Metallurgical and mechanical examinations of molybdenum/graphite joints by vacuum arc pressure brazing using Ti-Zr filler materials

Dong, Longlong; Chen, Wenge; Hou, Lintao; Wang, Jiaojiao; Song, Jiulong

doi:10.1016/j.jmatprotec.2017.06.007

Cited by 21 publications

(10 citation statements)

References 13 publications

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“…Однако до сих пор её практическое применение было затруднено из-за сложного процесса расчета координационных чисел (Z) и отсутствия молярных объемов в жидком состоянии ( ) некоторых компонентов (например, С, Ta, V 2 O 5 , Cu 2 S, CaSiO 3 ). Упрощение MIVM достигнуто путем придания обоим Z i и Z j значений, равных 10, и заменой молярного объема i-компонента в жидком состоянии на его молярный объем в твердом состоянии (V i ) [13][14][15][16].…”

Section: теоретический анализunclassified

PHASE EQUILIBRIA IN THE Hg–Se SYSTEM DURING VACUUM DISTILLATION

Korolev¹,

Shunin²,

Тимофеев³

et al. 2022

MET

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Abstract. One of the possible ways to recover components from the Hg–Se alloy formed during the processing of copper-electrolyte sludge is vacuum distillation. Object of research: Hg–Se alloys of composition, mol %: 0.01–99.99 Hg; 99.99–0.01 Se, the formation of which is possible during the processing of copper-electrolyte sludge in the production of commercial selenium concentrate. The purpose of the work: calculation of the “gas – liquid” VLE (vapor liquid equilibrium) equilibrium states, including the dependence of the phase composition on temperature (T – x) and pressure (P – x) for the Hg–Se alloy during vacuum distillation. Methods and approaches used. The activity coefficients of the Hg–Se alloy components were calculated using a simplified version of the simple molecular interaction volume model (SMIVM). Phase diagrams of temperature (T – x) and pressure (P – x) are used to pre-select the system temperature and pressure, and to evaluate the efficiency of component separation during vacuum distillation. Novelty: calculation of activity coefficients using a simplified version of the SMIVM model. Main results. In the temperature range of 823‒1073 K, saturated vapor pressures were calculated for Hg (pHg * = 1.418·106‒1.046·107 Pa) and Se (pSe * = 1.42·104‒3,66·105 Pa). High values of the ratio pHg */pSe * = 100.2‒28.6 and the separation coefficient lgβHg = 2.73‒1.01 create theoretical prerequisites for the selective separation of these metals by vacuum distillation, when mercury is enriched in the gas phase (βHg > 1), and selenium – in the liquid phase. The molar fraction of selenium in the gas phase xSe = 0.553–1.43·10‒12 decreases with a decrease in the temperature of 1073‒823 K and the molar fraction of the element in the alloy xSe = 0.99–0.01. For the “liquid – gas” interface of the Hg–Se alloy, the values of changes in the excess Gibbs energy, enthalpy, and entropy are determined ‒ΔGm E = 0.8–3.0 kJ/mol; ‒ΔHm E = 1.86–5.39 KJ/mol; ‒ΔSm E = 0.99–2.94 J/mol.K. Practical significance: reducing the number of time-consuming and expensive installation experiments during the processing of Hg–Se compositions to optimize the temperature and pressure values of the vacuum treatment process distillation in order to obtain Se-containing products of a given composition.

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Section: теоретический анализunclassified

PHASE EQUILIBRIA IN THE Hg–Se SYSTEM DURING VACUUM DISTILLATION

Korolev¹,

Shunin²,

Тимофеев³

et al. 2022

MET

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“…The main preparation processes, related techniques, and concerned points of WK are shown in Fig. 5 [27,67,68].…”

Section: Preparation Of Wkmentioning

confidence: 99%

“…The accompanied stress concentration makes a significant reduction in toughness. Tungsten-potassium or potassium-doped tungsten (WK), which brings in nano-sized K bubbles to pin GBs and dislocations, and simultaneously enhances the toughness and strength, is of great importance in PFMs [12,13,16,[27][28][29][30][31][32][33][34][35]. The main mechanical properties and preparation of WK are reviewed in this paper.…”

Section: Introductionmentioning

confidence: 99%

Tungsten–potassium: a promising plasma-facing material

2019

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Tungsten-potassium (potassium-doped tungsten or WK), initially known from the electric filament industry, is a promising plasma-facing material (PFM) in future fusion facilities like International Thermonuclear Experimental Reactor (ITER). However, the brittle nature of W and irradiation-induced defects of WK materials may result in a risk of deuterium-tritium reaction failure in fusion reactors. Previous studies revealed that advanced W with ultrafine grains and nanostructures might be able to address these problems. However, K-doped W, a rapidly developed material for PFMs, lacks a systematical summary. In this review, we firstly describe the powder metallurgy and plastic deformation for the preparation of WK. Then, the mechanical properties of WK and thermal shock resistance results are reviewed. Important issues such as irradiation damages from neutron, heavy ion, and plasma (H isotope or He) irradiation are also discussed. Hitherto, WK under irradiations shows comparable or even better performances compared with other counterparts such as ITER grade pure tungsten. This review could be benefitial to the future efforts of improving the ductility and irradiation tolerance of WK materials.

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“…In view of the problems in the previous study on graphite/Mo joining including high pressure (0.1 MPa for diffusion bonding [2] and 0.5-1.0 MPa for vacuum arc pressure brazing [1]), high joining temperature (1650°C for diffusion bonding [2] and 1350-1680°C for brazing with Ti-containing fillers [3,4]), and the toxicity of Be in the Ti-Zr-Nb-Be filler, it is meaningful to join graphite to Mo with non-toxic filler at relatively low joining temperature and pressure.…”

Section: Introductionmentioning

confidence: 99%

Joining of graphite to Mo using Ti/Cu and Ti/Cu/Nb/Ti/Cu foils

Xu,

Huang,

Jiang

et al. 2023

Science and Technology of Welding and Joining

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Graphite/Mo joining has been carried out using Ti/Cu or Ti/Cu/Nb/Ti/Cu foils. The joining region in the joint using Ti/Cu foils is mainly composed of Ti 3 Cu 4 and TiCu. The joining region using Ti/Cu/Nb/Ti/Cu foils contains a joining zone I, an Nb interlayer and a joining zone II. Both the joining zones I and II are made up of Ti 3 Cu 4 and TiCu. The Nb foil diffuses and dissolves into the liquid fillers during the bonding. The joint using Ti/Cu/Nb/Ti/Cu foils shows higher shear strength than that using Ti/Cu foils, implying the contribution of Nb foil to the joint stress relief and to the joint strength promotion.

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Metallurgical and mechanical examinations of molybdenum/graphite joints by vacuum arc pressure brazing using Ti-Zr filler materials

Cited by 21 publications

References 13 publications

PHASE EQUILIBRIA IN THE Hg–Se SYSTEM DURING VACUUM DISTILLATION

PHASE EQUILIBRIA IN THE Hg–Se SYSTEM DURING VACUUM DISTILLATION

Tungsten–potassium: a promising plasma-facing material

Joining of graphite to Mo using Ti/Cu and Ti/Cu/Nb/Ti/Cu foils

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