Diffusional processes in the welding of some refractory carbides to metals

Borisova, A. L.; Evtushenko, O. V.

doi:10.1007/bf00797253

Cited by 7 publications

(3 citation statements)

References 6 publications

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“…As a consequence, the bulk diffusion constants of carbon in metal carbides are usually much lower than in the corresponding metals as visible in Figure 4. It is worth noting that the diffusional mobility of the metal atoms in carbides is still several orders lower than that of carbon atoms [103].…”

Section: Carbon Diffusion: Bulk Surface and Subsurfacementioning

confidence: 99%

Current understanding of the growth of carbon nanotubes in catalytic chemical vapour deposition

Jourdain

Bichara

2013

Carbon

503

334

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Due to its higher degree of control and its scalability, catalytic chemical vapour deposition is now the prevailing synthesis method of carbon nanotubes. Catalytic chemical vapour deposition implies the catalytic conversion of a gaseous precursor into a solid material at the surface of reactive particles or of a continuous catalyst film acting as a template for the growing material. Significant progress has been made in the field of nanotube synthesis by this method although nanotube samples still generally suffer from a lack of structural control. This illustrates the fact that numerous aspects of the growth mechanism remain ill-understood. The first part of this review is dedicated to a summary of the general background useful for beginners in the field. This background relates to the carbon precursors, the catalyst nanoparticles, their interaction with carbonaceous compounds and their environment. The second part provides an updated review of the influence of the synthesis parameters on the features of nanotube samples: diameters, chirality, metal/semiconductor ratio, length, defect density and catalyst yield. The third part is devoted to important and still open questions, such as the mechanism of nanotube nucleation and the chiral selectivity, and to the hypotheses currently proposed to answer them

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Section: Carbon Diffusion: Bulk Surface and Subsurfacementioning

confidence: 99%

Current understanding of the growth of carbon nanotubes in catalytic chemical vapour deposition

Jourdain

Bichara

2013

Carbon

503

334

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“…Before or during sintering this pore forming agent is removed thus leaving pores of predefined size. 4,5 Even though several variants of this method have been patented some time ago, applied investigations have been started only recently. [6][7][8][9] The development was mainly triggered by the need for new manufacturing technologies for highly porous medical implants.…”

Section: Introductionmentioning

confidence: 99%

Green strength of powder compacts provided for production of highly porous titanium parts

Laptev¹,

Vyal²,

Bram³

et al. 2005

Powder Metallurgy

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The production route of highly porous near net shape titanium parts includes the green machining of compacts made of metallic and pore former (often ammonium bicarbonate) powder mixtures. Success in green machining greatly depends on compact strength. The aim of the present work was to determine and quantitatively evaluate factors influencing the green strength of titanium-ammonium bicarbonate compacts. The substantial dependence of green strength on the amount of pore former and compaction pressure was demonstrated. Some influence of the particle size of ammonium bicarbonate on compact strength was also observed. A theoretical explanation of these experimental results is given. A sharp decrease of green strength owing to decomposition of ammonium bicarbonate in compacts during holding in air was experimentally found. The factors influencing decomposition, i.e. time, compaction pressure and particle size of pore former, were investigated in detail.

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“…The use of Fe catalysts implies the possible formation of Fe3C during reaction with the carbon precursor. Fe3C is temperature-dependent and may also catalyze the carbon nanotube formation, but it presents lower bulk carbon diffusion than Fe [37][38][39]. The diffusion coefficient of carbon trough α-Fe in the 600-725 ºC range is few orders of magnitude larger than that through Fe3C [40,41], and therefore the former will produce larger nanofilaments in the same period.…”

Section: Introductionmentioning

confidence: 99%

Cobalt doping of α-Fe/Al2O3 catalysts for the production of hydrogen and high-quality carbon nanotubes by thermal decomposition of methane

Torres

Pinilla

Suelves

2020

International Journal of Hydrogen Energy

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Diffusional processes in the welding of some refractory carbides to metals

Cited by 7 publications

References 6 publications

Current understanding of the growth of carbon nanotubes in catalytic chemical vapour deposition

Current understanding of the growth of carbon nanotubes in catalytic chemical vapour deposition

Green strength of powder compacts provided for production of highly porous titanium parts

Cobalt doping of α-Fe/Al2O3 catalysts for the production of hydrogen and high-quality carbon nanotubes by thermal decomposition of methane

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