Microstructure and depositional mechanism of Ni-P coatings with nano-ceria particles by pulse electrodeposition  

纳米稀土颗粒CeO_2掺杂对Ni-P脉冲镀层微观结构与沉积机理的影响(英文)

作　　者：周小卫[1] 沈以赴[1] 靳惠明[2] 郑莹莹[1] 

机构地区：[1]南京航空航天大学材料科学与技术学院,南京210016 [2]扬州大学机械工程学院,扬州225127

出　　处：《Transactions of Nonferrous Metals Society of China》2012年第8期1981-1988,共8页中国有色金属学报（英文版）

基　　金：Project (CXLX12_0151) supported by Jiangsu Innovation program for Graduate Education and Fundamental Research Funds for Central Unibersities, China

摘　　要：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.利用双脉冲电流特性与超声场高频振荡效应电沉积法制备Ni-P/n-CeO2纳米复合镀层。借助环境扫描电镜(E-SEM/EDXA)、透射电子显微镜(TEM)及X射线衍射仪(XRD),对镀层微观形貌、化学成分及晶体结构进行分析。结果表明:掺杂15g/L纳米CeO2(RE)颗粒,稀土Ce含量与沉积速度分别可达2.3%和68μm/h,晶粒致密,呈现非晶态;在600°C下时效处理2h,复合镀层的显微硬度高达HV780。讨论了纳米稀土颗粒吸附特性与脉冲过电势对电沉积机理的影响。Ce4+或n-CeO2吸附在阴极活性表面形成大量具有催化作用的晶核,沉积并钉扎在开裂的纹裂源边缘。在高温时效时,纳米颗粒与部分Ni晶粒充分弥散互溶,占据空间,阻碍晶粒粗化及裂纹扩展,从而有效提高复合镀层的裂纹扩展抗力与显微硬度。

关 键 词：Ni-P coating pulse electrodeposition OVERPOTENTIAL depositional mechanism CEO2 

分 类 号：TG174.44[金属学及工艺—金属表面处理]