中文摘要：

采用极化曲线、循环伏安法研究了喷射电沉积制备纳米晶镍的阴极极化行为及其机理。并根据电化学测试结果,选取一定范围内的电流密度,利用扫描喷射电沉积在45钢基体表面制备了纳米镍涂层。用扫描电镜、X射线衍射仪和显微硬度计研究了电流密度对镍涂层表面形貌、微观组织结构、晶粒尺寸及表面显微硬度的影响,并进行了耐磨性试验。结果表明,喷射电沉积可以显著提高镍沉积的极限电流密度,并在高的过电位下促进晶体的形核,有利于获得纳米晶镍镀层;随着电流密度的增大,纳米晶镍的平均晶粒尺寸先变小再变大,当电流密度为130A/dm2时涂层最致密,平均晶粒尺寸最小,表面显微硬度也最高;经过喷射电沉积后,试样耐磨性能有了较大的提高。

英文摘要：

The cathodic polarization behavior and mechanism of jet-electrodeposited nanocrystalline Ni coating were studied by polarization curves and cyclic voltammetry experiments. According to the result of electrochemical test,a range of current densities were selected to prepare nanocrystalline Ni coating on 45 steel by scanning jet-electrodeposition. The characteristics of nanocrystalline Ni coating under various current densities,surface morphology, microstructure,grain size and microhardness were investigated by scanning electron microscope （ SEM） ,X-ray diffraction （ XRD） ,and microhardness tester,respectively,then followed by wear resistance test. The result shows that jet-electrodeposition can significantly improve the limited current density of Ni deposition,and has an high overpotential to promote crystal nucleation. It is advantageous to the production of nanocrystalline nickel. As current density increases,the average grain size of nanocrystalline nickel first decreases then increases. The coating is the densest when the current density is 130 A/dm2,with the smallest average grain size and highest surface microhardness. Wear resistance is also enhanced after jet-electrodeposition.