A Study on the Oxidation Behavior of Nickel Coatings with Different Grain Sizes and Preferred Orientations

Abstract

Ni coatings with different grain sizes and preferred orientations were produced by the control of current density during a direct current electrodepositing process. The effects of grain size reduction and preferred orientation on the oxidation behavior in air at 600°C and 960°C of Ni coatings were investigated respectively. An important and interesting result is that after oxidation at 600°C, the Ni coating obtained at lower current density has a better oxidation resistance, whereas after oxidation at 960°C, the Ni coating obtained at higher current density has a more compact scale and a better oxidation resistance. For the Ni coatings oxidation at 600°C, the oxidation behavior was mainly influenced by grain size, whereas in the case of the Ni coatings oxidation at 960°C, the oxidation behavior was only slightly influenced by grain size. The changes in oxidation behavior of Ni coatings at 960°C can be attributed to the different preferred orientation and the corresponding oxidation mechanism.