Microstructure and corrosion characteristics of CrN/NiP sputtering thin films

The CrN top layer and NiP interlayer were sequentially deposited to form a CrN/NiP composite coating through sputtering technique. The CrN/NiP coating systems deposited at 350 °C, 450 °C, and 550 °C, showed amorphous/nanocrystalline, nanocrystallize with precipitations, and fully crystallized microstructure respectively for the NiP interlayers. With the introduction of NiP interlayer, the coating assemblies exhibited superior corrosion characteristics than single CrN coatings. The amorphous NiP interlayer deposited at 350 °C revealed a lower corrosion current as compared to those with crystallized NiP layers owing to their structural defects in the alloy layer. With the combination of CrN and NiP layers the corrosion attach was retarded and a better corrosion resistance was found for the CrN/NiP composite coating.