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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。
Preparation of Ni-P / n-CeO2 Nano-composite Coating by Double Pulse Current Characteristics and Ultrasonic Oscillatory Effect Electrodeposition. The morphology, chemical composition and crystal structure of the coatings were analyzed by means of E-SEM / EDXA, TEM and X-ray diffractometer (XRD). The results show that the Ce content and deposition rate can reach 2.3% and 68μm / h respectively with 15g / L nano-CeO2 (RE) particles. The grains are dense and amorphous. The microhardness of the coating is up to HV780. The effects of nano-rare earth particles adsorption characteristics and pulse overpotential on the electrodeposition mechanism were discussed. Ce4 + or n-CeO2 adsorbed on the active surface of the cathode to form a large number of catalytic nuclei, deposited and pinned at the edge of the cracked fission source. At high temperature aging, the nano-particles and some Ni grains are fully dispersed and miscible, taking up space and hindering grain coarsening and crack propagation, thus effectively improving crack propagation resistance and microhardness of the composite coating.