Nickel coatings with different microstructures were synthesized by pulse jet electrodeposition technique.Their morphology and microstructure were investigated by scanning electron microscopy（SEM）and transmission electron microscopy（TEM）.The corrosion property of the coatings was studied by using polarization,electrochemical impedance spectroscopy（EIS）,potential of zero free charge（PZFC） measurements and Mott-Schottky（M-S） relationship.The results showed that the coating with grain size of 50 nm possessed higher corrosion resistance than that with grain size of 10 nm.This abnormal behavior may be related to the existence of nanoscale twins in the coatings and the lower concentration of acceptor in the passive films.
Guozhe MengYang LiYawei ShaoTao ZhangYanqiu WangFuhui WangXuequn ChengChaofang DongXiaogang Li
The corrosion behavior of 316L stainless steel （31 6L SS） has been investigated in solutions containing various concentrations of chloride ions by using potentiodynamic polarization, capacitance measurement and Mott- Schottky relationship analysis （M-S）. The result indicates that passive currents change slightly with the addition of chloride ions. The pitting potential （Epit） decreases linearly with Iog[CI-]. Correspondingly, the point defect diffusion coefficient （Do） of the passive film increases linearly with increasing Iog[CI-]. The results also indicate that the pitting corrosion of 316L SS follows the adsorption mechanism in NaCI solution.
Guozhe MengYuan LiYawei ShaoTao ZhangYanqiu WangFuhui Wang
Nanocrystalline nickel coatings with grain size of 50 nm were annealed in vacuum at 200 ℃ and 400 ℃ for 10 min, Their microstructures were investigated by transmission electron microscopy （TEM）. And their corrosion behaviors were studied by means of polarization and electrochemical impedance spectroscopy （EIS）, The results showed that their grain size grew up to about 60 nm （200 ℃） and 500 nm （400 ℃）, respectively, The specimen annealed at 200 ℃ possessed higher density of twins in compared with the counterparts of as-deposited and annealed at 400 ℃, The normal grain size effect on the corrosion behavior was not observed, However, it was found that the corrosion resistance of the coating linearly changed with the density of twins.
Guozhe MengYang LiYawei ShaoTao ZhangYanqiu WangFuhui WangXuequn ChengChaofang DongXiaogang Li
