Documents disponibles écrits par cet auteur

Effects of coolant chemistry on corrosion of 3003 aluminum alloy in automotive cooling system / Y. Liu in Materials and corrosion, Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 574–579 Titre : Effects of coolant chemistry on corrosion of 3003 aluminum alloy in automotive cooling system Type de document : texte imprimé Auteurs : Y. Liu, Auteur ; Y. F. Cheng, Auteur Année de publication : 2010 Article en page(s) : pp. 574–579 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : aluminum  alloys;  automotive  cooling  system;  cation  impurities;  corrosion;  ethylene  glycol Résumé : In this work, effects of coolant chemistry, including concentrations of chloride ions and ethylene glycol and addition of various ions, on corrosion of 3003 Al alloy were investigated by electrochemical impedance spectroscopy measurements and scanning electron microscopy characterization. In chloride-free, ethylene glycol–water solution, a layer of Al-alcohol film is proposed to form on the electrode surface. With the increase of ethylene glycol concentration, more Al-alcohol film is formed, resulting in the increase in film resistance and charge-transfer resistance. In the presence of Cl− ions, they would be involved in the film formation, decreasing the stability of the film. In 50% ethylene glycol–water solution, the threshold value of Cl− concentration for pitting initiation is within the range of 100 ppm to 0.01 M. When the ethylene glycol concentration increases to 70%, the threshold Cl− concentration for pitting is from 0.01 to 0.1 M. In 100% ethylene glycol, there is no pitting of 3003 Al alloy even at 0.1 M of Cl−. Even a trace amount of impurity cation could affect significantly the corrosion behavior of 3003 Al alloy in ethylene glycol–water solution. Addition of Zn2+ is capable of increasing the corrosion resistance of Al alloy electrode, while Cu2+ ions containing in the solution would enhance corrosion, especially pitting corrosion, of Al alloy. The effect of Mg2+ on Al alloy corrosion is only slight. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905323/abstract [article] Effects of coolant chemistry on corrosion of 3003 aluminum alloy in automotive cooling system [texte imprimé] / Y. Liu, Auteur ; Y. F. Cheng, Auteur . - 2010 . - pp. 574–579. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 574–579 Mots-clés : aluminum  alloys;  automotive  cooling  system;  cation  impurities;  corrosion;  ethylene  glycol Résumé : In this work, effects of coolant chemistry, including concentrations of chloride ions and ethylene glycol and addition of various ions, on corrosion of 3003 Al alloy were investigated by electrochemical impedance spectroscopy measurements and scanning electron microscopy characterization. In chloride-free, ethylene glycol–water solution, a layer of Al-alcohol film is proposed to form on the electrode surface. With the increase of ethylene glycol concentration, more Al-alcohol film is formed, resulting in the increase in film resistance and charge-transfer resistance. In the presence of Cl− ions, they would be involved in the film formation, decreasing the stability of the film. In 50% ethylene glycol–water solution, the threshold value of Cl− concentration for pitting initiation is within the range of 100 ppm to 0.01 M. When the ethylene glycol concentration increases to 70%, the threshold Cl− concentration for pitting is from 0.01 to 0.1 M. In 100% ethylene glycol, there is no pitting of 3003 Al alloy even at 0.1 M of Cl−. Even a trace amount of impurity cation could affect significantly the corrosion behavior of 3003 Al alloy in ethylene glycol–water solution. Addition of Zn2+ is capable of increasing the corrosion resistance of Al alloy electrode, while Cu2+ ions containing in the solution would enhance corrosion, especially pitting corrosion, of Al alloy. The effect of Mg2+ on Al alloy corrosion is only slight. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905323/abstract

Numerical simulation of droplet size distribution in vertical upward annular flow / Y. Liu in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 12 (Décembre 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 12 (Décembre 2010) . - 09 p. Titre : Numerical simulation of droplet size distribution in vertical upward annular flow Type de document : texte imprimé Auteurs : Y. Liu, Auteur ; W. Z. Li, Auteur Année de publication : 2011 Article en page(s) : 09 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : flow  (dynamics);  fluids;  turbulence;  computer  simulation;  bubbles;  computational  fluid  dynamics;  equations;  mechanisms Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The liquid droplet size distribution in gas-liquid vertical upward annular flow is investigated through a CFD (computational fluid dynamics)-PBM (population balance model) coupled model in this paper. Two-fluid Eulerian scheme is employed as the framework of this model and a population balance equation is used to obtain the dispersed liquid droplet diameter distribution, where three different coalescence and breakup kernels are investigated. The Sauter mean diameter d32 is used as a bridge between a two-fluid model and a PBM. The simulation results suggest that the original Luo–Luo kernel and the mixed kernel A (Luo’s coalescence kernel incorporated with Prince and Blanch’s breakup kernel) can only give reasonable predictions for large diameter droplets. Mixed kernel B (Saffman and Turner’s coalescence kernel incorporated with Lehr’s breakup kernel) can accurately capture the particle size distribution (PSD) of liquid droplets covering all droplet sizes, and is appropriate for the description of liquid droplet size distribution in gas-liquid annular flow. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27443 [...] [article] Numerical simulation of droplet size distribution in vertical upward annular flow [texte imprimé] / Y. Liu, Auteur ; W. Z. Li, Auteur . - 2011 . - 09 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 12 (Décembre 2010) . - 09 p. Mots-clés : flow  (dynamics);  fluids;  turbulence;  computer  simulation;  bubbles;  computational  fluid  dynamics;  equations;  mechanisms Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The liquid droplet size distribution in gas-liquid vertical upward annular flow is investigated through a CFD (computational fluid dynamics)-PBM (population balance model) coupled model in this paper. Two-fluid Eulerian scheme is employed as the framework of this model and a population balance equation is used to obtain the dispersed liquid droplet diameter distribution, where three different coalescence and breakup kernels are investigated. The Sauter mean diameter d32 is used as a bridge between a two-fluid model and a PBM. The simulation results suggest that the original Luo–Luo kernel and the mixed kernel A (Luo’s coalescence kernel incorporated with Prince and Blanch’s breakup kernel) can only give reasonable predictions for large diameter droplets. Mixed kernel B (Saffman and Turner’s coalescence kernel incorporated with Lehr’s breakup kernel) can accurately capture the particle size distribution (PSD) of liquid droplets covering all droplet sizes, and is appropriate for the description of liquid droplet size distribution in gas-liquid annular flow. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27443 [...]

Role of second phase particles in pitting corrosion of 3003 Al alloy in NaCl solution / Y. Liu in Materials and corrosion, Vol. 61 N° 3 (Mars 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 3 (Mars 2010) . - pp. 211–217 Titre : Role of second phase particles in pitting corrosion of 3003 Al alloy in NaCl solution Type de document : texte imprimé Auteurs : Y. Liu, Auteur ; Y. F. Cheng, Auteur Année de publication : 2010 Article en page(s) : pp. 211–217 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Aluminum  alloy;  pitting  corrosion;  second  phase  particles Résumé : The second phase particles in 3003 aluminum (Al) alloy were characterized by scanning electron microscope, energy-dispersive X-ray analysis and X-ray diffraction techniques. The role of second phase particles in Al alloy pitting corrosion was investigated by cyclic polarization measurement, and scanning vibrating electrode technique. Results demonstrated that the second phase particles in 3003 Al alloy are mainly Alx(Fe,Mn) intermetallics, with an average diameter of about 5 µm. The enrichment of Mn in second phase particles forms a galvanic cell effect relative to the adjacent Al alloy substrate. The initiation of pitting corrosion of 3003 Al alloy is the local dissolution of Al substrate around the second phase particles. When a sufficient amount of Al is dissolved away, the second phase particles drop off from the Al substrate, forming large pitting cavities that are usually linked each other. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905308/abstract [article] Role of second phase particles in pitting corrosion of 3003 Al alloy in NaCl solution [texte imprimé] / Y. Liu, Auteur ; Y. F. Cheng, Auteur . - 2010 . - pp. 211–217. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 3 (Mars 2010) . - pp. 211–217 Mots-clés : Aluminum  alloy;  pitting  corrosion;  second  phase  particles Résumé : The second phase particles in 3003 aluminum (Al) alloy were characterized by scanning electron microscope, energy-dispersive X-ray analysis and X-ray diffraction techniques. The role of second phase particles in Al alloy pitting corrosion was investigated by cyclic polarization measurement, and scanning vibrating electrode technique. Results demonstrated that the second phase particles in 3003 Al alloy are mainly Alx(Fe,Mn) intermetallics, with an average diameter of about 5 µm. The enrichment of Mn in second phase particles forms a galvanic cell effect relative to the adjacent Al alloy substrate. The initiation of pitting corrosion of 3003 Al alloy is the local dissolution of Al substrate around the second phase particles. When a sufficient amount of Al is dissolved away, the second phase particles drop off from the Al substrate, forming large pitting cavities that are usually linked each other. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905308/abstract