The stability of the electrodeposited amorphous Ni-Fe-P alloys was studied by DTA,DSC,XRD and improved four-ball wear tester in order to clear its applied scope.The results show that the element content has influence ...The stability of the electrodeposited amorphous Ni-Fe-P alloys was studied by DTA,DSC,XRD and improved four-ball wear tester in order to clear its applied scope.The results show that the element content has influence on the stability of amorphous Ni-Fe-P alloy,in which the crystallization temperature increases with Fe content,and the increase of P content delays the appearance of stable crystallization phases and recrystallization.There exist 6 exothermal reactions during heating the amorphous Ni69Fe8P23 alloy continuously.The activation energies of exothermal reactions at 248,303,322,350,376 and 442 ℃ are 131.5,111.6,237.8,253.6 and 238.5 kJ/mol,respectively.The amorphous Ni60Fe22P18 alloy crystallizes when the heating temperature is beyond 250 ℃.The stable crystallization phases consist of Ni(Fe)and Ni3P-type compounds Ni3P,Fe3P,(Fe,Ni)3P.The pressure and fraction have influence on the stability of amorphous alloy.Rubbing above the critical pressure crystallization will take place on the fractional surface.The crystallization phases due to pressure and fraction are different from those due to heating.It is the crystallization that increases the wear resistance of Ni-Fe-P coating under higher pressure.展开更多
Ni-Fe-Mo-Co alloy electrode was prepared in a citrate solution by electrodeposition, and then Mo and Fe were partially leached out from the electrode in 30% KOH solution. The unique surface micromorphology of a hive-l...Ni-Fe-Mo-Co alloy electrode was prepared in a citrate solution by electrodeposition, and then Mo and Fe were partially leached out from the electrode in 30% KOH solution. The unique surface micromorphology of a hive-like structure was obtained with an average pore size of about 50 nm. The electrode has a very large real surface area and a stable structure. The effects of sodium molybdate concentration on the composition, surface morphology, and structure of electrodes were analyzed by EDS, SEM and XRD. The polarization curves of the different electrodes show that the catalytic activity of electrodes is strongly correlated with the mole fraction of alloy elements (Ni, Fe, Mo, Co), and the addition of cobalt element to Ni-Fe-Mo alloy improves the catalytic activity. The Ni35.63Fe24.67Mo23.52Co16.18 electrode has the best activity for hydrogen evolution reaction(HER), with an over-potential of 66.2 mV, in 30% KOH at 80 ℃ and 200 mA/cm2. The alloy maintains its good catalytic activity for HER during continuous or intermittent electrolysis. Its electrochemical activity and catalytic stability are much higher than the other iron-group with Mo alloy electrodes.展开更多
基金Project(E0410014) supported by the National Science Foundation of Fujian Province,China
文摘The stability of the electrodeposited amorphous Ni-Fe-P alloys was studied by DTA,DSC,XRD and improved four-ball wear tester in order to clear its applied scope.The results show that the element content has influence on the stability of amorphous Ni-Fe-P alloy,in which the crystallization temperature increases with Fe content,and the increase of P content delays the appearance of stable crystallization phases and recrystallization.There exist 6 exothermal reactions during heating the amorphous Ni69Fe8P23 alloy continuously.The activation energies of exothermal reactions at 248,303,322,350,376 and 442 ℃ are 131.5,111.6,237.8,253.6 and 238.5 kJ/mol,respectively.The amorphous Ni60Fe22P18 alloy crystallizes when the heating temperature is beyond 250 ℃.The stable crystallization phases consist of Ni(Fe)and Ni3P-type compounds Ni3P,Fe3P,(Fe,Ni)3P.The pressure and fraction have influence on the stability of amorphous alloy.Rubbing above the critical pressure crystallization will take place on the fractional surface.The crystallization phases due to pressure and fraction are different from those due to heating.It is the crystallization that increases the wear resistance of Ni-Fe-P coating under higher pressure.
基金Project(20374021) supported by the National Natural Science Foundation of China
文摘Ni-Fe-Mo-Co alloy electrode was prepared in a citrate solution by electrodeposition, and then Mo and Fe were partially leached out from the electrode in 30% KOH solution. The unique surface micromorphology of a hive-like structure was obtained with an average pore size of about 50 nm. The electrode has a very large real surface area and a stable structure. The effects of sodium molybdate concentration on the composition, surface morphology, and structure of electrodes were analyzed by EDS, SEM and XRD. The polarization curves of the different electrodes show that the catalytic activity of electrodes is strongly correlated with the mole fraction of alloy elements (Ni, Fe, Mo, Co), and the addition of cobalt element to Ni-Fe-Mo alloy improves the catalytic activity. The Ni35.63Fe24.67Mo23.52Co16.18 electrode has the best activity for hydrogen evolution reaction(HER), with an over-potential of 66.2 mV, in 30% KOH at 80 ℃ and 200 mA/cm2. The alloy maintains its good catalytic activity for HER during continuous or intermittent electrolysis. Its electrochemical activity and catalytic stability are much higher than the other iron-group with Mo alloy electrodes.
