The Experts below are selected from a list of 21090 Experts worldwide ranked by ideXlab platform
Mehdi Fattahi - One of the best experts on this subject based on the ideXlab platform.
-
reduction of weld metal diffusible hydrogen content by adding colloidal nanosilica to the Electrode Coating
International Journal of Hydrogen Energy, 2016Co-Authors: Mehdi Fattahi, Mehdi Abbasi, H Zalaghi, A Eynalvandpour, A R Dabiri, Y FattahiAbstract:Abstract In the present study, a novel method for reducing diffusible hydrogen in the weld metals was developed by adding colloidal nanosilica to the Electrode Coating. Shielded metal arc weld deposits were prepared by varying colloidal nanosilica content in the range of 0–30 wt.%. The diffusible hydrogen and metallographic tests were carried out on the weld metals to evaluate the effect of colloidal nanosilica addition on the weld metal properties. The test results showed that the weld metal diffusible hydrogen content was greatly decreased when using the coated Electrodes containing colloidal nanosilica.
-
Effect of Ti-based inclusions and acicular ferrite on the corrosion performance of multipass weld metals
Materials Chemistry and Physics, 2014Co-Authors: Mehdi Fattahi, N Nabhani, E. Rafiee, Nasibi, E. Ahmadi, Y FattahiAbstract:Abstract This paper reports the effect of Ti-based inclusions and acicular ferrite on the corrosion performance of carbon steel multipass weld metals. The weld metals containing Ti-based inclusions have been prepared by addition of different quantities of titanium oxide nanoparticles to the Electrode Coating, which was dispersed using the ultrasonication process. After welding, the relationship between microstructure and corrosion performance of the weld metals was studied through full metallographic, potentiodynamic polarization and electrochemical impedance spectroscopy methods. It was observed that the use of titanium oxide nanoparticles in the coated Electrodes grain refined the weld metals, which is attributed to the beneficial role of nanostructured inclusions as heterogeneous nucleation sites of acicular ferrite. It was also deduced from the corrosion tests of the weld samples that increasing the Ti-based inclusion content and grain refinement can deteriorate the corrosion resistance of the weld metals.
-
Effect of Ti-containing inclusions on the nucleation of acicular ferrite and mechanical properties of multipass weld metals.
Micron (Oxford England : 1993), 2012Co-Authors: Mehdi Fattahi, N Nabhani, N Arabian, M. Hosseini, Ebrahim RahimiAbstract:In the present study, the influence of Ti-containing inclusions on the development of acicular ferrite microstructure and mechanical properties in the multipass weld metals has been studied. Shielded metal arc weld deposits were prepared by varying titanium content in the range of 0.003-0.021%. The variation in the titanium content was obtained by the addition of different amounts of titanium oxide nanoparticles to the Electrode Coating. The dispersion of titanium oxide nanoparticles, composition of inclusions, microstructural analysis, tensile properties and Charpy impact toughness were evaluated. As the amount of Ti-containing inclusions in the weld metal was increased, the microstructure of the weld metal was changed from the grain boundary allotriomorphic ferrite structure to acicular ferrite with the intragranular nucleation of ferrite on the Ti-containing inclusions, and the mechanical properties were improved. This improvement is attributable to the increased percentage of acicular ferrite due to the uniform dispersion of Ti-containing inclusions and the pinning force of oxide nanoparticles against the growth of allotriomorphic ferrite and Widmanstätten ferrite from the austenite grain boundaries.
-
improvement of impact toughness of aws e6010 weld metal by adding tio2 nanoparticles to the Electrode Coating
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Mehdi Fattahi, N Nabhani, M R Vaezi, Ebrahim RahimiAbstract:Abstract The effect of TiO 2 nanoparticles in the Electrode Coating on the impact toughness of three weld metals prepared by the shielded metal arc welding process was investigated and the main factors affecting the impact toughness were discussed. The microstructure, mechanical properties and fracture surface morphology of the weld metals have been evaluated and the results are compared. When the content of TiO 2 nanoparticles in the composition of Electrode Coating is increased, the morphology of ferrite in the microstructure of columnar zone will change from Widmanstatten ferrite to acicular ferrite. This finally changes to allotriomorphic ferrite when the amount of TiO 2 nanoparticles in the Electrode Coating goes relatively high. Furthermore, the addition of TiO 2 nanoparticles is effective in refining the ferrite grain size of the reheated microstructures of weld metals. This effect is attributed to the increased number of nucleation sites on the oxide nanoparticles. The impact toughness of the weld metal was improved by adding TiO 2 nanoparticles, especially when a medium TiO 2 nanoparticle content was used in the Electrode Coating. A significant increase in the impact toughness of weld metal was shown to be due to the increased percentage of acicular ferrite and refinement of microstructure.
Zhongxin Song - One of the best experts on this subject based on the ideXlab platform.
-
ultralow loading and high performing pt catalyst for a polymer electrolyte membrane fuel cell anode achieved by atomic layer deposition
ACS Catalysis, 2019Co-Authors: Zhongxin Song, Mohammad Norouzi Banis, Hanshuo Liu, Lei Zhang, Yang Zhao, Kieran Doyledavis, Shanna Knights, Gianluigi A Botton, Xueliang SunAbstract:Decreasing Pt loading in the anode layer below ∼0.025 mg·cm–2 is found to reduce the hydrogen oxidation reaction rate during polymer electrolyte membrane fuel cells (PEMFCs) normal operation, when using conventional Pt/C catalysts and Electrode Coating methods. To achieve extremely low Pt loading in the anode catalyst layer while maintaining high PEMFC performance and durability, a series of membrane Electrode assemblies (MEAs) with low Pt loading in the anode layer are successfully prepared using an atomic layer deposition (ALD) technique. When the ALD cycle number is controlled, the Pt nanoparticles (NPs) with different sizes and loadings are directly deposited on the carbon layer to form the anode catalyst layer. The ALDPt NPs with uniform particle sizes are highly distributed on the carbon surface, which promotes the ALDPt with high electrochemical active surface area and enables enhanced performance of ALDPt-MEAs. Particularly, the 50ALDPt-MEA with the anode Pt prepared by 50ALD cycles shows excellen...
-
Ultralow Loading and High-Performing Pt Catalyst for a Polymer Electrolyte Membrane Fuel Cell Anode Achieved by Atomic Layer Deposition
2019Co-Authors: Zhongxin Song, Mohammad Norouzi Banis, Hanshuo Liu, Lei Zhang, Yang Zhao, Kieran Doyle-davis, Shanna KnightsAbstract:Decreasing Pt loading in the anode layer below ∼0.025 mg·cm–2 is found to reduce the hydrogen oxidation reaction rate during polymer electrolyte membrane fuel cells (PEMFCs) normal operation, when using conventional Pt/C catalysts and Electrode Coating methods. To achieve extremely low Pt loading in the anode catalyst layer while maintaining high PEMFC performance and durability, a series of membrane Electrode assemblies (MEAs) with low Pt loading in the anode layer are successfully prepared using an atomic layer deposition (ALD) technique. When the ALD cycle number is controlled, the Pt nanoparticles (NPs) with different sizes and loadings are directly deposited on the carbon layer to form the anode catalyst layer. The ALDPt NPs with uniform particle sizes are highly distributed on the carbon surface, which promotes the ALDPt with high electrochemical active surface area and enables enhanced performance of ALDPt-MEAs. Particularly, the 50ALDPt-MEA with the anode Pt prepared by 50ALD cycles shows excellent H2–air PEMFC activity and durability. Importantly, the 20ALDPt-MEA with an ultralow anode Pt loading of 0.01 mg·cm–2 displays a significantly high surface area of 155 m2·g–1Pt, approximately 3 times higher than the 50.3 m2·g–1Pt for commercial Pt catalyst. The 20ALDPt anode also shows better stability than that of the commercial Pt/C during the anode potential cycling test. The ultralow Pt loading, uniform Pt distribution, high MEA performance, and durability achieved indicate that the ALD technique has great potential in developing high-performing electrocatalysts for PEMFC
Y Fattahi - One of the best experts on this subject based on the ideXlab platform.
-
reduction of weld metal diffusible hydrogen content by adding colloidal nanosilica to the Electrode Coating
International Journal of Hydrogen Energy, 2016Co-Authors: Mehdi Fattahi, Mehdi Abbasi, H Zalaghi, A Eynalvandpour, A R Dabiri, Y FattahiAbstract:Abstract In the present study, a novel method for reducing diffusible hydrogen in the weld metals was developed by adding colloidal nanosilica to the Electrode Coating. Shielded metal arc weld deposits were prepared by varying colloidal nanosilica content in the range of 0–30 wt.%. The diffusible hydrogen and metallographic tests were carried out on the weld metals to evaluate the effect of colloidal nanosilica addition on the weld metal properties. The test results showed that the weld metal diffusible hydrogen content was greatly decreased when using the coated Electrodes containing colloidal nanosilica.
-
Effect of Ti-based inclusions and acicular ferrite on the corrosion performance of multipass weld metals
Materials Chemistry and Physics, 2014Co-Authors: Mehdi Fattahi, N Nabhani, E. Rafiee, Nasibi, E. Ahmadi, Y FattahiAbstract:Abstract This paper reports the effect of Ti-based inclusions and acicular ferrite on the corrosion performance of carbon steel multipass weld metals. The weld metals containing Ti-based inclusions have been prepared by addition of different quantities of titanium oxide nanoparticles to the Electrode Coating, which was dispersed using the ultrasonication process. After welding, the relationship between microstructure and corrosion performance of the weld metals was studied through full metallographic, potentiodynamic polarization and electrochemical impedance spectroscopy methods. It was observed that the use of titanium oxide nanoparticles in the coated Electrodes grain refined the weld metals, which is attributed to the beneficial role of nanostructured inclusions as heterogeneous nucleation sites of acicular ferrite. It was also deduced from the corrosion tests of the weld samples that increasing the Ti-based inclusion content and grain refinement can deteriorate the corrosion resistance of the weld metals.
Ebrahim Rahimi - One of the best experts on this subject based on the ideXlab platform.
-
Effect of Ti-containing inclusions on the nucleation of acicular ferrite and mechanical properties of multipass weld metals.
Micron (Oxford England : 1993), 2012Co-Authors: Mehdi Fattahi, N Nabhani, N Arabian, M. Hosseini, Ebrahim RahimiAbstract:In the present study, the influence of Ti-containing inclusions on the development of acicular ferrite microstructure and mechanical properties in the multipass weld metals has been studied. Shielded metal arc weld deposits were prepared by varying titanium content in the range of 0.003-0.021%. The variation in the titanium content was obtained by the addition of different amounts of titanium oxide nanoparticles to the Electrode Coating. The dispersion of titanium oxide nanoparticles, composition of inclusions, microstructural analysis, tensile properties and Charpy impact toughness were evaluated. As the amount of Ti-containing inclusions in the weld metal was increased, the microstructure of the weld metal was changed from the grain boundary allotriomorphic ferrite structure to acicular ferrite with the intragranular nucleation of ferrite on the Ti-containing inclusions, and the mechanical properties were improved. This improvement is attributable to the increased percentage of acicular ferrite due to the uniform dispersion of Ti-containing inclusions and the pinning force of oxide nanoparticles against the growth of allotriomorphic ferrite and Widmanstätten ferrite from the austenite grain boundaries.
-
improvement of impact toughness of aws e6010 weld metal by adding tio2 nanoparticles to the Electrode Coating
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Mehdi Fattahi, N Nabhani, M R Vaezi, Ebrahim RahimiAbstract:Abstract The effect of TiO 2 nanoparticles in the Electrode Coating on the impact toughness of three weld metals prepared by the shielded metal arc welding process was investigated and the main factors affecting the impact toughness were discussed. The microstructure, mechanical properties and fracture surface morphology of the weld metals have been evaluated and the results are compared. When the content of TiO 2 nanoparticles in the composition of Electrode Coating is increased, the morphology of ferrite in the microstructure of columnar zone will change from Widmanstatten ferrite to acicular ferrite. This finally changes to allotriomorphic ferrite when the amount of TiO 2 nanoparticles in the Electrode Coating goes relatively high. Furthermore, the addition of TiO 2 nanoparticles is effective in refining the ferrite grain size of the reheated microstructures of weld metals. This effect is attributed to the increased number of nucleation sites on the oxide nanoparticles. The impact toughness of the weld metal was improved by adding TiO 2 nanoparticles, especially when a medium TiO 2 nanoparticle content was used in the Electrode Coating. A significant increase in the impact toughness of weld metal was shown to be due to the increased percentage of acicular ferrite and refinement of microstructure.
Xueliang Sun - One of the best experts on this subject based on the ideXlab platform.
-
ultralow loading and high performing pt catalyst for a polymer electrolyte membrane fuel cell anode achieved by atomic layer deposition
ACS Catalysis, 2019Co-Authors: Zhongxin Song, Mohammad Norouzi Banis, Hanshuo Liu, Lei Zhang, Yang Zhao, Kieran Doyledavis, Shanna Knights, Gianluigi A Botton, Xueliang SunAbstract:Decreasing Pt loading in the anode layer below ∼0.025 mg·cm–2 is found to reduce the hydrogen oxidation reaction rate during polymer electrolyte membrane fuel cells (PEMFCs) normal operation, when using conventional Pt/C catalysts and Electrode Coating methods. To achieve extremely low Pt loading in the anode catalyst layer while maintaining high PEMFC performance and durability, a series of membrane Electrode assemblies (MEAs) with low Pt loading in the anode layer are successfully prepared using an atomic layer deposition (ALD) technique. When the ALD cycle number is controlled, the Pt nanoparticles (NPs) with different sizes and loadings are directly deposited on the carbon layer to form the anode catalyst layer. The ALDPt NPs with uniform particle sizes are highly distributed on the carbon surface, which promotes the ALDPt with high electrochemical active surface area and enables enhanced performance of ALDPt-MEAs. Particularly, the 50ALDPt-MEA with the anode Pt prepared by 50ALD cycles shows excellen...