纳米陶瓷颗粒的电催化效应及其在复合刷镀层中的化学状态

采用循环伏安法和电位阶跃法研究了nano-Al₂O₃ / Ni复合电刷镀体系的电化学响应，探讨了纳米颗粒对复合电沉积的影响；用X射线光电子谱研究了复合镀层中nano-Al₂O₃颗粒与基质金属之间的相互作用。结果表明纳米颗粒能使金属沉积过电位显著降低，电流效率、金属成核率及晶体生长速度增加，从而对金属镍的电结晶表现出明显的催化效应；在金属镍电结晶过程中，部分到达阴极附近的nano-Al₂O₃颗粒被电极表面捕获。金属生长面上的吸附态镍原子到达纳米颗粒与电极表面接触处，与该处纳米颗粒表面的不饱和氧原子形成Ni-O化学键，纳米颗粒与基质镍以化学键形式结合。纳米颗粒与电极表面的结合区域成为新的成核或生长中心，在随后的刷镀过程中纳米颗粒逐渐被电沉积的金属镍包埋，从而形成复合镀层。

Electrocatalytic Effect of Ceramic Nanoparticles and Chemical Binding Interaction between Nanoparticles and Matrix Metal in Composite Coating

The electrochemistry performance of nano-Al₂O₃ / Ni composite brush plating system is investigated by linear sweep voltammetry and potential step method. The interaction between nanoparticles and matrix metal nickel is studied by X-ray photoelectron spectrometry. The results show that the nanoparticles take part in electrocrystallization, decrease the deposition overpotential and enhance the current efficiency, nucleation and crystal growth rate. The nanoparticles can also catalyze the nickel electrodeposition and reduce the size of the metal grain. During electrocrystallization process, some of namnoparticles are captured effectively on the growing metal surface. As the absorbed nickel atoms are diffusing on metal growth surface, some of them arrive at the interface between the captured nanoparticles and the growing metal surface. The unsaturated bond of oxygen on nanoparticles surface can interact with the absorbed nickel atoms and form nickel-oxygen chemical bond. The new sites of nucleation and growth of nickel atom are arisen at the interface between nanoparticles and metal growing surface. And the nanoparticles are embedded gradually in newly deposited nickel atoms. As a result, the composite coating is formed.