The formation mechanism of the amorphous Ni-Fe-P coating was studied by analysis of the forming thermodynamics, dynamics, and crystallography of the amorphous alloy. The results show that, in the initial stage of depo...The formation mechanism of the amorphous Ni-Fe-P coating was studied by analysis of the forming thermodynamics, dynamics, and crystallography of the amorphous alloy. The results show that, in the initial stage of deposition a thin 'crystal epitaxial growth' layer first forms, and then transforms to amorphous gradually. The cross section in Ni-Fe-P coatings by electrolytic etching exhibits a banded structure of alternate dark and light bands. It is proposed that the banded structure is caused by a change in the P content with thickness,which is due to alternated depletion and enrichment of [OH-] in the diffusion layer resulting from the generation and evolution of hydrogen gas. The amorphous Ni-Fe-P coating will be formed in proper composition, high nucleation rate and strongly hindered growth of the crystal nucleus. Amorphous Ni-Fe-P alloys form as islands, and grow up by layer.展开更多
In the present paper, one hundred cluster models NinBP （n = 1-6） have been designed and studied by density functional theory （DFT） to get an insight into the local structure, catalytic properties and sulfur resist...In the present paper, one hundred cluster models NinBP （n = 1-6） have been designed and studied by density functional theory （DFT） to get an insight into the local structure, catalytic properties and sulfur resistibility of amorphous alloy Ni-B-P. The configurations in triplet state are found more stable than those in the singlet state. It is found： that as the content of Ni in the clusters increases, the value of Fermi level in clusters fluctuated, which shows that the content of Ni can influence the Fermi level to a certain extent. Based on the Fermi level and DOS, we consider the activity of catalyst in hydrogenation reaction is the best in cluster Ni3BP. On the basis of the charge of clusters NinBP （n = 1 -6）, we conclude the amorphous alloy Ni-B-P with high Ni content has better sulfur resistibility and the best hydrogenation activity, strong sulfur resistibility appears in clusters Ni3BP, and the amorphous alloy Ni60B20P20 with similar proportion is expected to prepare in the future.展开更多
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
The wear mechanism of amorphous Ni-Fe-P coating was discussed. The wear resistance of the amorphous Ni-Fe-P coatings was tested on a Timken wear apparatus, and the wear track of the amorphous Ni-Fe-P coatings as-depos...The wear mechanism of amorphous Ni-Fe-P coating was discussed. The wear resistance of the amorphous Ni-Fe-P coatings was tested on a Timken wear apparatus, and the wear track of the amorphous Ni-Fe-P coatings as-deposited and heated at various temperatures was observed by SEM. The results show that the wear resistance reaches a maximum value at NaHPO2·H2O concentration of 5 g/L, and heating at 400 ℃. The wear mode of the coating will change with the heating temperature increasing from pitting+plowing at 200 ℃ to pitting at 400 ℃, and to plowing at 600 ℃. The pits on the worn surface of the amorphous Ni-Fe-P coating result from the tribo-fatigue fracture. The cracks of spalling initiate at pits and propagate at certain angle with the sliding direction on surface, and then extend into sub-surface along the poor P layers or the interface between layers. Finally under repeated action of the stress in the rubbing process the cracks meet and the debris forms. The generation of the pits and spalling is related with the internal stress, brittleness and layer structure of the amorphous Ni-Fe-P coating.展开更多
The influences of heat treatment time on structure and the electrochemical behavior of electro-deposited amorphous Ni-P alloy coating were studied. The results show that the as-plated deposits have an amorphous struct...The influences of heat treatment time on structure and the electrochemical behavior of electro-deposited amorphous Ni-P alloy coating were studied. The results show that the as-plated deposits have an amorphous structure, and the deposits crystallize into Ni12P5 and Ni3P at 260 °C, and the corrosion resistance of the as-plated deposits are better than that of the deposits after heat treatment.展开更多
Experiments clarified that application of the maximum entropy method to calculate the RDF (radial distribution function)of the Ni-P amorphous alloy from fewer data of its X-ray diffraction data shows a higher resoluti...Experiments clarified that application of the maximum entropy method to calculate the RDF (radial distribution function)of the Ni-P amorphous alloy from fewer data of its X-ray diffraction data shows a higher resolution and good consistent with known results.It is be- lieved that this method is available for the analysis of amorphous structure.展开更多
The viscous flow of amorphous alloys near T_gis closely related to the viscosity of liquid alloys. On the basis of the measured surface tension and density for Ni-P binary alloys,the correla- tion between the viscosit...The viscous flow of amorphous alloys near T_gis closely related to the viscosity of liquid alloys. On the basis of the measured surface tension and density for Ni-P binary alloys,the correla- tion between the viscosity of the melt and viscous flow process of the amorphous alloy is inves- tigated.The relationship between viscosity and temperature for Ni-P alloys going from liquid to amorphous solid may be described by the following formula:展开更多
文摘The formation mechanism of the amorphous Ni-Fe-P coating was studied by analysis of the forming thermodynamics, dynamics, and crystallography of the amorphous alloy. The results show that, in the initial stage of deposition a thin 'crystal epitaxial growth' layer first forms, and then transforms to amorphous gradually. The cross section in Ni-Fe-P coatings by electrolytic etching exhibits a banded structure of alternate dark and light bands. It is proposed that the banded structure is caused by a change in the P content with thickness,which is due to alternated depletion and enrichment of [OH-] in the diffusion layer resulting from the generation and evolution of hydrogen gas. The amorphous Ni-Fe-P coating will be formed in proper composition, high nucleation rate and strongly hindered growth of the crystal nucleus. Amorphous Ni-Fe-P alloys form as islands, and grow up by layer.
基金University of Science and Technology Liaoning Research Project (No. 2003001)
文摘In the present paper, one hundred cluster models NinBP （n = 1-6） have been designed and studied by density functional theory （DFT） to get an insight into the local structure, catalytic properties and sulfur resistibility of amorphous alloy Ni-B-P. The configurations in triplet state are found more stable than those in the singlet state. It is found： that as the content of Ni in the clusters increases, the value of Fermi level in clusters fluctuated, which shows that the content of Ni can influence the Fermi level to a certain extent. Based on the Fermi level and DOS, we consider the activity of catalyst in hydrogenation reaction is the best in cluster Ni3BP. On the basis of the charge of clusters NinBP （n = 1 -6）, we conclude the amorphous alloy Ni-B-P with high Ni content has better sulfur resistibility and the best hydrogenation activity, strong sulfur resistibility appears in clusters Ni3BP, and the amorphous alloy Ni60B20P20 with similar proportion is expected to prepare in the future.
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.
文摘The wear mechanism of amorphous Ni-Fe-P coating was discussed. The wear resistance of the amorphous Ni-Fe-P coatings was tested on a Timken wear apparatus, and the wear track of the amorphous Ni-Fe-P coatings as-deposited and heated at various temperatures was observed by SEM. The results show that the wear resistance reaches a maximum value at NaHPO2·H2O concentration of 5 g/L, and heating at 400 ℃. The wear mode of the coating will change with the heating temperature increasing from pitting+plowing at 200 ℃ to pitting at 400 ℃, and to plowing at 600 ℃. The pits on the worn surface of the amorphous Ni-Fe-P coating result from the tribo-fatigue fracture. The cracks of spalling initiate at pits and propagate at certain angle with the sliding direction on surface, and then extend into sub-surface along the poor P layers or the interface between layers. Finally under repeated action of the stress in the rubbing process the cracks meet and the debris forms. The generation of the pits and spalling is related with the internal stress, brittleness and layer structure of the amorphous Ni-Fe-P coating.
文摘The influences of heat treatment time on structure and the electrochemical behavior of electro-deposited amorphous Ni-P alloy coating were studied. The results show that the as-plated deposits have an amorphous structure, and the deposits crystallize into Ni12P5 and Ni3P at 260 °C, and the corrosion resistance of the as-plated deposits are better than that of the deposits after heat treatment.
文摘Experiments clarified that application of the maximum entropy method to calculate the RDF (radial distribution function)of the Ni-P amorphous alloy from fewer data of its X-ray diffraction data shows a higher resolution and good consistent with known results.It is be- lieved that this method is available for the analysis of amorphous structure.
文摘The viscous flow of amorphous alloys near T_gis closely related to the viscosity of liquid alloys. On the basis of the measured surface tension and density for Ni-P binary alloys,the correla- tion between the viscosity of the melt and viscous flow process of the amorphous alloy is inves- tigated.The relationship between viscosity and temperature for Ni-P alloys going from liquid to amorphous solid may be described by the following formula:
