中國有色金屬學報(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 22 No. 8 August 2012 |
（1. College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics,
Nanjing 210016, China;
2. College of Mechanical Engineering, Yangzhou University, Yangzhou 225127, China）
Abstract:Nano-CeO2 (RE) particles were co-deposited into Ni-P binary composite coatings by applying pulse current (PC) under ultrasonic (U) field. Morphology, chemical content and crystal microstructure were characterized by environmental scanning electron microscopy (E-SEM) with energy dispersive X-ray analysis (EDXA), XRD diffractometry and transmission electron microscopy (TEM). Experimental results show that Ni-P coating reinforced with 15g/L nano-CeO2, in amorphous state and with compact structure, can be improved in the microhardness from HV0.2580 to HV0.2780 by annealing at 600 °C for 2 h. The highest content of codeposited Ce and deposition rate can reach 2.3% and 68 μm/h, respectively. Furthermore, the effect of RE adsorption and pulse overpotential on depositional mechanism was investigated. n-CeO2 particles or Ce4+ ions with strong adsorption capacity acted as the catalytic nucleus to improve densification effectively. During annealing at 600 °C for 2 h, n-CeO2 particles will uniformly adsorb on crystal grain to preferentially pad and heal up gaps of cracking Ni boundaries, promoting dispersion strengthening with refiner-grained structure.
Key words: Ni-P coating; pulse electrodeposition; overpotential; depositional mechanism; CeO2
