Electron microscopic investigations on the morphology and crystal growth characteristics of black nickel thin films

SummaryElectron microscopy studies were made on thin films of black nickel coatings during the initial stages of electrocrystallisation. Ni-Zn-S, Ni-Zn-Fe-S, Ni-Cd-Zn-Fe-S, and Ni-Mo-Fe-Mn were the four different types of black coatings examined. The coatings were electrocrystallised from sulphate baths with ammonium thiocyanate as the blackening agent in most experiments. Interesting morphological and crystal growth patterns were observed for the different types. Introduction of iron significantly alters the crystal growth characteristics. The mechanical and optical absorption properties of these films can be understood from the crystal growth behaviour.