Effect of Cu3N layer thickness on Corrosion and Ni release properties of Cu3N/NiTiCu shape memory thin films

In the present study Cu3N/NiTiCu/Si thin films were successfully grown using magnetron sputtering technique. The thickness of nanocrystalline Cu3N was varied from 200 nm to 415 nm and effect of Cu3N layer thickness on structural, phase transformation, morphological, corrosion and Ni release properties of Cu3N/NiTiCu/Si was studied. The NiTiCu/Si thin films exhibit shape memory effect even after depositing Cu3N protective layer. Cu3N(200, 305 nm)/NiTiCu/Si thin films possess low corrosion current density with higher corrosion potential and therefore exhibit better corrosion resistance as compared Cu3N(415nm)/NiTiCu/Si film. The amount of Ni ions released in SBF solution was almost not detectable in case of 200, 305 nm thin Cu3N layer but increased significantly on increasing the thickness of Cu3N layer to 415 nm. Cu3N(415nm)/NiTiCu/Si exhibit much reduced corrosion resistance and Ni ion release impeding capability. This can be explained by decrease in adherence of Cu3N (similar to 415nm) layer on NiTiCu/Si thin film due to its increased thickness. This work is of immense technological importance due to its variety of its BioMEMS applications.