Effects of the bias voltage on the microstructure, mechanical and tribological properties of ZrN/α-SiN_x nanoscaled multilayer films

The ZrN/α-SiN_x nanoscaled multilayer films were deposited under different substrate bias voltage by reactive magnetron sputtering. The microstructures of these films were analyzed using high resolution transmission electron microscope(HRTEM). The mechanical and tribological properties of these films were comparatively investigated by nanoindenter and ball-on-disc tribometer in vacuum condition, respectively. The results reveal that lower bias condition may result ZrN layers characterized with amorphous (or amorphous-like) microstructrue in multilayer films. And the higher bias voltage condition may result mixing of interfaces between ZrN layers and SiN_x layers in multilayer films. The transformation from crystal to amorphous microstructure of ZrN layers and interface mixing in multilayer films may both degrade the mechanical and tribological properties of the ZrN/α-SiN_x nanoscaled multilayer films. The appropriate bias voltage (-80 V) favors the formation of the sharp coherent interfaces between the crystalline ZrN layers and amorphous SiN_x layers. As a result, the ZrN/α-SiN_x nanoscaled multilayer film prepared under -80 V shows better mechanical and tribological properties.