Electrodeposition of palladium films on Ni-Co coatings

Co-Ni alloys have the properties of high hardness, good wear and corrosion resistance. A transition layer of Co-Ni coating will help enhance the hydrogen sensing stability of Pd films. In this work, Pd films were electrodeposited on Co-Ni coated copper substrate and silicon wafers. The influence of deposition parameters on the microstructure of Co-Ni coatings and Pd films were investigated. Experimental results indicated that scallop shell-like Co-Ni alloys could be fabricated on copper wafers. The tendency to form the shell-like deposits increased with increase of deposition time. While on silicon wafers, scallop shell-like Co-Ni alloys could not be fabricated. SEM and AFM analyses indicated that both composite films have a large surface area. Results showed that Pd films could be shaped by the prime films and thus maintain a large surface area.