电沉积方式对Ni-nanoAl2 O3复合镀层组织结构和耐蚀性能的影响

Effects of Different Electro-deposition Methods on Microstructure and Corrosion Resistance of Ni-nanoAl_2O_3 Composite Coating

利用直流、单脉冲和双脉冲电沉积制取Ni-nanoAl2O3复合镀层。研究电镀方式对复合镀层组织结构和耐蚀性的影响,并用扫描电子显微镜、透射电子显微镜和X射线衍射等测试方法分析Ni-nanoAl2O3复合镀层的截面形貌和组织结构。测量试样在质量分数3.5%NaCl溶液中的耐蚀性能。研究结果表明,制备方法对镀层基质金属晶粒尺寸有较大影响,表现在双脉冲电沉积获得的复合镀层基质金属的晶粒最小为24 nm左右,直流复合镀层基质金属的晶粒最大为38 nm;3种方法获得的粒子含量相近的复合镀层双脉冲镀层耐蚀性能最好即Icorr=2.8×10-7A,Ecorr=-0.225 V,直流镀层最差即Icorr=3.16×10-6A,Ecorr=-0.328 V。

Composite coatings of Ni-nanoAl2O3 were obtained by direct current （DC）, pulse current （PC） and pulse reverse current（PRC） electro deposition techniques. The effects of different coating methods on the structure of the composite coating were studied and the cross-section morphology and microstructure of the Ni-nanoAl2O3 were analyzed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and XRD. Corrosion resistance of the coating to 3. 5% NaCl solution was performed. The resuh showed that the prep method can significantly affect the coating microstructure and matrix grain size. The minimum size of the metal matrix Ni grains in the composition coating obtained by PRC deposition was approximately 24 nm, while the maximum grain size of Ni obtained by DC was abOUt 38 nm. Polarization test indicated that the corrosion resist- ance of the composite coating Ni-nano Al2O3 deposited by PRC was the optimal one, while that by DC was the worst. The corrosion current and corrosion voltage were 2. 8 × 10^-7 A and -0. 225 V for composite coating Ni-nanoAl2O3 deposited by PRC, and 3. 16 × 10^-6 A and -0. 328 V for that deposited by the latter,respectively.