Pure nickel and Ni/Ti3Si（AI）C2 composite coatings were prepared by electrodeposition method from an additive-free nickel Watt＇s bath and were characterized by X-ray diffraction, laser confocal microscopy and scanni...Pure nickel and Ni/Ti3Si（AI）C2 composite coatings were prepared by electrodeposition method from an additive-free nickel Watt＇s bath and were characterized by X-ray diffraction, laser confocal microscopy and scanning electron microscopy. The effect of current and Ti3Si（AI）C2 concentration in the solution on the composition, grain size, preferred orientation and surface morphology of the electrodeposited coatings were investigated. （200）-oriented Ni coatings could be deposited at high current （62.5 mA）, while （220）-oriented Ni coatings could be obtained at low current （25 mA）. However, the presence of Ti3Si（Al）C2 particles disturbed the surface texture of Ni crystallites in the composite coatings. Based on the simulated morphology and the observed microstructure, the mechanisms for the change of preferred orientation and crystallite shapes in the presence of Ti3Si（Al）C2 particles were discussed. Moreover, microhardness and friction properties of pure nickel and Ni/Ti3Si（Al）C2 composite coatings were also compared.展开更多
The high temperature oxidation resistance of RE Ni W B B 4C MoS 2 composite coating, the effects of electrodeposition conditions on the morphologies of the coating and the effect of heat treatment temperature on its h...The high temperature oxidation resistance of RE Ni W B B 4C MoS 2 composite coating, the effects of electrodeposition conditions on the morphologies of the coating and the effect of heat treatment temperature on its hardness, abrasion resistance and phase structure were investigated by using scanning electron microscope(SEM), X ray diffractometer, microhardness tester and abrasion machine. The results show that the oxidation degree of RE Ni W B B 4C MoS 2 composite coating is small when the temperature is lower than 700 ℃, but it increases sharply when the temperature is higher than 700 ℃. The hardness of RE Ni W B B 4C MoS 2 composite coating increases with increasing heat treatment temperature, it comes up to the maximum value at 400 ℃,but it decreases gradually if the temperature rises continuously. The most favourable abrasion resistance was attained after RE Ni W B B 4C MoS 2 composite coating being heat treated at 400 ℃. Without heat treating, it is mainly amorphous and partially crystallized, but wholly crystallized after being heat treated at 500 ℃. RE in the composite coating is in the form of CeO 2 and additions of CeO 2 and B 4C can enhance the thermostability of RE Ni W B B 4C MoS 2 composite coating.展开更多
The morphology and corrosion behavior of Ni/Al2O3 composite coatings prepared using double-pulsed electrodepositing technique after oxidized under 800 ℃ NaCl deposit in air environment were analyzed by scanning elect...The morphology and corrosion behavior of Ni/Al2O3 composite coatings prepared using double-pulsed electrodepositing technique after oxidized under 800 ℃ NaCl deposit in air environment were analyzed by scanning electrical microscope (SEM), X-ray diffraction(XRD) and energy dispersive spectrum(EDS). The results showed that the corrosion of all composite coatings was accelerated under NaCl deposits, and the corrosion products were rather porous with poor adherence to the matrix. Al2O3 particles in the coatings can refine the grain size and improve the high temperature corrosion resistance of the coatings. Within the test scope, the more Al2O3 particles in the coatings, the lower corrosion rates could be obtained, and the corrosion mechanism was also discussed.展开更多
基金supported by the National Outstanding Young Scientist Foundation for Y. C. Zhou, Natural Sciences Foundation of China under Grant Nos. 50232040, 50302011, 90403027, 50772114 and 50832008
文摘Pure nickel and Ni/Ti3Si（AI）C2 composite coatings were prepared by electrodeposition method from an additive-free nickel Watt＇s bath and were characterized by X-ray diffraction, laser confocal microscopy and scanning electron microscopy. The effect of current and Ti3Si（AI）C2 concentration in the solution on the composition, grain size, preferred orientation and surface morphology of the electrodeposited coatings were investigated. （200）-oriented Ni coatings could be deposited at high current （62.5 mA）, while （220）-oriented Ni coatings could be obtained at low current （25 mA）. However, the presence of Ti3Si（Al）C2 particles disturbed the surface texture of Ni crystallites in the composite coatings. Based on the simulated morphology and the observed microstructure, the mechanisms for the change of preferred orientation and crystallite shapes in the presence of Ti3Si（Al）C2 particles were discussed. Moreover, microhardness and friction properties of pure nickel and Ni/Ti3Si（Al）C2 composite coatings were also compared.
文摘The high temperature oxidation resistance of RE Ni W B B 4C MoS 2 composite coating, the effects of electrodeposition conditions on the morphologies of the coating and the effect of heat treatment temperature on its hardness, abrasion resistance and phase structure were investigated by using scanning electron microscope(SEM), X ray diffractometer, microhardness tester and abrasion machine. The results show that the oxidation degree of RE Ni W B B 4C MoS 2 composite coating is small when the temperature is lower than 700 ℃, but it increases sharply when the temperature is higher than 700 ℃. The hardness of RE Ni W B B 4C MoS 2 composite coating increases with increasing heat treatment temperature, it comes up to the maximum value at 400 ℃,but it decreases gradually if the temperature rises continuously. The most favourable abrasion resistance was attained after RE Ni W B B 4C MoS 2 composite coating being heat treated at 400 ℃. Without heat treating, it is mainly amorphous and partially crystallized, but wholly crystallized after being heat treated at 500 ℃. RE in the composite coating is in the form of CeO 2 and additions of CeO 2 and B 4C can enhance the thermostability of RE Ni W B B 4C MoS 2 composite coating.
文摘The morphology and corrosion behavior of Ni/Al2O3 composite coatings prepared using double-pulsed electrodepositing technique after oxidized under 800 ℃ NaCl deposit in air environment were analyzed by scanning electrical microscope (SEM), X-ray diffraction(XRD) and energy dispersive spectrum(EDS). The results showed that the corrosion of all composite coatings was accelerated under NaCl deposits, and the corrosion products were rather porous with poor adherence to the matrix. Al2O3 particles in the coatings can refine the grain size and improve the high temperature corrosion resistance of the coatings. Within the test scope, the more Al2O3 particles in the coatings, the lower corrosion rates could be obtained, and the corrosion mechanism was also discussed.
