Mass. General Hospital version of the Type II device (called the “Type II-MGH device”) on a wide variety of biological specimens and have established temperature and pressure curves for routine heat-etching with the device.


Author(s):  
G.D. Danilatos

Over recent years a new type of electron microscope - the environmental scanning electron microscope (ESEM) - has been developed for the examination of specimen surfaces in the presence of gases. A detailed series of reports on the system has appeared elsewhere. A review summary of the current state and potential of the system is presented here.The gas composition, temperature and pressure can be varied in the specimen chamber of the ESEM. With air, the pressure can be up to one atmosphere (about 1000 mbar). Environments with fully saturated water vapor only at room temperature (20-30 mbar) can be easily maintained whilst liquid water or other solutions, together with uncoated specimens, can be imaged routinely during various applications.


IEE Review ◽  
1990 ◽  
Vol 36 (1) ◽  
pp. 27
Author(s):  
David Lidgate
Keyword(s):  

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