Study on Interfacial Tension and Flammability of Mg-Ca-Ce Alloy Melt

2011 ◽  
Vol 418-420 ◽  
pp. 383-386 ◽  
Author(s):  
Xian Kuo Meng ◽  
Wei Min Zhao ◽  
Jian Ding
Keyword(s):  
Interfacial Tension ◽  
Composite Film ◽  
Flame Retardant ◽  
Ignition Temperature ◽  
Active Element ◽  
Mg Alloy ◽  
Ignition Point ◽  
Surface Active Element ◽  
Surface Active

The Mg-Ca-Ce ignition-proof Mg-alloy with high ignition temperature was developed based on the synergy of flame retardant role of Ca element and Re element ,and the flame retardant mechanism were investigated. The interfacial tension of Mg-Ca-Ce alloy melt was measured with the maximum bubble method. The interfacial tension is found to be remarkably lowered with the increase of Ce element that is a kind of surface active element to Mg-Ca alloy. The results also showed that the compact composite film composed of Ce2O3,CaO and MgO could be formed and reduce the flammability significantly when the Ca content and Re content were 1.2wt.% and 1.5 wt.% respectively, which prevented alloys from oxidation further and raised the ignition point nearly 150°C.

scholarly journals Interfacial phenomena between molten iron and molten slag–Effect of nitrogen on the Marangoni convection

2021 ◽  
Vol 56 (13) ◽  
pp. 7811-7822
Author(s):  
Taishi Matsushita ◽  
Ilja Belov ◽  
Dimitrios Siafakas ◽  
Anders E. W. Jarfors ◽  
Masahito Watanabe
Keyword(s):  
Marangoni Convection ◽  
Sessile Drop ◽  
Active Element ◽  
Slag System ◽  
Molten Iron ◽  
Interfacial Phenomena ◽  
Surface Active Element ◽  
Gas System ◽  
Surface Active ◽  
Calculated Velocity

Abstract In order to investigate the influence of the surface-active element on the interfacial phenomena between molten iron and molten Al2O3-CaO-SiO2 slag, a mildly surface-active element, nitrogen, was introduced, and the interfacial phenomena were directly observed using an X-ray sessile drop method. The multiphysics model was employed to calculate the velocity of the Marangoni convection caused by the surface/interfacial tension gradient along with the contour of the sessile drop. Movement of the sessile drop was observed in the experiment, and the driving force of the movement was discussed from the distribution of surface tension active element viewpoint. The calculated velocity of the Marangoni convection in the droplet was reasonably agreed with the literature data for the metal-gas system, and thus, the same model was applied for the metal-slag system. The velocity of the Marangoni convection for the metal-slag system becomes ten times lower compared to that of metal-gas system. Graphical abstract

Fundamental Research on the Mechanism of High-Speed Welding Undercut

2011 ◽  
Vol 287-290 ◽  
pp. 2152-2155 ◽  
Author(s):  
Peng Fei Huang ◽  
Chao Tang ◽  
Zhen Yang Lu
Keyword(s):  
Temperature Gradient ◽  
High Speed ◽  
Active Element ◽  
Flow Direction ◽  
Surface Flow ◽  
The Other ◽  
Welding Pool ◽  
Surface Active Element ◽  
Fundamental Research ◽  
Surface Active

Undercut is one of the most important problems which restrict welding speed. The research indicated that surface flow direction of welding pool near the periphery is the most important reason of undercut occurred. When the existence of surface active element (e.g. the content of S is about 0.02-0.04% in steel) change the sign of surface tension temperature coefficient to positive, undercut always occurs in TIG moveless welding, and not occurs when the content of S in iron is very low( e.g. S% is less 0.01%). Temperature gradient is the most important factor which influences the depth of undercut. The depth of undercut is bigger with the increase of temperature gradient when the other parameters are the same. When filling metal into welding pool, it restrained the molten metal movement from periphery to the pool center. So it can reduce the tendency of undercut, and eliminate undercut as increasing of filling metal ultimately.

Effect of Ce Addition on the Ignition-Proof Properties and Surface Tension of AZ91D-2.5Ca(Wt.%) Magnesium Alloy

2014 ◽  
Vol 788 ◽  
pp. 82-87 ◽  
Author(s):  
Lin Qin ◽  
Jian Ding ◽  
Zheng Fang ◽  
Wei Min Zhao
Keyword(s):  
Surface Tension ◽  
Magnesium Alloy ◽  
Oxide Film ◽  
Magnesium Alloys ◽  
Ignition Temperature ◽  
Active Element ◽  
Alloying Element ◽  
Surface Oxide Film ◽  
Ignition Point ◽  
Ce Content

In order to develop ignition-proof magnesium alloys, the effect of alloying element Ce on the ignition-proof properties and surface tension of AZ91D-2.5Ca alloy were investigated. The results show that the addition of Ce can significantly raise the ignition temperature and change the structure of surface oxide film as well as the surface tension. When the Ce content increases to 1.2%, the ignition point reaches 1371K. Upon the addition of Ce, the oxide film of AZ91D-2.5Ca melt changes to fine and close structure from the porous structure before the Ce addition. The composite oxide film mainly composed of MgO, Al2O3, CaO and Ce2O3. The surface tension of AZ91D-2.5Ca decrease with the increasing Ce content, as the active-element Ce enriched at the melt surface.

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