The friction and wear behavior of Fe Al intermetallics based coating produced by high velocity arc spraying technique under dry sliding at room temperature were investigated using a ball on disc tribotester. The ef...The friction and wear behavior of Fe Al intermetallics based coating produced by high velocity arc spraying technique under dry sliding at room temperature were investigated using a ball on disc tribotester. The effect of sliding speed on friction coefficient and wear of the coating was studied. The worn surface of the coating was analyzed by scanning electron microscope (SEM) to explore sliding friction and wear mechanism. The results show that the variations of friction coefficient can be divided into three distinct steps during the trail. Both the friction coefficient and the wear of the coating increase with increased sliding speed due to accelerated crack propagation rate and lamellar structure with poor ductility of the coating. The coating surface is subjected to alternately tensile stress and compression stress during sliding wear process, and the predominant wear mechanism of the coatings appears to be brittle fracture and delamination.展开更多
The electrochemical nucleation mechanism of nickel on the vitreous carbon electrode from n-Al2O3/Ni composite brush plating system was investigated using potential step method. The interaction between nano-alumina and...The electrochemical nucleation mechanism of nickel on the vitreous carbon electrode from n-Al2O3/Ni composite brush plating system was investigated using potential step method. The interaction between nano-alumina and matrix metal was researched by X-ray photoelectron spectrometry. The results show that the nano-alumina leads to the increasing of the nuclei density, nucleation rate constant and crystal growth rate during nickel electrocrystallization. Nano-alumina is found to be beneficial for nucleation and growth of nickel. During the electrodeposition process, some nanoparticles are captured effectively on the growing metal surface. As the absorbed nickel atoms are diffusing on electrode surface, some of them arrive at the interface between the captured nano-alumina and the growing metal surface. The unsaturated bond of oxygen on nano-alumina surface can capture some of the absorbed nickel atoms and form nickel-oxygen chemical bond. The new nucleation and growth sites of nickel atoms appear at the interfaces between nanoparticles and metal growing surface. Nanoparticles are embedded gradually in the newly deposited nickel atoms, which leads to the formation of the composite coating. The results indicate that the nano-alumina takes part in the electrode reaction and the unsaturated chemical bond of oxygen on nanoparticle surface can combine with the absorbed nickel atoms by way of chemical bond.展开更多
An experimental study has been carried out to investigate the influence of heat treatment at 300 ℃,450 ℃,550 ℃,650 ℃ and 800 ℃ on the microstructure and sliding wear behavior of Fe Al/WC intermetallic composite c...An experimental study has been carried out to investigate the influence of heat treatment at 300 ℃,450 ℃,550 ℃,650 ℃ and 800 ℃ on the microstructure and sliding wear behavior of Fe Al/WC intermetallic composite coatings produced by high velocity arc spraying (HVAS) and cored wires. The result shows, the main phases in both as sprayed and heat treated Fe Al/WC composite coatings are iron aluminide intermetallics (Fe 3Al+FeAl) and α as well as a little oxide (Al 2O 3) and carbides (WC, W 2C, Fe 2W 2C and Fe 6W 6C). After heat treated at 450-650 ℃, dispersion strengthening of Fe 2W 2C and Fe 6W 6C will lead to a rise in microhardness of the coatings. The microhardness is likely to be the most important factor which influences the sliding wear behavior of the coatings. Increasing the microhardness through heat treatment will improve the sliding wear resistance of the Fe Al/WC composite coatings.展开更多
基金NationalNatureScienceFoundationofChina (No .5 0 0 0 5 0 2 4)
文摘The friction and wear behavior of Fe Al intermetallics based coating produced by high velocity arc spraying technique under dry sliding at room temperature were investigated using a ball on disc tribotester. The effect of sliding speed on friction coefficient and wear of the coating was studied. The worn surface of the coating was analyzed by scanning electron microscope (SEM) to explore sliding friction and wear mechanism. The results show that the variations of friction coefficient can be divided into three distinct steps during the trail. Both the friction coefficient and the wear of the coating increase with increased sliding speed due to accelerated crack propagation rate and lamellar structure with poor ductility of the coating. The coating surface is subjected to alternately tensile stress and compression stress during sliding wear process, and the predominant wear mechanism of the coatings appears to be brittle fracture and delamination.
基金Project(50235030) supported by the National Natural Science Foundation of China Project(G1999065009) supported bythe National Key Fundamental Project of China Project(2002 M3) supported by the Cooperative Foundation of Science and Technology ofSino-Britain Government
文摘The electrochemical nucleation mechanism of nickel on the vitreous carbon electrode from n-Al2O3/Ni composite brush plating system was investigated using potential step method. The interaction between nano-alumina and matrix metal was researched by X-ray photoelectron spectrometry. The results show that the nano-alumina leads to the increasing of the nuclei density, nucleation rate constant and crystal growth rate during nickel electrocrystallization. Nano-alumina is found to be beneficial for nucleation and growth of nickel. During the electrodeposition process, some nanoparticles are captured effectively on the growing metal surface. As the absorbed nickel atoms are diffusing on electrode surface, some of them arrive at the interface between the captured nano-alumina and the growing metal surface. The unsaturated bond of oxygen on nano-alumina surface can capture some of the absorbed nickel atoms and form nickel-oxygen chemical bond. The new nucleation and growth sites of nickel atoms appear at the interfaces between nanoparticles and metal growing surface. Nanoparticles are embedded gradually in the newly deposited nickel atoms, which leads to the formation of the composite coating. The results indicate that the nano-alumina takes part in the electrode reaction and the unsaturated chemical bond of oxygen on nanoparticle surface can combine with the absorbed nickel atoms by way of chemical bond.
文摘An experimental study has been carried out to investigate the influence of heat treatment at 300 ℃,450 ℃,550 ℃,650 ℃ and 800 ℃ on the microstructure and sliding wear behavior of Fe Al/WC intermetallic composite coatings produced by high velocity arc spraying (HVAS) and cored wires. The result shows, the main phases in both as sprayed and heat treated Fe Al/WC composite coatings are iron aluminide intermetallics (Fe 3Al+FeAl) and α as well as a little oxide (Al 2O 3) and carbides (WC, W 2C, Fe 2W 2C and Fe 6W 6C). After heat treated at 450-650 ℃, dispersion strengthening of Fe 2W 2C and Fe 6W 6C will lead to a rise in microhardness of the coatings. The microhardness is likely to be the most important factor which influences the sliding wear behavior of the coatings. Increasing the microhardness through heat treatment will improve the sliding wear resistance of the Fe Al/WC composite coatings.
